Islander operation detection device for distributed power supply

摘要

PROBLEM TO BE SOLVED: To provide an isolated operation detection device capable of making secure detection of an isolated operation compatible with prevention of erroneous detection in the case where system disturbance occurs.SOLUTION: An isolated operation detection device 10a comprises a control device 30a and an isolated operation monitoring device 32. The control device is functioned to control an inverter 6 and then output a three-phase fundamental wave current in the same frequency as a fundamental wave of a power distribution system 2 while superposing an inter-dimension harmonic current Vof a non-integer-multiple dimension (m) of the fundamental wave thereon in a single-phase manner. The isolated operation monitoring device measures an inter-dimension harmonic voltage Vof the non-integer-multiple dimension (m) at a measuring point 24 on a cooperation line 22 and detects that a distributed power source 8 turns to isolated operation, from a change of the voltage V. The control device 30a includes an inter-dimension harmonic current correction circuit 72 which calculates a rate of change for a magnitude of the inter-dimension harmonic current Iflowing through the measuring point 24 from a value predetermined time before and increases the inter-dimension harmonic current Ioutputted from the inverter 6 in inverse proportion to the calculated rate of change.SELECTED DRAWING: Figure 3