Credibility theory to handle uncertain renewable energy: A fuzzy chance constrained AC optimal power flow

This paper focuses on distribution system featuring renewable energy sources (RESs), and proposes a credibility theory-based fuzzy chance-constrained AC optimal power flow (FCC-ACOPF) model to hedge the uncertainty of RESs generation. Credibility constraints in the proposed model are utilized to enforce voltage and controllable generator power regulation with a predefined credibility, so that distribution system operator can select an acceptable credibility to reduce the risk of voltage violation. Besides, the optimal scheme obtained by the FCC-ACOPF model meets the predefined credibility without the symmetry assumption of RESs forecast error, which avoids making an ineffective and inefficient operating decision that may be caused by RESs forecast strongly skewed. Finally, the linear explicit expressions of controllable generator and node voltage in FCC-ACOPF are derived to make the proposed model be handled by off-the-shelf solvers. Comprehensive studies based on a modified 15-node system are conducted to demonstrate the rationality and effectiveness of the proposed method.