SYSTEM INTERCONNECTION INVERTER

摘要

PROBLEM TO BE SOLVED: To stop operation completely if a system interconnection inverter is disconnected from a system, by stopping operation if the frequency of a zero cross signal which a zero volt phase position(ZVP) preparing means prepares exceeds its allowable value. SOLUTION: If a system 3 has power failure, or opening of a switch or the like occurs, the voltage and frequency on both sides of a load 31 fluctuates, and a voltage detection means 18 grasps a change in output voltage and frequency under the fluctuating condition. A zero volt phase position(ZVP) preparing means 19 prepares a ZVP signal under the condition and transmits it to a control means 30. A control means 30 stops an inverter means 16 if the frequency detected based on a ZVP signal which the ZVP preparing means 19 prepares exceeds its allowable value. It is thus possible to stop operation completely if the load 31 is disconnected from the system 3 by power failure or the like.