JP2012100478A - Control method of power generation system and controller of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the decline of the frequency of output power when connected to a power load during an autonomous operation while preventing the decline of power generation efficiency.SOLUTION: A controller of a power generation system (1) includes a secondary excitation induction generator (2), a driving source (3), a first power converter (11), a second power converter (12), a power storage device (5), and changeover switches (21, 22, 23). Regarding the autonomous operation of driving the driving source as an engine (3) at a target rotating speed and supplying power from the power storage device (5) without receiving power supply from the outside (4) and thereby freely supplying the output power of a desired target frequency to a power load (7), a standby operation process of driving the engine (3) at a non-load time rotating speed higher than the target rotating speed in a non-load state and controlling the output power to the target frequency is executed, and a load connecting process of connecting the power load (7) is executed thereafter.

Description

  The present invention provides a secondary excitation induction generator having a stator having a primary winding and a rotor having a secondary winding, a drive source for driving the rotor, and an AC side connected to the primary winding. The first power converter, the second power converter whose AC side is connected to the secondary winding, and the DC that connects the DC side of the first power converter and the DC side of the second power converter The present invention relates to a control method for a power generation system including a power storage device connected to a unit, and a changeover switch that selectively connects the primary winding and a power load, and a control device therefor.

  Conventionally, secondary excitation induction that can change the frequency of the output power with respect to the shaft input rotation speed, such as wind power generation and pumped-storage power generation, which changes the shaft input rotation speed input to the generator A power generation system that can control the frequency of output power to a target frequency (50 [Hz] or 60 [Hz]) by using it together with a generator has been proposed (see, for example, Patent Document 1). This Patent Document 1 only discloses a power generation system that uses a secondary excitation induction generator for wind power generation and pumped storage power generation. For example, as a drive source for driving a rotor of a secondary excitation induction generator If the engine can be used, the rotation speed of the engine can be freely selected while the frequency of the output power can be controlled to the target frequency (50 [Hz] or 60 [Hz]), and the power generation efficiency can be improved.

  On the other hand, conventionally, an engine cogeneration system using a synchronous generator as a generator is known as a power generation system using an engine as a drive source of the generator.

JP 2009-27766 A

  In an engine cogeneration system using a synchronous generator, the frequency of output power is affected by the engine rotation speed of the drive source, so the gas engine that is the drive source is operated at a constant rotation speed synchronized with the system frequency of the power system. There is a need to. For example, in an area where the system frequency is 60 Hz, operation is performed at discrete rotational speeds such as 900 rpm (15 Hz), 1200 rpm (20 Hz), and 1800 rpm (30 Hz), which is an integer of 60 Hz, according to the number of poles of the synchronous generator. There is a need to. Therefore, in the engine cogeneration system, the engine speed for outputting the target frequency (50 [Hz] or 60 [Hz]) by the synchronous generator is restricted to a constant speed, so the output is reduced from the rating. In doing so, the power generation efficiency is greatly reduced.

In addition, when using an engine cogeneration system as a power generation system, it is important to be able to operate independently as an emergency power source that can supply power to a power load even when power is not supplied from the power system. is there. In autonomous operation, in order to supply output power of a desired target frequency to the power load, the engine is driven at a predetermined target rotation speed, and then connected to the power load, and the output power of the target frequency is connected to the power load. Supply.
Here, when the engine cogeneration system is connected to an electric power load, the load on the engine increases, so the rotational speed of the engine temporarily decreases. And there existed a problem that the frequency of output electric power fell with such a fall of an engine speed.

  The above problem will be described with reference to FIGS. FIG. 7 is a graph showing fluctuations in the rotational speed of a gas engine when a power generation system in a self-sustaining operation state is connected to an electric power load in a conventional power generation system using a generator as a synchronous generator.

  In FIG. 7A, the power generation system is not connected to an electric power load and is in a so-called no-load state in which a self-sustaining operation is performed. In (A), the gas engine is driven at a target rotation speed (for example, a rated rotation speed) of 1200 rpm. When the power generation system is connected to the power load in (B), the engine rotation speed temporarily decreases to 1050 rpm due to an increase in the engine load. After that, after a slight increase and decrease, it eventually converges to the target rotational speed (C).

  FIG. 8 is a graph showing fluctuations in the frequency of the output power when the engine speed fluctuates as shown in FIG. 7 in the power generation system using the generator as a synchronous generator.

  The frequency of the output power of the power generation system is affected by the rotational speed of the engine that drives the generator. Here, as shown in FIG. 8, in (A) before the power load connection, since the gas engine is stably driven at the target rotational speed of 1200 rpm, the output power is also stable at the target frequency (60 Hz). Can be supplied. However, when a power load is connected in (B) and the engine speed decreases due to an increase in the load on the engine, the frequency of the output power also decreases accordingly. Thereafter, when the rotational speed of the gas engine fluctuates, the frequency of the output power also fluctuates (C).

  Since the frequency of the output power fluctuates greatly as described above is not preferable for the connected power load, the upper limit of the size of the power load that can be connected to the power generation system (hereinafter referred to as “load input amount”) is limited. As a result, the power load connected during the self-sustaining operation cannot be increased, and the value as an emergency power source is reduced. On the other hand, in order to be able to connect to a large electric power load, the power generation system must have an excessive capacity sufficient to cover the electric power load. Become.

  The present invention has been made in view of the above problems, and its object is to prevent the frequency of output power from being lowered when connected to a power load during self-sustained operation while preventing reduction in power generation efficiency. It is in providing a control method and a control device of a power generation system that can be used.

  A first characteristic configuration of a control method of a power generation system according to the present invention for achieving the above object is a secondary excitation induction generator having a stator including a primary winding and a rotor including a secondary winding; A drive source for driving the rotor; a first power converter having an AC side connected to the primary winding; a second power converter having an AC side connected to the secondary winding; and the first power conversion. A power generation device comprising: a power storage device connected to a DC unit that connects a DC side of the power supply and a DC side of the second power converter; and a changeover switch that selectively connects the primary winding and a power load. A system control method, wherein an engine having an adjustable rotation speed is provided as the drive source, and the engine is driven at a predetermined target rotation speed without being supplied with electric power from an external power system. , By supplying power from the power storage device The self-sustained operation for supplying output power of a desired target frequency to the power load, the engine is set to the target in a no-load state in which the changeover switch is open and the primary winding is not connected to the power load. Drive at a no-load rotation speed that is faster than the rotation speed, and execute a standby operation step of controlling the output power of the primary winding to the output power of the target frequency, and then close the changeover switch to the primary A load connecting step of connecting a winding to the power load is performed.

  In order to achieve the above object, a first characteristic configuration of a control device for a power generation system according to the present invention is a secondary excitation induction generator having a stator having a primary winding and a rotor having a secondary winding. A drive source for driving the rotor, a first power converter whose AC side is connected to the primary winding, a second power converter whose AC side is connected to the secondary winding, and the first A power storage device connected to a DC unit that connects the DC side of the power converter and the DC side of the second power converter; and a selector switch that selectively connects the primary winding and the power load. The power generation system control device includes an engine having an adjustable rotation speed as the drive source, drives the engine at a predetermined target rotation speed, and receives power from an external power system. Without power supply from the power storage device. The self-sustained operation control unit that performs the self-sustained operation for supplying output power of a desired target frequency to the power load is in a no-load state in which the changeover switch is open and the primary winding is not connected to the power load. A standby operation control unit for driving the engine at a no-load rotational speed faster than the target rotational speed and executing a standby operation step of controlling the output power of the primary winding to the output power of the target frequency; And a load connection control unit that executes a load connection step of connecting the primary winding to the power load with the changeover switch in a closed state.

According to the above characteristic configuration, since the engine having a freely adjustable rotation speed is provided as a drive source, a secondary excitation induction generator is used, and a system using the engine as the drive source of the generator is used. Can do. Therefore, since the frequency of the output power can be changed with respect to the shaft input rotation speed of the secondary excitation induction generator by controlling the operation of the second power converter, the frequency of the output power is set to the target frequency (50 While controlling at [Hz] or 60 [Hz]), the rotational speed of the engine can be freely selected. As a result, the power generation efficiency can be improved.
Further, according to the above characteristic configuration, in the self-supporting operation, the load connection process is performed after the standby operation process. Therefore, when the load connection process for connecting the primary winding to the power load is performed, the engine rotation is performed. Set the speed to a no-load rotation speed that is faster than the target rotation speed (Note that because the generator uses a secondary excitation induction generator, the frequency of the output power can be changed relative to the shaft input rotation speed. Even if the engine speed is set to the no-load speed, the frequency of the output power can be controlled to a predetermined target frequency). And by setting the engine rotation speed to the no-load rotation speed and storing the kinetic energy in the engine flywheel, a significant decrease in the engine rotation speed when the power load is connected is suppressed, and the frequency of the output power is reduced. Variation can be suppressed.
That is, according to the above characteristic configuration, it is possible to suppress a decrease in the frequency of the output power when connected to the power load during the self-sustained operation while utilizing the characteristics of the secondary excitation induction generator. And suppression of the fall of this frequency contributes to making the frequency of output electric power converge the target frequency in a short time. As a result, it is possible to prevent a decrease in the frequency of the output power while preventing a decrease in power generation efficiency, so that it is possible to connect to a larger power load, and the value as an emergency power supply is improved.

  A second characteristic configuration of the control method of the power generation system according to the present invention is the first characteristic configuration of the control method, wherein the no-load rotation speed is the maximum rotation speed of the engine or the switching from the no-load state. A point that is set to one of the rotation speeds that are higher than the rotation speed and lower than the maximum rotation speed at which the decrease in the frequency of the output power when the switch is closed and connected to the power load can be kept within the target range. It is in.

  Further, a second characteristic configuration of the control device of the power generation system according to the present invention is the first characteristic configuration of the control device, wherein the standby operation control unit determines the no-load rotation speed as the maximum rotation speed of the engine, Or, the rotation speed is not less than the maximum rotation speed and not more than the maximum rotation speed at which the decrease in the frequency of the output power when the changeover switch is connected to the power load with the changeover switch closed from the no-load state. In this point, the standby operation process is performed by setting the value to any one of the above.

  According to said characteristic structure, the fall of the frequency of the output electric power at the time of electric power load connection can be suppressed considering the engine rotational speed at the time of a no-load state (at the time of a standby driving | running process) based on the mechanical restrictions of an engine. Alternatively, it is possible to set the rotation speed at which the frequency reduction of the output power when the power load is connected can be kept in the target range as much as possible. Moreover, according to said setting, since the no-load rotation speed requested | required at a standby operation process does not become an excessively large speed, the enlargement of an installation can be suppressed as much as possible.

  According to a third characteristic configuration of the control method of the power generation system according to the present invention, in the first or second characteristic configuration of the control method, the power connected to the primary winding with respect to the total power consumed by the power load. When the load factor, which is the ratio of the connected load power of the load, is less than the set load factor, the rotational speed at no load is set to a rotational speed that increases as the load factor increases, and the load factor is When the load factor is equal to or higher than the load factor, the rotational speed at no load is set to the maximum rotational speed of the engine.

According to said characteristic structure, the engine rotational speed at the time of a no-load state (at the time of a standby driving process) can be set to the appropriate rotational speed according to the magnitude | size of the electric power load to connect.
That is, if the load factor, which is the ratio of the connected load power of the power load connected to the primary winding to the total power consumed by the power load, is less than the set load factor, it is due to mechanical constraints of the engine. Since the decrease in the frequency of the output power when the power load is connected can be kept within the target range at an engine rotation speed less than a certain maximum rotation speed, the no-load rotation speed is set to the rotation speed.
On the other hand, when the load factor is equal to or greater than the set load factor, the engine speed is required to be higher than the maximum speed in order to keep the decrease in the frequency of the output power when the power load is connected within the target range. Considering the restrictions, set the no-load rotation speed to the maximum rotation speed.
By setting the no-load rotation speed in this way, it is possible to suppress the reduction in the frequency of the output power when the power load is connected to the target range as much as possible while suppressing the enlargement of the power generation system as much as possible.

  According to a fourth characteristic configuration of the control method of the power generation system according to the present invention, in the first to third characteristic configurations of the control method, the engine in the no-load state before performing the standby operation step with respect to the independent operation. Driving the rotor by the first power converter and exciting the primary winding by the first power converter and a secondary side exciting process of exciting the secondary winding by the second power converter. Both are executed, and a primary side voltage establishing step is performed with a primary side voltage generated on the primary side of the secondary excitation induction generator as a target voltage value. In the primary side voltage establishing step, the primary side excitation step is performed. The reactive power is supplied from the first power converter to the primary winding.

According to the above configuration, the power necessary to operate the secondary excitation type induction generator at the time of self-sustained start-up of the power generation system is obtained from the first power converter as well as the second power converter. Supply as. Thereby, according to the magnitude | size of the reactive power supplied to a primary winding from a 1st power converter, the electric power supplied to a secondary winding from a 2nd power converter can be reduced, and a 2nd power converter Therefore, it is possible to prevent the power supplied to the secondary winding from becoming excessive.
Therefore, it is not necessary to employ an element or device configuration that can withstand excessive supply power, so that it is possible to suppress an increase in equipment cost of the power generation system and an increase in size of the device that constitutes the power generation system.

  According to a fifth characteristic configuration of the control method of the power generation system according to the present invention, in the fourth characteristic configuration of the control method, the primary side voltage establishing step converts the primary side voltage to the target voltage value by the secondary side excitation step. The delay type primary side voltage establishment step is to start the primary side excitation step after performing the step of boosting up to the first step, and in the delay type primary side voltage establishment step, the primary side voltage is increased after the step of boosting. While maintaining the target voltage value, the reactive power supplied from the first power converter to the primary winding is increased, and the power supplied from the second power converter to the secondary winding is increased. It is in the point to reduce.

  According to the above characteristic configuration, in the self-sustaining start-up of the power generation system, since the primary power excitation is started by the first power converter after the primary voltage reaches the target voltage value, the primary voltage establishing step (primary Side voltage establishment processing) can be shortened. Note that the power supplied to the secondary winding from the second power converter is excessive between the time when the primary voltage reaches the target voltage value and the time when the first power converter starts exciting the primary winding. There is a possibility. However, even if the power becomes excessive, when the excitation of the primary winding by the first power converter is started, the reactive power supplied from the first power converter to the primary winding is increased and the second power is increased. Since the power supplied to the secondary winding from the power converter is reduced, it is avoided that such a state lasts for a long time. Therefore, also in the said structure, it can suppress that the electric power supplied to a secondary winding from a 2nd power converter becomes excessive.

Schematic configuration diagram of a power generation system using a secondary excitation induction generator The control block diagram of the control apparatus of the electric power generation system which concerns on this invention The flowchart which shows control of the independent operation of the electric power generation system which concerns on this invention The graph which shows control of the gas engine rotational speed of the electric power generation system which concerns on this invention The graph which shows the fluctuation | variation of the frequency of the output electric power of the electric power generation system which concerns on this invention The graph which shows the relationship between a load factor and the no-load rotation speed of a suitable gas engine The graph which shows the fluctuation of the engine speed of the power generation system which uses the synchronous generator The graph which shows the fluctuation of the frequency of the output electric power of the electric power generation system which uses the synchronous generator

  An embodiment of a control device (control method) for a power generation system according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the structure described in embodiment and drawing demonstrated below, A various modification | change is possible if it is a structure with the same effect.

1. Overall Configuration of Power Generation System FIG. 1 shows a power generation system 1 to be controlled by the control device 100 (see FIG. 2) according to the present embodiment. The power generation system 1 includes a secondary excitation induction generator (double-feed winding induction generator) 2, a gas engine 3, a first power converter 11, a second power converter 12, and a power storage device 5. , A first switch 21, a second switch 22, and a third switch 23. The secondary excitation induction generator 2 generates power (three-phase AC power) having the same frequency (for example, 50 [Hz] or 60 [Hz]) as the power system (commercial power system) 4, and the power Can be supplied to the load 7 and the power system 4 that consume power. Examples of the load 7 include an indoor unit, an outdoor unit, an electric lamp, and the like included in the air conditioning equipment. In the present embodiment, the third switch 23 and the load 7 correspond to the “changeover switch” and the “power load” in the present invention, respectively.

  The power generation system 1 can start the system in a state in which power is supplied from the power system 4 and is in a state in which power is not supplied from the power system 4 (the second switch 22 is opened). In this state, the system can be activated (independently activated) by the electric power supplied from the power storage device 5.

  The secondary excitation induction generator 2 includes a stator 2b (stator) having a primary winding (not shown) and a rotor 2a (rotor) having a secondary winding (not shown). Yes. The primary winding included in the stator 2 b is connected to the power system 4 via the first switch 21 and the second switch 22. The primary winding provided in the stator 2 b is also connected to the load 7 via the first switch 21 and the third switch 23. On the other hand, the secondary winding included in the rotor 2 a is connected to the filter circuit 10, the second power converter 12, the DC unit 13, the first power converter 11, the filter circuit 10, the transformer 6, and the second switch 22. Connected to the power system 4. The secondary winding included in the rotor 2 a is connected to the filter circuit 10, the second power converter 12, the DC unit 13, the first power converter 11, the filter circuit 10, the transformer 6, and the third switch 23. The load 7 is also connected.

  In the following description, the primary winding side included in the stator 2b is referred to as “primary side of the secondary excitation induction generator”, and the secondary winding side included in the rotor 2a is referred to as “secondary side of the secondary excitation induction generator”. " Therefore, the frequency of power (voltage, current) generated on the primary side of the secondary excitation induction generator 2 is the frequency of power supplied to the load 7 and the power system 4.

  The gas engine 3 is mechanically connected to the rotor 2a of the secondary excitation induction generator 2, and rotationally drives the rotor 2a. In this example, the output shaft of the gas engine 3 is directly connected so as to rotate integrally with the rotor 2a, and the rotational speed of the gas engine 3 and the rotational speed of the rotor 2a are equal. Note that a gear mechanism may be provided between the output shaft of the gas engine 3 and the rotor 2a. The gas engine 3 is an engine that uses city gas as fuel. In this example, the gas engine 3 serves as a corner of a cogeneration facility that can supply heat in addition to electric power in parallel in addition to electric power. In the present invention, for example, a gas engine 3 having a rated output of 1 [kW], several tens [kW], several [MW], or the like can be used.

  The first power converter 11 is connected to the stator 2b (primary winding) of the secondary excitation induction generator 2 via the first switch 21 on the AC side (right side in FIG. 1), and the second switch 22 is connected to the electric power system 4 through the third switch 23, and is further connected to the load 7 through the third switch 23. The first power converter 11 is connected to the DC unit 13 on the DC side (left side in FIG. 1). The second power converter 12 is connected to the rotor 2a (secondary winding) of the secondary excitation induction generator 2 on the AC side (left side in FIG. 1). Further, the second power converter 12 has a DC side (right side in FIG. 1) connected to the DC unit 13. Each of the first power converter 11 and the second power converter 12 has a function as an inverter that converts (reversely converts) DC power on the DC side into AC power and supplies the AC power to the AC side. It is configured to be able to perform both of the function as a converter that converts (forward-converts) AC power into DC power and supplies it to the DC side.

  The first power converter 11 and the second power converter 12 are configured to include a plurality of (for example, six) switching elements. As the switching element, power transistors having various structures such as a metal oxide semiconductor field effect transistor (MOSFET) and an insulated gate bipolar transistor (IGBT) can be employed. Then, a PWM (pulse width modulation) signal is input to the first power converter 11 and the second power converter 12, and the switching element performs a switching operation (on / off operation) based on the PWM signal. The PWM signal for operating the first power converter 11 and the second power converter 12 is generated by the control device 100 (see FIG. 2).

  As shown in FIG. 1, a filter circuit 10 including an inductance and a capacitor is provided on both the AC side of the first power converter 11 and the AC side of the second power converter 12. The filter circuit 10 is a filter that removes high-frequency components generated by switching of the switching element, and the output voltage waveform from the first power converter 11 and the second power converter 12 is sinusoidal by the filter circuit 10. Converted.

  Moreover, as shown in FIG. 1, the transformer 6 is provided in the secondary excitation induction generator 2 side (electric power system 4 side) rather than the filter circuit 10 provided in the alternating current side of the 1st power converter 11. FIG. Yes. In the following description, “the primary side of the transformer” refers to the first power converter 11 side of the transformer 6 (the side labeled with “# 1” in FIG. 2), and “the secondary side of the transformer”. Indicates the secondary excitation induction generator 2 side of the transformer 6 (the power system 4 side, the side labeled “# 2” in FIG. 2).

  The DC unit 13 is a part that connects the DC side of the first power converter 11 and the DC side of the second power converter 12. The DC unit 13 includes a capacitor 8 and a power storage device 5. The power storage device 5 supplies electric power required when the power generation system 1 is activated independently. It is also possible to suppress fluctuations in the power supplied to the load 7 and the power system 4 using the power storage device 5. The power storage device 5 is configured by, for example, a storage battery, an electric double layer capacitor, or the like, and can supply and discharge power to the direct current unit 13 and can be charged by receiving power from the direct current unit 13. Composed. A switch may be interposed between the power storage device 5 and the DC unit 13.

  The first switch 21 selectively connects the stator 2 b (primary winding) of the secondary excitation induction generator 2 and the first power converter 11. The second switch 22 selectively connects the power system 4 and the first power converter 11. The first switch 21 cooperates with the second switch 22 to selectively connect the stator 2b (primary winding) of the secondary excitation induction generator 2 and the power system 4, and to the third switch 23. In cooperation, the stator 2b (primary winding) of the secondary excitation induction generator 2 and the load 7 are selectively connected. The second switch 22 selectively connects the power system 4 and the load 7 in cooperation with the third switch 23.

  Each of the first switch 21, the second switch 22, and the third switch 23 is controlled to open / close based on an open / close signal generated by a switch control unit 104 (not shown) of the control device 100. These switches can be, for example, electromagnetic contact type switches that open and close by the operation of an electromagnet.

The power generation system 1 having the above configuration is a system with a high degree of freedom with respect to the frequency (voltage, current frequency) of the generated power. Although a detailed description is omitted (for details, see, for example, Patent Document 1), the frequency of the output power of the generated power of the power generation system 1 (the primary side voltage v1 induced on the primary side of the secondary excitation induction generator 2). The frequency (see FIG. 4)) is f1, the rotational frequency of the rotor 2a is f0, and the alternating current (alternating voltage) supplied to the secondary winding to excite the secondary winding of the rotor 2a If the frequency of f2 is f2, then “f1 = f0 + f2”.
Here, the rotation frequency f0 of the rotor 2a is obtained from “f0 = m × n / 120” where the rotation speed of the rotor 2a is m [rpm] and the number of magnetic poles of the secondary excitation induction generator 2 is n. .

  For example, when the rotation speed of the rotor 2a is 1100 [rpm] and the number of magnetic poles of the secondary excitation induction generator 2 is “6”, the rotation frequency f0 of the rotor 2a is 55 [Hz]. Therefore, in this case, if the second power converter 12 is controlled to supply an AC current (AC voltage) having a frequency of 5 [Hz] to the secondary winding (f2 = 5 [Hz]), the frequency is the target. AC power with a frequency of 60 [Hz] can be obtained. Conversely, if the second power converter 12 is controlled to extract an AC current (AC voltage) having a frequency of 5 [Hz] from the secondary winding (f2 = −5 [Hz]), the frequency will be the target frequency. AC power of 50 [Hz] can be obtained. Note that any rotation speed other than the synchronous rotation speed can be selected as the rotation speed of the rotor 2a (that is, the rotation speed of the gas engine 3). The synchronous rotation speed is 1200 [rpm] when the frequency of the power system 4 is 60 [Hz], which is the target frequency, and the number of magnetic poles of the secondary excitation induction generator 2 is “6”. .

  Thus, even if the rotation speed of the rotor 2a (that is, the rotation speed of the gas engine 3) is the same, the frequency f2 of the alternating current supplied to the secondary winding of the rotor 2a (as described above, The frequency f1 of the output power can be changed by changing a negative value when AC current is extracted from the secondary winding. Therefore, for example, there is an advantage that the gas engine 3 having the same specification can be used in an area with a target frequency of 50 [Hz] and an area with 60 [Hz]. Further, by appropriately selecting the rotational speed of the gas engine 3 according to the electric power load, the partial load efficiency of the gas engine 3 can be improved, or the rotational speed of the gas engine 3 can be increased, so that the entire power generation system 1 is improved. The output (rated output) can be increased.

2. Configuration of Control Device Next, the configuration of the control device 100 will be described in detail based on FIG. Here, as shown in FIG. 2, active power and reactive power generated on the primary side of the secondary excitation induction generator 2 are referred to as first active power P1 and first reactive power Q1, respectively. The active power and reactive power supplied to the secondary side of the secondary excitation induction generator 2 are referred to as second active power P2 and second reactive power Q2, respectively. Further, active power and reactive power supplied from the primary side of the secondary excitation induction generator 2 to the first power converter 11 side are referred to as third active power P3 and third reactive power Q3, respectively. And the arrow which shows the flow of these electric power in FIG. 2 has shown the flow direction in case the value of the said electric power is positive. In this example, regarding the positive and negative of the reactive power, the case where the delayed reactive power (reactive power in the delayed phase) is positive is positive, and the case where the delayed reactive power is negative is negative. Here, “the delayed reactive power is positive” means that the phase of the current is advanced with respect to the voltage, and “the delayed reactive power is negative” means that the phase of the current is delayed with respect to the voltage. Means the case. If the resistance component can be ignored, the phase difference between the current and voltage is 90 degrees.

  As shown in FIG. 2, the control device 100 includes a first control unit 101 that controls the operation of the first power converter 11, a second control unit 102 that controls the operation of the second power converter 12, A switch control unit 104 that controls the open / closed state of the switch 21, the second switch 22, and the third switch 23. These functional units have a hardware or software (program) or a functional unit for performing various processes on the input data, with an arithmetic processing unit such as a CPU common to each other or independent from each other as a core member. Implemented and configured by both. These functional units are configured to exchange information with each other via a communication line such as a digital transfer bus. Here, when these functional units are configured by software (program), the software is stored in a storage unit such as a RAM or a ROM that can be referred to by the arithmetic processing unit. In this embodiment, the 1st control part 101 and the 2nd control part 102 comprise the "primary side voltage establishment part which performs a primary side voltage establishment process" in this invention.

  The control device 100 operates the first control unit 101 and the second control unit 102, and does not receive the supply of power from the power system 4 (the second switch 22 (see FIG. 1) is opened). ), The system can be activated (independent activation) by the electric power supplied from the power storage device 5. Hereinafter, the configurations of the second control unit 102 and the first control unit 101 will be described in order.

2-1. Configuration of Second Control Unit The second control unit 102 is a functional unit that controls the operation of the second power converter 12 (specifically, the switching operation of the switching element included in the second power converter 12). The second control unit 102 is configured to control the operation of the second power converter 12 and to supply the AC power generated by the second power converter 12 to the secondary winding provided in the rotor 2a. Yes. That is, the second control unit 102 serves as secondary-side excitation means for performing a step of exciting the secondary winding of the rotor 2a by the second power converter 12 (hereinafter referred to as “secondary-side excitation step”). Function.

  In the present embodiment, the second control unit 102 performs voltage feedback control based on the primary side voltage v1 as the secondary side excitation process. Therefore, the power generation system 1 includes a voltage sensor (not shown) that detects the primary side voltage v1. And the 2nd control part 102 performs this voltage feedback control at the time of the independent starting of the electric power generation system 1, so that it may mention later.

  Specifically, the second control unit 102 includes a functional unit as shown in FIG. 2, and performs voltage feedback control using the primary side voltage v1 as a feedback value and the primary side voltage command value V1 * as a command value. Execute. Note that the flow of the voltage feedback control process executed by the second control unit 102 is clear from the block diagram shown in FIG. 2, and therefore the flow will be briefly described here. In the following description of the control processing, characters described in each function unit in FIG. 2 are enclosed in square brackets (“”) and represent a function unit corresponding to the character. In the present embodiment, the primary side voltage command value V1 * corresponds to the “target voltage value” in the present invention.

  The primary voltage v1 detected by the voltage sensor is input to “PLL”. “PLL” detects the angular velocity (angular frequency) ω0 of the primary voltage v1 by performing PLL (Phase Locked Loop) processing, and outputs the information to “1 / s”. “1 / s” performs an integration process for integrating the angular velocity sent from “PLL”, and derives a first reference phase θ1 as a reference for three-phase to two-phase conversion.

  The primary side voltage v1 detected by the voltage sensor is also input to “dq ← abc”. In “dq ← abc”, based on the first reference phase θ1, the primary side voltage v1 is changed from a three-phase (a-phase, b-phase, c-phase) AC coordinate system (abc coordinate system) to a two-phase rotational coordinate system ( dq coordinate system) to derive the d-axis component v1d and the q-axis component v1q of the primary voltage v1. In this example, the first reference phase θ1 is set so that the q-axis component v1q of the primary side voltage v1 is zero.

  Then, the d-axis component v1d and the q-axis component v1q of the primary side voltage v1 obtained by “dq ← abc” are sent to “v1dq = √ (v1d2 + v1q2)”, and the amplitude value v1dq of the primary side voltage v1 is calculated. The Then, the amplitude value v1dq is compared with V1 * which is the command value (target value) of the output voltage of the secondary excitation induction generator 2, and proportional integral control is performed by “PI” so that the difference becomes zero. Calculation (PI control calculation) is performed. The primary voltage command value V1 * is multiplied by a coefficient as necessary (according to the winding connection method or the like), and then compared with the amplitude value v1dq. For example, when the primary side voltage command value V1 * is expressed by the effective value of the line voltage, the coefficient can be set to “√ (2/3)”.

  “PI” performs a PI control calculation and derives a d-axis component urd and a q-axis component urq of the voltage command value. Then, the d-axis component urd and the q-axis component urq of the voltage command value are sent to “dq → abc”, and two-phase three-phase conversion from the dq coordinate system to the abc coordinate system is executed. As described above, in this example, since the first reference phase θ1 is set so that the q-axis component v1q of the primary side voltage v1 becomes zero, the q-axis component urq of the voltage command value becomes zero. . Therefore, in this example, “PI” obtains only the d-axis component urd of the voltage command value, the d-axis component urd is input to “dq → abc”, and the voltage command value of “dq → abc” “0” is input as the q-axis component urq.

  Further, “1 / s” derives the second reference phase θ2 based on the difference (ω0−ωr) between the angular velocity ω0 of the primary side voltage v1 and the angular velocity ωr of the rotor 2a (the above rotation frequency f0 × 2π). The angular velocity ωr of the rotor 2a can be detected by a magnetic pole position sensor (such as a resolver) (not shown). “Dq → abc” performs two-phase three-phase conversion on the d-axis component urd and the q-axis component urq of the voltage command value based on the second reference phase θ2, and sets the execution result to “PWM”. Output. “PWM” is a PWM signal (gate drive signal) for switching control of the switching element included in the second power converter 12 based on the three-phase voltage command value sent from “dq → abc”. Generate.

  The above is the flow of voltage feedback control executed by the second control unit 102. Although not described in detail, the first active power P1 and the first reactive power Q1 generated by the second control unit 102 on the primary side of the secondary excitation induction generator 2 during normal operation of the power generation system 1 are described. It can be configured to perform feedback control (power feedback control) using as a feedback value. In such a configuration, in a steady state where the resistance component can be ignored, the first active power P1 is converted into the d-axis component (secondary component) of the secondary current i2 that is the current flowing through the secondary side of the secondary excitation induction generator 2. Side d-axis current), and the first reactive power Q1 can be controlled by the q-axis component (secondary q-axis current) of the secondary current i2. That is, the first active power P1 and the first reactive power Q1 can be controlled independently of each other.

2-2. Configuration of First Control Unit The first control unit 101 is a functional unit that controls the operation of the first power converter 11 (specifically, the switching operation of the switching element included in the first power converter 11). The first control unit 101 is configured to control the operation of the first power converter 11 and to supply the AC power generated by the first power converter 11 to the primary winding included in the stator 2b. Yes. That is, the first control unit 101 functions as a primary side excitation unit that executes a step of exciting the primary winding of the stator 2b by the first power converter 11 (hereinafter referred to as “primary side excitation step”).

  In this embodiment, the 1st control part 101 performs the current feedback control based on the electric current (this example transformer secondary side current ig) which flows into the alternating current side of the 1st power converter 11 as a primary side excitation process. . Therefore, the power generation system 1 includes a current sensor 30 that detects the transformer secondary current ig. And the 1st control part 101 performs this electric current feedback control at the time of the independent starting of the electric power generation system 1, so that it may mention later.

  Specifically, the first control unit 101 includes a functional unit as shown in FIG. 2, and current feedback control is performed using the transformer secondary current ig as a feedback value and the current command value Ig * as a command value. Execute. Note that the flow of the current feedback control process executed by the first control unit 101 is clear from the block diagram shown in FIG. 2, and therefore the flow will be briefly described here. In the following description of the control process, as in the description of the second control unit 102, the characters described in each function unit in FIG. 2 are enclosed in square brackets, and the function unit corresponding to the character is To express.

  The transformer secondary current ig detected by the current sensor 30 is input to “dq ← abc”. The above-mentioned first reference phase θ1 is also input to “dq ← abc”. Then, “dq ← abc” performs three-phase two-phase conversion on the transformer secondary current ig based on the first reference phase θ1, and the d-axis component igd of the transformer secondary current ig and A q-axis component igq is derived.

  Then, the d-axis component “igd” of the transformer secondary current “igd” is compared with the d-axis component “Igd *” of the current command value Ig *, and the PI control calculation is executed at “PI” so that the difference becomes zero. Then, non-interference control for improving controllability is executed on the result. Specifically, the sum of the output of “PI” multiplied by (−1) and ω0 × Lg × igq is derived. Then, the d-axis component v1d of the primary side voltage v1 is added to the derivation result to derive the d-axis component ugd of the voltage command value. Here, Lg is an inductance obtained by converting the positive phase reactance of the transformer 6 to the secondary side.

  Similarly, the q-axis component igq of the transformer secondary current ig and the q-axis component Igq * of the current command value Ig * are compared, and the PI control calculation is performed at “PI” so that the difference becomes zero. The non-interference control for improving the controllability is executed on the result. Specifically, a value obtained by subtracting ω0 × Lg × igd from the output of “PI” multiplied by (−1) is derived. Then, the q-axis component v1q (“0” in this example) of the primary side voltage v1 is added to the derivation result, and the q-axis component ugq of the voltage command value is derived.

  “Abc ← dq” performs two-phase three-phase conversion on the d-axis component ugd and the q-axis component ugq of the voltage command value based on the first reference phase θ1, and outputs the execution result to “PWM”. “PWM” is a PWM signal (gate drive signal) for switching control of the switching element included in the first power converter 11 based on the three-phase voltage command value sent from “abc ← dq”. Generate.

  The above is the flow of current feedback control executed by the first control unit 101. As will be described later, the first control unit 101 controls the third reactive power Q3 when the power generation system 1 is independently activated. In this example, as described above, the q-axis component v1q of the primary side voltage v1 is zero. Therefore, the third reactive power Q3 can be controlled by the q-axis component igq of the transformer secondary current ig. In this case, the current command value Ig * has at least its q-axis component Igq *. On the other hand, since the third active power P3 can be controlled by the d-axis component igd of the transformer secondary current ig, when the third active power P3 is positively controlled, the current command value Ig * is And d-axis component Igd *.

  Although not described in detail, during the normal operation of the power generation system 1, the first control unit 101 performs feedback control so that the voltage Vdc is constant with the voltage Vdc of the DC unit 13 as a feedback value. It can be constituted as follows.

3. Control of self-sustained operation Self-sustained operation means that the gas engine 3 is driven at a target rotational speed (for example, rated rotational speed), and power is supplied from the power storage device 5 without being supplied with power from the power system 4. 7 is an operation for supplying output power at a target frequency (50 [Hz] or 60 [Hz]). About this independent operation, it is comprised so that the control apparatus 100 as an independent operation control part may perform.
Below, with reference to FIG. 3, the control (control of a self-sustained operation) from the self-sustained start-up of the power generation system 1 executed in the control device 100 according to the present embodiment to the connection to the power load will be described. The self-sustained operation control described below is executed by hardware or software (program) or both constituting each functional unit of the control device 100. When each of these functional units is configured by a program, the arithmetic processing unit included in the control device 100 operates as a computer that executes the program that configures each functional unit.

  In FIG. 3, in the no-load state where the rotor 2a is driven by the gas engine 3 and the third switch 23 is opened, the first switch 21 is closed and the second switch 22 is The flow of processing from when the power generation system 1 (secondary excitation induction generator 2) is activated independently to supply power to the load 7 from the open state is shown. In addition, although the 2nd switch 22 is made into the closed state instead of an open state, also when it exists in the state which cannot supply electric power from the electric power grid | system 4, the process demonstrated here can be performed similarly. After the gas engine 3 is started by a cell motor, for example, the gas engine 3 is not connected to an electric power load (excluding energy necessary for rotating the rotor 2a), and the predetermined rotation speed (for example, the efficiency of the gas engine 3 is high). Rotation speed, rated rotation speed, etc.) are assumed to be stable at the predetermined rotation speed in a no-load state where the power load is not connected. Further, when the power generation system 1 is autonomously started, the power storage device 5 is in a state in which power can be supplied to the DC unit 13, and the secondary winding included in the rotor 2 a or It supplies to the primary winding with which stator 2b is provided.

3-1. Independent start-up (step-up process, primary side excitation process)
As shown in FIG. 3, the control device 100 operates only the second power converter 12 of the first power converter 11 and the second power converter 12 by the second control unit 102 and executes the boosting step. (Step # 1). Here, the “boosting step” is a step of performing a boosting process for boosting the primary side voltage v1 to the primary side voltage command value V1 * by the secondary side excitation step. That is, after the “boost process” is performed, the primary side voltage v1 and the primary side voltage command value V1 * become equal. In this boosting step, the second control unit 102 executes the voltage feedback control described above.

  Here, the primary-side voltage command value V1 * is a voltage that determines the output voltage (primary-side voltage v1) of the secondary excitation induction generator 2 as described above. It can be set to 200 [V], 3300 [V], 6600 [V], or the like. The primary voltage command value V1 * is preferably configured to increase in a slope shape toward the set value (soft start), and the amplitude of the primary voltage v1 is preferably increased in a slope shape from the viewpoint of stability. . For example, the primary voltage command value V1 * can be raised to the set value at a rate of 400 [V / sec] in terms of the effective value of the line voltage.

  Note that the maximum value (peak value) of the amplitude when the primary side voltage v1 is expressed by a phase voltage (for example, a phase voltage of the a phase) is v1am (unit [V]), and the primary side voltage command value V1 * is between the lines. Assuming that the voltage is an effective value (unit [V]), in this embodiment, the state of v1am = V1 * × √ (2/3) is the primary voltage v1 and the primary voltage command value V1 *. Are equal. Thus, “the state where the primary side voltage v1 is boosted to the primary side voltage command value V1 *” and “the state where the primary side voltage v1 and the primary side voltage command value V1 * are equal”, and the same meaning as these, This means a state in which the value of v1 and the value of V1 * are equal to each other after being multiplied by a coefficient if necessary (according to a method for connecting windings or the like).

  After execution of the boosting step by the second control unit 102, that is, after the primary side voltage v1 is boosted to the primary side voltage command value V1 *, the first control unit 101 of the control device 100 turns the first power converter 11 on. Operate and execute the primary side excitation process (step # 2). In addition, the 1st control part 101 performs the electric current feedback control mentioned above as a primary side excitation process. Specifically, the first control unit 101 controls the first power converter 11 so that the first power converter 11 generates reactive power (in this example, positive delayed reactive power). In this case, since the third reactive power Q3 is a negative value and the third switch 23 is in the open state, the first reactive power Q1 is also a negative value (a value substantially equal to the third reactive power Q3). Thereby, positive delayed reactive power is supplied from the first power converter 11 to the primary winding included in the stator 2b of the secondary excitation induction generator 2. That is, the 1st control part 101 performs control which supplies reactive power (in this example, positive delay reactive power) from the 1st power converter 11 to a primary winding as a primary side excitation process.

  When performing the primary side excitation process, the first control unit 101 sets a current command value Ig * corresponding to the desired delayed reactive power (third reactive power Q3). As described above, in this example, the third reactive power Q3 can be controlled by the q-axis component igq of the transformer secondary current ig. Therefore, the first control unit 101 sets at least the q-axis component Igq * having a value other than zero as the current command value Ig *. When the first power converter 11 actively generates active power as well as positive delayed reactive power, the current command value Ig * is set so that the d-axis component Igd * also has a value other than zero. To do.

  It is preferable from the viewpoint of stability that the current command value Ig * is configured to increase in a slope shape toward the set value (soft start), and the amplitude of the transformer secondary side current ig is increased in a slope shape. It is. For example, the current command value Ig * is obtained by multiplying the maximum value (unit [V]) of the line current iga of a phase (for example, a phase) of the transformer secondary current ig by √ (3/2). If it is, the current command value Ig * can be raised to the set value at a rate of 6 [V / sec].

  Note that the second control unit 102 executes the secondary side excitation process even after the primary side voltage v1 is boosted to the primary side voltage command value V1 *, and maintains the primary side voltage v1 at the primary side voltage command value V1 *. Then, the second power converter 12 is controlled. That is, in step # 2, the first control unit 101 executes current feedback control, and the second control unit 102 executes voltage feedback control. And in this state, since a part of electric power which the secondary excitation induction generator 2 requires is supplied as reactive power from the 1st power converter 11, primary side voltage v1 is made into primary side voltage command value V1 *. The power (at least the second reactive power Q2) that needs to be supplied to the secondary winding in order to maintain it is less than when the boosting step (step # 1) is completed. Therefore, the power generated by the second power converter 12 (from the second power converter 12 to the secondary winding) in accordance with the increase of the positive delay reactive power supplied from the first power converter 11 to the primary winding. The second control unit 102 controls the second power converter 12 so that (supplied power) decreases. By setting it as such a structure, it is possible to suppress that the electric power supplied to the secondary winding from the 2nd power converter 12 becomes excessive.

  In this example, when the positive delay reactive power supplied from the first power converter 11 to the primary winding is increased, the power supplied from the second power converter 12 to the secondary winding is decreased. The current flowing through the secondary winding (secondary current i2) is reduced. In addition, it can also be set as the structure which also reduces the secondary side voltage v2 which is the voltage induced by the secondary side of the secondary excitation induction generator 2 with the reduction | decrease of the secondary side electric current i2.

  After execution of the primary side excitation step (step # 2), the primary side voltage v1 is set to the primary side voltage command value V1 * and the reactive power supplied to the primary winding of the secondary excitation induction generator 2 Or the electric power supplied to the secondary winding of the secondary excitation induction generator 2 has a desired value. This state is a primary voltage established state in which connection with the load 7 is possible.

  As described above, the control device 100 (the first control unit 101 and the second control unit 102) performs both the primary side excitation process and the secondary side excitation process in a no-load state, in other words, Both the primary power converter 11 and the secondary power converter 12 are operated to establish the primary side voltage with the primary side voltage v1 generated on the primary side of the secondary excitation induction generator 2 as the primary side voltage command value V1 *. A process (primary side voltage establishment process) is executed. In this example, as described above, after the boosting step, the positive voltage supplied from the first power converter 11 to the primary winding in the state where the primary voltage v1 is maintained at the primary voltage command value V1 *. The delay reactive power is increased, and the power supplied from the second power converter 12 to the secondary winding is decreased. That is, in this example, the primary side voltage establishment process is a delayed primary side voltage establishment process (delayed primary side voltage establishment process) in which the primary side excitation process is started after the boosting process is executed.

3-2. Standby operation and connection to power load (standby operation process, load connection process)
When the primary voltage v1 is established by executing the delay-type primary voltage establishing step (step # 1 and step # 2) and the control device 100 is in a self-sustaining operation state, the third switch 23 is opened and connected to the load 7 In an unloaded state, the gas engine 3 is driven at a no-load rotation speed faster than the target rotation speed, and the output power of the primary winding of the secondary excitation induction generator 2 is controlled to the output power of the target frequency. A standby operation step is executed (step # 3). The control device 100 includes a rotation speed control unit 103 that controls the rotation speed of the gas engine 3. The control device includes the rotation speed control unit 103, the first control unit 101, and the second control unit 102. By 100, it is comprised so that a standby operation process may be performed.

Then, after the standby operation process (step # 3) is performed, a load connection process is performed in which the third switch 23 is closed and the primary winding is connected to the load 7 (step # 4). As described above, the control device 100 includes the switch control unit 104 that controls the open / close state of the third switch 23, and includes the switch control unit 104, the first control unit 101, and the second control unit 102. The control device 100 is configured to execute the load connection process. Thereby, the electric power generated by the secondary excitation induction generator 2 is supplied to the load 7 that requires electric power. By enabling such self-sustained operation, it is possible to supply power to the important load (load 7) from the power generation system 1 even when it is disconnected from the power system 4, and serve as an emergency power source in the event of a power failure It becomes possible to bear.

  Hereinafter, the control in the standby operation process (step # 3) and the effect of the control will be described with reference to FIGS.

  FIG. 4 is a graph showing the control of the rotational speed of the gas engine 3 in the power generation system 1. In FIG. 4, the state of control of the rotational speed of the gas engine 3 in the power generation system 1 is indicated by a solid line, and the state of control when a conventional synchronous generator is used as a generator is indicated by a broken line. The target rotational speed of the gas engine 3 in FIG. 4 is 1200 [rpm]. However, in the power generation system 1 according to the present embodiment, in the range of FIG. The gas engine 3 is operated at 1500 [rpm] (no-load rotation speed) higher than the target rotation speed 1200 [rpm].

  4B, the third switch 23 is closed, and the power generation system 1 is connected to the load 7 that is 30% of the rated load. As can be seen in FIG. 4C, the rotational speed of the gas engine 3 also decreases in this embodiment due to the connection to the load 7 (solid line). ).

  FIG. 5 shows a change in the frequency f1 of the output power of the power generation system 1 when the rotation speed of the gas engine 3 is controlled as shown in FIG. FIGS. 5A, 5B, and 5C correspond to the timings of FIGS. 4A, 4B, and 4C, respectively.

  In FIG. 5, in the range of (A) before connection to the load 7, as shown in FIG. 4 (A), the no-load rotational speed 1500 [rpm], which is higher than the target rotational speed 1200 [rpm]. ]. In the range of FIG. 5A, the control device 100 controls the secondary excitation induction generator 2 to stabilize the frequency f1 of the output power of the power generation system 1 at the target frequency of 60 [Hz]. In other words, the control device 100 controls the frequency f2 of the alternating current supplied to the secondary winding in order to excite the secondary winding of the rotor 2a based on the rotational frequency f0 of the rotor 2a. The frequency f1 of power is stabilized at the target frequency of 60 [Hz].

  When connected to the load 7 in FIG. 5 (B), the frequency f1 of the output power of the power generation system 1 once decreases in the present embodiment (solid line) as in the prior art (broken line) (FIG. 5C )). However, the decrease in the frequency f1 of the output power in the present embodiment (solid line) is smaller than that in the conventional technique (broken line). That is, as seen in FIG. 4 (C), immediately after connection to the load 7, since the change in the rotational speed of the gas engine 3 is large, the frequency f1 of the output power slightly decreases in this embodiment as well. In this embodiment, since the subsequent change in the rotational speed of the gas engine 3 is more gradual than in the prior art, fluctuations in the frequency f1 of the output power when the power load is connected can be suppressed, as shown in FIG. As described above, it can be controlled at a target frequency of 60 [Hz].

  As described above, according to the control method and the control device of the power generation system according to the present invention, it is possible to suppress the decrease in the frequency of the output power when the power load is connected as compared with the case where the conventional control method and the control device are used. Therefore, it becomes possible to connect to a larger power load.

  In FIG. 4C, after connecting to the load 7, the rotational speed of the gas engine 3 is set to a rotational speed 1250 [rpm] near the target rotational speed, which is different from the target rotational speed 1200 [rpm]. Although this is controlled, this is merely an example showing an example in which the power of the target frequency is supplied to the load 7 while always controlling the frequency supplied to the secondary winding by the second power converter 12. Therefore, it is not always necessary to control the engine rotation speed as described above, and it may be configured such that the engine rotation speed is set to the target rotation speed 1200 [rpm] without performing the above-described frequency control after connection to the load 7.

3-3. Setting of the preferred no-load rotation speed in the standby operation process The preferred setting of the no-load rotation speed in the standby operation process will be described with reference to FIG. FIG. 6 is a graph showing a preferred no-load rotation speed of the gas engine 3 when the reduction in the frequency f1 of the output power of the power generation system 1 when the power load is connected is targeted to be within 5%. is there. In the power generation system 1 according to FIG. 6, the maximum rotation speed of the gas engine 3 is 1500 [rpm].

  When the load factor is 0% in the range of FIG. 6 (i) where the load factor, which is the ratio of the connected load power of the load 7 connected to the primary winding to the total power consumed by the power load, is 30% or less The power load starts at a rotational speed of 1500 [rpm] or less, which is the maximum rotational speed of the gas engine 3, starting from a rotational speed of 1250 [rpm] to a rotational speed of 1500 [rpm] when the load factor is 30%. The decrease in the frequency f1 of the output power of the power generation system 1 at the time of connection can be kept within the target range of 5%. Accordingly, in the range of FIG. 6 (i), the no-load rotation speed increases with an increase in the load factor (the size of the connected load 7), and the frequency f1 of the output power when connected to the load. It is preferable to set the rotation speed so that the decrease can be kept within the target range of 5%.

  On the other hand, in the range of FIG. 6 (iii) where the load factor is 30% to 60% of the rated load, in order to suppress the decrease in the frequency f1 of the output power of the power generation system 1 when the power load is connected to within 5%, It is necessary to drive the gas engine 3 at a rotational speed exceeding the maximum rotational speed 1500 [rpm]. However, due to mechanical constraints, the gas engine 3 cannot be driven at a rotational speed exceeding the maximum rotational speed 1500 [rpm]. Therefore, in the range of FIG. 6 (iii), in order to suppress the decrease in the frequency f1 of the output power of the power generation system 1 when the power load is connected as much as possible, the no-load rotation speed is the maximum rotation speed of the gas engine 3. It is preferable to set it to 1500 [rpm].

  As described above, in order to suppress the decrease in the frequency f1 of the output power of the power generation system 1 when the power load is connected to the target range as much as possible while suppressing the increase in size of the power generation system 1, the rotational speed at no load is Depending on the size (load factor) of the load 7 to be connected, the reduction in the frequency f1 of the output power when connected to the load 7 is not less than the rotation speed at which the reduction in the frequency f1 can be kept within the target range and not more than the maximum rotation speed It is preferable to set either the rotation speed or the maximum rotation speed of the gas engine 3.

  In addition, as described above, by setting the no-load rotation speed according to the load factor, the frequency range of the output power when the power load is connected can be reduced as much as possible while suppressing the enlargement of the power generation system as much as possible. A suitable no-load rotation speed can be set.

  It should be noted that it is preferable to set the no-load rotation speed faster in accordance with the increase in the load factor, and the load factor range in FIG. 6 (i) is suitable, and the no-load rotation speed is a constant value regardless of the increase in the load factor. The load factor in FIG. 6 (ii), which is a boundary with the range of the load factor in FIG. 6 (iii) that is preferably set to (maximum rotation speed), is a reference value for switching the setting method of the no-load rotation speed. By setting as a certain set load factor, the control device 100 can set a suitable no-load rotation speed.

6 (iv) is a load factor indicating the limit of the power load that can be connected to the power generation system 1. FIG. For the connected power load, it is not preferable that the frequency f1 of the supplied power fluctuates greatly. Therefore, the upper limit of the load 7 that can be connected to the power generation system 1 is set as an allowable limit depending on the degree of decrease in the frequency f1 of the output power of the power generation system 1 when the load 7 is connected.
In FIG. 6, the frequency f1 of the output power of the power generation system 1 when the power load is connected is increased as the load factor increases within the range of FIG. Decreases beyond the range (5%).
In FIG. 6 (iv) in which the load factor is 60%, the decrease in the frequency f1 of the output power of the power generation system 1 when the power load is connected reaches the allowable limit of 15%. For this reason, in the electric power generation system 1, the connection of the electric power load in which a load factor exceeds 60% is not recognized. Therefore, in the range exceeding FIG. 6 (iv), the rotation speed is not described (FIG. 6 (v)), and FIG. 6 (iv) as a boundary indicates the limit of the power load that can be connected to the power generation system 1. Load factor.

4). Other Embodiments Finally, other embodiments according to the present invention will be described. Note that the features disclosed in each of the following embodiments can be used only in that embodiment, and can be applied to other embodiments as long as no contradiction arises.

(1) In the above embodiment, as a preferable setting of the no-load rotation speed during the self-sustaining operation, in FIG. The case where the target is set as an example has been described. However, the embodiment of the present invention is not limited to this, and the target range of reduction in the frequency f1 of the output power is set to 3% or 10%, for example, depending on the nature of the connected load 7. You can also. In FIG. 6, as an example of the limit of the connectable power load, the limit of the power load that can be connected is described as an example of the limit of the power load that can be connected. However, the embodiment of the present invention is not limited to this, and the limit of the power load that can be connected according to the nature of the connected load 7, for example, the power at which the frequency of the output power is reduced by 10% or 20%. It can also be a load.

(2) In the above-described embodiment, the configuration in which the primary side voltage establishing step is the delayed primary side voltage establishing step has been described as an example. However, the embodiment of the present invention is not limited to this, and a configuration in which the primary-side excitation process is started before the boosting process by the secondary-side excitation process is completed is also preferable implementation of the present invention. One of the forms. That is, the primary side voltage v1 is boosted to the primary side voltage command value V1 * and the primary side voltage v1 is established while simultaneously executing the primary side excitation step and the secondary side excitation step in parallel. Can do. In this case, the primary side excitation process and the secondary side excitation process can be started simultaneously or substantially simultaneously. As described above, in the configuration in which the primary side excitation step and the secondary side excitation step are executed in parallel to boost the primary side voltage v1 to the primary side voltage command value V1 *, the secondary side current i2 is compared to the above embodiment. It is possible to keep the maximum value of the lower value lower and to keep the time during which the secondary current i2 is in an excessive state shorter.

(3) In the above embodiment, the configuration in which the current feedback control is executed based on the transformer secondary current ig in the primary side excitation process has been described as an example. However, the embodiment of the present invention is not limited to this. In the primary side excitation process, current feedback is based on the current on the primary side of the transformer 6 and the current on the stator 2b side with respect to the current sensor 30 in FIG. It can also be set as the structure which performs control.

(4) In the above embodiment, a configuration in which both the current feedback control by the first control unit 101 and the voltage feedback control by the second control unit 102 are based on proportional-integral control calculation (PI control calculation) is taken as an example. As explained. However, the embodiment of the present invention is not limited to this, and may be configured to execute a proportional integral differential control calculation (PID control calculation) instead of the proportional integral control calculation.

(5) In the above embodiment, in the primary side excitation process, current feedback control is performed based on the current (transformer secondary side current ig) flowing in the AC side of the first power converter 11, and in the secondary side excitation process, The configuration for performing voltage feedback control based on the primary side voltage v1 has been described as an example. However, the embodiment of the present invention is not limited to this, and at least one of the primary side excitation step and the secondary side excitation step is wound by a control method other than feedback control (for example, feedforward control). It is also possible to set it as the process of exciting a line.

(6) In the above embodiment, when the power supplied from the second power converter 12 to the secondary winding is reduced in the primary voltage establishing step, the current flowing through the secondary winding (secondary current i2 ) Is described as an example. However, the embodiment of the present invention is not limited to this, and may be configured to reduce only the secondary side voltage v2 without reducing the current flowing through the secondary winding (secondary side current i2). Is possible.

(7) In the above embodiment, a configuration in which the reference phase used by the first control unit 101 for controlling the first power converter 11 is the first reference phase θ1 derived by the second control unit 102 will be described as an example. did. However, the embodiment of the present invention is not limited to this, and the first control unit 101 includes a PLL function unit, and the reference phase used for control of the first power converter 11 is, for example, two of the transformer 6. It can be set as the structure calculated | required by PLL process based on the voltage of the next side. In this case, the 1st control part 101 becomes a structure which controls by the dq coordinate system on the basis of the transformer secondary side voltage.

(8) In the above embodiment, in the primary side excitation step, positive delay reactive power is generated in the first power converter 11 and positive delay reactive power is supplied from the first power converter 11 to the primary winding. The configuration has been described as an example. However, the embodiment of the present invention is not limited to this, and depending on the configuration of the secondary excitation induction generator 2 and the entire power generation system 1, a negative delay may occur in the first power converter 11 in the primary side excitation process. A configuration in which reactive power is generated and negative delayed reactive power is supplied from the first power converter 11 to the primary winding is also possible.

(9) Regarding other configurations as well, the embodiments disclosed herein are illustrative in all respects, and embodiments of the present invention are not limited thereto. That is, as long as the configuration described in the claims of the present application and a configuration equivalent thereto are provided, a configuration obtained by appropriately modifying a part of the configuration not described in the claims is naturally also included in the present invention. Belongs to the technical scope.

DESCRIPTION OF SYMBOLS 1 Electric power generation system 2 Secondary excitation induction generator 2a Rotor 2b Stator 3 Gas engine 4 Electric power system 5 Power storage device 7 Electric power load 11 First power converter 12 Second power converter 13 DC part 23 Third switch (switching switch) )
100 Control device f1 Output power frequency v1 Primary voltage v2 Secondary voltage

Claims (7)

A secondary excitation induction generator having a stator with a primary winding and a rotor with a secondary winding;
A drive source for driving the rotor;
A first power converter having an AC side connected to the primary winding;
A second power converter having an AC side connected to the secondary winding;
A power storage device connected to a direct current unit connecting the direct current side of the first power converter and the direct current side of the second power converter;
A control method for a power generation system comprising a changeover switch that selectively connects the primary winding and a power load,
As the drive source, an engine with adjustable rotation speed is provided,
The engine is driven at a predetermined target rotational speed, and output power of a desired target frequency is supplied to the power load by power supply from the power storage device without receiving power supply from an external power system. Regarding autonomous operation,
The engine is driven at a no-load rotational speed faster than the target rotational speed in an unloaded state where the changeover switch is open and the primary winding is not connected to the power load, and the primary winding A standby operation step of controlling the output power of the target frequency to the output power of the target frequency,
Then, the control method of the electric power generation system which performs the load connection process which makes the said changeover switch a closed state and connects the said primary winding to the said electric power load.   The no-load rotation speed falls within the target range of the maximum rotation speed of the engine or the output power frequency when the changeover switch is closed from the no-load state and connected to the power load. The method of controlling a power generation system according to claim 1, wherein the control method is set to any one of a rotation speed that is higher than a possible rotation speed and lower than the maximum rotation speed.   When the load factor, which is the ratio of the connected load power of the power load connected to the primary winding to the total power consumed by the power load, is less than the set load factor, according to the increase in the load factor 3. The non-load rotation speed is set to a higher rotation speed, and when the load factor is equal to or higher than the set load factor, the no-load rotation speed is set to the maximum rotation speed of the engine. A method for controlling the power generation system according to claim 1. Regarding the self-sustained operation, before performing the standby operation step, the rotor is driven by the engine in the no-load state, and the primary side excitation step of exciting the primary winding by the first power converter; A primary side having a primary voltage generated on the primary side of the secondary excitation induction generator as a target voltage value, performing both of the secondary side excitation step of exciting the secondary winding by a second power converter Run the voltage establishment process,
The said primary side voltage establishment process WHEREIN: As the said primary side excitation process, the reactive power is supplied to the said primary winding from said 1st power converter, The control method of the electric power generation system as described in any one of Claims 1-3 . The primary side voltage establishing step includes a delay type primary side voltage establishing step of starting the primary side excitation step after executing a step of boosting the primary side voltage to the target voltage value by the secondary side excitation step. And
In the delay type primary side voltage establishing step, after the boosting step, the reactive power supplied from the first power converter to the primary winding is increased in a state where the primary side voltage is maintained at the target voltage value. The power generation system control method according to claim 4, wherein the power supplied from the second power converter to the secondary winding is reduced. A secondary excitation induction generator having a stator with a primary winding and a rotor with a secondary winding;
A drive source for driving the rotor;
A first power converter having an AC side connected to the primary winding;
A second power converter having an AC side connected to the secondary winding;
A power storage device connected to a direct current unit connecting the direct current side of the first power converter and the direct current side of the second power converter;
A control device for a power generation system comprising a changeover switch that selectively connects the primary winding and a power load,
As the drive source, an engine with adjustable rotation speed is provided,
The engine is driven at a predetermined target rotational speed, and output power of a desired target frequency is supplied to the power load by power supply from the power storage device without receiving power supply from an external power system. The self-sustaining operation control unit that performs self-sustaining operation
The engine is driven at a no-load rotational speed faster than the target rotational speed in an unloaded state where the changeover switch is open and the primary winding is not connected to the power load, and the primary winding A standby operation control unit that executes a standby operation step of controlling the output power of the target frequency to the output power of the target frequency;
A control device of a power generation system comprising: a load connection control unit that executes a load connection step of connecting the primary winding to the power load with the changeover switch closed.   Decrease in output power frequency when the standby operation control unit is connected to the power load with the rotation speed at no load, the maximum rotation speed of the engine, or from the no load state with the changeover switch closed. The control device for a power generation system according to claim 6, wherein the standby operation step is executed by setting the rotation speed to any one of a rotation speed that is within a target range and a rotation speed that is less than or equal to the maximum rotation speed.

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