JPH06311794A - Detector for single operation of generator - Google Patents

Abstract

PURPOSE:To make it possible to detect a generator being in single operation by detecting the presence of output of one receiver and the absence of that of the other. CONSTITUTION:With a water-wheel generator 16 placed in an electric power system 6 in parallel, both of a system breaker 5 and a generator bus breaker 7 are closed; the frequency signal 1A from an oscillator 1 is received by a receiver 11, and that 2A from a modulator 2 is received by another receiver 13. Therefore, one output contact 11A is open, and the other 13A is closed. The AND condition of the output contacts 11A and 13A does not hold, and consequently, the output of single operation signal is not produced. With the water-wheel generator 16 not placed in the electric power system 4 in parallel, contrarily, the system breaker 5 or the generator bus breaker 7 is open; the frequency signal 1A breaks and is not received by the receiver 11. However, the frequency signal 2A is received by the receiver 13, and the output contact 13A is closed. Consequently, the AND condition of the output contacts 11A and 13A of the receivers 11 and 13 hold, and the output of single operation signal is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an islanding operation detecting device for detecting islanding operation of a hydroelectric generator that is disconnected from a system bus in a hydroelectric power plant, for example.

[0002]

2. Description of the Related Art For example, in a hydroelectric power plant, the flow rate of a turbine is set as a speed control operation to control the rotational speed of the turbine to be a synchronous speed before parallel input to the system, but after parallel input, the flow rate of a flow-type power plant is set to The automatic water level adjustment operation is performed to control the generator output (active power) according to the level, and the automatic load adjustment operation is controlled to control the generator output (active power) at the dam power station. There is.

In order to prevent the disturbance of the turbine, since the turbine generator has a very large inertia before parallel insertion into the system, it is necessary to strengthen elastic restoration (damping) to prevent overshooting operation. It is necessary to switch the elastic restoration (damping) before and after the loading.

Further, as the excitation control of the generator, an automatic voltage adjustment operation for controlling the voltage of the generator to be constant (rated voltage) before parallel input to the system, and to control the power factor of the generator to be constant after parallel input. Automatic power factor adjustment operation is performed.

As described above, it is necessary to switch the control of the turbine generator depending on whether or not the turbine generator is connected in parallel to the system, and in particular, the load is placed on the distribution line without being connected to the system in parallel. This is important when operating alone. In addition, depending on the power plant, the quality of the electric power (voltage and frequency fluctuation) during the islanding operation deteriorates. Therefore, in the case of the islanding operation, the distribution line load is disconnected, that is, the islanding operation may not be performed.

FIG. 2 is a system configuration diagram for explaining a conventional general islanding detection method. In FIG. 2, the water turbine generator 16 is connected to the generator busbar 8 via a generator parallel breaker, and this generator busbar 8 is connected to the system busbar 4 via the generator busbar breaker 7 and the system breaker 5. It is based. Further, a distribution line load 19 is connected to the generator bus 8 via a distribution line breaker 17 and a distribution line transformer 18.
Are connected. Further, an excess / deficiency frequency relay 21 is connected to the generator bus 8 via an instrument transformer 20.

In a power plant having such a system configuration, when the system breaker 5 is opened due to a system accident or the like, the generator 16 becomes a load interrupter, and the generator rotates according to the difference between the generator output and the distribution line load. The number (frequency) fluctuates. In many cases, the distribution line load is smaller than the generator output, so the generator rotation speed (frequency) increases.

This frequency fluctuation is caused by an excessive or insufficient frequency relay 21
Is detected by the output contact 21A after a certain period of time.
It is judged that it is an independent operation by the closed circuit of the
The load on the distribution line is disconnected by opening 7.

[0009]

However, when the system breaker 5 is opened due to a system accident or the like as described above, the generator output suddenly changes the load in the same manner as the load on the distribution line, causing frequency fluctuations. However, when the difference between the generator output and the distribution line load is extremely small, the frequency fluctuation does not occur so much, and the detection by the excess / deficiency frequency relay 21 becomes impossible.

Even when the excess / deficiency frequency relay 21 can be detected, after the system breaker 5 is opened, the excess / deficiency frequency relay 21 operates due to the fluctuation of the frequency of the turbine generator, and the confirmation time (generally 0.5 to Since it is determined that the islanding operation is performed after about 3 seconds), there is a problem that it takes time to detect.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to detect an islanding operation of a generator quickly and reliably and to cope with a wide range even in a complicated electric power system. An object is to provide a generator independent operation detection device.

[0012]

In order to achieve the above object, the present invention is a power plant in which a generator bus is connected to a system bus via a circuit breaker, and the generator is connected to the generator bus. A first signal generator for outputting a frequency signal to the system bus via an instrument transformer, and a frequency signal in a band different from the frequency band of the first signal generator from the instrument transformer. A second signal generator for output to a system bus via the second bus and a frequency in the frequency band of the second signal generator connected to both ends of the circuit breaker through coupling transformers regardless of the open / close state of the circuit breaker. A bandpass filter for passing only signals and a frequency signal transmitted from the first and second signal generators to the generator bus through the transformer for instrument and transmitted through the system bus and the generator bus, respectively. Received separately Receiving a frequency signal of the second signal generator transmitted through the bandpass filter by the one receiver when the breaker is opened, and the other receiver receives the frequency signal of the first signal. And a discriminating means for discriminating that the generator is in the independent operation on condition that the frequency signal of the generator is not received.

[0013]

In the generator isolated operation detecting apparatus having such a configuration, the frequency signal output from the first signal generator and the first signal generator output from the second signal generator are provided. When the frequency signals of different frequency bands are transmitted to the system bus through the instrument transformer, the frequency signals of the first and second signal generators are interrupted when the circuit breaker is turned on. Through the bandpass filter, the frequency signals of the second signal generator are transmitted to the generator busbar, and these frequency signals are received by receivers respectively connected to the generator busbar via an instrument transformer. . In such a state, if the circuit breaker opens the circuit due to a system fault or the like, the frequency signal of the first signal generator is cut off, but the frequency signal of the second signal generator is transmitted to the generator bus through the bandpass filter. This frequency signal is received by one receiver. Therefore, it is possible to determine that the generator is in the independent operation on the condition that one receiver has an output and the other receiver has no output.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the system configuration of a hydroelectric power plant to which the islanding operation detection device for a hydroelectric power plant according to the present invention is applied. In FIG. 1, a water turbine generator 16 is connected to a generator busbar 8 via a generator parallel breaker.
Is connected to the system bus 4 via a generator bus breaker 7 and a system breaker 5. A distribution line load 19 is connected to the generator bus 8 via a distribution line breaker 17 and a distribution line transformer 18.

In a hydroelectric power plant having such a structure, an oscillator 1 for outputting a frequency signal 1A and a modulator 2 for converting the frequency signal 1A output from the oscillator 1A into a frequency signal 2A in a different frequency band are used for measuring instruments. It is connected to the system bus 4 via the transformer 3.

A bandpass filter 5A is connected to both ends of the system breaker 5 via coupling transformers 5B and 5C, and a coupling transformer 7 is also connected to both ends of the generator bus breaker 7.
B. The bandpass filter 7A is connected via 7C.

Further, a bandpass filter 10 and a receiver 11, and a bound pass filter 12 and a receiver 13 are connected in series to the generator bus 8 via an instrument transformer 9, respectively. In this case, the bandpass filter 10 inputs to the receiver 11 only via the frequency signal 1A in the frequency band of the oscillator 1, and the bandpass filter 12 inputs to the receiver 13 only via the frequency signal 2A in the frequency band of the modulator 2. It is a thing. Further, when the receiver 11 receives the frequency signal 1A, its output contact 11A opens, and when the receiver 13 receives the frequency signal 2A, its output contact 13A closes. When the AND condition of these output contacts 11A and 13A is satisfied, The operation signal 14 is output.

Next, the operation of the generator independent operation detecting device configured as described above will be described. Now, it is assumed that the frequency signal 1A is transmitted from the oscillator 1 and the frequency signal 2A is transmitted from the modulator 2 to the system bus 4 via the instrument transformer 3. Then, the frequency signal 1A of the oscillator 1 is transmitted from the system bus 4 to the generator bus 8 via the system breaker 5, the power system line 6, and the generator bus breaker 7.

Further, the frequency signal 2A of the modulator 2 is transmitted from the system bus 4 to the power system line 6 via the system breaker 5 or the coupling transformers 5B and 5C and the bandpass filter 5A, and further the generator bus is cut off. Device 7 or coupling transformer 7
It is transmitted to the generator bus 8 via B, 7C and the bandpass filter 7A.

Therefore, when the system breaker 5 and the generator bus breaker 7 are closed, the frequency signal 1A of the oscillator 1 and the frequency signal 2A of the modulator 2 are generated by the generator bus 8.
Will be transmitted to.

Further, these frequency signals 1A and 2A are respectively inputted to receiving bandpass filters 10 and 12 which are connected to the generator bus 8 through an instrument transformer 9. The reception band pass filter 10 allows only the frequency signal 1A in the frequency band of the oscillator 1 to pass, and when received by the receiver 11, the output contact 11A thereof is opened. Further, the reception band pass filter 12 allows only the frequency signal 2A in the frequency band of the modulator 2 to pass therethrough, and when received by the receiver 12, the output contact 12A thereof is closed.

From the above, when the turbine generator 16 is connected in parallel to the power system, the system breaker 5 and the generator bus breaker 7 are closed, so that the oscillator 1
Since the frequency signal 1A in the frequency band of 1 is received by the receiver 11 and the frequency signal 2A of the modulator 2 is received by the receiver 13, these output contacts 11A open and
A closes. As a result, the AND condition of the output contacts 11A and 13A is not satisfied, so that the isolated operation signal is not output.

On the other hand, when the turbine generator 16 is not connected to the power system 4 in parallel, that is, in the isolated operation, the system breaker 5 or the generator bus breaker 7 is open, so that the frequency signal of the oscillator 1 is generated. 1A is disconnected and is not received by the receiver, but the frequency signal 2A of the modulator 2 is received by the receiver 13 and its output contact 13A is closed, so that the output contacts 11A, 1 of these receivers 11 and 13 are closed.
The AND condition of 3A is satisfied, and the islanding operation signal is output. Therefore, when the water turbine generator 16 is disconnected from the system bus 4 and operated independently, it can be detected quickly and reliably.

[0024]

As described above, according to the present invention, it is possible to quickly and surely detect the islanding operation of the generator and also to cope with a wide range even in a complicated power system. Can be provided.

[Brief description of drawings]

FIG. 1 is a system configuration diagram for explaining an embodiment of a generator isolated operation detecting device of the present invention.

FIG. 2 is a system configuration diagram for explaining a conventional generator isolated operation detecting device.

[Explanation of symbols]

1 ... Oscillator, 1A ... Frequency signal, 2 ... Modulator,
3, 9 ... Instrument transformer, 4 ... System bus, 5 ... System breaker, 5A, 7A ... Bandpass filter, 5B,
5C, 7B, 7C ... coupling transformer, 6 ... power system line,
7 ... Generator bus breaker, 8 ... Generator bus 10,
12 ... bandpass filter for reception, 11, 13 ... receiver, 15 ... generator parallel breaker, 16 ... turbine generator, 17 ... distribution line breaker, 18 ... distribution line transformer,
19 …… Distribution line load.

Claims (2)

[Claims] 1. In a power plant in which a generator bus is connected to the system bus via a circuit breaker, and a generator is connected to the generator bus, a frequency signal is sent to the system bus via an instrument transformer. And a second signal generator for outputting a frequency signal in a band different from the frequency band of the first signal generator to the system bus through the instrument transformer, A bandpass filter connected to both ends of the circuit breaker via a coupling transformer to pass only a frequency signal in the frequency band of the second signal generator regardless of the open / closed state of the circuit breaker; and the generator busbar. Receivers respectively connected through a transformer for meters and respectively receiving frequency signals transmitted from the first and second signal generators through the system bus and the generator bus, and the receiver when the breaker is opened. Receive one Generator receiving the frequency signal of the second signal generator transmitted by the transmitter through the bandpass filter, and the other receiver not receiving the frequency signal of the first signal generator. And a discriminating means for discriminating that the generator is in an isolated operation. 2. The generator islanding detection device according to claim 1, wherein the first signal generator is composed of an oscillator that generates a frequency signal in a certain frequency band, and the second signal generator is the first signal generator. A generator independent operation detecting device comprising a modulator that converts a frequency signal output from a signal generator into a frequency signal in a different frequency band.