Grid Integrated Hybrid Renewable Energy System for Power Quality Improvement Using Open End Winding Transformer

Hybrid renewable systems are emerging as a promising method for replacing the conventional fossil fuel based energy economy. Integrating more than one renewable sources increases the capacity factor of the system, reduces unpredictability and improves stability of electricity supplied. Grid integration of these systems are challenging due to the voltage and frequency regulation issues. Power quality issues like unbalance, harmonic distortions, transients etc. need to be addressed while integrating these renewable sources to the utility. This paper proposes a power quality enhancement method with the help of an open end winding transformer fed hybrid renewable system. The hybrid system combines a solar photovoltaic system with a wind power plant. Active power filter based control scheme is chosen for the control of both voltage and current distortions. An open end winding transformer with open primary and star connected secondary coupled to the grid is considered. The open primary windings are supplied with two voltage source inverters which are fed with renewable energy sources. First grid-connected inverter is controlled as dynamic voltage restorer to compensate for voltage distortions. The second inverter is controlled to mitigate current distortions and also provides reactive power compensation with shunt power filter control. The proposed system is simulated and validated in MATLAB/Simulink and shows that the system minimizes the harmonic distortions within the standard limits.