Security region based security-constrained unit commitment

Abstract

As the issues of security and stability of power systems are becoming increasingly significant, it is necessary to consider the constraints of the static voltage stability and transient stability, which are closely related to the active power dispatch of power systems, in the daily power dispatch, i.e. the unit commitment. However, due to the complexity of these constraints and limitation of the existing analysis methods, there has been no unit commitment model reported so far that can deal with these security constraints. On the other hand, as lack of effective measures to evaluate the security margin of dispatch schemes, it is difficult for power system operators to integrate both the security and economy of power systems in unit commitment. To resolve the above-mentioned issues, a security region based security-constrained unit commitment model is presented in the paper, which gives consideration to both the security and economy of power systems. For the first time, the active power flow constraint, the static voltage stability constraint and the transient stability constraint are taken into account in unit commitment at the same time. The model presented in the paper takes the operating cost, the branch transmission capacity margin, the static voltage stability margin and the transient stability margin as sub-objectives. By adjusting the weighting factors of sub-objectives, it is convenient to adjust the preference on the security and economy of power systems and reach a balance. The IEEE RTS-24 test system is adopted to validate the correctness and the efficiency of the proposed model.