Power conversion system and power conversion control method

A power conversion system interconnected to a multi-phase AC power system, the power conversion system comprising:

• first and second converters provided in parallel for each phase of the power system;
• and
• a control unit configured to control the first and second converters according to carrier comparison type PWM control using a plurality of carrier signals including first and second carrier signals having a prescribed phase difference from each other,
• wherein the control unit detects a current of a primary side of the first and second converters at four or more even-numbered timings when the four or more even-numbered timings are defined at prescribed time intervals during one cycle of the first carrier signal,
• wherein the control unit generates a reference voltage for the PWM control using a value of the detected current of the primary side and a value of a reference current of the primary side and updates the reference voltage at each of the four or more even-numbered timings, and
• wherein the control unit controls the first converter using the first carrier signal and the updated reference voltage and controls the second converter using the second carrier signal and the updated reference voltage.

A power conversion control method for use in a power conversion system interconnected to a multi-phase AC power system, the power conversion control method causing a computer to:

• in a carrier comparison type PWM control process of controlling a plurality of switches included in a plurality of converters provided in parallel for each phase of the power system using a plurality of carrier signals having a prescribed phase difference from each other,
• detect a current of a primary side of the plurality of converters at each of four or more even-numbered timings when the four or more even-numbered timings are defined at prescribed time intervals during one cycle of a specific carrier signal among the plurality of carrier signals,
• generate a reference voltage for the PWM control using a value of the detected current of the primary side and a value of a reference current of the primary side and update the reference voltage at each of the four or more even-numbered timings, and
• control a specific converter among the plurality of converters using the specific carrier signal and the updated reference voltage.