Dynamic voltage restorer control using bi-objective optimisation to improve power quality´s indices

Dynamic voltage restorer (DVR) is one of the custom power devices for compensating power quality indices which is used. The main function of DVR that is discussed in many studies is to compensate voltage sag at times when faults occur. For the first time, a new control structure is presented for considering the voltage sag as the main objective and voltage total harmonic distortion (THD) as the second objective of DVR controller. In this strategy, a new and powerful optimisation algorithm (known as chaotic accelerated particle swarm optimisation (CAPSO)) which is an improved version of particle swarm optimisation algorithm is used for determining the coefficients of the proportional-integral controller of DVR. These coefficients are determined in a way that voltage sag is considered as the main objective of optimisation algorithm and voltage THD is considered as its second objective. By fuzzifying the objectives, an appropriate objective function is proposed for the optimisation process. Results obtained from simulation and a comparison made between these results and those of other controllers show that the proposed strategy outperforms other strategies.