Design Of Backstepping Control For Synchronous Generator Excitation System With Output Constraints

The speed stability of synchronous generator is one of the basic conditions for normaloperation of the power system. Its stability depends largely on the performance of excitationcontrol system. Synchronous generator excitation system is able to adjust the output powerwith a small unit power. Excitation control system has been widely concerned because of itsrapid response performance and low control cost. The actual power system has certaintolerance for the amplitude of the oscillation of generator power angle. If it excesses this limit,the generator may lose synchronization, which will lead to the power system instability oreven collapse. So the study of the problems of power angle constraint is of great significanceto the stable operation of power system.This paper studies the transient stability problem of single machine infinite bus powersystem with the excitation system. Nonlinear excitation controller is designed based onLyapunov theory and backstepping method. Considering the fact that with the actualsynchronous generator disturbance, the power angle will oscillate, the system must enable thegenerator not to loss synchronization during the process of generator oscillation, we mustensure that the generator power angle in a certain range. First of all, a Lyapunov energyfunction with a constraint function is constructed to solve the oscillation range of angle. Thennonlinear Excitation controller with output bounded is constructed with backstepping method,which not only ensures the stability of the closed-loop control system but also makes thesystem power angle output remained in the constraint set within the scope. Based on thenonlinear excitation controller design, in the process of accession to the K-class function, theimproved nonlinear excitation controller is designed, which not only guarantees the systemoutput power angle is in constraint but also makes the state convergence speed faster,oscillation amplitude smaller. Besides, considering that the damping coefficient is not easy tomeasure accurately in actual power system, so it can be regarded as uncertain parameters. Theconstrained adaptive controller design is designed combined with the adaptive method, finallythe sliding technology is introduced to redesign for parameters uncertainty system. Then wecan get the conclusion that the parameters of constrained sliding mode adaptive controller canbe adjusted nimbly in the design process. Its transient response is much faster. Simulationexperiments are done on the controller designed in the paper. The simulation resultsdemonstrate the effectiveness and superiority of the designed controller.