JP7178973B2 - protection control system - Google Patents

Description

This disclosure relates to protection control systems.

In recent years, as a form of a protection relay device, a protection control system compatible with a process bus as disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2012-65433) is becoming common. In this protection control system, the function of the conventional protection relay device is divided into two, each of which is composed of an individual unit.

Specifically, an electric quantity detection device called a Merging Unit (MU) and a protection control device called an IED (Intelligent Electronic Device) are provided. The MU takes in a detection signal of the electric quantity (that is, current, voltage, etc.) of the electric power system, and A/D (Analog to Digital) converts the taken signal. MU transmits the data obtained by A/D conversion to IED via a process bus. The IED performs relay calculations based on the received data from the MU.

When the protection control system disclosed in Patent Literature 1 is used to protect a power transmission line by a current-differential relay method, it is necessary to synchronize the sampling timings of the quantity of electricity at both ends of the power transmission line. Patent Document 1 discloses (i) a synchronization method using a GPS (Global Positioning System) signal. However, this synchronization method (i) can be problematic in terms of availability since GPS signals may not be received successfully. As another method, there is (ii) the conventionally used synchronization method disclosed in Patent Document 2. However, this method (ii) requires special hardware for sampling synchronization control.

Non-Patent Document 1 (Denki Kyodo Kenkyu, Vol. 71, No. 1, Section 6-2) discloses an IP (Internet Protocol)-PCM (Pulse Code Modulation) current differential relay to which a process bus is applied. Specifically, the PCM current differential relay IEDs facing each other across the transmission line are synchronized with each other, but the MU and the PCM current differential relay IEDs are asynchronous at the substation premises at each end of the transmission line. This is because, if the MU and the IED for the PCM current differential relay are synchronized, it will be necessary to synchronize other IEDs sharing the MU in each electric station premises.

In the configuration of Non-Patent Document 1, the current sampling timings at both ends of the transmission line are different, so it is necessary to calculate the current sampling data corresponding to the same time. For synchronous control of the IEDs for PCM current differential relays facing each other across the transmission line, for example, a time synchronization protocol (PTP: Precision Time Protocol) defined by IEC61588 or the like is used. However, PTP requires a special function in the switches that make up the network, resulting in an expensive system configuration.

Many conventional power transmission line protection devices to which a process bus is not applied realize sampling synchronization by the method disclosed in Japanese Patent Application Laid-Open No. 2002-200022. In this case, the analog input circuit, the transmission circuit, and the relay arithmetic circuit are mounted in the same unit, and it is an integrated unit configuration in which all components operate in synchronization with one sampling synchronization signal.

JP 2012-65433 A JP-A-62-262614

"Design rationalization of protection relay system by new communication technology", Denki Kyodo Kenkyu, Vol. 71, No. 1, Chapter 6, Section 6-2 "IP-PCM relay applying process bus", p. 196-197

In the protection relay system of Non-Patent Document 1, the IEDs for PCM current differential relays facing each other across the power transmission line need to perform synchronization control equivalent to the conventional one. This complicates the hardware configuration. Also, when executing synchronous control using a PTP master connected to an IP network, it is necessary to implement a communication protocol for sending and receiving data with the PTP master. The problem arises that it becomes impossible to

This disclosure takes the above problems into consideration, and aims to: (ii) to provide a protection control system that can be realized with a simple hardware configuration without requiring synchronous control between them;

An embodiment of a protection control system for protecting a protection section of a transmission line includes a first electricity detection device, a first protection control device, a second electricity detection device, a second protection control and a device. The first electric quantity detection device is provided at the first end of the protection section, and generates first current detection data by sampling the current of the transmission line at the first sampling period. The first protection control device is provided at the first end and outputs first transmission data based on first current detection data to the communication path at a first transmission cycle. The second electric quantity detection device is provided at the second end of the protection section, and generates second current detection data by sampling the current of the transmission line at the second sampling period. The second protection control device is provided at the second end, is connected to the first protection control device via a communication path, and transmits second transmission data based on the second current detection data at a second transmission cycle. Output to communication path. The first sampling period, the first transmission period, the second sampling period, and the second transmission period are asynchronous with each other. The first protection control device has a first time difference from when the first current detection data is received from the first electric quantity detection device to when the first transmission data is transmitted for each first transmission cycle. , and a second time difference from the transmission of the first transmission data to the reception of the second transmission data. The second protection control device sets a third time difference from receiving the second current detection data from the second electrical quantity detection device to transmitting the second current detection data for each second transmission cycle. and a fourth time difference from the transmission of the second transmission data to the reception of the first transmission data. At least one of the first protection control device and the second protection control device outputs current detection data on the self-end side based on the first time difference, the second time difference, the third time difference, and the fourth time difference. is interpolated, and it is determined whether or not a fault has occurred in the protection section based on comparison between the interpolated current detection data and the current detection data at the other end.

According to the protection control system of the above embodiment, by interpolating the current detection data using the measured values of the first to fourth time differences, between the protection control devices facing each other across the protection section of the transmission line It is possible to realize a current differential relay type transmission line protection control system with a simple hardware configuration without requiring synchronous control.

1 is a block diagram showing the configuration of a protection control system according to Embodiment 1; FIG. 2 is a block diagram showing an example of the hardware configuration of the electric quantity detection device and the protection control device of FIG. 1; FIG. FIG. 2 is a block diagram showing a functional configuration of a protection control device at end A in FIG. 1; 4 is a block diagram showing a specific configuration example of a transmission timing control unit in FIG. 3; FIG. FIG. 4 is a timing diagram showing a first example for explaining calculation of timing deviation; FIG. 5 is a timing diagram showing a second example for explaining calculation of timing deviation; FIG. 11 is a timing diagram showing a third example for explaining calculation of timing deviation; FIG. 11 is a timing diagram showing a fourth example for explaining calculation of timing deviation; FIG. 11 is a timing diagram showing a fifth example for explaining calculation of timing deviation; FIG. 4 is a diagram for explaining the timing of calculation and transmission of interpolated current values; FIG. 11 is a diagram for explaining timings of calculation and transmission of an interpolated current value Ia(db32) of FIG. 10; FIG. 4 is a flow chart showing the operation of the transmission timing control unit in FIG. 3; FIG. 4 is a flow chart showing the operation of the protection control system of Embodiment 1; 9 is a flow chart showing the operation of the protection control system of Embodiment 2; FIG. 10 is a diagram for explaining the operation of the protection control system when the protection section has three terminals;

Hereinafter, each embodiment will be described in detail with reference to the drawings. Although the case where the protection section of the transmission line has two terminals will be mainly described below, it goes without saying that the technique according to the present disclosure can also be applied to the case where the protection section has three or more terminals. In the following description, the same reference numerals are given to the same or corresponding parts, and the description thereof will not be repeated.

Embodiment 1.
[Configuration of protection control system]
FIG. 1 is a block diagram showing the configuration of a protection control system according to Embodiment 1. FIG. Protection and control system 200 of FIG. 1 protects a power system including transmission line 21 . The transmission line 21 is, for example, a three-phase transmission line, but FIG. 1 representatively shows only one of the three phases for the sake of simplicity.

The A end of the transmission line 21 is provided with an A end substation 100A, and the B end of the transmission line 21 is provided with a B end substation 100B. The protection control system 200 includes a voltage transformer 26A, a current transformer 27A, an electric quantity detection device 30A, protection control devices 60A and 80A, and a reference signal generation device 25A in the A-end substation 100A. The protection control system 200 includes a voltage transformer 26B, a current transformer 27B, an electric quantity detection device 30B, protection control devices 60B and 80B, and a reference signal generation device 25B in the B-end substation 100B. Hereinafter, when distinguishing between the same or corresponding configurations at the A end and the B end, A and B are added to the end of the reference numerals. For matters common to the A end and the B end, the reference numerals A and B at the end may be omitted.

As an example in the present disclosure, the electrical quantity detection device 30A may be referred to as a first electrical quantity detection device, and the protection control device 60A may be referred to as a first protection control device. Further, in the present disclosure, as an example, the electrical quantity detection device 30B may be referred to as a second electrical quantity detection device, and the protection control device 60B may be referred to as a second protection control device.

As shown in FIG. 1, the voltage transformer 26A detects the voltage value VaA at the A terminal of the transmission line 21. As shown in FIG. The current transformer 27A detects the current value IaA at the A terminal of the power transmission line 21 . Voltage transformer 26B detects voltage VaB at B end of transmission line 21 . A current transformer 27B detects the current IaB at the B end of the transmission line 21 . Although not shown in FIG. 1, the voltage transformers 26A and 26B and the current transformers 27A and 27B are provided for each phase of the three-phase transmission line.

The electric quantity detection device 30A samples the voltage value VaA and the current value IaA at the A terminal detected by the voltage transformer 26A at sampling intervals based on the timing signal from the clock circuit CLK1. The electric quantity detection device 30A A/D (Analog to Digital) converts the sampled voltage value VaA and current value IaA. The electric quantity detection device 30A detects at least one of a digital voltage value VdA (also referred to as voltage detection data) and a current value IdA (also referred to as current detection data) after A/D conversion provided at the A terminal substation 100A. Output to protection control devices 60A and 80A.

Similarly, the electric quantity detection device 30B samples the voltage value VaB and the current value IaB at the B terminal detected by the voltage transformer 26B at the sampling period based on the timing signal from the clock circuit CLK3. The electric quantity detection device 30B A/D converts the sampled voltage value VaB and current value IaB. The electric quantity detection device 30B detects at least one of a digital voltage value VdB (also referred to as voltage detection data) and a current value IdB (also referred to as current detection data) after A/D conversion provided at the B-end substation 100B. Output to the protection control devices 60B and 80B. The electrical quantity detection devices 30A and 30B are also called merging units (MU).

The electric quantity detection device 30A at the A end further takes in the detected values of a voltage transformer and a current transformer (not shown) provided at other locations in the A end substation 100A, and performs A/D conversion. may be configured to In this case, the electric quantity detection device 30A transmits the A/D-converted electric quantities of other locations to the protection control devices 60A and 80A provided at the A-end substation 100A. In addition, the electric quantity detection device 30A is configured to output the digital voltage value VdB and current value IdB after A/D conversion to another protection control device (not shown) provided in the A-end substation 100A. may have been The same applies to the electrical quantity detection device 30B at the B end.

The protection control devices 60A and 80A use at least one of the voltage detection data and the current detection data acquired from the electrical quantity detection device 30A at the A terminal to perform protection relay calculation. Similarly, the protection control devices 60B and 80B use at least one of the voltage detection data and the current detection data obtained from the electrical quantity detection device 30B at the B end to perform protection relay calculation.

Here, the protection control device 60A at the A end and the protection control device 60B at the B end are interconnected via a dedicated communication path 20. FIG. Each of the protection controllers 60A, 60B functions as a current differential protection relay element.

Specifically, time-series current detection data at the A terminal based on the detection value by the electric quantity detection device 30A is input to the protection control device 60A. The protection control device 60A transmits transmission data based on the received current detection data to the protection control device 60B at the B end via the communication path 20 at a transmission cycle based on the timing signal from the clock circuit CLK2.

Similarly, time-series current detection data at the B end based on the detection value by the electric quantity detection device 30B is input to the protection control device 60B. Protection control device 60B transmits transmission data based on the received current detection data to protection control device 60A at the A end via communication path 20 at a transmission cycle based on the timing signal from clock circuit CLK4.

Based on the current detection data at the A terminal and the transmission data received via the communication path 20 from the protection control device 60B, the protection control device 60A determines the current value at the A terminal that can be regarded as the same time within the allowable error range. and the current value at the B end. Then, the protection control device 60A determines whether or not there is a failure in the transmission line 21 between the A terminal and the B terminal (that is, within the protection section) based on the result of the difference calculation of the current values.

Similarly, the protection control device 60B, based on the current detection data at the B end and the transmission data received from the protection control device 60A via the communication path 20, determines that the A end can be regarded as the same time within the allowable error range. and the current value at the B end. Then, the protection control device 60B determines whether there is a failure in the transmission line 21 between the A terminal and the B terminal (that is, within the protection section) based on the result of the difference calculation of the current values.

On the other hand, the other protection control device 80A at the A end executes protection relay calculation based only on the detection data at the A end, that is, not based on the detection data at the B end. The other protection control device 80B at the B end performs protection relay calculations based only on the detection data at the B end, that is, not based on the detection data at the A end. For example, each of the protection control devices 80A, 80B operates as a distance relay element other than a current differential relay element, an overcurrent relay element, and the like.

In FIG. 1, the protection control devices 60A and 80A provided at the A-end substation 100A are configured as separate units, but they may be integrated. Similarly, the protection control devices 60B and 80B provided at the B-end substation 100B may be integrated.

At the A terminal, the reference signal generation device 25A generates a reference signal Ref1 that serves as a reference for sampling timing in the electrical quantity detection device 30A and supplies it to the electrical quantity detection device 30A. Therefore, the clock circuit CLK1 provided in the electric quantity detection device 30 generates a timing signal in which the reference signal is synchronized with Ref1.

The reference signal generator 25A also supplies a common reference signal Ref1 to other electrical quantity detectors (not shown) provided at the A-end substation 100A. Therefore, sampling synchronization is possible in the plurality of electric quantity detection devices provided at the A-end substation 100A.

Similarly, at the B end, the reference signal generation device 25B generates a reference signal Ref1 that serves as a reference for sampling timing in the electrical quantity detection device 30B, and supplies it to the electrical quantity detection device 30B. Therefore, the clock circuit CLK1 provided in the electric quantity detection device 30 generates a timing signal in which the reference signal is synchronized with Ref1.

The reference signal generator 25B also supplies a common reference signal Ref1 to other electric quantity detectors (not shown) provided at the B-end substation 100B. Therefore, sampling synchronization is possible in the plurality of electric quantity detection devices provided at the B-end substation 100B.

Here, the protection control system 200 of this embodiment is characterized in that it is not necessary to synchronize the sampling timing at the A terminal and the sampling timing at the B terminal. That is, the reference signal generated by the reference signal generation device 25A at the A end may not be synchronized with Ref1, and the reference signal generated by the reference signal generation device 25B at the B end may not be synchronized with Ref2. Similarly, the clock circuit CLK1 provided in the electrical quantity detection device 30A at the A end and the clock circuit CLK3 provided in the electrical quantity detection device 30B at the B end need not operate synchronously.

Furthermore, at the A terminal, the clock circuits CLK2 and CLK5 provided in the protection control devices 60A and 80A do not need to operate in synchronization with the clock circuit CLK1 provided in the electric quantity detection device 30A. At the B end, the clock circuits CLK4 and CLK6 provided in the protection control devices 60B and 80B, respectively, need not operate in synchronization with the clock circuit CLK2 provided in the electric quantity detection device 30B. That is, in FIG. 1, the clock circuits CLK1-CLK6 need not be synchronized with each other.

Protection control devices 60A and 60B in protection control system 200 are configured to be able to perform current differential relay calculation even if clock circuits CLK1 to CLK4 are asynchronous as described above. A specific method will be described later with reference to FIGS.

[Hardware configuration example of electric quantity detection device and protection control device]
An example in which the electric quantity detection device 30 and the protection control device 60 in FIG. 1 are configured based on a microcomputer will be described below. The protection control device 80 in FIG. 1 has the same configuration as the protection control device 60 .

Note that unlike the following examples, the electric quantity detection device 30 and the protection control devices 60 and 80 may be configured based on an electronic circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). . Alternatively, the electric quantity detection device 30 and the protection control devices 60 and 80 may be configured by combining an electronic circuit such as FPGA or ASIC with a microcomputer.

FIG. 2 is a block diagram showing an example of the hardware configuration of the electric quantity detection device and the protection control device of FIG. The configuration of the electrical quantity detection device 30 in FIG. 2 is common to the electrical quantity detection devices 30A and 30B in FIG. Similarly, the configuration of protection control device 60 in FIG. 2 is common to protection control devices 60A and 60B in FIG.

Referring to FIG. 2, electric quantity detection device 30 includes input conversion section 31, A/D conversion section 35, arithmetic processing section 40, interface section 50, and clock circuit CLK1 (or CLK3). .

The input conversion unit 31 is an input unit to which the current signal of each phase output from the current transformer 27 of FIG. 1 and the voltage signal of each phase output from the voltage transformer 26 of FIG. 1 are input. The input converter 31 is provided with a transformer as an input converter 32 (32_1, 32_2, . . . ) (INCONV) for each channel. A current signal of each phase and a current signal of each phase are input to each channel (only two channels are representatively shown in FIG. 2). Each input converter 32 converts the current signal and voltage signal from the current transformer 27 and the voltage transformer 26 into signals of voltage levels suitable for signal processing in the A/D converter 35 and the arithmetic processor 40 .

The A/D converter 35 includes an analog filter 36 (AF: Analog Filter), a sample and hold circuit 37 (S/H: Sample and Hold Circuit), a multiplexer 38 (MPX: Multiplexer), and an analog digital (A/D ) converter 39 . Analog filters 36 (36_1, 36_2, . . . ) and sample-and-hold circuits 37 (37_1, 37_2, .

Each analog filter 36 is a filter provided to remove aliasing errors during A/D conversion. Each sample hold circuit 37 samples and holds the signal that has passed through the corresponding analog filter 36 at a predetermined sample rate (also called sampling frequency) (for example, 4800 Hz). A multiplexer 38 sequentially selects the voltage signals held in each sample hold circuit 37 . A/D converter 39 converts the signal selected by the multiplexer into a digital value.

The arithmetic processing unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), and a ROM 43 (Read Only Memory). Each of these elements are interconnected via a bus 44 . The arithmetic processing unit 40 may include an electrically rewritable nonvolatile memory (not shown) such as a flash memory. RAM42 and ROM43 are used as main memory of CPU41. The CPU 41 controls the operation of the electrical quantity detection device 30 as a whole according to programs stored in the ROM 43 and nonvolatile memory.

The interface unit 50 includes a communication circuit 51 (TX/RX) for transmitting data to the protection control device 60 via a communication line 52 (also called process bus).

The clock circuit CLK1 (or CLK3) operates in synchronization with the reference signal Ref1 (or Ref2). Each component of the electric quantity detection device 30 operates based on the timing signals (TMS1 and TMS2 in FIG. 3) output from the clock circuit CLK1 (or CLK3).

The protection control device 60 includes an interface section 61 and an arithmetic processing section 70 . The interface unit 61 includes a communication circuit 62 (TX/RX1), a transmission/reception circuit 63 (TX/RX2), a digital output circuit 64 (D/O: Digital Output), and a clock circuit CLK2 (or CLK4).

The communication circuit 62 (TX/RX1) receives data output from the communication circuit 51 (TX/RX) of the electric quantity detection device 30 and transmitted via the communication line 52 (process bus). The transmission/reception circuit 63 (TX/RX2) communicates with a host computer (not shown) according to a predetermined protocol, for example, via a communication line (not shown) called a station bus. A digital output circuit 64 (D/O) is an interface circuit for outputting a signal to an external device. For example, the digital output circuit 64 outputs a trip signal TS to a circuit breaker (not shown) provided in the transmission line 21 of FIG. In some cases, the trip signal TS is output from the communication circuit 62 to the communication line 52 , received by the communication circuit 51 , and output to the circuit breaker via the electric quantity detection device 30 .

The arithmetic processing unit 70 includes a CPU 71 , a RAM 72 and a ROM 73 . Each of these elements are interconnected via a bus 74 . The arithmetic processing unit 70 may include an electrically rewritable nonvolatile memory (not shown) such as a flash memory. A RAM 72 and a ROM 73 are used as main memory of the CPU 71 . The CPU 71 operates according to programs stored in the ROM 73 and nonvolatile memory.

The clock circuit CLK2 (or CLK4) operates in synchronization with the reference signal Ref3 (or Ref4). Each component of the protection control device 60 operates based on the timing signal (TMS2 in FIG. 3) output from the clock circuit CLK2 (or CLK4).

[Functional configuration of protection control device]
Next, in the protection control system 200 of FIG. 1, functional configurations of the protection control devices 60A and 60B that constitute the current differential relay elements will be described. In the following description, the components of the protection control device 60A and the electrical quantity detection device 30A at the A end may be referred to as "A end side" components. Similarly, the components of the protection control device 60B and the electrical quantity detection device 30B at the B end may be referred to as "B end side" components. Also, the amount of electricity in the transmission line at the A end may be described as the "A end side" electricity amount, and the electricity amount in the transmission line at the B end may be described as the "B end side" electricity amount.

FIG. 3 is a block diagram showing the functional configuration of the protection control device at end A in FIG. FIG. 3 also shows main components of the electrical quantity detection device 30A at the A end, main components of the electrical quantity detection device 30B at the B end, and a protection control device 60B at the B end. Also, although FIG. 3 shows only the functional configuration of the protection control device 60A at the A end, the functional configuration of the protection control device 60B at the B end is substantially the same.

Referring to FIG. 3 , A-end side protection control device 60A includes a data receiver 110 , a data storage 111 , a data transmitter 113 , a data receiver 112 and a timing deviation calculator 114 . A-end side protection control device 60A further includes transmission timing control section 115 , interpolation calculation section 116 , and relay calculation section 117 . The protection control device 60B on the B end side also has a similar configuration.

In FIG. 3, data receiver 110 corresponds to communication circuit 62 in FIG. The data storage unit 111 corresponds to the RAM 72 in FIG. 2 and a non-volatile memory (not shown) such as a flash memory. The data transmission section 113 and the data reception section 112 correspond to the transmission/reception circuit 63 in FIG. The functions of the timing deviation calculator 114, the interpolation calculator 116, and the relay calculator 117 are realized by the CPU 71 in FIG. 2 operating according to a program. A configuration example of the transmission timing control section 115 will be described later with reference to FIG.

The data receiving unit 110 on the A-end side receives time-series current detection data from the electric quantity detection device 30A on the A-end side. The data receiving section 110 on the A terminal side records the reception time of the current detection data based on the timing signal TMS2 from the clock circuit CLK2. Similarly, the data receiving unit 110 on the B-end side receives time-series current detection data from the electric quantity detection device 30B on the B-end side. The data receiving section 110 on the B end side records the reception time of the current detection data based on the timing signal from the clock circuit CLK4.

Here, the sample-and-hold circuit 37A on the A-end side and the sample-and-hold circuit 37B on the B-end side sample the electric quantity at a constant cycle. However, in the case of this embodiment, the clock circuit CLK1 in the electrical quantity detection device 30A and the clock circuit CLK3 in the electrical quantity detection device 30B are not synchronized. Therefore, the sampling timing of the electrical quantity at the A terminal and the sampling timing of the electrical quantity at the B terminal are usually different. As a result, the reception times of the current detection data in the data reception units 110 of the electric quantity detection devices 30A and 30B are also usually different.

The data transmission unit 113 and the data reception unit 112 on the A end side transmit and receive data to and from the data transmission unit 113 and the data reception unit 112 on the B end side via the communication path 20 . Specifically, the data transmission unit 113 on the A-end side transmits the time-series current detection data or the interpolated value of the current detection data (collectively referred to as transmission data) at the A-end based on the detection value by the electric quantity detection device 30A to B It is transmitted to the data receiving unit 112 on the end side. The data transmission unit 113 on the A terminal side records the transmission time of the transmission data. In addition, the data receiving unit 112 on the A-end side receives the time-series current detection data at the B-end based on the detection value by the electric quantity detection device 30B or the interpolated value of the current detection data from the B-end-side data transmission unit 113. do. The data receiving unit 112 on the A terminal side records the reception time of the data.

Similarly, the data transmission unit 113 on the B end side transmits the time-series current detection data or the interpolated value of the current detection data (collectively referred to as transmission data) at the B end based on the detection value by the electric quantity detection device 30B to the A end. data receiving unit 112 on the side. The data transmission unit 113 on the B end side records the transmission time of the transmission data. In addition, the data receiving unit 112 on the B end side receives time-series current detection data or an interpolated value of the current detection data at the A end based on the detection value by the electric quantity detection device 30A from the data transmission unit 113 on the A end side. do. The data reception unit 112 on the B end side records the reception time of the data.

Here, the transmission timing of transmission data from the A terminal to the B terminal is determined based on the timing signal TMS2 from the clock circuit CLK2 on the A terminal side. The transmission timing of transmission data from the B terminal to the A terminal is determined based on the timing signal from the clock circuit CLK4. If the clock circuits CLK2 and CLK4 operate synchronously with each other, the transmission timing of the transmission data from the A terminal to the B terminal and the transmission timing of the transmission data from the B terminal to the A terminal are the same. be. However, in the protection control system 200 of the present embodiment, since the clock circuits CLK2 and CLK4 are not synchronized with each other, the transmission times of the transmission data on the A terminal side and the B terminal side are different.

The timing deviation calculation unit 114 on the A-end side calculates the time difference between the time when the current detection data is received from the electric quantity detection device 30A and the time when the data transmission unit 113 on the A-end side transmits the transmission data to the B-end side. Calculate MSd. Furthermore, in data transmission section 113 and data reception section 112, timing deviation calculation section 114 calculates the difference between the transmission time of transmission data on the A terminal side to B terminal side and the reception time of transmission data from B terminal side. Compute the time difference TM. These time differences MSd and TM are calculated with reference to timing signal TMS2 from clock circuit CLK2. When interpolation calculation of current detection data is performed in the protection control device 60B on the B-end side, the data transmission section 113 on the A-end side transmits the calculated time differences MSd and TM to the data reception section 112 on the B-end side. .

Similarly, the timing deviation calculation unit 114 on the B end side calculates the difference between the reception time of the current detection data from the electric quantity detection device 30B and the transmission time of the transmission data to the A end side by the data transmission unit 113 on the B end side. Calculate the time difference SSd between Furthermore, in data transmission section 113 and data reception section 112, timing deviation calculation section 114 calculates the difference between the transmission time of transmission data on the B terminal side to the A terminal side and the reception time of transmission data from the A terminal side. Compute the time difference TS. These time differences SSd and TS are measured with reference to the timing signal from clock circuit CLK4. When interpolation calculation of current detection data is performed in the protection control device 60A on the A-end side, the data transmission section 113 on the B-end side transmits the calculated time differences SSd and TS to the data reception section 112 on the A-end side. .

In the present disclosure, as an example, the time difference MSd may be referred to as the first time difference, the time difference TM may be referred to as the second time difference, the time difference SSd may be referred to as the third time difference, and the time difference TS may be referred to as the fourth time difference. .

The timing deviation calculator 114 on the A-end side further calculates a timing deviation Δt between the timing signal TMS2 generated by the clock circuit CLK2 on the A-end side and the timing signal generated by the clock circuit CLK4 on the B-end side. The timing deviation Δt is equal to the time difference between the transmission time of the transmission data on the A terminal side and the transmission time of the transmission data on the B terminal side. The above time differences TM and TS are used in the calculation of the timing deviation Δt. Furthermore, in this calculation, it is assumed that the transmission delay time through the communication channel 20 from the A end to the B end and the transmission delay time through the communication channel 20 from the B end to the A end are approximately equal. This transmission delay time is hereinafter referred to as Td. A specific method of calculating the timing deviation Δt will be described later with reference to FIGS. 5 to 9. FIG.

The timing deviation calculator 114 on the B end side similarly calculates the timing deviation Δt. Here, when the timing signal TMS2 generated by the clock circuit CLK2 on the A terminal side lags behind the timing signal generated by the clock circuit CLK4 on the B terminal side, the timing deviation Δt is assumed to be positive. That is, when the transmission time of the transmission data on the A terminal side is later than the transmission time of the corresponding transmission data on the B terminal side, the timing deviation Δt is positive. Conversely, when the timing signal TMS2 generated by the clock circuit CLK2 on the A terminal side leads the timing signal generated by the clock circuit CLK4 on the B terminal side, the timing deviation Δt is negative. That is, when the transmission time of the transmission data on the A terminal side is earlier than the transmission time of the corresponding transmission data on the B terminal side, the timing deviation Δt becomes negative.

The timing deviation calculator 114 on the A-end side further calculates a timing deviation ΔSd between the sample timing of the electrical quantity by the electrical quantity detection device 30A on the A-end side and the sampling timing of the electrical quantity by the B-end side 30B. Here, the time at which the protection control device 60A receives the detected value of the quantity of electricity from the quantity of electricity detection device 30A at the A terminal is da. Let db be the time at which the protection control device 60B receives the detected value of the corresponding electrical quantity from the electrical quantity detection device 30B at the B end. In this case, the timing deviation ΔSd is substantially equal to the time difference between the reception time da on the A-end side and the reception time db on the B-end side. In calculating the timing deviation ΔSd, the time differences MSd and SSd and the timing deviation Δt are used. Furthermore, in this calculation, the time from when the electrical quantity detection device 30 samples the electrical quantity to when the protection control device 60 receives the A/D-converted current detection data is assumed to be approximately equal. A specific method of calculating the timing deviation ΔSd will be described later with reference to FIGS. 5 to 9. FIG.

The timing deviation calculator 114 on the B end side similarly calculates the timing deviation ΔSd. Here, when the sample timing of the electrical quantity by the electrical quantity detection device 30A on the A end side lags behind the sample timing of the electrical quantity by the electrical quantity detection device 30B on the B end side, the timing deviation ΔSd is assumed to be positive. . Therefore, when the reception time da on the A-end side is later than the corresponding reception time db on the B-end side, the timing deviation ΔSd is normally positive. Conversely, when the timing for sampling the electrical quantity by the electrical quantity detection device 30A on the A end side is ahead of the sampling timing for the electrical quantity by the electrical quantity detection device 30B on the B end side, the timing deviation ΔSd is made negative. . Therefore, when the reception time da on the A-end side is earlier than the corresponding reception time db on the B-end side, the timing deviation ΔSd is normally negative.

In the present disclosure, as an example, the timing deviation Δt may be referred to as a first timing deviation, and the timing deviation ΔSd may be referred to as a second timing deviation.

The transmission timing control section 115 on the A terminal side calculates the transmission timing of the transmission data by the data reception section 112 based on the time difference TM. Transmission timing control section 115 controls the transmission timing so that time difference TM is equal to or greater than the lower limit value greater than 0 and equal to or less than the upper limit value smaller than the transmission cycle of the transmission data. This makes it possible to reliably detect the time difference TM and the time difference TS for each transmission period. If the transmission time of the transmission data on the A-end side and the reception time of the transmission data from the B-end side are almost the same, it is possible that the transmission data from the B-end cannot be received in a certain transmission period. It is from. A specific configuration example of the transmission timing control section 115 will be described later with reference to FIG. It is sufficient that the transmission timing control section 115 is provided in either one of the protection control device 60A on the A-end side and the protection control device 60B on the B-end side.

The data storage unit 111 stores the current detection data received from the electrical quantity detection device 30 on the self end side and the current detection data or interpolated current data on the other end side received via the data reception unit 112 .

Interpolation calculation section 116 interpolates the current detection data based on the calculated timing deviation ΔSd to determine the current detection data on the A end side and the B end side at the same time. In this case, the detection data on the B-end side may be interpolated in accordance with the sample timing on the A-end side, or the detection data on the A-end side may be interpolated in accordance with the sample timing on the B-end side.

In Embodiment 1, the A-end side interpolating section 116 interpolates the current detection data received from the A-end side electric quantity detection device 30A in accordance with the sampling timing of the electric quantity at the B end side. Current detection data after interpolation (referred to as “interpolated current data 118 ” in the present disclosure) is stored in the data storage unit 111 . A specific interpolation calculation method will be described later with reference to FIGS.

The relay calculation unit 117 executes protection relay calculation based on current detection data and interpolation current data on the self-end side and the other-end side stored in the data storage unit 111 . Specifically, in the case of the first embodiment, each of the relay calculation units 117 on the A-end side and the B-end side calculates the current based on the interpolated current data on the A-end side and the current detection data on the B-end side. Executes calculations based on the differential relay method.

[Specific Configuration Example of Transmission Timing Control Unit]
FIG. 4 is a block diagram showing a specific configuration example of the transmission timing control section in FIG.

Referring to FIG. 4A, transmission timing control section 115 includes, as an example, frequency dividing circuit 120 and frequency dividing ratio control section 121 .

The frequency dividing circuit 120 outputs a trigger signal 119 that serves as a reference for the data transmission section 113 to transmit transmission data based on the timing signal TMS2 from the clock circuit CLK2. The frequency of the trigger signal 119 is, for example, 12 times the rated frequency of the power system (that is, corresponding to a 30° electrical angle cycle).

The frequency division ratio control section 121 controls the frequency division ratio of the frequency division circuit 120 based on the calculation result of the time difference TM by the timing deviation calculation section 114 . For example, frequency division ratio control section 121 increases the frequency of trigger signal 119 when time difference TM is less than the lower limit, and decreases the frequency of trigger signal 119 when time difference TM exceeds the upper limit. Thereby, the transmission timing control section 115 can control the transmission timing by the data transmission section 113 so that the time difference TM falls within the range of the lower limit value or more and the upper limit value or less.

Referring to FIG. 4B, transmission timing control section 115 includes frequency dividing circuit 120 and phase selecting circuit 122 as another example.

Frequency dividing circuit 120 outputs a large number of signals having different phases based on timing signal TMS2 from clock circuit CLK2. The frequency of each signal is, for example, 12 times the rated frequency of the power system (that is, corresponds to a 30° electrical angle cycle).

A phase selection circuit 122 selects a signal to be used as the trigger signal 119 from among many signals output from the frequency divider circuit 120 . Here, the phase selection circuit 122 changes the signal to be selected based on the calculation result of the time difference TM by the timing deviation calculator 114 . For example, the signal with the earlier phase is selected when the time difference TM is less than the lower limit, and the signal with the later phase is selected when the time difference TM exceeds the upper limit. Thereby, the transmission timing control section 115 can control the transmission timing by the data transmission section 113 so that the time difference TM falls within the range of the lower limit value or more and the upper limit value or less.

[Specific timing deviation and interpolation calculation method]
A method of calculating the time differences TM, TS, MSd, SSd and the timing deviations Δt, ΔSd will be described below with reference to FIGS. 5 to 9. FIG. In the following, the case where the timing deviation Δt is positive and negative and the case where the timing deviation ΔSd is positive and negative will be separately described.

Since the time differences TM, TS, MSd, SSd and the timing deviations Δt, ΔSd are calculated for each transmission cycle, they are numbered according to the transmission cycle. For example, the time difference TM is expressed as TM1, TM2, . The same is true for other time differences and timing deviations.

Also, in the following description, the transmission times of transmission data from the A terminal side are expressed as ta1, ta2, ta3, . . . The reception times of the current detection data received by the protection control device 60A from the electric quantity detection device 30A on the A-end side between time ta1 and time ta2 are expressed as da21, da22, da23, . More generally, the reception times of the current detection data at the A terminal between time ta_i−1 and time ta_i are represented by da_i_1, da_i_2, . . . (generically referred to as da_i_p).

Similarly, the transmission times of transmission data from the B end are expressed as tb1, tb2, tb3, . . . The reception times of the current detection data received by the protection control device 60B from the electric quantity detection device 30B on the B end side between time tb1 and time tb2 are expressed as db21, db22, db23, . More generally, the reception times of the current detection data at the B end between time tb_i−1 and time tb_i are represented by db_i_1, db_i_2, . . . (generically referred to as db_i_q).

(Example 1: When Δt>0, ΔSd>0)
FIG. 5 is a timing diagram showing a first example for explaining calculation of the timing deviation. FIG. 5 shows the case where the timing deviation Δt is positive and the timing deviation ΔSd is positive.

Common to FIGS. 5 to 9, the top row shows the timing at which the protection control device 60A receives the current detection data sampled by the electrical quantity detection device 30A at the A terminal. 5 to 8, the protection control device 60A receives current detection data from the electric quantity detection device 30A at times da12, da21, da22, da31, . . . (collectively referred to as da_i_p). The cycle in which the protection control device 60A receives current detection data from the electrical quantity detection device 30A is substantially equal to the cycle in which the electrical quantity detection device 30A samples the current of the electric power system.

Common to FIGS. 5 to 9, the second row from the top shows the timing at which the interpolated current data on the A-end side is transmitted to the B-end side. At each of times ta1, ta2, ta3, . Send. In the case of FIGS. 5 to 8, the data transmission period Ta is twice the sampling period in the electrical quantity detection device 30A.

Common to FIGS. 5 to 9, the third row from the top shows the timing at which current detection data on the B terminal side is transmitted to the A terminal side. Protection control device 60B transmits current detection data on the B end side to protection control device 60A on the A end via communication path 20 at each of times tb1, tb2, tb3, . . . (generically referred to as tb_i). The data transmission cycle Tb of the protection control device 60B is substantially equal to the data transmission cycle Ta of the protection control device 60A.

Common to FIGS. 5 to 9, the bottom row shows the timing at which the protection control device 60B receives the current detection data sampled by the electrical quantity detection device 30B at the B end. 5 to 8, protection control device 60B receives current detection data from electrical quantity detection device 30B at each of times db21, db22, db31, db32, . . . (generically referred to as db_i_q). The cycle in which the protection control device 60B receives current detection data from the electrical quantity detection device 30B is substantially equal to the cycle in which the electrical quantity detection device 30B samples the current of the power system. 5 to 8, the sampling cycle of the electric quantity detection device 30B is half the data transmission cycle Tb of the protection control device 60B.

Referring to FIG. 5, the interpolated current data transmitted from A-end protection control device 60A at time ta1 is received by B-end protection control device 60B at time rb1. The interpolated current data transmitted from the protection control device 60A at the A end at time ta3 is received by the protection control device 60B at the B end at time rb3. Let Td be the transmission delay time of the interpolated current data.

Similarly, the current detection data transmitted from the protection control device 60B at the B end at time tb2 is received by the protection control device 60A at the A end at time ra2. The current detection data transmitted from the protection control device 60B at the B end at time tb4 is received by the protection control device 60A at the A end at time ra4. The transmission delay time of the current detection data is equal to the reverse transmission delay time Td.

In the example of FIG. 5, the timing deviation Δt_i between the data transmission timing from the A-end protection control device 60A and the data transmission timing from the B-end protection control device 60B is
Δt_i=ta_i−tb_i (1)
is represented by As shown in the above formula (1), the timing deviation Δt_i is defined to be positive when the A-end is behind the B-end.

The protection control device 60A on the A-end side measures the time difference TM_i from the transmission of the interpolated current data on the A-end side to the reception of the current detection data on the B-end side. For example, the time difference between the transmission time ta2 and the reception time ra2 is TM2. The time difference TM_i is
TM_i=Td-Δt_i (2)
is represented by

The protection control device 60B on the B-end side measures the time difference TS_i from when the current detection data on the B-end side is transmitted to when the interpolated current data on the A-end side is received. For example, the time difference between transmission time tb3 and reception time rb3 is TS3. In the example of FIG. 5, the time difference TS_i is
TS_i=Td+Δt_i (3)
is represented by

From the above equations (2) and (3), the timing deviation Δt is
Δt_i=(TS_i−TM_i)/2 (4)
can be calculated by That is, the timing deviation Δt_i is 1/2 of the difference obtained by subtracting the time difference TM_i on the A-end side from the time difference TS_i on the B-end side.

The protection control device 60A on the A end side also measures the time difference MSd_i from when the current detection data is received from the electric quantity detection device 30A to when the interpolated current data is transmitted to the protection control device 60B on the B end side. For example, the time difference between the reception time da2 and the transmission time ta2 is MSd2. Similarly, the protection control device 60B on the B end side further measures the time difference SSd_i from when the current detection data is received from the electric quantity detection device 30B to when the current detection data is transmitted to the protection control device 60A on the A end side. do. For example, the time difference between the reception time db2 and the transmission time tb2 is SSd2.

Next, a method of calculating the timing deviation ΔSd_i of sample timing will be described. In the example of FIG. 5, the timing deviation ΔSd_i of sample timing between the A end side and the B end side is
ΔSd_i=da_i_p-db_i_q (5)
is represented. In the case of FIG. 5, p=q=2. As shown in the above equation (5), the timing deviation ΔSd_i is defined to be positive when the A-end lags behind the B-end.

Furthermore, in FIG. 5, the time interval from time db_i_q to time ta_i is
ta_i−db_i_q=ΔSd_i+MSd_i=SSd_i+Δt_i (6)
is represented. Rewriting the above equation (6), we get
ΔSd_i=Δt_i+SSd_i−MSd_i (7)
is obtained. That is, the timing deviation ΔSd_i of the sample timing can be obtained by adding the time difference SSd_i to the timing deviation Δt_i and subtracting the time difference MSd_i.

Based on the timing deviation ΔSd_i, the current detection data on the A-end side can be interpolated so as to synchronize with the sample timing on the B-end side. Specifically, the current value at the A terminal of the transmission line at the sample timing of the B terminal can be obtained by interpolation of the current detection data detected at the A terminal.

For example, in the case of FIG. 5, the current detection data on the A terminal side at time db22 can be obtained by linear approximation using the current detection value at time da21 and the current detection value at time da22. Specifically, the detected current value at the A terminal at time da21 is Ia(da21), and the detected current value at the A terminal at time da22 is Ia(da22). Let Ts be the sampling period of the current detection data at the A terminal. In this case, the current value Ia (db22) at the A terminal at time db22 is
Ia (db22)
= [ΔSd2・Ia(da21)+(Ts−ΔSd2)・Ia(da22)]/Ts
…(8)
is given by

(Example 2: When Δt>0, ΔSd<0)
FIG. 6 is a timing diagram showing a second example for explaining the calculation of the timing deviation. FIG. 6 shows the case where the timing deviation Δt_i is positive and the timing deviation ΔSd_i is negative.

Also in the example shown in FIG. 6, the above expressions (1) to (4) hold as they are. If the expression (5) in the case of Example 1 is used as the expression for the timing deviation ΔSd_i, the timing deviation ΔSd_i is negative in the case of FIG. That is, by modifying the above equation (5),
-ΔSd_i=db_i_q-da_i_p (5A)
, the absolute value of the timing deviation (-ΔSd_i) can be calculated. In the case of FIG. 6, p=q=2.

Also, in FIG. 6, the time interval from time db_i_q to time ta_i is
ta_i-db_i_q=MSd_i-(-ΔSd_i)=SSd_i+Δt_i
…(9)
is represented. By arranging the above equation (9), the same equation as the equation (7) in the case of Example 1 is obtained. However, in the case of this example, ΔSd_i<0.

Based on the timing deviation (-ΔSd_i), the current detection data on the A-end side can be interpolated so as to synchronize with the sample timing on the B-end side. For example, the current detection data on the A terminal side at time db22 can be obtained by linear approximation using the current detection value at time da22 and the current detection value at time da31. Specifically, let Ia(da22) be the detected current value at the A terminal at time da22, and Ia(da31) be the detected current value at the A terminal at time da31. Let Ts be the sampling period of the current detection data at the A terminal. In this case, the current value Ia (db22) at the A terminal at time db22 is
Ia (db22)
= [(Ts+ΔSd2)·Ia(da22)−ΔSd2·Ia(da31)]/Ts
…(Ten)
is given by

(Example 3: When Δt<0, ΔSd<0)
FIG. 7 is a timing diagram showing a third example for explaining the timing deviation calculation. FIG. 7 shows the case where the timing deviation Δt_i is negative and the timing deviation ΔSd_i is negative.

In the example shown in FIG. 7, the timing deviation Δt_i is negative if the equation (1) in the example is used as the equation for expressing the timing deviation Δt_i. That is, obtained by modifying the formula (1),
-Δt_i=tb_i_q-ta_i (1A)
, the absolute value of the timing deviation (-Δt_i) can be calculated. In the case of FIG. 7, q=2.

The protection control device 60A on the A-end side measures the time difference TM_i from the transmission of the interpolated current data on the A-end side to the reception of the current detection data on the B-end side. For example, the time difference between transmission time ta_i and reception time ra_i is TM_i. As shown in FIG. 7, the time difference TM_i is
TM_i=Td+(-Δt_i)=Td-Δt_i (11)
is represented by This formula (11) is the same as formula (2) in example 1.

The protection control device 60B on the B-end side measures the time difference TS from the transmission of the current detection data on the B-end side to the reception of the interpolated current data on the A-end side. For example, the time difference between transmission time tb3 and reception time rb3 is TS. As shown in FIG. 7, the time difference TS is
TS_i=Td-(-Δt_i)=Td+Δt_i (12)
is represented by This equation (12) is the same as equation (3) in example 1.

From the above equations (11) and (12), the timing deviation (-Δt_i) is
-Δt_i=(TM_i-TS_i)/2 (13A)
can be calculated. Rewriting the above equation (13A),
Δt_i=(TS_i-TM_i)/2 (13B)
is obtained. This formula (13B) is the same as the formula (4) in Example 1.

On the other hand, if the expression (5) in Example 1 is used as it is as an expression representing the timing deviation ΔSd_i, the timing deviation ΔSd_i becomes negative. In this case, equation (5A) in example 2 can be used to calculate the absolute value of the timing deviation (-ΔSd_i).

Furthermore, in FIG. 7, the time interval from time db_i_q to time ta_i is
ta_i-db_i_q=MSd_i-(-ΔSd_i)
=SSd_i-(-Δt_i) (14)
is represented. By arranging the above equation (14), the same equation as the equation (7) in the case of Example 1 is obtained. However, in the case of this example, ΔSd_i<0.

Based on the timing deviation (-ΔSd_i), the current detection data on the A-end side can be interpolated so as to synchronize with the sample timing on the B-end side. For example, the current detection data on the A terminal side at time db22 can be obtained by linear approximation using the current detection value at time da22 and the current detection value at time da31. Specifically, it is the same as the expression (10) in Example 2, so the description will not be repeated.

(Example 4: When Δt<0, ΔSd>0)
FIG. 8 is a timing diagram showing a fourth example for explaining calculation of the timing deviation. FIG. 8 shows the case where the timing deviation Δt_i is negative and the timing deviation ΔSd_i is positive.

Also in the example shown in FIG. 8, the above expressions (1A), (11), (12), (13A), and (13B) in the case of Example 3 hold as they are. Also, as the expression for the timing deviation ΔSd_i, the expression (5) in the case of Example 1 can be used as it is.

Also, in FIG. 8, the time interval from time db_i_q to time ta_i is
ta_i−db_i_q=MSd_i+ΔSd_i
=SSd_i-(-Δt_i) (15)
is represented. By arranging the above equation (15), the same equation as the equation (7) in the case of Example 1 is obtained.

Based on the timing deviation ΔSd, it is possible to interpolate the current detection data on the A-end side so as to synchronize with the sample timing on the B-end side. For example, the current detection data on the A terminal side at time db22 can be obtained by linear approximation using the current detection value at time da21 and the current detection value at time da22. Specifically, it is the same as the expression (8) in Example 1, so the description will not be repeated.

(Example 5: Modified example of the first example)
FIG. 9 is a timing diagram showing a fifth example for explaining calculation of the timing deviation. A fifth example is a modification of the first example shown in FIG.

As shown in FIG. 9, in the case of this example, the data transmission period Ta on the A terminal side is four times the sampling period in the electric quantity detection device 30A. Therefore, at four reception times da_i_1, da_i_2, da_i_3, and da_i_4 between transmission time ta_i−1 and transmission time ta_i, protection control device 60A receives current detection data from electric quantity detection device 30A. Also, the time difference MSd_i is defined as the time difference between the reception time da_i_3 and the transmission time ta_i. In this case, the timing deviation ΔSd_i becomes a negative value. Other points in FIG. 9 are the same as in FIG. 5, so the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

In the case of FIG. 9, the timing deviation .DELTA.t_i is positive and the timing deviation .DELTA.Sd_i is negative as described above, so the result is almost the same as the second example shown in FIG. That is, the timing deviation Δt_i is expressed by the above-described equation (4). Also, the timing deviation (-ΔSd_i) is defined by the above equation (5A). However, p=3 and q=2. As a result, an equation identical to equation (7) above is obtained.

Based on the timing deviation (-ΔSd_i), the current detection data on the A-end side can be interpolated so as to synchronize with the sample timing on the B-end side. For example, the current detection data on the A terminal side at time db22 can be obtained by linear approximation using the current detection value at time da23 and the current detection value at time da24. Specifically, let the current detection value at the A terminal at time da23 be Ia(da23), and let the current detection value at the A terminal at time da24 be Ia(da24). Let Ts be the sampling period of the current detection data at the A terminal. In this case, the current value Ia (db22) at the A terminal at time db22 is
Ia (db22)
= [(Ts+ΔSd2)·Ia(da23)−ΔSd2·Ia(da24)]/Ts
…(16)
is given by

(Summary of Examples 1 to 5: Timing Deviation Calculation)
As described above, in the present embodiment, the timing deviations Δt and ΔSd are defined to have different signs depending on whether the timing on the A-end side is behind or is ahead of the timing on the B-end side. .

Specifically, in the case of the above example, when the transmission time of the interpolated current data in the protection control device 60A on the A end side is later than the transmission time of the current detection data in the protection control device 60B on the B end side, the timing deviation Δt Make the value positive. In the opposite case, the value of the timing deviation Δt is made negative. Also, when the sample timing of the electrical quantity in the electrical quantity detection device 30A on the A end side lags behind the sampling timing of the electrical quantity in the electrical quantity detection device 30B on the B end side, the value of the timing deviation ΔSd is positive. . In the opposite case, the value of the timing deviation ΔSd is made negative.

By defining the timing deviations .DELTA.t and .DELTA.Sd as described above, the formulas for calculating the timing deviations .DELTA.t and .DELTA.Sd can be of the same form. Specifically, the timing deviation Δt_i for each transmission cycle can be obtained by the above equation (4). The timing deviation ΔSd_i for each transmission cycle can be obtained by the above equation (7).

[Interpolation calculation based on timing deviation ΔSd]
By interpolating the detected time-series current detection data using the timing deviation ΔSd of the sample timing, the current values sampled at the same time on the A end side and the B end side can be determined. A case of interpolating the current detection data on the A-end side in accordance with the sampling timing of the B-end side and a case of interpolating the current detection data on the B-end side in accordance with the sampling timing of the A-end side will be described below. In either case, it should be noted that the current value used for interpolation differs depending on the sign and magnitude of the timing deviation ΔSd. The former case has been described in Examples 1 to 4 above.

In the following description, it is assumed that the k-th sampling time da(k) on the A-end side corresponds to the k-th sampling time db(k) on the B-end side. Sampling times da(k) and db(k) are the same if the sampling timings on the A-end side and the B-end side are synchronized. Let Ts be the sampling cycle of each of the A-end side and the B-end side. As the sampling period Ts becomes shorter, the precision of the interpolated value by linear approximation improves.

(1. When interpolating current detection data on the A end side)
First, the case of interpolating the current detection data on the A-end side in accordance with the sample timing on the B-end side will be described. When Ts>ΔSd>0, the sampling time db(k) at the B end is between the sampling time da(k−1) and the sampling time da(k) at the A end. Therefore, the current value Ia[db(k)] at terminal A at time db(k) is the current value Ia(k-1) at terminal A at time da(k-1) and the current value Ia(k-1) at terminal A at time da(k). is obtained by an interpolation calculation using the current value Ia(k) of . Specifically, the current value Ia [db (k)] at the A terminal is
Ia [db(k)]
= [ΔSd・Ia(k−1)+(Ts−ΔSd)・Ia(k)]/Ts (17)
is given by

If −Ts<ΔSd<0, time db(k) is between time da(k) and time da(k+1). Therefore, the current value Ia[db(k) at the A terminal at time db(k) is the current value Ia(k) at the A terminal at time da(k) and the current value Ia(k) at the A terminal at time da(k+1) k+1) is obtained by an interpolation calculation using . Specifically, the current value Ia [db (k)] at the A terminal is
Ia [db(k)]
= [−ΔSd・Ia(k+1)+(Ts+ΔSd)・Ia(k)]/Ts (18)
is given by

(2. When interpolating current detection data on the B end side)
Next, the case of interpolating the current detection data on the B end side in accordance with the sample timing on the A end side will be described. First, when Ts>ΔSd>0, time da(k) is between time db(k) and time db(k+1). Therefore, the current value Ib[da(k)] at the B end at time da(k) is the current value Ib(k) at the B end at time db(k) and the current value Ib at the B end at time db(k+1) (k+1) and obtained by interpolation. Specifically, the current value Ib[da(k)] at the B end is
Ib[da(k)]
= [ΔSd・Ib(k+1)+(Ts−ΔSd)・Ib(k)]/Ts (19)
is given by

On the other hand, if −Ts<ΔSd<0, time da(k) is between time db(k−1) and time db(k). Therefore, the current value Ib at the B end at time da(k) is the current value Ib(k−1) at the B end at time db(k−1) and the current value Ib(k) at the B end at time db(k). ) is obtained by interpolation using Specifically, the current value Ib[da(k)] at the B end is
Ib[da(k)]
= [−ΔSd・Ib(k−1)+(Ts+ΔSd)・Ib(k)]/Ts (20)
is given by

[Execution timing of interpolation calculation and transmission timing of interpolation current data]
Next, the timing for executing the interpolation calculation and the timing for transmitting the interpolated current value as transmission data to the protection control device 60 at the other end will be described.

FIG. 10 is a diagram for explaining the timing of calculation and transmission of interpolated current values. The reception timing of current detection data and the transmission timing of transmission data in FIG. 10 are the same as in FIG. Therefore, in FIG. 10, the same reference numerals are given to the same or corresponding parts as in FIG. 5, and the description thereof will not be repeated.

As shown in FIG. 10, the current value Ib at the B terminal at reception timings db12, db22, db32, . On the other hand, the current value Ia at the A end corresponding to the reception timings db12, db22, db32, . . . of the current detection data at the B end is determined by interpolation calculation.

As described with reference to FIG. 5, in order to calculate the current Ia (db22) on the A terminal side at time db22, first, it is necessary to determine the timing deviation ΔSd2. Information on the time differences TS2 and SSd2 on the B-end side is required to calculate the timing deviation ΔSd2, and the protection control device 60A on the A-end side receives this information at the reception time ra2. The protection control device 60A on the A-end side completes the interpolation calculation of the current Ia (db22) after the reception time ra2 and before the transmission time ta3. Then, the protection control device 60A transmits the calculated interpolated current value Ia (db22) to the protection control device 60B on the B end side at the transmission time ta3.

Therefore, the protection control device 60A on the A-end side should make a fault judgment of the protection section after about one transmission cycle has passed since the current detection data on the B-end side was received from the protection control device 60B on the B-end side. can be done. On the other hand, the protection control device 60B on the B-end side can perform failure determination of the protection section using the interpolated current value on the A-end side received after one transmission period has elapsed.

FIG. 11 is a diagram for explaining calculation and transmission timing of the interpolated current value Ia(db32) in FIG. FIG. 11 schematically shows the current detection data in the A-end protection control device 60A. Let Ts be the sampling period in the electrical quantity detection device 30A on the A-end side.

As shown in FIG. 11, the timing deviation between the current detection data reception timing da32 at the A terminal and the current detection data reception timing db32 at the B terminal is calculated as ΔSd3. In this case, the interpolated current value Ia (db32) on the A terminal side at time db32 is obtained by using the current value Ia (da31) at time da31 and the current value Ia (da input converter 32) at time da32,
Ia (db32)
= [ΔSd3・Ia(da31)+(Ts−ΔSd3)・Ia(da32)]/Ts
…(twenty one)
is represented by

The calculation of the above equation (21) is performed after the information of the time differences TS3 and SSd3 on the B end side explained in FIG. 5 is received. Therefore, the interpolated current value Ia (db32) shown in the above equation (21) is calculated in the period between time ta4 and time ta5. Then, the calculated interpolated current value Ia (db32) is transmitted to the B terminal side at time ta5.

[Summary of operation of protection control system]
Hereinafter, the operation of the protection control system 200 described so far will be summarized using the flowcharts of FIGS. 12 and 13. FIG. Below, the block diagram of FIG. 3 will also be referred to as appropriate.

12 is a flow chart showing the operation of the transmission timing control unit in FIG. 3. FIG. In the present embodiment, control of the timing of transmitting transmission data from data transmitting section 113 is performed by protection control device 60A on the A terminal side.

At time ta_i, the data transmission unit 113 of the protection control device 60A transmits transmission data to the protection control device 60B on the B end side via the communication path 20 (step S110). At time ra_i, the data receiving unit 112 of the protection control device 60A receives the transmission data from the B end side via the communication path 20 (step S120).

In step S130, the timing deviation calculator 114 of the protection control device 60A calculates the time difference TM_i between the transmission time ta_i and the reception time ra_i as
TM_i=ra_i-ta_i (22)
Calculate according to

In the next step S140, timing deviation calculator 114 compares time difference TM_i with a predetermined lower limit value. When time difference TM_i is smaller than the lower limit value (YES in step S140), timing deviation calculation unit 114 advances the process to step S150. In step S150, the transmission timing control section 115 controls the data transmission section 113 to advance the transmission timing of the transmission data. For example, the means described with reference to FIGS. 4A and 4B are used.

When time difference TM_i is equal to or greater than the lower limit (NO in step S140), timing deviation calculator 114 compares time difference TM_i with a predetermined upper limit in step S160. When time difference TM_i exceeds the upper limit value (YES in step S160), timing deviation calculation unit 114 advances the process to step S170. In step S170, the transmission timing control section 115 controls the data transmission section 113 to delay the transmission timing of the transmission data. For example, the means described with reference to FIGS. 4A and 4B are used.

When the time difference TM_i is equal to or greater than the lower limit value and equal to or less than the upper limit value (NO in both steps S140 and S160), timing deviation calculation section 114 does not change the transmission timing of the transmission data.

This completes the processing in the transmission cycle starting from the transmission time ta_i. Next, protection control device 60A starts processing in the next transmission period starting from transmission time ta_i+1. Specifically, at time ta_i+1, the data transmission unit 113 of the protection control device 60A transmits transmission data to the protection control device 60B on the B end side via the communication path 20 (step S180). At time ra_i, the data receiving unit 112 of the protection control device 60A receives the transmission data from the B end side via the communication channel 20 (step S190). After that, the timing deviation calculation section 114 and the transmission timing control section 115 perform the same processing as described above.

13 is a flowchart showing the operation of the protection control system according to Embodiment 1. FIG. The flowchart of FIG. 13 shows the operation of the protection control devices 60A and 60B when Δt>0 and Ts>ΔSd>0 described in FIGS. The description so far will be summarized below mainly with reference to FIGS. 3 and 13. FIG.

In step S210 in FIG. 13, the protection control device 60A on the A-end side in FIG. 3 receives current detection data from the electric quantity detection device 30A (that is, MU) at time da_i_p. Similarly, in step S310, the protection control device 60B on the B end side receives current detection data from the electric quantity detection device 30B (ie, MU) at time db_i_q.

In the next step S220, the protection control device 60A on the A-end side transmits transmission data to the protection control device 60B on the B-end side at time ta_i. The transmission data in this case includes an interpolated current value Ia (db_i-2_q) calculated using the current detection value Ia received at time da_i-2_p. Further, the transmission data includes the time differences TM_i-1 and MSd_i-1 calculated one transmission period before.

On the other hand, in step S320, the protection control device 60B on the B end side transmits transmission data to the protection control device 60A on the A end side at time tb_i. The transmission data in this case includes the current value Ib (db_i_q) on the B terminal side received in step S310. Furthermore, the transmission data includes time differences TS_i-1 and SSd_i-1 calculated one transmission period before.

In the next step S230, the protection control device 60A on the A-end side receives the data transmitted from the protection control device 60B at time ra_i. Similarly, in step S330, the protection control device 60B on the B-end side receives the data transmitted from the protection control device 60A at time rb_i. The protection control device 60B on the B-end side uses the received interpolated current value Ia (db_i-2_q) on the A-end side and the corresponding detected current value Ia (db_i-2_q) on the B-end side to determine the current differential relay Execute the relay operation according to the method.

In the next step S240, the protection control device 60A on the A-end side calculates the time differences TM_i and MSd_i based on the current detection data reception time ta_i_p, the transmission data transmission time ta_i, and the data reception time ra_i from the B-end side. to calculate

Further, the protection control device 60A on the A-end side, based on the time differences TS_i-1, SSd_i-1 on the B-end side received in step S230 and the calculated time differences TM_i-1, MSd_i-1 on the A-end side, , timing deviations Δt_i−1 and ΔSd_i−1. Protection control device 60A uses timing deviation ΔSd_i−1 to calculate A end current value Ia(db_i−1_q) corresponding to B end side sample timing db_i−1_q. Relay calculation unit 117 of protection control device 60A performs relay calculation using calculated A terminal current value Ia (db_i-1_q) and B terminal current value Ib (db_i-1_q) already received from B terminal side. Run.

On the other hand, in step S340, the protection control device 60B on the B-end side calculates the time differences TS_i and SSd_i based on the current detection data reception time tb_i_q, the transmission data transmission time tb_i, and the data reception time rb_i from the B-end side. calculate. The protection control device 60B on the B end side does not perform interpolation calculation.

Thereafter, steps similar to steps S210 to S240 and steps S310 to S340 are repeated in the next transmission cycle. That is, steps S250 to S280 are the same as steps S210 to S240, except that the parameter i is replaced with i+1. Steps S350-S380 are the same as S310-S340 with parameter i replaced by i+1. It is as follows when it demonstrates concretely.

In step S250, the protection control device 60A on the A-end side receives current detection data from the electric quantity detection device 30A (that is, MU) at time da_i+1_p. Similarly, in step S350, the protection control device 60B on the B-end side receives current detection data from the electric quantity detection device 30B (that is, MU) at time db_i+1_q.

In the next step S260, the protection control device 60A on the A-end side transmits transmission data to the protection control device 60B on the B-end side at time ta_i+1. The transmission data in this case includes the interpolated current value Ia(db_i-1_q) calculated in step S240 and the time differences TM_i and MSd_i.

On the other hand, in step S360, the protection control device 60B on the B end side transmits transmission data to the protection control device 60A on the A end side at time tb_i+1. The transmission data in this case includes the current value Ib(db_i+1_q) on the B terminal side received in step S350. Furthermore, the transmitted data includes the time differences TS_i, SSd_i calculated in step S340.

In the next step S270, the protection control device 60A on the A-end side receives the data transmitted from the protection control device 60B at time ra_i+1. Similarly, in step S370, the protection control device 60B on the B end side receives the data transmitted from the protection control device 60A at time rb_i+1. The protection control device 60B on the B-end side uses the received interpolated current value Ia (db_i-1_q) on the A-end side and the corresponding detected current value Ia (db_i-1_q) on the B-end side to determine the current differential relay Execute the relay operation according to the method.

In the next step S280, the protection control device 60A on the A-end side sets the time difference TM_i+1, MSd_i+1 based on the reception time ta_i+1_p of the current detection data, the transmission time ta_i+1 of the transmission data, and the data reception time ra_i+1 from the B-end side. to calculate

Further, the A-side protection control device 60A calculates timing deviations Δt_i and ΔSd_i based on the time differences TS_i and SSd_i on the B-end side received in step S230 and the calculated time differences TM_i and MSd_i on the A-end side. do. The protection control device 60A uses the timing deviation ΔSd_i to calculate the A terminal current value Ia (db_i_q) corresponding to the sample timing db_i_q on the B terminal side. Relay calculation unit 117 of protection control device 60A performs relay calculation using calculated A terminal current value Ia (db_i_q) and B terminal current value Ib (db_i_q) already received from B terminal side.

On the other hand, in step S380, the protection control device 60B on the B-end side calculates the time differences TS_i+1 and SSd_i+1 based on the current detection data reception time tb_i+1_q, the transmission data transmission time tb_i+1, and the data reception time rb_i+1 from the B-end side. calculate. The protection control device 60B on the B end side does not perform interpolation calculation. Thereafter, the processing procedure in the next transmission period is similarly executed.

[Effect of Embodiment 1]
As described above, according to the protection control system 200 of the first embodiment, when protecting the protection section of the transmission line 21 by the current differential relay method, it is not necessary to synchronize the sample timing at each terminal of the protection section. . Also, synchronization of the protection controllers at each terminal of the protection section is not required. As a result, the system configuration of the protection control system 200 can be simplified because a common electric quantity detection device can be provided for each terminal in the protection section.

[Modification]
In the calculation of the timing deviation ΔSd, the time from the sampling of the electrical quantity by the electrical quantity detection device 30 to the reception of the A/D converted current detection data by the protection control device 60 is the A end side and the B end side. are assumed to be approximately equal. If the above time difference between the A end side and the B end side affects the accuracy of the protection calculation of the current differential relay system, the formula for calculating the timing deviation ΔSd in the above formula (7) is as follows. is changed to

Specifically, TRa is the delay time from when the electric quantity detection device 30A on the A-end side samples the current value until the protection control device 60A on the A-end side receives the A/D-converted current value. do. Similarly, let TRb be the delay time from when the electrical quantity detection device 30B on the B end side samples the current value until the protection control device 60B on the B end side receives the A/D-converted current value. . The formula for calculating the timing deviation ΔSd shown in formula (7) in this case is
ΔSd_i=Δt_i+SSd_i−MSd_i+TRb−TRa (23)
is changed as

Embodiment 2.
In the protection control system 200 of the first embodiment, one of the protection control devices 60 on the A-end side and the B-end side performs an interpolation operation on current detection data detected at its own end, and calculates current detection data after interpolation. to the protection control device 60 at the other end. The protection control system 200 of the second embodiment is configured such that the protection control device 60 of any terminal transmits current detection data detected at its own end to the other end. In this case, each protection control device 60 performs an interpolation operation on current detection data at one end. Even if modified as described above, the same effect as in the case of the first embodiment can be obtained. Description will be made below with reference to the drawings.

FIG. 14 is a flow chart showing the operation of the protection control system according to the second embodiment. The flowchart of FIG. 14 corresponds to the flowchart of FIG. Similar to the case of FIG. 13, it shows the operation of the protection control devices 60A and 60B when Δt>0 and Ts>ΔSd>0 described in FIGS. In each step of the flowchart of FIG. 14, the steps corresponding to those of the flowchart of FIG. 13 are given the same reference numerals.

Steps S210 and S310 in FIG. 14 are the same as in FIG. In the next step S220C, the protection control device 60A on the A-end side transmits transmission data to the protection control device 60B on the B-end side at time ta_i. The transmission data in this case does not include the interpolated current value, but includes the current detection value Ia (da_i_p) on the A terminal side received in step S210. In this respect, step S220C in FIG. 14 differs from step S220 in FIG. Further, the transmission data includes the time differences TM_i-1 and MSd_i-1 calculated one transmission period before.

On the other hand, in step S320, the protection control device 60B on the B end side transmits transmission data to the protection control device 60A on the A end side at time tb_i. The transmission data in this case includes the current value Ib(db_i_q) on the B terminal side received in step S310, as in the case of FIG. Furthermore, the transmission data includes time differences TS_i-1 and SSd_i-1 calculated one transmission period before.

In the next step S230, the protection control device 60A on the A-end side receives the data transmitted from the protection control device 60B at time ra_i. Similarly, in step S330, the protection control device 60B on the B-end side receives the data transmitted from the protection control device 60A at time rb_i.

In the next step S240, the protection control device 60A on the A-end side calculates the time differences TM_i and MSd_i based on the current detection data reception time ta_i_p, the transmission data transmission time ta_i, and the data reception time ra_i from the B-end side. to calculate

Further, the protection control device 60A on the A-end side, based on the time differences TS_i-1, SSd_i-1 on the B-end side received in step S230 and the calculated time differences TM_i-1, MSd_i-1 on the A-end side, , timing deviations Δt_i−1 and ΔSd_i−1. Protection control device 60A uses timing deviation ΔSd_i−1 to calculate A end current value Ia(db_i−1_q) corresponding to B end side sample timing db_i−1_q. Relay calculation unit 117 of protection control device 60A performs relay calculation using calculated A terminal current value Ia (db_i-1_q) and B terminal current value Ib (db_i-1_q) already received from B terminal side. Run.

On the other hand, in step S340C, the protection control device 60B on the B-end side calculates the time differences TS_i and SSd_i based on the current detection data reception time tb_i_q, the transmission data transmission time tb_i, and the data reception time rb_i from the B-end side. calculate.

Furthermore, the protection control device 60B on the B-end side, based on the time differences TM_i-1 and MSd_i-1 on the A-end side received in step S330 and the calculated time differences TS_i-1 and SSd_i-1 on the B-end side, , timing deviations Δt_i−1 and ΔSd_i−1. Protection control device 60B uses timing deviation ΔSd_i−1 to calculate B end current value Ib(da_i−1_p) corresponding to A end sample timing da_i−1_p. Relay calculation unit 117 of protection control device 60B performs relay calculation using calculated terminal B current value Ib(da_i−1_p) and terminal A current value Ia(da_i−1_p) already received from terminal A. Run.

The next steps S250 and S350 are the same as in FIG. In the next step S260C, the protection control device 60A on the A-end side transmits transmission data to the protection control device 60B on the B-end side at time ta_i+1. The transmission data in this case includes the current detection value Ia (da_i+1_p) on the A terminal side received in step S250. Additionally, the transmitted data includes the time differences TM_i and MSd_i calculated in step S240.

On the other hand, in step S360, the protection control device 60B on the B end side transmits transmission data to the protection control device 60A on the A end side at time tb_i+1. The transmission data in this case includes the current value Ib(db_i+1_q) on the B terminal side received in step S350. Furthermore, the transmitted data includes the time differences TS_i, SSd_i calculated in step S340.

In the next step S270, the protection control device 60A on the A-end side receives the data transmitted from the protection control device 60B at time ra_i+1. Similarly, in step S370, the protection control device 60B on the B end side receives the data transmitted from the protection control device 60A at time rb_i+1.

In the next step S280, the protection control device 60A on the A-end side sets the time difference TM_i+1, MSd_i+1 based on the reception time ta_i+1_p of the current detection data, the transmission time ta_i+1 of the transmission data, and the data reception time ra_i+1 from the B-end side. to calculate

Further, the A-side protection control device 60A calculates timing deviations Δt_i and ΔSd_i based on the time differences TS_i and SSd_i on the B-end side received in step S270 and the calculated time differences TM_i and MSd_i on the A-end side. do. The protection control device 60A uses the timing deviation ΔSd_i to calculate the A terminal current value Ia (db_i_q) corresponding to the sample timing db_i_q on the B terminal side. Relay calculation unit 117 of protection control device 60A performs relay calculation using calculated A terminal current value Ia (db_i_q) and B terminal current value Ib (db_i_q) received from B terminal side in step S230.

On the other hand, in step S380C, the protection control device 60B on the B-end side calculates the time differences TS_i+1 and SSd_i+1 based on the current detection data reception time tb_i+1_q, the transmission data transmission time tb_i+1, and the data reception time rb_i+1 from the B-end side. calculate.

Further, the protection control device 60B on the B-end side calculates timing deviations Δt_i and ΔSd_i based on the time differences TM_i and MSd_i on the A-end side received in step S330 and the calculated time differences TS_i and SSd_i on the B-end side. do. The protection control device 60B uses the timing deviation ΔSd_i to calculate the B end current value Ib(da_i_p) corresponding to the sample timing da_i_p on the A end side. Relay calculation unit 117 of protection control device 60B performs relay calculation using the calculated B end current value Ib(da_i_p) and the A end current value Ia(da_i_p) received from the A end side in step S330. Thereafter, processing in the next transmission cycle is executed in the same procedure.

Embodiment 3.
In the third embodiment, a multi-terminal power transmission line to be protected will be described. The protection control systems of Embodiments 1 and 2 can also be applied to transmission lines with multiple terminals, and provide similar effects. Although the case of three terminals will be described below, the same applies to transmission lines having four or more terminals.

FIG. 15 is a diagram for explaining the operation of the protection control system when the protection section has three terminals. FIG. 15A shows a schematic configuration of a power system.

Referring to FIG. 15A, A-end substation 100A, B-end substation 100B, and C-end substation 100C are provided at respective terminals of transmission line 21 (21A, 21B, 21C). The A-end substation 100A includes an electric quantity detection device 30A and a protection control device 60A. The B-end substation 100B includes an electric quantity detection device 30B and a protection control device 60B. The substation C-end substation 100C includes an electric quantity detection device 30C and a protection control device 60C.

The A-end electrical quantity detection device 30A detects the current value at the A-end of the transmission line 21 at a predetermined sampling cycle, and transmits the detected A-end current value to the A-end protection control device 60A. The B-end electrical quantity detection device 30B detects the current value at the B-end of the transmission line 21 at a predetermined sampling cycle, and transmits the detected B-end current value to the B-end protection control device 60B. The C-end electrical quantity detection device 30C detects the current value at the C-end of the power transmission line 21 at a predetermined sampling cycle, and transmits the detected C-end current value to the C-end protection control device 60C.

The protection control device 60A at the A end and the protection control device 60B at the B end are interconnected via a communication path 20AB, and exchange current detection data and the like via the communication path 20AB. The protection control device 60B at the B end and the protection control device 60C at the C end are interconnected via a communication path 20BC, and exchange current detection data and the like via the communication path 20BC. The protection control device 60C at the C end and the protection control device 60A at the A end are interconnected via a communication path 20CA, and exchange current detection data and the like via the communication path 20CA.

In the protection control system configured as described above, each protection control device 60 operates in the same manner as described in the first and second embodiments. Thereby, the protection control devices 60A and 60B detect the timing deviation ΔSd_ab between the reception timing da of the current detection data at the A terminal and the reception timing db of the current detection data at the B terminal. The protection control devices 60B and 60C detect a timing deviation ΔSd_bc between the reception timing db of the current detection data at the B terminal and the reception timing dc of the current detection data at the C terminal. The protection control devices 60C and 60A detect a timing deviation ΔSd_ca between the current detection data reception timing dc at the C terminal and the current detection data reception timing da at the A terminal.

FIG. 15B is a timing chart showing the relationship between the timing deviations ΔSd_ab, ΔSd_bc, and ΔSd_ca detected by each protection control device 60. As shown in FIG. For example, with reference to the reception timing at the A terminal, which has the earliest reception timing of the current detection data (and therefore the earliest sampling timing), the B terminal current value and the C current value corresponding to the time da can be obtained by interpolation. can be done. Thus, as in the first and second embodiments, it is possible to protect the transmission line 21 by the current differential relay method.

The embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

20 communication path, 21 transmission line, 25 reference signal generator, 26 voltage transformer, 27 current transformer, 30 electric quantity detector, 60, 80 protection control device, 100A, 100B substation, 110 data receiver, 111 data storage unit 114 timing deviation calculation unit 116 interpolation calculation unit 117 relay calculation unit TMS2 timing signal 200 protection control system CLK1 to CLK6 clock circuit MSd, SSd, TM, TS time difference Ref1, Ref2 reference signal T Data transmission period, Td transmission delay time, Ts sampling period, Δt timing deviation, ΔSd timing deviation.

Claims (6)

A protection control system for protecting a protected section of a transmission line, comprising:
a first electrical quantity detection device provided at a first end of the protection section and configured to generate first current detection data by sampling the current of the transmission line at a first sampling period;
a first protection control device provided at the first end for outputting first transmission data based on the first current detection data to a communication path at a first transmission cycle;
a second electric quantity detection device provided at a second end of the protection section and configured to generate second current detection data by sampling the current of the transmission line at a second sampling period;
provided at the second end, connected to the first protection control device via the communication path, and transmitting second transmission data based on the second current detection data to the communication path at a second transmission cycle; A second protection control device that outputs,
the first sampling period, the first transmission period, the second sampling period, and the second transmission period are asynchronous with each other;
The first protection control device receives the first current detection data from the first electric quantity detection device and transmits the first transmission data for each first transmission cycle. measuring a first time difference and a second time difference from transmitting the first transmission data to receiving the second transmission data;
The second protection control device receives the second current detection data from the second electric quantity detection device and transmits the second current detection data every second transmission cycle. and a fourth time difference from the transmission of the second transmission data to the reception of the first transmission data;
At least one of the first protection and control device and the second protection and control device is automatically controlled based on the first time difference, the second time difference, the third time difference, and the fourth time difference. A protection control system that interpolates end-side current detection data and determines whether or not a fault occurs in the protection section based on comparison between the interpolated current detection data and the other end's current detection data. The first protection control device adjusts the timing of transmitting the first transmission data so that the second time difference is between a lower limit value larger than 0 and an upper limit value smaller than the first transmission cycle. 2. The protection control system of claim 1, controlling. At least one of the first protection and control device and the second protection and control device,
calculating a first timing deviation, which is a time difference between the transmission timing of the first transmission data and the transmission timing of the second transmission data, based on the second time difference and the fourth time difference;
A second time difference, which is the time difference between the sampling timing of the first current detection data and the sampling timing of the second current detection data, based on the first time difference, the third time difference, and the first timing deviation. Calculate the timing deviation of
3. The protection control system according to claim 1 or 2, configured to interpolate the self-end current sensing data based on the second timing deviation. 4. The protection and control system of claim 3, wherein said first timing deviation is determined by dividing by two the difference between said second time difference and said fourth time difference. 5. The protection control system according to claim 4, wherein said second timing deviation is determined based on a difference between said first time difference and said third time difference plus said first timing deviation. A third electric current detection device provided at the first end for performing a relay operation based on the current detection data detected by the first electric quantity detection device in a method different from the method used in the first protection control device. a protective control device for
A fourth device which is provided at the second end and performs relay calculation based on the current detection data detected by the second electric quantity detection device in a method different from the method used in the second protection control device. The protection and control system according to any one of claims 1 to 5, further comprising a protection and control device.

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