Research On Optimization Of PSS Parameters Based On Improved Bat Algorithm

With the increasing expansion of electric power system,as well as the adoption of the high magnification of fast excitation system in the large generator,the power system often produce low frequency oscillation,this usually makes the system damping have a lager weakened.Besides it has a great effect to the dynamic stability of power system.Therefore,the low frequency oscillation has become the important factor which seriously restricts the development of the power system further.The excitation system with PSS as an additional device is widely used to suppress low frequency oscillation.PSS is used to control the generator excitation to improve local mode oscillation damping,studies have demonstrated that resonable setting of PSS parameters can improve the local mode and the inter-area mode oscillation damping.However,because the negative damping effect of PSS may be exist in the multimachine system,so the configuration of PSS parameters configuration is a multi-parameter optimization problem.In order to suppress the low frequency oscillation in multimachine power system,a kind of IBA algorithm is proposed in this thesis which is used to coordinate and optimize the parameters of PSS,which is based on the analysis of the shortcomings of of some commonly-used algorithms for PSS parameters optimization.BA algorithm is a new intelligent optimization algorithm based on global search and local search,in which the echolocation of the bat is dealed with mathematical methord.The algorithm have high accuracy and efficiency and it has been applied to solove a variety of complex functions and muti-objective optimization,and BA algorithm has been applized in many engineering problems.In addition,the Prony algorithm based on comparison and research on low frequency oscillation analysis is determined,and applied in an example simulation.The results show that the Prony algorithm is efficiency in analyzing the low-frequency oscillation problem.Thefore,firstly,Prony algorithm is used to identify the electromechanical modes of low frequency oscillation in this thesis,and calculate the damping ratio which can reflect the damping level of multi-machine system,and the purpose of optimization is to maximize the system damping ratio,secondly,the IBA algorithm is applied to optimize PSS parameters.Finally,the rationality of the algorithm is vertified by an example,results show that the IBA algorithm can be effectively applied to the parameter optimization of damping controller under various operating conditions,and it has good robustness and can effectively suppress low frequency oscillation.In addition,by comparing the optimization results of PSS parameters of the multi machine power system based on the IBA algorithm,the PSO algorithm and the basic BA algorithm,it can be known that the PSS based on the IBA algorithm has the best effect in suppressing low frequency oscillation,and this algorithm overcomes the shortcomings of the basic BA algorithm which is easy to fall into local optimium,and slow convergence etc.