Improved Power Quality for Renewable Power Generation Systems Presence of Non-Linear Loads

Improved Power Quality for Renewable Power Generation Systems Presence of Non-Linear Loads
Authors:A. NAGENDRA BABU, M. RAMA MOHAN RAO

Abstract: The performance analysis of four-leg voltage-source inverter using a Fuzzy logic control scheme is presented. The use of a four-leg voltage-source inverter allows the reduction of current harmonic components, as well as unbalanced and Negative sequence currents generated by single-phase nonlinear loads. A comparison of the proposed method against the conventional proportional integral is illustrated with inverter topologies through simulation results and a clear advantage of the fuzzy logic control can be observed. 

Keywords: Active Power Filter, Current Control, Predictive Control, Four-Leg Converters, Fuzzy Controller.

INTRODUCTION 

       DG’s affects power quality due to its nonlinearity. The non-uniform nature of power generation directly affects voltage regulation and creates voltage distortion in power systems. This new scenario in power distribution systems will require more sophisticated compensation techniques. Although active power filters implemented with three-phase four-leg voltage-source inverters (4L-VSI) have already been presented in technical literature. The primary contribution of this paper is Fuzzy logic controller designed and implemented specifically for this application. Traditionally, active power filters have been controlled using a predictive control technique, such as fuzzy logic or adaptive, for the current as well as for the dc-voltage loops. Fuzzy controllers use the non-linear model, which is closer to real operating conditions compare to predictive control. An accurate model obtained using fuzzy controller improves the performance of the active power filter, especially during transient operating conditions, because it can quickly follow the current-reference signal while maintaining a constant dcvoltage. The mathematical model of the 4L-VSI and the principles of operation of the proposed predictive control scheme, including the design procedure. The complete description of the selected current reference generator implemented in the active power filter is also presented.

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