A Robust Three-Phase Power Flow for Active Distribution Network Embedded Autonomous Voltage Regulating Strategies

Large-scale distributed generators (DGs) penetrated into the active distribution network (ADN) impact the voltage profile significantly. Autonomous voltage control strateges simulation becomes an crucial issue in the ADN steady state analysis. Conventional Newton-Raphson or fixed point iteration based power flow convergence failure is frequently incurred by heuristic Q-limit adjustment of DGs and voltage band regulation of step voltage regulator (SVR). To cope with these issues, mixed complementarity problem (MCP) is formulated to model the Q-limit issue of voltage controlled DGs and voltage regulation of SVR etc.. To improve the convergence of the proposed method, nonlinear equations are linearized with Newton algorithm and then fast Lemke algorithm are utilized to solve the linear complementarity programming model (LCP). The effectiveness and better performance of the proposed method under operation off-limit of DGs and tap adjustment of SVRs were validated using unbalanced IEEE 4, 34, 123 test feeder and other large practical three-phase network test case.