System interconnection electric power generator and control method therefor

A system interconnection electric power generator having various kinds of equipment for generating electric power and supplying the electric power to a commercial power supply system electrically-connected thereto, comprising

• an electric power generator for generating DC power;
• a boosting circuit for boosting the DC power generated in said electric power generator;
• an inverter circuit for converting the DC power boosted in said boosting circuit to AC power;
• a controller for controlling at least said boosting circuit and said inverter circuit;
• plural DC lines connected between said electric power generator and said boosting circuit so that direct current achieved in said electric power generator flows through said plural DC lines;
• and a DC earth fault detector for measuring the difference in current between said plural DC lines extending from said electric power generator to detect whether DC earth fault occurs or not in said system interconnection electric power generator, wherein said DC earth fault detector comprises a current sensor disposed on said plural DC lines, and said current sensor has a detecting core formed of a zero current transformer (ZCT).

A system interconnection electric power generator having an electric power generator (11) for generating DC power, a boosting circuit (14) for boosting the DC power supplied from the electric power generator (11) to a predetermined voltage larger than the system voltage of a commercial power line, said boosting circuit (14) being equipped with a capacitor (26) for charging DC power, an inverter circuit (15) for converting the boosted DC power to AC power and supplying the AC power thus converted through said commercial power line to a commercial power supply system (13), and a microcomputer (17) for controlling the boosting circuit (14) and the inverter circuit (15), characterized by further comprising:

• a switched power source that is connected between said boosting circuit (14) and said microcomputer (17) and directly supplied with the DC power charged in said capacitor (26) from said boosting circuit (14) so as to supply regulated DC power to said microcomputer (17) irrespective of variation of the DC power generated by said electric power generator (11), wherein said inverter circuit has at least four arms each having a switching element and a fly-wheel diode, and said capacitor (26) charges the DC power generated by said electric power generator (11) and then boosted by said boosting circuit (14) or DC power achieved by passing AC power from the commercial power line through said flywheel diodes (30) of said inverter circuit (15) to rectify the AC power.