Power Quality improvement in Grid connected Renewable Energy Sources at the Distribution level

Abstract

Around the world, conventional power system is facing the problems of gradual depletion of fossil fuel resources, poor energy efficiency and environmental pollution. These problems have led to a new trend of generating power locally at distribution voltage level by using non-conventional/ renewable energy sources like natural gas, biogas, wind power, solar photo voltaic cells, fuel cells, combined heat and power (CHP) systems, micro turbines, and stirling engines, and their integration into the utility distribution network. The above renewable energy sources are interconnected using various power electronics converters. Generally current controlled voltage source inverters are used to interface the intermittent RES in distributed system. This paper provides control strategy for grid interfacing inverters when installed in three phase four wire distribution system. The interfacing inverter can be utilized to inject power generated from RES to the grid and act as Active power filter to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. By this novel control strategy, the combination of Grid-interfacing inverter and the 3 phase 4-wire linear/non-linear unbalanced load at the point of common coupling appears as balanced linear load to the grid. This control concept is demonstrated with the help of simulation using MATLAB/Simulink for non-linear load and validated through digital signal processor – based laboratory experimental results.