JP2017229197A - Synchronization tester and automatic synchronous input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy of a phase difference based on charge current through a power cable on a synchronous input condition by eliminating difficulty in laying a signal cable or danger in removing an instrument transformer in a hot-line state and by eliminating the need for an instrument transformer on the power generator side or on the power distribution line side in conventional synchronization testers or automatic synchronous input devices when a synchronous power generator is temporarily installed.SOLUTION: In detecting a phase difference of a synchronous input condition in performing system paralleling on a power system and a synchronous power generator, the synchronous condition including a voltage difference, a frequency difference, and the phase difference, a phase on the synchronous power generator side is detected on the basis of a fundamental wave component of ground charge current on the synchronous power generator side. Utilization of the ground charge current on the synchronous power generator side eliminates the conventional need for an instrument transformer on the synchronous power generator side and improves detection accuracy of a phase difference based on charge current through a power cable.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a synchronous tester and an automatic synchronous input device used for a circuit breaker operation when a synchronous generator is connected to a grid.

  When the synchronous generator is connected to the power grid, the required allowable voltage difference, allowable frequency difference, and phase difference must be small in order to reduce the inrush current at the time of synchronous switching between the synchronous generator and the grid. Is required.

  When connecting a synchronous generator to the power system, both the generator and the system are provided with an instrument transformer or a capacitor-type voltage divider, and each output is input to a synchronous device such as a synchronous tester or an automatic synchronous input device. Judgment of the synchronization state between the generator and the system, and synchronous input for connecting the generator to the system are performed. Synchronous input is performed by closing the parallel switch with the voltage difference, frequency difference, and phase difference within the allowable range between the generator and the system.

FIG. 6 is a block diagram for explaining a configuration of an automatic synchronous charging apparatus when a generator is temporarily installed.
The bus 102 on the system side and the distribution line 103 are connected via a switch 105A, and the generator 107 and the distribution line 103 are connected via a switch 105B. An instrument transformer 106 A is already installed on the bus 102, and an instrument transformer 106 B is temporarily connected to the distribution line 103. The generator 107 is connected to the distribution line 103 via the circuit breaker 104B and the switch 105B.

  The automatic synchronizer 101 determines a voltage difference, a frequency difference, and a phase difference between the bus 102 side and the distribution line 103 side that is the generator side, and determines a state in which these differences are within an allowable range. The circuit breaker 104 </ b> A provided between the bus 102 and the switch 105 </ b> A is closed, and the bus 102 is connected to the distribution line 103 to perform synchronization. The switch has a specification for opening and closing a normal load current, and the circuit breaker has a specification for safely opening and closing even a large current such as a short circuit current in addition to the function of the switch.

The automatic synchronizer 101 obtains voltage, frequency, and phase information on the bus 102 side by connecting the secondary side of the instrument transformer 106A.
On the other hand, the automatic synchronous input device 101 connects the secondary side of the instrument transformer 106C installed on the distribution line side from the generator 107, or connects the secondary side of the temporary instrument transformer 106B. By doing so, the voltage, frequency, and phase information on the generator 107 side or the distribution line 103 side is input. In FIG. 6, connection of the instrument transformer 106 </ b> C is performed by the signal cable A, and connection of the temporary instrument transformer 106 </ b> B is performed by the signal cable B. For comparison with the bus side, either the signal cable A or the signal cable B can be used.

The automatic synchronizer 101 includes a synchronizer 111 and a synchronizer 112. The synchronous tester 111 is connected to the secondary side of the instrument transformer 106A and the secondary side of the temporary instrument transformer 106B or the instrument transformer 106C. The synchronous tester 111 detects a voltage difference, a frequency difference, and a phase difference between the bus side and the generator side or the distribution line side, and sets the synchronization input condition based on whether these differences are within an allowable range. judge. The synchronization input circuit 112 opens and closes the circuit breaker 104A based on the determination result of the synchronization tester 111 (for example, Patent Document 1).

  In FIG. 6, when power is being transmitted to the distribution line 103 by the temporary generator 107 in the event of an accident or work at a substation or the like, at the time of recovery, when the supply by the temporary generator is stopped and the supply from the bus is resumed, In order to carry out power supply to the distribution line without stopping, the circuit breaker 104 </ b> A is closed and the distribution line 103 is synchronously inserted into the system, and then the temporary generator 107 is disconnected from the distribution line 103.

  In phase discrimination for phase comparison between distribution lines, when performing phase discrimination after replacement of receiving lines (cables, overhead lines), transformers, and bus connection cables in distribution systems, etc. For the purpose of reducing labor and time, and reducing the danger due to the direct connection of the phase detector to the high voltage circuit, the phase of the line to be compared for phase discrimination is detected based on the charging current of the power cable, It has been proposed to perform phase discrimination by comparing the phase with the phase of the reference side line (Patent Document 2).

Japanese Patent Publication No. 5-84130 No. 6-40115

  In FIG. 6, when the power state of the temporary generator 107 is input to the synchronous tester 111 using the secondary signal cable A of the instrument transformer 106C installed on the distribution line side of the generator. Depending on the location and environment of the generator, it may be difficult to lay the signal cable A.

  In FIG. 6, in the configuration in which the power state of the distribution line is input to the synchronous tester 111 using the secondary signal cable B of the temporary instrument transformer 106B, the temporary instrument transformer 106B is connected to the circuit breaker 104A. Since it is necessary to install on the distribution line side, after the circuit breaker 104A is closed and turned on to recover, the temporary instrument transformer 106B is removed in a live state, which is dangerous.

  The above-mentioned difficulty in laying signal cables and the risk of removing the instrument transformer in a live state are detected using the instrument transformer to detect the power state on the generator side or distribution line side. It is due to that.

  For this reason, conventional synchronous testers and automatic synchronous insertion devices have problems in the difficulty of laying signal cables and the risk of removing instrument transformers in a live state, and there is a need to solve this problem. Yes.

  By applying the phase discrimination technique of phase discrimination described in Patent Document 2 in the conventional synchronous tester and automatic synchronous input device, and using the charging current of the power cable instead of the voltage by the instrument transformer, There is a problem that the accuracy of the phase difference that can be detected is insufficient to perform automatic synchronization. The phase discrimination disclosed in Patent Document 2 is not a technique for merely determining the phase relationship between the comparison-side line and the reference-side line and determining the phase difference.

  When operating a synchronous generator in a grid-connected operation, the phase verification between the generator side and the system side is required to be within an allowable range as a synchronous closing condition for synchronous verification and automatic synchronous closing when the circuit breaker is turned on. On the other hand, the phase discrimination is mainly intended to determine the phase relationship between the comparison-side line and the reference-side line, and thus high accuracy is not required for the phase difference.

  Therefore, in the synchronous verification and automatic synchronous charging when the synchronous generator is connected to the grid, the technology of phase discrimination based on the charging current of the cable of Patent Document 2 is simply applied to the conventional synchronous verification device and automatic synchronous charging device. It is not possible to obtain the synchronous input condition with the required accuracy only by doing.

  In order to perform the synchronization verification, it is necessary to minimize the influence of the waveform distortion of the measurement signal. In particular, the charging current of the power cable has a characteristic that it is greatly distorted by harmonic components. In the phase comparison method in which the positive part of the charging current waveform is a rectangular wave, the zero point of the rectangular waveform moves when the distortion due to the harmonic component is large, making it difficult to identify the synchronization point. May become a factor of input in a state out of synchronization.

  Therefore, the present invention solves the above-mentioned conventional problems, and eliminates the difficulty of laying signal cables in the conventional synchronous tester and automatic synchronous feeder, and the risk of removing the instrument transformer in a live line state. The purpose is to eliminate the need for an instrument transformer on the generator side or distribution line side.

  It is another object of the present invention to improve accuracy in detecting a phase difference based on a charging current of a power cable under a synchronous input condition.

  The synchronous tester and the automatic synchronous input device of the present invention are synchronized in the detection of the phase difference among the voltage difference, the frequency difference, and the phase difference, which are the synchronous input conditions when the power system and the synchronous generator are paralleled. The synchronous generator side phase detector detects the phase on the synchronous generator side based on the fundamental wave component of the ground charging current on the generator side. No transformer is required. This eliminates the difficulty of laying the signal cable and the risk of removing the instrument transformer in a live state. Further, based on the fundamental wave component of the ground charging current, errors due to high frequency components included in the charging current can be eliminated, and the phase difference detection accuracy can be improved.

(Synchronous tester)
The synchronous detector of the present invention is a synchronous tester for verifying the synchronous state of the power system and the synchronous generator in parallel with the system,
(A) Phase detection means for detecting a wiring phase signal corresponding to the phase of the wiring voltage of the distribution line connected to the synchronous generator based on the fundamental wave component of the ground charging current on the synchronous generator side. (B) The wiring phase signal. And phase difference detection means for detecting a phase difference between the phase of the system voltage and the phase of the wiring voltage based on the system phase signal of the system voltage on the system side and (c) a synchronization point for calculating a synchronization point based on the phase difference And an arithmetic means.

  The phase detection means, the phase difference detection means, and the synchronization point calculation means can be realized by software processing by computer calculation processing or by hardware circuit configuration. , A CPU, and an arithmetic circuit including a memory or the like provided with a program for causing the CPU to perform signal processing. The circuit configuration by hardware may be a dedicated circuit such as a DSP.

  The phase detection means uses the fundamental wave component of the ground charging current on the synchronous generator side as an input signal in the detection of the wiring phase signal corresponding to the phase of the wiring voltage of the distribution line connected to the synchronous generator. Based on the fundamental wave component, it is possible to eliminate a noise signal due to a high frequency component contained in the ground charging current.

  The phase detection means includes fundamental wave extraction means for extracting a fundamental wave component of the ground charging current. The fundamental wave extracting means can extract the frequency component in the frequency region of the system voltage from the frequency component of the ground charging current by each aspect of digital signal processing and analog signal processing. The fundamental wave component of the ground charging current is a frequency component in the frequency region of the system voltage, and can be the same frequency component as the fundamental wave of the power system in parallel with the system.

  In the present invention, phase comparison is performed with the fundamental wave component extracted from the signal of the ground charging current, so that it is possible to detect the phase error within several degrees even for a current waveform including harmonics.

-Aspect by digital signal processing:
The fundamental wave extraction means by digital signal processing extracts the fundamental wave component of the ground charging current from the discrete sampling value obtained by sampling the ground charging current by discrete Fourier transform or low-pass filter processing by a digital filter.

・ Analog signal processing mode:
The fundamental wave extraction means by analog signal processing extracts the fundamental wave component of the ground charging current by subjecting the ground charging current to low-pass filtering using an analog filter.

  As the ground charging current, the current flowing in the grounding conductor of the distribution line can be used. More specifically, the current flowing in the grounding conductor for the metal sheath connected to the power cable for drawing the distribution line provided in the distribution line is used. The ground charging current flowing through the metal sheath grounding conductor can be detected by providing a current measuring current transformer in the metal sheath grounding conductor.

(Automatic synchronization device)
The automatic synchronizer of the present invention is an automatic synchronizer in which a synchronous generator is system-paralleled to a power system, and the synchronous point calculated by the synchronous tester of the present invention and the synchronous point calculation means provided in the synchronous tester of the present invention. And a synchronous input circuit for outputting a synchronous input command signal for causing the synchronous generator to be system-parallel to the electric power system.

  As described above, the synchronous tester and the automatic synchronizer of the present invention are difficult to lay the signal cable in the conventional synchronizer and automatic synchronizer and the removal of the instrument transformer in the live state. This eliminates the danger of power generation and eliminates the need for an instrument transformer on the generator side or distribution line side.

  Moreover, the synchronous tester and the automatic synchronous input device of the present invention can improve the accuracy in detecting the phase difference based on the charging current of the power cable under the synchronous input condition.

It is a block diagram for demonstrating schematic structure of the synchronous tester and automatic synchronous injection | throwing-in apparatus of this invention. It is a block diagram for demonstrating the example of a structure of the synchronous tester and automatic synchronous injection | throwing-in apparatus of this invention. It is a block diagram for demonstrating the function of the arithmetic processing part of this invention. It is a figure for demonstrating the signal example of the synchronous tester of this invention, and an automatic synchronous injection | throwing-in apparatus. It is a block diagram for demonstrating the other structural example of the synchronous tester and automatic synchronous injection | throwing-in apparatus of this invention. It is a block diagram for demonstrating one structure of the automatic synchronous injection | throwing-in apparatus in the time of the conventional generator temporary installation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, the schematic configuration of the synchronous tester and the automatic synchronous input device of the present invention will be described with reference to FIG. 1, and the configuration example of the synchronous tester and the automatic synchronous input device of the present invention will be described with reference to FIG. Is used to explain the function of the arithmetic processing unit of the present invention, FIG. 4 is used to explain an example of the signal of the synchronous tester and the automatic synchronization input device of the present invention, and FIG. Another configuration example of the automatic synchronization input device will be described.

[Schematic configuration of synchronous tester and automatic synchronous input device]
FIG. 1 is a block diagram for explaining a configuration of a synchronous tester and an automatic synchronous input device of the present invention.

  The bus 2 on the system side and the distribution line 3 are connected via a circuit breaker 4A and a switch 5A, and the synchronous generator 50 and the distribution line 3 are connected via a circuit breaker 4B and a switch 5B. ing. Voltage acquisition means 9 is already installed in the bus 2, and power distribution cables 6A, 6B, 6C are provided in the distribution line 3 for each of the R phase, S phase, and T phase. The power cables 6A, 6B, and 6C are connected to the metal sheath grounding conductors 7A, 7B, and 7C of the distribution line drawing power cable for each phase. Each metal sheath grounding conductor 7A, 7B, 7C is provided with grounding current measuring current transformers 8A, 8B, 8C, and each grounding current measuring current transformer 8A, 8B, 8C is for grounding each metal sheath. The ground charging current flowing through the conductors 7A, 7B, 7C is measured.

  The frequency and phase of the ground charging current of each phase correspond to the frequency and phase of the voltage of each phase of the distribution line 3. The synchronous tester of the present invention uses the fact that the frequency and phase are in a correspondence relationship between the ground charging current and the distribution line voltage, and measures the ground charging current instead of measuring the distribution line voltage. By doing so, the frequency and phase of the distribution line are detected. The synchronous generator 50 is connected to the distribution line 3 through the circuit breaker 4B and the switch 5B.

  As in the configuration shown in FIG. 6, the automatic synchronous input device 20 determines a voltage difference, a frequency difference, and a phase difference between the bus side and the distribution line 3 side that is the synchronous generator side, and these differences. Is determined to be within the allowable range, and the circuit breaker 4A provided between the bus 2 and the switch 5A is closed, and the bus 2 is connected to the distribution line 3 to perform synchronization. The switch has a specification for opening and closing a normal load current, and the circuit breaker has a specification for safely opening and closing even a large current such as a short circuit current in addition to the function of the switch.

  The automatic synchronization input device 20 acquires the voltage, frequency, and phase information on the bus 2 side by connecting the secondary side of the voltage transformer of the voltage acquisition means 9. On the other hand, the automatic synchronous input device 20 inputs the frequency and phase information on the side of the synchronous generator 50 or the distribution line 3 by inputting the ground charging current of the distribution line 3. In addition to measuring the bus voltage using a voltage transformer or a capacitor-type voltage divider, the voltage acquisition means 9 may measure the line voltage between the phases using a voltmeter.

  The automatic synchronization input device 20 includes a synchronization tester 1 and a synchronization input circuit 21. The synchronous tester 1 is connected to the secondary voltage of the instrument transformer of the voltage acquisition means 9 and the secondary side of the ground charging current measuring current transformers 8A, 8B, 8C. Further, voltage information on the side of the synchronous generator 50 or the distribution line 3 is input. The voltage information from the synchronous generator 50 can be transmitted by communication means (not shown). The synchronization tester 1 detects a voltage difference, a frequency difference, and a phase difference between the bus side and the synchronous generator side or the distribution line side, and based on whether these differences are within an allowable range, Determine. The synchronization input circuit 21 closes the circuit breaker 4A based on the determination result of the synchronization tester 1.

  The synchronous tester 1 detects a wiring phase signal corresponding to the phase of the wiring voltage of the distribution line 3 connected to the synchronous generator 50 based on the fundamental wave component of the ground charging current of the power cable on the synchronous generator 50 side. Phase detection means 1A, phase difference detection means 1B for detecting the phase difference between the phase of the system voltage and the phase of the wiring voltage based on the wiring phase signal and the system phase signal of the system voltage on the system side, and phase difference detection Synchronization point calculation means 1C for calculating a synchronization point based on the phase difference detected by the means 1B.

  The fundamental wave component of the ground charge current can be extracted by the fundamental wave extracting means 1E. The fundamental wave extracting means 1E may be provided outside the synchronization tester 1 in addition to the configuration provided inside the synchronization tester 1.

  The synchronization verification means 1D uses the synchronization point information calculated by the synchronization point calculation means 1C, along with the phase difference between the system side and the synchronous generator side, and the frequency on the synchronous generator 50 side or the distribution line 3 side and the system side system. Based on the frequency difference from the frequency and the voltage difference between the voltage of the synchronous generator 50 and the system voltage on the system side, the synchronization application condition is determined.

  The synchronization tester 1 outputs a synchronization verification signal to the synchronization input circuit 21 when the synchronization verification unit 1D determines the synchronization input condition. When receiving the synchronization verification signal, the synchronization input circuit 21 outputs a synchronization input command to the relay 10. The relay 10 closes the circuit breaker 4 </ b> A when receiving the synchronous input command.

[Configuration example of synchronous tester and automatic synchronous injection device]
A configuration example of the synchronization tester and the automatic synchronization input device, and a calculation process performed by the synchronization tester will be described with reference to FIGS.

  The configuration example of the synchronous tester and the automatic synchronization input device shown in FIG. 2 is the same as the configuration example of the synchronous verification device 1 and the synchronous generator in the schematic configuration diagram shown in FIG. An example is shown.

  In FIG. 2, the synchronous tester 1 inputs the ground voltage Vrn or the line voltage Vl of the bus line obtained by the voltage obtaining means 9 of the voltage transformer 9a or the non-grounded transformer 9b as the system voltage information, and the distribution line The ground charging current acquired by the current transformers 8A to 8C provided in the grounding conductors 7A to 7C of 3 is input, and the voltage signal Vg is input from the synchronous generator 50.

  In the voltage acquisition means 9, the ground voltage of the bus is measured using a grounded-type instrument transformer or a capacitor-type voltage divider as the instrument transformer 9 a, and the line voltage between the phases is measured by the non-grounded transformer 9 b. May be.

(Configuration of synchronous tester)
The synchronization tester 1 includes level conversion circuits 11A to 11D for adjusting the amplitude of an input signal.

  The level conversion circuit 11A receives the voltage information of the bus 2 obtained from the voltage acquisition means 9 as an input signal, and converts the signal level to a predetermined level. When using a grounded-type instrument transformer (EVT) or a capacitor-type voltage divider (PD) as the instrument transformer 9a, the neutral point is grounded using the primary and secondary sides as star connections, The voltage between the sex points (phase voltage) is measured, and the line voltage Vl is measured by using a non-grounded instrument transformer (VT) as the non-grounded transformer 9b.

  The voltage acquired by the voltage acquisition means 9 has a signal level difference of √3 times and a phase difference of (π / 6) between the phase voltage and the line voltage. The level conversion circuit 11A converts the signal level acquired by the voltage acquisition unit 9 in order to make it easy to handle the signal processing in the subsequent stage multiplexer.

  The level conversion circuits 11B, 11C, and 11D input the ground charging currents of the grounding conductors 7A to 7C acquired by the current transformers 8A to 8C as input signals, and convert the signal level to a predetermined level. The ground charging current is used to determine the synchronization condition of the frequency difference and phase difference between the bus side and the synchronous generator side, and the soundness of the power cable based on the phase shift in each phase on the bus side and the synchronous generator side Used to determine The level conversion circuits 11B, 11C, and 11D can improve the accuracy of the above-described synchronization condition and soundness determination by matching the signal level of each ground charging current.

  In FIG. 2, the signal level of the R-phase ground charging current Ir is converted by the level conversion circuit 11B and used to determine the synchronization condition of the frequency difference and the phase difference, and the S-phase and T-phase are converted by the level conversion circuits 11C and 11D. Although the example which converts the signal level of ground charging current Is and It and uses it for the judgment of soundness is shown, the combination of the ground charging current used for judgment of a synchronous condition and soundness is not restricted to this combination .

  The synchronous tester 1 includes a multiplexer 12 for sequentially processing input signals from the level conversion circuits 11A to 11D by the arithmetic processing unit 13. The multiplexer 12 sequentially inputs the input signals input from the level conversion circuits 11 </ b> A to 11 </ b> D to the arithmetic processing unit 13. The order of input to the arithmetic processing unit 13 can be arbitrarily set.

(Function of the processing unit)
The arithmetic processing unit 13 inputs the bus side voltage (Vrn, Vl), the synchronous generator side voltage signal Vg and the ground charging currents Ir, Is, It, and the voltage difference between the bus side and the synchronous generator side. In addition to determining the synchronization condition based on the frequency difference and the phase difference, a control signal for controlling the voltage and frequency of the synchronous generator is used. Further, the soundness of each phase current is determined based on the ground charging current flowing through the power cable. The voltage signal Vg on the synchronous generator side can be input by communication means.

  The arithmetic processing unit 13 includes an A / D converter 13a that converts an output signal of the multiplexer 12 into a digital signal, a CPU 13b that performs arithmetic processing, a ROM 13c that stores a program for causing the CPU 13b to execute predetermined processing, and a result of the arithmetic processing Is connected to a bus 13e.

  FIG. 3 is a block diagram for explaining the outline of the arithmetic processing by the arithmetic processing unit 13. The synchronization verification means 13L tests the synchronization conditions of the voltage difference, the frequency difference, and the phase difference for the synchronization state of the power system and the synchronous generator in parallel, detects the synchronization point, and outputs the synchronization point signal. The verification of the synchronization condition is performed using the fundamental wave extracted from the bus voltage V by the fundamental wave extraction means 13Dv.

  The voltage difference synchronization condition is determined by comparing the bus voltage V detected by the voltage detection means 13A and the voltage signal Vg of the synchronous generator by the voltage comparison means 13H, and whether or not the voltage difference is within a predetermined allowable value. Test by

  The frequency difference synchronization condition is as follows: the frequency of the bus side voltage detected by the frequency detector 13B and the frequency of the fundamental wave of the ground charging current Ir detected by the frequency detector 13E are compared by the frequency comparator 13I. The test is performed based on whether or not the value is within a predetermined allowable value. The fundamental wave of the ground charging current Ir can be extracted from the ground charging current Ir by the fundamental wave extracting means 13Dr.

  The fundamental wave extraction unit 13Dr extracts a fundamental wave by an arithmetic process that performs discrete Fourier transform on the sampling value of the ground charging current. The frequency detector 13E detects the frequency on the synchronous generator side based on the fundamental wave extracted by the fundamental wave extractor 13Dr. FIG. 3 shows an example in which the R-phase ground charging current Ir is used as the ground charging current used for the synchronization verification, but the fundamental wave is extracted using the S-phase or T-phase ground charging currents Is and It. May be.

  The synchronization condition of the phase difference is that the phase of the synchronous generator side obtained from the phase of the bus side voltage detected by the phase detection means 13C and the fundamental wave of the ground charging current Ir detected by the phase detection means 13F and the phase shift means 13G. The phase on the distribution line side is compared by the phase difference comparison means 13J, and it is verified whether the phase difference is within a predetermined allowable value. The phase shift means 13G performs a process of delaying the phase obtained from the ground charging current Ir by (π / 2). This is because the phase of the ground charging current Ir is a current due to the ground capacitance of the power cable, and therefore is (π / 2) ahead of the voltage of the R phase of the distribution line 3, so the phase obtained from the ground charging current Ir Is delayed by (π / 2) so as to be in phase with the phase of the R-phase voltage on the distribution line side, which is the phase on the distribution line side.

  The synchronization verification unit 13L receives the voltage difference from the voltage comparison unit 13H, the frequency difference from the frequency comparison unit 13I, and the phase difference from the phase difference comparison unit 13J, and determines the synchronization condition. When the synchronization condition is determined, a synchronization point signal is output to the synchronization input circuit 21. The synchronous closing circuit 21 is operated by sending a synchronous closing command signal to the relay 10, closes the circuit breaker 4A, and synchronously inputs the distribution line connected to the synchronous generator to the bus.

(Automatic synchronization device)
The automatic synchronizer 20 includes a synchronizer 1 and a synchronizer 21 that receives a synchronization point signal from the synchronizer 1 and outputs a synchronizer command signal to the relay 10. The relay 10 operates in response to the synchronous input command signal, closes the circuit breaker 4A, and synchronously supplies the distribution line connected to the synchronous generator to the bus.

(Health assessment)
In order to determine the soundness of the power cable on the distribution line side, it is detected whether the phases between the phases of the ground charging currents Ir, Is, It are in a predetermined relationship. For example, when the bus voltage is input as the phase voltage, the phase difference between the R phase voltage and the R phase ground charging current Ir after the phase shift to the (π / 2) delay side is within a range of ± Δθ. Yes, the phase difference between the R phase voltage of the bus voltage and the ground charging current Is of the S phase after the phase shift is in the range of (2π / 3) ± Δθ, and the R phase voltage of the bus voltage and the T phase after the phase shift. The phase difference of the ground charging current It of the phase is in the range of (4π / 3) ± Δθ, and the difference of the ground charging currents Ir, Is, It of each phase is within a predetermined range (for example, 10%). Can do. When the bus voltage is input as a line voltage, the phase difference may be calculated by adding (π / 6).

  In order to confirm the soundness, the ground charging current Is is provided with a fundamental wave extracting means 13Ds, a phase detecting means 13Fs, and a phase shifting means 13Gs, and the ground charging current It is provided with a fundamental wave extracting means 13Dt, a phase detecting means 13Ft, and a phase shifting means 13Ft. Phase means 13Gt is provided.

  Further, the soundness judgment means 13K compares the phase of the ground charging currents Ir, Is, and It after the phase shift for each phase with the phase of the system phase signal obtained by the phase detection means 13C to obtain a phase difference, It is determined whether or not the phase difference is within a predetermined allowable range.

(Synchronous generator control)
The arithmetic processing unit 13 outputs a voltage control means 13M for outputting a voltage control signal for controlling the voltage of the synchronous generator, and a frequency control signal for controlling the frequency of the synchronous generator, in addition to the signal processing related to the synchronous test described above. Frequency control means 13N for controlling the voltage and frequency of the synchronous generator. Delivery of signals to and from the synchronous generator can be performed by wireless communication.

  Further, a display control means 13O can be provided, and a display signal is output based on the outputs of the voltage comparison means 13H, the frequency comparison means 13I, and the phase difference comparison means 13J, and the voltage state, the frequency state, and the phase state are displayed. The image is displayed on the display means 32 via the display signal output circuit 31.

(Synchronous generator configuration)
In FIG. 2, the synchronous generator 50 is connected to the distribution line 3 via the switch 5B. In addition, the synchronous generator 50 is good also as a structure which incorporates the circuit breaker 4B.

  The synchronous generator 50 includes an automatic voltage regulator 50a for controlling the generated voltage and a governor 50b for controlling the frequency, and inputs the voltage control signal and the frequency control signal sent from the synchronous tester 1 through the transmission / reception circuit 50c. Control the voltage and frequency. The transmission / reception circuit 50 c sends the voltage signal Vg of the synchronous generator 50 to the synchronous tester 1 via the transmission / reception circuit 41.

(Signal example)
FIG. 4 is a signal example of the synchronous tester of the present invention, and shows the ground voltage Vrn of the 6.6 KV bus, the R-phase ground charging current Ir, the S-phase ground charging current Is, and the T-phase ground charging current It. Yes. The phase of the R-phase ground charging current Ir is advanced by π / 2 with respect to the ground voltage Vrn of the bus, and the phase of the ground voltage Vrn of the bus is obtained by delaying the phase of the ground charging current Ir by π / 2. Can do. Further, the ground charge currents Ir, Is, It of the R phase, the S phase, and the T phase are shifted in phase by 2π / 3.

[Another configuration example of synchronous tester and automatic synchronous injection device]
FIG. 5 is a block diagram for explaining another configuration example of the synchronous tester and the automatic synchronous input device. In the configuration for extracting the fundamental wave from the ground charging current, the fundamental wave in the arithmetic processing unit 13 shown in FIG. The difference is that the fundamental wave extraction circuit 14 performs the extraction means 13Dr, 13Ds, and 13Dt. Other configurations can be the same as those shown in FIG.

  The fundamental wave extraction circuit 14 performs analog signal processing on the ground charging currents Ir, Is, It and extracts a fundamental wave. One configuration example of the fundamental wave extraction circuit 14 is a low-pass filter circuit, which extracts frequency components in the frequency band of the fundamental wave by low-pass filter processing and extracts frequency components in the frequency band of the system voltage from the frequency components of the ground charging current. To do.

  The present invention is not limited to the above embodiments. Various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

  Since the synchronous tester and the automatic synchronous input device of the present invention do not require a voltage transformer or a voltage transformer for obtaining information on the frequency and frequency of the temporary power generator, 2 of the voltage transformer attached to the temporary power generator. Since problems related to the laying of the next signal cable or temporary installation of the instrument transformer on the distribution line can be avoided, restrictions on the generator installation location are reduced, and unnecessary power outages can be avoided when switching from temporary installation to main installation. The range of use is widened.

DESCRIPTION OF SYMBOLS 1 Synchronization tester 1A Phase detection means 1B Phase difference detection means 1C Synchronization point calculation means 1D Synchronization verification means 1E Fundamental wave extraction means 2 Bus 3 Distribution line 4A, 4B Breaker 5A, 5B Switch 6A, 6B, 6C Distribution line lead-out Power cable 7A, 7B, 7C Metal sheath grounding conductor 8A, 8B, 8C Current transformer for measuring ground charging current 9 Voltage acquisition means 9a Instrument transformer 9b Ungrounded transformer 10 Relay 11A-11D Level conversion circuit 12 Multiplexer 13 arithmetic processing unit 13A voltage detection means 13B frequency detection means 13C phase detection means 13Dv, 13Dr, 13Ds, 13Dt fundamental wave extraction means 13E frequency detection means 13F, 13Fs, 13Ft phase detection means 13G, 13Gs, 13Gt phase shift means 13H voltage comparison Means 13I Frequency comparison means 13J Phase difference comparison means 13 Soundness determination unit 13L synchronization test unit 13M voltage controller 13N frequency control means 13O display control unit 13a A / D converter 13b CPU
13c ROM
13d RAM
13e bus 14 fundamental wave extraction circuit 20 automatic synchronization input device 21 synchronization input circuit 31 display signal output circuit 32 display means 41 transmission / reception circuit 50 synchronous generator 50a automatic voltage regulator 50b governor 50c transmission / reception circuit 101 automatic synchronization input device 102 bus 103 distribution Electric wire 104A, 104B Circuit breaker 105A, 105B Closure 106A, 106B Instrument transformer 107 Generator 111 Synchronous tester 112 Synchronous input circuit A Signal cable B Signal cable Ir, Is, It Grounding current V Bus voltage Vg Voltage Signal Vl Line voltage Vrn Ground voltage

Claims (6)

In the synchronous tester that verifies the synchronization status of the parallel power system and the synchronous generator,
Phase detection means for detecting a wiring phase signal corresponding to the phase of the wiring voltage of the distribution line connected to the synchronous generator based on the fundamental wave component of the ground charging current on the synchronous generator side;
Based on the wiring phase signal and the system phase signal of the system voltage on the system side, phase difference detection means for detecting a phase difference between the phase of the system voltage and the phase of the wiring voltage;
A synchronization detector comprising synchronization point calculation means for calculating a synchronization point based on the phase difference.   The synchronous tester according to claim 1, further comprising an arithmetic circuit that executes the phase detection unit, the phase difference detection unit, and the synchronization point calculation unit by a calculation process of a computer. The phase detection means includes fundamental wave extraction means for extracting a fundamental wave component of the ground charging current,
The fundamental wave extracting means includes
The synchronous tester according to claim 2, wherein a frequency component in a frequency range of the system voltage is extracted from a frequency component of the ground charging current by discrete Fourier transform of a sampling value of the ground charging current or low-pass filter processing of the ground charging current. . The phase detection means includes fundamental wave extraction means for extracting a fundamental wave component of the ground charging current,
The synchronous tester according to claim 1, wherein the fundamental wave extracting means extracts a frequency component in a frequency region of the system voltage from a frequency component of the ground charging current by Fourier series expansion of the ground charging current.   The synchronous tester according to any one of claims 1 to 4, wherein the ground charging current is a current flowing through a grounding conductor of the distribution line. In the automatic synchronous injection device that parallel-synchronizes the synchronous generator with the power system,
A synchronous tester according to any one of claims 1 to 5;
An automatic synchronizer, comprising a synchronizer circuit for outputting a synchronizer command signal for causing the synchronous generator to system-parallel to the power system based on the synchronous point calculated by the synchronous point calculator.

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