JPH04372527A - Automatic controller of phase-advance capacitor - Google Patents

Abstract

PURPOSE:To conduct a safe power factor improvement by selecting and closing phase-advancing capacitors so that the capacitors are within the possible output range of a private power generator according to the result of detection of whether the operating state of a commercial power supply and private power generator is a parallel operation or individual operation of any one of them and whether the point of measurement of a power factor is a receiving point or the output point of the private power generator. CONSTITUTION:The parallel operation of a commercial power supply 3 and private power generator 1 or the individual operation of any one of them is conducted by circuit breakers 2 and 6 and switch 5. With a bus L, a power load 7 composed of a plurality of power loads #l-#n and a phase-advance capacitor group 8 composed of a plurality of phase-advance capacitors are connected via the switch, respectively. The automatic controller 10 of the phase-advance capacitors automatically selects and closes the phase-advance capacitors to improve a power factor so that the capacitors are within the possible output range of the private power generator according to various data such as whether an operating state is 'the parallel operation of the commercial power supply 3 and private power generator 1 or the individual operation of any one of them, whether the point of measurement of a power factor is a receiving point or the output point of the private power generator and whether the load is high or low. Thus, the power factor is improved safely and power rates are reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic control system for a phase advance capacitor in a customer having a power generation facility.

0002

[Prior Art] Conventionally, an operator has to turn on and off a phase-advancing capacitor based on changes in the customer's operating conditions, or detect the power factor and automatically adjust it to the desired power factor. Was.

0003

[Problems to be Solved by the Invention] However, in the past, the turning on and off of phase advance capacitors to improve the power factor of consumers who have power generation equipment that operates in parallel with electric power companies or operates independently is based on human judgment. This is done manually, and it is necessary to operate it in response to changes in operating conditions, but there is a problem that if the judgment is wrong, the power generation equipment becomes abnormal or the electricity bill becomes relatively high.

The present invention has been made to solve these problems, and provides an automatic control device for phase advance capacitors that can automatically protect power generation equipment and improve the power factor. The purpose is to

[0005]

[Means for Solving the Problems] An automatic control device for a phase advance capacitor according to one aspect of the present invention detects a parallel operation state between a commercial power source and a consumer generator, and also selects power factor control of the generator. means for detecting whether the point is set at the output point or the power receiving point of the generator, and when the power factor control selection point of the generator is in a parallel operation state and the power factor control selection point of the generator is set at the power receiving point, and means for inserting a phase advance capacitor so that the output of the generator is within a possible output range. In an automatic control device for a phase advance capacitor according to another aspect of the present invention, the capacity of the phase advance capacitor to be input is set in advance.

The automatic control device for a phase advance capacitor according to another aspect of the present invention further provides a load reactive power and a generator reactive power when the power factor control selection point of the generator is set at the output point. It has means for inserting a phase advancing capacitor with a capacity corresponding to the difference between the two. The automatic control device for a phase advance capacitor according to another aspect of the present invention further includes a means for detecting an islanding state by a consumer's generator, and a means for detecting an islanding state by a generator of a consumer, and a means for controlling the output of the generator to be within a possible output range in the islanding state. and means for inserting a phase advance capacitor into the phase advance capacitor. The automatic control device for a phase advance capacitor according to another aspect of the present invention further includes means for detecting an operating state in which only electric power from a commercial power source is being supplied to a load;
and means for turning on a phase advance capacitor having a capacity corresponding to the received power when the power supply is in operation using a commercial power source.

[0007]

[Operation] In one embodiment of the present invention, when the power factor control selection point of the generator is set at the power receiving point in a parallel operation state of the commercial power source and the generator of the consumer means,
A phase advance capacitor is inserted so that the output of the generator is within the possible output range. In another aspect of the present invention, the capacitance of the phase advancing capacitor introduced above is set in advance.

In another aspect of the present invention, when the power factor control selection point of the generator is set at the output point, the capacity progresses in response to the difference between the load reactive power and the generator reactive power. The phase capacitor is turned on. In another aspect of the present invention, a phase advance capacitor is inserted so that the output of the generator is within the possible output range during the individual operation state. In another aspect of the present invention, when operating with commercial power,
A phase advance capacitor with a capacity corresponding to the received power is inserted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an automatic power factor adjustment device and related equipment according to an embodiment of the present invention. In the figure, 1 is a consumer-side generator, and 2 is a generator circuit breaker. 3 is a commercial power supply, and 4 is a transaction transformer for receiving the supply of commercial power by contracting with an electric power company. 5 is a switch, and 6 is a power receiving circuit breaker. 7 is the power load;
8 is a phase advance capacitor group. 10 is a phase advance capacitor automatic control device.

This phase advance capacitor automatic control device 10 has inputs indicating the operating status of the consumer side, such as "power receiving circuit breaker on" and "
"Generation circuit breaker on", "Generated power", "Received power" (or reverse power), "Generated power" and "Load power" are input, and "Load reactive power" and "Generator supplied" are input. Enter the amount of reactive power to be used. "Load reactive power amount" can be measured by a reactive wattmeter or load power amount (load power amount = generated power amount + received power amount, load power amount = generated power amount -
This can be determined by estimation based on the amount of power transmitted (reverse transmission energy). In addition to the above-mentioned data, the phase advance capacitor automatic control device 10 also contains a message indicating whether the power factor control of the generator is controlling the power factor of the power receiving point or the power factor control of the output point of the generator. The generator power factor control selection point is the power receiving point,""power factor control automatic input" indicates whether or not to automatically control the power factor, the generator's possible output curve, the capacity of the phase advance capacitor, etc. are input. Based on the information, a phase-advancing capacitor is automatically added to the reactive power corresponding to the reactive power of the load so that the power factor at the receiving point approaches 1.0 within the generator's possible output curve. Outputs the capacitor closing and tripping signals.

FIG. 2 shows a logic circuit for grasping the operating state of the phase advance capacitor automatic control device. In the figure, 21 to 29 are AND circuits, and 30 to 33 are NOT circuits.

Next, turning on and turning off the phase advance capacitor will be explained with reference to FIGS. 1 and 2 according to the operating state of the consumer. (1) Generator independent operating state: In this operating state, the power receiving circuit breaker 6 is turned off, and the "power receiving circuit breaker on" shown in Fig. 2 is activated.
The rest are in the set state, the AND circuits 24 and 28 grasp the generator independent operation state, and the control means 42 turns on the preset phase advance capacitor 8. This operating state is unrelated to the electric power company, and the load 7 determines the reactive power. Therefore, the capacitors of the phase advance capacitor group 8 are inserted so that the generator 1 falls within the possible output curve. FIG. 3 is a vector diagram showing the relationship between active power and reactive power. The reactive power of the load is adjusted by the reactive power of the generator and the amount input by the phase advance capacitor, and the power factor is kept at a constant value. The magnitude of the reactive power of this generator is determined by the generator's possible output curve. FIG. 4 is a diagram showing the possible output curve of the generator. For example, set the output point of the generator to 0.8p. u. If the power factor is controlled by 0.6p. u. Since the reactive power can only be output up to 100%, it may be necessary to insert a phase advance capacitor to improve the power factor. If there is a possibility that the possible output curve of the generator will be exceeded, it is necessary to insert the capacitors of the phase advance capacitor group 8 to protect the generator.

(2) Parallel operation with commercial power supply: Both the power receiving circuit breaker 6 and the generator circuit breaker 2 are closed. a) When the power factor control of the generator is set as the output point: When the power factor control selection point of the generator is set as the output point of the generator, in Figure 3, the “generator power factor control selection point is the receiving point ” are in the set state, NOT circuit 30, AND circuits 22, 2
7 indicates the operating state in which parallel operation is performed and the power factor control selection point of the generator is the output point. In this case, the control means 41 turns on the capacitors of the phase advance capacitor group 8 that correspond to the difference between the load reactive power and the generator reactive power. Here, the load reactive power is determined by the following formula. Load reactive power = Load power x Expected coefficient Load power = Generated power + Received power (In the case of reverse transmission, the received power will be a negative value)

b) When the power factor control of the generator is set to the power receiving point: When the power factor control selection point of the generator is set to the power receiving point, everything is in the set state in FIG. 2, and the knot circuit 30 , AND circuits 23, 21, and 26 grasp the operating state in which parallel operation is performed and the power factor control selection point of the generator is the power receiving point. In this case, there is a risk that the possible output curve of the generator will be exceeded, so the control means 40 turns on the capacitors of the phase advance capacitor group 8 to protect the generator.

(3) In the case of power purchase only: Operation is performed with the generator circuit breaker 2 disconnected and the power reception circuit breaker 6 closed. In FIG. 2, "power receiving circuit breaker ON" and "power factor control automatic ON" are set, and AND circuits 25, 2
9 indicates that the power is being purchased. in this case,
The control means 43 turns on the capacitors of the phase advance capacitor group 8 according to the received power, and the power factor is controlled. (4) Manual operation: In this case, since "power factor control auto-on" is not set, the knot circuit 33 identifies the manual operation state.

Table 1 is an example summarizing the closing states of the phase advance capacitor group 8 in each of the above operating states. This example shows a case where the phase advance capacitor group 8 has four feeders.

[Table 1] SC: Phase advance capacitor input hysteresis time: △ minutes (arbitrary setting) □: Arbitrary setting (power) value The ○ mark above indicates the corresponding phase advance capacitor to be input.
In addition, hysteresis due to time shall be provided when the phase advancing capacitor is turned on. In addition, as mentioned above, when the output point is selected in parallel operation, a phase advance capacitor corresponding to the difference between the load reactive power and the generator reactive power is input and is not fixed, so the phase advance capacitor to be input is as shown in Table 1. is not shown.

[0017]

[Effects of the Invention] As described above, according to the present invention, the operating state of the consumer is ascertained and a phase advance capacitor with a capacity corresponding to the operating state is automatically turned on, so that the generator is within the possible output curve. It is extremely effective in protecting the generator. Furthermore, since the power factor is improved, it is also effective in reducing electricity charges.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an automatic control device for a phase advance capacitor and related equipment according to an embodiment of the present invention.

FIG. 2 is a block diagram showing details of the automatic control device for the phase advance capacitor shown in FIG. 1;

FIG. 3 is a vector diagram showing the relationship between active power and reactive power of a load.

FIG. 4 is a diagram showing a possible output curve of a generator.

[Explanation of symbols]

1 Generator 2　Generator circuit breaker 3 Commercial power supply 6 Power receiving circuit breaker 7 Power load 8 Phase advance capacitor group 10　Phase advance capacitor automatic control device

Claims (5)

[Claims] [Claim 1] Detecting a parallel operation state between a commercial power source and a consumer's generator, and detecting whether the power factor control selection point of the generator is set at the output point or the power receiving point of the generator. When the power factor control selection point of the generator is set at the power receiving point, a phase advance capacitor is inserted so that the output of the generator is within the possible output range. An automatic control device for a phase advance capacitor having means. 2. The automatic control device for a phase advance capacitor according to claim 1, wherein the capacity of the phase advance capacitor to be input is set in advance. Claim 3: When the power factor control selection point of the generator is set to the output point, the difference between the load reactive power and the generator reactive power is handled while supplying power from the commercial power source to the load. 3. The automatic control device for a phase advance capacitor according to claim 2, further comprising means for inputting a phase advance capacitor having a capacity of 1. 4. A claim comprising means for detecting an islanding state of a consumer's generator, and means for inserting a phase advance capacitor so that the output of the generator falls within a possible output range when in the islanding state. 3. Automatic control device for a phase advance capacitor according to item 3. 5. Means for detecting an operating state in which only electric power from a commercial power source is being supplied to a load; and means for turning on a phase advancing capacitor having a capacity corresponding to the received power when the operating state is based on the commercial power source. 5. The automatic control device for a phase advance capacitor according to claim 4.