JP2003153428A - Protection relay system, communication apparatus, and protection relay method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve mutual communication between a plurality of electrical stations by synchronizing the electric stations by utilizing a clock signal from a GPS, by speedily communicating an accident signal between the electrical stations via a power line at the same timing and with the same number of clocks. SOLUTION: The protection relay system 10 is provided for each of the electric stations A and B, and is connected via the power line 20. The protection relay system 10 judges the generation of an accident in the power line 20 by detecting the direction of current in the electric stations A and B. Then, when it is judged that an accident has occurred, a relay 14 at the electric station A transmits a trip signal for breaking the electric station A from the power line 20 to a CB 11, and transmits an accident signal for reporting the generation of the accident at the power line 20 to a communication apparatus 15. The communication apparatus 15 receives a clock signal from the GPS, synchronizes a clock that is clocked based on the clock signal, and mutually communicates the accident signal from the relay 14 at the same timing and with the same number of clocks among the electrical stations via the power line 20.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a protective relay system, a communication device, and a protective relay method, and more particularly to a GP.
S (Global Positioning System)
The present invention relates to a protection relay system and a protection relay method using a communication device that enables mutual communication by independent synchronization using a clock signal from em).

[0002]

2. Description of the Related Art Conventionally, as a protection relay system in a protection relay system for protecting a power system, for example,
The phase comparison method mainly applied to the system of 275 kV or more, which detects the phase of the current waveform at both ends of the power line, and the accident determination by detecting the current direction at both ends of the power line, mainly of 154 kV or more A current direction comparison method applied to a power system is known. This current direction comparison method detects the direction of the current at each electric station in the power system, determines the faulty section of the power line between the electric stations based on the detected current direction, and the result of the determination,
When it is determined that an accident has occurred, the corresponding section is blocked by the CB (circuit breaker) of each electric station. This current direction comparison method allows the system to be constructed at a relatively low cost as compared with the phase comparison method described above. Here, the electric station means a power station, a substation, or the like in the electric power system, and indicates a facility for transmitting and receiving electric power through the electric power line.

When an accident occurs in an electric power system having a protection relay system based on the current direction comparison method, an electric station (the electric power station on the end side) from which the accident is determined to an electric station (an electric station on the other end side) adjacent to the electric station. , An accident signal for notifying that an accident has occurred is transmitted from a communication device of each electric station via a power line. However, in the method of transmitting an accident signal using a power line, particularly a transmission line extending over a long distance as a transmission line, different carrier frequencies are simultaneously transmitted, so a filter for preventing the carrier frequency from wrapping around and extracting the carrier wave, etc. There were severe restrictions on the characteristics of the analog circuits that compose the. Further, when transmitting the modulated signal, there is a problem that high-speed transmission is difficult because the frequency band of the power line and the frequency band of the coupling device are narrow. Further, when transmitting and receiving an accident signal through a power line, in a mode in which the self-end side electric station and the other end side electric station correspond one to one, the communication devices installed at both ends send out different frequencies and the accident occurs. Although signals are transmitted and received, in a form in which another power transmission line branches from the middle of the power transmission line, it is necessary to detect an accident in each section, so the number of installed communication devices increases. For example, in the case of T branch, a maximum of 6 communication devices are required. In such a case, there is a method in which one communication device is installed for each terminal and a station address, header, etc. are added to the accident signal to be transmitted to identify the other station's electric station. Since high-speed transmission is difficult, it takes a long time to exchange signals, which is not applicable to a protective relay system.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and utilizes a clock signal from GPS to synchronize communication devices at each electric station to alternately transmit and receive timing. In addition, by using the same number of clocks, fault signals transmitted and received between electric stations can be superimposed on the power line to enable high-speed communication even on a transmission line with a narrow frequency band such as the power line, and communication between multiple electric stations. It was made for the purpose of mutually enabling.

[0005]

According to a first aspect of the present invention, there is provided a protective relay system for each electric station in an electric power system for transmitting and receiving electric power between two or more electric stations via a power line, and each protection is provided. The relay system determines whether or not an accident has occurred in the power line between the electric stations based on the electric quantity detected by the detecting means for detecting a predetermined electric quantity at the electric station and the electric quantity detected by the detecting means. Determination means,
As a result of the judgment by the judging means, when it is judged that an accident has occurred, the trip signal for shutting off the electric power station from the power line and the occurrence of the accident on the electric power line between the electric power stations are adjacent to each other. A protective relay that outputs an accident signal for notifying an electric station, a circuit breaker that disconnects the electric station from the power line based on a trip signal from the protective relay, and a clock signal from GPS A GPS receiver, timing means for timing based on a clock signal received from GPS by the GPS receiver, and an accident signal from the protective relay based on the clock timed by the timing means via the power line. At least a communication device for transmitting and receiving between the adjacent electric stations, and synchronizing the clock of the communication device of the adjacent electric station by the timing means The accident signal can be transmitted / received between the two or more electric stations via the power line at alternate timings and with the same number of clocks. .

According to a second aspect of the present invention, in the protective relay system according to the first aspect, at least a current is detected as the predetermined amount of electricity, and an accident is determined based on the direction of the detected current. It is characterized by.

According to a third aspect of the present invention, in the protective relay system according to the first or second aspect, the alternate timing of the transmission and reception is a superposed wave having the same number of clocks as the transmission path length between the electric stations. It is characterized in that the time is set to be equal to or longer than the time determined based on the number of (carrier wave) transmission cycles.

According to a fourth aspect of the present invention, in the protective relay system according to any one of the first to third aspects, when the communication device transmits the accident signal via the power line, the accident signal is transmitted. The phase angle of the carrier frequency is repeatedly controlled according to a predetermined number of transmission cycles so that the phase angle of the carrier frequency starts from 0 degree and ends at 360 degrees (1 cycle). The communication device of the adjacent electric station receives the accident signal via a time filter set to a time width based on the alternate timing of the transmission and reception. Is.

According to a fifth aspect of the present invention, in the protective relay system according to any one of the first to fourth aspects, the communication device has a plurality of different superimposing waves (carrier waves) having the same number of clocks. And a code assigning unit that assigns a code created in advance to each of the set sending cycle numbers, and the clocking unit synchronizes the clocks of the communication devices of the adjacent electric stations to transmit and receive. The codes assigned by the code assigning means can be mutually transmitted and received between the two or more electric stations via the power line at alternate timings and using the same number of clocks. It is a thing.

According to a sixth aspect of the present invention, in the protection relay system according to the fifth aspect, the code created in advance is
Characterized by including at least a constant code for monitoring the operating conditions at each electric station, an inspection code for checking the operating conditions at each electric station, and an accident code sent when an accident occurs. Is.

According to a seventh aspect of the present invention, in the protective relay system according to any one of the first to sixth aspects, the communication device receives the superimposed wave (carrier wave) having the same clock number, It is characterized in that at least one or a plurality of time width, amplitude, gradient, and area in one cycle of the received superimposed wave (carrier wave) is detected.

According to an eighth aspect of the present invention, in the protective relay system according to any one of the first to seventh aspects, the communication device is capable of transmitting and receiving signals among three or more electric stations. It is a feature.

According to a ninth aspect of the present invention, in the protective relay system according to any one of the first to eighth aspects, the communication device transmits a superimposed wave (carrier wave) having the same number of clocks through the power line. In this case, one cycle or more of the number of clocks of the superimposed wave (carrier wave) is set as one symbol, and the set one symbol is transmitted as at least one bit.

A tenth aspect of the present invention is a communication device in the protective relay system according to any one of the first to ninth aspects.

An eleventh aspect of the present invention is a protective relay method for each electric station in an electric power system for transmitting and receiving electric power between two or more electric stations via a power line, which is predetermined in the electric station. And a determination step of determining whether or not an accident has occurred in the power line between the electric power stations based on the detected amount of electricity, and as a result of the determination, an accident has occurred. When judged, an accident signal output step of outputting an accident signal for notifying an adjacent electric station that an accident has occurred in the power line between the electric stations, and the adjacent adjacent signal corresponding to the output accident signal. A reception signal confirmation step of confirming a reception signal from the electric station, a clock signal reception step of receiving a clock signal from GPS, and timekeeping based on the clock signal received from the GPS are performed. A time step, a transfer step of transferring the accident signal to a relay side at the same timing as the adjacent electric station based on the clocked clock, and the electric station being adjacent to the electric station based on the transferred accident signal A trip signal transmitting step for transmitting a trip signal for disconnecting an electric station from the electric power line, wherein the clock of the communication device of the adjacent electric station is the clock from the GPS in the accident signal outputting step. The accident signal can be mutually transmitted / received between the two or more electric stations via the power line by using the same number of clocks and transmitting / receiving in synchronization with each other based on a signal. It is what

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an outline of a protective relay system based on a current direction comparison method, in which an electric station A and an electric station B each have a protective relay system 10. The electric stations A and B are connected via a power line 20. The protective relay system 10 includes a CB (circuit breaker) 11,
CT (current transformer) 12, CC (coupling capacitor) 13, R
It has at least y (protective relay, relay) 14 and communication device 15. The arrows shown in Fig. 1 indicate the electrical stations A and B at both ends.
In the present example, when the power system is normal (normal time), a current flows from the electric power station B to the electric power station A in a state where the CB 11 is closed, and the electric power line 20 is connected to the electric power line 20. When an accident occurs (at the time of accident), the electric current in the electric station A flows in the opposite direction, and the CB 11 is opened. This is because, for example, the current flowing from the electric power station B side to the electric power station A due to an accident due to a ground fault in the electric power line 20 is cut off, and the other end side of the electric power station A (the opposite side to the electric power station B) is connected. This is a state in which a current from an electric station (not shown) is being supplied.

In the protective relay system based on the current direction comparison method, the current direction at the electric station at both ends of the power line 20 is detected by, for example, the CT 12 at the electric station A side, and Ry is detected.
14 determines an accident based on the detected current direction, and transmits an accident signal to the communication device 15 when an accident is determined.
The communication device 15 at the electric station A receives the accident signal from the Ry 14, superimposes the accident signal on the power line 20, and sends the electric signal to the electric station B. Furthermore, since the communication device 15 on the side of the electric station A and the communication device 15 on the side of the electric station B can output an accident signal to each Ry14 at the same timing, the Ry14 of each of the electric stations A and B is , C
A trip command for shutting off B11 can be simultaneously output. At this time, the output timing (cutoff timing) of the accident signal is not limited to the same timing as described above, and it is also possible to make the order of the electric station A → the electric station B or the order of the electric station B → the electric station A. Is.
In this case, for example, Ry14 on the electric power station side that detected the accident
Thus, it is possible to output a trip command to the CB 11 at the self-end and send an accident signal to the communication device 15 at the other end electric station. Thus, for example, in a power system in which power lines are connected in a loop, by providing the protective relay system 10 at each electric station, the spread of abnormalities to other electric stations is prevented and the entire power system is cut off. It is possible to prevent this.

FIG. 2 is a block diagram for explaining the configuration of the protection relay system 10 based on the current direction comparison method according to the embodiment of the present invention. Protection relay system 10
Has a CB 11, a CT 12, a CC 13, a Ry 14, a communication device 15, a BC (blocking coil) 16, and a CF (coupling filter) 17. In this example, a case will be described in which an accident occurs in the power line 20 that connects the electric station A and the electric station B, and the accident is detected at the electric station A. Here, the electric station B has the same system configuration as the electric station A, and even when an accident is detected at the electric station B, the same processing as the electric station A can be performed.
Normally, in a loop power system, the electric station near the power source is the master (master station), and the electric station on the far side is the slave (slave station).
As an example, when an accident occurs in the power system, the master (master station) on the side closer to the power supply is shut off, but any form is possible depending on the setting.

The CT 12 of the protective relay system 10 at the electric station A detects a predetermined amount of electricity at the electric station A. Here, in the case of the current direction comparison method, C
T12 has a function of detecting a current as a predetermined quantity of electricity and monitoring the direction of the detected current. CT
12 sends a signal indicating the direction of current to Ry 14. The Ry 14 determines whether or not an accident has occurred in the power line 20 between the electric stations based on the signal indicating the direction of the current sent from the CT 12 and the voltage / current value obtained by other means. As a result of the determination, when the direction of the current is opposite to the normal direction, it is determined that an accident (internal accident) has occurred in the sections A and B, and the electric station A is connected to the power line 20.
From the electric power line 20 between the electric power stations A and B, and an accident signal for notifying the adjacent electric power station B that an accident has occurred. CB11 is an R to cut off the power station A or the power station B from the power line 20.
Electrical station A based on the trip signal sent from y14
Alternatively, it is a circuit breaker that disconnects the electric station B from the power line 20.
The communication device 15 of the present invention includes a GPS receiver for receiving a clock signal from GPS and a G receiver by the GPS receiver.
The communication device 15 on the electric station B side uses the clock that counts time based on the clock signal received from the PS and the clock that counts time.
It has a function of transmitting and receiving the accident signal from the Ry 14 between the electric stations A and B through the electric power line 20 in synchronization with the clock of. The high frequency from the communication device 15 is CB in the BC 16.
This is to prevent backflow to the 11 side.

The protective relay system 10 according to the present invention is
By incorporating the communication device 15 into the system, each electric station can independently ensure synchronization by the clock signal from the GPS and the synchronization of the entire system can be ensured. Therefore, an accident signal between a plurality of electrical stations can be obtained. You will be able to send and receive each other. Further, since it is possible to synchronize a plurality of electric stations, it is possible to perform mutual transmission and reception without adding a station address, a header, etc., and it is possible to simplify the communication protocol. Further, as the carrier wave, the same clock frequency is superimposed on the power line 20 and is carried without being modulated,
High-speed transmission can be realized even with a power line having a narrow frequency band without being restricted by the frequency band.

FIG. 3 shows a communication device 15 to which the present invention is applied.
2 is a diagram for explaining the schematic structure of the communication device 15 in FIG.
Is a receiver 15a, an A / D (analog / digital converter) 15b, a DSP (digital signal processor) 15c, P
It has an IO (input / output device) 15d, an MPU (microprocessor) 15e, a transmitter 15f, a GPS receiver 15g, and a power supply 15h. By incorporating this communication device 15 into the protection relay system 10 described above, a plurality of electric stations are synchronized with each other at the same transmission / reception timing and the same number of clocks based on the clock signal from the GPS. It is possible to communicate.

Further, the communication device 15 can be applied to other than the protective relay system in the electric power system.
It can also be applied to a communication system for various data and the like via a power line. This enables the communication device 15 to transmit and receive data and the like from an electric station located at a remote place via a power line. Moreover, various meters of electricity, gas, water, etc. are read using a personal computer or the like installed in a home or a company, and the read data is transmitted from the communication device 15 to each jurisdiction company or the like via a power line. Such usage forms are also possible. The communication device 15 is not limited to the power line, and may be applied to a communication line other than the power line, such as a communication cable, a coaxial cable, an optical fiber cable or the like.

FIG. 4 is a block diagram for explaining an internal configuration example of the communication device 15 shown in FIG. Communication device 15
Is ANT (antenna) 150, REC (GPS receiver) 151, CLK (clock oscillator) 152, ACT
(Address counter) 153, CGN (carrier frequency generator) 154, TMG (timing generator) 155, LP
F (low-pass filter) 156, TA (power amplifier) 157,
GAT (transmission gate circuit) 158, GAT (reception gate circuit) 159, LEV (reception level adjuster) 160, A
DC (analog-digital converter) 161, DSP (digital signal processor) 162, MPU (microprocessor) 163, D / O (digital output circuit) 164, R /
D (relay drive circuit) 165.

First, the clock signal from the GPS is ANT.
Received by the REC 151 by the 150, the REC 151
1pps (for sync signal and system reset), 10Mp
Output a clock of ps (for clock source) (S
1). The CLK 152 generates an arbitrary clock from 10 Mbps (S2), and the ACT 153 recognizes the address of each clock based on 1 pps (S3). CG
N154 generates a stepwise carrier wave synchronized with the clock generated in S2 (S4). At this time, it is possible to set the number of cycles to be sent according to the operation mode such as the constant mode, the inspection mode, and the accident mode. LPF
156 converts the stepwise carrier wave generated in S4 into a sine wave (S5). Next, TA157 amplifies the carrier wave converted into the sine wave in S5. GAT15
Reference numeral 8 controls the timing of signal transmission, and sends the carrier wave to the power line at the controlled timing of signal transmission (S
8). The TMG 155 controls the timing of transmission and reception synchronized with the partner station based on the input of the accident signal or the input of the inspection signal. Here, GAT158 (at the time of transmission:
S6) controls the timing of signal transmission based on TMG155, and GAT159 (at the time of reception: S7) is TMG.
The timing of signal reception is controlled based on 155. Further, the TMG 155 notifies the MPU 163 of information on the transmission signal and signal information received at the next reception timing from the partner station.

The GAT 159 receives the signal received from the partner station via the power line in S8 at the reception timing controlled by the TMG 155, and the LEV 160 adjusts the level of the received signal. The ADC 161 converts the received sine wave (analog signal) into a staircase waveform (digital signal), and the DSP 162 tests the converted staircase waveform. As will be described later, this test uses the time width, amplitude, and
It is performed by examining the slope, area, etc. MPU1
Reference numeral 63 processes the digital signals from the ADC 161 and the DSP 162, and also logs accident information, inspection information and the like. The D / O 164 outputs the digital signal processed by the MPU 163. Further, the R / D 165 outputs an accident signal to the circuit breaker operating relay circuit based on the output signal. Here, it goes without saying that each communication device may generate different carrier frequencies based on the clock signal from the GPS and continuously transmit and receive the generated carrier waves.

FIG. 5 is a diagram showing an example of the operating state of each unit of the communication device 15 shown in FIG. In this example, the processing operation of S1 to S8 in each unit of the communication device 15 illustrated in FIG. 4 will be described. First, in S1, REC1
51 is 1 pps (for synchronizing signal and system reset),
It outputs a clock of 10 Mbps (for original clock). This 1 pps clock contains information about the time. In S2, the CLK152 is the above S1.
An arbitrary carrier frequency generation clock is generated from the 10 Mbps generated in step 1, and the ACT 153 sets 1p in step S3.
The address of each clock is recognized with ps as a reference, and the stepwise carrier wave generated in the next S4 is controlled. In S4, the CGN 154 generates the stepwise carrier wave 21 synchronized with the clock generated in S2. At this time, it is possible to set the number of cycles according to the operation mode such as the constant mode, the inspection mode, the accident mode, or the like. In the case of signal transmission, in step S5, the LPF 156 converts the stepped carrier wave 21 generated in step S4 into a sine wave 22. Further, in the case of signal reception, in S8, the sine wave having the same frequency as the sine wave 22 is received by the GAT 159.

In addition, in S6 and S7, TMG15
Reference numeral 5 controls the timing of transmission and reception synchronized with the partner station based on the input of an accident signal or the input of an inspection signal. The GAT 158 (during transmission: S6) controls the signal transmission timing 23 based on the TMG 155, and
59 (during reception: S7) controls the signal reception timing 24 based on the TMG 155. The signal transmission / reception timing 25 in S8 is controlled based on the processing in S6 and S7. in this way,
According to the present invention, the timing of transmission / reception can be controlled in synchronization with the clock signal from GPS, so that even between a plurality of devices, it is possible to specify a signal from a partner station and perform communication alternately. And

FIG. 6 is a diagram showing an example of a transmission / processing timing chart of the communication device 15, in which S11 to S2 are shown.
0 is a job unit for processing, t1 to t11 are timing times, and A and B are electric stations. FIG. 6A shows a timing chart, and FIG. 6B shows one cycle of operation.

In the example of the timing chart shown in FIG. 6A, the job S11 transmitted from the electric station A at the timing t1 is received at the electric station B at the timing t2,
The job S11 is processed at the electric station B. Next, the job S12 transmitted from the electric station B at the timing t2 is received by the electric station A at the timing t3, and the job S12 is processed at the electric station A. In this way, signals can be mutually transmitted and received between the electric stations A and B at the same timing. Here, the transmission / reception timing time can be obtained by the following formula (1), and the actual transmission / reception timing time may be set to be equal to or longer than the timing time obtained from this formula (1). (In this example, the speed of the carrier wave is equal to the speed of light). Transmission path length / Carrier speed (Light speed: 3 × 10 ⁸ m / s) + Carrier transmission cycle number Equation (1) Note that the signal processing time should be within one cycle after receiving the signal. To

In the operation example of one cycle shown in FIG. 6B, 30 is the time (t0) of one cycle, and the time (t0) of the one cycle is the timing t shown in FIG. 6A.
The time from 2 to the timing t4 is shown. One cycle time (t0) is the transmission occupied time t (t: t0 / 2).
And the reception occupied time t (t: t0 / 2), the breakdown of which is: transmission time 31: τ of job S12, job S1
The total time 32: η of the reception processing time of 1 and the transmission processing time of the job S14 and the reception time 33: τ of the job S13 are summed. Where n is the number of transmission cycles,
f: carrier frequency (kHz), L: line length (m), transmission time 31 of job S12: τ, job S11
The total time 32: η of the reception processing time of the job and the transmission processing time of the job S14, and the reception time 33: τ of the job S13 can be obtained by the following expressions (2) to (4). Transmission time 31 of job S12: τ = n / f (Equation (2)) Reception time 33 of job S13: τ = n / f (Equation (3) Reception processing time of job S11 and transmission processing of job S14 Total time with time 32: η = (t−τ) × 2 ... Formula (4)

Here, the communication device 15 can set a plurality of different transmission cycle numbers for carrier waves having the same clock number, and can assign a code created in advance to each of the set transmission cycle numbers. As the code created in advance, for example, a constant code for monitoring the operation status of each electric station, an inspection code for checking the operation status of each electric station, an accident code sent when an accident occurs, etc. Is set according to the number of sending cycles. In this way, by setting the operation mode for each of the number of transmission cycles, it becomes possible to easily and efficiently operate the system.

The operation modes of the communication device 15 will be described. In the case of the constant mode, for example, the operation status of each unit is sequentially checked by synchronizing with the synchronization signal (1 sec), and if an abnormality occurs, logging is set. At this time, the master side monitors the operation statuses of the master side and the slave side, the slave side monitors the operation status of the slave side, and sends the investigation result of the operation status to the master side. In the inspection mode, start the inspection mode from the master side, start the inspection on the master side, and send the "inspection code" to the slave side.
On the slave side, after receiving the “check code” from the master side, the operation status check result is sent to the master side by the same operation as in the above-described constant mode. Further, in the accident mode, the accident mode is switched from the constant mode or the inspection mode to the accident mode by inputting accident information from the relay on the master side or the slave side, and the "accident code" is sent to the other side. The other party receives the sent "accident code" and receives the received "accident code".
After checking, output the trip command to the relay.

FIG. 7 is a diagram showing the relationship between the number of cycles and the line length. In this example, the carrier frequency is 250 kHz,
It shows the waveform characteristics of the carrier wave when the number of cycles is five. FIG. 7A shows a waveform when the line length is 1 km. In the figure, 40 is a waveform of a carrier wave (sine wave), 41.
Represents a carrier wave transmission timing control signal, and is shown in FIG.
7A is an enlarged waveform of the waveform shown in FIG. 7A. In the figure, 42 is a carrier wave waveform (sine wave), and 43 is a carrier wave transmission timing control signal. When transmitting the accident signal through the power line 20, the communication device 15 of the electric station A according to the present invention starts the phase angle of the accident signal cycle from 0 degree and ends at 360 degrees (1 cycle). Then, the accident signal whose phase angle is controlled is repeatedly transmitted to the communication device 15 of the electric station B. “N” in FIG. 7A indicates a predetermined number of cycles, and in this example, 5 cycles, so N = 5.
Becomes The communication device 15 of the electric station B receives the accident signal from the electric station A through the time filter set to the time width based on the same transmission / reception timing. in this way,
By controlling the phase, it is possible to minimize the spread of the frequency spectrum of the carrier wave, and it is possible to realize higher quality and higher speed signal transmission. here,
The control so as to start from 0 degree and end at 360 degrees can be similarly performed with each signal in the constant mode and the inspection mode.

Further, when transmitting a carrier wave having the same clock number through the power line 20, the communication device 10 sets one cycle or more of the clock number of the carrier wave as one symbol, and sets at least one set symbol. It can be transmitted as 1 bit.

FIG. 8 is a diagram showing an example of simulation of a sinusoidal sampling waveform. FIG. 8 (A) shows
FIG. 8 shows the waveform of the carrier wave when the carrier wave frequency is 250 kHz and the sampling frequency is 2500 kHz.
(B) shows a waveform when the carrier frequency is 250 kHz and the sampling frequency is 10000 kHz. According to the sampling theorem, the sampling frequency may be twice the signal frequency, but in order to faithfully reproduce the original signal, a sampling frequency of about 40 times is required. The same can be said when generating a smooth sine wave from a stepped waveform. That is, in order to generate a carrier wave whose phase is controlled from 0 degree to 360 degrees, a staircase waveform is created at a sampling frequency of several ten times to several tens of times the carrier frequency and passed through a low pass filter. This will be possible. Generally, the sampling frequency is the number of samplings performed in 1 second when converting an analog signal into a digital signal in Hz.
It is expressed in units of.

FIG. 9 is a flow chart for explaining an example of the protection relay method to which the present invention is applied. A case where an accident is detected at the electric station A will be described as the applicable range of the present system from step S22 to step S26 in this example. First, the direction of the current is detected by the CT 12 as a predetermined amount of electricity at the electric stations at both ends (step S21), and the Ry 14 determines whether or not there is an abnormal input based on the detected direction of the current (step S2).
2) If the result of the determination is that there is an abnormal input,
The communication device 15 receives the accident signal from the Ry 14 and sends the received accident signal to the electric station B via the power line 20 (step S23). Here, when the accident signal from the electric power station A is sent to the electric power station B,
The communication device 15 is synchronized with the electric power station A via the power line 20 by synchronizing the clock of the communication device 15 on the basis of the clock signal from the GPS and transmitting / receiving the accident signal at alternate timings and using the same number of clocks. It is possible to mutually perform between the places B. When it is determined in step S22 that there is no abnormal input (the current direction is normal), the process returns to step S21 and is repeated.

Next, the communication device 15 uses the above step S2.
The received signal from the electric station B corresponding to the accident signal sent in 3 is confirmed (step S24). After confirming the received signal from the electric station B, the communication device 15 receives the clock signal from the GPS and measures the clock based on the received clock signal (step S25). Next, the communication device 15 synchronizes the clock of the communication device 15 of the electric station B on the basis of the clocked time and outputs an accident signal to the relay side at the same timing (step S26), and further Ry14 of both electric stations. Outputs a trip command for disconnecting the electric power station A and the electric power station B from the power line 20 to each CB 11 based on the output accident signal,
According to this output signal, the CB 11 is opened to separate the faulty section from the system (step S27). Where CB11
The CBs 11 may not be necessarily opened at the same timing, and each CB 11 may be opened in the order of electric station A → electric station B or electric station B → electric station A. Further, when the clock signal is continuously or regularly received from the GPS to measure the time, the step S25 may be appropriately executed in any step.

FIG. 10 shows that the carrier frequency is 250 kHz.
FIG. 5 is a diagram showing an example of an accident-trip time characteristic when 0 cycles are transmitted and received twice. In the figure, 50 is a characteristic graph showing the relationship between the time required until the trip and the transmission distance.
Is a characteristic graph including standard fluctuation time as a reference, 51
Indicates a characteristic graph including the maximum fluctuation time, and 53 indicates a characteristic graph including the minimum fluctuation time. The vertical axis represents the time required to trip (μs), and the horizontal axis represents the transmission distance between electrical stations (k
m), and in this example, the time required to trip in each of the characteristic graphs 51, 52, and 53 when the transmission distance is 20 km is 584 (μs) and 448 (μ) in order.
s) and 342 (μs). Here, as a factor that determines the fluctuation time, the time for confirming the accident signal (μs) and the time for judging the code (μs)
Therefore, the required time is calculated by adding these variable times to a fixed time such as code transmission time.

FIG. 11 is a diagram showing an example of the waveform test. The communication device 15 receives a carrier wave having the same number of clocks, detects at least one or more of the time width, the amplitude, the gradient, and the area in one cycle of the received carrier wave, and determines whether the carrier wave is the carrier wave. Can be matched. This allows the carrier wave to be detected without using a bandpass filter. In the sampling waveform shown in FIG. 11, the vertical axis represents the threshold level (| sin θ
|), The horizontal axis is the sampling number. For each of the above items of time width, amplitude, gradient, and area, it is verified whether the following conditions are satisfied, and if the conditions are satisfied as a result of the verification, the carrier is determined.・ Time width test (1) When | sin θ | = L ₁ Ti1 = Ti2, ti1 + Ti1 = ti2 + Ti2, t
i1 + Ti1 + ti2 + Ti2 = 1 / f ₀ (carrier frequency) (2) In the case of | sin θ | = L ₂ , Th1 = Th2, th1 + Th1 = th2 + Th2, t
h1 + Th1 + th2 + Th2 = 1 / f ₀ (frequency of carrier wave) ・ Amplitude test tp1 = tp2, V ₁ = V ₂・ Slope test (1) | sin θ | = L ₁ Sampling number 0-1, 5-6, 10-11 , 15-1
When 6, gradient = 0, sampling number 1-5, 11-1
5, the gradient> 0, the number of samplings 6-10, 16-
When 20, the gradient <0 (2) | sin θ | = L ₂ Sampling number 0-2,5-6,9-12,15-1
When 6, 19-20, gradient = 0, sampling number 2−
When 5, 12-15, gradient> 0, sampling number 6-
When 9, 16-19, slope <0-area test S ₁ = S ₂

[0040]

According to the present invention, the clock signals from the GPS are used to synchronize the communication devices at each electric station, and the transmission and reception are performed at alternating timings and with the same number of clocks between the electric stations. By superimposing the accident signal on the power line without modulating it, it is possible to perform communication without being restricted by the frequency band, and it is possible to perform high-speed communication even on a transmission line having a narrow frequency band such as the power line.

By utilizing the clock signal from GPS to synchronize the communication devices at each electric station and to adjust the transmission / reception timing, it is possible to mutually communicate between the plural electric stations.

Further, since three or more electric stations can communicate with each other, the number of communication devices installed can be reduced to one branch, and synchronization can be achieved by the clock signal from the GPS. With, it is not necessary to specify the destination by the station address or the header.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an outline of a protection relay system based on a current direction comparison method.

FIG. 2 is a block diagram illustrating a configuration of a protection relay system using a current direction comparison method according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a schematic structure of a communication device to which the present invention is applied.

FIG. 4 is a block diagram for explaining an internal configuration example of the communication device shown in FIG.

5 is a diagram showing an example of an operation state of each unit of the communication device shown in FIG.

FIG. 6 is a diagram showing an example of a timing chart of transmission / processing of the communication device.

FIG. 7 is a diagram showing the relationship between the number of cycles and the line length.

FIG. 8 is a diagram showing an example of simulation of a sine wave sampling waveform.

FIG. 9 is a flowchart illustrating an example of a protection relay method to which the present invention is applied.

FIG. 10 is a diagram showing an example of an accident-trip time characteristic when a carrier frequency is 250 kHz and 10 cycles are transmitted and received twice.

FIG. 11 is a diagram showing an example of a waveform test.

[Explanation of symbols]

10 ... Protective relay system, 11 ... CB, 12 ... CT, 1
3 ... CC, 14 ... Ry, 15 ... communication device, 150 ... AN
T, 151 ... REC, 152 ... CLK, 153 ... AC
T, 154 ... CGN, 155 ... TMG, 156 ... LP
F, 157 ... TA, 158 ... GAT (during transmission), 159
… GAT (when receiving), 160… LEV, 161… AD
C, 162 ... DSP, 163 ... MPU, 164 ... D /
O, 165 ... R / D, 15a ... Receiving section, 15b ... A /
D, 15c ... DSP, 15d ... PIO, 15e ... MP
U, 15f ... Transmitter, 15g ... GPS receiver, 15h ...
Power source, 16 ... BC, 17 ... CF, 20 ... Power line, 21 ...
Stepwise carrier wave, 22 ... Sine wave, 23 ... Signal transmission timing, 24 ... Signal reception timing, 25 ... Transmission / reception timing, 30 ... 1 cycle time (t0), 31 ... Job S12 transmission time, 32 ... Job The total time of the reception processing time of S11 and the transmission processing time of the job S14, 33 ...
Received time of job S13, 40, 42 ... Waveform of carrier wave,
41, 43 ... Carrier wave transmission timing control signal, 50 ...
Characteristic graphs 51, 52, 53 ... Characteristic graphs showing the relationship between the time required to trip and the transmission distance.

Continued front page    (72) Inventor Mitsuyuki Ota             Tsukenden, 9-3 Myeong-dori, Izumi-ku, Sendai-shi, Miyagi Prefecture             Ki Industry Co., Ltd. F term (reference) 5G047 AA01 AB06 BB01 CA03 CA05                       CA07

Claims (11)

[Claims] 1. A protective relay system for each electric station in an electric power system for transmitting and receiving electric power between two or more electric stations via a power line, wherein each protective relay system is predetermined in the electric station. Detection means for detecting the amount of electricity that has been detected, determination means for determining whether or not an accident has occurred in the power line between the electric power stations based on the amount of electricity detected by the detection means, and the result determined by the determination means , When it is determined that an accident has occurred, a trip signal for shutting off the electric power station from the electric power line and a notification to the adjacent electric power station that the electric power line between the electric power stations has an accident A protective relay that outputs an accident signal, a breaker that shuts off the electric power station from the power line based on a trip signal from the protective relay, and a G for receiving a clock signal from GPS. A PS receiver, a timekeeping means for timekeeping based on a clock signal received from the GPS by the GPS receiver, and an accident signal from the protective relay based on the clock timed by the timekeeping means via the power line. At least a communication device for transmitting and receiving between adjacent electric stations, the clocks of the communication devices of the adjacent electric stations are synchronized by the clocking means to transmit and receive at alternate timings, and the same number of clocks is used. The protection relay system is characterized in that the accident signal can be mutually transmitted and received between the two or more electric stations via the power line. 2. The protection relay system according to claim 1, wherein at least an electric current is detected as the predetermined amount of electricity, and an accident is judged based on a direction of the detected electric current. Relay system. 3. The protective relay system according to claim 1, wherein the alternate timing of transmission and reception is transmission of a superimposed wave (carrier wave) having a transmission path length between the electric stations and the same number of clocks. A protective relay system, which is set for a time longer than that determined based on the number of cycles. 4. The protective relay system according to claim 1, wherein the communication device, when transmitting the accident signal through the power line, has a phase of a carrier frequency of the accident signal. The angle is controlled from the 0 degree to the 360 degree (1 cycle) and is repeatedly controlled according to the predetermined number of transmission cycles, and the accident signal with the controlled phase angle is transmitted to the communication device of the adjacent electric station. The protection relay system, wherein the communication device of the adjacent electric station receives the accident signal via a time filter set to a time width based on the alternate timing of the transmission and reception. 5. The protective relay system according to claim 1, wherein the communication device has a plurality of different transmission cycle numbers for the superimposed waves (carrier waves) having the same clock number. Set, and has a code assigning means for assigning a code created in advance to each of the set number of sending cycles, the clocking means synchronizes the clocks of the communication devices of the adjacent electric stations to transmit and receive at alternating timings, Further, the protection relay system is characterized in that the codes assigned by the code assigning means can be mutually transmitted and received between the two or more electric stations through the power line using the same number of clocks. 6. The protective relay system according to claim 5, wherein the pre-created code is at least a constant code for monitoring the operating status of each electric station, and the operating status of each electric station is checked. A protective relay system that includes an inspection code for performing the accident and an accident code sent when an accident occurs. 7. The protective relay system according to claim 1, wherein the communication device receives a superposed wave (carrier wave) having the same number of clocks, and the received superposed wave (carrier wave). A protective relay system characterized by detecting at least one or more of time width, amplitude, gradient, and area in one cycle of a carrier wave. 8. The protective relay system according to claim 1, wherein the communication device enables transmission / reception of signals among three or more electric stations. Electric system. 9. The protective relay system according to claim 1, wherein the communication device transmits the superimposed wave (carrier wave) having the same number of clocks through the power line. A protection relay system, wherein one cycle or more of the number of clocks of the superimposed wave (carrier wave) is set as one symbol, and the set one symbol is transmitted as at least one bit. 10. A communication device in the protective relay system according to claim 1. 11. A protective relay method for each electric station in an electric power system for transmitting and receiving electric power between two or more electric stations via a power line, wherein a predetermined amount of electricity at the electric station is detected. And a determination step for determining whether or not an accident has occurred in the power line between the electric stations based on the detected amount of electricity, and as a result of the determination, when it is determined that an accident has occurred, An accident signal output step of outputting an accident signal for notifying an adjacent electric station that an accident has occurred on the power line between the electric stations, and receiving from the adjacent electric station according to the output accident signal. A received signal confirmation step of confirming a signal, a clock signal reception step of receiving a clock signal from GPS,
A clocking step for performing timekeeping based on a clock signal received from the GPS; a transfer step for transferring the accident signal to the relay side at the same timing as the adjacent electric station based on the clocked clock; A trip signal transmitting step for transmitting a trip signal for disconnecting the electric station and the adjacent electric station from the power line based on an accident signal, and the adjacent electric station in the accident signal outputting step. The clock of the communication device is synchronized based on the clock signal from the GPS, transmission and reception are performed at alternate timings, and the same number of clocks is used to send the accident signal through the power line to the two or more electric stations. A protective relay method characterized by enabling mutual transmission / reception.