Patent ID: 8039991
Filing Date: 2011-10-18
Classification: H02J

Abstract:
1. A cogeneration system having a first power plant connected to an AC power feed line between a power network and an electrical load and a first internal combustion engine for driving the first power plant such that exhaust heat of the first engine is supplied to a thermal load, comprising: a second power plant connected to the feed line at a connection in parallel with the first power plant, the second power plant including a second internal combustion engine for driving the second power plant; a switch installed in the feed line at a location upstream of the connection; a power network outage detector that detects outage of the power network; a power supply interrupter that interrupts power supply from the first power plant to the power network by turning off the switch, when the outage of the power network is detected; a first generator included in the first power plant and driven by the first engine; a second generator included in the second power plant and driven by the second internal combustion engine; a first inverter connected to the first generator to invert output of the first generator to AC power; a second inverter connected to the second generator to invert output of the second generator to AC power; a phase detector that detects phase of output of the second inverter; and a power plant operator that operates the second power plant, such that outputs of the first and second power plants are supplied to the electrical load when the power supply from the first power plant to the power network is interrupted and operates the first inverter to output the AC power in same phase as the detected phase of the output of the second inverter, such that inverted AC power of the first and second generators in the same phase are supplied to the electrical load.