Abstract: According to one embodiment, there is provided a variable-speed operation control apparatus of a hydroelectric power generation system including a power generator interconnected to a power system through a main circuit and a water turbine directly connected to the power generator. The apparatus includes a branch circuit branched from the main circuit and including a frequency converter which performs conversion between an output frequency of the power generator and a system frequency of the power system, wherein the power generator is interconnected to the power system through the branch circuit when a flow rate of water is less than a fixed level.

Abstract: According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

Abstract: According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

Abstract: In one embodiment, a control system of a variable speed pumped storage hydropower system includes an optimization processing unit configured to calculate a flow rate adjusting valve opening demand value and a first command value, a speed control unit configured to generate a secondary current active power component command value of a secondary excitation device based on the first command value, a mechanical (pump-turbine) output compensation unit configured to calculate a compensation value of the opening of the flow rate adjusting valve and/or a compensation value of the generator-motor output, and an output control unit configured to generate a flow rate adjusting valve opening command value based on the generator-motor output command value, the flow rate adjusting valve opening demand value, the compensation value calculated by the mechanical output compensation unit, and the output detection value of the generator-motor.

Abstract: According to one embodiment, there is provided a variable-speed operation control apparatus of a hydroelectric power generation system including a power generator interconnected to a power system through a main circuit and a water turbine directly connected to the power generator. The apparatus includes a branch circuit branched from the main circuit and including a frequency converter which performs conversion between an output frequency of the power generator and a system frequency of the power system, wherein the power generator is interconnected to the power system through the branch circuit when a flow rate of water is less than a fixed level.

Abstract: In one embodiment, a control system of a variable speed pumped storage hydropower system includes an optimization processing unit configured to calculate a flow rate adjusting valve opening demand value and a first command value, a speed control unit configured to generate a secondary current active power component command value of a secondary excitation device based on the first command value, a mechanical (pump-turbine) output compensation unit configured to calculate a compensation value of the opening of the flow rate adjusting valve and/or a compensation value of the generator-motor output, and an output control unit configured to generate a flow rate adjusting valve opening command value based on the generator-motor output command value, the flow rate adjusting valve opening demand value, the compensation value calculated by the mechanical output compensation unit, and the output detection value of the generator-motor.

Abstract: There is provided a current tracking PWM control circuit that directly generates PWM signals such that inverter output currents id, iq track PWM current references id**, iq**, using the results of comparison of the inverter output currents id, iq and PWM current references id**, iq**, in which, if current references id*, iq* exist, the result of adding the original current reference iq* and a correction signal iqC*, obtained by amplifying the deviation (iq*-iq) of the current reference iq* and iq, is used as the PWM current reference iq** on the q axis side for performing current control, but, in respect of the d axis side, the original current reference id* is used directly as the PWM current reference id** for performing current control.

Abstract: There is provided a current tracking PWM control circuit that directly generates PWM signals such that inverter output currents id, iq track PWM current references id**, iq**, using the results of comparison of the inverter output currents id, iq and PWM current references id**, iq**, in which, if current references id*, iq* exist, the result of adding the original current reference iq* and a correction signal iqC*, obtained by amplifying the deviation (iq*-iq) of the current reference iq* and iq, is used as the PWM current reference iq** on the q axis side for performing current control, but, in respect of the d axis side, the original current reference id* is used directly as the PWM current reference id** for performing current control.