JPH08149697A - Parallel operation detector for generator - Google Patents

Abstract

PURPOSE: To decide whether a non-utility generator is operating in parallel with a commercial power supply or not easily and surely. CONSTITUTION: A consumer is equipped with a non-utility generator G and receives power from a commercial power supply through a system line F. Under a state where the power factor of the generator is detected through a power factor detector PF and the generator voltage is detected through a voltage detector V, field of the generator G is increase or decreased by means of a field current setter 1. A decision is made that the generator is operating in parallel with the commercial power supply if the power factor of the generator varies whereas a decision is made that the generator is operating independently if the generator voltage varies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator parallel operation detecting device, and is devised so as to easily and accurately detect whether a private generator is operating in parallel with a commercial power source.

[0002]

2. Description of the Related Art An example of an electric system in a customer equipped with a private generator will be described with reference to the single line connection diagram of FIG. As shown in FIG. 2, a self-exciting private generator (synchronous generator) G is provided in the customer's premises, and an automatic voltage regulator A is provided.
VR detects the generator voltage via the instrument transformer PT,
The field is adjusted so that the detected voltage becomes the set voltage.
This premises is provided with a premises wire L _{1 having a} voltage of 10 KV, a premises wire L _{2 having} a voltage of 20 KV, and various loads (not shown). The voltage of ₁₀ KV generated by the generator G is boosted to 20 KV by the transformer T ₁ .

A commercial system electric wire F is provided outside the premises, and a commercial voltage of 70 KV is stepped down to 20 KV by transformers T ₂ and T ₃ and introduced to the local electric wire L ₂ .

Circuit breakers CB ₁₁ , CB ₂₁ , CB ₃₁ ,
CB ₃₂ , CB ₄₁ , CB ₄₂ , CB ₄₃ , CB ₄₄ , CB ₅₁ , C
B ₅₂ is arranged, and circuit breakers CB ₆₁ and CB ₆₂ are installed outside the building.
Is arranged.

Conventionally, it is necessary to determine whether or not the private generator G on the premises is operating in parallel with the commercial power source.
To the commercial system power supply F, the open / close state of the breaker provided in the path is detected and determined. That is, if at least one of the paths between the generator G and the system power supply F is closed, it is determined that the circuit breakers are operating in parallel, and all the paths are closed. If even one is open, it is determined not to be parallel operation.

For example, the circuit breakers CB ₁₁ , CB ₂₁ , CB ₃₁ , C
If B ₄₁ , CB ₅₁ , and CB ₆₁ are all closed, it is determined that they are operating in parallel. Of course, the same determination is made for the other paths between the generator G and the system electric wire F, and if all the circuit breakers in the paths are closed in at least one circuit of each path, the parallel connection is performed. It is determined to be driving.

Depending on whether or not they are in parallel operation,
Since the operating states of the transverse compensation device of the automatic voltage regulator AVR and the droop / speed control of the governor are changed, it is necessary to judge the parallel operating state.

[0008]

By the way, in the above-mentioned conventional technique, there are many paths between the generator G and the system electric wire F, and whether all the circuit breakers are closed in each path. Since it could be investigated, it was troublesome to make a judgment and it was troublesome.

In view of the above-mentioned prior art, it is an object of the present invention to provide a generator parallel operation detecting apparatus capable of easily detecting the parallel operation state.

[0010]

Means for Solving the Problems The structure of the present invention which achieves the above-mentioned object is provided with a private generator which is a synchronous generator, and in a power demand section which receives power from a commercial power source, A field current setting device that increases or decreases a field current at fixed time intervals, a voltage detector that detects a generator voltage of the private generator, and a power factor detector that detects a generator power factor of the private generator. It is characterized by having.

[0011]

In the present invention, the field current setting device increases or decreases the field of the private generator at regular time intervals. Since the generator power factor detected by the power factor detector changes during parallel operation, and the generator voltage changes during isolated operation, the operating state can be determined.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same parts as those of the conventional technique are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 shows an embodiment of the present invention. As shown in the figure, a power factor detector PT and a transformer CT are connected to a local electric wire L ₁ to which electric power of a private generator G which is a synchronous generator is sent.
Is provided. The voltage detector V is a voltage transformer PT
It is connected to the secondary side of and detects the generator voltage of the generator G. The power factor detector PF detects the generator power factor of the generator G based on the current input via the transformer CT and the voltage input via the instrument transformer PT.

The field current setter 1 is an automatic voltage regulator AV.
The field current change command 1a is output to R. When the field current change command 1a is output, the field current of the generator G is increased or decreased at regular intervals (for example, 0.1 second intervals) through the automatic voltage regulator AVR.

Since the generator G is a synchronous generator, as well known, it operates as follows. When the generator G is not operating in parallel with the commercial power supply but is operating independently, the generator voltage increases when the field current increases, and the generator voltage decreases when the field current decreases. Even if the field current is changed while the generator G is operating in parallel with the commercial power supply, the capacity of the commercial power supply system is larger than the generator capacity, so the generator voltage does not change, and the generator power factor does not change. Changes.

Therefore, when the field current is increased or decreased,
When the generator voltage detected by the voltage detector V changes, it can be determined that the generator G is operating alone.

When the generator power factor detected by the power factor detector PF changes when the field current is increased or decreased, it can be determined that the generator G is operating in parallel with the commercial power source.

[0018]

According to the present invention as described in detail with reference to the above embodiments, by simply detecting the generator voltage and the generator power factor when the field of the private generator is changed, It is possible to reliably determine whether it is the parallel operation state or the independent operation state.

[Brief description of drawings]

FIG. 1 is a single wire connection diagram showing an embodiment of the present invention.

FIG. 2 is a single-line connection diagram showing a conventional technique.

[Explanation of symbols]

G Private generator AVR Automatic voltage regulator PT Meter transformer L ₁ , L _{2 In-} house wires T ₁ , T ₂ , T ₃ Transformer F System wire CB _{11 to} CB ₆₂ Circuit breaker V Voltage detector PF Power factor detector CT transformer 1 field current setting device 1a field current change command

Claims (1)

[Claims] 1. A field current setter for increasing or decreasing a field current of the private generator in a power demand section that includes a private generator that is a synchronous generator and receives power from a commercial power source. And a voltage detector that detects a generator voltage of the private generator, and a power factor detector that detects a generator power factor of the private generator. .