Research On Wide-area Damping Control Of Power System And Online Coordination Optimization Of Multi-controller Parameters

The problem of low-frequency oscillation in power system has become one of the important factors affecting the safety and stability of power grid in our country.If the low-frequency oscillation is not effectively suppressed,it will threaten the stable operation of power system,and cause a large-scale blackout.There is an obvious time-delay in the transmission of wide-area signals of power system,which will have adverse effects on the design of system damping controller and coordination control.The interconnected power system is becoming more and more complex,and the number of controllers is constantly increasing.The type and the number of controllers will increase with the complexity of power grid.The interaction between controllers may be detrimental to the performance of power system,which would weak the control performance of power system.Therefore,the further study of wide-area damping control and coordination control of power system have important theoretical significance on ensuring the stable operation of power system in wide-area environment and online coordination of controller parameters.First,the problem of power system damping control without considering time-delay is studied in this paper.There is a model identification error in power system identification and control,and it will bring great difficulties to power system identification and damping control,which often deteriorates the damping control effect.To solve this problem,firstly,a closed-loop model of power system in multi-interference environment is established;Secondly,an iterative identification method is proposed based on recursive least-squares(RLS)and Vinnicombe distance theory method,and this method combines with an identification and control,and also the complete steps of the method are given.Therefore,the optimal power system model and the wide-area damping controller model can be obtained;Then the four-machine two-area system model is taken as an example;Finally,compared with the traditional iterative identification method,the proposed method in this chapter has reduced the amplitude,and the stable time is reduced by about half,and the time of rotor angle oscillation control of power system tends to be stable in about 10 seconds.Second,the wide-area damping control problem of power system considering time-delay is studied in this paper.On the basis of considering the model identification error factor,we focus on the time delay problem.First,the closed-loop time-delay model of power system is established;Second,an design method of iterative identification damping controller of power system considering the time delay(constant delay and time-varying delay)factor is proposed,and also the state feedback and the feedback gain are designed by LMI and pole placement,respectively,which can solve the problem of damping control of the power system with time delay;Then the four-machine two-area system model is taken as an example in this paper;Finally,the comparative analysis is conducted under different time-delay conditions and oscillations of rotor angle and active power can be stabilized within 8 seconds,which can effectively suppress low-frequency oscillation and ensure the stability of power system.Then,the online coordination control of multi-controllers in power system is studied in this paper.Firstly,the multi-controller parameter coordination model is given;Then,an artificial immune algorithm based on the spherical domain theory is proposed to coordinate and optimize multi-damping controller parameters online,and this algorithm can reduce the calculation complexity and has a global search capability;Finally the four-machine two-area system model is taken as an example,and compared with the dynamic index optimization method,it is concluded that the oscillation curve of active power and rotor angle using this method tend to be stable within 5 seconds,and the amplitude is also reduced by about half.This algorithm can more effectively achieve the coordination and optimization of multi-controller parameters,and the control effect of power system is improved.Finally,RTDS experimental equipment to verify the proposed theory is used in this thesis,and experimental results are basically consistent with simulation results.All algorithms designed algorithm in this paper can effectively suppress low-frequency oscillation.Simulation and RTDS experiments show that the designed controller considering the model identification error factor can effectively suppress low-frequency oscillation of power system;And also parameters coordinated online by the sphere artificial immune algorithm can effectively suppress the low-frequency oscillation of power system.Both the simulation and the experiment have achieved good wide-area damping control effects,which can provide the theoretical and technical support for the wide-area damping control in China Southern Power Grid.