JP4869198B2 - Distributed power system - Google Patents

Description

  The present invention relates to a distributed power supply system that performs grid interconnection or independent operation with a plurality of generators.

  As a conventional distributed power supply system that performs grid connection or independent operation, for example, a governor mechanism that has been mechanically operated is controlled by the engine control unit (ECU) to control the fuel injection amount to the engine. There is something that controls the number.

  In such a conventional distributed power supply system, when performing grid interconnection or independent operation with one generator, so-called droop control in which the rotation speed drops as the output increases during grid interconnection, Japanese Patent Application Laid-Open Publication No. 2004-259542 discloses a configuration in which so-called isochronous control is maintained to maintain a constant rotational speed.

  FIG. 4 is a graph for explaining the isochronous control, and is a graph showing the characteristics of the engine speed (rotational speed) with respect to the load. FIG. 5 is a graph for explaining the droop control, and is a graph showing the characteristics of the engine speed (rotational speed) with respect to the load.

  The isochronous control shown in FIG. 4 has an isochronous characteristic that maintains the rated output speed by increasing the fuel injection amount so as to achieve the rated output speed when the engine speed decreases due to the load. Thus, the rotation speed (rotation speed) is controlled. In this isochronous control, the engine speed of the rated output is maintained even if the load fluctuates during the self-sustaining operation, so that the operation can be performed at a stable frequency.

The droop control shown in FIG. 5 performs the rotation speed control (rotation speed) with a droop characteristic in which the engine rotation speed decreases at a constant droop rate as the load increases from the no-load state, as in the mechanical governor mechanism. Is. Here, the droop rate is a rate of droop indicated by (Na-Nb) / Nb (Na: rotational speed at no load, Nb: rotational speed at rated output (full load)). In this droop control, even if the frequency of the generator becomes unstable due to load fluctuations during grid connection, by entrusting the frequency characteristics to the system power supply with an overwhelmingly large power capacity compared to the generator, Also in this case, it is possible to operate at a stable frequency.
JP-A-4-344200

  However, in the above-described conventional technology, no consideration is given to rotation control of each generator when a plurality of generators that perform grid interconnection or independent operation are operated in parallel.

  Then, this invention aims at providing the distributed power supply system which can perform rotation control of each generator favorably when the generator which performs a grid connection or a self-sustained operation is operated in parallel with two or more. .

  In order to solve the above-described problem, the present invention provides a distributed power supply system that performs grid interconnection or independent operation with a plurality of generators. In grid interconnection, all the generators are controlled with a droop characteristic to control the rotational speed (droop control). During self-sustained operation, only one of the generators performs speed control (isochronous control) with isochronous characteristics, and the remaining power generators all perform speed control (droop control) with droop characteristics. A distributed power supply system is provided.

  According to the distributed power supply system of the present invention, at the time of grid connection, even if all the generators are droop controlled, it is possible to entrust the frequency characteristics to the grid power supply that has an overwhelmingly large power capacity compared to these generators. it can. Therefore, the behavior of the output frequency can be stabilized. In addition, during independent operation, only one of the generators is controlled isochronously, so that the frequency characteristics can be controlled by one generator that performs this isochronous control. In a state where all the droop control is performed, it is possible to contribute to stabilization of the behavior of the output frequency.

  In the distributed power supply system according to the present invention, different unique numbers are set in advance for the respective generators, the numbers of the generators supplying power to each other are recognized, and the isochronous characteristics at the time of independent operation are determined. The specific mode which makes the generator which performs rotation speed control by the generator of the minimum number or the maximum number can be illustrated. By doing so, it is possible to easily identify the generator that performs the isochronous control during the autonomous operation.

  In such a configuration, it is preferable to assign a zero number or a number larger than the number of any generator to be set to the system power supply, and to recognize the generator number, the system power supply is a virtual generator. By doing so, it becomes possible to reliably perform droop control of all the generators during grid connection. Further, in this configuration, the generator that is supplying power is recognized based on an open / close signal of a circuit breaker arranged between each generator and the power supply path, and whether or not the virtual generator is supplied with power is It can be recognized based on the switching signal of the power receiving breaker from the system power supply. Thereby, it can be recognized reliably whether each said generator is supplying electric power.

  As described above, according to the present invention, there is provided a distributed power supply system that can satisfactorily perform rotation control of each generator when a plurality of generators that perform grid interconnection or independent operation are operated in parallel. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a distributed power supply system according to the present invention. A distributed power supply system 100 shown in FIG. 1 includes a plurality of distributed power supply devices D1 to Dn (n is an integer of 2 or more) and a control device 10.

  In this distributed power supply system 100, the system power supply 30 that connects the system power supply 30 and the plurality of distributed power supply devices D <b> 1 to Dn in parallel by performing operation control of the control device 10 and the system operation is separated from the system power supply 30. In this state, any one of the independent operation in which power is supplied from the plurality of distributed power supply devices D1 to Dn is performed.

  FIG. 2 is a block diagram showing a schematic configuration of the distributed power supply devices D1 to Dn and the control device 10 shown in FIG. Each of the distributed power supply devices D1 to Dn includes an engine E1 to En, an engine control unit F1 to Fn, and a generator G1 to Gn, respectively, and is connected to the control device 10. Each engine control unit F1 to Fn controls the rotational speed (rotational speed) of the engines E1 to En by controlling the fuel injection amount to the engines E1 to En under the instruction of the control device 10. ing.

  The control device 10 includes a processing unit 11 such as a CPU (Central Processing Unit) and a storage unit 12 such as a ROM (Read Only Memory) and a RAM (Random Access Memory). By reading the program from the storage unit 12 and executing the read control program, operation control of each of the distributed power supply devices D1 to Dn is performed.

  The control device 10 is configured to instruct the distributed power supply devices D1 to Dn to switch between isochronous control and droop control for the engines E1 to En.

  Specifically, when the control device 10 issues a switching command for isochronous control to each of the distributed power supply devices D1 to Dn, the control device 10 transmits a switching signal for performing isochronous control together with information on a predetermined rated rotational speed. ing. In addition, when the control device 10 issues a droop control switching command to each of the distributed power supply device units D1 to Dn, the control device 10 transmits a switching signal for performing the droop control together with information on the predetermined rated rotation speed and the droop rate. It has become. Examples of the rated rotational speed include 1500 revolutions / minute and 3000 revolutions / minute at a generator frequency of 50 Hz, and 1600 revolutions / minute and 3200 revolutions / minute at a generator frequency of 60 Hz. Examples of the droop rate include over 0% and about 6% or less (typically about 3%).

  In each of the distributed power supply devices D1 to Dn, switching of isochronous control is instructed by the control device 10, and a switching signal for performing isochronous control is transmitted from the control device 10 together with information on the rated rotation speed (for example, 3000 times / minute: 50 Hz). When transmitted, the rotational speed is controlled with the isochronous characteristic of the rated rotational speed (see FIG. 4). Further, in each of the distributed power supply devices D1 to Dn, switching of droop control is instructed by the control device 10, and a switching signal for performing the droop control is transmitted from the control device 10 to a rated rotational speed (for example, 3000 times / minute: 50 Hz) and When it is transmitted together with information on the droop rate (for example, 3%), the rotational speed is controlled by the rated speed and the droop characteristic of the droop rate (see FIG. 5).

  And the control apparatus 10 is provided with the grid connection mode and the independent operation mode, and while performing the grid connection mode at the time of grid connection, it performs the independent operation mode at the time of independent operation.

  FIG. 3 is a diagram conceptually showing an operation state of the distributed power supply system 100 shown in FIG. 1, FIG. 3 (a) shows an operation state at the time of grid connection, and FIG. It shows the operating state during independent operation. In FIG. 3, the controller 10 is not shown.

  As shown in FIG. 3A, the control device 10 sets all the generators (here, the generators G1 to Gn) in the distributed power supply device that is supplying power among the plurality of distributed power supply devices D1 to Dn at the time of grid connection. A grid interconnection mode in which the rotational speed is controlled by the droop characteristic is executed, and as shown in FIG. 3B, one of the plurality of distributed power supply devices D1 to Dn that is supplying power during the independent operation. The generators (here, the generators G2 to Gn) of the remaining distributed power supply units that perform rotation speed control with isochronous characteristics only in the generators of the single distributed power supply unit (here, the generator G1) and supply power It is configured to execute a self-sustaining operation mode in which the rotational speed control is performed with the droop characteristic.

  According to the distributed power supply system 100, when the system is connected, the frequency characteristics can be entrusted to the system power supply 30 that has an overwhelmingly larger power capacity than the generators G1 to Gn. Even if the frequency of ~ Gn fluctuates, it becomes possible to operate at a stable output frequency, and at the time of self-sustained operation, the frequency characteristic is controlled by one generator G1 that performs isochronous control. It is possible to stabilize the behavior of the output frequency like the system power supply 30 with one generator G1.

  By the way, it is conceivable to control the rotational speed of all the generators that are supplying power during the independent operation with isochronous characteristics. In this isochronous control, as shown in FIG. Because it is constant regardless of fluctuations, isochronous control of all generators that are supplying power during self-sustained operation tends to cause a situation in which the controller 10 malfunctions with two or more generators and the engine speed is not determined. Therefore, troubles such as engine runaway may occur.

  On the other hand, in the droop control, since the target value of the engine speed with respect to the load is uniquely determined, the engine speed can be converged to the target value. For example, as shown in FIG. 5, when the droop rate is 3%, the rotation speed of the load at 50% of the capacity range is 3045 rotation speeds reduced by 1.5% from the rotation speed of 3090 rotations / minute when there is no load. Per minute. Therefore, when performing isochronous control for only one generator that is supplying power and performing droop control for all remaining generators that are supplying power, malfunction of the control device 10 while stabilizing the behavior of the output frequency. Can be effectively prevented, and engine runaway can be avoided.

  From such a viewpoint, in the distributed power supply system 100 according to the embodiment of the present invention, only the generator G1 in the single distributed power supply device D1 that is supplying power during the self-sustained operation performs the rotational speed control with isochronous characteristics and is supplying power. The generators G2 to Gn in the remaining distributed power supply devices D2 to Dn all perform rotational speed control with droop characteristics.

  In the present embodiment, different unique numbers (here, Nos. 1 to n) are preset (stored in the storage unit 12 here) for each of the generators G1 to Gn. And the control apparatus 10 recognizes the number of the generator which is supplying electric power mutually between each generator G1-Gn, and is connected to all the generators (here No. 1-n of an electric power supply) at the time of grid connection. The number of generators G1 to Gn) is controlled by the droop characteristic, and at the time of self-sustained operation, only the generator with the smallest or largest number during power supply (here, the first generator G1) is controlled with the isochronous characteristic. The remaining generators (in this case, the generators G2 to Gn of Nos. 2 to n) that are supplying power are all controlled to rotate at the droop characteristic. By doing so, it is possible to easily identify the generator that performs the rotational speed control with the isochronous characteristic during the autonomous operation.

  Moreover, in this Embodiment, the control apparatus 10 is a number (for example, n + 1 number) (here 0 number) larger than the zero number (0 number) or any number of each generator G1-Gn set beforehand. ) Is applied to the system power supply 30, and the system power supply 30 is configured as a virtual generator when the numbers of the generators G1 to Gn are recognized.

  That is, at the time of grid connection, the control device 10 has a grid power supply to which a virtual generator is assigned a zero number (0) or a number (for example, n + 1) that is larger than any of the generators G1 to Gn. Droop control is performed on all generators connected in parallel with the power supply 30 (here, the generators G1 to Gn of No. 1 to n), and power is being supplied in a state of being disconnected from the system power supply 30 during independent operation. The remaining generators (here, Nos. 2 to n generators G2 to Gn) are all drooped by isochronous control of only the generator with the smallest or largest number (here, No. 1 generator G1). It comes to control.

  In the distributed power supply system 100 having such a configuration, the number 0 or n + 1 (here, No. 0) is assigned as a virtual generator while reliably performing droop control on all the generators G1 to Gn that are supplying power during grid connection. It is possible to stabilize the behavior of the output frequency with the system power supply 30 to which is provided.

  Moreover, in the distributed power supply system 100 according to the present embodiment, as shown in FIGS. 1 and 2, the circuit breakers 52G1 to 52Gn of the generators G1 to Gn from the power receiving circuit breaker 52R from the system power supply 30 (FIG. 2), the power supply path P is provided until it reaches immediately before.

  By the way, each generator G1-Gn has the state which cannot supply electric power like the case of the driving | running | working initial state etc., even if it is a driving | running state. For this reason, in the distributed power supply system 100, the circuit breakers 52G1 to 52Gn disposed between the generators G1 to Gn and the power supply path P are opened in a state in which the generators G1 to Gn cannot supply power, and When the machines G1 to Gn can supply power, the circuit breakers 52G1 to 52Gn can be closed. In the distributed power supply system 100, whether or not power is supplied from the system power supply 30 to the load side is determined by opening and closing a power receiving circuit breaker 52R from the system power supply 30.

  From this viewpoint, the control device 10 supplies power to each of the generators G1 to Gn based on an open / close signal corresponding to the open / close state of the circuit breakers 52G1 to 52Gn disposed between the generators G1 to Gn and the power supply path P. It is configured to recognize whether the system power supply 30 as a virtual generator is supplying power based on an open / close signal corresponding to the open / close state of the power receiving circuit breaker 52R from the system power supply 30. Has been.

  Specifically, when the control device 10 recognizes that the circuit breakers 52G1 to 52Gn are closed by the switching signals from the circuit breakers 52G1 to 52Gn, the power receiving circuit breaker is received from the power receiving circuit breaker 52R. When it is recognized that 52R is open, the autonomous operation mode is executed. In addition, when the control device 10 recognizes that the circuit breakers 52G1 to 52Gn are closed by the switching signals from the circuit breakers 52G1 to 52Gn, the power receiving circuit breaker 52R is closed by the switching signal from the power receiving circuit breaker 52R. When it is recognized that the system is connected, the grid connection mode is executed.

  As described above, the control device 10 obtains an opening / closing signal from the circuit breakers 52G1 to 52Gn immediately before the generators G1 to Gn and the power receiving circuit breaker 52R immediately after the system power supply 30 to thereby generate the generators G1 to Gn and the systems. The autonomous operation mode or the grid interconnection mode can be executed in a state where it is surely recognized whether or not the power supply 30 is supplying power.

1 is a schematic configuration diagram showing an embodiment of a distributed power supply system according to the present invention. It is a block diagram which shows schematic structure of the distributed power supply device and control apparatus which are shown in FIG. It is a conceptual diagram which shows the operation state of the distributed power supply system shown in FIG. 1, Comprising: FIG. (A) is a figure which shows the operation state at the time of grid connection, FIG. (B) shows the operation state at the time of independent operation. FIG. It is a figure for demonstrating isochronous control, Comprising: It is a graph which shows the characteristic of the engine speed (rotation speed) with respect to load. It is a figure for demonstrating droop control, Comprising: It is a graph which shows the characteristic of the engine speed (rotation speed) with respect to load.

Explanation of symbols

30 System power supply 52G1-52Gn Circuit breaker 52R Power receiving circuit breaker 100 Distributed power supply system G1-Gn Multiple generators

Claims (4)

In a distributed power system that performs grid interconnection or independent operation with multiple generators,
During grid connection, all generators are controlled with the droop characteristics, and during independent operation, only one of the generators is controlled with the isochronous characteristics, and the remaining generators are all with the droop characteristics. A distributed power supply system characterized by performing rotation speed control. The distributed power supply system according to claim 1,
A unique number is set in advance for each of the generators, the number of the generators supplying power to each other is recognized between the generators, and the number of revolutions is controlled by isochronous characteristics during independent operation. Is a generator having a minimum number or a maximum number. The distributed power supply system according to claim 2,
A distributed power supply system characterized in that a zero number or a number larger than any set generator number is assigned to a system power supply, and when the generator number is recognized, the system power supply is a virtual generator. The distributed power supply system according to claim 3,
Recognizing a power supply generator based on an open / close signal of a circuit breaker arranged between each of the power generators and a power supply path, and receiving power from the system power supply to determine whether or not the virtual generator is powered A distributed power supply system that recognizes based on a circuit breaker switching signal.

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