Stability Analysis And Nonlinear Robust Control For Power Systems With STATCOM

The Flexible AC Transmission System (FACTS), which has been developing recently, is a kind of controlling device that is used for improving performance of power transmitting systems. The study is focused on the issues concerning static synchronous compensator (STATCOM), one of the members of FACTS. The dissertation involves the effect of STATCOM on the stability of electric power systems when it operates in power systems, the nonlinear dynamic models of STATCOM and the power systems with it, exact linearization of the models, the decentralized controller for power systems with STATCOM and dynamic experiment of it.On the principle of STATCOM and its structure, the paper analyses its steady model on the basis of which the second order swing equation of one-machine infinite-bus power system with it is obtained. According to the equation, the stability of the system is analyzed with Lyapunov direct method and a kind of Lyapunov function for the system with first integral method. However, the function exists flaw of conservation in estimating the domain of the stability. A more practical Lyapunov function is derived and its sufficient argument is given. Based on the derived Lyapunov function, we analyze the domains of asymptotic stability when STATCOM operates steadily and compares the results with and without those of STATCOM. The simulating results is given. In addition, we study the effect of STATCOM on static voltage stability of one-load infinite-bus power system. For one of the typical loads, inductive motor, we give the load bus' static reactive power - voltage characteristics, basing on which, we analyze and compare the voltage stability surplus of the systems with and without STATCOM.According to the relation of the voltage and current of STATCOM and those of linked power system, we derive a kind of nonlinear transient model from system prospective, which is mapped to d-q-0 coordinate system with Park transformation. Based on the model and the principle of voltage source inverter, we obtain two-layer control structure for STATCOM. At the same time, we give nonlinear dynamic model of the power system with STATCOM. From above, we can see out that power system characters seriously with non-linearity and STATCOM strengthens the characteristics because of the inverter consisting of high-power electronic component. Then we linearize themodels above with accurate linearization method based on coordinate mapping and state feedback and direct feedback linearization.In the models above there exist uncertainty which is due to the remote signals which is hard of transmission and external disturbance hard to ascertain. However, robust control method has provided with efficient manner. So, we introduce description of a class of hybrid uncertain systems, which is comprised of nominal model, types of uncertaity, uncertain boundary and decomposition. Then we study the solution to robust stabilization for hybrid uncertain systems based on the solution to single uncertain issues.Furthermore, we apply the solutions above into power systems with STATCOM and give decentralized control. In the applying for one-machine infinite-bus power system with STATCOM, the linearized model is necessarily dealt with and the robust controller for STATCOM and generator excitation are given. In application to multi-machine system, which is much more complicated than one-machine system, we at first give its transient model, based on which the robust controller for the system is designed. In simulation, we study three models which are one-machine infinite-bus, multi-machine power systems with STATCOM and one-load infinite-bus system. The simulating results of the models are given separately.Finally, we apply the theory into an experiment apparatus. In this part we introduce the hardware structure and design of control software for the apparatus and give the results of dynamic experiment.