Research On Parameter Optimization Of DC Modulator Based On Cooperative Chaotic Particle Swarm Optimization

In recent years,with the increasing scale of the interconnected system,the load of the contact line is aggravated.However,China’s power interconnection system is still in the initial stage,and the remote and inter regional system links are still weak.In addition,The use of modern exciting and high top multiplier excitation systems,it weakens the damping performance of the system and leads to the emergence of negative damping,which leads to the phenomenon of low frequency oscillation between interconnected systems.The safe and stable operation of the power system is seriously threatened.But it make use of the high controllability and overload capacity of DC system in AC/DC system,the DC power modulator with DC line configuration can effectively suppress interregional low frequency oscillation of interconnected system.Rational configuration of the DC power modulator parameters is the key to ensure good DC modulation effect.The traditional method relies on the actual engineering experience value or the simulation value to design parameter,the parameter values only apply to a particular system.It may weaken the modulation effect of other controllers and even deteriorate the damping performance of other modes,when some oscillation modes are damped,which even leads to system instability.Therefore,it is necessary to coordinate and optimize the parameters of each modulator in the interconnected system as a whole.The proposed cooperative chaos particle swarm optimization algorithm is applied to the design of DC modulator parameters.The algorithm adopts the premature decision strategy,and the particle swarm is divided into two groups,and the two stage is optimized.In the first stage,the PSO iteration and the chaotic iteration are carried out simultaneously,and the global extremum is updated according to the fitness value,so that the particle falls into the local optimum.In the second stage,the PSO iteration and the chaotic iteration are carried out at the same time.The PSO clustering particle is selected according to the fitness value,and chaotic optimization is carried out to help the inert particles jump out of the local optimum region.This makes use of the advantage of PSO search speed and utilizes the advantage of chaotic ergodicity.The active power change rate of the AC tie line and the change rate of generator power angle are selected to establish the performance index function,and the damping of interconnected system is considered as a whole.It can avoid the problem of weakening the damping performance of other modes.In the IEEE four machine two area and eight machine three area AC / DC transmission system,the DC modulator that has been optimized by PSO and CPSO is configured,dynamic Prony analysis and simulation results verify the effectiveness and feasibility of the proposed optimization strategy.