| 摘要 |
PROBLEM TO BE SOLVED: To detect a fault condition of an inverter system under the parallel operation by detecting a voltage of an output bus and an output voltage and cross current of an inverter system. SOLUTION: If an inverter system 1a fails, frequency Fa of an output voltage Va becomes smaller than frequency setting value. Current detectors 3a, 3b detect an output current of the inverter systems 1a, 1b and gives it to a difference current detector 30. The difference current detector 30 outputs difference currents Iba, Ibb of cross current of the inverter systems 1a, 1b. A reactive power calculator 8a inputs a difference current Iba and an output Va of a voltage detector 4a and outputs a reactive power Qa. The voltage detector 6 detects an output bus voltage Vv and a frequency detector detects frequency Fv of the output bus voltage. A discriminator 9a inputs the reactive power Qa and output bus frequency Fv and judges the operating condition of the inverter system 1a. |
