Analytical Model of Inverter-Interfaced Renewable Energy Sources for Power System Protection

The accurate analytical fault analysis model of the emerging inverter-interfaced renewable energy sources (IIRESs) is an important basis for protection of power system with RESs. However, factors of dynamic characteristics of the control system (DCCS) such as the controller saturation and phase-locked loop (PLL) dynamics have rarely been simultaneously studied in the existing analytical models of IIRESs. As a result, the accurate analytical models can hardly be guaranteed. To address this issue, this paper proposes an analytical model for IIRESs taking DCCS into account to characterize the complex fault responses of IIRESs. Both the controller saturation and PLL dynamics are considered in the transient and steady-state phases to investigate the fault current characteristics. On this basis, the analytical fault current formulations under the influences of DCCS are yielded using the piecewise linearization method. Field short-circuit and simulation tests indicate that the proposed model is applicable to various fault conditions and its calculation accuracy can be improved by at most 55% in comparison with the existing IIRESs’ analytical models.