JP2023048680A - protective relay system - Google Patents

Abstract

To provide a protective relay system in which each relay device can faster collect data of all the relay devices.SOLUTION: A protective relay system includes a first relay device, a second relay device and a third relay device. The first relay device generates a first communication frame including first electricity quantity data and transmits the first communication frame to the second relay device. The second relay device generates a first communication frame including first and second electricity quantity data and transmits the first communication frame to the third relay device. The third relay device generates a second communication frame including third electricity quantity data and transmits the second communication frame to the second relay device. The second relay device adds the second electricity quantity data to the second communication frame, generates a second communication frame including the second and third electricity quantity data and transmits the second communication frame including the second and third electricity quantity data to the first relay device.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to protection relay systems.

A protective relay system is provided in the power system. Protection relay systems are applied in various applications, for example, transmission line protection relay systems are known. The line protection relay system isolates fault sections upon detection of faults on transmission lines and busbars. In the transmission line protection relay system, a relay device is arranged at each terminal of the transmission line section. Each relay device measures electrical quantity data and transmits/receives a communication frame containing the electrical quantity data to/from other relay devices.

For example, Japanese Patent Laying-Open No. 11-220481 (Patent Document 1) discloses a network system including a master station and a plurality of slave stations configured by PCM current differential relays. The parent station continuously generates information frames for exchanging data among all stations. The information frame propagates down the downstream route, reaches the return station, and returns to the master station via the upstream route.

JP-A-11-220481

In a loop-shaped transmission system in which communication frames travel from the master station to the return station via the downstream route and return to the master station again via the upstream route, it takes time for the master station to collect data from all stations. The time is twice the transmission delay time between the parent station and the return station. Thus, there is a problem that it takes time for each station to collect data of all stations.

An object of one aspect of the present disclosure is to provide a technology that enables each relay device to quickly collect data of all relay devices in a protection relay system including a plurality of relay devices connected by a looped transmission line. It is to be.

According to one embodiment, a protection relay system is provided that includes a plurality of relay devices communicatively connected in a loop. The multiple relay devices include a first relay device, one or more second relay devices, and a third relay device. The first relay device includes a first generation unit that generates a first communication frame including first electrical quantity data, and a first communication unit that transmits the first communication frame to an adjacent second relay device. The second relay device includes: a second generator that adds the second electrical quantity data to the first communication frame to generate a first communication frame that includes the first and second electrical quantity data; and a second communication unit for transmitting the first communication frame including the quantity data to the adjacent second or third relay device. The third relay device includes a third generator that generates a second communication frame including third electrical quantity data, and a third communication unit that transmits the second communication frame to an adjacent second relay device. The second generator adds the second electrical quantity data to the second communication frame to further generate a second communication frame including the second and third electrical quantity data. The second communication unit further transmits a second communication frame including the second and third electrical quantity data to the adjacent second relay device or first relay device.

According to the present disclosure, in a protection relay system including a plurality of relay devices connected by looped transmission lines, each relay device can collect data of all relay devices more quickly.

1 is an overall configuration diagram of a protection relay system; FIG. FIG. 4 is a diagram for explaining arrival times of communication frames; It is a block diagram which shows an example of the hardware constitutions of a relay apparatus. FIG. 4 is a diagram for explaining a slave synchronization control method; It is a figure for demonstrating the synchronous control method during an initial period. FIG. 4 is a block diagram showing a configuration for explaining a synchronous control method during a normal period; FIG. 10 is a diagram for explaining a synchronization control method during a normal period; FIG. 5 is a diagram for explaining output timing of a trip command according to a comparative example; 4 is a diagram for explaining output timing of a trip command according to the embodiment; FIG. It is a block diagram showing an example of functional composition of a protection relay system.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<Overall composition>
FIG. 1 is an overall configuration diagram of a protection relay system. Referring to FIG. 1, protection relay system 1000 includes relay devices 11, 12A, 12B, and 13 (hereinafter collectively referred to as "relay device 10"). Each relay device 10 is a digital protection relay device, for example, a current differential relay device that performs a current differential operation. The relay device 11 functions as a master, the relay devices 12A and 12B as slaves, and the relay device 13 as a submaster. In the following description, the relay device 11 is also referred to as the "master 11", the "relay devices 12A and 12B" as the "slaves 12A and 12B", and the relay device 13 as the "submaster 13".

A plurality of relay devices 11 , 12 A, 12 B, and 13 are arranged at various locations in the electric power system and connected in a loop with a communication line 2 . The transmission speed of the communication line 2 is, for example, 1.544 Mbps. The communication line 2 may be configured by a high-speed communication network such as Ethernet (registered trademark).

Each relay device 10 measures electrical quantity data and transmits/receives a communication frame containing the electrical quantity data to/from another relay device connected to the communication line 2 . Thereby, each relay device 10 shares the electric quantity data measured by all the relay devices 10 . Each relay device 10 has two communication ports and employs two communication paths. In this embodiment, the communication route Ra is also called a downstream route, and the other communication route Rb is also called an upstream route. A plurality of relay devices 10 are connected for communication in a loop by combining upstream routes and downstream routes.

The master 11 generates a communication frame X1 including the electric quantity data M measured at its own end, and transmits it to the adjacent slave 12A. The slave 12A adds the electrical quantity data Sa measured at its own end to the communication frame X1, and transmits the communication frame X1 including the electrical quantity data M and Sa to the adjacent slave 12B. The slave 12B adds the electrical quantity data Sb measured at its own end to the communication frame X1 and transmits the communication frame X1 containing the electrical quantity data M, Sa, Sb to the adjacent submaster 13 .

On the other hand, the submaster 13 generates a communication frame X2 including the electric quantity data Ms measured at its own end, and transmits it to the slave 12B. The slave 12B adds the electric quantity data Sb to the communication frame X2 and transmits the communication frame X2 including the electric quantity data Ms and Sb to the slave 12A. The slave 12A adds the electrical quantity data Sa to the communication frame X2 and transmits the communication frame X2 including the electrical quantity data Ms, Sb, and Sa to the master 11. FIG.

In protection relay system 1000 according to the present embodiment, each relay device 10 performs calculations such as accident detection determination using electric quantity data measured at the same time. The timing for measuring the electric quantity data is determined based on the sampling pulse signal generated by dividing the hardware clock. For example, the sampling period is set to an electrical angle of 30° of the system frequency (for example, 1.67 ms for a 50 Hz system).

Typically, each relay device 10 performs a current differential operation using the electric quantity data M, Sa, Sb, Ms. Let Im, Isa, Isb, and Ims be current data corresponding to the electric quantity data M, Sa, Sb, and Ms. In this case, each relay device 10 calculates the vector sum of the current data Im, Isa, Isb, and Ims, and calculates the magnitude of the calculated vector sum as the differential current IDL. Each relay device 10 determines whether or not the differential current IDL is greater than the threshold K (that is, whether or not IDL1>K holds). When IDL>K holds, each relay device 10 determines that an accident has occurred in the protection section and outputs a trip command TS.

A backup transmission path is prepared between the master 11 and the submaster 13 . For example, if the transmission line between the slaves 12A and 12B becomes incapable of communication due to a failure, the transmission line between the slaves 12A and 12B is used as a new backup transmission line. Then, the slave 12B functions as a master, the submaster 13 functions as a slave, the master 11 functions as a slave, and the slave 12A functions as a submaster, and each relay device 10 is connected for communication in a loop using the original backup transmission path or the like to maintain the protection function. do.

FIG. 2 is a diagram for explaining arrival times of communication frames. In this embodiment, it is assumed that the transmission delay time of the communication route Ra and the transmission delay time of the communication route Rb are the same. Referring to FIG. 2, master 11 transmits communication frame X1 in synchronization with sampling timing at time t0. The communication frame X1 reaches the submaster 13 at time t3 via the slaves 12A and 12B. A communication frame X1 that reaches the submaster 13 includes electric quantity data M, Sa, and Sb.

The submaster 13 transmits the communication frame X2 in synchronization with the transmission timing of the communication frame X1 by the master 11 . The communication frame X2 reaches the master 11 at time t3 via the slaves 12B and 12A. A communication frame X2 reaching the master 11 includes electric quantity data Ms, Sb, and Sa.

As a result, the time from when the master 11 collects the electricity quantity data of its own end to when it collects the electricity quantity data of the other relay device 10 is "t3-t0", and this is the difference between the master 11 and the submaster. 13 corresponds to the transmission delay time Ta. Similarly, the time from when the submaster 13 collects the electricity quantity data of its own end to when it collects the electricity quantity data of the other relay device 10 is also Ta.

Here, in the conventional loop-shaped transmission system in which a communication frame reaches a return station from a parent station corresponding to a master via a downstream route and returns to the master again via an upstream route, the master transmits data to all stations. Let Tg be the time until data is collected. In this case, the time (that is, Ta) until master 11 according to the present embodiment collects the electric quantity data of all relay devices 10 is half the time Tg. As described above, in the present embodiment, the submaster 13, which corresponds to the return station in the conventional loop transmission system, generates the communication frame X2 including the electrical quantity data of its own end, thereby shortening the data collection time. .

<Hardware configuration>
An example in which each relay device 10 of the master 11, slaves 12A and 12B (hereinafter also collectively referred to as "slave 12"), and submaster 13 is configured based on a microcomputer will be described. Unlike the following examples, each relay device 10 may be configured based on an electronic circuit such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit). Alternatively, each relay device 10 may be configured by combining an electronic circuit such as FPGA or ASIC with a microcomputer.

FIG. 3 is a block diagram showing an example of the hardware configuration of the relay device 10. As shown in FIG. 3, relay device 10 includes auxiliary transformer 32, A/D converter 35, arithmetic processor 40, sampling pulse generator circuit 45, communication circuit 50, and digital output circuit 55 (D /O: Digital Output).

The auxiliary transformer 32 takes in the electrical quantity from the current transformer or the voltage transformer, converts it into a voltage suitable for signal processing in the relay internal circuit, and outputs it. The A/D converter 35 takes in the voltage output from the auxiliary transformer 32 and converts it into digital data. Specifically, the A/D converter 35 includes an analog filter, a sample hold circuit, a multiplexer, and an A/D converter.

The analog filter removes high-frequency noise components from the current waveform signal output from the auxiliary transformer 32 . The sample hold circuit samples the current waveform signal output from the analog filter at the period of the sampling pulse generated by the sampling pulse generating circuit 45 (that is, the sampling period). Based on the timing signal input from the arithmetic processing unit 40, the multiplexer sequentially switches the waveform signal input from the sample-and-hold circuit in time series and inputs it to the A/D converter. The A/D converter converts the waveform signal input from the multiplexer from analog data to digital data. The A/D converter outputs the digitally converted waveform signal (that is, digital data) to the arithmetic processing section 40 .

The arithmetic processing unit 40 includes a CPU (Central Processing Unit) 41 , a RAM (Random Access Memory) 42 and a ROM (Read Only Memory) 43 . Each of these elements are interconnected via a bus 44 . The arithmetic processing unit 40 may include an electrically rewritable nonvolatile memory such as a flash memory. RAM42 and ROM43 are used as main memory of CPU41. CPU 41 controls the overall operation of relay device 10 according to programs stored in ROM 43 and nonvolatile memory.

Sampling pulse generating circuit 45 includes an oscillator and a frequency dividing circuit. The oscillator outputs a reference frequency signal at a reference frequency for generating sampling pulses. The frequency dividing circuit divides the frequency of the reference frequency signal input from the oscillator by the frequency division ratio n to generate sampling pulses. Note that the frequency division ratio n of the frequency divider is controlled by the CPU 41 . This controls the frequency of sampling pulses (that is, the sampling frequency).

Communication circuit 50 communicates with other relay devices via communication line 2 . For example, the communication circuit 50 includes a media converter that converts optical signals into electrical signals and communication equipment that outputs the electrical signals to the communication line 2 . For example, the communication circuit 50 receives data from the arithmetic processing unit 40 as an optical signal via an optical fiber, converts the optical signal into an electrical signal, and transmits the data to the communication line 2 . The communication device communicates with another relay device 10 via the communication line 2 according to a prescribed protocol.

A digital output circuit 55 (corresponding to "D/O" in the drawing) is an interface circuit for outputting a signal to an external device. For example, the digital output circuit 55 outputs a trip command TS to a circuit breaker provided in the transmission line according to the command from the CPU 41 .

<Slave synchronous control method>
In the conventional loop transmission system, the sampling synchronization system is based on the premise that the communication frame is returned at the return station. However, in this embodiment, the submaster 13 corresponding to the return station transmits the communication frame at the timing synchronized with the master 11, so sampling synchronization control in the conventional loop transmission method cannot be adopted. A slave synchronization control method according to the present embodiment will be described below.

FIG. 4 is a diagram for explaining a slave synchronization control method. Here, a method for synchronizing the sampling timing of the slave 12A with the sampling timing of the master 11 will be described. Referring to FIG. 4, master 11 transmits communication frame X1 in synchronization with the sampling timing of master 11 at time t0. At time t1, the communication frame X1 reaches the slave 12A.

The submaster 13 transmits the communication frame X2 at time t0, which is the same timing as the time when the master 11 transmits the communication frame X1. In the example of FIG. 4, the sampling timings of the master 11 and the submaster 13 are synchronized, and the transmission timings of the communication frames X1 and X2 are also synchronized. At time t2, communication frame X2 reaches slave 12A.

A transmission delay time Ta (=t3-t0) between the master 11 and the submaster 13 is measured in advance and stored in at least one of the communication frame X1 and the communication frame X2. Therefore, the slave 12A can know the transmission delay time Ta when receiving at least one of the communication frame X1 and the communication frame X2. The slave 12A can also calculate the time difference Tb between the time t1 when the communication frame X1 arrives and the time t2 when the communication frame X2 arrives. Here, it is assumed that the transmission delay time of the communication route Ra and the transmission delay time of the communication route Rb are the same. The following equations (1) and (2) hold for the transmission delay time Ta and the time difference Tb.

(t2-t0)+(t1-t0)=Ta (1)
(t2-t0)-(t1-t0)=Tb (2)
Equations (3) and (4) are derived from equations (1) and (2) above.

t1-t0=Tc=(Ta-Tb)/2 (3)
t2-t0=Td=(Ta+Tb)/2 (4)
Since the transmission delay time Ta and the time difference Tb are known, the time difference Tc between the time t0 of the sampling timing of the master 11 and the time t1 when the communication frame X1 arrives, and the time difference between the time t0 and the time t2 when the communication frame X2 arrives Td is calculated. Therefore, the slave 12A determines that the sampling timing of the master 11 is the time preceding the time t1 by the time difference Tc. It should be noted that the slave 12A may determine the sampling timing of the master 11 to be the time preceding the time t2 by the time difference Td. Therefore, the slave 12A can synchronize its own sampling timing with the sampling timing of the master 11. FIG. The slave 12B also synchronizes its own sampling timing with the sampling timing of the master 11 by the same procedure.

Here, the communication frame X1 from the master 11 and the communication frame X2 from the submaster 13 are periodically transmitted. Therefore, the slave 12 needs to determine which of the communication frame X1 and the communication frame X2 has arrived earlier in terms of time.

For example, assume that the communication frames X1 and X2 are transmitted at a cycle of 20 ms, and the time difference Tb between the arrival times of the communication frames X1 and X2 is limited to within 5 ms. If the time difference Tb is within 5 ms, the slave 12 determines that the communication frame X1 from the master 11 has arrived first and the communication frame X2 from the submaster 13 has arrived later. On the other hand, when the time difference Tb is larger than 5 ms, the slave 12 determines that the communication frame X2 is the first arrival and the communication frame X1 is the second arrival.

<Synchronous control method of submaster>
Here, a control method for synchronizing the sampling timing of the submaster 13 with the sampling timing of the master 11 will be described. Here, the synchronous control method during the initial period and the synchronous control method during the normal period after the initial period will be described separately. The initial period is assumed to be a period from when the master 11 and submaster 13 are activated until a certain period of time elapses.

(initial period)
FIG. 5 is a diagram for explaining the synchronization control method during the initial period. It is assumed that the communication frames X1 and X2 are frames with a frame length of 2574 bits. Note that the slaves 12A and 12B are not shown here for ease of explanation. The example of FIG. 5 shows an example in which the sampling timing of the submaster 13 lags behind the sampling timing of the master 11 .

In the initial state, the sampling timing of the master 11 is time ta, and the sampling timing of the submaster 13 is time tc. At time ta, the master 11 transmits the communication frame X1 in synchronization with the sampling timing. At time tc, the submaster 13 transmits the communication frame X2 in synchronization with the sampling timing.

The master 11 receives the communication frame X2 at time tb. The time difference Tab between the time ta and the time tb is the time from the sampling timing of the master 11 to the time when the master 11 receives the data at the sampling timing of the submaster 13 (that is, the first bit data of the communication frame X2).

The submaster 13 receives the communication frame X1 at time td. The time difference Tcd between the time tc and the time td is the time from the sampling timing of the submaster 13 to the time when the submaster 13 receives the data at the sampling timing of the master 11 (that is, the first bit data of the communication frame X1).

The master 11 transmits the communication frame X1 including the time difference Tab at time te, which is the next sampling timing. The submaster 13 receives the communication frame X1 including the time difference Tab at time tg. The submaster 13 calculates a correction amount ΔT for synchronizing the sampling timing of the submaster 13 with the sampling timing of the master 11 based on the time difference Tab and the time difference Tcd. Here, the transmission delay time of the communication route Ra is "ΔT+Tcd", and the transmission delay time of the communication route Rb is "Tab-ΔT", which match. Therefore, the correction amount ΔT is represented by the following equation (5).

ΔT=(Tab+Tcd)/2 (5)
The submaster 13 synchronizes the sampling timing of the submaster 13 with the sampling timing of the master 11 by shortening the sampling interval (that is, the sampling period) by the correction amount ΔT. Specifically, the submaster 13 sets the sampling timing to time th. By shortening the sampling interval, the communication frame X2 transmitted from the submaster 13 at time tf includes only data from the 1st bit to the 2000th bit. As a result, this communication frame X2 does not contain 574 bits of data, and an error occurs momentarily on the master 11 side. After that, the submaster 13 performs sampling at the original sampling interval.

When the sampling timing of the sub-master 13 is earlier than the sampling timing of the master 11, the sub-master 13 lengthens the sampling interval by the correction amount ΔT so that the sampling timing of the sub-master 13 coincides with the sampling timing of the master 11. Synchronize.

(Normal period)
Even if the sampling timings of the master 11 and the submaster 13 are synchronized during the initial period, the sampling timings may gradually deviate from each other due to precision errors in the oscillators provided in each. Here, a method of synchronizing the sampling timing of the submaster 13 with the sampling timing of the master 11 in the normal period after the initial period when the sampling timing is shifted will be described.

FIG. 6 is a block diagram showing a configuration for explaining the synchronization control method during the normal period. FIG. 7 is a diagram for explaining the synchronization control method during the normal period.

Referring to FIG. 6, master 11 includes a CPU 41M, a sampling pulse generating circuit 45M and a communication circuit 50M. Communication circuit 50M includes a transmission circuit 51M and a reception circuit 52M. The CPU 41M, the sampling pulse generation circuit 45M, and the communication circuit 50M correspond to the CPU 41, the sampling pulse generation circuit 45, and the communication circuit 50 in FIG. This is the same for the submaster 13 as well.

The submaster 13 includes a CPU 41Ms, a sampling pulse generation circuit 45Ms, a communication circuit 50Ms, and a clock extraction circuit 60Ms. The communication circuit 50Ms includes a transmission circuit 51Ms and a reception circuit 52Ms. The clock extraction circuit 60Ms may be implemented by hardware or by software.

The CPU 41M of the master 11 gives the frequency dividing ratio n to the frequency dividing circuit of the sampling pulse generating circuit 45M. The frequency dividing circuit divides the frequency of the reference frequency signal input from the oscillator by the frequency division ratio n to generate a sampling pulse and supply it to the communication circuit 50M. The transmission circuit 51M transmits the communication frame X1 in synchronization with sampling timing according to the sampling pulse. Thereby, the sampling timing of the master 11 and the transmission timing of the communication frame X1 are synchronized.

The receiving circuit 52Ms receives the communication frame X1. The clock extraction circuit 60Ms extracts a clock signal from the communication frame X1. The clock extraction circuit 60Ms supplies the extracted clock signal to the transmission circuit 51Ms.

The transmission circuit 51Ms transmits the communication frame X2 at transmission timing based on the clock signal. Since this clock signal is extracted from the communication frame X1, it is a signal synchronized with the sampling timing of the master 11 and the transmission timing of the communication frame X1. Therefore, the transmission timing of the communication frame X2 transmitted from the transmission circuit 51Ms is synchronized with the sampling timing of the master 11 and the transmission timing of the communication frame X1.

Referring to FIG. 7, it can be understood that the transmission timings of the communication frame X1 and the communication frame X2 match. In this way, the communication frame X1 is transmitted in synchronization with the sampling timing of the master 11, but the communication frame X2 is not transmitted in synchronization with the sampling timing of the submaster 13. It is transmitted in synchronization with the transmission timing of the communication frame X1.

Therefore, even if the sampling timing of the submaster 13 is not synchronized with the sampling timing of the master 11, the sampling timing of the submaster 13 can be adjusted using the transmission timing of the communication frame X2. Specifically, FIG. 7 shows a configuration for gradually correcting the sampling timing deviations of the master 11 and the submaster 13 .

6 and 7, CPU 41Ms calculates the difference between the transmission timing of communication frame M2 based on the clock signal and the sampling timing based on the sampling pulse generated by sampling pulse generation circuit 45Ms. Times Ts1, Ts2, and Ts3 shown in FIG. 7 indicate the time difference between the transmission timing of the communication frame M2 and the sampling timing of the submaster 13. FIG. The example of FIG. 7 shows an example in which the sampling timing of the submaster 13 lags behind the transmission timing of the communication frame M2 (that is, the sampling timing of the master 11).

The CPU 41Ms adjusts the sampling interval based on the measured time difference Ts1. Specifically, the CPU 41Ms shortens the sampling interval by the specified time Tx. That is, "Ts2=Ts1-Tx" and "Ts3=Ts2-Tx". As a result, the time difference between the transmission timing of the communication frame M2 and the sampling timing of the submaster 13 gradually decreases, and the time difference becomes zero at time tx. When the time difference becomes zero, the CPU 41Ms stops the process of shortening the sampling interval by the specified time Tx and restores the original sampling interval. Thereby, the sampling timing of the submaster 13 and the transmission timing of the communication frame M2 are synchronized. That is, the sampling timing of submaster 13 is synchronized with the sampling timing of master 11 .

If the sampling timing of the submaster 13 is earlier than the transmission timing of the communication frame M2, the CPU 41Ms lengthens the sampling interval by the specified time Tx. When the time difference becomes zero, the CPU 41Ms stops the process of lengthening the sampling interval by the specified time Tx and restores the original sampling interval.

Typically, the CPU 41Ms executes the above sampling interval adjustment processing when the time difference between the transmission timing of the communication frame M2 and the sampling timing of the submaster 13 becomes equal to or greater than the threshold Th. The threshold Th is arbitrarily determined by the user.

According to the above method, the sampling timing can be corrected in the submaster 13 without missing bits in the communication frame.

<Shortening the trip command>
The protection relay device is configured to execute a protection relay calculation based on the electric quantity data and output a trip command when a determination result indicating that an accident has occurred is obtained multiple times. Here, in order to shorten the time from the occurrence of an accident to the output of a trip command, a configuration will be described in which electrical quantity data for a plurality of samplings are included in a communication frame.

FIG. 8 is a diagram for explaining output timing of a trip command according to a comparative example. Referring to FIG. 8, when master 11 and sub-master 13 determine that an accident has occurred, the result of the accident determination processing is "accident". The result is "normal".

A communication frame transmitted from the master 11 and the submaster 13 includes electric quantity data for one sampling. For example, a communication frame containing electrical quantity data for one sampling is transmitted every 1.67 ms.

A system fault occurs at time k1. At time k2, master 11 and submaster 13 transmit a communication frame including electricity quantity data after the occurrence of the grid fault. On the other hand, at time k2, the communication frame containing the electrical quantity data after the occurrence of the system fault has not reached the master 11 and the submaster 13, so the fault determination processing result is "normal".

At time k<b>3 , a communication frame containing electricity quantity data after the occurrence of the grid fault reaches master 11 and submaster 13 . Immediately after, at time k4, the master 11 and the submaster 13 execute protection relay calculation based on the electric quantity data after the occurrence of the system fault, and determine that the fault has occurred. At time t5, the second accident determination processing result "accident" is obtained, and at time t6, the third accident determination processing result "accident" is obtained. As a result, the master 11 and the submaster 13 output the trip command TS.

FIG. 9 is a diagram for explaining output timing of a trip command according to the present embodiment. Referring to FIG. 9, a communication frame transmitted from master 11 and submaster 13 includes electric quantity data for four samplings.

A system fault occurs at time k1. At time k2, master 11 and submaster 13 transmit a communication frame including two samplings of electricity quantity data before the occurrence of the system fault and two samplings of electricity quantity data after the occurrence of the system fault. For example, a communication frame containing electric quantity data for four samples is transmitted every 1.67 ms.

At time k3, a communication frame containing two samplings of electricity quantity data before the occurrence of the grid fault and two samplings of electricity quantity data after the occurrence of the grid fault reaches the master 11 and the submaster 13 . Immediately after, at time k4, the master 11 and the submaster 13 execute protection relay calculations based on two samplings of electricity quantity data after the occurrence of the system fault, and determine that the fault has occurred. That is, at the time t4, two times of the accident determination processing result "accident" is obtained. At time t5, the result of the third accident determination processing is "accident". As a result, the master 11 and the submaster 13 output the trip command TS.

Comparing FIGS. 8 and 9, it can be understood that a trip command can be output faster by transmitting a communication frame containing electric quantity data for a plurality of samplings, as shown in FIG. In this way, the master 11 and the submaster 13 transmit communication frames containing a plurality of electrical quantity data sampled at a plurality of sampling timings, thereby shortening the time from the occurrence of a grid fault to the output of the trip command TS. can.

<Functional configuration>
FIG. 10 is a block diagram showing an example of the functional configuration of the protection relay system 1000. As shown in FIG. In FIG. 10, for ease of explanation, the case where there is one slave 12 will be explained.

Referring to FIG. 10 , master 11 includes a first generating section 210 and a first communicating section 212 . The slave 12 includes a second generation section 220 , a second communication section 222 and a slave synchronization control section 224 . The submaster 13 includes a third generation section 230 , a third communication section 232 , a submaster synchronization control section 234 and a clock extraction section 236 . Each of these functions is implemented by a processing circuit. The processing circuit may be dedicated hardware, or may be the CPU 41 that executes a program stored in the internal memory of the relay device 10 . If the processing circuitry is dedicated hardware, the processing circuitry may be, for example, an FPGA, an ASIC, or a combination thereof.

The first generation unit 210 generates a communication frame X1 including the electric quantity data M. As shown in FIG. The first communication unit 212 transmits the communication frame X1 to the adjacent slaves 12 . Specifically, the first communication unit 212 transmits the communication frame X1 in synchronization with the sampling timing of the master 11 . The first communication unit 212 receives the communication frame X2 including the electric quantity data Ms and S from the slave 12 .

The second communication unit 222 receives the communication frame X1 including the electric quantity data M. As shown in FIG. The second generating unit 220 adds the electrical quantity data S to the communication frame X1 containing the electrical quantity data M to generate the communication frame X1 containing the electrical quantity data M and S. The second communication unit 222 transmits the communication frame X1 including the electric quantity data M and S to the adjacent submasters 13 . Note that when there are two or more slaves 12, the second communication unit 222 transmits the communication frame X1 including the electric quantity data M and S to the adjacent slaves 12. FIG.

The second communication unit 222 also receives from the submaster 13 the communication frame X2 including the electric quantity data Ms. The second generation unit 220 adds the electrical quantity data S to the communication frame X2 containing the electrical quantity data Ms to generate the communication frame X2 containing the electrical quantity data Ms, S. The second communication unit 222 transmits the communication frame X2 including the electrical quantity data Ms and S to the adjacent master 11 . Note that when there are two or more slaves 12, the second communication unit 222 transmits the communication frame X2 including the electric quantity data Ms and S to the adjacent slaves 12. FIG.

The slave synchronization control unit 224 receives the communication frame X1 at the reception timing (for example, time t1 in FIG. 4), the reception timing at which the communication frame X2 is received (for example, time t2 in FIG. 4), and the master 11 and the submaster 13 The sampling timing of the slave 12 is synchronized with the sampling timing of the master 11 based on the transmission delay time (for example, the transmission delay time Ta in FIG. 4).

The third generator 230 generates a communication frame X2 including the electrical quantity data Ms. The third communication unit 232 transmits the communication frame X2 to the adjacent slave 12 . The clock extractor 236 extracts a clock signal from the communication frame X1 transmitted at transmission timing synchronized with the sampling timing of the master 11 . The third communication unit 232 synchronizes the transmission timing of the communication frame X2 with the transmission timing of the communication frame X1 and the sampling timing of the master 11 by transmitting the communication frame X2 based on the clock signal.

The submaster synchronization control section 234 synchronizes the sampling timing of the submaster 13 with the sampling timing of the master 11 . In one aspect, submaster synchronization control section 234 executes synchronization processing in an initial period after master 11 and submaster 13 are activated.

Specifically, in the initial period, the third communication unit 232 includes the time from the sampling timing of the master 11 until the master 11 receives the data of the sampling timing of the submaster 13 (for example, the time difference Tab in FIG. 5). Receive communication frame X1. The sub-master synchronization control unit 234 calculates the time from the sampling timing of the sub-master 13 until the sub-master 13 receives the data of the sampling timing of the master 11 (for example, the time difference Tcd in FIG. 5).

The submaster synchronization control unit 234 synchronizes the sampling timing of the submaster 13 with the sampling timing of the master 11 based on the time difference Tab and the time difference Tcd. Specifically, submaster synchronization control section 234 calculates correction amount ΔT for synchronizing the sampling timing of submaster 13 with the sampling timing of master 11 based on the difference between time difference Tab and time difference Tcd. The submaster synchronization control unit 234 synchronizes the sampling timing of the submaster 13 with the sampling timing of the master 11 by adjusting the sampling interval of the submaster 13 by the correction amount ΔT.

In another aspect, the sub-master synchronization control section 234 performs synchronization processing during the normal period after the initial period. Specifically, the sub-master synchronization control unit 234 calculates the difference between the transmission timing of the communication frame X2 and the sampling timing of the sub-master 13 (for example, time Ts1 in FIG. 7) during the normal period. The submaster synchronization control unit 234 synchronizes the sampling timing of the submaster 13 with the sampling timing of the master 11 by adjusting the sampling interval of the submaster 13 based on the difference.

Note that the first generator 210 may generate the communication frame X1 including a plurality of electrical quantity data M sampled at a plurality of sampling timings. In this case, the first communication unit 212 transmits a communication frame X1 including a plurality of electrical quantity data M. Similarly, the third generator 230 may generate a communication frame X2 including a plurality of electrical quantity data Ms sampled at a plurality of sampling timings. In this case, the third communication unit 232 transmits a communication frame X2 including a plurality of electrical quantity data Ms.

<Advantages>
According to this embodiment, in a protection relay system including a plurality of stations connected by a looped transmission line, each relay device can collect data of all relay devices more quickly. Since a looped transmission line is used, communication equipment costs can be reduced. Even if the number of relay devices increases, the accuracy of sampling synchronization can be maintained as compared with the case of adopting a facing type transmission line.

Other embodiments.
The configuration illustrated as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and part of the configuration may be omitted without departing from the gist of the present invention. , can also be modified and configured. Further, in the above-described embodiment, the processing and configuration described in other embodiments may be appropriately adopted and implemented.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

2 communication line, 10 relay device, 11 master, 12A, 12B slave, 13 submaster, 32 auxiliary transformer, 35 A/D converter, 40 arithmetic processing unit, 42 RAM, 43 ROM, 44 bus, 45 sampling pulse generation circuit , 50 communication circuit, 51M, 51Ms transmission circuit, 52M, 52Ms reception circuit, 55 digital output circuit, 60Ms clock extraction circuit, 210 first generation unit, 212 first communication unit, 220 second generation unit, 222 second communication unit , 224 slave synchronization control unit, 230 third generation unit, 232 third communication unit, 234 sub-master synchronization control unit, 236 clock extraction unit, 1000 protection relay system.

Claims (8)

A protective relay system including a plurality of relay devices communicatively connected in a loop,
The plurality of relay devices includes a first relay device, one or more second relay devices, and a third relay device,
The first relay device is
a first generation unit that generates a first communication frame including the first electrical quantity data;
a first communication unit that transmits the first communication frame to the adjacent second relay device,
The second relay device is
a second generator that adds second electrical quantity data to the first communication frame to generate the first communication frame including the first and second electrical quantity data;
a second communication unit that transmits the first communication frame including the first and second electrical quantity data to the adjacent second relay device or the third relay device;
The third relay device is
a third generating unit that generates a second communication frame including the third electrical quantity data;
a third communication unit that transmits the second communication frame to the adjacent second relay device;
The second generation unit adds the second electrical quantity data to the second communication frame to further generate the second communication frame including the second and third electrical quantity data,
The protection relay system, wherein the second communication unit further transmits the second communication frame including the second and third electrical quantity data to the adjacent second relay device or the first relay device. The third relay device further includes a third relay synchronization control unit that synchronizes the third sampling timing of the third relay device with the first sampling timing of the first relay device,
The third relay synchronization control unit is
In an initial period after the first and third relay devices are activated, the first relay device receives the data of the third sampling timing of the third relay device from the first sampling timing of the first relay device. The third sampling timing is determined based on a first time until reception and a second time from the third sampling timing until the third relay device receives the data at the first sampling timing. 2. The protection relay system of claim 1, synchronized with the first sampling timing. The third relay synchronization control unit is
calculating a correction amount for synchronizing the third sampling timing with the first sampling timing based on the difference between the first time and the second time;
3. The protection relay system according to claim 2, wherein the third sampling timing is synchronized with the first sampling timing by adjusting the sampling interval of the third relay device by the correction amount. a first transmission timing at which the first communication unit transmits the first communication frame and a second transmission timing at which the third communication unit transmits the second communication frame, and
The first sampling timing is synchronized with the first transmission timing,
The second relay device has a first reception timing at which the first communication frame is received, a second reception timing at which the second communication frame is received, and a time interval between the first relay device and the third relay device. 4. The protection relay system according to claim 2, further comprising a second relay synchronization control section for synchronizing the second sampling timing of the second relay device with the first sampling timing based on the transmission delay time. The third relay device further includes a clock extraction unit that extracts a clock signal from the first communication frame transmitted at the first transmission timing synchronized with the first sampling timing,
5. The third communication unit according to claim 4, wherein the second transmission timing is synchronized with the first transmission timing and the first sampling timing by transmitting the second communication frame based on the clock signal. protection relay system. The third relay synchronization control unit is
calculating a difference between the second transmission timing and the third sampling timing in a normal period after the initial period;
6. The protection relay system according to claim 5, wherein the third sampling timing is synchronized with the first sampling timing by adjusting the sampling interval of the third relay device based on the difference. The first communication unit transmits the first communication frame including a plurality of the first electric quantity data sampled at a plurality of the first sampling timings,
The third communication unit transmits the second communication frame including a plurality of the third electrical quantity data sampled at a plurality of the third sampling timings, respectively. A protective relay system as described in . Each of the first to third relay devices is a current differential relay device that performs a current differential operation using the first to third electrical quantity data. protection relay system as described above.

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