Parameters Optimization Of New Power Systerm Stabilizer Using Improved PSO Algorithm

The application of grid interconnection,heavy-duty,fast automatic voltage regulator will reduce system damping.When the damping becomes weaker or even negative,it's easy to arise low frequency oscillation phenomenon.As the main measure to suppress low frequency oscillation,the power system stabilizer(PSS)is widely used.However,the single-branch PSS is not satisfying in model and suppression theory.The new power system stabilizer PSS4B divides the input signal into three branches,providing the appropriate compensation phase for different frequency bands.Because the parameters of three branches influence each other,there exists few researches on the parameter setting at present.Therefore,the research on PSS4B has certain practical significance.In this paper,the mechanism of low frequency oscillation and the theory of PSS suppression oscillation are analyzed first.Structure of different kinds of PSS are also introduced with their respective advantages and disadvantages,which details the PSS4B model.Based on the complete transfer function of PSS4B,some simplification is carried out,and the bandpass filter,phase compensation and gain link of each branch are the parameters to be optimized.Then the linearized models of the entire multi-machine power system and single machine infinite bus system with PSS4B are established.With the eigenvalue analysis method,program to acquire the electro-mechanical oscillation patterns,relevant factors and other variables,which provides a theoretical basis for PSS4B installation site selection and quantitative analysis of parameter optimization results.Secondly,based on the basic PSO algorithm,the random weight and hybrid operation are introduced to obtain the improved PSO algorithm.By using the benchmark function,the improved PSO algorithm is compared with other two improved PSO algorithms.Results show the improved PSO algorithm is superior in high dimensional optimization,convergence stability and accuracy.The parameters of PSS4B are optimized in two steps,first,the bandpass filter and gain link being optimized,then the phase compensation of each branch.Based on the principle of ITAE,the fitness function tracks reference value to make the system output minimized.At the same time,different typical operating conditions are considered in the fitness function,which can guarantee adequate system stability margin and improve the robustness of PSS4B.At last,eigenvalue analysis and nonlinear simulation results show that the PSS4B based on the improved PSO can suppress low frequency oscillation more quickly under different system operating conditions and improve the system's robustness effectively.