Design On Excitation System And Research On Active Disturbance Rejection Control

The excitation control system of generators, as an important component which has direct impact on the operating characteristics of the generators, is of remarkable significance for the safe and stable operation of electrical systems. With the change of the structure of demand on energy and power on a global scale and the rapid development of renewable energy technologies, PWM rectification technology has gradually become a research focus in the electric power technology and the conventional SCR phase-controlled rectifier is being replaced by PWM rectifier imperceptibly. PWM rectifier can make the current of drift-net side become sinusoid and make power factor up to one, provide quick dynamic response, enable bidirectional power flow, increase power supply quality, extend the life span of generators and realize the combination of energy saving and environmental protection. Therefore, it is valuable to apply the PWM rectifiers in the excitation control systems.In this background, an open-loop stable excitation control system of micro-turbine and an open-loop unstable excitation control system of asynchronous generators are selected as the subjects for research and design.Firstly, by elaborating the important role that excitation control systems have in electric power systems and choosing micro-turbine as the object of research, the excitation control system is studies in overall. In order to achieve expected control results, some electric circuits have been modified, including DC sampling electric circuit, frequency sampling circuit, insulation resistance measurement electric circuit and phase sequence detection circuit. Besides, the ideal control results are obtained by the simulation of several electric circuits.Next, the excitation control system of automobile asynchronous generators is the object of study. By the modelling of asynchronous motors and the earnest analysis on the automobile excitation control system, the voltage regulator is researched and designed. And some problems in the process of designing are solved and summarized, which is of practical value for the studies and applications of relevant projects in the future.At last but not least, based on the adequate control results attained in the application of PID controller running in the actual operation of micro-turbine, in consideration of the nonlinear property and time-varying property of the controlled plant, active disturbance rejection control strategy is proposed. And a second order active disturbance rejection controller is researched, designed and applied in the excitation control system of generators. By means of simulation, it is proved that the active disturbance rejection controller has an excellent adaptability and robustness under modeling uncertainty and disturbances, compared with the PID-based excitation controllers of generators.