| 摘要 |
PURPOSE:To obtain a method for detecting the single operating state surely even if a plurality of inverters are interconnected after interruption of a system. CONSTITUTION:A reactive power variation command having a constant period is delivered from an oscillator 13 in order to operate an inverter 3 and to monitor a system voltage Vs. When a comparator 17A detects a variation in the output frequency of an inverter exceeding a predetermined level, a switch 14 is closed to add a frequency variation component to the reactive power variation command thus detecting a single operating condition surely by means of a comparator 17B. |
