International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014 Design, Modelling, Simulation and Analysis of V/F Controller for WECS Sunam,Dr.Shantharam , Mr. Raghvendra ℎ , M.Tech Student.,Dept of ECE, Canara Engineering Collage, Manglore, Karnataka, India 2 H.O.D,ECE Department, Canara Engineering Collage, Manglore, Karnataka, India 3 Professor , ECE Department, Canara Engineering Collage, Manglore, Karnataka, India 1 Abstract-- Wind power generation has experienced a tremendous growth in the past decade, and has been recognized as an environmentally friendly and economically competitive means of electric power generation. A wind turbine can be designed for a constant speed or variable speed operation. Variable speed wind turbines can produce 8% to 15% more energy output as compared to their constant speed counterparts, however, they necessitate power electronic converters to provide a fixed frequency and fixed voltage power to their loads. Both voltage source voltage controlled inverters and voltage source current controlled inverters have been applied in wind turbines. This paper deals with the design, modeling simulation and analysis of voltage –frequency controllers for variable speed wind turbine using MATLAB/SIMULINK I. WIND ENERGY CONVERSION SYSTEM(WECS) The major components of a typical wind energy conversion system include a wind turbine, generator, interconnection apparatus and control systems. The wind rotor, being the driving component in the conversion system, converts the wind energy into mechanical energy. In the case of variable speed wind turbines an electronic inverter absorbs the mechanical power from the rotor, converting it into electrical energy, which is then fed into a supply grid. Keywords: PMSG, wind turbine, IGBT diodes ,transformer INTRODUCTION There has been a huge increase in energy demand during the last few decades. The asynchronous generators and synchronous generators such as permanent magnet synchronous generator (PMSG) are used for standalone power generation. . Such distributed isolated systems require energy storage systems usually batteries to stabilize the voltage and frequency. Recently, voltage source converter (VSC) based controllers are reported for voltage and frequency control of PMSG generator based wind energy conversion system. The voltage can differ from its nominal conditions in a many various ways, including changes in magnitude, frequency, RMS and continuity of supply. For 50 Hz systems the standard voltage recommended by IEC Publication 38 is 230/400V.The main cause of voltage variations in the grid are changes in the power system load and in power production. The wind turbine power may momentarily go from zero to maximum under strong wind conditions, or from nominal power to zero in the event of an emergency stop. Voltage and current harmonics and inter harmonics are always present on the utility grid. In case of a sudden wind blow or wind drop the small spinning reserve will bring rise to frequency fluctuations. ISSN: 2231-5381 Fig.1. Block diagram of WECS A Modelling equations of the WECS The proposed WEC system consists of a wind turbine, a permanent magnet synchronous generator, a VF controller and a ripple filter and these components are modeled in the following section. If ρ is the specific density of air (m3/s), A is the swept area of the blades (m2) ,V is the wind speed (m/s), the power coefficient is ,the aerodynamic power of the wind turbine can be expressed as, P = 0.5ρAC V (1) ω λ is a function of tip speed ratio and is obtained as, = where λ is the angular speed of the turbine with radius R. The ω is obtained from the speed of the wind turbine. = = − − , http://www.ijettjournal.org + =0 Page 141 International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014 II. VF CONTROLLER 2. The proposed voltage and frequency controller consists of an insulated gate bipolar junction transistor based voltage source converter along-with battery energy storage system at its dc link. The proposed controller is having bidirectional active and reactive powers flow capability by which it controls the system voltage and frequency with variation of consumer loads and the speed of the wind turbine[1]-[3]. When there is variation in wind speeds and corresponding variation in the machine speed, the battery and consumer loads absorb such amount of power by which desired frequency of the generated voltage can be achieved. It is also having capability of harmonic elimination and load balancing. The frequency controller is done by extracting active component of the source current. A. MODELING OF THE CONTROL SCHEME Basic equations of the control scheme of the proposed controller are as follows. 1. Computation of Active Component of Reference Source Current Active component of reference source current is estimated by dividing the difference of filtered instantaneous load power ( )and output of the PI frequency controller to the terminal voltage ( = ( + + ) ). Computation of Reactive Component of Reference Source Current The instantaneous quadrature components of reference source currents are estimated as = ; = ; = , is obtained by output of the voltage PI controller where input is voltage error between reference ac terminal voltage ( )and ( )at the terminals of generator where, = 3. √ + √ , = √ + ( ) √ , √ = + ( ) √ . Computation of Reference Source Current Total reference source currents are sum of in-phase and quadrature components of the reference source currents as = + , = + , = + . 4. PWM Signal Generation Reference source currents( , , ) are compared with sensed source currents ( , , ) The current errors are computed as = − , = − , = − . These the amplified signals are compared with fixed frequency (10 kHz) triangular carrier wave of amplitude to generate gating signals for IGBTs of VSC of the controller. IV. FUTURE WORKS V/F controller can be implementing for wide range of The load power ( ) is = + , It is wind speed. We can design different types of v/f controllers and filtered to achieve its dc component ( ),Where( , ) can analyses which can provide good controlling scheme, in turn ,( , )are obtained by three phase to two phase transform of we can implement in the WECS. ac load voltage , , & ac load currents , , .Then active component of reference source current is calculated as V. SIMULATION RESULT AND ANALYSIS =2 The dynamic performance of the WECS with PMSG and VF controller under varying wind is shown in Fig. 3. where ( )obtained by output of the of the frequency proportional integral (PI) controller. Input to the controller is The wind speed can increase from 9 to 10m/s. During the the frequency error between reference frequency and the system interval we are getting constant voltage and frequency. This , frequency. Instantaneous values of in-phase components of obtained by the PWM signal. The source voltages source currents (Is), load currents ( ), load voltage reference source currents are estimated as controller pulse, system frequency (f), wind power ( ) , = ; = ; = where PMSG speed = ; = ; = . ( rad /min) and load power (PL) are depicted in Fig. 3. It is observed that the change in source power due to the change in wind speed is absorbed by the controller to maintain the system frequency to the reference value. The amplitude of terminal voltage is maintained at the reference value under various load disturbances. Fig 2: v/f controller ISSN: 2231-5381 http://www.ijettjournal.org Page 142 International Journal of Engineering Trends and Technology (IJETT) – Volume 12 Number 3 - Jun 2014 Fig 3 : Result. V. REFERENCES [1]Bhim Singh, Senior Member, IEEE, and Gaurav Kumar Kasal-Voltage and Frequency Controller for Three-Phase Four-Wire Autonomous Wind Energy Conversion System [2] Dr. Bhim Singh Fellow IEEE, IET, INAE, IETE, IE (I), INSc Stand-Alone Wind Energy Conversion Systems [3] Bhim Singh, Shailendra Sharma -Neural Network Based Voltage and Frequency Controller for Isolated Wind Power Generation [4] M. E. Haque University of Tasmania-Control of a standalone variable speed wind turbine with a permanent magnet synchronous generator mehaque@utas.edu.au APPENDICES A. Wind Turbine Specifications R=5.78m,C1=0.5176,C2 =116, C3 =0.4, C4 =5, C5=21,C6=0.0068,C7=0.08,C8=0.035 B. Permanent Magnet Synchronous Generator 415V, 50Hz, 16pole R=0.03 Ω, X=2.1e-3H, J=0.7 kg-m2 C. Battery Model Specifications Cb=25000F, Rb=10kΩ , Rs=0.01Ω, Voc=400V D. Loads : 9KW,400V, 50Hz E. Frequency PIcontroller: Kp=3,Ki=150 F. Terminal voltage PI controller: Kp =0.03, Ki =0.001 G. PWM switching frequency: 10 kHz ISSN: 2231-5381 http://www.ijettjournal.org Page 143