A power conversion apparatus to be applied to a generation system that interconnects with an alternating current power system, the power conversion apparatus comprises: an inverter circuit including a switching element that is adapted to convert a direct current power into an alternating current power; a system voltage measurement means that is adapted to measure a system voltage of the alternating current power system; a carrier wave generation means that is adapted to generate a carrier wave; a carrier wave frequency modulation means; a signal wave generation means that is adapted to generate a signal wave to control the alternating current power output from the inverter circuit; a gate signal generation means that is adapted to compare the carrier wave generated by the carrier wave generation means with the signal wave generated by the signal wave generation means, and is further adapted to generate a gate signal to drive the switching element; and a power conversion control means that is adapted to perform power conversion control of the inverter circuit by pulse width modulation, based on the gate signal generated by the gate signal generation means, characterized in that the power conversion apparatus further comprises: a voltage drop detection means that is adapted to detect a voltage drop (ΔV) of the alternating current power system, based on the system voltage measured by the system voltage measurement means; wherein the carrier wave frequency modulation means is adapted to increase a frequency (fr) of the carrier wave generated by the carrier wave generation means, when the voltage drop (ΔV) is detected by the voltage drop detection means, so that a ripple of a current output from the inverter circuit does not exceed a setting value of an overcurrent relay provided at an output side of the inverter circuit. an inverter circuit including a switching element that is adapted to convert a direct current power into an alternating current power; a system voltage measurement means that is adapted to measure a system voltage of the alternating current power system; a carrier wave generation means that is adapted to generate a carrier wave; a carrier wave frequency modulation means; a signal wave generation means that is adapted to generate a signal wave to control the alternating current power output from the inverter circuit; a gate signal generation means that is adapted to compare the carrier wave generated by the carrier wave generation means with the signal wave generated by the signal wave generation means, and is further adapted to generate a gate signal to drive the switching element; and a power conversion control means that is adapted to perform power conversion control of the inverter circuit by pulse width modulation, based on the gate signal generated by the gate signal generation means, characterized in that the power conversion apparatus further comprises: a voltage drop detection means that is adapted to detect a voltage drop (ΔV) of the alternating current power system, based on the system voltage measured by the system voltage measurement means; wherein the carrier wave frequency modulation means is adapted to increase a frequency (fr) of the carrier wave generated by the carrier wave generation means, when the voltage drop (ΔV) is detected by the voltage drop detection means, so that a ripple of a current output from the inverter circuit does not exceed a setting value of an overcurrent relay provided at an output side of the inverter circuit. a voltage drop detection means that is adapted to detect a voltage drop (ΔV) of the alternating current power system, based on the system voltage measured by the system voltage measurement means; wherein the carrier wave frequency modulation means is adapted to increase a frequency (fr) of the carrier wave generated by the carrier wave generation means, when the voltage drop (ΔV) is detected by the voltage drop detection means, so that a ripple of a current output from the inverter circuit does not exceed a setting value of an overcurrent relay provided at an output side of the inverter circuit.