Preventive Security-Constrained Optimal Power Flow With Constraints Limiting The Number Of Control Actions

Security-constrained optimal power flow(SCOPF) is one of the most important means to balance security and economy. In recent years, large-scale blackout occurred in some power systems of Euramerican developed countries due to the lack of steady-security margin. Nowadays, SCOPF is attracting more and more attentions of scholars.In this paper, a preventive security-constrained optimal power flow with constraints limiting the number of control actions model(PSCOPF-LC) is proposed to deal with the problem of shifting operation point from a current operation point to a PSCOPF satisfied operation point often need to use all control actions. Proposed model limit the number of control actions, which is defined as constraints limiting the number of control actions, in the process of shifting operation point, hoping to change current operation point to steady-security satisfied operation point. In view of proposed model belong to MINLP problem, the original model, in this paper, is converted into MPEC problem. Finally, applying the relaxation technique, MPEC is transformed into a NLP problem and solved by PDIPM successfully.In order to reduce the size of the SCOPF problem, a steady-security support system is built in this paper, which contains network topology analysis module, steady-security assessment module, classical PSCOPF module, outage sorting and filtering module and PSCOPF-LC module. In the steady-security assessment module, a compensation method base on fixed node voltage is proposed to improve speed and accuracy of N-1outage.The numerical results of IEEE-14, IEEE-30and IEEE-118standard system show that the proposed model can reduce the number of control actions effectively during the process of shifting operation point and lower the cost. For improving the reliability of power system, the proposed model has important practical significance. The computational accuracy of proposed compensation method base on fixed node voltage performs better when compared with conventional compensation method, and ensures the voltages of PV buses are constant during the compensational process.