Abstract: A device for suppressing voltage fluctuation and higher harmonics of a power source system which supplies power to a load with large power fluctuation and large harmonic current. The device includes a self-commutated converter arranged in parallel with the load and a control circuit for controlling the self-commutated converter. The control circuit includes a compensation current variable calculation circuit for calculating a plurality of compensation current variables based on electrical quantities of the power source system and the load, a compensation gain calculation circuit for determining at least one compensation gain based on at least one of the compensation current variable, and a current instruction value calculation circuit for calculating a plurality of respective current instruction values based on the compensation gain and a plurality of the respective current compensation variables.

Abstract: Higher harmonic power components and fundamental wave reactive power components are derived from a load voltage and current, using theory (instantaneous p-q theory) regarding instantaneous real power and instantaneous imaginary power. Gains are then obtained which make the higher harmonic power components and fundamental wave reactive power components not exceed predetermined limit values. The higher harmonic power components and fundamental wave reactive power components are respectively multiplied by the gains to obtain limited higher harmonic power components and fundamental wave reactive power components. An output current command is generated in accordance with the limited higher harmonic power components and fundamental wave reactive power components. The output current command is supplied to an inverter which in turn supplies a compensation current to the power system.

Abstract: A device for suppressing voltage fluctuation and higher harmonics of a power system which supplies power to a load with large power fluctuation and higher harmonic current. The device includes a self-commutated converter and a higher harmonic filter, both provided in parallel with the load. The device includes a first calculation circuit which calculates a reactive power consumed by the load based on a load current and system voltage and generates a fundamental harmonic current command value to compensate the reactive power. The device further includes a second calculation circuit which detects a higher harmonic current flowing out to the power system based on a current flowing from the power system and generates a higher harmonic current command value to suppress the higher harmonic current. The device further includes an adder which adds the fundamental harmonic current command value and the higher harmonic current command value to generate a current command value of the self-commutated converter.