COMPENSATING DEVICE FOR INSTANTANEOUS VOLTAGE DROP

摘要

PURPOSE:To accurately compensate an instantaneous drop of the voltage applied to a load by controlling the compensating voltage outputted from a compensating power supply so as to decrease the difference between the reference sine wave voltage having an amplitude and a phase corresponding to the normal voltage of an electric power system and said load voltage. CONSTITUTION:A compensating power supply 6 containing an energy storing means 10 is put in series into a power supply path to a load from an electric power system 1. A bypass switch element 3 is connected between both ends of the power supply 6. A switching control circuit 34 controls the compensating voltage VH outputted from the power supply 6 so that the difference is decreased between the reference sine wave voltage V32 having an amplitude and a phase equivalent to the normal voltage of the system 1 and the load voltage VL applied to the load 2. At the same time, a bypass switch control circuit 36 switches the element 3 to an OFF state from an ON state when the system 1 has an instantaneous voltage drop. In such a way, the instantaneous voltage drop can be compensated.