Contingency Simulation Using Single Phase Quadratized Power Flow

Contingency simulation is an essential but computationally demanding procedure for power system security assessment, reliability evaluation, and real time operation. Simulation methods based on the traditional power flow (TPF) model usually suffer from lack of the realistic system model and slow convergence. To solve such problems, this paper proposes a contingency simulation methodology based on a single phase quadratized power flow (SPQPF) model that integrates the compensation method and sparsity techniques. Two major advantages of the SPQPF model exist in its ability to model realistic system component characteristics and its superior performance in achieving faster convergence, which are important to simulate contingencies realistically and efficiently. In the proposed framework, a hybrid contingency selection technique is applied first to categorize system contingencies into two classes: (1) contingencies that cause system linear changes and (2) contingencies that cause system nonlinear changes or discontinuities. The first class constitutes the majority of contingencies while the second class includes only a small portion of contingencies. For contingencies in class 1, the very first iteration of SPQPF can provide satisfactory solutions due to its faster convergence feature, compared to the several iterations generally required by TPF. To further reduce the computational effort, a sparse oriented compensation method that performs the first iteration is developed based on the SPQPF model. For the second class of contingencies, a quasi compensation iterative method is developed to analyze contingencies with high efficiency and acceptable accuracy. The proposed methodology is able to simulate the post contingency situation efficiently in a realistic manner and provide a good balance between efficiency and accuracy in the procedure of contingency simulation. Its performance is demonstrated with IEEE reliability test systems