A thermal power generation apparatus (1, 101, 201, 301, 401, 501, 601) comprising: a heat engine (20, 30, 40, 50); a power generator that generates alternating-current power from the extracted mechanical power; a converter that generates direct-current power (P b, P dc) from the generated alternating-current power; an inverter that is connected to the converter via a direct-current power line, the inverter being suitable for generating alternating-current power from the direct-current power (P b, P dc) and outputting the alternating-current power to a commercial system; an electric power absorber (6, 6a, 6b, 6c) that is connected to the direct-current power line connecting the converter and the inverter, the electric power absorber (6, 6a, 6b, 6c) being suitable for absorbing at least part of the direct-current power (P b, P dc) transmitted from the converter toward the inverter; and a control circuit (7, 70, 71, 72) that, during operation of the apparatus, detects a voltage drop and voltage recovery in the commercial system and selects a single operation mode from among a plurality of modes including a normal mode and a specific mode; characterized in that the heat engine (20, 30, 40, 50) is suitable for extracting mechanical power from heat supplied by a heat supply source, the mechanical power being a rotary action; wherein the control circuit (7, 70, 71, 72), when selecting the normal mode, controls the inverter to adjust the alternating-current power output (P o) from the inverter, thereby causing a direct-current voltage (V dc) in the direct-current power (P b, P dc) line to follow a target voltage, and wherein the control circuit (7, 70, 71, 72), when selecting the specific mode, controls the inverter to adjust the alternating-current power output (P o) from the inverter, thereby causing the direct-current voltage (V dc) in the direct-current power line to follow the target voltage and controlling the electric power absorber (6, 6a, 6b, 6c) to absorb at least part of the direct-current power (P b, P dc), the amount of the alternating-current power output (P o) from the inverter in the specific mode being larger than zero and smaller than that in the normal mode. a heat engine (20, 30, 40, 50); a power generator that generates alternating-current power from the extracted mechanical power; a converter that generates direct-current power (P b, P dc) from the generated alternating-current power; an inverter that is connected to the converter via a direct-current power line, the inverter being suitable for generating alternating-current power from the direct-current power (P b, P dc) and outputting the alternating-current power to a commercial system; an electric power absorber (6, 6a, 6b, 6c) that is connected to the direct-current power line connecting the converter and the inverter, the electric power absorber (6, 6a, 6b, 6c) being suitable for absorbing at least part of the direct-current power (P b, P dc) transmitted from the converter toward the inverter; and a control circuit (7, 70, 71, 72) that, during operation of the apparatus, detects a voltage drop and voltage recovery in the commercial system and selects a single operation mode from among a plurality of modes including a normal mode and a specific mode; characterized in that the heat engine (20, 30, 40, 50) is suitable for extracting mechanical power from heat supplied by a heat supply source, the mechanical power being a rotary action; wherein the control circuit (7, 70, 71, 72), when selecting the normal mode, controls the inverter to adjust the alternating-current power output (P o) from the inverter, thereby causing a direct-current voltage (V dc) in the direct-current power (P b, P dc) line to follow a target voltage, and wherein the control circuit (7, 70, 71, 72), when selecting the specific mode, controls the inverter to adjust the alternating-current power output (P o) from the inverter, thereby causing the direct-current voltage (V dc) in the direct-current power line to follow the target voltage and controlling the electric power absorber (6, 6a, 6b, 6c) to absorb at least part of the direct-current power (P b, P dc), the amount of the alternating-current power output (P o) from the inverter in the specific mode being larger than zero and smaller than that in the normal mode.