Study On Transient Stability Preventive Control Based On Trajectory Sensitivity And Quadratic Programming

The preventive control for power system transient stability is one of the key techniques to enhance the security and stability of the whole system. So far, there are two main methods for transient stability preventive control. One is the multi-level control method based on trajectory sensitivity, and the other is the transient stability constrained optimal power flow method. The former gains the preventive control strategy by tentative adjustment and repetitive rectification, which is inefficient and cannot lower the control cost; the later adds transient constrains into optimal power flow and then solve the large-scale nonlinear programming problem to get the control strategy, which is very complicated and easy to get into misconvergence. Combining the advantages of both methods, this thesis builds a quadratic programming model based on trajectory sensitivity and then use it to make the fast and economical transient stability preventive control strategy.Firstly, this thesis analyzes and compares the two existing methods for transient stability preventive control:the multi-level control method based on trajectory sensitivity and the transient stability constrained optimal power flow method; the weaknesses and strengths are listed and compared.Secondly, this thesis builds the quadratic programming model based on trajectory sensitivity. The objective function is the control cost function; the constrains contains active power balance contrains, active power limits constrains and transient stability constrains; the optimizing variables are active power of relative adjustable generators. Using the partial linearization function of the trajectory sensitivity, this thesis transfers the transient stability constrains into linear constrains and then uses the active set method to solve this model.Then, this thesis proposes a new transient stability preventive control method based on trajectory sensitivity and quadratic programming. By generator group division and relative adjustable generator selection, the new method limits the number of adjusting generators. The trajectory sensitivity is solved by general minimum residual method (GMRES).The method is rectified by the transient stability time domain simulation method to meet the requirements of power system transient stability.Finally, the new method is verified by simulations on the New England39bus system and the power grid of NorthEast China. The results of the simulations using both the auxiliary decision making function of PDSA and the new method are analyzed and compared to confirm the rapidness and economy of the new method.