Fuzzy Based Controllers for Dynamic Response Analysis of DFIG based Wind Farm
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International Journal of En gineering Trend s and Technology (IJETT) – V olume 4 Issue 6- June 2013 ISSN: 2231-5381 http://www.ijettjournal.org Page 2503 Fuzzy Based Controllers for D ynamic Response Analysis of DFIG based Wind Farm R.Vijay Veera Karthick#1 , M.Bhavani #2 #1 PG student, Dept. of Electrical and Electronics Engg., Anna University, Regional Centre Madurai, Tamilnadu, India #2 Assistant Pr ofessor, Dept. of Electrical an d Electro nics Eng g., Anna University, Region al Centre Mad urai, Tamilnadu, I ndia Abstract — The global electrical energy consumption is rising and there is steady increase of the demand on power generation. In addition to conventional power generation units a large number of renewable energy units are being integrated into the power system. The Wind Energy Conversion system (WECS) is the most cost competitive of all the environmentally clean and safe renewable energy sources in world. Doubly fed induction generator (DFIG) based wind farm is today the most widely used concept. This paper presents the dynamic response analysis ofDFIG based wind farm under remote fault condition using the fuzzy logic controllers. The goal of the work is to analyze the dynamic response of DFIG based wind farm during and after the clearance of fault using the proposed fuzzy logic controller. The stability of wind farm during and after the clearance of fault is investigated. The effectiveness of the fuzzy logic controller is then compared with that of a PI controller. The validity of the controllers in restoring the wind farms normal operation after the clearance of fault is illustrated by the simulation results which are carried out using MATLAB/SIMULINK. Index Terms —Doubly fed induction generator, wind farm, remote fault, fuzzy logic controller, simulink I.I NTRODUCTIONDue to the conventional energy sources consumption andincreasing environmental concern, great efforts have been done to produce electricity from renewable sources, such as wind energy sources.Proposals for wind developments in the hundreds of MWs are currently being considered. Interconnection of these developments into the existing utility grid poses a great number of challenges [13]. The doubly fedinduction generator (DFIG) based wind turbines are nowadays more widely used in large wind farms. The main reasons forthe increasing number of DFIGs connected to the electric gridare low converter power rating and ability to supply power at constant voltage and frequency while the rotor speed varies [8]. Improved Direct Power Control (DPC) strategy for grid- connected wind-turbine-driven doubly fed induction generators (DFIGs) when the grid voltage is unbalanced is considered. The DPC scheme is based on the sliding mode control (SMC) approach, which directly regulates the instantaneous active and reactive powers. The SMC-basedDPC during network unbalance is proposed to achieve three selective control targets, i.e., obtaining sinusoidal andsymmetrical stator current, removing stator interchanging reactive power ripples and canceling stator output active power oscillations [3]. Improved Direct power control (DPC) strategy for a doubly fed induction generator (DFIG) basedwind power generation system under unbalanced grid voltage dips is proposed. Two resonant controllers, which are tuned to have large gain at the power pulsation frequencies, are appliedtogether with the proportional-integral controller to achieve full control of the DFIG output power. The fundamental anddouble grid frequency power pulsations, which are producedby the transient unbalanced grid faults, are mathematically analyzed and accurately regulated [4]. Stability study of a variable-speed directly-driven permanently- excited 2-MW wind generator connected to ac grids of widely varying strength and very weak grids are carried out. Two alternative controller designs are studied for their potential to enhance system robustness to changes in ac grid strength [5]. Optimum design procedure for the controller used in the frequency converter of a variable speed wind turbine driven permanent magnet synchronous generator using Genetic algorithm (GA) and response surface methodology (RSM) is presented. The effective ness of the designed parameters using GAs-RSM is compared with that obtained using a generalizedreduced gradient (GRG) algorithm considering both symmetrical and unsymmetrical faults [1]. Different combinations of reactive power control of rotor- and grid-side converters are investigated for voltage-control purposes. The performance of alternative voltage control strategies applied to doubly fed induction generator (DFIG) is compared [6]. In this paper, a detailed model for representation of DFIG based wind farm in power system dynamics simulations is presented. MATLAB /SIMUL INK d ynamic software program is used for this study. This paper presents dynamic response analysis of DFIG based wind farm under remote fault conditions using the fuzzy logic controller. The goal of the work is to enhance th e dynamic response of DFIG based windfarm during and after the clearance of fault using the proposedfuzzy logic controller. II.MATHEMATICAL MODEL OF DFIGFor analysis of control strategies, the mathematical model of doubly fed induction machine, in per unit notation with motor convention in d–q r eference frame is = − + (1)
