JP2006246680A - Pcm current differential guard relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform sampling synchronization of a PCM current differential relay with accuracy at high speed when transmission error is restored. <P>SOLUTION: Two or more PCM current differential relays 16A-16C are provided in accordance with two or more terminals, which constitute a protecting sections of a power cable 11. In each PCM current differential relay, a current of the power cable at self terminal is subjected to sampling and converted to a PCM signal, and each PCM signal is transmitted and compared with each other through the transmission line so that a failure in the protecting section is detected in the PCM current differential relay. The sampling synchronization operation of current with another PCM current differential relay at another terminal can be performed by one PCM current differential relay, which is provided in accordance with one terminal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a PCM current differential protection relay device, and more particularly to a technique for performing sampling synchronization matching at the time of transmission error of PCM signals transmitted between a plurality of terminals in a protection target section at high speed.

  The PCM current differential relay is installed, for example, at terminals at both ends of a predetermined section of the transmission line, detects a transmission line current at each terminal, converts it into a PCM signal, and transmits it to each other. The terminal PCM signal is compared, and if they match within the allowable range, it is determined that the transmission line in the section is normal. On the other hand, if the value exceeds the allowable value and does not match, it is determined that the transmission line accident is in the relevant section, and the circuit breakers provided at both ends of the relevant section are opened to disconnect the transmission line in the accident section. . In such a PCM current actuated relay, the transmission line current sampling at each terminal needs to be performed by synchronous sampling with the same absolute time.

  For example, in the PCM current actuated relay described in Patent Document 1, for synchronous sampling, the reference signal of its own terminal is transmitted to the other terminal via the information transmission device, and the transmission time is stored. deep. Next, the reception time of the reference signal transmitted from the counterpart terminal is counted, and the time difference from when the self terminal transmits the reference signal until the reference signal of the counterpart terminal is received is obtained. Then, the time difference is transmitted to each other, the transmission timing of the reference signal is adjusted so that the time difference is the same, and a synchronous sampling clock in which the absolute times of the own terminal and the counterpart terminal coincide is generated. Further, in the case of a synchronous system that generates a synchronous sampling clock having the same absolute time due to the time difference between the transmission and reception of the reference signal as described above, the line route of the transmission path between the terminals is not necessarily the same. Therefore, there is a case where the transmission time differs and synchronization may not be achieved. Therefore, the transmission line current is sampled with the sampling clock synchronized with the phase of the transmission line current, and the PCM signal is generated with the frame configuration synchronized with the phase of the transmission line current. It has been proposed to obtain synchronization in which the absolute time coincides between the own terminal and the counterpart terminal by transmitting and receiving and comparing the frame synchronization.

Japanese Patent Laid-Open No. 11-41790

  However, recently, it may be difficult to construct a new highly reliable dedicated optical transmission line due to the restrained capital investment of communication devices such as information transmission devices. Application of a transmission line (for example, transmission capacity: 9.6 kbps) is being studied.

  However, when a low-speed transmission path or the like is used, the occurrence of transmission errors is relatively greater than that of dedicated optical transmission. However, Patent Document 1 does not consider synchronization recovery when a transmission error occurs. Note that synchronization recovery when a transmission error occurs also becomes a problem when a high-speed transmission path (for example, transmission capacity: 54 kbps / 1.5 Mbps) is used.

  Therefore, it is desired to develop a highly reliable protection device by improving the operating rate of the PCM current differential relay by calculating sampling synchronization at the time of transmission error recovery with high speed and accuracy.

  An object of the present invention is to perform sampling synchronization of a PCM current differential relay at a high speed with high accuracy when a transmission error is recovered.

  In order to solve the above-described problem, the present invention provides a plurality of PCM current differential relays corresponding to a plurality of terminals constituting the protection target section of the transmission line, and each PCM current differential relay is provided at its own terminal. In the PCM current differential relay device for detecting an accident in the section to be protected by sampling the current of the power transmission line, converting it into a PCM signal, and transmitting and comparing the signals through a transmission line, one terminal The current sampling synchronization processing is executed with the other PCM current differential relay provided at the other terminal by the one PCM current differential relay provided corresponding to To do.

  That is, according to the present invention, sampling synchronization processing with other PCM current differential relays is performed by one PCM current differential relay without performing sampling synchronization processing among a plurality of PCM current differential relays. In other words, by providing each PCM current differential relay device with a sampling synchronization control circuit that is one less than the number of terminals, sampling synchronization processing is simultaneously performed between the PCM current differential relay devices. Since it is executed, sampling synchronization can be performed at high speed and with high accuracy.

  For example, when the transmission line protection target section is applied to three or more terminals, it is only necessary to execute sampling synchronization processing with a plurality of other PCM current differential relays by one PCM current differential relay. Therefore, sampling synchronization of PCM current differential relays provided at three or more terminals can be performed at high speed and with high accuracy.

  Therefore, according to the present invention, even when a low-speed transmission path or the like is applied and the transmission error is higher than that of the dedicated optical transmission path and the transmission path is low in reliability, high-speed synchronous pull-in is possible when the transmission error is recovered. It is possible to protect at high speed and with high accuracy in the event of a cable accident. Even when applied to an optical transmission line, the same effect can be obtained.

  According to the present invention, sampling synchronization of the PCM current differential relay at the time of transmission error recovery can be performed at high speed and with high accuracy.

  Hereinafter, the present invention will be described based on embodiments. FIG. 1 is a single line diagram showing a three-phase AC power transmission line to which a PCM current differential relay device according to an embodiment of the present invention is applied. As illustrated, the present embodiment is an example in which the PCM current differential relay device of the present invention is applied to a three-terminal transmission line. As shown in the figure, the terminals A, B, and C of the three-terminal transmission line 11 are power supply terminals connected to the three-phase AC power supplies 12A, 12B, and 12C, respectively. Circuit breakers 13A, 13B, and 13C are provided on the power transmission lines of the terminals A, B, and C, respectively, and are connected to the power supply system when the circuit breakers 13A, 13B, and 13C are “ON”.

  Further, on the power source side of the circuit breakers 13A, 13B, and 13C, voltage transformers 14A, 14B, and 14C that detect the voltage of the transmission line at the terminals A, B, and C, and a current transformer 15A that detects the current of the transmission line. , 15B, 15C are provided, and the voltage and current detected thereby are respectively input to the corresponding PCM current differential relay devices 16A, 16B, 16C. The PCM current differential relay devices 16A, 16B, and 16C are configured to include a PCM current differential relay and a communication device. The communication device of the PCM current differential relay device 16A is connected to the communication device of the PCM current differential relay device 16B via the signal transmission path 17, and the communication device of the PCM current differential relay device 16C is connected to the signal transmission path 18. It is connected. The communication device of the PCM current differential relay device 16B is connected to the communication device of the PCM current differential relay device 16C via the signal transmission path 19.

  The PCM current differential relay devices 16A, 16B, and 16C are configured to include blocks of control 1, control 2, and control 3, respectively, as shown in FIG. The control 1 of the PCM current differential relay device 16A is connected to the control 1 of the PCM current differential relay device 16B via the signal transmission line 17, and the control of Tm = Ts1 is performed so that the A terminal and the B terminal are similarly locked. An operation is being performed. The control 2 of the PCM current differential relay device 16A is connected to the control 1 of the PCM current differential relay device 16C via the signal transmission path 18, and performs a control calculation of Tm = Ts2. The control 3 of the PCM current differential relay device 16A controls the sampling clock of the analog input of its own device based on the calculation results of the control 1 and the control 2. The control 2 of the PCM current differential relay device 16B is connected to the control 2 of the PCM current differential relay device 16C via the signal transmission path 19. Here, Tm is a sampling timing (measured value) of the A terminal (reference terminal), and Ts1 and Ts2 indicate sampling timings of the B terminal and the C terminal, respectively. Therefore, by controlling Tm = Ts1 = Ts2, the sampling clocks coincide at all ends of the PCM current differential relay devices 16A, 16B, and 16C.

  Each PCM current differential relay device 16A, 16B, 16C takes in the voltage of the transmission line from the corresponding voltage transformer 14A, 14B, 14C, respectively, and determines whether the accident of the transmission line 11 is a short-circuit accident or a ground fault. It is configured to perform voltage calculation for discrimination. When a failure occurs in the transmission line, current is taken from the current transformers 15A, 15B, and 15C, and the vector sum of the currents IA, IB, and IC flowing through the terminals A, B, and C is calculated. Unless IA-IB-IC = 0, it is determined that the failure is in the transmission line 11 (in the protection target section), and the circuit breakers 13A, 13B, and 13C are set to “OFF” to protect the transmission line system. It has become.

  As shown in FIG. 2, the present embodiment is characterized in that the PCM current differential relay devices 16A, 16B, and 16C have the PCM current differential relay device 16A as a representative terminal and the PCM current differential relay devices 16B, 16C, as shown in FIG. In other words, sampling synchronization processing is executed at the same time. That is, the sampling synchronization processing is executed so that Tm = Ts1 between the PCM current differential relay devices 16A and 16B and simultaneously Tm = Ts2 between the PCM current differential relay devices 16A and 16C. . At the same time, the PCM current differential relay devices 16B and 16C use the PCM current differential relay device 16B as a representative terminal and execute sampling synchronization processing with the PCM current differential relay device 16C. There is. That is, the sampling synchronization processing is executed between the PCM current differential relay devices 16B and 16C so that Ts1 = Ts2.

  Thus, according to the present embodiment, each PCM current differential relay device is provided with the sampling synchronous control circuit of control 1 and 2 that is one less than the number of terminals, so that the PCM current differential relay device 16A, Sampling synchronization processing can be executed simultaneously between the three parties 16B and 16C. As a result, even if there is a transmission error, it is possible to perform synchronous pull-in at high speed, and it is possible to minimize the synchronous pull-in time at the time of transmission error recovery, and apply a transmission line that is highly likely to cause a transmission error. However, it is possible to detect a transmission line accident with high accuracy by calculating the difference current.

  FIG. 3 is a flowchart showing the sampling synchronization processing and the current differential relay processing procedure. The illustrated flowchart shows the processing of the PCM current differential relay device 16A. First, in step S1, sampling synchronous control of the PCM current differential relay device of terminal A and terminal B is performed. That is, the control clock (Tm) at the end and the control clock (Ts1) at the B terminal are calculated. Ts1 is calculated from the transmission reception data. At the same time, sampling synchronous control of the PCM current differential relay device of terminal A and terminal C is performed in step S2. That is, the control clock (Tm) at its own end and the control clock (Ts2) at the C terminal are calculated. Ts2 is calculated from the transmission reception data. Next, in steps S3 and S4, whether or not the controlled sampling synchronization is established is confirmed by whether or not the difference between Tm, Ts1, and Ts2 is within a specified value. If the synchronization is normal, 87 relays are performed in step S5. Perform the operation. Next, in step S6, it is determined whether the accident is in the power transmission line 11. If the accident is in the power transmission line 11, in step S7, a break command is output to the circuit breaker 13A. In addition, the process of step S5-S7 performs the same process also in the other PCM current differential relay devices 16B and 16C.

  Although not shown, the PCM current differential relay device 16B also performs sampling synchronization control with the PCM current differential relay device 16C as described with reference to FIG.

  As described above, according to the present embodiment, it is possible to establish sampling synchronization at high speed even on a low-speed transmission path or a high-speed transmission path (54 kbps, 1.544 Mbps). As a result, the operating rate of the PCM current differential relay is improved, and the reliability of the protection relay is improved.

  In the embodiment of FIGS. 1 and 2, the three-terminal system has been described. However, the present invention is not limited to this, and a sampling synchronization control circuit that is one less than the number of terminals is also used in a transmission line system having four or more terminals. By implementing it, it is possible to pull in sampling synchronization at high speed.

  As described above, according to the present embodiment, a PCM current differential protection relay having a high section determination capability can be applied even in a transmission line that has a high possibility of occurrence of a transmission error, such as a low-speed transmission line, and its operating rate. Therefore, stable power supply is possible.

It is a figure which shows the system | strain structure of the three-phase alternating current power transmission line with which the PCM current differential relay apparatus of one Embodiment of this invention was applied. It is a figure which shows the functional block structure which concerns on the characteristic part of the PCM current differential relay apparatus of one Embodiment of this invention. It is a flowchart which shows the process sequence of a PCM current differential relay apparatus.

Explanation of symbols

11 Transmission line 12A, 12B, 12C Three-phase AC power supply 13A, 13B, 13C Breaker 14A, 14B, 14C Voltage transformer 15A, 15B, 15C Current transformer 16A, 16B, 16C PCM current differential relay device 17, 18, 19 Signal transmission path

Claims (2)

  A plurality of PCM current differential relays are provided corresponding to a plurality of terminals constituting the protection target section of the power transmission line, and each PCM current differential relay samples the current of the power transmission line at its own terminal to generate a PCM signal. One PCM current provided corresponding to one terminal in a PCM current differential relay device that detects an accident in the protection target section by converting, transmitting and comparing with each other via a transmission line The PCM current differential relay device, wherein the current sampling synchronization processing is executed with another PCM current differential relay provided at another terminal by a differential relay.   The protection target section of the power transmission line has three or more terminals, and one PCM current differential relay executes sampling synchronization processing of the current with another PCM current differential relay. Item 4. The PCM current differential relay device according to Item 1.

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