Reactive Power Optimization And Voltage And Reactive Power Support Mechanism

Reactive power optimization is an important part in the power system operation and dispatch. So it has great significance to develop reactive power optimization method, reactive power and voltage operation mechanism and the special problems in the engineering application.The primal-dual interior point algorithm has been proved splendid effective compared with other reactive power optimization methods, but it is still difficult to solve the KKT conditions, especially in large power system. In this thesis, a nonlinear primal-dual interior point algorithm is used to solve a reactive power optimization model with the least variables under a certain active power dispatching mode, and a solution structure which is composed of the state variable of power system is presented to solve the KKT conditions. The effects of inequalities are transferred to equalities with this structure and a reduced correction equation is obtained which contains the bus voltages and Lagrangian multipliers. The computation results of test systems verify that the algorithm is adapt to large power systems and real-time requirement.The mathematical and physical rules of reactive power optimization have not been fully explained because of the variety of control measures, the local characteristics of reactive power and the nonlinearity of this problem. And then in this thesis, with the above model, three solution states which reflect the restriction degree between the distribution of reactive power and the voltage level are put forward according to the different effects of the bus voltage constraints in the optimization results. Some optimization results of a simple 3-bus system with two power sources and the IEEE 30-bus system are shown as examples to reveal that this model will play an important rule in voltage and reactive power regulating and controlling.As the byproduct of the reactive optimization above, Lagrangian multipliers and slack variables which are respond to functional inequalities and reactive power flow equations of the power system, because of their characters and numerical variation laws, can reflect the supporting rule of voltage and reactive power in the power system. According to these characteristics, an efficient network partition method was proposed. With this method, one can determine which node need critical control and which node have enough reactive power reserve. This is a self-adaptive method and it can regulate itself when the system operation changes. This character is helpful when secondary voltage controllers are designed and implemented.