Research On Excitation Control System Of Small Hydropower Self-shunt Excitation Generator

As the world energy diversity,advocating green and sustainable energy development has become the dominant trend.Small hydropower resources isvery abundant in the world.That China has proven the development of small hydropower is128 million kW.By the end of 2015,Small hydropower installed capacity has reached more than 75 million kWin our country.Itsdevelopment rate is only 58.6%.Small hydropower development potential is still great.Small hydropower has the advantages of low risk,low investment,stable efficiency,relatively low operating cost,and also can solve the problem of electricity in rural areas.Due to these advantages,our country vigorously support the development of small hydropower green energy.At present,there are some problems such as reactive power shortage and power is difficult to be sent out,which are closely related with the excitation system.Excitation controller can flexibly regulate small hydropower generator system,so the study of small hydropower excitation systems controller for self-shunt excitation generator has a certain practical significance and value.Firstly,the definition,characteristics and classification of small hydropower are introduced.The development status of excitation controller and modeare researched.The important function of the excitation controller is analyzed.It is concluded that the small hydropower has a unique advantage and the important position of the excitation controller in the power system.Secondly,the basic requirement and principle of excitation controller is analyzed.Advantages and disadvantages of self-shunt excitation system are summarized.Then the mathematical model of excitation system and single machine infinite system is established.It lays the foundation for the later establishment of the simulation model.Thirdly,the principle of PID control is analyzed,the method of setting parameters of PID control is studied,several common PID models are discussed.The benefit of PSS in power system is highlighted,and the transfer function of PSS is deduced.According to the related parameters of XiaoDongjiang No.2 machine,the simulation model of 7MW PID excitation controller and AVR+PSS excitation controller were established.The relationship and difference between the PID control and the application of AVR + PSS control had underscored,so that obtained the basic conclusion that the AVR + PSS control is based on the PID control with PSS auxiliary part.Finally,the basic thought and principle of linear quadratic optimal control was introduced,the mathematical model of linear quadratic optimal controller was deduced.According to the parameters of XiaoDongjiang No.2 machine,the linear quadratic optimal control parameters of the excitation controller was designed,and the simulation model of 7MW self and shunt excitation controllerwith linear quadratic optimal control was established.To verify the control effect of the controller design,the three kinds of controllerwere simulated by using MATLABunder large and small two perturbations.And recordedthe fluctuations of the electromagnetic power and rotate speed of generator,so it was obtained the conclusions that linear optimal controller has better dynamic characteristics and control characteristics,while PID controller has the worst dynamic characteristics and control characteristics.