Power System Nonlinear Variable Structure Control

A new nonlinear variable structure excitation controller and steam valving controller are proposed in this paper. Design of these controllers combines the differential geometry theory with the variable structure control theory. The mathematical model in the form of "an affine nonlinear system" is set up for the control design of a single machine-an infinite bus power system and a large-scale power system. The static and dynamic performances of the nonlinear variable structure excitation controller and steam valving controller for a single machine—an infinite bus power system and a multi-machine system are simulated. The responses of system with the controller proposed are compared with those obtained with the nonlinear optimal controller when the system is subjected to a variety of disturbances. Simulation results show that the nonlinear variable structure excitation controller and steam valving controller give satisfactorily static and dynamic performances and good robustness.Power system control mode has been paid attention to and a vast amount of research work have been done to improve it. Initial control mode was so-called proportion regulation and PID regulation which are implemented according to generator terminal voltage deviation. This singer variable control mode can not effectively improve system dynamic quality and raise system stable level. Afterwards, different control theories, such as the linear optimal control mode, linear adaptive control mode and so on, have been used to design high performance power system stabilizers in the past years. Although these multivariable control modes can remarkably improve power system static stability, they can not obviously raise dynamic stable level. Since, in fact, power system is a nonlinear dynamic one, the controller designed by using the linearized model at a certain equilibrium state of the system may cause intolerable errors and even take wrong action while the state point of the power system is changed away from the equilibrium point at which the linearization is realized.In 1980s, Chinese scholars proposed a nonlinear optimal excitation and governor stabilizer based on the differential geometric linearization approach. The global...