www.ijsetr.com ISSN 2319-8885 Vol.03,Issue.50 December-2014, Pages:10190-10199 Copyright @ 2014 IJSETR. All rights reserved. A Novel Control Strategy for Achieving Power Quality in the Grid Interconnection of Distributed Generation DEVALRAJU PRASAD 1 , G.VENKATA SURESH BABU 2 1 PG Scholar, Dept of EEE, SITS, Kadapa, AP, India. 2 Associate Professor & HOD, Dept of EEE, SITS, Kadapa, AP, India. Abstract: The grid integration of distributed generator (DG) system normally poses many connection issues leading to discouraging the use of DG. Hence a novel control strategy is presented for improving the efficient power quality to the interconnection of DG with a grid. The grid-inter facing inverter can be effectively utilized for power conditioning without disturbing its regular operation of real power transfer. The grid-interfacing inverter with the proposed approach can be utilized to: i) inject real power generated from RES to the grid, and/or, ii) operate as a shunt Active Power Filter (APF). This approach consequently eliminates the need for additional power conditioning equipment to improve the quality of power at PCC. General MATLAB/Simulink simulation as well as the DSP based experimental results have validated the proposed approach and have shown that the grid-interfacing inverter can be utilized as a multi-function device. Keywords: Active Power Filter (APF), Distributed Generation (DG), Distribution System, Grid Interconnection, Power Quality (PQ), Renewable Energy. I. INTRODUCTION The use of distributed generation (DG) sources is currently being considered as a solution to the growing problems of energy demand. Apart from the consequent reduction in the size of the generating plants and the possibility of modular implementation, DG systems based on renewable energy sources (photovoltaic, fuel cells, and storage systems such as ultra capacitors and batteries) are of great interest due to their low environmental impact and technical advantages such as improvements in voltage levels and reduced power losses when a DG system is installed in radial lines. DG systems also promote cogeneration and improve overall system efficiency. A DG system operating at high performance requires a detailed evaluation of the feeder where the DG will be installed, plus an assessment of the load type the DG must supply locally and its working regime. Without these requirements, the effects of DG may be more harmful than beneficial: the insertion of new generation sources in the distribution system may cause transient effects due to switching operations, changing short-circuit levels, lower margin of stability, and inversion of the power flow through the distribution system, causing erroneous operations of the protection devices and is landing in part of the system. In addition, the DG operation should not exceed the limits established by international standards for the following parameters: harmonic distortion, voltage imbalance, voltage fluctuations, and fast transients, whether the local load is unbalanced, nonlinear, or a dynamic load, such as a motor. Recently, the use of power or current in the d-q synchronous reference frame as control variables to Command the voltage source inverter (VSI) connected to the grid has generated considerable interest from the scientific community. With either method, before or after the contingency takes place, the control variable remains the same, making the DG operate with limited capability to supply the load. On the other hand, two control algorithms were proposed to improve the grid-connected and intentional-islanding operations methods, in which the DG system must detect the situation and switch from power or current to voltage as a control variable to provide constant rms voltage to the local loads. In the power flow is determined by controlling the amplitude and angle of displacement between the voltage produced by the DG and the grid voltage, i.e., the control variable is the same before and after the islanding mode occurs. The voltage control provides the capability to supply different kinds of loads to the DG system, such as linear, nonlinear, motor, balanced, or unbalanced, even if the DG operates in the islanding mode. These kinds of controls are suitable for DGs operating in parallel as each of the DGs are connected to the grid through a distribution transformer (DT). Conversely, the other approaches introduced are more effective. The paper is arranged as follows: Section II Power Quality Improvement at the Distribution System. Section III describes the system under consideration and the controller for grid-interfacing inverter. A digital simulation study is presented in Section IV. Extensive experimental results are discussed in Section V and finally Section VI concludes the paper.