JPH06225459A - Controlling method for power of non-utility generator facility - Google Patents

Abstract

PURPOSE:To exactly control power even when a reverse load-flow is recognized by immediately suppressing it, when a reverse load-flow is not recognized in a non-utility generator facility. CONSTITUTION:A reverse load-flow of a commercial power source 13 side is monitored by a sequencer 12 through a current transformer 8, a transformer 8 and a transducer 10, and when it becomes a predetermined value or more, the sequencer 12 outputs a signal SE to limit a fuel supply amount to an engine governor 4 thereby to suppress a reverse load-flow. When elimination of the reverse load-flow is recognized, it is transferred to a normal speed control. Even when the reverse load-flow is recognized, a fuel supply amount to the governor 4 is limited in response to the reverse load-flow, thereby preventing an increase in its frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control method in a power system in which a private power generator and a commercial power source are operated in parallel.

[0002]

2. Description of the Related Art In the industrial field that consumes a large amount of power,
For reasons such as stabilizing the power supply and reducing power costs, power is supplied to the load by purchasing electricity from the power company and operating in parallel with the private generator. Since no reverse power flow to the system is currently recognized, the engine governor speed control device is not used in order to prevent the reverse power flow phenomenon that occurs on the commercial power source side due to the sudden decrease in load during parallel operation.
It has already been proposed to directly control the fuel supply to the engine governor of the private power generator so as to instantaneously adjust the output of the private power generator (for example, JP-A-3-451).
See Japanese Patent Publication No. 28: Hereinafter, also referred to as a proposed device). The proposed device will be described in detail with reference to FIG.

In FIG. 2, 1 is a private power generation facility, 2 is a private power generator, 3 is an engine, 4 is an engine governor, 5
Is an engine governor speed controller (SPC), 6 is a potentiostat for setting the engine governor fuel limit, 7a is a power breaker, 7b is a generator breaker, 8 is a current transformer, and 9 is a voltage transformer. Reference numeral 10 is a received power transducer, 11 is a generated power transducer, 12 is a sequencer (SC), and 13 is a commercial power source. In other words, in the private power generation facility 1, the private power generator 2 that is operated in parallel with the commercial power supply 13 normally controls the speed of the engine governor 4 by the engine governor speed control device 5 so as to perform constant power generation output control or power reception via the engine 3. Constant power control is performed.

Under such an electric power system, it is assumed that the received electric power suddenly fluctuates and falls below a certain value.
In this case, the instrument current transformer 8 provided on the commercial power supply 13 side
Alternatively, the above-mentioned fluctuation is detected by the instrument transformer 9, and is sent to the received power transducer 10. The transducer 10 converts this detection signal into a received power signal and sends it to the sequencer 12. The sequencer 12 outputs a signal PS for speed control to the SPC 5 based on the deviation between the received power (actual value) and its set value, while
The control state is selected and distributed to a plurality of received power deviation ranges that are set in advance in correspondence with the fuel supply restriction amount to the engine 3.

That is, according to the output signal SL from the sequencer 12 relating to this distribution, one of the plurality of fuel supply limit setting potentiostats 6 provided in stages.
Selection signal S for limiting fuel supply
E is sent to the engine governor 4. As a result, the fuel supply valve (not shown) is closed, the fuel supply to the engine 3 is limited to the set value, and the generator output instantly decreases, and the private generator 2 is controlled based on this set value. . Then, only when the received power returns to a certain value or more and the actual generator output is lower than the target generator output by a predetermined amount, that is, when the fuel supply control amount by the speed control is equal to or less than the interrupt control amount. , Reset the interrupt control state to shift to speed control, and gradually recover to the target generator output.

[0006]

However, in the control as described above, the actual power reverse flow rate is not monitored, and the control is performed with the preset target value. At a grid connection point that is not established, there is a possibility that the reverse power flow may be too large to prevent the reverse power flow before the reverse power relay operates, and as a result, the receiving point breaker will be disconnected. On the contrary, if the reverse power flow is small, the output of the generator may be controlled more than necessary and the received power may be increased. Moreover, even when the restriction of fuel supply to the engine is lifted, the received power is increased more than necessary.

On the other hand, at the grid interconnection point where the reverse power flow is recognized, the above-mentioned reverse flow rate control is performed for the reverse power flow control when the grid and the private generator side are disconnected due to the grid side accident in the reverse power flow operation. When such control is performed, there is a problem that the frequency is unnecessarily lowered when the control amount is large, and conversely, when the control amount is small, extra fuel is used to raise the frequency more than necessary. Therefore, the object of the present invention is to immediately suppress the reverse flow when it is not observed,
It is to enable accurate power control even when reverse power flow is recognized.

[0008]

In order to solve such a problem, according to the first invention, the reverse flow rate of electric power is detected in a power system including a private power generator and a commercial power source and reverse flow is not recognized. However, the amount of fuel supplied to the engine governor is limited according to this reverse flow rate, and then it is detected that there is no reverse flow, and the output set value by the engine governor speed control device and the amount of fuel supply to the engine governor are limited. When it is detected that the generator output value becomes equal, the restriction on the amount of fuel supplied to the engine governor is released, and the speed control is performed.

Further, according to the second aspect of the invention, in a power system including a private power generator and a commercial power source, in which reverse power flow is recognized,
The reverse flow rate of electric power is always detected and stored in a predetermined cycle, and when the system and the private generator are disconnected due to an accident on the commercial power supply side, the reverse flow rate immediately before the disconnection is calculated, and the reverse flow rate is calculated. By limiting the amount of fuel supplied to the engine governor according to the amount, it is possible to prevent the frequency of the private generator from rising and to control the electric power without supplying extra fuel to the engine governor.

[0010]

[Function] When it is necessary to control the fuel supply instantaneously when the reverse power flow is not recognized, the reverse power flow rate of the power is controlled by the reverse power relay of the power reception point and the disconnection of the circuit breaker of the power reception point. Is detected after a short fixed time, and this is used as a target value, and when it is necessary to control the fuel supply instantaneously when reverse power flow is observed, the reverse power flow rate is fixed cycle (for example, 50 ms fixed cycle). ) Is detected and stored, the reverse flow rate immediately before the disconnection is instantaneously detected, and a fuel supply limit signal is directly sent to the engine governor by using this as a target value to limit the fuel to the required amount.

At this time, the control is performed in the form of giving priority to the speed control. However, even during the fuel supply control to the engine governor, the speed control for the engine governor of the private generator is working. Therefore, when the generator output set value by speed control becomes equal to the target value of the fuel supply control to the direct engine governor, the fuel supply control to the direct engine governor is reset, and thereafter, the speed control can be performed. , Appropriate power control will be performed.

[0012]

1 is a block diagram showing an embodiment of the present invention, in which a signal switcher 14 and a speed control output electric signal transducer 15 are added to those shown in FIG. Therefore, the differences from FIG. 2 will be mainly described below. (1) When a reverse flow occurs due to a sudden change in the received power when no reverse flow is observed. At this time, the reverse current flow rate is detected by the instrument current transformer 8 and the instrument transformer 9 provided on the commercial power source side, and is sent to the received power transducer 10. The received power transducer 10 converts the reverse flow rate into a received power signal and sends it to the sequencer 12.

The sequencer 12 operates to perform speed control based on the deviation between the received power signal and its set value, while the sequencer 12 calculates the fuel supply limit amount to the engine 3 equal to the reverse flow rate at that time. Then, the fuel supply limit setting electric signal SE of the calculation result is changed to the signal switch (L
OW selector) 14. The signal switch 14 compares the fuel supply limit setting electric signal SE with the speed control output electric signal SP. Then, here, the signal SE which is the lower value of the both is selected and given to the engine governor 4. As a result, the fuel supply valve (not shown) is closed, the fuel supply amount to the engine 3 is limited to the set amount, the generator output instantly decreases, and the private generator 2 is operated under this set value.

After that, the received power recovers to a certain value or more,
When the target generator output and the feedback signal FB of the speed control output electric signal SP become equal, the fuel supply limit setting electric signal SE is reset. As a result, the signal switching unit 14 selects the speed control output electric signal SP, and appropriate control, for example, constant power reception power control is performed by this speed control signal.

(2) When reverse power flow is recognized In this case as well, the reverse flow rate is detected using the instrument current transformer 8 and the instrument transformer 9 provided on the commercial power supply 13 side, and the transducer for receiving power is used. Send to 10. The received power transducer 10 converts this detection signal into a received power signal and sends it to the sequencer 12 in the same manner as above. At this time, the sequencer 12 constantly detects and stores this received power signal at a constant cycle. In such a case, a case where the grid and the private generator side are disconnected due to an accident on the commercial power source side and the frequency of the private generator rises will be described.

In this case, the sequencer 12 instantaneously calculates the reverse flow rate immediately before the parallel disconnection, and operates so as to perform speed control according to the deviation between this and the set value (reverse flow rate set value = 0). On the other hand, the fuel supply limit amount to the engine 3 which is equal to the reverse flow rate is also calculated by the sequencer 12, and the fuel supply limit setting electric signal SE corresponding to the calculation result is given to the signal switcher 14. The signal switcher 14 compares the fuel supply limit setting electric signal SE with the speed control output electric signal SP, selects the fuel supply limit setting electric signal SE which is the lower value, and sends it to the engine governor 4. To do.

As a result, the fuel supply valve (not shown) is closed, the fuel supply amount to the engine 3 is limited to the set value, and the frequency of the private generator 2 instantly drops to the rated frequency. After that, this fuel supply limit setting electric signal SE
And feedback signal FB of speed control output electric signal SP
When and become equal, the fuel supply limit setting electric signal S
Reset E. As a result, the signal switch 14 selects the speed control output electric signal SP, and thereafter, appropriate control by the speed control, for example, constant frequency control is performed.

[0018]

According to the present invention, the fuel supply to the engine is restricted by giving priority to the speed control.
In a power system in which a private power generator and a commercial power source are operated in parallel and reverse power flow is not recognized, there is an advantage that the power reverse power flow generated on the commercial power source side due to a sudden decrease in load can be immediately eliminated. As a result, it is possible to eliminate disconnection of the breaker for power reception due to reverse power flow. Further, when reverse power flow is recognized, it is possible to immediately eliminate an excessive power reverse power flow amount generated when the system and the private generator side are disconnected due to an accident on the system commercial power supply side. As a result, it is possible to prevent an increase in the frequency instantaneously and to eliminate an excessive fuel supply to the engine governor.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an already proposed device.

[Explanation of symbols]

1 ... Private power generation equipment, 2 ... Private power generator, 3 ... Engine, 4 ... Engine governor, 5 ... Engine governor speed control device, 6 ... Engine governor fuel limit setting potentiostat, 7a ... Power receiving breaker, 7b ... Power generation Breaker for machine, 8 ... Current transformer for instrument, 9 ... Transformer for instrument, 10 ... Transducer for received power, 11 ... Transducer for generated power, 12 ... Sequencer, 13 ... Commercial power supply, 14 ... Signal switch, 15 … Transducer for speed control output electric signal.

Claims (2)

[Claims] 1. A power system including a private generator and a commercial power source, in which reverse power flow is not recognized, detects a reverse flow rate of electric power, and limits a fuel supply amount to an engine governor according to the reverse flow rate. After that, if it is detected that there is no reverse power flow, and it is further detected that the output set value by the engine governor speed control device and the generator output value due to the fuel supply limit to the engine governor become equal, the engine governor is turned on. The method of controlling the electric power of the private power generation facility is characterized in that the restriction of the fuel supply amount is released and the speed control is performed. 2. A power system including a private power generator and a commercial power source, in which reverse power flow is recognized, the reverse power flow rate of electric power is constantly detected and stored in a predetermined cycle, and the system and the private power supply are used for an accident due to the commercial power supply side. When the power generator and the generator are disconnected, the reverse flow rate immediately before the parallel disconnection is calculated, and by limiting the fuel supply amount to the engine governor according to this reverse flow rate, the frequency rise of the private generator is prevented, A power control method for a private power generation facility, which controls power without supplying extra fuel to an engine governor.