JP6424639B2 - Stand-alone operation device of small hydropower variable speed power generation system - Google Patents

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a self-sustaining device for a small hydro-power variable-speed power generation system, and more particularly to a self-sustaining device capable of coping with load fluctuations during self-sustaining operation.

  FIG. 5 shows a single connection diagram of a small hydraulic variable speed power generation system using a permanent magnet synchronous generator, and the small hydraulic power variable speed generation system is connected to the electric power system through an interconnection transformer 14. Ru. In FIG. 5, 1 is a water wheel, 2 is a flywheel, 3 is a permanent magnet synchronous generator, and these are connected via bearings (not shown). The flywheel 2 is not an essential component, and a system without the flywheel 2 is generally used.

  A converter 4 includes a generator control inverter 5, a grid connection control inverter 6, and a DC capacitor 7 connected to a DC circuit between the inverters 5 and 6, a chopper unit 8 and a braking resistor. It has a braking unit consisting of nine. Reference numeral 10 denotes a filter, which includes a reactor L, a capacitor C, and a resistor R. 11 is an electromagnetic switch connected to the generator side, 12 is an electromagnetic switch connected to the system side, 13 is a load, and 15 is a higher-order control unit. This control unit 15 instructs the converter device 4 to operate Signal transmission and reception, as well as adjusting the flow rate of the water turbine via the flow rate adjusting means 16. In addition, as a flow volume adjustment means 16, a governor is made into an example below.

  Converter device 4 usually performs an interconnection operation with a power system. During the linked operation, the generator control inverter 5 performs generator speed (torque) control ASR for controlling the speed or torque of the permanent magnet synchronous generator 3 and alternating current control ACR. The grid interconnection control inverter 6 performs DC voltage (voltage of DC capacitor 7) control AVR and AC current control ACR.

  FIG. 6 shows a state of the small hydro-power variable-speed power generation system shown in FIG. During an interconnection operation, when an abnormality occurs in the interconnection, the electromagnetic switch installed between the interconnection transformer 14 and the load 13 is opened to disconnect the electric power system and the load, and the converter is detected by the interconnection connection failure detection. The device 4 sends failure information to the host control unit 15, and the converter device 4 stops its operation. At this time, by turning on the switching element of the chopper unit 8, a current is supplied to the braking resistor 9 to consume the energy output from the permanent magnet synchronous generator 3.

When the host control unit 15 receives the failure information from the converter device 4, the control device 15 transmits a self-sustaining operation command to the converter device 4, and the converter device 4 performs a switching operation to the self-sustaining operation based on this command. That is, from the generator ASR and AC current control ACR control to DC voltage constant control AVR at the time of grid connection operation, and the grid connection control inverter 6 from DC voltage constant control AVR and AC current control ACR. Each control mode is switched to AC voltage constant control AVR. Thereby, a desired alternating current output voltage is supplied to the load 13 to realize a self-sustaining operation.
In addition, patent document 1 and patent document 2 are known as a self sustaining method of a power generation system.

Japanese Patent Application Publication No. 2014-158371 Japanese Patent Application Laid-Open No. 2002-135979

  The output of the water turbine 1 is approximately proportional to the flow rate. Further, the output power of the permanent magnet synchronous generator 3 is substantially proportional to the axial output of the water turbine 1. Furthermore, the output power current of the converter device 4 depends on the consumption state of the load 13 during the independent operation. From this, if the flow rate adjustment is not appropriate when the load changes, an imbalance occurs between the output power of the permanent magnet synchronous generator 3 and the power to be supplied to the load 13. Due to this, there is a problem that the supply voltage to the load decreases, that is, the output power of the converter 4 decreases, and the generator speed becomes unstable.

  An object of the present invention is to provide a self-sustaining device for a small hydro-power variable-speed power generation system that enables stable operation of the system.

The present invention connects a permanent magnet synchronous generator connected with a water turbine to a power system via a converter device having a generator control inverter and a grid connection control inverter,
Small hydraulic power variable speed power generation equipped with a control unit as a superordinate control system of the converter device to exchange information between the converter device and the control unit, and adjust the flow rate adjusting means by the control unit to adjust the flow rate to the water wheel In this small hydro-power variable-speed power generation system having a self-sustaining operation function,
The converter device is provided with a control block for adjusting the flow rate acting on the independent operation;
The control block generates an operation amount command value of the flow rate adjusting means based on the difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet,
The converter device transmits the generated operation amount command value to the control unit, and the control unit is configured to adjust the flow rate of the water wheel via the flow rate adjusting means based on the operation amount command value. Stand-alone operation device of small hydropower variable speed power generation system.

The control block of the present invention is a first PI controller that generates a flow rate command value by inputting the difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet;
A second PI controller is provided to generate an operation amount command value of the flow rate adjusting means by inputting the difference between the flow rate command value generated by the first PI controller and the flow rate detection value of the water wheel A self-sustaining device for a small hydro-power variable-speed power generation system according to claim 1, wherein

Further, the control block of the present invention is a first PI controller which generates a generator output power command value by inputting the difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet;
The difference between the generator output power command value generated by the first PI controller and the generator output power detection value of the permanent magnet synchronous generator is input to generate the operation amount command value of the flow rate adjusting unit And a PI controller.

  The present invention is characterized in that a flywheel is connected between a water turbine and a permanent magnet synchronous generator.

Moreover, the flywheel of the present invention, the maximum power output speed n ₀ or more speed ranges on efficiency characteristic curve of the water wheel, it is characterized in that it has a inertia to respond to an increase or decrease of the load.

  As described above, according to the present invention, stable power can be supplied to the load even when the load fluctuates at the time of the independent operation. In addition, the speed of the water turbine and the permanent magnet synchronous generator can be stabilized, and stable operation of the small hydraulic power variable speed power generation system becomes possible.

FIG. 2 is a control block diagram for flow rate adjustment showing an embodiment of the present invention. The control block diagram for flow volume adjustment which shows other embodiment of this invention. Explanatory drawing of the energy state at the time of a self sustaining load fluctuation. Efficiency characteristic curve of water turbine. The block diagram of the small hydropower variable-speed power generation system. Explanatory drawing at the time of the independent operation of a small hydropower variable-speed power generation system.

According to the present invention, a converter block is provided with a control block for flow rate adjustment that acts during a self-sustaining operation. The control block inputs the difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet to generate a flow rate command value, and the difference between the generated flow rate command value and the flow rate detection value of the water turbine And a second PI controller which generates an operation amount command value of the flow rate adjusting means. The converter device transmits the generated operation amount command value to the upper control unit, and the control unit adjusts the flow rate of the water wheel through the flow rate adjusting means based on the operation amount command value, and the description will be made based on the following figures. Do.

FIG. 1 shows the control block of the flow regulation according to the invention, which control block of the flow regulation is installed in the converter device 4. As described above, during the independent operation of the small hydraulic power variable speed power generation system, the generator control inverter 5 is operated in the control mode of the direct current voltage control AVR. The subtraction unit 20 obtains the difference between the DC voltage command value Vdc ^* at that time and the DC voltage detection value Vdcdet, inputs the difference to the first PI controller 21, and performs proportional integration operation in the PI controller 21. Here, the DC voltage command value Vdc ^* is set to a value at which the AC output voltage from the grid interconnection control inverter 6 can be output to a desired value.
The desired AC output voltage in this case is generally equal to the voltage of the power system. If control can be made to the DC voltage command value Vdc ^* = DC voltage detection value Vdcdet, the grid interconnection control inverter 6 is controlled via the inverter control circuit (not shown) to supply a desired AC output voltage to the load 13 Is possible.

  On the other hand, the proportional integral value by the PI controller 21 is input to the subtraction unit 22 as a flow rate command value, and the difference from the flow rate detection value is obtained. The flow rate detection value is detected by a flow meter installed in the flow path of the water turbine 1, and the detection value is input to the subtraction unit 22 as a flow rate detection value to calculate the difference from the flow rate command value. The difference is input to the second PI controller 23, and the governor operation amount command value is calculated. The governor operation amount command value is transmitted from the converter device 4 to the upper control unit 15. The control unit 15 controls the opening degree of the governor 16 in accordance with the governor operation amount command value to adjust the flow rate of the water wheel 1.

In the control block of flow rate adjustment shown in FIG. 1, when the load 13 increases rapidly during the stand-alone operation, the output power of the permanent magnet synchronous generator 3 becomes <(power required by the load), and the DC voltage detection value Vdcdet is the DC voltage command Reduce to less than the value Vdc ^* . In this case, the first PI controller 21 raises the flow rate command value according to the difference of the subtraction unit 20. The flow rate increases by outputting the governor operation amount command value in the direction to increase the opening degree of the governor 16 by the operation of the second PI controller 23 by the increase of the flow rate command value, and the output of the water turbine 1 and permanent The output power of the magnet synchronous generator 3 can be raised.

  Therefore, according to this embodiment, the power required by the load can be supplied from the permanent magnet synchronous generator 3, and the generator speed is also stabilized, so that stable operation of the system is possible.

  FIG. 2 shows a control block of flow rate adjustment according to a second embodiment of the present invention, where the same or corresponding parts as in FIG. That is, the difference from FIG. 1 is that the first PI controller 21 becomes a generator output power command value, and the signal input to the subtraction unit 22 becomes a generator output power detection value. The generator output power detection value is obtained by installing a power meter at the output of the permanent magnet synchronous generator 3 or the like.

In this embodiment, when the load 13 increases rapidly during the stand-alone operation, the output power of the permanent magnet synchronous generator 3 becomes <(power required by the load), and the DC voltage detection value Vdcdet is less than the DC voltage command value Vdc ^* The difference of the subtraction part 20 becomes large, and the 1st PI controller 21 raises generator output electric power command value. Furthermore, the flow rate is increased by outputting the governor operation amount command value in the direction to increase the opening degree of the governor 16 by the operation of the second PI controller 23, and the output of the water turbine 1 and the output of the permanent magnet synchronous generator 3 Power can be raised.

  Therefore, in the second embodiment as well as in the first embodiment, the power required by the load can be supplied from the permanent magnet synchronous generator 3, and the generator speed is also stabilized. It is possible.

In the third embodiment, a flywheel 2 is connected between a water turbine 1 and a permanent magnet synchronous generator 3. FIG. 3 is an explanatory view of an energy state at the time of a self-sustaining load change, where (a) shows an increase in load and (b) shows a decrease in load.
Since the variable speed control of the generator speed is not performed during the stand-alone operation of the small hydraulic power generation system, the speed of the permanent magnet synchronous generator 3 changes according to the balance between the generated energy of the water turbine output and the consumed energy of the load 13 .

  As shown in FIG. 3, when a response delay occurs due to opening and closing of the governor 16 during stand-alone operation, power generation is performed during the response time of the governor 16 as shown by the phenomena of load increase (a) and load decrease (b). It is feared that the balance between the output and the load power consumption may break down and the generator speed may become unstable. Therefore, in this embodiment, the flywheel 2 having inertia to compensate for the load fluctuation is connected between the water turbine 1 and the permanent magnet synchronous generator 3.

FIG. 4 shows the efficiency characteristic curve of the water turbine, for example, when the load is increased and the load is within the speed range surrounded by the dotted line above the maximum power generation output speed n ₀ using the efficiency characteristic curve at 100% opening. The inertia of the flywheel 2 is compensated so that the self-sustaining operation corresponding to the decrease can be performed, and the speed instability of the permanent magnet synchronous generator 3 at the time of load change is prevented.

  In this embodiment, it can be carried out when the load shortage / excess electric energy and the kinetic energy generated from the speed deviation at the time of load fluctuation are balanced. The inertia of the flywheel 2 required for that purpose sets the rising / falling limiting speed (Fig. 3 (a), (b)) from the reference speed, obtains kinetic energy from the speed deviation and governor response time, The flywheel 2 is connected to the water turbine 1 and the permanent magnet synchronous generator 3.

  Therefore, according to this embodiment, stable operation of the system can be further improved as compared with Embodiments 1 and 2.

DESCRIPTION OF SYMBOLS 1 ... Water wheel 2 ... Flywheel 3 ... Permanent magnet synchronous generator 4 ... Converter apparatus 5 ... Generator control inverter 6 ... Grid connection control inverter 15 ... Control part 16 ... Flow control means 20, 22 ... Subtraction part 21, 23 ... PI calculator

Claims (5)

Connecting a permanent magnet synchronous generator connected to the water turbine to the electric power system via a converter device having a generator control inverter and a grid connection control inverter,
Small hydraulic power variable speed power generation equipped with a control unit as a superordinate control system of the converter device to exchange information between the converter device and the control unit, and adjust the flow rate adjusting means by the control unit to adjust the flow rate to the water wheel In this small hydro-power variable-speed power generation system having a self-sustaining operation function,
The converter device is provided with a control block for adjusting the flow rate acting on the independent operation;
The control block generates an operation amount command value of the flow rate adjusting means based on the difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet,
The converter device transmits the generated operation amount command value to the control unit, and the control unit is configured to adjust the flow rate of the water wheel via the flow rate adjusting means based on the operation amount command value. Stand-alone operation device of small hydropower variable speed power generation system. The control block is configured to generate a flow rate command value by inputting a difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet;
A second PI controller is provided to generate an operation amount command value of the flow rate adjusting means by inputting the difference between the flow rate command value generated by the first PI controller and the flow rate detection value of the water wheel 2. A self-sustaining device for a small hydro-power variable-speed power generation system according to claim 1. The control block is a first PI controller that generates a generator output power command value by inputting a difference between the DC voltage command value Vdc ^* and the DC voltage detection value Vdcdet;
The difference between the generator output power command value generated by the first PI controller and the generator output power detection value of the permanent magnet synchronous generator is input to generate the operation amount command value of the flow rate adjusting unit The self-operated apparatus according to claim 1, further comprising a PI controller. The freewheeling system according to any one of claims 1 to 3, wherein a flywheel is connected between the water wheel and the permanent magnet synchronous generator. The flywheel is at maximum power output speed n ₀ or more speed ranges on efficiency characteristic curve of the hydraulic turbine, small hydroelectric variable speed power generation system according to claim 4, characterized by having an inertia to respond to an increase or decrease of the load Stand-alone operation device.

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