Wind Energy Conversion Scheme Research Articles

Improvement of Dynamic Performance in SEIG WECS by Using ANFIS Controller

A new hybrid controller for the Self-Excited Induction Generator (SEIG) driven by the Wind Energy Conversion Scheme (WECS) was proposed in this paper. The dynamic stability of the control grid is essential for both user protection and system performance. There must be a full grasp of the effects of power system volatility to research and govern power systems. The suggested control systems were examined using frequency-domain approaches that focused on the nonlinear design of a device that is subjected to severe faults on a related bus, which was tested using time-domain strategies. In this paper, a novel 3-level inverter is designed and controlled by the ANFIS control for the Dynamic Response of the system at the load side. The ANFIS approach can be used to regulate a self-excited induction generator in this study. The design incorporates wind power to give on-grid electricity access. SEIGs are used to power wind turbines in this project, which generates alternating current (AC) for the grid. The system model uses a rotor reference frame and dynamic vector control for the machine reference model. Wind power voltage and active power are controlled by an ANFIS controller in the converter. The ANFIS controller's performance is evaluated in all abnormal scenarios, including the worst-case scenario. System modeling and simulation in Simulink-Matlab allow it to be used in SEIG configurations. Wind power system quality and stability are both improved by the ANFIS control unit, according to simulation results.

Recent Trends of Control Strategies for Doubly Fed Induction Generator Based Wind Turbine Systems: A Comparative Review

There is always, a strong expectation from wind generation system to harness maximum power as well as to have good interaction with the grid. To satisfy the increasing need of power, use of a wind generation system with enhanced control is a nifty result. The wind power generation system needs a more sophisticated, novel and robust control methodology to cater the stability and efficiency improvement. The researchers are always working on the challenges present in the wind energy conversion scheme to improve its operation. This review paper provides a survey of wind turbine control system practices and controller trends specific to doubly fed-induction generator. This work will be helpful in experimental research work. Most recent and current trends like soft computing techniques and fractional order control with real time implementation are discussed as they are gaining the attention of the research community.

Cost Effective Wind Energy Conversion Scheme Using Self-Excited Induction Generator

This paper describes a laboratory model of a wind energy conversion scheme (WECS) using conventional cage rotor type induction motor of 3Hp, 3-Ø, 415V, 4.9A, 1440 rpm. A 220V, 20A separately excited motor coupled with the induction motor emulates the wind turbine characteristics. A 3-Ø, 415 V capacitor bank of 150μF is connected in each phase across the stator terminals of the machine for its self-excitation. As soon as rotor speed exceeds synchronous speed of the machine, it will generate electrical power and reach its rated value. This arrangement is called as self-excited induction generator (SEIG). To control the frequency of generated voltage, load-balancing technique is considered by using a three-phase diode rectifier powering to an additional load (dump load) through a d.c chopper circuit. Static reactive volt-ampere compensator (STATCOM) is used to mitigate the load reactive power requirement indeed magnetic reactance changes in the machine. Owing to cost optimization of STATCOM, additional reactor is connected across the stator terminals of the SEIG. Simulation study is completed using power system toolbox Matlab / Simulink version9.0. Experimental and simulation results are presented.

Genetic Algorithm-Based Fuzzy Controller for Improving the Dynamic Performance of Self-Excited Induction Generator

This paper introduces a new hybrid controller using artificial intelligence (AI) techniques to improve the dynamic performance of the self-excited induction generator “SEIG” driven by wind energy conversion scheme “WECS”. The hybrid AI compromises a genetic algorithm (GA) and fuzzy logic controller (FLC). The role of the GA is to optimize the parameters of the fuzzy set to ensure a better dynamic performance of the overall system. The proposed controller is developed in two loops of the WECS scheme under study. The first loop is used to regulate the terminal voltage, by adjusting the self-excitation. This controller represents the reactive power control. In this case, the FLC will utilize the error and its change in terminal voltage to regulate the duty cycle of the capacitor bank. The second loop is used to adjust the mechanical power, by adapting the blade angle of WECS. Here, the FLC uses the frequency error and its change to adjust the blade angle of the wind turbine to control the active power input. The simulation results, which cover a wide range of electrical and mechanical disturbances, depict the effectiveness of the proposed controller compared with other AI techniques.

IMPROVED GENERATION QUALITY OF AN ISOLATED WIND DRIVEN INDUCTION GENERATOR USING ARTIFICIAL NEURAL NETWORK

This paper presents the improvement of generation quality for a wind energy conversion scheme using artificial neural network (ANN). High generation quality means that, the induction generator generate voltages and frequency at nominal specified values, under all operating conditions, determined by various wind speeds and loads. The scheme consists of a three-phase induction generator driven by a horizontal axis wind turbine and interfaced to an isolated load. A static VAR compensator (SVC) is connected at the induction generator terminals to regulate its voltage. The mechanical power input is controlled by regulating the blade pitch-angle. Both blade pitch-angle and firing angle are adjusted using an ANN to improve the generation quality for a wind energy conversion scheme. The proposed ANN training is based on suitable values of SVC firing angles and blade pitch-angles of the wind turbine, for achieving a high generation quality at different operating conditions. The training data is obtained by using Newton-Raphson method to generate voltages and frequency at nominal specified values. The simulation results prove that, the wind energy conversion scheme, with the proposed ANN, gives good power generation quality over wide range of wind speeds and loads.

Optimal Control of Matrix-Converter-Based WECS for Performance Enhancement and Efficiency Optimization

This paper describes a new wind energy conversion scheme, where fuzzy logic principles and four-leg-improved novel matrix converter (MC) model are used for performance enhancement and efficiency optimization, particularly for sites where most of the time low wind speeds prevail. The MC is intended as the interface medium between the induction generator and the utility grid. The power factor at the interface with the grid is controlled by the MC to ensure purely active power injection into the grid for optimal utilization of the installed wind turbine capacity. The generation system has fuzzy logic control with vector control in the inner loops. Fuzzy controller tracks the angular frequency with the wind velocity to extract the maximum power and programs the machine flux for light load efficiency improvement. The complete control system has been developed, analyzed, and validated by simulation study.

Optimal control of matrix converter based WECS for performance and stability enhancement at low wind speeds

In this paper, optimal control of new wind energy conversion scheme where four-leg improved matrix converter (MC) is used for performance and stability enhancement, particularly for sites where most of the time low wind speeds prevails, has been explained. The power factor at the interface with the grid is controlled by the MC to ensure purely active power injection into the grid for optimal utilisation of the installed wind turbine capacity. The generation system has fuzzy logic control with vector control in the inner loops. Fuzzy controller tracks the angular frequency with the wind velocity to extract the maximum power and programs the machine flux for performance, stability and efficiency enhancement during light load and low speeds. The complete control system has been developed and analysed using MATLAB/Simulink.

Genetic Algorithm Based Control System Design of a Self-Excited Induction Generator

This paper presents an application of the genetic algorithm (GA) for optimizing controller gains of the Self-Excited Induction Generator (SEIG) driven by the Wind Energy Conversion Scheme (WECS). The proposed genetic algorithm is introduced to adapt the integral gains of the conventional controllers of the active and reactive control loop of the system under study, where GA calculates the optimum value for the gains of the variables based on the best dynamic performance and a domain search of the integral gains. The proposed genetic algorithm is used to regulate the terminal voltage or reactive power control, by adjusting the self excitation, and to control the mechanical input power or active power control by adapting the blade angle of WECS, in order to adjust the stator frequency. The GA is used for optimizing these gains, for an active and reactive power loop, by solving the related optimization problem. The simulation results show a better dynamic performance using the GA than using the conventional PI controller for active and reactive control.

ROBUST CONTROL OF A WIND DRIVEN INDUCTION GENERATOR CONNECTED TO THE UTILITY GRID

This paper investigates the use of the linear quadratic Gaussian controller to control the voltage and frequency of a wind energy conversion scheme. This scheme cosists of a wind turbine and induction generator connected to the utility grid via AC-DC-AC asynchronous link. The control objective aims to regulate the rectifier output voltage and track the maximum available wind power. This is accomplished via controlling the firing angles of the rectifier and the inverter. The complete nonlinear dynamic model of the system has been described and linearized arround an operating point. The standard Kalman filter technique has been employed to estimate the full states of the system. The computational burden has been minimized to a great extent by computing the optimal state feedback gains and the Kalman state space model off-line. The proposed controller has the advantages of robustness, fast response and good performance. The wind energy scheme with the proposed controller has been tested through a step change in wind speed. Simulation results show that accurate tracking performance of the proposed wind energy scheme has been achieved. Moreover, this scheme is robust against the parameters variation and eliminates the influence of modeling and measurement noises.

Novel STATCOM controllers for voltage stabilisation of wind energy scheme

This paper presents two novel dynamic controllers for the Static Synchronous Compensator (STATCOM) device to stabilise Stand-Alone Wind Energy Conversion Systems (SWECS) using an induction generator. The unified AC system wind energy conversion scheme is connected to a hybrid electric load. The STATCOM device is modelled using the PSCAD/EMTDC software environment. Two novel dynamic controllers are validated for the STATCOM. Both are error-scaled, error-driven dynamic control schemes. The first tri-loop dynamic error-driven controller utilises the RMS load bus voltage, RMS load current and the instantaneous AC load power. The second DC voltage dynamic tracking controller is validated for voltage regulation and reactive compensation. The results demonstrated the effectiveness of the STATCOM device in stabilising the AC wind energy by insuring effective generator/load bus voltage regulation and dynamic reactive compensation.

Novel STATCOM Controllers for Voltage Stabilization of Stand Alone Hybrid (Wind/Small Hydro) Schemes

This paper presents Three novel error driven dynamic controllers for the Static Synchronous Compensator (STATCOM) Facts device to stabilize both Wind Energy Conversion stand alone systems (SWECS) as well as hybrid scheme of wind plus small hydro with employing self excited induction generator. The unified AC system of standalone wind energy conversion scheme and hybrid wind/small hydro scheme are connected to a hybrid electric load. Three novel error driven dynamic controllers are validated for the STATCOM as a voltage stabilization scheme. Two novel controller are error driven dynamic controllers with auxiliary tracking control loop. The first controller is tri loop dynamic error driven controller using the RMS Load bus voltage, RMS-Load Current and the instantaneous AC load power. The second controller is DC voltage dynamic tracking controller using the dc link capacitor voltage. The third dynamic controller is based on the decoupled (d-q) current control strategy, namely the direct and quadrature current component for the STATCOM current. The dynamic response results demonstrated the effectiveness of the STATCOM-Facts device in stabilizing both AC wind energy system and the hybrid wind/hydro scheme by ensuring effective generator/load bus voltage regulation and dynamic reactive power compensation under load, wind and other prime mover excursions.

Analysis of a variable-speed wind energy conversion scheme with doubly-fed induction generator

In the last decade, the high penetration of wind turbines into the power system has been closely related to the advancement of wind turbine technology and control. The electric system contained by a large wind turbine, as well as within an offshore wind farm with hundreds of MW power capacity, has become more and more important in the interaction between the mechanical system of the wind turbine and the main power system. Furthermore, power electronics is entering the wind turbine circuitry which improves the controllability. The work presented in this paper has the main objective of extending the ability of the existing wind turbine design tools, in order to simulate the dynamic behaviour of wind turbines and the wind turbine–grid interaction.

Pscad/Emtdc Based Modeling of a Wind Energy Conversion Scheme for Grid-Connection

The paper presents modeling of a grid-connected wind energy conversion scheme (WECS) with a variable speed drive, a fixed pitch angle, a synchronous generator as a wind generator and an AC-DC-AC conversion scheme for simulating dynamic behaviors and performance simulation responding to varying wind speed input. The electric output of the wind generator is controlled by the AC-DC-AC conversion scheme, the objective of which is to capture the maximum active power under varying wind conditions and to keep the voltage magnitude of the terminal bus at a specific level. Aerodynamic models are applied for a wind turbine model. The modeling and simulation of the WECS are implemented on PSCAD/EMTDC environment.

Embedded Wind Turbine Generation into AC Weak Distribution Grids

A specific wind turbine (WT) generation scheme is used and a control strategy is studied, not only to increase the efficiency of the WT but also to limit the influence on the alternating current (AC) distribution grid. The system is a variable-speed wind-energy conversion scheme, including a synchronous generator with two three-phase stator windings displaced by 30°, which are connected to the AC distribution grid through DC links with Voltage Source Inverters (VSI). A state feedback controller has been designed, using the pole placement technique, to maximize the wind-energy capture. The controller of the DC link secures a smooth supply of the WT electric power to the distribution AC grid by supporting the output voltage and reducing the harmonic distortion. The operation of the proposed system and the efficiency of the control strategy are demonstrated and tested using simulation techniques.

Control design and dynamic performance analysis of a wind turbine-induction generator unit

This paper presents the modeling and control design for a wind energy conversion scheme using induction generators. The scheme consists of a three-phase induction generator driven by a horizontal axis wind turbine and interfaced to the utility through a double overhead transmission line. A static VAr compensator was connected at the induction generator terminals to regulate its voltage. The mechanical power input was controlled using the blade pitch-angle. Both state and output feedback controllers are designed using MATLAB software to regulate the generator output. From the simulation results, the response of closed loop system exhibited a good damping and fast recovery under different type of large disturbances.

Autonomous renewable energy conversion system

This paper briefly reviews the need for renewable power generation and describes a medium-power Autonomous Renewable Energy Conversion System (ARECS), integrating conversion of wind and solar energy sources. The objectives of the paper are to extract maximum power from the proposed wind energy conversion scheme and to transfer this power and the power derived by the photovoltaic system in a high efficiency way to a local isolated load. The wind energy conversion operates at variable shaft speed yielding an improved annual energy production over constant speed systems. An induction generator (IG) has been used because of its reduced cost, robustness, absence of separate DC source for excitation, easier dismounting and maintenance. The maximum energy transfer of the wind energy is assured by a simple and reliable control strategy adjusting the stator frequency of the IG so that the power drawn is equal to the peak power production of the wind turbine at any wind speed. The presented control strategy also provides an optimal efficiency operation of the IG by applying a quadratic dependence between the IG terminal voltage and frequency V∼ f 2. For improving the total system efficiency, high efficiency converters have been designed and implemented. The modular principle of the proposed DC/DC conversion provides the possibility for modifying the system structure depending on different conditions. The configuration of the presented ARECS and the implementation of the proposed control algorithm for optimal power transfer are fully discussed. The stability and dynamic performance as well as the different operation modes of the proposed control and the operation of the converters are illustrated and verified on an experimental prototype.

A variable speed wind energy conversion scheme for connection to weak AC systems

A three level control system for a variable speed wind energy conversion scheme (VSWECS) supplying a weak AC power system is presented. The objective of the control strategy is to maximize energy capture and simultaneously to support the voltage of the bus where the VSWECS is connected. Using an insulated gate bipolar transistor (IGBT) inverter, both control of active and reactive power supplied to the grid and reduction of harmonic distortion can be achieved. The response of the proposed scheme has been tested and evaluated in a test system using a developed computer program simulating in detail the system operation.

A rule-based fuzzy logic controller for a PWM inverter in a stand alone wind energy conversion scheme

The paper presents a rule-based fuzzy logic controller to control the output power of a pulse width modulated (PWM) inverter used in a stand-alone wind energy conversion scheme (SAWECS). The self-excited induction generator used in SAWECS has the inherent problem of fluctuations in the magnitude and frequency of its terminal voltage with changes in wind velocity and load. To overcome this drawback the variable magnitude, variable frequency voltage at the generator terminals is rectified and the DC power is transferred to the load through a PWM inverter. The objective is to track and extract maximum power from the wind energy system and transfer this power to the local isolated load, This is achieved by using the fuzzy logic controller which regulates the modulation index of the PWM inverter based on the input signals: the power error; and its rate of change. These input signals are fuzzified, that is defined by a set of linguistic labels characterized by their membership functions predefined for each class. Using a set of 49 rules which relate the fuzzified input signals to the fuzzy controller output, fuzzy set theory and associated fuzzy logic operations, the fuzzy controller's output is obtained. The fuzzy set describing the controller's output (in terms of linguistic labels) is defuzzified to obtain the actual analog (numerical) output signal which is then used to control the PWM inverter and ensure complete utilization of the available wind energy. The proposed rule-based fuzzy logic controller is simulated and the results are experimentally verified on a scaled down laboratory prototype of the SAWECS.

A utility interactive wind energy conversion scheme with an asynchronous DC link using a supplementary control loop

The paper presents modelling, simulation and experimental verification of a utility interactive wind energy conversion scheme with an asynchronous link comprised of a diode bridge rectifier and a line commutated inverter. The control objective is to track and extract maximum power from the wind energy system and transfer this power to the electric utility. This is achieved by controlling the firing delay angle of the inverter. Since the diode bridge rectifier has no control on the DC link voltage, a supplementary control loop is used to limit the voltage within a preset voltage threshold. The proposed scheme for regulating the flow of power through the DC link ensures reduced reactive power burden on the self-excitation capacitor banks and better utilisation of available wind energy, while limiting the DC link voltage within a preset voltage threshold. The simulated results are experimentally verified and found to give good power tracking performance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wind Energy Conversion Using A Self-Excited Induction Generator

A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated over a wide speed range. Harmonic analysis of the proposed scheme shows that harmonic currents and their associated power loss is negligible.