Design Of Wide-area Damping Controller For Power System Considering Saturation

As the scale of China’s power system continues to expand,low-frequency oscillations between regions affect the stable operation of the power system,restrict the transmission capacity of the power grid,and may even cause the power system to become unstable.The development of wide-area measurement technology has resulted in the use of wide-area signals to design wide-area damping controllers.Compared with traditional PSS based on local signals,wide-area damping controllers use feedback signals from remote units for damping control,so they are more effective Suppress low-frequency oscillations in the interval.In fact,the saturation phenomenon exists in most physical systems,which transforms global progressive stability into local progressive stability,which is a relatively common control constraint in control systems.If the controller is designed without considering the saturation problem,the output of the actuator and the output of the controller will be different,which will affect the dynamic performance of the control system.For the power system,the saturation of the controller is not only for the transient stability of the power system if it has an adverse effect,it may also interfere with the power system and affect its static stability.Therefore,designing the anti-saturation compensator to compensate the saturation of the controller is of great significance to maintain the performance of the controller.It can ensure that the controller can ensure the stability of the system even when saturation occurs.This paper focuses on the saturation problem of wide-area damping controllers in power systems.The main research work is as follows:First,a nonlinear model of the power system is established and then linearized to obtain the linearized state-space equation of the system.On the basis of this,the saturation link is considered,and a power system model considering the influence of saturation is established.Based on the residue matrix method,the installation location of the wide-area damping controller is determined and a suitable wide-area signal is selected.Select the appropriate weight function to shape the controlled power system so that the open-loop gain of the system after shaping meets the expected value.Based on the robust controller theory,the wide area H controller is designed to improve the power system damping and improve the stability of the power system.In view of the difficulty in selecting the weight function for loop forming,this paper uses an intelligent optimization algorithm to optimize the weight function.Based on the traditional particle swarm optimization algorithm,in order to improve the local and global search capabilities,the operation of the simulated annealing algorithm and the cross mutation operation of the genetic algorithm are introduced,and then an improved particle swarm algorithm is proposed to shape the expected the performance of the system is the objective function.The parameters of the weight function are optimized.The simulation proves that the weight function selected by this method can meet the expected performance requirements better than the traditional weight function selection method.The designed controller has the best performance the control effect can significantly improve the system damping.Aiming at the saturation link of the controller,this paper uses the "two-step method" to design the anti-saturation compensator based on the Lyapunov stability theory.On the basis of the linear controller designed under ideal conditions,an anti-saturation link is added.The anti-saturation compensator is designed an d the error between the actual output signal after the controller is saturated and the ideal output signal when there is no saturation is the input of the compensator is used to compensate the influence of the saturation link on the performance of the controller.The simulation results show that the anti-saturation compensator involved can effectively compensate the saturation link,so that the control performance of the controller is not much different from that of the ideal controller,and the control performance of the controller is effectively improved.