Sensitivity Based Voltage Support Strategy to Enhance Dynamic Stability of Islanded Microgrid

Abstract

Every network contains different characteristics. In particular, microgrids have unique features compared to utility grids such as high resistance to reactance ratio(R/X). Consequently, both active and reactive current injection is likely to improve the dynamic voltage stability (DVS) of the islanded microgrids. Therefore, instead of injecting only reactive current, both active and reactive current is injected in the proposed voltage support(VS) strategy. Contrarily, without considering the distinctive characteristics of the network, other strategies with both active and reactive current injection provide fixed and uniform active and reactive current for all networks. To convey the distinctive features of network, voltage sensitivity subject to active and reactive current injection is used in the proposed VS strategy. As a consequence, unlike other strategies, the proposed strategy provides unique combination of active and reactive current for every network. The concept and derivation of the proposed strategy is described. Voltage sensitivity analysis is carried out to determine the sensitivity coefficients. The effectiveness of the proposed strategy is theoretically demonstrated and compared with other strategies. Case studies and result analysis on two islanded microgrids show that the proposed VS strategy for photovoltaic system is capable of enhancing the DVS of islanded microgrids compared to other strategies.