JPH01302939A - Sampling time synchronization system - Google Patents

Abstract

PURPOSE:To accurately coincide sampling timings in respective terminal stations in simple constitution and without adjustment by transmitting a timing reference signal at every prescribed time with respect to plural transmission paths whose transmission directions are opposite. CONSTITUTION:Timing reference signals which have been transmitted from respective master terminal stations 2 to respective transmission paths make a round of respective data terminal stations 3, 4 and 5, and they return. Namely, two signals outputted from the terminal station 2 are transmitted to respective transmission paths at the same time TS and they return after they go round all the terminal stations. Since two transmission lines are in a linear symmetrical relation with a central line PQ as an axis in such a case, the intermediate time (TR+TL)/2 of reception times TR and TL always coincide when the reception timings of clockwise and counterclockwise transmission signals in respective terminal stations are set to TR and TL. Respective terminal stations measure the timings TR and TL and control the sampling timings with the intermediate time as reference, whereby the sampling timing in all the data terminal stations can accurately be coincident without adjustment.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention connects a plurality of terminal stations through a transmission path and collects synchronized Zang-linked information at each terminal station.

This paper relates to a sampling time synchronization method in a processing system, and is particularly applied to a grid electricity quantity collection system for current differential protection of a power grid.

(Prior Art) FIG. 8 shows an example of a configuration in which a current differential relay system is used to protect a power transmission line at another terminal.

In Fig. 8, 1 is a power transmission line, 2, 3, 4, and 5 are data terminal stations provided at branch terminals of the power transmission line and collect current data at each terminal, and 101 is a current at each terminal at each data master station. 12.13.14.15 is a transmission line connecting data terminal stations in a loop; 6 is a transmission line for collecting data from data terminal stations 2, 3, 4.5; 12.13° 14, 15 shows a relay calculation terminal that performs current differential protection calculation based on the current data of each terminal transmitted.

The operation of this conventional example will be described below based on an example of a data format on a transmission path shown in FIG.

In FIG. 9, TX2, 3.4.5 indicate data transmitted by data terminal stations 2, 3, 4.5, respectively, and t12.
t13. t14 indicates the transmission delay time between each data terminal station.

In addition, to Indicates a sampling synchronization flag.

In the conventional example shown in FIG. 8, the data terminal station 2 acts as a master station and sends out a signal containing a sampling synchronization flag SF at regular intervals. The transmission signal TX2 including the sampling synchronization flag SF is received by the data terminal station 3 via the transmission line 12. The data terminal station 3 detects the sampling synchronization flag SF in the received data, controls the sampling timing of its own station accordingly, and adds current data IB sampled and encoded by its own station to the received signal TX2. and sends it out as a transmission signal TX3. The signal TX3 transmitted from the data terminal station 3 is received by the terminal station 4 through the transmission line 13, and is sent out after being added with a current data IC like the terminal station 3 described above. Similarly, the data passing through the data terminal station 5 finally returns to the data terminal station 2 with all the current data collected by the data terminal stations 2, 3, 4.5 taken in.

The data terminal station 2 sends the current data collected by each data terminal station included in the returned received signal to the relay calculation terminal station 6.

The relay calculation terminal 6 performs current differential calculation based on the current data, and outputs a trip command to the data terminal 2 when a fault is detected in the system. The data terminal station 2 includes the trip signal received from the relay calculation terminal station 6 in the next sampling transmission data TX2, and transmits it to each data terminal station. Each data terminal station detects a trip signal included in the received data and operates its own circuit breaker to interrupt the system.

In the above operation, all current data used in the current differential calculation of the relay calculation terminal 6 must be sampled at the same timing. Therefore, each terminal station adjusts its own sampling timing using the aforementioned sampling synchronization flag as a reference. The simplest method for controlling the sampling timing is to control the reception timing of the sampling synchronization flag SF in the received signal so that it is equal to the sampling timing of the local station. Each terminal station is equipped with a means for detecting a sampling synchronization flag and a means for measuring reception timing based on the sampling timing of the own station. control.

Another method is to accurately measure the delay time of each terminal station and transmission line when installing the current differential system, input it as a correction value to the terminal station, and take that value into account when controlling the sampling timing. Some also perform timing correction. This method has the advantage of reducing sampling synchronization errors due to transmission delays between terminal stations.

(Problem to be Solved by the Invention) In the synchronization method described above, the former does not require adjustment, but if the delay time between the transmission paths between each terminal station and within each terminal station is large, A large error occurred in the sampling timing, and there was a risk that the relay characteristics would deteriorate due to an increase in the differential current.

Furthermore, in the latter method, errors due to transmission delay time do not occur, but (1) the transmission path cannot be switched.

There were problems with installation and operation, such as (2) it took time to make adjustments during installation, and (3) when adding terminal stations, it was necessary to reset the timing of other terminal stations.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a sampling synchronization method that has a simple configuration and can accurately match sampling timings at each terminal station without adjustment.

[Structure of the Invention] (Means for Solving the Problems) Generally, a current differential relay system is often configured in a dual system form in order to improve reliability.

A duplex system connects each terminal station with two transmission lines,
Even if a failure occurs in one transmission line, the other transmission line can be used to transmit data without any problem and continue the protection operation. In the present invention, the transmission directions of these two transmission lines are opposite to each other, and sampling synchronization control is performed using the difference in arrival time of the transmitted signals. Fig. 2 shows an example of the configuration of the present invention. . In FIG. 2, each data terminal station is connected by a double loop-shaped transmission line. The two loose transmission paths transmit data in opposite directions from the data terminal station 2 (hereinafter referred to as the master station) as a starting point. Each terminal station other than the data terminal station 2 (hereinafter referred to as slave station) has two sets of transmitting/receiving means, and measures the reception timing of each received transmission signal. Each terminal station has a built-in sampling signal oscillator whose timing can be controlled, and the sampling time is controlled to a timing corresponding to the above-mentioned reception time.

(Function) The principle of the present invention is shown in FIG. FIG. 1 shows the state of transmission when a signal transmitted from the master station 2 goes around each data terminal station via transmission lines 12, 13, 14, and 15 and returns. In FIG. 1, the solid line indicates the delay of a signal transmitted clockwise through the data terminal station, and the dotted line indicates the delay of a signal transmitted counterclockwise. For the sake of explanation, in Fig. 1, the master station 2 is placed in two places, upper and lower.
1. A clockwise transmission signal is expressed as going from top to bottom, and a counterclockwise transmission signal is expressed as going from bottom to top.

In FIG. 1, two signals are sent out from the master station 2 to their respective transmission lines at the same time TS, and return to the master station 2 after passing through all the terminal stations. Since it can be assumed that the transmission delay time required for transmission in the same section is equal regardless of the transmission direction, the above two lines are symmetrical about the center line PQ.

Therefore, if the reception timings of the clockwise and counterclockwise transmission signals at each terminal station are TR and TL, respectively, the intermediate time (TR+TL)/2 between the reception times TR and TL always coincides at every terminal station. In other words, each terminal station receives the reception timing TR.

By measuring T[ and controlling the sampling timing using the intermediate time as a reference, it is possible to accurately control the sampling synchronization of all data terminal stations without adjustment.

(Example) Examples will be described below with reference to the drawings.

FIG. 2 is a configuration diagram of an embodiment for explaining the Zangling time synchronization method according to the present invention. In Figure 2,
Those with the same numbers as those in the conventional example have the same functions as those in the conventional example, and the explanation thereof will be omitted. 22, 23, 24.
Reference numeral 25 indicates a transmission line connecting data terminals in a counterclockwise direction.

Next, FIG. 3 shows an example of the internal configuration of each slave station.

In FIG. 3, 101 inputs the current data of the grid,
System electrical quantity input means for encoding for transmission, 102 and 202 receive data from the transmission path, receiving means for receiving and receiving data destined for the own station and simultaneously outputting a received signal to the transmitting means, 103 , 203 receives the output of the system electricity quantity input means 101 and the outputs of the receiving means 102, 202 as inputs, and transmits the current data collected at its own station by adding it to the received signal. 104, 204 receives the received data 105 is a flag detection means for detecting the sampling synchronization flag of the sampling synchronization flag detection means 10.
Using the output of 4,204 as input, the reception time difference TRL-TR
- flag arrival time difference measuring means for measuring TL; 106 is a sampling time measuring means for measuring the output timing of the sampling synchronization oscillator 107 of the local station based on the output signal of the sampling synchronization flag detection means 105; 107;
takes the outputs of the measuring means 105 and 106 as input, calculates the reference time of the sampling timing from both values,
A sampling timing control means controls the sampling timing of the own station according to the calculation result, and 108 indicates a sampling oscillator that is controlled by the sampling timing control means 107 and generates the sampling timing of the own station.

Next, FIG. 4 shows an example of single-layer configuration of the master station. In the case of a master station, the transmitting means 103, 203 is the system electricity input means 101 of its own station.
The output signal is used as a data input for transmission, and the timing signal output from the sampling oscillator 108 is used as a transmission timing control input for transmission.

The transmission signals received by the receiving means 102 and 202 are
-10~ Relay performance is sent to $ terminal station 6 and is not retransmitted.

Further, the flag detection means 104 and 204 are configured to receive the output of the transmitting means 203 and the input of the receiving means 202 for the transmission path in the same direction, and measure the time required for the sampling synchronization flag to make one round of the transmission system. In FIG. 4, the inputs of the flag detection means 104 and 204 are transmitted and received signals on a counterclockwise transmission path, but there is no problem in using the transmission and reception signals on a clockwise transmission path as well.

The present invention will be described in detail below based on the detailed timing diagram shown in FIG. FIG. 5 is a more detailed representation of FIG. 1, which shows the state of data transmission between each terminal station based on time. In FIG. 5, solid lines and dotted lines indicate the arrival timing of a specific portion of a signal transmitted on a transmission line, for example, a sampling synchronization flag, at each data terminal station, as in FIG. 1.

The solid line indicates the clockwise data transmission of the two loop-shaped transmission paths, and the dotted line indicates the counterclockwise transmission. Mana t 12. t13. t14. t15
are between data terminal stations 2-3, 3-4, 4-5, respectively.
5-1 shows the transmission delay time between 5 and 1.

The sampling oscillator 108 of the master station 2 of the data terminal station is 1
Transmission means 103.20 once per sampling at one time TS
3, and sends a signal containing the own station current data IA and sampling synchronization flag SF to transmission lines 12 and 2.
Send to 2. The clockwise signal transmitted from the master station 2 arrives at the slave station 3 in FIG. 2 after a transmission delay time t12, and after adding the current data IB of the terminal 3,
Sent on 3rd.

The transmitted signal passes through the transmission line 13 and reaches the slave station 4,
Thereafter, similar processing is performed, and the process finally returns to the master station 2. At this time, the reception timing TRR of the signal in the slave station is 1-1 to 1-4 based on the transmission timing TS of the master station 2.
Expressed as:

Slave station 3: T3R=t12
(1-1) Slave station 4: T4R=t12+t
13' (1-2) Slave station 5: T5
R= t 12+ t 13+ t 14 (
1-3) Master station 2: T2R=t12+t13+t14
+t15 (1-4) Next, consider the signal transmitted from the master station 2 in the counterclockwise direction. In this case, since the upstream/downstream transmission delay times of the same transmission path are considered to be equal, the arrival timing of each terminal station is expressed by two equations.

Slave station 5: T5L=t15
(2-1) Slave station 4: T4L=t15+t
14 (2-2) Slave station 3: T3L=
t 15+ t 14+ t 13 (2-
3) Master station 2: T2L=t15+t14+
t 13 + t 12 (2-4) - As an example, when comparing the timing in the case of slave station 4, the timing of the timing TSH intermediate between the clockwise data reception timing T4R and the counterclockwise data reception timing T4L is as follows. It is expressed by equation (3).

TSH= (T4L-T4R) /2+T4R=(t1
4+t15-t12-t13)/2+t12 +t13
=(t12+t13 +t14 +t15)/2
(3) The above equation (3) holds exactly the same for slave stations 3 and 5. Also, in the case of master station 2, the transmission timing and reception timing of the own station are determined as TSH.
3 = By using the time in the middle of T2L (=T2R)<T2L/2), the same equation as equation (3) can be obtained.

As explained above, in each terminal station, the timing T between the clockwise data reception timing TNR and the counterclockwise data reception timing TNL (N=3.4.5>
SH always has the same timing.

Therefore, by controlling the sampling time of each terminal station based on the above timing, it is possible for all terminal stations to perform sampling at the same timing.

Regarding control of sampling synchronization at actual terminal stations,
This will be explained based on an example of the slave station 4.

In FIG. 3 showing an example of the configuration of a slave station, a reception signal received by slave station 4 is input to detection means 104, 204. When the detection means 104 and 204 detect a pattern of the sampling synchronization flag SF in the received signal, they output a sampling synchronization flag detection signal to the flag arrival time difference measurement means 105 and the Sands link time measurement means 106. The flag arrival time difference measuring means 105 starts counting with the inputted first sampling synchronization flag detection signal, and then ends counting with the other inputted sampling synchronization flag detection signal. Therefore, as the output of the flag arrival time difference measuring means 105, the difference between the arrival times of the sampling synchronization flags by the two opposite transmission paths T4RL -T4
RT41- is obtained.

Similarly to the flag arrival time measuring means 105, the sampling time measuring means 106 starts counting at the first sampling synchronization flag detection signal, and stops counting at the sampling reference timing T4ST of its own station. As a result, the difference T4R3 between the reception timing of the sampling synchronization flag and the sampling reference time of the own station is obtained.

The difference T4RL between the sampling synchronization arrival times and the difference T4R3 between the sampling timing of the own station and the sampling synchronization timing are input to the sampling synchronization control means 107. The sunblink synchronization control means 107 calculates the difference between the arrival time difference T4RL 172 and the arrival time T4R3 as the sampling synchronization error ΔT, and controls the sunblink synchronization oscillator 108 of its own station so that the difference between the two becomes zero.

As an example of control, sampling synchronization error ΔT-T4RL
, /2'-T4R8<O, it is determined that the sampling timing of the own station is delayed, and the oscillation frequency of the sampling oscillator 108 is slightly increased, and ΔT=
If 74RL, /2-T4R8>O, the oscillation frequency is lowered. As a result, the sampling timing TST of the local station is always held at the center TSH of the two sampling synchronization flag reception timings, and the two timings coincide with each other with high accuracy. The above explanation is for terminal 4.
Alternatively, by performing exactly the same control on the other slave stations 3 and 5, the sampling timings can be made to match.

In the case of the master station 2, the flag arrival time difference measuring means 10
5 and the sampling time measuring means 106 use the transmission timing TS of the own station as a count start input when measuring the arrival time difference T2RL and the arrival time T2R8, thereby performing the same control as other slave stations 3, 4.5. is possible.

By the above procedure, the sampling timings can be made to match between the master station 2 and the slave stations 3 and 4, and the entire system can be sampled simultaneously.

As described above, according to the control method of the embodiment of the present invention described in FIG. 1, the sampling timing of the entire system can be automatically kept constant regardless of the transmission delay time between each terminal station. It is also possible to significantly reduce the adjustment work required for sampling synchronization control when installing a system or changing a transmission system.

Examples other than the above may be listed below.

■ In the embodiment of the present invention explained in FIG. 1, the explanation was given assuming that the time required for retransmission of the received signal reaching each data terminal station is O, but the present invention is not limited to this. do not have. The present invention can be easily applied even when it takes a processing time td from receiving a signal from the previous terminal station to adding data of the own station and sending the signal.

FIG. 6 shows a timing diagram illustrating transmission delay control when a delay td occurs when passing through a terminal station.

In Fig. 6, the sampling synchronization flag reception timing in the clockwise direction transmission path is expressed by formulas 4-1 to 4-4.
For example, in the case of slave station 4, the sampling synchronization flag transmission timing in the signal transmitted in the opposite direction is expressed as shown in 4RR. The middle of the transmission timing T4LT of the transmission path can be expressed by equation (6). Formula 4-1.4-: '3 and Formula 5-1
．． 5-3, it can be seen that the value of equation (6) is constant for the other slave stations 3 and 5 as well. Regarding the master station 2, the time required for one round of the transmission path is T 2
RI (1/2 of Equation (6)) At all data terminals, Equation (6
) are equal, if a delay td occurs when passing through a terminal station, an embodiment of the present invention uses the timing TSH intermediate between the reception timing of one transmission path and the transmission timing of the other transmission path as a reference timing. It is possible to perform sampling synchronization control similar to that described above.

Sampling synchronization flag reception timing via clockwise transmission path Slave station 3: T38R-112 (4-1) Slave station 4:
T4RR=t12→td+t13 (4-
2) Slave station 5: T5RR=t12+td+t1
3+td+t14 (4-3) Master station 2
: T2RR=t12+td+t13+td+t11
td+t15=112+t13+t14+t15+3t
d (4-4) Sampling synchronization flag transmission timing on counterclockwise transmission path Slave station 5: T5LT = t15÷td
(5-1) Slave station 4: T4LT = t15
+td 14+td (5-2)
Slave station 3: T3LT = t15 + td + t14
+td+t13÷td (5-3)TSH= (T
4LT -'14RR) /2 +T4RR=(t14
÷t15-t12-t13÷td), /2+t12
+td+t13= (t12+t13+t14+t1
5÷3td)/2 (6) ■ In the embodiment of the present invention explained in FIG. 1, the explanation was made on the assumption that the time required for one round of the loose transmission line was less than the time for one sampling. However, the present invention is not limited thereto. If the time required for one round exceeds the sampling interval, include the sampling synchronization flag in the transmission signal so that the interval at which each terminal station receives the sampling synchronization flag is longer than the time required for one round! It's good to spread 9Fi.

■ In the embodiment of the present invention described in FIG. 1, the clockwise/counterclockwise data transmitted from the master station were explained as being transmitted at the same time, but the present invention is not limited to this. It's not something you can do. The present invention is applicable even when the time at which data is transmitted from the master station to the clockwise transmission path and the time at which it is transmitted from the master station to the counterclockwise transmission path are different.

FIG. 7 shows a timing chart when there is a time difference TDT between the transmission of two signals. Even if there is a difference in transmission timing, it is possible to match the zangling synchronization of the entire system by setting the middle of the reception timing of the sampling synchronization flag as the sampling reference point, as in the case explained in the embodiment of FIG. I'll come.

■ In the embodiment of the present invention described in FIG. 1, the sampling timing of each data terminal station was explained as matching with the center of the reception timing of the two sampling synchronization flags, but the present invention is limited to this. It is not something that will be done. By using the central time as the reference point and controlling the time difference between the reference point and the sampling timing to be the same for all terminal stations, the sampling timing of each terminal station can be selected at any timing relative to the transmission signal. Ru.

■ In the embodiment of the present invention explained in FIG. is not limited to this. The present invention is applicable even when a two-loop transmission system is completely divided in terms of hardware. In that case, a transmission means for exchanging the reception timing of the sampling synchronization flag and the sampling timing signal may be provided between the two clockwise/counterclockwise transmission terminals provided at each terminal. .

■ In the embodiment of the present invention illustrated in FIG. 1, the sampling synchronization control is always performed while receiving two transmission systems, but the present invention is not limited to this. There isn't. Generally, the transmission delay time of a transmission line does not change significantly once it is installed, so the synchronization control data TRL calculated using equation (3) will always be a constant value. Therefore, when both transmission systems are normal, 2
Measure and store the reception time difference TRL of the two transmission lines,
When one transmission system becomes defective, sampling synchronization control is performed using the reception timing TNR or TNL (N is the number of the data terminal station) of the normal transmission system and the synchronization control data TRL during normal operation. It is possible.

[Effect of the Invention 1] As explained above, according to the present invention, the sampling timings of all terminal stations can be accurately matched regardless of the transmission delay time between the terminal stations, which solves the problem in current differential relay systems. This can eliminate deterioration in relay accuracy due to sunblink time differences.

Sampling synchronization is automatically performed according to the transmission path conditions. 1. Compared to the conventional method of correcting transmission delay time by measuring actual equipment, it is possible to significantly reduce the labor required for adjustment and confirmation during system installation and transmission system rearrangement.

[Brief explanation of the drawing]

FIG. 1 is a timing diagram showing the principle of the present invention, FIG. 2 is a schematic configuration diagram of the present invention, FIG. 3 is a diagram showing an example of the internal configuration of a slave station of the device of the present invention, and FIG. 4 is a diagram of the device of the present invention. A diagram showing an example of the internal configuration of the master station, FIG. 5 is a detailed timing diagram showing the principle of the present invention, FIG. 6 is a timing diagram showing the operation of a modified example of the present invention, and FIG. 7 is a further modified example. Timing diagram representing 8th
9 is a diagram showing the configuration of a conventional current differential relay device, and FIG. 9 is a diagram showing an example of a transmission format of transmission data of the current differential relay device. 1... Power transmission line, 2.3, 4.5... Data terminal station, 6... Relay calculation terminal station, 12, 13.14.15... Transmission line (clockwise), 2
2.23, 24.25...Transmission line (counterclockwise), 1
01... System electricity amount input means, 102.202... Receiving means, 103,203...
- Transmission means, 104.204...Flag detection means, 1
05...Flag arrival time difference measuring means, 106...Sampling time measuring means. 107...Sampling timing control means, 108
...Sampling oscillator. Agent: Patent Attorney Nori Chika Ken, Masaaki Daishimaru Ken Relay Calculation” dies

Claims (1)

[Claims] In a transmission system in which multiple terminal stations are loosely connected through multiple transmission paths with opposite transmission directions, a master station among the multiple terminal stations connects multiple transmission paths with opposite transmission directions to each other. A timing reference signal is transmitted at regular intervals, and the slave stations other than the master station use as a reference the intermediate time of the two timing reference signals received from transmission paths whose transmission directions are opposite to each other. A sampling time synchronization method characterized by controlling the sampling timing of its own station by