Tentative Study On Power System Coordination Control

Modern power systems are featured with extra high voltage level, long-distance transmission lines, large capacity generators, spaciously inter-connections and huge inter-area exchanges. Any instability accidents can cause enormous losses and catastrophic results. So studies on the power system security and stability have been paid much more attention nowadays. At the same time, wide application of Flexible AC Transmission System (FACTS) can bring many benefits to power systems, e.g. they can effectively increase the line transfer capability and enhance the system stability. However, with more and more FACTS devices being installed to power systems, coordination control among them should be paid much more attention. The phasor measurement unit and wide-area measurement system (PMU/WAMS) have been widely used in modern power systems, which can provide the necessary remote information for the coordination controls. In this thesis, power system coordination control is tentatively studied. The thesis can be divided into following two parts:Part 1: a method to improve power system small signal stability through optimizing the generator dispatch is discussed. Firstly, an optimal-based boundary tracing algorithm for the small signal stability region is introduced. And, WSCC 3-machine-9-bus system is employed to do some verification studies. Impact of load level and generation dispatch on small signal stability region is studied. It is found that the load level has significant influence to the composition of the small signal stability region and its topological characteristics. However, generation dispatch only affects the current operating point and has no influence to the small signal stability region. Based on the result, we can coordinate the generator outputs to enhance power system stability.Part 2: a tentative study on coordination control based on the projective control technique is performed. Firstly, necessary background to the projective control is briefly reviewed. Then a method to coordinate power system stabilizers is given, which is applied to WSCC 3-machine-9-bus system to optimize the parameters of two power system stabilizers. Simulation result shows the effectiveness of the proposed method.Power system coordination control is a wide study field. In this thesis, only a preliminary theoretical study is performed. A lot of work should be done before the proposed method is put into practice.