Multi-Stage Voltage Support Optimization for Microgrids with Multiple Distributed Generation Units

With the proliferation of microgrids (MGs) into the utility grid (UG), MGs with multiple distributed generations (DGs) face challenge to flexibly support voltage during UG faults. In this paper, a multi-stage voltage support optimization method is proposed to stabilize voltage, current and power, for safeguarding the MG operation and providing flexible power delivery capacity. The proposed method consists of three stages: 1) voltage stage in which the phase voltage instead of the sequence voltage regulation is considered to support voltage more precise; 2) current stage in which a novel current generation strategy with maximum current limiting (MCL) is formulated by directly embedding network impedance features; 3) power stage in which multiple matching scenarios for max/min active/reactive powers are developed to improve the flexibility of power delivery capacity. Several test cases are presented and pertinent results are discussed to validate the effectiveness of the proposed method for voltage support of MG with multiple DGs.