Analysis of transient-to-island mode of power electronic interface with conventional dq-current controller and proposed droop-based controller

Distributed generation (DG) is predicted to play an increasingly important role in the future power system. DGs, however, can provoke technical problems when they are added to the existing system. An islanding is one of those problems while using DGs. During that mode, the power electronic interface of DGs has both roles of keeping the point of common coupling’s voltage within a required range and making islanded frequency arbitrarily at normal values. This paper investigates the operation response while keeping the conventional current controller in some cases of typical islanded loads. Then, it validates the feasibility of a proposed droop-based current controller for the islanded entity dealing with transient-to-island mode using PSCAD simulation. That proposed controller is fast switched from the conventional one using the negative-sequence impedance islanding detection method. The stability analyses of an islanded entity and islanded controller regarding frequency, voltage and transient period are also carried out in depth.