JP2011015543A - Digital protection relay system, and sampling synchronization method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in a conventional digital protection relay system using a GPS signal, in which the abnormal conditions of a GPS receiving signal cannot be handled when a delay time differs as a transmission path differs in a round trip during communication with an adjoining protection relay device.SOLUTION: A difference in delay time from a sampling signal in the round trip to data reception is calculated and stored. At the abnormal conditions of the GPS signal, the sampling signals of adjoining protection relay devices are synchronized, based on the difference between each delay time acquired anew and the stored delay time.

Description

  The present invention relates to a digital protection relay system for electric power that takes sampling synchronization by using GPS (Global Positioning System).

In a conventional protective relay system using GPS signals, the timing difference between the reference signal from the GPS receiver and the sampling signal of the protective relay device is measured, and the frequency of the sampling signal is corrected based on the timing difference. is doing. By correcting the frequency of the sampling signal of each protection relay device, the sampling signals of all the protection relay devices can be synchronized.
When the signal from the GPS receiver is interrupted, a technique for synchronizing the sampling signal from the data communication delay time between the adjacent protective relay device measured in advance and the current data reception timing is disclosed. Yes. (For example, see Patent Document 1)

JP 2002-186166 A

In the conventional digital protection relay system using the GPS signal, the sampling signal of each relay device is corrected according to the reference signal obtained from the GPS receiver.
In addition, when the radio wave from the GPS satellite or the signal from the GPS receiver is interrupted, the sampling signal is synchronized with the communication delay time between the adjacent protective relay device and the current data reception timing, which are measured in advance. Have taken. In the prior art, a method based on the premise that the delay time in communication with the adjacent protective relay device is equivalent to the return trip is shown. Therefore, there is a problem that it is not possible to cope with cases where the communication paths of the return journeys are different and the delay times are different.

  The present invention has been made to solve the above-described problem, and while ensuring high-accuracy synchronization by GPS signals, the transmission delay time with an adjacent protective relay device is different in return trips when GPS signals are abnormal. Even at times, it aims to synchronize the sampling time.

  The protection relay system according to the present invention optimizes the timing of the sampling signal by using the signal from the GPS receiver, the time Tms from the sampling signal to the data reception from the adjacent protection relay device, and the adjacent protection The delay time difference α is calculated and stored from the time Tsm from the sampling signal of the relay device to the data reception, and when the GPS signal is abnormal, it is adjacent from the newly obtained Tms, Tsm and the stored α value. Correction means for synchronizing with the sampling signal of the protective relay device is provided.

  In the present invention, when a signal from the GPS receiver becomes abnormal, the sampling signal can be corrected by a simple method without a large change in the calculation method. Even when there is a difference in the data communication delay time between sending and receiving data, the sampling signal can be corrected accurately.

It is a block diagram which shows the structure of Embodiment 1 of this invention. It is a figure which shows the sampling synchronous process 1 of Embodiment 1 of this invention. It is a figure which shows the flowchart 1 of Embodiment 1 of this invention. It is a figure which shows the flowchart 2 of Embodiment 1 of this invention. It is a figure which shows the flowchart 3 of Embodiment 1 of this invention. It is a figure which shows the flowchart 4 of Embodiment 1 of this invention. It is a block diagram which shows the structure of Embodiment 2 of this invention. It is a figure which shows the flowchart 5 of Embodiment 2 of this invention. It is a figure which shows the flowchart 6 of Embodiment 2 of this invention. It is a figure which shows the flowchart 7 of Embodiment 2 of this invention. It is a block diagram which shows the structure of Embodiment 3 of this invention. It is a figure which shows the sampling synchronous process 2 of Embodiment 4 of this invention. It is a figure which shows the sampling synchronous process 3 of Embodiment 4 of this invention. It is a figure which shows the flowchart 8 of Embodiment 4 of this invention. It is a figure which shows the flowchart 9 of Embodiment 4 of this invention. It is a figure which shows the flowchart 10 of Embodiment 4 of this invention. It is a figure which shows the flowchart 11 of Embodiment 4 of this invention.

Embodiment 1 FIG.
For example, the protective relay system measures the current vector of a transmission line several kilometers to a few tens of kilometers away by the protective relay device provided at both ends of the transmission line, compares the current vectors at both ends, and the difference is scheduled It is used to determine a failure when the value is exceeded and to disconnect the failure section from the power system. In order to compare current vectors between remote locations, a reference sampling signal is important, and in recent years, a reference signal generated from a GPS signal has been used.
The digital protection relay device uses a technique of digitizing an analog amount at every sampling time by a PCM (Pulse Code Modulation) method. The current vector at the other end transmitted as a digital signal is compared with the current vector at the same time at the other end. If the vector difference exceeds a predetermined amount, a failure is determined and the failure section is cut off.

FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention.
The digital protection relay system 1 is configured by connecting an adjacent first digital protection relay device 101 and a second digital protection relay device 201. Here, for the sake of convenience, the first digital protection relay device 101 is called a slave station and the second digital protection relay device 201 is called a master station, but this may be reversed.
First, the slave station when the GPS signal is normal will be described. When the GPS signal is normal, the GPS signal 138 is correctly transmitted from the GPS receiver to the slave station 101. Here, the GPS signal 138 indicates a signal for synchronization periodically transmitted from the GPS receiver to the slave station 101.
The GPS signal abnormal time includes not only the case where the radio wave from the GPS satellite does not properly reach the ground, but also the failure of the GPS receiver, the abnormal time of the signal line transmitting the signal from the GPS receiver, and the like.
The slave station 101 converts A / D conversion means 102 for converting analog data 131 of its own electrical quantity into digital data, and first electrical quantity data which is digital data relating to its own electrical quantity from the A / D conversion means 102. Data processing means 103 that receives the received data, processes the data into transmission data, and passes the data to the data communication means 105. The data communication means 105 transmits the first electric quantity data to the main station through the first data communication path, and the second electric quantity data related to the electric quantity at the other end from the main station through the second data communication path. The data calculation means 103 receives the first electric quantity data and the second electric quantity data, and if the absolute value of the difference is larger than a predetermined value, the data calculation means 103 trips through the output means 104. The signal 132 is output.
The sampling signal output means A106 has a clock inside, but receives the GPS signal 138, corrects the period of the signal by the internal clock to the correct period by the correction value Kf, and converts the first sampling signal 133 to A / The data is supplied to the D converter 102, the data calculation means 103, and the data communication means 105, and analog data A / D conversion and data transmission are performed in synchronization.
Similarly, the main station 201 includes A / D conversion means 202, data communication means 205, data calculation means 203, and sampling signal output means A206.
Similarly to the first sampling signal 133, the second sampling signal 233 output from the sampling signal output means A206 is synchronized with the GPS signal, so that analog data A / D conversion and data of the slave station 101 and the master station 201 are obtained. Transmission is performed synchronously.

In the slave station 101, the delay time difference calculating means 107 receives data communication delay time information with the adjacent master station from the data communication means 105.
The delay time difference calculation means 107 outputs a second data communication delay time (Td1) from when the first sampling signal is output at the slave station until the second electric quantity data transmitted by the master station is received through the second data communication path. ) Data. Then, the data of the second data communication delay time (Td2) from when the second sampling signal is output at the master station to when the first electrical quantity data transmitted by the slave station is received through the first data communication path is obtained. Received via the data communication means 105. Further, a delay time difference (α) is calculated from the first and second data communication delay times (Td2, Td1), and the calculation result is stored in the storage means. The upstream first data communication path from the slave station to the master station may be different from the downstream second data communication path from the master station to the slave station. Since the second data communication delay time may be different, there is a delay time difference (α).

When the GPS signal 138 becomes abnormal, the first sampling signal 133 is output by the first sampling signal output means A106 while maintaining the correction value Kf when the GPS signal is normal with reference to the internal clock. To do. At this time, there is a possibility that the timing of the first sampling signal 133 and the second sampling signal 233 may be shifted between the slave station 101 and the master station 201 as time elapses.
After the GPS signal 138 becomes abnormal, the timing difference calculation means 110 receives from the data communication means 105 the first time from the output of the first sampling signal at the slave station to the reception of the second electrical quantity data transmitted by the master station. 4 data communication delay time (Tms) is received. Then, the data communication means 205 of the main station transmits the data of the third data communication delay time (Tsm) from the output of the second sampling signal at the main station to the reception of the first electric quantity data transmitted by the slave station. The timing difference calculation means 110 receives the contents obtained through the data communication means 105.
The delay time difference α calculated when the GPS signal is normal and stored in the storage means 108 is received from the delay time difference calculation means 107, and the timing difference calculation means 110 receives the timing difference of sampling signals between the slave station 101 and the master station 201 from these data ( ΔT) is calculated. The first correction unit 111 transmits the first correction signal 137 to the sampling signal output unit A according to the calculated timing difference (ΔT), and the first sampling signal 133 output by the sampling signal output unit A106 is Synchronize with the second sampling signal 233 of the main station 201.
Even when the GPS signals 138 and 238 become abnormal, the first sampling signal 133 can be synchronized with the second sampling signal 233 by the same processing as described above.

FIG. 2 is a diagram showing sampling synchronization processing 1 according to the first embodiment of the present invention.
Hereinafter, the calculation of the data communication delay time and the delay time difference α and the calculation of the timing difference ΔT will be described.
FIG. 2A shows the timing of data transmission / reception when the signal of the GPS receiver is normal and the output timings of the sampling signals of the master station 201 and the slave station 101 that are adjacent protection relay devices match. ing.
An upward arrow indicates a sampling signal in each station, and the amount of electricity sampled in each station is transmitted in synchronization with the sampling signal. In addition to data on the sampling timing of each station, data such as data communication delay time, data serial number from a predetermined point, and absolute time are required for data transmitted and received between the master station and slave stations. Included in frequency.
When the first data communication path from the slave station to the master station is different from the second data communication path from the master station to the slave station, the data communication delay time from the start of transmission to the completion of reception may be different in uplink and downlink. .
The first data communication delay time Td2 from the slave station to the master station (upstream) and the second data communication delay time Td1 from the master station to the slave station (downlink) are the same in the sampling time of the master station and the slave station. If the time from the sampling signal to the time of data reception is measured on the receiving side, it can be measured correctly. Therefore, the difference α between the upstream and downstream data communication delay times can be obtained from Equation (1).

α = Td2−Td1 (1)

FIG. 2B shows the data transmission / reception timing when the GPS signal is abnormal and the sampling signals of the master station and the slave station have a timing difference of ΔT.
Since the reception time of transmission data from each station can be measured only on the reception side, the time from the sampling signal of the own station at the reception station to the completion of reception is the third data communication delay from the slave station to the master station (upstream). The time Tsm is measured as the fourth data communication delay time Tms from the master station to the slave station (downward). These data are values including the timing difference ΔT between the sampling signals of the master station and the slave station. Therefore, Tms and Tsm can be expressed by the following equations.

Tms = ΔT + Td1 (2)
Tsm = Td2-ΔT (3)

(1) From (2) (3)

ΔT = (Tms−Tsm + Td2−Td1) / 2

ΔT = (Tms−Tsm + α) / 2 (4)

Therefore, the delay time difference α is calculated from the first data communication delay time Td2 and the second data communication delay time Td1 when the GPS signal is normal, and this value is measured at each station after the GPS signal becomes abnormal. From the third data communication delay time Tsm and the fourth data communication delay time Tms, the timing difference ΔT between the sampling signals of the master station and the slave station can be obtained.
If the output of the sampling signal output means A106 of the slave station is shifted by this ΔT value, the sampling signal of the master station and slave station can be synchronized.
FIG. 2 shows an example in which each station alternately transmits data once every two sampling signals, but each station may transmit data every time a sampling signal is received.
Hereinafter, the procedure in the case where each station transmits data for each sampling signal will be described.

FIG. 3 is a diagram showing a flowchart 1 of the first embodiment of the present invention.
The digital protection relay system according to the first embodiment is configured by connecting the slave station 101 and the master station 201. The operation of the slave station 101 will be described.
The flowchart of FIG. 3 shows a case where the microcomputer supervises the function of each block of the slave station 101 of FIG. Here, equivalent processing can be performed even if a PLD (programmable logic device) is used instead of the microcomputer.
Step 500 in FIG. 3 indicates the start of an interrupt process in which an interrupt is generated upon receipt of a GPS signal 138 from a GPS receiver and the program is activated.
In step 501, a time interval Pgps between the time Tgps (n-1) at which the previous GPS signal was received and the time Tgps (n) at which the current GPS signal was received, and a predetermined sampling signal period Pclk set in the internal clock. In comparison, a correction value Kf for correcting the period of the internal clock is calculated by the following equation, and the process proceeds to step 510.

Kf = (Pclk / Pgps) −1 (5)

From step 510, a procedure is shown in which the period correction value Kf of the internal clock is divided into a fixed correction value Kfs and a variable correction value Kfv and stored in the memory. The calculation and storage of Kfs and Kfv is executed every time the predetermined period Tf elapses. For example, if Tf = 1 second, it is executed every second.
In step 510, it is determined whether or not a predetermined time Tf has elapsed since the previous update of Kfs. If not, the process proceeds to step 516.
If the predetermined time Tf has elapsed, Kfs is read from the memory in step 511, and a difference (Kf−Kfs) between Kfs calculated in step 501 and Kfs read from the memory is calculated in step 512, and the result is positive. If yes, go to Step 513, if zero, go to Step 515, if negative, go to Step 514. In step 513 and step 514, Kfs is updated by adding or subtracting Kfs to Kfs by a very small value of Klsb, for example, 1 ppm.
For example, the value of the correction value Kf is added to Kfs by 1 ppm every second, and the correction value Kf is expressed as the sum of the fixed correction value Kfs and the variable correction value Kfv as shown in the equation (6). be able to.

Kf = Kfs + Kfv (6)

If Kfs and Kfv are updated after a sufficient amount of time has passed, a reference signal generated from the GPS signal with a signal generated from the internal clock and a fixed correction value Kfs that corrects a portion that deviates at a constant rate It can be calculated and stored in a memory by dividing it into variable correction values Kfv for correcting a portion that changes every moment, such as fluctuations in ambient temperature, voltage, humidity, atmospheric pressure, etc., and fluctuations inherent in each digital relay device.
In step 515, Kfv is calculated from Kf−Kfs for the updated Kfs,
Kfs and Kfv are stored in the memory and the process proceeds to step 516.

In step 516, it is determined whether or not the absolute value of Kf is less than 0.1. If the absolute value of Kf is 0.1 or more, it is determined that the correction value Kf is excessive and unreliable, and the process proceeds to step 519 to end the interrupt process.
Here, the determination value 0.1 may be a different value such as 0.01, and is determined in view of a value that the actual machine can take.
If the absolute value of Kf is less than 0.1, it is determined that the correction value Kf is reliable, the GPS signal abnormality timer is cleared in step 517, the GPS normal counter is added in step 518, and the interrupt process is terminated in step 519.
In the steps of the flowcharts of FIGS. 3 to 5, the terms “GPS signal normal timer”, “GPS signal normal flag”, “GPS signal abnormal timer”, and “GPS signal abnormal flag” are used.
These are counters and flags used to determine whether the signal from the GPS receiver is normal or abnormal.

FIG. 4 is a flowchart 2 illustrating the operation of the slave station 101 according to the first embodiment of the present invention.
When the timing for outputting the sampling signal is set and the time measured with the internal clock has elapsed, a timer interrupt is generated and step 540 is activated.
This timer interrupt is set to generate a predetermined sampling timing signal by the internal clock. For example, if sampling is performed every 60 degrees at an electrical angle of 60 Hz, a timer interrupt is generated at 720 Hz (every 1.39 ms).
In this interrupt process, first, at step 541, the sampling signal 133 is output. In step 542, the correction value Kf calculated by comparing with the GPS signal is used for a predetermined sampling signal output period Pclk to set the next activation timer (1).
The value multiplied by + Kf) is set in the timer. This makes it possible to generate a sampling signal that is substantially synchronized with the signal from the GPS receiver next time.
In step 551, the A / D converted electric quantity data of the slave station is stored together with the serial number, and in step 552, the data is transmitted to the master station via the data communication means. Thereafter, in step 553, the slave data counter is added to prepare for the next data storage.
In step 561, a GPS signal abnormality timer is added. Since the timer addition in step 561 is performed at the sampling signal generation interval, the timer addition is performed at 720 Hz (every 1.39 ms) when sampling is performed every 30 degrees of 60 Hz electrical angle.
When the GPS signal can be normally received, the GPS signal abnormality timer is cleared in step 517 of FIG. 3 every time the GPS signal is received at the timing of 720 Hz, so the counter value hardly increases.
In step 562, it is determined whether or not the GPS signal abnormality timer is equal to or greater than Te2. For example, if Te2 = 720, it is determined that the signal from the GPS receiver is not normally received for 1 second or longer. If the added value of the GPS signal abnormality timer is equal to or greater than Te2, the process proceeds to step 565, the GPS signal abnormality flag is set, and the process proceeds to step 566.
When the value of the GPS signal abnormality timer is less than Te2, the process proceeds to step 563 and it is determined whether or not it is equal to or greater than Te1. For example, if Te1 = 72, it is determined whether it is 0.1 second or more and less than 1 second. If the GPS signal abnormality timer is in this area, the process proceeds to step 564 to clear the GPS signal normal counter and step. Proceed to 566.
If the value of the GPS signal abnormality timer is less than Te1, the process proceeds to step 566 as it is.
In step 566, it is determined whether or not the value of the GPS normal counter is equal to or greater than Cn. For example, if Cn = 720, it is determined that a normal GPS signal is received for one second or more. Then, in step 569, the GPS abnormality flag is cleared, and in step 569, the interrupt process is terminated.
In step 566, if the value of the GPS normal counter is less than Cn, the GPS signal normal flag is cleared in step 567 and interrupted in step 569 to indicate that the GPS signal is not reliable and not suitable for use. End the process.
The processing procedure described with reference to FIGS. 3 and 4 is the same for the operation of the main station 201.

5 and 6 are flowcharts 3 and 4 illustrating the operation of the slave station 101 according to the first embodiment of the present invention.
First, the flowchart 3 of FIG. 5 will be described. Interrupt processing when the slave station 101 receives the communication data 135 from the master station 201 is started in step 601.
In step 602, it is confirmed whether the GPS signal abnormality flag is set. If the GPS signal abnormality flag is not set, the process proceeds to step 612.

If the GPS signal abnormality flag is set in step 602, the process proceeds to step 603. In step 603, it is determined whether the absolute value of the correction value Kf is less than a predetermined value K1. If it is K1 or more, the absolute value of the correction value is large. Therefore, it is considered that the sampling signal of the master station and the slave station is likely to be shifted when the GPS signal is abnormal. move on.
If the absolute value of the correction value Kf is less than K1 in step 603, the process proceeds to step 604. In step 604, the time Tra is obtained by the function F1 of the absolute value of the correction value Kf, and in step 605, it is compared with the GPS signal abnormality timer to determine whether the timer value is smaller than Tra. The function F1 may be determined so that the time Tra decreases as the absolute value of the correction value Kf increases, and is approximately inversely proportional, but a discontinuous curve or straight line may be defined in the map.
Here, the predetermined value for comparing the timer value is set as Tra and is a function of the absolute value of the correction value Kf.
When the timer value is greater than or equal to Tra, it is considered that a sufficient time has passed since the GPS signal became abnormal, and there is a possibility that the sampling signals of the master station and the slave station have shifted. Therefore, Td1, Td2, The process proceeds to step 621 without updating α.
If the timer value is smaller than Tra in step 605, it is determined that the elapsed time since the GPS signal abnormality has occurred is short, and the process proceeds to step 606.
In step 606, the variable correction value Kfv is read from the memory among the correction values of the signal from the GPS receiver based on the signal from the internal clock, and whether the absolute value is less than the predetermined values K2 determined in step 607. Judge whether. If the absolute value of the variable correction value Kfv is equal to or greater than K2, it is considered that there is a high possibility that the sampling signal of the master station and the slave station will shift, so that the process proceeds to step 621 without updating Td1, Td2, α.
In step 607, when the absolute value of the variable correction value Kfv is less than K2, the process proceeds to step 608. In step 608, the time Trb is obtained by the function F2 of the absolute value of the variable correction value Kfv, and in step 609, it is compared with the GPS signal abnormality timer to determine whether the timer value is smaller than Trb. The function F2 may be determined so that the time Trb decreases as the absolute value of the variable correction value Kfv increases, and is approximately inversely proportional. However, a discontinuous curve or straight line may be defined on the map.
Here, the predetermined value for comparing the timer value is Trb and is a function of the absolute value of the variable correction value Kfv. However, if a fixed value is used, the need for map setting or the like is reduced, which can be realized simply.
When the timer value is equal to or greater than Trb, it is considered that a sufficient time has elapsed since the GPS signal became abnormal, and the sampling signals of the master station and the slave station are deviated, so updating Td1, Td2, α Go to step 621.
In step 610, it is confirmed whether or not the data communication path has been changed. Between the slave station and the master station, not only the data of the electric quantity sampled at a predetermined timing is exchanged, but also the data communication delay time and the data related to the data communication path being used are exchanged at the same time.
If it is determined from these data that the data communication path has been changed, the process proceeds to step 612. When the change of the data communication path is not informed, the process proceeds to step 611 to determine whether or not the data communication delay time has changed significantly. Specifically, the actually measured data communication delay time, Tsm and Tms are compared with Td2 and Td1 measured when the GPS signal is normal, and one of the absolute values of the difference is a predetermined value Tk determined in advance. If it is above, it will be judged that it changed greatly.
If the data communication delay time has not changed significantly, the process proceeds to step 621.
If the data communication delay time has changed significantly, it is determined that the uplink or downlink data transmission path has been changed, and the process proceeds to step 612.

Next, the flowchart 4 of FIG. 6 will be described.
Steps 611 and 612 in FIG. 5 follow steps 611 and 612 in FIG.
In step 612A and subsequent steps, Td1, Td2, and α are updated on the assumption that the sampling signals of the master station and the slave station are substantially synchronized.
In step 612A, the m-th main station electricity quantity data transmitted from the main station and the first data communication delay time Td2 are stored in the memory.
In the next step 613, the time from when the slave station outputs the first sampling signal until it receives data from the master station is calculated and stored in the memory as the second data communication delay time Td2.
In the next step 614, the delay time difference α is obtained from Td1 and Td2 by the equation (1) and stored in the memory. Thereafter, the process proceeds to step 630.

In step 621A, the received m-th main station electricity quantity data is stored in the memory. Since the third data communication delay time Tsm from the sampling signal measured on the master station side until the slave station data is received is transmitted from the master station, the received data Tsm is also stored in the memory.
Next, in step 622, a fourth data communication delay time Tms from the output of the first sampling signal in the slave station to the completion of reception of communication data from the mth master station is calculated and stored in the memory. To do.
Subsequently, in step 623, the timing difference ΔT between the sampling signal of the master station and the slave station is calculated by equation (4), stored in the storage means, and the process proceeds to step 624.
In step 624, the output timing of the sampling signal 133 is shifted using the timing difference ΔT. By the shift of ΔT, the sampling timing difference between the master station and the slave station is corrected, and both sampling timings can be synchronized.

Thereafter, in step 630, the latest and same electric quantity data of the same serial number m stored in the memory of the master station and the slave station are compared. If the absolute value of this difference is larger than a predetermined value K, the process proceeds to step 632 and the power system is shut off. In step 639, the interrupt process is terminated.
If the absolute value of the difference between the master station and the slave station in step 631 is less than the fixed value, the process proceeds to step 639 and the interrupt process is terminated.
As described above, regarding the first embodiment, after the signal from the GPS receiver becomes abnormal, determination is made using the correction value Kf and the variable correction value Kfv, or a function related to these values, and Td1, Td2, α The process of permitting the update of has been described. These processes can be applied not only to the first embodiment but also to the second and third embodiments described later in the same procedure.

  In the first embodiment of the present invention, when the signal from the GPS receiver becomes abnormal, the sampling signal can be corrected by a simple method without significant change in the calculation method, and adjacent protection can be performed. Even if there is a difference in the data communication delay time for sending and receiving data with the relay device, the sampling signal can be corrected accurately.

  In addition, even when the GPS signal is abnormal, when it can be estimated that the timing difference between the sampling signal of the master station and the slave station is small, the change in the uplink and downlink data communication delay times Td1 and Td2 and the change in the delay time difference α Correspondingly, these values stored in the memory can be updated. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

In addition, as shown in step 610 of FIG. 5, a change in the data communication path is detected from the data communication path information transmitted / received at the same time when the electrical quantity data is transmitted / received between the master station and the slave station. Even when the GPS signal is abnormal, if other conditions are met, these values stored in the memory corresponding to the changes in the uplink and downlink data communication delay times Td1 and Td2 and the change in the delay time difference α are stored. Can be updated. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.
Further, as shown in step 611 of FIG. 5, when the change of the data communication path is determined from the change amount of the data communication delay time, and the change amount exceeds a predetermined value, the uplink and downlink data communication delay time Td1 By updating these values stored in the memory in response to changes in Td2 and delay time difference α, it is possible to cope with changes in the data communication path, and the subsequent master station and slave stations. It is possible to accurately perform the correction when the timing difference of the sampling signal occurs.

  Further, as shown in step 608 of FIG. 5, it is estimated that the timing difference between the sampling signals of the master station and the slave station is small until a predetermined time elapses after the GPS signal becomes abnormal. These values stored in the memory can be updated in response to changes in the times Td1 and Td2 and changes in the delay time difference α. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

  As shown in step 603 of FIG. 5, the absolute value of the correction value Kf obtained by correcting the period Pclk of the signal generated by the internal clock of the digital protection relay device with the period Pgps obtained from the GPS signal is based on a predetermined value K1. If it is small, it can be estimated that the timing difference between the sampling signals of the master station and the slave station is small, so these stored in the memory corresponding to the changes in the uplink and downlink data communication delay times Td1 and Td2 and the change in the delay time difference α The value can be updated. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

  As shown in steps 604 and 605 in FIG. 5, the function F1 (|) of the absolute value of the correction value Kf obtained by correcting the period Pclk of the signal generated by the internal clock of the digital protection relay device with the period Pgps obtained from the GPS signal. The determination value Tra is determined by Kf |), and it can be estimated that the timing difference between the sampling signals of the master station and the slave station is small until the elapsed time after the GPS signal becomes abnormal exceeds Tra. These values stored in the memory can be updated in response to changes in the first data communication delay time Td2 and the second data communication delay time Td1 and changes in the delay time difference α. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

  As shown in step 607 of FIG. 5, the absolute value of the variable correction value Kfv of the correction value Kf calculated by comparing the signal generated from the internal clock of the digital protection relay device with the signal obtained from the GPS signal is determined in advance. If it is smaller than the predetermined value K2, it can be estimated that the timing difference between the sampling signals of the master station and the slave station is small. These values stored in can be updated. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

  As shown in steps 608 and 609 in FIG. 5, the absolute value of the variable correction value Kfv of the correction value Kf calculated by comparing the signal generated from the internal clock of the digital protection relay device and the signal obtained from the GPS signal is obtained. Since the determination value Trb is determined by the function F2 (| Kf |) and the elapsed time after the GPS signal becomes abnormal becomes Trb or more, it can be estimated that the timing difference between the sampling signals of the master station and the slave station is small. These values stored in the memory can be updated in response to changes in the uplink and downlink data communication delay times Td1 and Td2 and changes in the delay time difference α. As a result, it is possible to cope with a change in the data communication path, and it is possible to accurately perform correction when a timing difference between the sampling signals of the master station and the slave station thereafter occurs.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing the configuration of the second embodiment of the present invention.
The digital protection relay system 2 is configured by connecting the adjacent first digital protection relay device 181 and the second digital protection relay device 281.
Here, as in the first embodiment, the first digital protective relay device 181 is called a slave station, and the second protective relay device 281 is called a master station, but the reverse may be possible.
Regarding the function blocks inside the slave station 181 and the master station 281, the same numbers are assigned to the same function blocks as those in the first embodiment.
In the following, differences from the first embodiment will be described while comparing with the first embodiment.
In the first embodiment, the sampling signal output means A106 has a clock inside, receives the GPS signal 138, corrects it, and outputs a sampling signal. As shown in the flowchart of FIG. 4, the sampling signal is generated by a timer interrupt using an internal clock.
In the second embodiment, as shown in FIG. 7, the aforementioned internal clock is present in the backup reference signal generation means 114. The output of the backup reference signal generation means 114 generated with reference to the internal clock is corrected by the second correction means 115 that receives the GPS signal 138 via the reference signal generation means 113 and corrects it. As in the first embodiment, correction is performed using the correction value Kf.
The output of the backup reference signal generation means 114 is selected by the switch 112 only when the GPS signal is abnormal and supplied to the sampling signal output means B116. However, when the GPS signal is normal, the output of the backup reference signal generation means 114 based on the internal clock is not selected by the switch 112 and does not affect the sampling signal, which is different from the first embodiment.

FIG. 8 shows a flowchart 5 according to the second embodiment of the present invention.
In the following flowchart, an example in which each function of the block diagram shown in FIG. 7 is realized by software is described.
The digital protection relay system according to the second embodiment is configured by connecting the slave station 181 and the master station 281. The operation of the slave station 181 will be mainly described.
FIG. 8 is different from FIG. 3 in the flowchart 1 according to the first embodiment only in that a step 502 is added after the step 501 in FIG.
In step 500 of FIG. 8, an interrupt process is started in which an interrupt is generated in response to the GPS signal 138 from the GPS receiver and the program is started.
After calculating the internal clock cycle correction value Kf at step 501, the sampling signal 133 is output at step 502. The output of the sampling signal is a trigger, and the sampling signal interrupt shown in FIG. 10 is requested as an interrupt process by an external signal.
Since step 510 after step 502 is the same as FIG. 3 described in the first embodiment, the description thereof is omitted.

FIG. 9 shows a flowchart 6 according to the second embodiment of the present invention.
The internal clock incorporated in the backup reference signal generation means 114 generates a timer interrupt every time the set timer value elapses, and step 741 is activated. This timer interrupt is for transmitting a sampling signal instead of a GPS signal when the GPS signal is abnormal. For example, in the case of transmitting a sampling signal every 30 degrees of 60 Hz electrical angle, 720 Hz (1.39 ms). Generate a timer interrupt every time.
In this interrupt process, first, in order to set the next activation timer in step 742, a predetermined sampling signal output period Pclk is multiplied by (1 + Kf) using a correction value Kf calculated by comparing with the GPS signal. The set value is set in the timer. As a result, a timer interrupt can be generated next time at a timing substantially synchronized with the signal from the GPS receiver.
Next, in step 743, if the difference between the current time and the previous sampling signal output time exceeds 1.5 times the sampling 9th cycle, it is determined that the GPS signal is interrupted. In step 744, the sampling signal is Output, and interrupt is terminated in step 749.
If it is determined in step 743 that the current time has not passed 1.5 · Pclk from the sampling signal output time, step 744 is skipped and the interrupt is terminated.
When the GPS signal is actually interrupted, the next sampling cycle is in a standby state after the disruption, and the sampling signal is lost once. At the next timer interrupt, since 1.5 · Pclk time has passed since the previous sampling signal was sent, sampling signal output by the internal clock is started.

FIG. 10 is a diagram showing a flowchart 7 according to the second embodiment of the present invention.
FIG. 10 shows a program to be executed when an external signal interrupt is generated using the output of the sampling signal as a trigger when the sampling signal is output in step 502 of FIG. 8 or step 744 of FIG.
The external signal interrupt is activated by the sampling signal output, and the processing starts from step 701. In the next step 550, the sampling signal output time is stored in preparation for the disruption of the sampling signal due to the GPS signal abnormality, and thereafter, the processing executed for each sampling signal is described from step 551 onward. Since the processing is the same as that after step 551, the description thereof is omitted.

The processing procedures described in FIGS. 8, 9, and 10 are the same for the operation of the main station 281.
In addition, the interrupt process when receiving transmission data from the main station shown in the flowcharts 3 and 4 in FIGS. 5 and 6 is used in the second embodiment as it is in the first embodiment.

In the second embodiment of the present invention, since the digital protection relay system is mainly operated with GPS signals, it is possible to construct a system that can be synchronized very accurately. In addition, since it is operated based on the GPS signal from the beginning of installation and activation, it is possible to eliminate the necessity of adjusting the deviation of the sampling signal between the digital protection relay devices due to the operation by the internal clock, and installation and activation are possible. It becomes very simple.

Embodiment 3 FIG.
FIG. 11 is a block diagram showing the configuration of the third embodiment of the present invention.
The digital protection relay system 3 is configured by connecting the adjacent first digital protection relay device 182 and the second digital protection relay device 282.
Here, as in the first embodiment, the first digital protective relay device 182 is referred to as a slave station and the second protective relay device 282 is referred to as a master station.
Regarding the function blocks inside the slave station 182 and the master station 282, the same numbers are assigned to the same function blocks as those in the first embodiment.
In the following, differences from the first embodiment will be described while comparing with the first embodiment.
In the first embodiment, the sampling signal output means A106 has a clock inside, receives the GPS signal 138, corrects it, and outputs a sampling signal. As shown in the flowchart of FIG. 4, the sampling signal is generated by a timer interrupt using an internal clock.
Embodiment 1 FIG. Then, when the GPS signal becomes abnormal, the timing difference calculation means 110 outputs the timing difference ΔT between the sampling signals of the master station and the slave station to the first correction means 111, and the first correction means 111 performs the sampling. The output timing of the signal 133 is shifted and synchronized. On the other hand, in the third embodiment, the timing difference calculation means 110 transmits the data of the timing difference ΔT to the main station via the data communication means 105, and sends the data to the third correction means 219 of the main station. The difference is that the sampling signal of the master station and the slave station are synchronized by shifting the output timing of the sampling output signal.

In the third embodiment of the present invention, the calculation of the timing difference ΔT and the shift of the sampling signal due to the timing difference ΔT are shared by the slave station and the master station, and the magnitude of the load on the master station and the slave station is leveled. Can be Therefore, instability of operation due to excessive load can be prevented. Further, it is not necessary to install a microcomputer capable of high-speed processing only at the slave station, and it is economical because the protection relay device can be standardized as a whole.

Embodiment 4 FIG.
12 and 13 are diagrams showing sampling synchronization processes 2 and 3 according to the fourth embodiment of the present invention.
12 and 13 show a method for correcting the timing of a sampling signal using a synchronization index pulse, which is an H / L signal having a 1 / n period of the sampling signal, generated from the GPS reception signal when the GPS signal is normal. Show.
In FIG. 12, (a) is a synchronization index pulse generated from a GPS received signal. The synchronization index pulse is a signal whose period is 1 / n of the sampling signal, but FIG. 12 shows the case where n = 1. The time when the signal rises when the signal level switches from L to H is the correct sampling signal output timing.
(B) shows a dead zone, and when the sampling signal is in the dead zone of the H level portion, the sampling signal is regarded as being transmitted at the correct timing with reference to the GPS signal, and the timing of the sampling signal is set. Do not correct.
(C) shows a sampling signal, and the position of the arrow is the sampling signal output timing. Referring to the synchronization index pulse (a) at the left sampling signal output timing, the signal level is L, so that the next sampling signal is generated with a delay of a predetermined time. In the sampling signal output timing on the right side of (c), the original timing is indicated by a broken line, indicating a state in which it is delayed by a certain correction amount.
In FIG. 13, (a), (b), and (c) show the same type of signals as in FIG. 12, and when the synchronization index pulse (a) is referenced at the sampling signal output timing on the left side of (c), the signal level is H. The next sampling signal is generated earlier by a predetermined time. In the sampling signal output timing on the right side of (c), the original timing is indicated by a broken line and indicates a state in which the correction signal is advanced by a fixed amount.
As shown in FIGS. 12 and 13, by checking the level of the synchronization index pulse each time the sampling signal is output, the sampling signal can be easily synchronized with the GPS signal by performing a certain amount of correction on the advance side or the lag side. It can be made.
12 and 13 show the case where n = 1, but if the number is n = 2 or more, it is possible to synchronize a plurality of sampling signals with a predetermined phase shift by one synchronization index pulse. I can do it.
This can be implemented even if the H / L order of the synchronization index pulse is changed.

The configuration of the fourth embodiment of the present invention is the same as the block diagram shown in FIG. 1 or FIG.
The sampling signal correction by the synchronization index pulse shown in FIGS. 12 and 13 is performed by the sampling signal output means A 106 and 206 in FIG. 1 or FIG.
The digital protection relay system according to the fourth embodiment is configured by connecting the slave station 101 or 182 and the master station 201 or 282 shown in FIG. 1 or FIG. 11, but the operation of the slave station will be mainly described.

FIG. 14 shows a flowchart 8 according to the fourth embodiment of the present invention.
FIG. 14 shows only steps 517 and 518 in FIG. 3 showing the flowchart 1 of the first embodiment of the present invention.
Step 800 in FIG. 14 indicates the start of an interrupt process in which an interrupt is generated upon receipt of a GPS signal 138 from a GPS receiver and the program is activated.
When a GPS signal reception interrupt is entered, the GPS signal abnormality timer is cleared in step 517, assuming that the GPS signal is uninterrupted and reliable, a GPS normal counter is added in step 518, and the interrupt process ends in step 819.

15 and 16 are flowcharts 9 and 10 according to the fourth embodiment of the present invention.
In FIG. 15, the operation of the slave station 101 or 182 is described.
FIG. 15 is obtained by replacing step 542 of FIG. 4 showing the flowchart 2 of the first embodiment of the present invention with steps 841 to 855.
First, in step 541, a sampling signal is output.
Next, at step 841, the level of the synchronization index pulse is read. In addition, it is read whether the sampling pulse is in the dead zone.
If it is determined in step 851 that the sampling signal is in the dead zone, the process proceeds to step 551.
If the sampling signal is outside the dead zone, it is checked in step 852 whether the level of the synchronization index pulse is H. If the level is L, the flow proceeds to step 853 and the next timer activation time is delayed by a predetermined time, and the sampling signal is The process proceeds to step 551 near the rising timing of the synchronization index pulse by the signal. When the level is H in step 852, the process proceeds to step 855, the next timer activation time is advanced by a predetermined time, and the sampling signal is similarly brought close to the rising timing of the synchronization index pulse by the GPS signal, and the process proceeds to step 551.
Steps 551 to 562 in FIG. 5 and subsequent interruptions in and after step 562 in FIG. 6 are the same as those in FIG.

FIG. 17 shows a flowchart 11 of the fourth embodiment of the present invention.
In FIG. 17, the operation of the slave station 101 or 182 is described.
FIG. 17 is obtained by replacing steps 603 to 609 in FIG. 5 showing the flowchart 3 of the first embodiment of the present invention with step 805.
In step 805, only when the GPS signal abnormality timer is smaller than the predetermined value T1, it is determined together with the determination results in steps 610 and 611, and α may be updated in steps 612 to 614. When the GPS signal abnormality timer is not less than the predetermined value T1 in step 805, the process proceeds to step 621, and the value of α is not updated.
The other steps are the same as those shown in FIGS.

In the fourth embodiment of the present invention, the sampling signal is synchronized with the GPS signal by checking the level of the synchronization index pulse that is a 1 / n period H / L signal of the sampling signal generated from the GPS signal. I can do it.
There is no need to calculate the difference between the GPS signal period and the sampling signal period, or to calculate a correction value based on the difference. By simply checking the level of the synchronization index pulse when the sampling signal is output, Synchronization to the GPS signal can be achieved by simple control of side control.
For this reason, reliability, cost, shortening of calculation time and reduction of calculation load can be expected.

Any of Embodiments 1 to 4 may be combined.
In the first to fourth embodiments, the protection relay device optimizes the timing of the sampling signal using the signal from the GPS receiver, and the third signal from the sampling signal to the data reception from the adjacent protection relay device. The delay time difference α is calculated and stored from the data communication delay time Tsm and the fourth data communication delay time Tsm from the sampling signal of the adjacent protective relay device to the data reception, and newly obtained when the GPS signal is abnormal In addition, the sampling synchronization method of the digital protection relay system that synchronizes with the sampling signal of the adjacent protection relay device from the stored values of Tms, Tsm and α has been described.

  By using this synchronization method, if the signal from the GPS receiver becomes abnormal, the sampling signal can be corrected by a simple method without major changes in the calculation method, and the adjacent protective relay can be used. Even if there is a difference in the data communication delay time between sending and receiving data with the device, the sampling signal can be corrected accurately.

1, 2, 3 Protection relay system 101 First digital protection relay device (slave station)
201 Second digital protection relay device (main station)
102, 202 A / D conversion means 103, 203 Data calculation means 104, 204 Output means 105, 205 Data communication means 106, 206 Sampling signal output means A
107 Delay time difference calculation means 108 Storage means
110 Timing difference calculation means 111 First correction means 112 and 212 Switchers 113 and 213 Reference signal generation means 114 and 214 Backup reference signal generation means 115 and 215 Second correction means 116 and 216 Sampling signal output means B
219 Third correction means 131, 231 Analog data 132, 232 Trip signal 133 First sampling signal 233 Second sampling signal 134, 234 Communication data 138, 238 GPS signal 181 First digital protection relay device (slave station)
281 Second digital protective relay (main station)
182 First digital protection relay device (slave station)
282 Second digital protective relay (main station)

Claims (13)

In the digital protection relay system in which the first and second digital protection relay devices that are connected via the transmission line and synchronize with the GPS signal and sample the amount of electricity of the power system are installed,
The first digital protective relay device is:
First sampling signal output means for outputting a first sampling signal for determining the timing for sampling the electric quantity at a predetermined period;
The first electrical quantity data sampled by the first sampling signal is transmitted to the second digital protection relay device via the first data communication path, and the second digital protection relay device side receives the second data. Data communication means for receiving the second electrical quantity data sampled by the second sampling signal output from the sampling signal output means and transmitted through the second data communication path;
The first data communication delay time from the time when the first sampling signal is output to the time when the second electric quantity data is received, and the data communication is calculated and transmitted on the second digital protection relay device side. A delay time difference calculating means for calculating a delay time difference with a second data communication delay time from the output of the second sampling signal received through the means to the reception of the first electric quantity data;
Storage means for storing the delay time difference;
When the GPS signal is abnormal, the third data communication delay time from the output of the first sampling signal to the reception of the second electric quantity data is calculated on the second digital protection relay device side. A fourth data communication delay time from the time when the second sampling signal received and received via the data communication means to the time when the first electric quantity data is received, and read from the storage means A timing difference calculating means for calculating a timing difference between the first sampling signal and the second sampling signal from the delay time difference when the GPS signal is normal;
A digital protection relay system comprising: a first correction unit that corrects the first sampling signal based on the timing difference to synchronize the first sampling signal and the second sampling signal. The delay time difference calculating means includes the first data communication delay time Td2 from the time when the first sampling signal is output to the time when the second electric quantity data is received and the first electric signal from the time when the second sampling signal is output. The delay time difference α from the second data communication delay time Td1 until the amount data is received is expressed by the equation α = Td2−Td1.
Calculate with
The timing difference calculation means is configured to calculate the third data communication delay time Tsm, the fourth data communication delay time Tms when the GPS signal is abnormal, and the delay time difference α when the GPS signal read from the storage means is normal. The timing difference ΔT between the first sampling signal and the second sampling signal is expressed by the equation ΔT = (Tms−Tsm + α) / 2.
The digital protection relay system according to claim 1, wherein the digital protection relay system according to claim 1 is operated. In the digital protection relay system in which the first and second digital protection relay devices connected through the transmission line and sampling the amount of electricity of the power system in synchronization are installed,
The first digital protective relay device is:
First sampling signal output means for outputting a first sampling signal for determining the timing for sampling the electric quantity at a predetermined period;
The first electrical quantity data sampled by the first sampling signal is transmitted to the second digital protection relay device via the first data communication path, and the second digital protection relay device side receives the second data. Data communication means for receiving the second electrical quantity data sampled by the second sampling signal output from the sampling signal output means and transmitted through the second data communication path;
The first data communication delay time from the time when the first sampling signal is output to the time when the second electric quantity data is received, and the data communication is calculated and transmitted on the second digital protection relay device side. A delay time difference calculating means for calculating a delay time difference with a second data communication delay time from the output of the second sampling signal received through the means to the reception of the first electric quantity data;
Storage means for storing the delay time difference;
A reference signal generating means for receiving a GPS signal and transmitting a reference signal;
Backup reference signal generating means for generating a backup reference signal from an internal clock signal;
Second correction means for correcting the backup reference signal by comparing with the reference signal;
When the GPS signal is normal, the reference signal is input to the sampling signal output means instead of the reference signal, and the backup signal is corrected by the second correction means when the GPS signal is abnormal. A switch,
When the GPS signal is abnormal, the third data communication delay time from the output of the first sampling signal to the reception of the second electric quantity data is calculated on the second digital protection relay device side. A fourth data communication delay time from the time when the second sampling signal received and received via the data communication means to the time when the first electric quantity data is received, and read from the storage means Timing difference calculation means for calculating a timing difference between the first sampling signal and the second sampling signal from the delay time difference when the GPS signal is normal;
A digital protection relay system comprising: a first correction unit that corrects the first sampling signal based on the timing difference to synchronize the first sampling signal and the second sampling signal. The delay time difference calculating means receives the first electric quantity data from the output of the first sampling delay time Td2 from the first sampling signal to the reception of the second electric quantity data and the second sampling signal. The delay time difference α from the second data communication delay time Td1 until the time is expressed by the equation α = Td2−Td1
Calculate with
The timing difference calculation means is configured to calculate the third data communication delay time Tsm, the fourth data communication delay time Tms when the GPS signal is abnormal, and the delay time difference α when the GPS signal read from the storage means is normal. The timing deviation amount ΔT between the first sampling signal and the second sampling signal is expressed by the equation ΔT = (Tms−Tsm + α) / 2.
The digital protection relay system according to claim 3, wherein the digital protection relay system is operated by: In the digital protection relay system in which the first and second digital protection relay devices that are connected via the transmission line and synchronize with the GPS signal and sample the amount of electricity of the power system are installed,
The first digital protective relay device is:
First sampling signal output means for outputting a first sampling signal for determining the timing for sampling the electric quantity at a predetermined period;
The first electrical quantity data sampled by the first sampling signal is transmitted to the second digital protection relay device via the first data communication path, and the second digital protection relay device side receives the second data. Data communication means for receiving the second electrical quantity data sampled by the second sampling signal output by the sampling signal output means and transmitted through the second data communication path;
The first data communication delay time from the time when the first sampling signal is output to the time when the second electric quantity data is received, and the data communication is calculated and transmitted on the second digital protection relay device side. A delay time difference calculating means for calculating a delay time difference with a second data communication delay time from the output of the second sampling signal received via the means to the reception of the first electric quantity data;
Storage means for storing the delay time difference;
When the GPS signal is abnormal, the third data communication delay time from the output of the first sampling signal to the reception of the second electric quantity data is calculated on the second digital protection relay device side. A fourth data communication delay time from the time when the second sampling signal received and received via the data communication means to the time when the first electric quantity data is received, and read from the storage means The second digital protection relay device includes timing difference calculation means for calculating and outputting a timing difference between the first sampling signal and the second sampling signal from the delay time difference when the GPS signal is normal.
The second sampling signal is corrected based on the timing difference received from the first protection relay device via the data communication means to synchronize the first sampling signal and the second sampling signal. A digital protection relay system comprising three correction means. 6. The delay time difference calculating means calculates a delay time difference from the first data communication delay time and the second data communication delay time when the GPS signal is abnormal. The digital protection relay system described in 1. When the delay time difference calculation means changes the data communication path between the first and second digital protection relay devices when the GPS signal is abnormal, the first data communication delay time and the second data communication delay time The digital protection relay system according to claim 6, wherein the delay time difference is calculated from Within a certain period after the GPS signal becomes abnormal, the delay time difference calculating means calculates the delay time difference from the first data communication delay time and the second data communication delay time, and stores the delay time difference in the storage means. The digital protection relay system according to claim 6, wherein: When the magnitude of the correction amount of the second correction means for correcting the backup reference signal by comparing with the reference signal when the GPS signal is normal is below a predetermined value, the GPS signal becomes abnormal within a certain period of time. 4. The delay time difference calculating means calculates the delay time difference from the first data communication delay time and the second data communication delay time, and the storage means stores the delay time difference. Digital protection relay system. The fixed period is determined according to the magnitude of the correction amount of the second correction means for correcting the backup reference signal by comparing the reference signal with the reference signal when the GPS signal is normal. Digital protection relay system. The correction amount of the second correction means that corrects the backup reference signal by comparing it with the reference signal when the GPS signal is normal is held separately for the fixed correction value and the variable correction value, and according to the magnitude of the variable correction value The digital protection relay system according to claim 10, wherein the predetermined period is determined. First synchronization index pulse generating means for outputting a first synchronization index pulse corresponding to the first sampling signal, and second synchronization index pulse for outputting a second synchronization index pulse corresponding to the second sampling signal Generating means,
The first and second synchronization index pulses are generated from a GPS signal having a 1 / n period of the first and second sampling signals, and the first and second sampling signals are output when the first and second sampling signal pulses are output. The first and second sampling signal output means correct a subsequent sampling timing by a predetermined amount in accordance with the levels of the second and second synchronization index pulses. The digital protection relay system according to claim 8. In the sampling synchronization method of the digital protection relay system in which the first and second digital protection relay devices connected to each other via the transmission line and synchronized with the GPS signal to sample the electric quantity are installed,
In the first digital protection relay device, the first electrical quantity data is sampled at a predetermined period in accordance with the first sampling signal, and transmitted to the second digital protection relay device in the previous period through the first data communication path,
In the second digital protection relay device in the previous period, the second electrical quantity data is sampled at a predetermined cycle in accordance with the second sampling signal, and transmitted to the first digital protection relay device through the second data communication path,
The first sampling signal is synchronized with the second sampling signal by the GPS signal,
Measuring the first communication delay time from the output of the first sampling signal to receiving the second electrical quantity data in the previous period;
Measuring a second communication delay time from the output of the second sampling signal to receiving the first electric quantity data;
Calculating a communication delay time difference from the first communication delay time and the second communication delay time and storing the difference in the storage means;
When the GPS signal is abnormal,
Measuring a third communication delay time from the output of the first sampling signal to receiving the second electrical quantity data in the previous period;
Measuring a fourth communication delay time from the output of the second sampling signal to reception of the first electric quantity data;
A shift amount between the first sampling signal and the second sampling signal is calculated from the third and fourth communication delay times and a normal communication delay time difference between the GPS signals read from the storage means, The first sampling signal is corrected to synchronize the first sampling signal and the second sampling signal.
Sampling synchronization method for digital protection relay system.

Images