Improved Island Microgrid Fault Analysis by Considering the Effect of DG Control Methods

During system faulty condition, the output of inverter-type distributed generation is different from the traditional generation but according to the different distributed generation (DG) control methods. In this paper, a new fault analyzing method which considers the negative effect of DG control methods is proposed. Firstly, an equivalent fault analysis model of inverter type DG is developed by considering the constraints of different control methods, in terms of active and reactive power (PQ) control and V/F control. Based on the equivalent model, the fault analysis of island microgrid under the scenarios of PQ and V/F control is carried out by establishing equivalent island microgrid model. The fault voltage and current are calculated by solving the constrain equations based on different DG controls. Besides, both symmetrical and asymmetrical fault conditions are analyzed. Finally, the well-developed power grid simulation software DIgSILENT is applied to build a typical micro-grid model containing inverter-type DGs which is functioned with PQ control and V/F control. The results of the proposed analysis method are compared with the well-developed simulation results and typical conventional analyzing method. The comparison results verify that the proposed fault analysis method is effective and has great accuracy on the computation of fault data.