JP2014183708A - Power generating system and operational method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform power supply to a power load while alleviating a burden applied to an engine, when performing autonomous operation that freely supplies electric power to a power load without receiving power supply from a power system.SOLUTION: The autonomous operation includes the following control operations to be performed in order: high speed control for controlling an engine rotational speed to a first rotational speed of a higher rotational speed than a target rotational speed; connection control for connecting a primary winding with a power load through a switching section under a control state of the engine rotational speed to maintain the engine rotational speed at the first rotational speed; rotational speed keeping control for controlling the engine rotational speed to keep the engine rotational speed at the first rotational speed even after the connection control; and target rotational speed control for controlling the engine rotational speed to the target rotational speed.

Description

  The present invention relates to a power generation system including a secondary excitation generator and an engine that drives a rotor of the secondary excitation generator, and an operation method of the power generation system.

  In the power generation system as described above, for example, a secondary excitation generator having a stator having a primary winding connected to the power system and a rotor having a secondary winding, and the AC side is connected to the power system. The first power converter, the second power converter whose AC side is connected to the secondary winding, and the DC unit that connects the DC side of the first power converter and the DC side of the second power converter. The power storage device and a switching unit that can freely connect and disconnect the primary winding and the power load are provided (see, for example, Patent Document 1). Then, the engine rotation speed is set to a constant rotation speed of the target rotation speed, and the AC frequency supplied to the secondary winding of the secondary excitation generator is controlled, so that the constant frequency ( While outputting electric power of 50 [Hz] or 60 [Hz], the engine is operated at a favorable rotational speed from the viewpoint of efficiency to improve power generation efficiency.

  The system described in Patent Document 1 is configured to perform a self-supporting operation that allows power to be freely supplied to an electric power load without being supplied with electric power from an electric power system in order to be used as an emergency power source. Yes. In this self-sustained operation, the output power of the target frequency is supplied to the power load by connecting the primary winding to the power load while the output power of the primary winding is controlled to the output power of the target frequency. .

JP 2012-1000047 A

  In the system described in Patent Document 1, when the primary winding is connected to the power load in the self-supporting operation, the engine speed is controlled to the no-load rotation speed that is higher than the target rotation speed. The primary winding is connected to the power load. As a result, a significant decrease in the engine rotation speed when the power load is connected is suppressed, and fluctuations in the frequency of the output power are suppressed.

  However, in the system described in Patent Document 1, immediately after the primary winding is connected to the power load, the engine rotational speed is set to the target rotational speed lower than the no-load rotational speed and the rotational speed in the vicinity thereof. I try to control it. As described above, when the engine speed is reduced immediately after the power load is connected, the engine speed reduced by the connection of the power load is further reduced, and the torque is increased according to the decrease in the speed. As a result, a heavy burden is placed on the engine.

  The present invention has been made paying attention to such a point, and the purpose of the present invention is to provide the engine with a self-supporting operation in which power can be freely supplied to the power load without receiving power from the power system. An object of the present invention is to provide a power generation system capable of supplying power to a power load while reducing the burden, and a method for operating the power generation system.

In order to achieve this object, the characteristic configuration of the power generation system according to the present invention includes a secondary excitation generator having a stator having a primary winding connected to an electric power system and a rotor having a secondary winding. An engine for driving the rotor, a first power converter whose AC side is connected to the power system, a second power converter whose AC side is connected to the secondary winding, and the first power converter A power storage device connected to a direct current unit connecting the direct current side of the second power converter and the direct current side of the second power converter, a switching unit capable of intermittently connecting the primary winding and the power load, and an operation for controlling the operation A control unit,
The operation control unit drives the engine at a target rotation speed, and supplies output power at a target frequency to the power load by supplying power from the power storage device without receiving power supply from the power system. Self-sustaining operation is possible,
In the self-sustained operation, high rotation speed control is performed to control the engine rotation speed to a first rotation speed that is higher than the target rotation speed, and then the engine rotation speed is maintained at the first rotation speed. In a state where the engine speed is controlled, the switching unit performs connection control for connecting the primary winding and the power load. Next, after the connection control is performed, the engine speed is set to the first speed. The rotational speed maintenance control for controlling the engine rotational speed to be maintained is performed, and then the target rotational speed control for controlling the engine rotational speed to the target rotational speed is performed.

  According to this characteristic configuration, in the connection control, the primary winding and the power load are connected in a state where the engine rotation speed is maintained at the first rotation speed, and then the rotation speed maintenance control is performed. As described above, the engine rotation speed is maintained at the first rotation speed both when the power load is connected and after the connection. Therefore, even if the engine rotation speed decreases due to the connection of the power load, the engine rotation speed is maintained. The amount of decrease in the engine speed can be suppressed, and the engine speed can be prevented from further decreasing after the connection. As a result, an increase in torque associated with a decrease in engine rotation speed can be suppressed, and power can be supplied to the electric power load while reducing the burden on the engine when performing independent operation.

  In a further characteristic configuration of the power generation system according to the present invention, the operation control unit performs the rotation speed maintenance control when a stabilization condition is satisfied that a change in the engine rotation speed after the start of the connection control is stabilized. It is the point which is comprised so that it may complete | finish and may transfer to the said target rotational speed control.

  As described above, after the connection control is performed and before the engine rotation speed is stabilized, when the rotation speed maintenance control is terminated and the target rotation speed control is started, the engine rotation speed is decreased, and the torque is reduced with the decrease. Increases and knocking is likely to occur. Therefore, in this feature configuration, it is assumed that the fluctuation of the engine rotation speed after the start of the connection control is settled in order to end the rotation speed maintenance control and shift to the target rotation speed control while the engine rotation speed is stable. Satisfying the stabilization condition is the transition condition from the rotational speed maintenance control to the target rotational speed control. Thereby, the transition from the rotation speed maintenance control to the target rotation speed control is performed at an appropriate timing, the occurrence of knocking can be suppressed, and the output power of the target frequency to the power load can be smoothly performed.

  According to a further characteristic configuration of the power generation system according to the present invention, the operation control unit does not shift to the target rotational speed control until the output from the primary winding reaches the target output, and the connection control and the The rotational speed maintaining control is repeatedly performed, and when the output from the primary winding reaches the target output, the control is shifted to the target rotational speed control.

  According to this feature configuration, since the connection control and the rotation speed maintenance control are repeatedly performed until the output from the primary winding reaches the target output, the primary winding is suppressed while suppressing the torque increase in each of the repeated connection controls. The output from the line can be increased step by step to the target output. As a result, even when the rated output (for example, 100% output) is achieved in the autonomous operation, the output can be increased to the rated output while reducing the burden on the engine, and the efficiency in the autonomous operation is improved. The load amount of the power load that can be connected can be increased.

A method for operating a power generation system according to the present invention includes a secondary excitation generator having a stator having a primary winding connected to an electric power system and a rotor having a secondary winding, and an engine for driving the rotor. A first power converter having an AC side connected to the power system, a second power converter having an AC side connected to the secondary winding, a DC side of the first power converter, and the second power. In a power generation system including a power storage device connected to a DC unit that connects the DC side of the converter, and a switching unit that can be intermittently connected between the primary winding and the power load,
The engine can be driven at a target rotational speed, and self-sustained operation can be performed to supply output power at a target frequency to the power load by supplying power from the power storage device without receiving power supply from the power system. Yes,
In the self-sustained operation, high rotation speed control is performed to control the engine rotation speed to a first rotation speed that is higher than the target rotation speed, and then the engine rotation speed is maintained at the first rotation speed. In a state where the engine speed is controlled, the switching unit performs connection control for connecting the primary winding and the power load. Next, after the connection control is performed, the engine speed is set to the first speed. The rotational speed maintenance control for controlling the engine rotational speed to be maintained is performed, and then the target rotational speed control for controlling the engine rotational speed to the target rotational speed is performed.

  As in the power generation system according to the present invention described above, the engine rotation speed is maintained at the first rotation speed even when the power load is connected and after the power load connection. Even if the engine speed decreases, the amount of decrease in the engine speed can be suppressed, and the engine speed can be prevented from further decreasing after the connection. As a result, an increase in torque associated with a decrease in engine rotation speed can be suppressed, and power can be supplied to the electric power load while reducing the burden on the engine when performing independent operation.

Diagram showing the overall configuration of the power generation system Flow chart showing operation in autonomous operation A graph showing changes in output, engine speed, and torque in autonomous operation Graph for explaining the transition timing from rotational speed maintenance control to target rotational speed control The graph which shows each change of the output in the self-sustained operation in 2nd Embodiment, an engine speed, and a torque.

An embodiment of a power generation system according to the present invention will be described with reference to the drawings.
[First Embodiment]
As shown in FIG. 1, the power generation system 100 generates electric power supplied to the electric power load 61 by the engine 1 that outputs the rotational power by burning the air-fuel mixture M in the combustion chamber 1 a and the shaft power of the engine 1. The power generation mechanism 101 includes an operation control unit 102 having an engine control unit 102 a that controls the operation of the engine 1 and a power generation mechanism control unit 102 b that controls the operation of the power generation mechanism 101.

(engine)
The engine 1 is configured as a normal four-cycle engine. Connected to the combustion chamber 1a of the engine 1 are an intake passage 3 for sucking the air-fuel mixture M and an exhaust passage 4 through which exhaust gas E discharged from the engine 1 flows. A fuel supply path 9 for supplying a fuel gas G such as a natural gas city gas 13 </ b> A is connected to the intake path 3 via a mixer 8. Combustion air A sucked from an end of the intake passage 3 through an air cleaner (not shown) is mixed with fuel gas G supplied from the fuel supply passage 9 in the mixer 8 to form an air-fuel mixture M. . The mixture M passes through a supercharger (not shown) in the intake passage 3 and is sucked into the combustion chamber 1a. The air-fuel mixture M sucked into the combustion chamber 1a is compressed by the rise of a piston (not shown) and is ignited by a spark plug (not shown) to burn and expand, thereby depressing the piston and outputting the output shaft. 1b rotates and rotational power is output. The exhaust gas E generated by the combustion is pushed out from the combustion chamber 1a to the exhaust passage 4, and is discharged outside after rotating the supercharger. Further, the engine 1 is provided with a rotation speed sensor 1c that detects the rotation speed of the output shaft 1b, that is, the rotation speed of the engine 1. Information detected by the rotation speed sensor 1c is the engine control unit of the operation control unit 102. 102a is configured to be input.

  The intake passage 3 is provided with a throttle valve 6 capable of adjusting the intake amount of the air-fuel mixture M sucked into the combustion chamber 1a. The fuel supply path 9 is provided with a fuel supply valve 10 that can adjust the supply amount of the fuel gas G to the mixer 8. The engine control unit 102a of the control device 70 controls the rotation speed of the engine 1 by controlling the output of the engine 1 in the form of feedback control of the opening of the fuel supply valve 10 based on the detection result of the rotation speed sensor 1c. Output control to set the target set rotational speed is executed.

  In this output control, when the rotational speed of the engine 1 tends to decrease with respect to the set rotational speed, the opening of the fuel supply valve 10 is increased in order to increase the supply amount of the fuel gas G, and then the throttle The air ratio is adjusted by increasing the opening of the valve 6. This increases the output. Conversely, when the rotational speed of the engine 1 tends to increase with respect to the set rotational speed, the opening of the fuel supply valve 10 is reduced in order to reduce the supply amount of the fuel gas G, and then the throttle valve 6 The air ratio is adjusted by reducing the opening. This reduces the output. By such output control, the output of the engine 1 is adjusted, and the rotational speed of the engine 1 is controlled to the set rotational speed.

  The engine control unit 102 a controls the opening degree of the throttle valve 6 based on the opening degree of the fuel supply valve 10. That is, when the opening degree of the fuel supply valve 10 is increased and the flow rate of the fuel gas G flowing through the mixer 8 is increased, the opening degree of the throttle valve 6 is increased, and the combustion air A to the mixer 8 is increased. The supply amount is increased as the flow rate of the fuel gas G increases. Conversely, when the opening of the fuel supply valve 10 is reduced and the flow rate of the fuel gas G flowing through the mixer 8 is reduced, the opening of the throttle valve 6 is reduced and the combustion air A to the mixer 8 is reduced. Is reduced in accordance with the decrease in the flow rate of the fuel gas G. The engine control unit 102a controls the opening degree of the throttle valve 6 so as to adjust the air ratio of the air-fuel mixture M supplied to the engine 1 to a predetermined air ratio. Here, the air ratio is the ratio of the theoretical air amount necessary for fuel combustion to the actual air amount supplied (actual air amount / theoretical air amount). As for the air ratio, for example, the air ratio is obtained based on detection information from sensors such as an oxygen sensor provided in the exhaust passage 4, or the opening of the fuel supply valve 10 and the supply pressure of the supply manifold From this, the air ratio can be obtained.

(Power generation mechanism)
The power generation mechanism 101 generates power supplied to the power system 60 and the power load 61 by the shaft power of the engine 1. The power generation mechanism 101 includes a stator 2b (stator) having a primary winding (not shown) connected to the power system 60 and the power load 61, and a secondary winding (not shown). A secondary excitation generator 2 having a rotor 2a (rotor) rotating by power, a first power converter 31 and a second power converter 32 as power converters for applying an excitation current to the secondary winding; It has.

  The primary winding of the stator 2b is connected to a power system (commercial power system) 60, the AC side of the first power converter 31 is connected to the power system 60, and the AC side of the second power converter 32 is the rotor 2a. And a direct current section 33 that connects the direct current side of the first power converter 31 and the direct current side of the second power converter 32. The secondary excitation generator 2 generates electric power (three-phase AC power) having the same frequency (for example, 50 [Hz] or 60 [Hz]) as the electric power system 60, and uses the electric power to consume electric power. 61 and power system 60 can be supplied. The power load 61 includes, for example, an indoor unit, an outdoor unit, or an electric lamp provided in the air conditioning facility.

  The primary winding provided in the stator 2 b of the secondary excitation generator 2 is connected to the power system 60 via the first switch 41 and the second switch 42. The primary winding included in the stator 2 b is also connected to the power load 61 via the first switch 41 and the third switch 43. The secondary winding included in the rotor 2a is passed through the filter circuit 30, the second power converter 32, the DC unit 33, the first power converter 31, the filter circuit 30, the transformer 44, and the second switch 42. The power system 60 is connected. Further, the secondary winding included in the rotor 2 a passes through the filter circuit 30, the second power converter 32, the DC unit 33, the first power converter 31, the filter circuit 30, the transformer 44, and the third switch 43. The power load 61 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 generator", and the secondary winding side included in the rotor 2a is referred to as "secondary side of the secondary excitation generator". Sometimes called. Therefore, the frequency of power (voltage, current) generated on the primary side of the secondary excitation generator 2 is the frequency of power supplied to the power load 61 and the power system 60.

  The output shaft 1b of the engine 1 is mechanically connected to the rotor 2a of the secondary excitation generator 2, and drives (rotates) the rotor 2a. In this example, the output shaft 1b of the engine 1 is connected (directly connected) so as to rotate integrally with the rotor 2a, and the rotor 2a rotates at the same rotational speed as the engine rotational speed. In addition, it can also be set as the structure which provides a reduction gear and a speed up gear between the output shaft 1b of the engine 1, and the rotor 2a.

  The first power converter 31 is connected to the stator 2b (primary winding) of the secondary excitation generator 2 via the first switch 41 on the AC side (the right side in FIG. 1), and the second switch 42. Is connected to the electric power system 60 via the third switch 43, and is further connected to the electric power load 61 via the third switch 43. The first power converter 31 is connected to the DC unit 33 on the DC side (left side in FIG. 1). The second power converter 32 is connected to the rotor 2a (secondary winding) of the secondary excitation generator 2 on the AC side (left side in FIG. 1). Further, the second power converter 32 has a DC side (right side in FIG. 1) connected to the DC unit 33. Each of the first power converter 31 and the second power converter 32 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 31 and the second power converter 32 are configured to include a plurality of (for example, six) switching elements. As the switching element, power transistors having various structures such as a MOSFET (Metal Oxide Field Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor) can be adopted. Then, a PWM (pulse width modulation) signal is input to the first power converter 31 and the second power converter 32, 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 31 and the second power converter 32 is generated by the power generation mechanism control unit 102b.

  A filter circuit 30 including an inductance and a capacitor is provided on both the AC side of the first power converter 31 and the AC side of the second power converter 32. The filter circuit 30 is a filter that removes a high-frequency component generated by switching of the switching element, and the output voltage waveform from the first power converter 31 and the second power converter 32 is sinusoidal by the filter circuit 30. Converted.

  A transformer 44 is provided on the secondary excitation generator 2 side (power system 60 side) from the filter circuit 30 provided on the AC side of the first power converter 31. In the following description, “the primary side of the transformer” refers to the first power converter 31 side of the transformer 44, and “the secondary side of the transformer” refers to the secondary excitation generator 2 side of the transformer 44. Point to.

  The DC unit 33 is a part that connects the DC side of the first power converter 31 and the DC side of the second power converter 32. The DC unit 33 includes a capacitor 34 and is connected to a power storage device 62. The power storage device 62 is capable of supplying power necessary for starting the power generation mechanism unit 101. It is also possible to suppress fluctuations in power supplied to the power load 61 and the power grid 60 using the power storage device 62. The power storage device 62 is composed of, for example, a storage battery, an electric double layer capacitor, or the like, and can supply and discharge power to the DC unit 33 and can be charged by receiving power from the DC unit 33 and charging. Configured. A switch may be interposed between the power storage device 62 and the DC unit 33.

  The first switch 41 selectively connects the stator 2 b (primary winding) of the secondary excitation generator 2 and the first power converter 31. The second switch 42 selectively connects the power system 60 and the first power converter 31. The first switch 41 cooperates with the second switch 42 to selectively connect the stator 2b (primary winding) of the secondary excitation generator 2 and the power system 60 and to cooperate with the third switch 43. The stator 2b (primary winding) of the secondary excitation generator 2 and the power load 61 are selectively connected. In addition, the second switch 42 cooperates with the third switch 43 to selectively connect the power system 60 and the power load 61.

  Each of the first switch 41, the second switch 42, and the third switch 43 is controlled to open / close based on an open / close signal generated by the power generation mechanism control unit 102b. These switches can be, for example, electromagnetic contact type switches that open and close by the operation of an electromagnet.

  The power generation mechanism unit 101 is a system having a high degree of freedom with respect to the frequency (voltage, current frequency) of the generated power. The frequency of the power generated by the power generation mechanism 101 (the frequency of the primary voltage induced on the primary side of the secondary excitation generator 2) is f1, the rotation frequency of the rotor 2a is f0, and the secondary winding of the rotor 2a. When the frequency of the alternating current (excitation current) supplied to the secondary winding for exciting the wire is f2, “f1 = f0 + f2”. Here, the rotational frequency f0 of the rotor 2a is “f0 = m × n / 120, where the rotational speed (number of rotations) of the rotor 2a is m [rpm] and the number of magnetic poles of the secondary excitation generator 2 is n. ”

  Specifically, when the rotation speed of the rotor 2a is 1100 [rpm] and the number of magnetic poles of the secondary excitation generator 2 is “6”, the rotation frequency f0 of the rotor 2a is 55 [Hz]. Become. Therefore, in this case, if the second power converter 32 is controlled to supply an excitation current having a frequency of 5 [Hz] to the secondary winding (f2 = 5 [Hz]), the frequency is 60 [Hz]. AC power can be obtained. Conversely, if the second power converter 32 is controlled to extract an excitation current having a frequency of 5 [Hz] from the secondary winding (f2 = −5 [Hz]), AC power having a frequency of 50 [Hz] is obtained. 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 engine rotation speed). The synchronous rotation speed is 1200 [rpm] when the frequency of the power system 60 is 60 [Hz] and the number of magnetic poles of the secondary excitation generator 2 is “6”.

  Even if the rotation speed of the rotor 2a (that is, the engine rotation speed) is the same, the frequency f1 of the generated power is changed by changing the frequency f2 and direction of the excitation current supplied to the secondary winding of the rotor 2a. Can do. That is, the power generation mechanism control unit 102b controls the frequency and direction of the excitation current applied to the secondary winding to synchronize the frequency of the output power (ie, generated power) of the primary winding with the power system 60. Is configured to run. The direction of the excitation current between the second power converter 32 and the secondary winding of the rotor 2a is the same as the supply direction X when the excitation current is supplied from the second power converter 32 to the secondary winding. , And switching from the extraction direction Y when the excitation current is extracted from the secondary winding to the second power converter 32. Therefore, even if the rotation speed of the engine 1 fluctuates, the second power converter 32 is controlled to excite the frequency corresponding to the shortage (or excess) of the rotation speed of the rotor 2a with respect to the frequency of the power system 60. By supplying current to the secondary winding of the secondary excitation generator 2 (or taking out from the secondary winding), generated power having the same frequency as the frequency of the power system 60 is taken out from the first power converter 31. become.

  The operation of the power generation system 100 is controlled by the operation control unit 102, and the stator 2 b (primary winding) of the secondary excitation generator 2, the power load 61, and the power system 60 are controlled by the first to third switches 41 to 43. And the engine 1 is driven at a target rotational speed (for example, 1200 [rpm]), and an output power supply operation for supplying output power at a target frequency to the power system 60 and the power load 61 is performed. . In this output power supply operation, the engine control unit 102a in the operation control unit 102 sets the set rotational speed as a control target to a target rotational speed (for example, 1200 [rpm]), and drives the engine 1 at the target rotational speed. The power generation mechanism control unit 102b in the operation control unit 102 controls the frequency and direction of the excitation current applied to the secondary winding so that the frequency of the generated power is set to the target frequency (for example, 50 [Hz ] And 60 [Hz]). By performing such output control and synchronous control, the generated power is set to the same frequency as the frequency of the power grid 60 and the power load 61. In this state, the power generation mechanism control unit 102b performs the second and third switches 42, By closing 43, the stator 2b (primary winding) of the secondary excitation generator 2 is connected to the power system 60 and the power load 61, and the target frequency (the same as the frequency of the power system 60 and the power load 61) is connected. Frequency) generated power is supplied to the power system 60 and the power load 61.

  In this power generation system 100, the engine 1 is driven at a target rotational speed (for example, 1200 [rpm]) so that it can also be used as an emergency power source, and power is not supplied from the power system 60. It is configured to perform a self-supporting operation that allows power to be freely supplied to the load 61.

Hereinafter, the independent operation will be described.
As shown in FIG. 2, the operation control unit 102 first controls the engine rotation speed to a first rotation speed (for example, 1500 [rpm]) that is higher than the target rotation speed (for example, 1200 [rpm]). High rotation speed control is performed (step # 1). In this high rotation speed control, the engine control unit 102a sets the set rotation speed as a control target to the first rotation speed (for example, 1500 [rpm]), and sets the engine rotation speed to the first rotation speed (for example, 1500 [rpm]). ) To control the output so that the engine 1 is driven. Further, the power generation mechanism control unit 102b controls the frequency and direction of the excitation current applied to the secondary winding to synchronize the frequency of the generated power with a target frequency (for example, 50 [Hz] or 60 [Hz]). Performs synchronous control. In this high rotation speed control, the power generation mechanism control unit 102b controls the second and third switches 42 and 43 to open, and the stator 2b (primary winding) of the secondary excitation generator 2 and the power system 60 or The power load 61 is not connected and is in a no-load state.

  Next, the operation control unit 102 fixes the secondary excitation generator 2 by the third switch 43 (corresponding to the switching unit) in a state where the engine rotation speed is controlled so as to maintain the engine rotation speed at the first rotation speed. Connection control for connecting the child 2b (primary winding) and the power load 61 is performed (step # 2). In this connection control, the engine control unit 102a performs output control so as to drive the engine 1 by controlling the engine rotational speed to the first rotational speed (for example, 1500 [rpm]), similarly to the high rotational speed control. . Further, the power generation mechanism control unit 102b controls the third switch 43 to be closed so that the load amount of the power load 61 to be connected becomes the set load amount, and the stator 2b (primary winding) of the secondary excitation generator 2 And the power load 61 are connected. That is, the power generation mechanism control unit 102b controls the third switch 43 to close so that the output from the power generation mechanism unit 101 becomes the target output, and the stator 2b (primary winding) of the secondary excitation generator 2 and the power A load 61 is connected.

  Next, the operation control unit 102 performs rotational speed maintenance control for controlling the engine rotational speed so as to maintain the engine rotational speed at the first rotational speed even after performing the connection control described above (step # 3). In this rotational speed maintenance control, similarly to the high rotational speed control, the engine control unit 102a performs output control so as to drive the engine 1 by controlling the engine rotational speed to the first rotational speed (for example, 1500 [rpm]). I do. Further, the power generation mechanism control unit 102b controls the frequency and direction of the excitation current applied to the secondary winding to synchronize the frequency of the generated power with a target frequency (for example, 50 [Hz] or 60 [Hz]). Performs synchronous control.

  Next, the operation control unit 102 performs target rotation speed control for controlling the engine rotation speed to the target rotation speed (step # 4). In this target rotation speed control, the engine control unit 102a drives the engine 1 by setting the set rotation speed as a control target as the target rotation speed and controlling the engine rotation speed to the target rotation speed (for example, 1200 [rpm]). The output is controlled as follows. Further, the power generation mechanism control unit 102b controls the frequency and direction of the excitation current applied to the secondary winding to synchronize the frequency of the generated power with a target frequency (for example, 50 [Hz] or 60 [Hz]). Performs synchronous control.

  Hereinafter, based on FIG. 3, how the output (output power) from the power generation mechanism unit 101, the engine rotation speed in the engine 1, and the torque in the engine 1 change by performing each control of the above-described self-sustained operation. Will be described. 3 (a) shows the output (power generation output) P1, FIG. 3 (b) shows the engine speed in this embodiment, and FIG. 3 (c) shows the torque T1. FIG. 3D shows the engine speed in the comparative example.

  Further, for the comparative example, FIG. 3 shows not only the engine rotation speed but also changes in output and torque. In this comparative example, in the connection control, immediately after connecting the stator 2b (primary winding) of the secondary excitation generator 2 and the power load 61, the engine rotation speed is set to the target rotation speed (for example, 1200 [rpm]). I try to control it. The output P2 in this comparative example is indicated by a dotted line in FIG. 3A, the engine speed is indicated in FIG. 3D, and the torque T2 is indicated by a dotted line in FIG. 3C. Is shown.

  In FIG. 3, the target output in the connection control is 60% of the total, and the set load amount of the power load 61 connected to the stator 2 b (primary winding) of the secondary excitation generator 2 is the same as that of the entire power load 61. 60%. The target rotation speed is 1200 [rpm], and the first rotation speed is 1500 [rpm]. 3 (b) and 3 (d), the actual engine speed N1 is indicated by a solid line, and the engine speed (the target speed 1200 [rpm] or A rotation speed of 1500 [rpm]) N2 is indicated by a dotted line.

  In the comparative example, as shown in FIG. 3 (d), by connecting the stator 2b (primary winding) of the secondary excitation generator 2 to the power load 61, the engine rotation speed decreases, and immediately after the connection. Since the engine rotation speed is controlled to a target rotation speed (for example, 1200 [rpm]), the engine rotation speed is further reduced. As a result, in the comparative example, as indicated by the dotted line T2 in FIG. 3C, the torque increases due to the decrease in the engine rotation speed, the increased torque continues for a long time, and the engine 1 is burdened heavily. It will take. Further, as indicated by the dotted line P2 in FIG. 3A, the time until the output reaches 60%, which is the target output, is longer, and the time required to turn on the power load is longer.

  On the other hand, in this embodiment, as shown by the solid line N1 in FIG. 3B, in the connection control, the stator 2b (primary winding) of the secondary excitation generator 2 is connected to the power load 61. Although the engine rotation speed is once reduced, the engine rotation speed is controlled to 1500 [rpm] which is the first rotation speed by the connection control and the subsequent rotation speed maintenance control. The amount of decrease is kept small. As the time elapses, the engine rotation speed increases, and the engine rotation speed is maintained at 1500 [rpm] which is the first rotation speed. As indicated by the solid line T1 in FIG. 3C, although the torque also increases due to a decrease in the engine rotation speed, the increase amount can be suppressed smaller than the dotted line T2, which is a comparative example. By maintaining the state in which the engine is kept small, it is possible to prevent a heavy burden on the engine 1. Also, as indicated by the solid line P1 in FIG. 3A, the time until the output reaches the target output of 60% is shorter than the dotted line P2 which is the comparative example, and the power load 61 is turned on. It is possible to shorten the time required to do this.

  Here, based on FIG. 4, the timing at which the transition from the rotation speed maintenance control to the target rotation speed control is performed will be described. 4A shows the change in output, FIG. 4B shows the change in engine speed, and FIG. 4C shows the mixing supplied to the engine 1. The change in the air ratio of the gas M is shown. In FIG. 4, the stator 2 b (primary winding) of the secondary excitation generator 2 is connected to the power load 61 under the condition that the engine rotation speed is controlled to 1200 [rpm] which is the target rotation speed. This shows the case where the engine speed is controlled to 1200 [rpm] which is the target speed even after connection.

  As shown in FIG. 4B, when the stator 2b (primary winding) of the secondary excitation generator 2 is connected to the power load 61 (from the start of connection of T1 in FIG. 4), the engine speed Therefore, the engine control unit 102a controls the opening degree of the fuel supply valve 10 to increase the supply amount of the fuel gas G, and then increases the opening degree of the throttle valve 6 in order to increase the engine rotation speed. Control and adjust the air ratio. Thereby, as shown in FIG.4 (c), an air ratio falls rapidly. And, as shown in FIGS. 4B and 4C, the stabilization time required for the air ratio to settle in the vicinity of the air ratio at the connection start time (T1) is as follows. It is substantially the same as the stabilization time required for stabilization in the vicinity of the engine speed of T1).

  Therefore, in this embodiment, when the operation control unit 102 satisfies the stabilization condition that the fluctuation of the engine rotation speed after the start of the connection control is stabilized, the rotation speed maintenance control is terminated and the target rotation speed control is performed. Configured to migrate. As for the stabilization condition, for example, a stabilization range (for example, engine rotation speed ± 20 [rpm] at the start of connection control) is set based on the engine rotation speed at the start of connection control. It is possible to determine that the stabilization condition is satisfied when the engine rotation speed of the engine falls within the stabilization range, or when the state within the stabilization range continues for the set time. Further, for example, a settling time required until the fluctuation of the engine rotation speed after the start of connection control is settled is set by experiment, and the settling time elapses after the start of connection control. It can also be determined that the constant condition is satisfied.

  As described above, the operation control unit 102 ends the rotation speed maintenance control and shifts to the target rotation speed control when the stabilization condition that the fluctuation of the engine rotation speed after the start of the connection control is stabilized is satisfied. However, for example, when the air ratio stabilization condition that the air ratio of the engine 1 after the start of the connection control is stabilized is satisfied, the rotation speed maintenance control is terminated and the process proceeds to the target rotation speed control. You can also As for the static condition for the air ratio at this time, similarly to the static condition described above, for example, a static range based on the air ratio at the start of connection control is set, and the air after the start of connection control is set. When the ratio falls within the settling range, or when the state within the settling range continues for the set time, it can be determined that the settling conditions for the air ratio are satisfied. In addition, for example, a settling time required until the fluctuation of the air ratio after the start of connection control is settled is set by experiment, and the settling time after the start of connection control elapses. It can also be determined that the static settling condition for use is satisfied.

[Second Embodiment]
In the said 1st Embodiment, it transfers to target rotational speed control by performing connection control and rotational speed maintenance control once. In the second embodiment, as shown in FIG. 5, the operation control unit 102 performs the target rotation until the output from the stator 2b (primary winding) of the secondary excitation generator 2 reaches the target output in the independent operation. Without shifting to the speed control, the connection control and the rotation speed maintenance control are repeated, and when the output from the stator 2b (primary winding) of the secondary excitation generator 2 reaches the target output in the self-sustaining operation, the target rotation Shift to speed control.

  In FIG. 5, the target output in the independent operation is a rated output of 100% output. Therefore, the operation control unit 102 first performs the first connection control with the target output in the connection control set to 60%, performs the second connection control with the target output in the connection control set to 100%, and increases the output stepwise. I am doing so. FIG. 5A shows the output (power generation output), FIG. 5B shows the engine rotation speed, and FIG. 5C shows the torque. In FIG. 5B, the actual engine rotation speed N1 is shown by a solid line, and the engine rotation speed (the target rotation speed is 1200 [rpm] or the first rotation speed is 1500, which is the set rotation speed of the control target. [Rpm]) N2 is indicated by a dotted line.

  The operation control unit 102 first performs high rotation speed control, then performs first connection control, and then performs first rotation speed maintenance control. Then, the operation control unit 102 performs the second connection control, performs the second rotation speed maintenance control, and finally performs the target rotation speed control. At this time, with respect to the timing at which the first rotation speed control is finished and the second connection control is started, the fluctuation of the engine rotation speed after the start of the connection control is stabilized as in the first embodiment. When the fixed condition is satisfied, the first rotation speed control can be terminated and the second connection control can be performed.

  As described above, when rated output (for example, 100% output) is performed in the independent operation, the load on the engine 1 can be reduced while increasing the output to the rated output step by step, and the efficiency in the independent operation can be reduced. The load amount of the power load 61 that can be connected can be increased while improving.

  In this embodiment, the target output in the second connection control is set to 100%, and finally the rated output operation is performed. However, the target output in the second connection control is a value lower than 100%. Can also be set. Furthermore, the connection control and the rotation speed maintenance control are performed twice, but for example, the first connection control is performed with the target output set to 30%, and the second connection control is performed with the target output set to 60%. The third connection control can be performed with the target output as 100%, and the number of times of performing the connection control and the rotation speed maintenance control can be changed as appropriate, and may be a plurality of times.

  The present invention provides a secondary excitation generator having a stator having a primary winding connected to an electric power system and a rotor having a secondary winding, an engine for driving the rotor, and an AC side of the electric power system A first power converter connected to the second power converter, a second power converter whose AC side is connected to the secondary winding, a DC side of the first power converter, and a DC side of the second power converter. A power storage device connected to a DC unit to be connected; and a switching unit capable of intermittently connecting and disconnecting the primary winding and the power load, and supplying power to the power load without receiving power from the power system. It is possible to adapt to various power generation systems that can supply power to the power load and various operation methods of the power generation system while reducing the burden on the engine when performing independent operation to make it freely available. is there.

DESCRIPTION OF SYMBOLS 1: Engine 2: Secondary excitation generator 2a: Rotor 2b: Stator 31: 1st power converter 32: 2nd power converter 33: DC part 43: 3rd switch (switching part)
60: Power system 61: Power load 62: Power storage device 102: Operation control unit

Claims (4)

A secondary excitation generator having a stator with a primary winding connected to the power system and a rotor with a secondary winding, an engine for driving the rotor, and an AC side connected to the power system A first power converter, a second power converter whose AC side is connected to the secondary winding, and a DC unit that connects the DC side of the first power converter and the DC side of the second power converter A power storage device connected to the power supply, a switching unit that can freely connect and disconnect the primary winding and the power load, and an operation control unit that controls the operation,
The operation control unit drives the engine at a target rotation speed, and supplies output power at a target frequency to the power load by supplying power from the power storage device without receiving power supply from the power system. Self-sustaining operation is possible,
In the self-sustained operation, high rotation speed control is performed to control the engine rotation speed to a first rotation speed that is higher than the target rotation speed, and then the engine rotation speed is maintained at the first rotation speed. In a state where the engine speed is controlled, the switching unit performs connection control for connecting the primary winding and the power load. Next, after the connection control is performed, the engine speed is set to the first speed. A power generation system configured to perform rotation speed maintenance control for controlling the engine rotation speed so as to be maintained, and then to perform target rotation speed control for controlling the engine rotation speed to the target rotation speed.   The operation control unit finishes the rotation speed maintenance control and shifts to the target rotation speed control when a stabilization condition is satisfied that the fluctuation of the engine rotation speed after the start of the connection control is stabilized. The power generation system according to claim 1 configured.   The operation control unit repeatedly performs the connection control and the rotation speed maintenance control without shifting to the target rotation speed control until the output from the primary winding reaches a target output, The power generation system according to claim 1, wherein when the output reaches a target output, the target rotational speed control is shifted to. A secondary excitation generator having a stator with a primary winding connected to the power system and a rotor with a secondary winding, an engine for driving the rotor, and an AC side connected to the power system A first power converter, a second power converter whose AC side is connected to the secondary winding, and a DC unit that connects the DC side of the first power converter and the DC side of the second power converter In a power generation system including a power storage device connected to the power supply, and a switching unit that can freely connect and disconnect the primary winding and the power load,
The engine can be driven at a target rotational speed, and self-sustained operation can be performed to supply output power at a target frequency to the power load by supplying power from the power storage device without receiving power supply from the power system. Yes,
In the self-sustained operation, high rotation speed control is performed to control the engine rotation speed to a first rotation speed that is higher than the target rotation speed, and then the engine rotation speed is maintained at the first rotation speed. In a state where the engine speed is controlled, the switching unit performs connection control for connecting the primary winding and the power load. Next, after the connection control is performed, the engine speed is set to the first speed. An operation method of a power generation system that performs rotation speed maintenance control for controlling the engine rotation speed so as to maintain, and then performs target rotation speed control for controlling the engine rotation speed to the target rotation speed.

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