Design Of Nonlinear Control For Power Systems With State And Input Constraints

Power systems are extremely complex nonlinear dynamic systems. They include transmission lines and lots of equipments. Because there are lots of contacts and influences between them, the dimensions of power systems are large. With the rapid development of power industry, the power systems have the rapid increase in the size and complexity. It is the inevitable trend for the development of the power systems to provide power safely, economically and reliably. Therefore, the controllers on steam valve and generator excitation for the generator are important to power system. In the paper, considering the above control problems, it designs the coordinated controller for steam turbine generator excitation and steam valve based on Backstepping. The main contributions are as follows.In the first part, it gives a brief introduction of power systems on the basic control problem, and the stability of power system. Then it builds the models of steam turbine generator excitation system and steam valve system, considering the uncertain parameters and external disturbances.In the second part, it designs the controller of steam valve system. The parameter projection mechanism is used to design adaptive law for the uncertain parameters. And it designs the controller based on Backsteppping for the nonlinear. Then for the interference it uses the Minimax. At last, it considers the input constraints with the switching mechanism, so the controller makes sure the input is not over the constraints..In the third part, it assumes that excitation potential is optimal in the second part. But when it designs the control of steam valve system, it may have an effect on excitation potential. So it further designs the coordinated control for generator excitation and steam valve. It uses the adaptive Backstepping and Minimax, and designs the coordinated control. Similarly, it designs the switching law for the input constraints. By contrast with the simulation curve of the traditional control, the response time is shorter, and transition process is smoother and insensitivity to interference. What’s more, the input is not over the constraints.In the fourth part, considering the state constraints, it designs the coordinated control for generator excitation and steam valve with the uncertain parameters, external disturbances and the input and state constraints, which uses the adaptive Backstepping, Minimax and barrier Lyapunov. By the simulation, the state which is restricted is not over the constraints, and the other states are all stable.Finally, the whole work of this dissertation is summarized, and an outlook on power systems is given.