Patent ID: 6545885
Filing Date: 2003-04-08
Classification: H02J,Y02E

Abstract:
An isolated operation prevention device for a distributed power supply connected to a power system, which injects an intermediate-order harmonic current with a frequency being a non-integer multiple of a system fundamental from a injection point into an incoming line of a customer equipment having said distributed power supply, and detects an interruption of said system on the basis of a voltage at said injection point of said intermediate-order harmonic current and an injection amount of said intermediate-order harmonic current at a receiving point, to cause said distributed power supply to be disconnected from said system, the device comprising:a power fluctuation monitoring unit which monitors and detects a power fluctuation due to a flicker fluctuation at said receiving point on the basis of the voltage at said injection point and the current in said incoming line; a power compensation unit which forms a compensation power injection signal for canceling out said power fluctuation based on the detected power fluctuation; and an inverter device which is driven and controlled by a signal obtained by adding said compensation power injection signal to an injection signal of said intermediate-order harmonic current and injects said intermediate-order harmonic current and a compensation power into said injection point.