Optimal controller design for multilevel voltage source converter based HVDC system

In the proposed work an optimal controller is designed for multilevel voltage source converter (VSC) based HVDC system. Various converter topologies are compared based on switching losses and total harmonic distortion (THD). An Optimal topology is selected for VSC-HVDC system having minimum switching loss and harmonics. Algorithm based on decoupled current controller is employed to control both active and reactive power of VSC-HVDC in all the four quadrants. It is desirable to find the optimal value of PI controller parameters of VSC-HVDC system. It is very daunting task to find global optimal value of these parameters of PI controller using classical parameters tuning methods. Therefore a new approach based on Particle Swarm Optimization (PSO) algorithm is proposed to tune the gains of PI controllers. To verify the effectiveness of proposed method, its performance is compared with analytical method. Studies shows that the PSO algorithm based PI controller parameter tuning method given more optimized results.