JPH10336904A - Synchronizer for batch processing a plurality of generators - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of detection of synchronization between the voltage of the power system of commercial power supply and the voltage of synchronous generators, by finding differences in voltage value, frequency and phase between the power system and the synchronous generators. SOLUTION: A control unit 7 determines the difference in frequency between system- side voltage VSa and generator voltage VGa , the difference in voltage value between system-side voltage VSb and generator voltage VGb and the phase voltage values of the system-side voltage VSa and the generator voltage VGa . That is, if there is a request for applying synchronous generators to the power system and the difference between voltage VSb and voltage VGb disagrees with a reference value and the value for voltage VGb is high, an exciting current is reduced. If the difference in frequency between voltage VSa and voltage VGa disagrees with a reference value and the frequency of voltage VGa is high, supplied fuel is reduced. If the difference in voltage value between voltage VSb and voltage VGb , the difference in frequency between voltage VSa and voltage VGa , and the difference in phase between voltage VSa and voltage VGa , and all equal to the reference values, the control unit 7 outputs an application command to a sequencer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronization input device used when a synchronous generator is supplied to a power system, and more particularly to a synchronous device for a plurality of generators which collectively supplies a plurality of generators to the power system. About.

[0002]

2. Description of the Related Art Recently, not only a power system of a commercial power supply from a power company but also a self-powered generator equipped with a synchronous generator to supply electric power to loads such as elevators and electric lights has been developed. It is increasing. When the synchronous generator is supplied to the power system, if the difference between the voltage value, the phase, and the frequency of the two voltages is larger than a predetermined range, the synchronous generator or the breaker may be damaged by a transient current at the time of the supply. There is a possibility that it will. Therefore, in such a case, a synchronization input device that inputs the synchronous generator to the power system when the voltage generated by the synchronous generator is synchronized with the voltage of the power system is used.

[0003] A conventional synchronous input device will be described below.

FIG. 5 is a schematic diagram of a connection example between a power system and a synchronous generator.

A load 2 is connected to the power system 1,
A load 4 is connected to the synchronous generator 3. Power system 1
And the synchronous generator 3 are connected via a synchronous circuit breaker 5, and the synchronous circuit breaker 5 in the open state is closed as required (hereinafter also referred to as "closing of the synchronous circuit breaker"), and is connected to the power system. 1 and the synchronous generator 3 are electrically connected.

[0006] Voltage synchronous generator 3 generates V _G regulates the governor to control the amount of fuel to the prime mover rotating the synchronous generator 3, the magnitude of the exciting current flowing in the exciting coil of the synchronous generator 3 is controlled by the AVR, governor frequency of the voltage V _G by increasing the amount of fuel is increased, the voltage value becomes larger by increasing the excitation current by AVR. Such voltage control, the voltage V _G of the synchronous generator 3 occurs, for example, is to be equal to the voltage V _S of the electric power system 1 such as 50Hz with 6600 V.

However, as shown in FIG. 5, when the load 4 is connected to the synchronous generator 3, the load 4 constantly fluctuates so that, for example, the elevator operates and stops. voltage V _G of the synchronous generator 3 is generated so that fluctuates affected by this. For this reason, the synchronous input device operates the voltage V _G generated by the synchronous generator 3.
By but the voltage control described above, it sure to allow moment when synchronization is established between the voltage V _G of the voltage V _S and the synchronous generator 3 of the power system 1, the input of the synchronization circuit breaker 5, i.e. the power system 1 of the synchronous generator 3 To the system.

FIG. 6 is a schematic diagram of a conventional synchronous input device.

[0009] The voltage detector 6 outputs to the control unit 7 detects the voltage V _G of the voltage V _S and the synchronous generator 3 of the electric power system 1. Control unit 7 will later perform the determination process described with reference to FIGS. 7 and 8, the sequencer 8 when it is determined that synchronization with the voltage V _G of the voltage V _S and the synchronous generator 3 of the power system 1 is taken Outputs a throw command.

In the sequencer 8 receiving the turn-on command, the contact switch 9 is closed, and a current flows through the auxiliary relay 10. When a current flows through the auxiliary relay 10, the contact switch 12 closes and the closing coil 13 is energized, so that a current flows. When a current flows through the closing coil 13, the synchronous breaker 5 is closed, and the synchronous generator 3 is turned on to the power system 1. The contact switch 11 is a contact switch for preventing a malfunction. The contact switch 11 is closed before the synchronous breaker 5 is closed, and is opened when a current flows through the closing coil 13 and the synchronous breaker 5 is closed.

The reason why the contact switch 12 is not directly closed in response to the closing command from the control unit 7 but is via the contact switch 9 and the auxiliary relay 10 is that a relatively large current is required to turn on the synchronous circuit breaker 5. But the control unit 7
This is because the closing command cannot be turned on because the current is small, and the contact switch is amplified through the contact switch 9 and the auxiliary relay 10.

FIG. 7 is a block diagram showing the judgment processing in the control unit 7 shown in FIG. 6, and FIG. 8 is a flowchart of the judgment processing in the control unit 7 shown in FIG.

[0013] First, when a request for introduction into the power system 1 of the synchronous generator 3 (F-1), the voltage value of the voltage V _S of the power system 1 received from the voltage detector 6 and the synchronous generator 3 It compares the voltage value of the voltage V _G of, determining whether the difference ΔV is either within the reference value (F-2). If not within the reference value,
If the voltage value of the voltage V _G of the synchronous generator 3 is high (F-3)
The instructed to reduce the excitation current by AVR (F-4), directed to increase the exciting current by AVR when a low voltage value of the voltage V _G of the synchronous generator 3 (F-3) (F-5).

Next, the power system 1 received from the voltage detector 6
Of comparing the frequency of the voltage V _G of the frequency and the synchronous generator 3 of the voltage V _S, it is determined whether the difference ΔF Do reference values (F-6). If not within the reference value, the synchronous generator 3
If the frequency of the voltage V _G higher (F-7) is instructed to reduce the fuel supply by the governor (F-8), if a low frequency of the voltage V _G of the synchronous generator 3 (F-7 ) Is instructed by the governor to supply more fuel (F
-9).

[0015] Then, the voltage difference ΔV between the voltage value of the voltage V _G of the voltage value and the synchronous generator 3 of the voltage V _S of the power system 1 received from the detection unit 6, the power system 1 received from the voltage detector 6 voltage V _S of the frequency and the difference ΔF between the frequency of the voltage V _G of the synchronous generator 3, the voltage of the power system 1 received from the voltage detector 6 V _S
All of the difference Δθ between the phase and the synchronous generator 3 of the voltage V _G phase to determine whether reference values, respectively (F-1
0). If all of them are within the reference value, the control unit 7 outputs a closing command to the sequencer 8 (F-1).
1).

[0016]

[SUMMARY OF THE INVENTION In the above-described conventional synchronous feeding device is, for example, the voltage value of the voltage V _G of the voltage value and the synchronous generator 3 of the voltage V _S of the power system 1 received from the voltage detector 6 difference ΔV is within 5% difference ΔF between the frequency of the voltage V _G of the frequency and the synchronous generator 3 of the voltage V _S of the power system 1 received from the voltage detector 6 becomes within 0.2 Hz, and introducing synchronous generator 3 when the difference Δθ between the phase of the voltage V _G of the phase and synchronous generator 3 of the voltage V _S of the power system 1 received from the voltage detector 6 becomes within 5 degrees to the power system 1 Was supposed to.

However, in the case of the synchronization detection accuracy described above, when the synchronous generator is turned on, the maximum total generator capacity of the interconnected generator is not more than 20.
% Power swing occurs. That is, the power swing is 20% when there is only one generator connected, and there is no problem, but when there are a plurality of generators connected,
A power swing of (20% × the number of generators) will occur, and the power system will be greatly affected, causing a serious problem.

For this reason, when a plurality of generators are synchronously turned on, it is necessary to improve the detection accuracy of the synchronization detecting device in order to prevent a power swing.

However, conventionally, in order to improve the detection accuracy, a significant improvement in the detection unit is required, and there has been a problem that the cost is extremely high.

Before the interconnection, each generator operates independently, and when there is a load change, the voltage value and the frequency of the generated voltage fluctuate minutely. For this reason, there is a problem in that even if the voltage difference or the frequency difference is controlled by the synchronization detection device to match the power system of the commercial power supply, it cannot be simply and accurately adjusted.

The present invention has been made in view of the above points, and has an inexpensive configuration that can improve the accuracy of detecting the synchronization between the voltage of the power system of the commercial power supply and the voltage of the synchronous generator. The purpose is to provide.

[0022]

In order to achieve the above object, the present invention provides a voltage difference between a voltage value of a power system voltage and a voltage value of a voltage of a synchronous generator, a frequency of a voltage of a power system voltage, and When all of the phase difference between the frequency of the voltage of the synchronous generator and the phase of the voltage of the power system and the phase of the voltage of the synchronous generator are within a predetermined reference value, the synchronous generator and the In a synchronous input device for inputting the synchronous generator to the power system by turning on a circuit breaker for connecting to a power system, a voltage value of a waveform excluding only a top portion of a voltage waveform of the power system and By calculating a voltage difference between the voltage value of the waveform of the synchronous generator and the voltage remaining only at the top of the waveform, the voltage value of the voltage of the power system and the voltage value of the voltage of the synchronous generator are obtained. Find the value difference, By obtaining a frequency difference between the frequency of the waveform of the voltage waveform of the synchronous generator that leaves only the tail and the frequency of the waveform that leaves only the tail of the voltage waveform of the synchronous generator, The frequency difference between the frequency and the frequency of the voltage of the synchronous generator is obtained, and only the phase of the waveform of the voltage waveform of the power system except for the bottom portion of the voltage waveform and the top portion of the waveform of the voltage of the synchronous generator are determined. The phase difference between the phase of the voltage of the power system and the phase of the voltage of the synchronous generator is determined by determining the phase difference from the phase of the remaining waveform.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

In the present invention, the connection state between the power system and the synchronous generator and the schematic diagram of the synchronous input device are the same as those of the prior art, and will be described with reference to FIGS.

[0025] In the conventional synchronous feeding device, it has been inputted to the control unit 7 shown in as Fig. 6 a sinusoidal waveform of the voltage V _G of the voltage V _S and the synchronous generator 3 of the power system 1 shown in FIG. In such a method, a voltage detection error occurs about ± 1%.

In the present invention, first, the power system 1 shown in FIG.
It is made different from the conventional voltage detecting means for detecting the voltage V _G of the voltage V _S and the synchronous generator 3.

FIG. 1 is a diagram for explaining an embodiment of the voltage detecting means in the synchronization input device according to the present invention.
(A) is a block diagram of a means for detecting a voltage V _S of the power system 1, (b) is a block diagram of a means for detecting the voltage V _G of the synchronous generator 3.

The detection of the voltage V _S of the power system 1 is shown in FIG.
This is performed by detecting the voltage V _Sa and the voltage V _Sb shown in FIG. As shown in FIG. 1A, a circuit in which a double-wave rectifier diode circuit 20 and a resistor 21 are connected in series;
Circuit the a-wave rectifier diode circuit 22 and a resistor 23 connected in series, are connected in parallel to PT2 primary side of the AC voltage V _S. The potential difference between both ends of the double-wave rectifier diode circuit 20 is a voltage V _Sa , and the potential difference between both ends of the resistor 23 is a voltage V _Sb . As shown in FIG. 1B, a circuit in which a double-wave rectifier diode circuit 24 and a resistor 25 are connected in series, and a circuit in which a double-wave rectifier diode circuit 26 and a resistor 27 are connected in series, It is connected in parallel to PT2 primary side of the AC voltage V _G. And a double-wave rectifier diode circuit 2
The potential difference between both ends of the resistor 4 is a voltage V _Ga , and the potential difference between both ends of the resistor 27 is a voltage V _Gb . Here, the resistors 21, 2
It is desirable to use one having a high resistance value as 3, 25, and 27.

Here, the dual-wave rectifier diode circuits 20, 22, 24 and 26 shown in FIGS. 1A and 1B will be described.

FIG. 2 is an internal circuit diagram of the dual-wave rectifier diode circuit 20 shown in FIG.

As shown in FIG. 2, the dual-wave rectifier diode circuit 20 includes ten diodes connected in series, and ten diodes in opposite directions connected in parallel to the ladder type.
This is a configuration including a total of 20 diodes.

The dual-wave rectifier diode circuit 22 shown in FIG. 1A has the same configuration as the dual-wave rectifier diode circuit 20 except that the number of diodes is different, and 150 diodes are connected in series. In parallel with this, 150 diodes in the opposite direction are connected in a ladder shape, and the total number of diodes is 300.

The dual-wave rectifier diode circuit 24 shown in FIG. 1B has the same configuration as the dual-wave rectifier diode circuit 20. Ten diodes are connected in series, and the reverse direction is connected in parallel with the diode. Are connected in a ladder shape, and a total of 20 diodes are provided.

Further, the dual-wave rectifier diode circuit 26 shown in FIG. 1B has the same configuration as the dual-wave rectifier diode circuit 22. 150 diodes are connected in series.
In parallel with this, 150 diodes in the opposite direction are connected in a ladder shape, and the total number of diodes is 300.

[0035] FIG. 3, FIG. 1 (a), a diagram showing a waveform of a voltage detected by the embodiment shown in (b), (a) is PT2 primary side of the waveform of the voltage V _S, V _G (B) is a diagram showing waveforms of the voltages V _Sa and V _Ga , and (c) is a diagram showing the voltages V _Sb and V _Ga
FIG. 3 is a diagram illustrating a _Gb waveform.

As shown in FIG. 3B, the voltages V _Sa and V _Ga
The waveforms each voltage V _S, a waveform leaving only part of the skirt of V _G. As shown in FIG. 3C, the waveforms of the voltages V _Sb and V _Gb are waveforms leaving only the top portions of the voltages V _S and V _G , respectively.

Twenty double-wave rectifier diode circuits 20 and 24 are used respectively, and double-wave rectifier diode circuits 2 and 24 are used.
The 300 diodes used in each of 2 and 26 are diodes having a forward resistance value that causes a voltage drop of 0.7 V per each. Therefore, the voltage V
_S, the peak value of V _G is assumed to be 110V, 3
The peak values of the voltages V _Sa and V _Ga shown in FIG. 3B are 7 V, and the peak values of the voltages V _Sb and V _Gb shown in FIG.
In the present embodiment, the voltages V _Sa , V _Ga , V _Sb , V
_Gb is input to the control unit 7 shown in FIG.

FIG. 4 shows how the voltages V _Sa , V _Ga , V _Sb and V _Gb detected in the embodiment shown in FIGS. 1A and 1B are input to the control unit 7 shown in FIG. FIG.

As can be seen with reference to FIG. 4, the control unit 7 determines the frequency difference between the system side voltage V _Sa and the generation electromotive voltage V _Ga, and obtains the voltage difference between the system side voltage V _Sb and the generation electromotive voltage V _Gb. A value difference is determined, and a phase voltage value difference between the system side voltage V _Sa and the power generation electromotive voltage V _Ga is determined. Then, the control unit 7 shown in FIG.
The operation is performed as shown in the flowchart of the determination process in.

That is, first, when there is a request to supply the synchronous generator 3 to the power system 1 (F-1), the voltage value of the voltage V _Sb is compared with the voltage value of the voltage V _Gb , and the difference is determined. It is determined whether ΔV is within the reference value (F-2). If the value is not within the reference value and the voltage value of the voltage _VGb is high (F-3), an instruction is issued to reduce the exciting current by AVR (F-3).
-4), when the voltage value of the voltage _VGb is low (F-3), A
Instruct VR to increase the exciting current (F-
5).

Next, the frequency of the voltage V _Sa is compared with the frequency of the voltage V _Ga to determine whether or not the difference ΔF is within a reference value (F-6). When the frequency is not within the reference value and the frequency of the voltage V _Ga is high (F-7), the governor is instructed to reduce the supplied fuel (F-8), and when the frequency of the voltage V _Ga is low (F- In 7), the governor is instructed to increase the supplied fuel (F-9).

The difference ΔV between the voltage value of the voltage V _{Sb and} the voltage value of the voltage V _Gb , the difference ΔF between the frequency of the voltage V _{Sa and} the frequency of the voltage V _Ga , the phase of the voltage V _{Sa and} the phase of the voltage V _Ga And the difference Δ
It is determined whether all of θ are within the reference values (F-10). If all of them are within the reference value, the control unit 7 outputs an input command to the sequencer 8.

By the way, in the present invention, the AV
The control of R and governor is not performed for all of the plurality of interconnected generators. For example, when five interconnected generators are operating, there is a margin in the output of them. AVR or governor control may be performed only for two units. By doing so, synchronization can be easily achieved even when the load (for example, power consumption by the elevator) fluctuates.

Incidentally, in the synchronization input device according to the present invention, the operation up to the synchronization input may be described below.

For example, when five generators perform synchronous input during operation, two of the generators are operated until the voltage difference is within 5% and the frequency difference is within 0.2 Hz. Controls AVR and governor. If the voltage difference is within 5% and the frequency difference is within 0.2 Hz, until the condition that the voltage value difference is within 2%, the frequency difference is within 0.05 Hz, and the phase difference is within 2 degrees is satisfied. wait. During this waiting, there is usually a load fluctuation of the elevator etc.
It is considered that the above condition is satisfied without controlling the AVR or the governor. However, in consideration of the fact that there is no load change, the above-described condition is satisfied, for example, once every 30 seconds.
AVR or governor control may be performed on one generator. Then, when the above condition is satisfied, the synchronous breaker is turned on.

In the conventional synchronous input device, if the input condition is not satisfied within about 180 seconds from the start of the synchronous control, the synchronous control is automatically stopped. Waiting for about 10 minutes after the condition that the voltage value difference is within 5% and the frequency difference is within 0.2 Hz provides a margin for entering the synchronization input range.

As described above, in the present invention, the voltage V
_{Since Sa} , V _Sb , V _Ga , and V _Gb are set to voltages of less than 10 V, which can be easily handled by an electronic circuit, and a converter is not required, the detection accuracy can be improved.

[0048]

As described above, according to the present invention,
With a low-cost configuration, it is possible to provide a synchronization input device that can improve the detection accuracy of synchronization between the voltage of the power system of the commercial power supply and the voltage of the synchronous generator.

[Brief description of the drawings]

[1] is a diagram for explaining an embodiment of the voltage detecting means in synchronism dosing device according to the present invention, (a) shows the block diagram of a means for detecting a voltage V _S of the power system, (b) the synchronous generator it is a block diagram of a means for detecting the voltage V _G of the machine.

FIG. 2 is an internal circuit diagram of the dual-wave rectifier diode circuit shown in FIG.

3A and 3B are diagrams showing waveforms of voltages detected in the embodiment shown in FIGS. 1A and 1B, wherein FIG. 3A shows voltages V _S and V
FIG. 7B is a diagram illustrating a waveform of _G , FIG. 7B is a diagram illustrating waveforms of voltages V _Sa and V _Ga , and FIG. 7C is a diagram illustrating waveforms of voltages V _Sb and V _Gb .

FIG. 4 is a diagram for explaining how to input voltages V _Sa , V _Ga , V _Sb , and V _Gb detected in the embodiment shown in FIGS. 1A and 1B to the control unit shown in FIG. 6; It is.

FIG. 5 is a schematic diagram of a connection example between a power system and a synchronous generator.

FIG. 6 is a schematic view of a conventional synchronous input device.

FIG. 7 is a block diagram showing a judgment process in the control unit shown in FIG. 6;

8 is a flowchart of a determination process in the control unit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power system 2, 4 Load 3 Synchronous generator 5 Synchronous breaker 5 6 Voltage detector 7 Control unit 8 Sequencer 9, 11, 12 Contact switch 10 Auxiliary relay 13 Input coil 20, 22, 24, 26 Dual-wave rectifier diode circuit 21, 23, 25, 27 resistors

Claims (6)

[Claims] 1. A voltage difference between a voltage value of a voltage of a power system and a voltage value of a voltage of a synchronous generator, a frequency difference between a frequency of a voltage of a power system and a frequency of a voltage of a synchronous generator, and a voltage of a power system. When all of the phase differences between the phase of the synchronous generator and the phase of the voltage of the synchronous generator are within a predetermined reference value, the synchronous generator is turned on by turning on a circuit breaker connecting the synchronous generator and the power system. A synchronous input device for inputting the power to the power system, wherein the voltage value of the waveform leaving only the top portion of the voltage waveform of the power system and the waveform leaving only the top portion of the voltage waveform of the synchronous generator The voltage value difference between the voltage value of the power system and the voltage value of the voltage of the synchronous generator is obtained by calculating the voltage value difference from the voltage value of the power system. Frequency of waveform leaving only The frequency difference between the frequency of the voltage of the power system and the frequency of the voltage of the synchronous generator is determined by determining the frequency difference between the frequency of the voltage of the synchronous generator and the frequency of the waveform that leaves only the bottom of the waveform of the synchronous generator. Determining the phase difference between the phase of the waveform of the power system voltage waveform leaving only the bottom portion thereof and the phase of the waveform leaving only the top portion of the synchronous generator voltage waveform, A synchronous input device for determining a phase difference between a phase of a voltage of a system and a phase of a voltage of the synchronous generator. 2. A waveform in which only a top portion of a voltage waveform of the power system is left, a waveform in which only a top portion of a voltage waveform of the synchronous generator is left, and a waveform of a voltage waveform in the power system. 2. A double-wave rectifier diode circuit and a resistor for creating a waveform that leaves only a portion and a waveform that leaves only a bottom portion of the voltage waveform of the synchronous generator are provided. Synchronous input device. 3. A waveform in which only a top portion of a voltage waveform of the power system is left, a waveform in which only a top portion of a voltage waveform of the synchronous generator is left, and a waveform of a voltage waveform in the power system. 2. The synchronous input device according to claim 1, wherein the peak value of the waveform excluding only the portion and the waveform excluding only the bottom portion of the voltage waveform of the synchronous generator is substantially less than 10 V. 3. 4. A method according to claim 1, wherein a plurality of said synchronous generators are supplied to said electric power system, and said plurality of synchronous generators are used to synchronize the voltage of said electric power system with the voltage of said plurality of synchronous generators. The synchronous input device according to claim 1, wherein the synchronous input device performs AVR control and governor control of a part of the synchronous generator. 5. The AVR control and the governor control are performed until the voltage difference is within approximately 5% and the frequency difference is within approximately 0.2 Hz, and the voltage difference is within approximately 5% and the frequency difference is within a range. If it is almost within 0.2Hz,
Wait until the condition that the voltage difference is approximately 2% or less, the frequency difference is approximately 0.05 Hz and the phase difference is approximately 2 degrees are satisfied, and the voltage difference is approximately 2% and the frequency difference is When the condition within approximately 0.05 Hz and the phase difference is approximately within 2 degrees is satisfied, the synchronous generator is turned on by turning on the synchronous breaker that connects the synchronous generator and the power system. A synchronous input device for inputting to an electric power system. 6. The method according to claim 1, wherein the voltage difference is within approximately 2%, the frequency difference is within approximately 0.05 Hz, and the phase difference is approximately 2%.
6. The synchronous input device according to claim 5, wherein a waiting time until a condition within a degree is satisfied is about 10 minutes.