Engineering, Technology & Applied Science Research Vol. 7, No. 3, 2017, 1732-1736 1732 www.etasr.com Bharti et al.: Controller Design of DFIG Based Wind Turbine by Using Evolutionary Soft Computational … Controller Design of DFIG Based Wind Turbine by Using Evolutionary Soft Computational Techniques Om Prakash Bharti Dpt of Electrical Engineering Indian Institute of Technology Banaras Hindu University Varanasi-221005, (U.P), India opiitbhu@gmail.com R. K. Saket Dpt of Electrical Engineering Indian Institute of Technology Banaras Hindu University Varanasi-221005, (U.P), India rksaket.eee@iitbhu.ac.in S. K. Nagar Dpt of Electrical Engineering Indian Institute of Technology Banaras Hindu University Varanasi-221005, (U.P), India sknagar.eee@iitbhu.ac.in Abstract—This manuscript illustrates the controller design for a doubly fed induction generator based variable speed wind turbine by using a bioinspired scheme. This methodology is based on exploiting two proficient swarm intelligence based evolutionary soft computational procedures. The particle swarm optimization (PSO) and bacterial foraging optimization (BFO) techniques are employed to design the controller intended for small damping plant of the DFIG. Wind energy overview and DFIG operating principle along with the equivalent circuit model is adequately discussed in this paper. The controller design for DFIG based WECS using PSO and BFO are described comparatively in detail. The responses of the DFIG system regarding terminal voltage, current, active-reactive power, and DC-Link voltage have slightly improved with the evolutionary soft computational procedure. Lastly, the obtained output is equated with a standard technique for performance improvement of DFIG based wind energy conversion system. Keywords-DFIG; Wind turbine; PID controller; Matlab; Simulink; model; PSO; BFO; Fitness; function Abbreviations: DFIG: Doubly Fed Induction Generator PID: Proportional Integral Derivative PSO: Particle Swarm Optimization BFO: Bacterial Foraging Optimization WECS: Wind Energy Conversion Systems WRSG: Wound rotor synchronous generator PMSG: Permanent magnet synchronous generator SCIG: Singly excited induction generator. I. INTRODUCTION Wind power is considered probably the optimum available renewable energy sources and has widely developed in recent years due to its advantages such as low pollution, comparatively low capital cost involved and the short gestation period [1]. There have been several types of generators for wind energy conversion configuration. The older approach involved synchronous generators whereas the recent approach focuses more on induction generators of different types [2]. Simple induction generators have a few weaknesses such as reactive power utilization and unregulated voltage profile during variable rotor speed. These problems can be solved by employing power electronic converter or regulators. The DFIG is a wound rotor induction machine that can operate in super- synchronous and sub-synchronous manner. The benefits of the DFIG as compared with fixed speed generators are that they improve power quality, reduce mechanical stress and fluctuations and exhibit excellent power imprisons [3]. The function of the DFIG associated with the grid is facilitated through a rotor as well as a network side converter. However, an inverter related to the rotor side is used to provide give a fundamental frequency to sustain stator frequency at an invariable stage, despite the variations in mechanical power. The control of DFIG presents a dual dilemma: to balance the velocity changes and reactive power. In reality, DFIGs should be cut off from the network while the voltage inequity is more than 6% [3]. It has been described that the torque pulsation could be concentrated by using injected recompense current in the DFIG rotor. In [4], authors presented a relevant study of a simplified model, in which the authors compare the fifth plus third order model of DFIG followed using the investigation under faulted circumstances. However, in [5], authors offered magnitude along with frequency control of network associated DFIG based on a coordinated model for wind power production [5]. The numerical differentiation based additive model approximately the nominal working position of DFIG was used. The effectiveness of such type models can be validated from the outcomes offered. The ranking of wind turbines from 800kW to 3 MW but wind farm assortment is 2MW to 200MW [7]. In this paper, we provide an alternate technique to design a controller for the DFIG system considered by [7, 8] using two bioinspired techniques. The obtained results are compared with existing solutions. The implementation of DFIG for voltage regulation at a remote location has been described in a previous work [21]. The global trend toward clean energy is an inspiration for more integration of wind-based electrical energy in power systems [9]. Vast and small wind turbines produce electrical energy for networks whereas they sustain stand-alone isolated areas like well [10]. However, the wind velocity changes radically depending on the environmental circumstances along with the time of operation. Therefore, there is a huge margin of speed difference. Such margins of speed alteration make the wound rotor induction machines appropriate for power Engineering, Technology & Applied Science Research Vol. 7, No. 3, 2017, 1732-1736 1733 www.etasr.com Bharti et al.: Controller Design of DFIG Based Wind Turbine by Using Evolutionary Soft Computational … generation through wind energy [11]. Wind turbines can run either at fixed speed (actually within a speed range about 1 %) or at varying speed [12]. For fixed speed wind turbines, induction generator is instantly coupled to the grid. Hence, for a fixed-speed system, the turbulence of the wind will result in power fluctuations, which influence power quality. Power electronic apparatus are used to control the DFIG based variable-speed wind turbine. DFIG based wind turbine aerodynamics has thoroughly been described in [13-16, 17]. II. GENERAL IDEA AND WORKING PRINCIPLE OF DFIG A part of wound rotor induction generators, also known as DFIG, is one of the most frequently used scheme in the wind energy industries [18]. Currently, these types of generators are extensively accepted as one of the appropriate wind energy conversion systems. DFIG is in nature a wound rotor induction generator, and the rotor circuit is usually controlled by electric power devices to allow variable speed operation. DFIG stator winding associated directly to the grid by a power transformer and DFIG’s power is usually ranged from a few kilowatts to several megawatts. The size for a rotor converter is about 30% of a full capacity converter. During low wind speed, more electrical energy could be acquired from a variable speed DFIG, in distinguishing with a fixed speed wind generator [2]. The advantages of using DFIG in WECS is described in [2]. Whereas in [19] DFIGs have two operating modes, in (i) mode Nr>Ns, S is –ve, then generator in super-synchronous mode and both stators, as well as rotor windings, deliver power to the grid. while in (ii) mode Nr