Coordination Of PSVR And PSS Parameters In The Multi-machine System

Power transmission is characterized by long-distance and large-capacity,and power grid is interconnected.These characteristics bring economic benefits to system operation.But at the same time,the problems of power angle and voltage stability increasingly prominent.Improving system stability is crucial to the safe operation and development of the power grid.Power system stabilizer(PSS)is widely used to damp the low-frequency oscillation of power system.Power system voltage regulator(PSVR)is used to maintain the voltage level of the high-voltage bus of power plants,so as to improve the system voltage characteristics.In this thesis,PSVR is introduced into the multi-machine system with PSS.The effect of PSS and PSVR on power angle oscillation modes and voltage oscillation modes is analyzed by eigenvalue analysis method of the multi-machine power system.The PSS and PSVR parameters are coordinated with considering the interaction between the two types of oscillation modes,and the power angle and voltage oscillation characteristics of the system can be improved as a whole.The work completed in this thesis mainly includes the following aspects.(1)The dynamic model of the multi-machine system including PSS and PSVR control systems is established,the system state space equation is formed,and then the power angle oscillation modes and voltage oscillation modes of the system can be determined according to the eigenvalue analysis method.According to the analysis of corresponding oscillation mode,the location and parameters configuration of the controller can be carried out.(2)The phase-frequency characteristic analysis method and root locus method are adopted to set the initial values of PSS parameters.While the general method for PSVR parameter tuning has not been formed.Refer to the PSS parameter setting method,the initial values of PSVR are set.The power angle characteristic calculation method of the system is extended to the dynamic reactive voltage analysis.The analytical expression of dynamic voltage characteristics is deduced by using the sixth-order equation of generator,and the initial values of PSVR time constants are set according to the voltage phase-frequency characteristics.The initial values of gain coefficients are selected according to the root locus of the corresponding voltage oscillation mode.(3)With gain coefficients and time constants of PSS and PSVR as control variables,the stability indices of power angle oscillation modes and voltage oscillation modes as optimization objectives,and the permitted range of controller parameters as the constraint condition,the joint optimization model of PSS and PSVR parameters in the multi-machine system is established.The interaction among multiple PSSs and PSVRs can be taken into account by the proposed method,and the power angle and voltage oscillation characteristics of the system can be improved as a whole.The optimization model is solved by nonlinear programming method,and the different calculation methods of the objective function gradient in the iterative process are compared and analyzed.(4)The controller parameters optimization algorithm is implemented by using Fortran language programming of Intel(R)Visual Fortran Composer XE 2011 version.Two examples of eight-machine system and an actual system are used to further verify the feasibility and effectiveness of the parameters coordination method.