Analyzing and Mitigating Power Quality Problems of Grid-Connected Wind Energy Systems

Abstract

To meet the excessive demand of electric power and maintain a sustainable development with a greener world, the generation system now moves to renewable energy sources. Among the renewable based distributed generation systems, the wind based one is becoming popular day by day. When the wind based distributed generation (DG) and the distributed network (DN) both are connected to establish a technologically upgraded system, then different types of power quality problems arise in the system. In this thesis, the adverse impact of the resultant harmonics of permanent magnet synchronous generator (PMSG) based wind turbine is examined from every corner and also found a perfect remedy. For pointing out the harmonics nature and magnitude of distribution systems, different types of non-linear loads, such as resistive-inductive loads, induction motor with adjustable speed drive and arc furnace are modeled. In faulty conditions, the voltage sag and swell issues are also overviewed here. In this research, an AC/DC/AC converter is designed with voltage dependent current limiter and the proposed current control mechanism of the generator’s converter is based on the straight line theory. The proposed control mechanism for designing the voltage source converter of the static synchronous compensator (STATCOM), which is connected to a battery, is governed by the pulse width modulation technique. A proper integration between these two control mechanisms creates a stable system and mitigates the power quality problems. The overall performance of the proposed model is tested on a 12 bus radial network, with designed nonlinear loads connected to it, using PSCAD/EMTDC software and afterwards laboratory tests are carried out to examine the harmonics currents and voltages. From the analysis, it is investigated that harmonic increases as the number of distributed generator increases and also in faulty conditions. Moreover, the level of harmonic varies based on the position of the wind generator and non-linear loads. The research outcome obtained from this comprehensive analysis proved that the proposed control mechanism approach is successful to eliminate and keep the voltage and current harmonics within a safe range, maintain the power system stability as well as mitigate the voltage sag and swell.