CN108983036A - A kind of travelling wave ranging system based on electronic mutual inductor - Google Patents

Abstract

The invention relates to a traveling wave ranging system based on an electronic transformer, which includes a ranging host and at least one acquisition device, the acquisition device includes an electronic transformer and an acquisition module, each acquisition module has an SV data transmission port, and the measurement The corresponding SV data receiving port on the distance host is connected to send the collected real-time SV sampling information to the ranging host as a basis for judging the occurrence of a fault; each acquisition module has an Ethernet port, which corresponds to the corresponding SV on the ranging host. Ethernet port connection, when a fault occurs, the ranging host sends a calling message to the corresponding acquisition module through the Ethernet port, and the acquisition module sends the required fault recording message to the ranging host through the Ethernet port for traveling wave ranging. Compared with the traveling wave ranging system based on traditional transformers, the accuracy and reliability of the ranging system have been greatly improved.

Description

A Traveling Wave Ranging System Based on Electronic Transformer

technical field

The invention relates to a traveling wave ranging system based on an electronic transformer, and belongs to the technical field of traveling wave ranging based on an electronic transformer.

Background technique

High-voltage transmission line is an important part of the power system. It is responsible for the important responsibility of electric energy transportation. Since AC-DC transmission projects generally have long lines and complex terrains, it is also the link most prone to failure in the technical power system. It is extremely difficult to find line faults, and accurate distance measurement is important. The function of the transmission line distance measuring system is to accurately calculate the location of the fault point after the line fault occurs, so that the operator can quickly find out the cause of the short circuit at the fault point, timely and accurately locate the fault and repair the fault line, so as to ensure the safety of the transmission line. power supply reliability. With the gradual maturity of related technologies such as traveling wave signal extraction, high-speed data acquisition, and data transmission, a variety of traveling wave fault location systems have been successfully developed, and a variety of traveling wave fault location devices have been put into actual operation at home and abroad.

The traveling wave ranging system can complete the location of fault points, and is widely used in fault diagnosis and fault location of smart substations. At present, domestic traveling wave ranging systems are basically based on traditional transformers. Traditional transformers currently have disadvantages such as difficult insulation, small dynamic range, poor safety, large volume, and high cost. Electronic transformers are the future development direction. In particular, electronic current transformers based on Rogowski coils are now very mature. Compared with traditional current transformers, they have higher measurement accuracy and better dynamic range, which can greatly improve the distance measurement accuracy and also conform to future development. direction. However, the traveling wave ranging system based on electronic transformers requires special data acquisition and data transmission methods to meet the requirements of high speed and intelligence. Therefore, due to factors such as structure and ranging methods, the traditional ranging system cannot It is suitable for electronic transformers, and the study of distributed traveling wave ranging systems based on electronic transformers is of great significance for improving the accuracy, reliability and high speed of traveling wave ranging.

Contents of the invention

The object of the present invention is to provide a traveling wave distance measuring system based on electronic transformers to solve the problem that electronic transformers cannot be used in traditional distance measuring systems.

To achieve the above object, the solution of the present invention includes: a traveling wave ranging system based on an electronic transformer, characterized in that it includes a ranging host and at least one acquisition device, and the acquisition device includes an electronic transformer and an acquisition device. module, each acquisition module has an SV data transmission port, which is connected to the corresponding SV data receiving port on the ranging host, and is used to send the collected real-time SV sampling information to the ranging host as a basis for judging the occurrence of a fault; each acquisition There is an Ethernet port on the module, which is connected to the corresponding Ethernet port on the ranging host. When a fault occurs, the ranging host sends a calling message to the corresponding acquisition module through the Ethernet port, and the acquisition module sends a call message to the ranging host through the Ethernet port. The host sends the required fault recording message for traveling wave ranging.

There is also a synchronous signal receiving port on each acquisition module, which is connected to the synchronous signal sending port on the ranging host, and the ranging host sends a synchronous sampling time message to each acquisition module for synchronizing each acquisition module.

There is a synchronization signal sending port on the ranging host, and an optical extension module is connected to the output of the synchronization signal sending port, and the optical extension module is correspondingly connected to the synchronization signal receiving ports of each acquisition module.

There is time stamp information in the synchronous sampling time message sent by the ranging host to each acquisition module, and each acquisition module divides the time stamp information to ensure time synchronization with the ranging host.

The acquisition module is an SOC chip based on ARM+FPGA architecture.

The acquisition module includes an ADC acquisition port for connecting the electronic transformer, and the FPGA includes an acquisition processing logic unit, which is connected to the DDR RAM, and is used to write the collected fault recording message into the cache of the DDR RAM Space, the cache space of DDR RAM is shared with ARM, ARM sends the fault recording message to the ranging host through the corresponding Ethernet port, and the acquisition and processing logic unit sends real-time SV sampling information to the ranging host through the corresponding SV data transmission port host.

Before performing frequency division on the time stamp information, the acquisition module judges the validity of the received time stamp information, and performs the frequency division processing when the received time stamp information is valid.

The validity judgment process of timestamp information includes the following steps:

(1) While receiving the timestamp information, the local clock of the acquisition module starts counting;

(2) If the time measured by the local clock is greater than the sending interval of the timestamp, it is determined that the timestamp information is invalid; otherwise, it is determined that it is valid.

If the error between the time information in the previous frame time stamp and the time information in the current frame time stamp is greater than a set value, it is judged that the current frame time stamp information is invalid.

The traveling wave ranging system provided by the present invention is an electronic current transformer based on the Rogowski coil principle, which can more realistically respond to a fault waveform and has higher ranging accuracy. Moreover, a distributed architecture is adopted, and a traveling wave ranging host Receiving relevant sampling messages from one or more traveling wave ranging acquisition devices, the number of acquisition devices can be set flexibly, making the site layout more flexible. There are two kinds of data transmission ports on the ranging host, namely the SV data receiving port and the Ethernet port. The SV data receiving port is connected to the SV data transmission port on each acquisition module. The SV data transmission port is sent to the ranging host, and the ranging host processes the SV data to determine whether a fault occurs; the Ethernet port is connected to the Ethernet port on each acquisition module, and when a fault occurs, the ranging host passes the Ethernet port. The network port sends a calling message to the corresponding acquisition module, and the acquisition module sends the required fault recording message to the ranging host through the Ethernet port, and the ranging host performs logical judgment of traveling wave ranging according to the fault recording message. Therefore, the distance measurement system uses two kinds of data transmission ports to judge the fault startup and fault distance measurement. Compared with the traveling wave distance measurement system based on traditional transformers, the accuracy and reliability have been greatly improved. The distance system is suitable for the special requirements of electronic transformers, which is of great significance for improving the accuracy, reliability and high speed of traveling wave ranging.

Description of drawings

Figure 1 is a schematic diagram of the traveling wave ranging system;

Fig. 2 is the process diagram of the synchronous message that the acquisition unit receives the ranging host;

Fig. 3 is a schematic diagram of the software architecture of the acquisition unit;

Fig. 4 is a logic diagram of data interaction between the acquisition device and the ranging host.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The traveling wave ranging system mainly includes two parts, namely the traveling wave ranging host and the slave. The sub-machine is composed of at least one acquisition device, and the installation method of the traveling wave ranging host and the sub-machine is shown in Figure 1. For any acquisition device, it includes two parts, namely the electronic transformer based on the Rogowski coil principle and the high-speed acquisition unit for traveling wave ranging (also known as the high-speed acquisition module for traveling wave ranging, hereinafter referred to as the acquisition unit), the acquisition unit It adopts a three-phase integrated design and is installed on-site with the electronic current transformer, which can collect A, B, and C three-phase current information of a single line. The acquisition device in the traveling wave ranging system may be called a distributed acquisition device, and the acquisition unit in the acquisition device may also be called a distributed acquisition unit. The number of collection devices is set according to actual requirements. In this embodiment, a single distance measuring host can support a maximum of 8 collection devices.

There are three data ports on the traveling wave ranging host, namely: SV data receiving port, Ethernet port and synchronous signal sending port, respectively corresponding to the point-to-point SV port, 100M Ethernet port and synchronous port TX in Figure 1; the acquisition unit There are three data ports on it, namely: SV data transmission port, Ethernet port and synchronous signal receiving port, corresponding to the SV point-to-point port in Figure 1, 100M Ethernet port and synchronous port RX. The number of point-to-point SV ports and 100M Ethernet ports on the ranging host is the same as the number of acquisition units in the system, and the SV point-to-point ports on each acquisition unit are connected to the point-to-point SV ports on the ranging host. The 100M Ethernet ports on each acquisition unit are connected to the 100M Ethernet ports on the ranging host in one-to-one correspondence. In fact, both the point-to-point SV port and the 100M Ethernet port on the ranging host are conventional Ethernet ports. However, since these two ports have different functions, one of them is called point-to-point for ease of explanation. SV port, the other is called 100M Ethernet port; correspondingly, the SV data transmission port and Ethernet port on the acquisition unit are also Ethernet ports.

Through the point-to-point SV port on the traveling wave ranging host and the SV point-to-point port on the acquisition unit, the acquisition unit sends the collected real-time SV sampling information to the traveling wave ranging host. In this embodiment, the acquisition unit sends real-time The 80-point real-time SV sampling information is used as the basis for judging the occurrence of faults; the 100M Ethernet port on the traveling wave ranging host and the recorded wave on the acquisition unit are sent to the 100M Ethernet port to realize when a fault occurs, the measurement The distance host sends a call message to the corresponding acquisition unit through the Ethernet port, and the acquisition unit sends the required fault recording message to the ranging host through the Ethernet port after receiving the call message. In this embodiment, what is sent is 2M When the sampling rate is faulty, the wave message is recorded for traveling wave ranging.

Moreover, in order to realize the sampling synchronization between the traveling wave ranging host and each acquisition unit, the traveling wave ranging host is also provided with a synchronization signal sending port, and each acquisition unit is provided with a synchronization signal receiving port, and the synchronization signal sending port is connected with each acquisition unit. The sync signal receiving port on the corresponding connection. Further, in order to reduce the number of synchronous signal sending ports of the traveling wave ranging host, only one synchronizing signal sending port is set on the traveling wave ranging host, corresponding to the synchronous port TX in Fig. The TX output is connected with an optical extension device, which is connected to the synchronization signal receiving port of each acquisition unit corresponding to the synchronization port RX in Figure 1, so the optical extension device is an interface expansion device. The traveling wave ranging host sends a synchronous sampling time message through the synchronous port TX. After passing through the optical expansion device, the synchronous sampling time message is sent to each acquisition unit for the sampling synchronization of each acquisition unit, realizing the synchronization between data acquisition and transmission. Precise control.

After verification, if the second pulse or B code frequency division mode is used, but because of the difference in crystal oscillator count value between the traveling wave ranging host and each acquisition unit (the error of the general crystal oscillator is 10-20ppm), the error per second can reach A few to ten microseconds, so the ordinary second pulse and B code synchronization method is difficult to meet the minimum synchronization sampling accuracy of 500nS, so the method of synchronous sampling information sent by the traveling wave ranging host is used to synchronize the sampling. Because there is no specific time information in the original synchronous sampling time message, the mode of sending the synchronous time stamp is optional, that is, the time stamp information is added to the synchronous sampling time message. In order to ensure the accuracy of the time stamp, the higher the sending frequency of the time stamp, the better. At the same time, each acquisition unit must ensure a certain punctuality function, divide the frequency between the time stamps, and time stamp the sampling points. The sending interval of the time stamp is 250uS, and the baud rate is 2M. The acquisition unit divides the time stamp in the interval of the time stamp to ensure the time synchronization with the traveling wave ranging host. The time synchronization messages of the traveling wave ranging host and each acquisition unit are shown in Table 1. The time information is a 32-bit time stamp, automatically flipped, and the unit is 10nS.

Table 1

Its synchronization mode is shown in Figure 2. The acquisition unit receives the synchronization time stamp sent by the traveling wave ranging host, and judges the validity of the time stamp through certain logic. Use the following methods to judge the validity of the timestamp information sent by the host:

In the first step, the acquisition unit parses the time stamp UART_T _cnt sent by the host. At the same time, the local clock of the acquisition unit produces a clock counter by itself and starts timing. The count value of the clock counter, that is, the time obtained by timing is t _cnt , and the counter is automatically cleared when the rising edge of the second pulse arrives.

The second step is to judge the count value t _cnt . If the count value t _cnt is greater than the transmission interval t _T of the timestamp, that is, t _cnt exceeds a certain threshold range greater than 0 in the transmission interval of the timestamp. If expressed by inequality, it is: |t _cnt -t _T |>offset, offset is the above-mentioned threshold range set, then it is judged that the time stamp is invalid, that is, the validity flag of the time stamp TIME_VALID=0; otherwise, it is judged as valid.

In this embodiment, since the timestamp is 32 bits, the sending interval t _T of the timestamp is 250uS, and the offset is 10uS as an example, then, if |t _cnt -250uS|>10uS, then TIME_VALID=0.

On the basis of the above criteria, the validity can be further judged according to the time information in the previous frame time stamp and the time information in the current frame time stamp. If the error between the time information in the previous frame timestamp and the time information in the current frame timestamp is greater than a set value (such as 10uS), it means that the time information of the two frame timestamps is very different, then it is judged as Current frame timestamp information is invalid. Assuming that the time information in the previous frame timestamp is LAST_UART_T _cnt , and the time information in the current frame timestamp is UART_T _cnt , then calculate the absolute value of the time information difference between the previous frame timestamp and the current frame timestamp|LAST_UART_T _cnt -UART_T _cnt |, if the absolute value is greater than a set value, set TIME_VALID to 0, that is, invalid.

If the received timestamp information is valid, divide the timestamp and use the timestamp to update the local time T _cnt , T _cnt <= UART_T _cnt , otherwise T _cnt will be self-timely accumulated, that is, T _cnt <= T _cnt + 1.

Each sampling unit needs to record the time stamp of its sampling time. The actual time T _{acquisition unit} is the local time stamp T _{host of the traveling wave ranging host} plus the delay time T _delay for sending messages. The calculation formula is:

T _{acquisition unit} = T _host + T _delay

The traveling wave ranging host sends time stamps to the acquisition unit to achieve 10nS high-precision sampling synchronization between different acquisition units, and between the acquisition unit and the traveling wave ranging host. With the high-speed sampling rate of 2M/S, the final Achieve a ranging accuracy of 150m.

In this embodiment, the main control used by the acquisition unit is the industry scalable processing platform ZYNQ launched by Xilinx, the model is 7Z010, which is an SOC chip based on the ARM+FPGA architecture and has powerful digital signal processing Function.

As shown in Figure 3, in addition to ARM+FPGA, the acquisition unit also has related communication interfaces, such as: high-speed ADC acquisition port, optical Ethernet port 1, optical Ethernet port 2, optical time synchronization interface and other interfaces. Among them, the optical Ethernet port 1 is used to send fault recording messages, which corresponds to the 100M Ethernet port for sending the recorded waves in Figure 1; the optical Ethernet port 2 is used to send real-time SV sampling information, which corresponds to Figure 1 The SV point-to-point port; the optical time synchronization interface is used to receive synchronization information, corresponding to the synchronization port RX in Figure 1; the high-speed ADC acquisition port is connected to the electronic transformer for receiving the collection information of the electronic transformer.

The core of the acquisition unit lies in ARM and FPGA, wherein the PS unit (processor system unit) in Figure 3 corresponds to ARM, and the PL unit (programmable logic unit) corresponds to FPGA. The FPGA includes an acquisition and processing logic unit for data related processing. The acquisition and processing logic unit is connected to the DDR RAM, and further connected to the DDR RAM through the AXI HP interface. Write to the cache space of DDR RAM, and AXIHP transfers data with DDR RAM through DMA, which has high efficiency and fast speed, and does not occupy CPU resources. The buffer space of the DDR RAM is shared with the ARM, and the ARM communicates with the traveling wave ranging host through the optical Ethernet port 1 to confirm the timing of sending the message, and then packs and sends the fault recording message to the traveling wave ranging host. In addition, the acquisition unit can use the acquisition and processing logic unit to send the real-time sampling message in SV format with a single-cycle sampling rate of 80 points to the traveling wave ranging host through the optical Ethernet port 2 through the sampling method, and start as the host to judge the fault basis. In addition, the acquisition unit uses a large-capacity buffer to store 10 cycles of 2M/S high-speed fault recording messages, that is, the data window of the fault recording message is 10 cycles. When the line fails, the acquisition unit receives the traveling wave Called by the ranging host, send the wave recording information of 3 cycles of fault time to the traveling wave ranging host as the basis for logical judgment of traveling wave ranging. In addition, since the wave recording message needs to be used for traveling wave ranging, in order to achieve rapid ranging, the transmission rate of the wave recording message is usually faster than the transmission rate of the real-time SV sampling message.

Therefore, in the ranging system, the acquisition unit sends the real-time SV sampling message to the ranging host, and the ranging host judges the fault start based on the sampling message. When measuring the distance, send the corresponding data call message to the acquisition unit through the Ethernet, the acquisition unit responds, and sends the wave recording message at the time of failure. The traveling wave ranging host receives the recorded wave message and judges the sequence number of the message. After receiving the recorded wave message, the ranging host sends a response to the acquisition unit to complete the process of sending the traveling wave ranging data. , and its principle is shown in Figure 4. The distance measuring host performs traveling wave distance measurement according to the received fault recording message to improve system stability. Since the judgment of fault startup and the judgment of traveling wave ranging belong to the prior art, this embodiment will not describe these two judgment processes in detail.

Specific embodiments have been given above, but the present invention is not limited to the described embodiments. The basic idea of the present invention lies in the above-mentioned basic scheme. For those of ordinary skill in the art, according to the teaching of the present invention, it does not need to spend creative labor to design various deformation models, formulas, and parameters. Changes, modifications, substitutions and variations to the implementations without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (9)

1. A traveling wave ranging system based on an electronic transformer, characterized in that it comprises a ranging host and at least one acquisition device, and the acquisition device comprises an electronic transformer and an acquisition module, and SV data is arranged on each acquisition module The transmission port is connected to the corresponding SV data receiving port on the ranging host, and is used to send the collected real-time SV sampling information to the ranging host as a basis for judging the occurrence of faults; each acquisition module has an Ethernet port, which is connected to the measuring The distance measuring host is connected to the corresponding Ethernet port. When a fault occurs, the ranging host sends a calling message to the corresponding acquisition module through the Ethernet port, and the acquisition module sends the required fault recording message to the ranging host through the Ethernet port. , for traveling wave ranging. 2. The traveling wave ranging system based on electronic transformer according to claim 1, characterized in that, each acquisition module also has a synchronous signal receiving port, which is connected with the synchronous signal sending port on the ranging host, and the ranging The host sends a synchronous sampling time message to each acquisition module for synchronizing each acquisition module. 3. The traveling wave distance measuring system based on electronic transformer according to claim 2, characterized in that, there is a synchronous signal sending port on the said ranging host, and the output of said synchronous signal sending port is connected with an optical extension module, and the optical expansion module is correspondingly connected to the synchronous signal receiving port of each acquisition module. 4. The traveling wave ranging system based on electronic transformers according to claim 2, characterized in that, the synchronous sampling time message sent by the ranging host to each acquisition module has timestamp information, and each acquisition module compares the time The stamp information is frequency-divided to ensure time synchronization with the ranging host. 5. The traveling wave ranging system based on electronic transformer according to claim 1 or 2, wherein the acquisition module is an SOC chip based on ARM+FPGA architecture. 6. The traveling wave ranging system based on electronic transformer according to claim 5, wherein the acquisition module includes an ADC acquisition port for connecting the electronic transformer, and the FPGA includes a collection processing logic unit, which collects The processing logic unit is connected with the DDR RAM, and is used to write the collected fault recording messages into the buffer space of the DDR RAM. The buffer space of the DDR RAM is shared with the ARM, and the ARM sends the fault recording messages through the corresponding Ethernet port For the ranging host, the collection and processing logic unit sends the real-time SV sampling information to the ranging host through the corresponding SV data transmission port. 7. The traveling wave ranging system based on electronic transformers according to claim 4, wherein the acquisition module performs a validity judgment on the received timestamp information before performing frequency division on the timestamp information, when When the received time stamp information is valid, the frequency division processing is performed. 8. The traveling wave ranging system based on electronic transformers according to claim 7, wherein the validity judgment process of time stamp information comprises the following steps: (1) While receiving the timestamp information, the local clock of the acquisition module starts counting; (2) If the time measured by the local clock is greater than the sending interval of the timestamp, it is determined that the timestamp information is invalid; otherwise, it is determined that it is valid. 9. The traveling wave ranging system based on electronic transformers according to claim 8, wherein if the error between the time information in the previous frame timestamp and the time information in the current frame timestamp is greater than a set value, it is judged that the timestamp information of the current frame is invalid.