JPS5953780B2 - Parallel operation generator disconnection control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 7. The present invention relates to a control circuit for a parallel operation generator.

Generally, generators that operate in parallel are equipped with an automatic voltage regulator (
(hereinafter referred to as an AVR), and this AVR further includes a cross-current compensator.

In this case, the cross current compensator is adjusted on the premise that each generator receives a load distribution of active power and reactive power proportional to its rated capacity. For this reason, the following problem usually occurs when the generators operating in parallel are disconnected from the operating system, so-called decoupling. In other words, when performing the above-mentioned disconnection, the governor is operated to transfer the active power, but the governor cannot transfer the reactive power, so it is difficult to disconnect the parallel with the reactive current remaining. This has an adverse effect on the contact life of the circuit breaker (hereinafter referred to as ACB). On the other hand, in order to eliminate this drawback, it is possible to transfer active power by operating the governor, then manually adjust the AVR's voltage setting device to transfer reactive power, and then perform decoupling. This method has the drawback that it requires a very troublesome operation, it is difficult to automate the process of disassembling the array, and it is not possible to perform the disassembly quickly. Therefore, an object of the present invention is to transfer not only active current but also reactive current to other generators that are continuously operating with a simple operation when disconnecting generators in parallel operation.
It is an object of the present invention to provide a parallel disconnection control circuit which can automate the parallel disconnection operation while preventing damage to the contacts such as the above. In order to achieve such an object, the present invention comprises a series disconnection control circuit that changes the degree of drooping characteristics when the reactive current shifts.
This will be explained in detail using an example.

Figure 1 is a circuit diagram showing the circuit configuration of the first generator of generators operated in parallel;
is an AVR, 3 is a voltage detection transformer, 4 is a current transformer for cross current compensation, and 5 is five resistors for cross current compensation.

FIG. 2 shows a vector diagram of the detected voltage in the circuit configuration shown in FIG. 4 and the voltage 4 detected and converted by the cross current compensation resistor 5. Vector V3 is vector V1 and V
2, and this voltage is obtained by combining AVR
Based on this input, the voltage is controlled by AVR2. For this purpose, generator 1
can maintain the drooping characteristics shown in FIG. In addition, in FIG. 2, φ indicates the load power factor angle. Normally, the drooping characteristics of the generator 1 shown in FIG. 3 and the drooping characteristics of other generators are set to be equal. Note that the load current ratio shown in FIG. 3 is expressed as (load current/rated current)×100%. Fourth
The figure is a circuit diagram showing an embodiment of the parallel-operated generator parallel disconnection control circuit according to the present invention, and the same parts as in FIG. 1 are denoted by the same reference numerals.

In the figure, 1a is a first alternating current generator, 4a is a cross current compensation current transformer provided in this output circuit, 1b is a second alternator, and 4b is a cross current current transformer provided in this output circuit. This is a compensation current transformer. Reference numerals 8a and 8b are first and second differential current transformers whose input sides are connected to the cross-current compensating current transformers 4a and 4b, respectively, and these are designed to be cross-connected.

Differential current transformers 8a and 8b have first output sides 8a1 and 8b, respectively.
8b1 and second outputs 8a2, 8b2, the second outputs 8a2 and 8b2 being cross-connected. Note that the output side 8a1 of the differential current transformer 8a
are connected to both ends of the cross current compensation resistor 5. In addition,
Although not shown in Fig. 4, the second AC generator 1b side has a voltage detection transformer, a cross current compensation resistor, and an automatic voltage A regulating device is connected, and a first output 8b1 of a differential current transformer 8b is connected to both ends of this cross-current compensation resistor. 9 is a changeover switch, the movable contact 9a of which is connected to one end of the output side 8b2 of the differential current transformer 8b, and the fixed contact 9
b is one end of the output side 8a2 of the differential current transformer 8a, the fixed contact 9
C is connected to the other end.

By switching the changeover switch 9 as shown by the solid line, the output sides 8a2 and 8b2 of both differential current transformers 8a and 8b can be connected crosswise, and by switching the switch 9 as shown by the broken line, the output of the differential current transformer 8a can be connected. The configuration is such that the side 8a2 can be opened and the output side 8b2 of the differential current transformer 8b can be shorted. In such a configuration, when transferring the load from the alternator 1a to the alternator 1b, first transfer the active power, then switch the changeover switch 9 from the state shown by the solid line to the state shown by the broken line, and then change the differential voltage. The output side 8a2 of the flow vessel 8a is opened.

As a result, a large current flows through the output side 8a1 of the differential current transformer 8a, and the voltage drop across the cross current compensation resistor 5, that is, the second
Vector 2 shown in the figure becomes larger. Therefore, the voltage characteristic changes from the solid line characteristic a to the chain line characteristic b, as shown in FIG. 5, and the reactive current can be shifted. In this case, since the second output side 8b2 of the differential current transformer 8b is short-circuited by the changeover switch 9, most of the output current of the differential current transformer 8b is transferred to the short-circuited second output side 8b2. Flowing to the first
The current on the output side 8b1 of the AC generator 1b becomes small.
The characteristics also change from d to C as shown. That is, the fifth
In the voltage characteristics shown in the figure, during parallel single parallel operation, the load current is balanced in terms of voltage at points A and C, respectively, and the operation is 0A = 0C, but by shifting the load, the The load current ratio on the side that carries the load is small, and the load current ratio on the side that carries the load is large, causing a significant shift in the point of the load current, resulting in a difference in the generated voltage and a cross current, and this cross current causes an imbalance. It will be preserved.

Therefore, by switching the changeover switch 9 as described above, the voltage characteristic of the alternating current generator 1a on the disconnected side becomes a steep drooping characteristic as shown in b; The side that bears the load is now balanced at 0B, and the degree of cross current occurrence is greatly reduced. When the reactive current is transferred by the method described above, the AC generator 1a is disconnected from the BUS by turning off ACBa, and the changeover switch 9 is returned to its original state to return to the normal cross current compensation state. machine] can complete the disassembly of machine a. Therefore, since the ACB can be disconnected while the reactive current is being transferred, damage to the ACB can be prevented, and since the reactive current can be transferred by simply switching the changeover switch, it is possible to automate the disconnection operation. .

FIG. 6 is a circuit diagram showing another embodiment, and the same parts as in FIG. 4 are designated by the same reference numerals.

Note that the output side 8a2 of the differential current transformer 8a is connected to the output side 8b2 of the differential current transformer 8b in a crosswise manner as in FIG. 4. 10 is a resistor connected between the voltage detection transformer 3 and the cross-current compensation resistor 5, ] ] is the one end of the cross-current compensation current transformer 4 (alternating current generator 1a side) and the differential current transformer This is a contact point connected between the terminal 8a and one end of the terminal 8a.

The contact 11 and the resistor 10 are connected in parallel with each other at both ends thereof. Although omitted in FIG. 6, the second AC generator 1b side is also equipped with a voltage detection transformer, a cross current compensation resistor, and an automatic voltage converter, just like the first AC generator 1a side. A regulating device, a current transformer for cross-current compensation, a differential current transformer, a resistor and contacts are connected. The first output side of this differential current transformer is connected to both ends of the cross current compensation resistor, and the second output side is connected to the second output side 8a2 of the differential current transformer 8a.
and are differentially connected. In such a configuration,
By turning off the contact 11, the voltage drop across the resistor 10 can be increased, and the vector V2 shown in FIG. 2 can be increased.

As a result, the voltage characteristic of the alternating current generator 1a changes from the solid line characteristic a to the chain line characteristic b, as shown in FIG. 5, and the reactive current can be shifted. Therefore, after this migration, the AC
By turning off Ba and restoring the contact point 11, the disconnection of the AC generator 1a can be completed. Here, in each embodiment, the changeover switch 9 and the contact 11 are not limited to mechanical ones, but may be constructed from a switching mechanism such as a semiconductor element.

As explained above, according to the parallel operation generator parallel disconnection control circuit according to the present invention, the AVR of the generator to be parallel operated is
Since the reactive current can be transferred by instantly increasing the input voltage of the ACB higher than that in the steady state, and then disconnecting the ACB, damage to the ACB etc. can be prevented.
Since the shifting operation can be performed by opening and closing the switching mechanism, great effects can be achieved, such as the ability to automate the uncoupling operation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining the parallel disconnection method in general parallel operation, FIGS. 2 and 3 are vector diagrams for explaining the parallel disconnection method explained in FIG. 1) and characteristic diagrams, FIG. 4 and FIG. 6 are circuit diagrams showing an embodiment of the parallel-operated generator parallel disconnection control circuit according to the present invention, and FIG. 5 is a characteristic diagram for explaining the parallel disconnect operation. 1a, 1b... AC generator, 2... Sensing voltage regulator θ regulator, 3... Voltage detection transformer, 4a
, 4b... Current transformer for cross current compensation, 5...
Cross current compensation resistor, 8a, 8b... Differential current transformer, 9... Changeover switch, 10... Resistor, 1]... Contact .

Claims (1)

[Claims] 1. First and second alternating current generators that operate in parallel;
a voltage detection transformer that detects the output voltage of the first alternator, an automatic voltage regulator that controls the first alternator, and a first voltage regulator that is connected between the voltage detection transformer and the automatic voltage regulator. 1 cross-current compensation resistor, a first cross-current compensation current transformer provided in the output circuit of the first alternator, and a second cross-current compensation resistor provided in the output circuit of the second alternator. The input side is connected to the compensation current transformer and the second cross current compensation current transformer, and the first
The output side of the first cross-current compensating resistor was connected to both ends of the second cross-current compensating resistor connected to the second alternator side in the same way as the first cross-current compensating resistor was connected to the first alternator side. The input side is connected to the second differential current transformer and the first cross current compensation current transformer, the first output side is connected to both ends of the first cross current compensation resistor, and the second output side is connected to both ends of the first cross current compensation resistor. a first differential current transformer whose side is differentially connected to a second output side of the second differential current transformer; A disconnection control circuit for a parallel-operated generator, comprising a change-over switch for switching between connection and disconnection, and switching a second output side of a second differential current transformer between differential connection and short-circuit. 2 The first and second alternators that operate in parallel, and the first
a voltage detection transformer that detects the output voltage of the first alternator, an automatic voltage regulator that controls the first alternator, and a first voltage regulator that is connected between the voltage detection transformer and the automatic voltage regulator. 1 cross-current compensation resistor, a first cross-current compensation current transformer provided in the output circuit of the first alternator, and a second cross-current compensation resistor provided in the output circuit of the second alternator. The input side is connected to the compensation current transformer and the second cross current compensation current transformer, and the first
The output side of the first cross-current compensating resistor was connected to both ends of the second cross-current compensating resistor connected to the second alternator side in the same way as the first cross-current compensating resistor was connected to the first alternator side. The input side is connected to the second differential current transformer and the first cross current compensation current transformer, the first output side is connected to both ends of the first cross current compensation resistor, and the second output side is connected to both ends of the first cross current compensation resistor. between the first differential current transformer whose side is differentially connected to the second output side of the second differential current transformer, the voltage detection transformer and the first cross-current compensation resistor; between the voltage detection transformer and the first differential current transformer; and a switch connected in parallel with a resistor.