Research On Security-Constrained Optimal Power Flow Including Conflicting Contingencies

The Security-constrained optimal power flow (SCOPF) is an important research topic to ensure the safe operation of the power system and handling a variety of expected contingencies. With the increasing penetration of renewable generation in modern power systems, uncertainty has become one of the biggest challenges in power system operation. Due to massive integration of variable generation, system operators have been enduring more and more unplanned disturbances and outages. Thus, when arranging the operating schemes, the goal of the SCOPF problems is to find the most economical operating point on condition that it satisfies as many expected contingency scenarios as possible. The dimension of SCOPF problems sharply increases as system scale and security requirements increase due to the large contingency sets under consideration. This can result in excessive dimensionality, which can exhaust computational memory and lead to unacceptable processing times. Meanwhile, some conflicting contingencies may exist, i.e. a series of contingencies that cannot coexist in the corrective contingency set of a CSCOPF problem. Therefore, this paper mainly focuses on the research of PSCOPF and CSCOPF problems including conflicting contingencies. The main research contents are listed as followed:Firstly, we propose a contingency filtering approach for solving PSCOPF problems including conflicting contingencies. The modified PSCOPF model is demonstrated to deal with conflicting contingencies. The method takes the degree of inequality constraints violations in post-contingency states as the filter indices to form the set of key contingencies. And then the PSCOPF considering the key contingencies is calculated. On the other hand, the norm of equality constraints Lagrange multiplier indicates the sensitivity of expected contingencies to the objective function, which determines the severity of each conflicting contingencies, removing the most sensitive contingency. Thus the contingency filtering strategy can find the most economical operating point on condition that it satisfies as many expected contingency scenarios as possible.Then, a contingency filtering approach for CSCOPF including conflicting contingencies is demonstrated. For conflicting contingencies, a modified CSCOPF model, which is applicable for the problems whether there exists conflicting contingencies, is proposed. Based on the modified CSCOPF model, the rescheduling indices in post-contingencies states are selected for contingency filtering. On the other hand, the novel iterative contingency filtering strategy is utilized to handle conflicting contingencies, which depends on the degree of influence on the objective function. Meanwhile, the original dual system in the predictor-corrector interior point method is decomposed into several blocks matrices to form the block bordered diagonal (BBD) matrix, and the decomposed parallel interior point method is utilized to improve the efficiency of solving the CSCOPF problems considering the key contingencies.This proposed PSCOPF and CSCOPF contingencies filtering approaches are successfully applied on the IEEE standard systems and the real world power systems. The results prove that these approaches can deal with conflicting contingencies effectively and improve the calculation efficiency. Meanwhile, it provides new ideas to deal with the power system conflicting contingencies, which has the benefit of keeping the safe operation of the power system better.