Wind Generation System Research Articles

Hybrid and adaptive sectors P&O MPPT algorithm based wind generation system

This article suggests a new adaptive perturb and observe (AD-PO) and hybrid P&O (HB-PO) maximum power point tracking (MPPT) algorithms based on the variable speed - wind energy conversion system (WECS) to overcome drawbacks of conventional step-size P&O (CPO) algorithms and to improve the tracking performance of variable step-size P&O (VS-PO) algorithms. Both AD-PO and HB-PO algorithms divide the power-speed (P-ω) curve into modular sectors by estimating the distance between the actual and optimum rotor speed. Furthermore, the limits of operating sectors are continuously modified according to the optimal rotor speed variations. The AD-PO intelligently adapts the perturbation step-size to cope with the rapid wind speed fluctuations, which enables to accurate maximum power point (MPP) tracking. The proposed HB-PO combines the rapid tracking speed and low oscillation levels by specifying number of sectors to operate with VS-PO strategy while remaining sectors to operate with the AD-PO strategy. Moreover, a smart wind speed-sensorless scheme has been established to eliminate the installation of mechanical sensors. Simulation results verify that proposed P&O algorithms offer a 4.0% increase in the WECS efficiency over the conventional algorithm. The effectiveness of proposed control schemes is confirmed by real wind data (Boulder City, Colorado) using MATLAB/SIMULINK environment.

An Adaptive Fuzzy Logic Control Strategy for Performance Enhancement of a Grid-Connected PMSG-Based Wind Turbine

Wind power installations are rapidly increasing worldwide, leading to a huge level of permeation into electricity supply networks. Enormous efforts are spent to improve the performance of the wind turbine generator systems. This paper proposes a novel adaptive fuzzy logic control strategy for performance improvement of a grid-tied wind generator system. The variable-speed wind turbine driven permanent-magnet synchronous generator is tied to the electricity network by a full-capacity power converter. A cascaded adaptive fuzzy logic control strategy is proposed as the control methodology for the generator- and the grid-side converter/inverter. The adaptive technique depends on a continuous mixed $p$ -norm algorithm, which on-line updates the scaling factors of the fuzzy logic controllers (FLCs) at a high convergence speed. For the sake of preciseness, real wind speed data measured in the Zaafarana wind farm, Egypt, are considered in the analyses. The effectiveness of the proposed adaptive FLC is compared to that achieved using particle swarm optimization algorithm based an optimal proportional-integral controller, considering severe grid disturbances. Extensive simulation analyses, which are done using MATLAB/Simulink software, are presented to validate the efficiency of the adaptive fuzzy logic control strategy.

A Dual-Step Integrated Machine Learning Model for 24h-Ahead Wind Energy Generation Prediction Based on Actual Measurement Data and Environmental Factors

Wind power generation output is highly uncertain, since it entirely depends on intermittent environmental factors. This has brought a serious problem to the power industry regarding the management of power grids containing a significant penetration of wind power. Therefore, a highly accurate wind power forecast is very useful for operating these power grids effectively and sustainably. In this study, a new dual-step integrated machine learning (ML) model based on the hybridization of wavelet transform (WT), ant colony optimization algorithm (ACO), and feedforward artificial neural network (FFANN) is devised for a 24 h-ahead wind energy generation forecast. The devised model consists of dual steps. The first step uses environmental factors (weather variables) to estimate wind speed at the installation point of the wind generation system. The second step fits the wind farm actual generation with the actual wind speed observation at the location of the farm. The predicted future speed in the first step is later given to the second step to estimate the future generation of the farm. The devised method achieves significantly acceptable and promising forecast accuracy. The forecast accuracy of the devised method is evaluated through several criteria and compared with other ML based models and persistence based reference models. The daily mean absolute percentage error (MAPE), the normalized mean absolute error (NMAE), and the forecast skill (FS) values achieved by the devised method are 4.67%, 0.82%, and 56.22%, respectively. The devised model outperforms all the evaluated models with respect to various performance criteria.

Adaptive P&O MPPT algorithm based wind generation system using realistic wind fluctuations

In this study, an efficient and fast adaptive perturb and observe (AD-PO) maximum power point tracking (MPPT) algorithm based on the variable - speed wind energy conversion system (WECS) is proposed to eradicate drawbacks of conventional fixed step-size P&O (CPO) algorithms and to enhance the operation of variable step-size P&O (VS-PO). The AD-PO divides the power-speed (P-ω) curve into modular sectors that depend on the estimated wind speed. The step-size is varied adaptively in each sector by observing the distance between the theoretical maximum power point (MPP) and operating power point. The AD-PO enhances the speed convergence with low steady-state oscillations around the MPP. The system configuration involves a 1.5 MW five-phase permanent magnet synchronous generator (PMSG). A back-to-back converter (BTBC) with a dc-link capacitor is used to integrate the PMSG with the utility grid. Simulation results confirm the superiority of the AD-PO over the CPO and the VS-PO MPPT algorithms based on speed convergence and oscillation levels. The performance of the proposed control scheme is validated by real wind data (Boulder City, Colorado) using MATLAB/SIMULINK environment.

New unified NR power flow algorithm for initialising fixed speed wind generation system with turbine characteristics

Fixed speed induction machine-based wind generators are widely used. Proper initialisation of the models representing fixed speed induction machine-based wind generators connected to grid is of primary concern for stability analysis. The initialisation of fixed speed induction generators (FSIG) has been performed using conventional power flow techniques, but there exists a reactive power mismatch which makes initialisation imprecise. Moreover, turbine characteristics along with control mechanisms are not properly included for initialising the dynamics for stability analysis. A unified Newton–Raphson (NR) method was proposed in literature to include turbine characteristics and control methods for accurate initialisation of FSIG. However, this method creates an extra node for every induction machine causing an increase in the size of the Jacobian and time of execution of power flow algorithm. A new unified-NR method, which does not need an extra node, for initialisation of grid-connected FSIG is proposed in the present work. The proposed unified NR method has been validated on 14-bus, 41-bus, 203-bus, and 1336-bus test systems. The results of the proposed new unified-NR method are compared with existing unified-NR method. The results clearly demonstrate that the proposed method initialisation is accurate with considerably less computational time as compared to existing unified-NR.

Robust ${H_\infty }$ Control of Doubly Fed Wind Generator via State-Dependent Riccati Equation Technique

A novel approach on the robust ${H_\infty }$ controller design for the doubly fed induction generator (DFIG)-based wind generation systems through the state-dependent Riccati equation (SDRE) technique is proposed in this paper. The control objective is to mitigate the impact of grid voltage dips to enhance the fault-ride-through capability of the wind generation system. A robust ${H_\infty }$ control problem using the fifth-order detailed DFIG model is formulated to mitigate the impact of voltage dips for the DFIG riding through the faults. The SDRE technique performs extended linearization of nonlinear systems, and the robust ${H_\infty }$ control problem can be solved through an algebraic Riccati equation like approach with state-dependent coefficient (SDC) matrices. The pointwise stabilizability and controllability of the extended linearized system are guaranteed by using the input-to-state stability theory. Accordingly, weighting matrices as well as the SDC matrices are designed with fully studied principles. The notion of controllability Gramian is used to optimize the choice of SDC matrices. The control performance of the proposed robust ${H_\infty }$ controller is verified through case studies. Comparisons with the proportional-integral controllers, the sliding mode control, and the exact linearization-based nonlinear control are performed, which demonstrate better dynamic performances and disturbance attenuation through the proposed controller.

Optimal power extraction control schemes for five-phase PMSG based wind generation systems

This paper presents a variable speed -wind energy conversion system (VS-WECS) based on a large-scale grid-connected five-phase permanent magnet synchronous generator (PMSG). This work studies control techniques for five-phase PMSG, where back-to-back converters (BTBC) are employed on the machine and the grid side converters. Two control loops are employed to control the machine side converter (MSC) in order to attain the optimum power at any wind speed. The outer control loop is applied to adjust the rotor speed while the inner control loop is employed to regulate the generator current. On the other hand, the grid side converter (GSC) employs two control loops; the outer loop controls the DC-link voltage while the inner one regulates the grid current. Moreover, the maximum power point tracking (MPPT) and pitch angle control schemes are utilized to obtain the optimal power during different environmental conditions. The proposed integral sliding mode controller (ISMC) is employed to regulate the rotor speed of the five-phase PMSG to track the reference speed at different wind speed. The proposed ISMC considers the limitations of the conventional PI controller and the dynamic system disturbance, especially in the large wind turbine inertia. Furthermore, the proposed ISMC stability is examined using Lyapunov’s stability function. The performance of the proposed ISMC is compared to a conventional PI controller, the study shows the superior performance of the ISMC. The overall WECS efficiency is improved using the proposed ISMC to 92.45% compared to the PI controller which is 88.12%. The effectiveness of the proposed control scheme is carried out through simulation results using MATLAB/SIMULINK.

Low‐voltage ride‐through enhancement with the ω and T controls of PMSG in a grid‐integrated wind generation system

This study deals with the formulation of a simple control strategy for the enhancement of the low-voltage ride-through (LVRT) capability of the grid-integrated permanent magnet synchronous generator (PMSG)-based wind generation system (WGS). The control warrants satisfying minimum required reactive current support to the ac grid as first priority with minimum loss of generation and maximum utilisation of the converter current capacity during LVRT compliance as per E.ON Netz German grid code requirements. The reference control variables in coordinated control of the stator-side and grid-side converters are altered so as to support the reactive current to the ac grid and, to store the excess active power in the system inertia for keeping the dc-link capacitor voltage in the safe limit during voltage dips at the grid side. The investigations have been made on the proposed strategy of LVRT enhancement with the speed (ω) and torque (T) controls of the direct-drive PMSG in grid-integrated WGS exploiting commonly used tip-speed-ratio and optimum-torque control algorithms of peak power tracking, respectively. Simulation results have been presented to validate the proposed strategy. The performances of the proposed strategy of LVRT enhancement has also been compared to the conventional method like dc-link braking chopper.

Experimental Study on Aerodynamic Characteristics of the Model Wind Rotor System and on Characterization of A Wind Generation System

In order to investigate the aerodynamic characteristics of 6-MW wind turbine, experimental study on the aerodynamic characteristics of the model rotor system and on characterization of a wind generation system is carried out. In the test, a thrust-matched rotor system and a geometry-matched rotor system, which utilize redesigned thrust-matched and original geometry-matched blades, respectively, are applied. The 6-MW wind turbine system is introduced briefly. The proper scaling laws for model tests are established in the paper, which are then implemented in the construction of a model wind turbine with optimally designed blades. And the parameters of the model are provided. The aerodynamic characteristics of the proposed 6-MW wind rotor system are explored by testing a 1:65.3 scale model at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University. Before carrying out the wind rotor system test, the turbulence intensity and spatial uniformity of the wind generation system are tested and results demonstrate that the characterization of the wind generation system is satisfied and the average turbulence intensity of less than 10% within the wind rotor plane is proved in the test. And then, the aerodynamic characteristics of 6-MW wind rotor system are investigated. The response characteristic differences between the thrust-matched rotor system and the geometry-matched rotor system are presented. Results indicate that the aerodynamic characteristics of 6-MW wind rotor with the thrust-matched rotor system are satisfied. The conclusion is that the thrust-matched rotor system can better reflect the characteristics of the prototype wind turbine. A set of model test method is proposed in the work and preparations for further model basin test of the 6-MW SPAR-type floating offshore wind turbine system are made.

Design of a wind turbine generator for rural applications

This paper presents a wind-generation system design for rural applications. In Southern areas of Argentina, there are right conditions for wind energy exploitation. Depending on the characteristics of these areas, the wind-generation systems can operate either isolated or connected to the grid. This work particularly emphasises the design of a generator to optimise the system performance and achieve its minimum volume. The analytical design is evaluated using finite element analysis and experimentally validated using a 35 kW prototype. The tests reveal that the design procedure is suitable. The initially proposed efficiency aim was exceeded, reaching a maximum value of 94.2%. The generator operating conditions make it particularly suited for the application for which it was designed.

Active and reactive power conditioning using SMES devices with PMW-CSC: A feedback nonlinear control approach

Abstract The active and reactive power conditioning using superconducting magnetic energy storage (SMES) systems for low-voltage distribution networks via feedback nonlinear control is proposed in this paper. The SMES system is interconnected to ac grid using a pulsed-width modulated current source converter (PWM-CSC). The dynamical model of the system exhibits a nonlinear structure, which is eliminated by the application of a nonlinear feedback controller based of the expected behavior of the closed-loop system. The steady state analysis under time-domain reference frame to verify the stability properties on the proposed controller is used. The general control rules allow improving different objectives. The robustness and applicability of the proposed controller is tested considering unbalance and harmonic distortion in the voltage provided by the ac grid. It is also considered the possibility to use the SMES system with the proposed controller to compensate the active power oscillations of a wind-generator system.

Optimal Design of Standalone Hybrid Renewable Energy Systems with Biochar Production in Remote Rural Areas: A Case Study

Abstract For remote agriculture-based rural areas, utilizing the local renewable resources such as biomass, wind, and solar energy could be potentially more efficient than long-distance transmission of electricity. In this paper, a multi-objective optimization model for the design of standalone hybrid renewable energy systems (HRES) in remote rural areas is proposed. The objective is to maximize the profits and the carbon abatement capability of the system by optimal process selection and sizing of HRES components including solar, wind, and biomass generation systems. A case study for the design of an HRES on the Carabao Island in the Philippines is conducted. The result shows a 122 kW solar power plant, a 67 kW onshore wind farm and a 223 kW biomass pyrolysis system constitute the optimal configuration of the hybrid energy system, generating a daily profit of US$ 940. The greenhouse gas emission of the optimal system is -3,339 kg CO2 eq/day, indicating good carbon sequestration performance.

A Novel Stability Analysis Approach for the Gird-connected Wind Generator Based on Impedance Ratio Criterion

A novel stability analysis approach is proposed for a gird-connected Wind generator system based on the impedance criterion, which can consider the dynamic characteristics of permanent magnet synchronous generator (PMSG). Firstly, the stability analysis criteria for the grid connected power system with electronic converters is deduced based on the impedance stability analysis principle. Secondly, the small signal model of a PMSG with consideration of the dynamic characteristics of PMSG is established by the state-space equation of PMSG, and the output impedance of a grid-connected PMSG system is derived. On this basis, the stability analysis method for the gird-connected PMSG is obtained. Numerical simulation are performed to validate the proposed control method.

Rapid Prototyping of a Hybrid PV–Wind Generation System Implemented in a Real-Time Digital Simulation Platform and Arduino

The growing penetration of generation systems based on renewable energy in electric power systems is undeniable. These generation systems have many benefits, but also many challenges from the technical point of view. One of the biggest problems in the case of solar photovoltaic (PV) and wind energy is the intermittency of the raw material, thus hybrid generation systems that contain both sources are being used to complement electric power generation. To analyze the problems of this type of hybrid generation systems, it is necessary to develop models and test systems that allows to study their dynamic behavior. Reported in this paper is the implementation of a full hybrid PV–wind generation system model in a real-time digital simulation platform, and the development of the electronic converter controls. These controllers were implemented in digital devices (Arduino Due) and connected to the simulation platform to test their performance in real-time. In addition, the procedure followed for the development and implementation of the controllers is presented. The proposed test system can be used in renewable energy integration studies and the development of new control strategies.

Variable step size P&O MPPT algorithm for optimal power extraction of multi-phase PMSG based wind generation system

To eradicate limitations of conventional fixed step-size perturb and observe (P&O) maximum power point tracking (MPPT) based on the variable speed - wind energy conversion system (VS-WECS), this article proposes a fast and an efficient MPPT modular sectors algorithm. The variable-step perturb and observe (VS-PO) MPPT algorithm is implemented to divide the power-speed (P-ω) curve into modular sectors each with specific step-size. The modular sectors are established by comparing a special synthesized ratio, that associates with the theoretical power, with a specified ratio corresponding the required power accuracy. Hence, the proper step-size is selected according to the operating sector location. For the sectors near the maximum power point (MPP), a small step-size is applied. Otherwise, a large step-size is used. To calculate the theoretical power, a wind speed estimation algorithm is utilized for evaluating the wind speed. The system configuration involves a 1.5 MW five-phase permanent magnet synchronous generator (PMSG), and a back-to-back frequency converter with the dc-link capacitor for the grid integration. The simulation results illustrate the VS-PO superiority over both the conventional P&O (CPO) and modified P&O (MPO) techniques. The VS-PO improves the initial speed tracking and minimizes the steady state oscillations. The performance of the proposed control schemes is validated using MATLAB/SIMULINK environment.

Smoothing control strategy of wind and photovoltaic output power fluctuation by considering the state of health of battery energy storage system

The output power of wind and photovoltaic (PV) systems contain fluctuations due to the intermittent nature of solar irradiance and wind speed. It is required to smooth the fluctuated power before supplying it to the grid. Here, a fuzzy-based discrete Kalman filter approach is proposed for smoothing output power fluctuations of the wind and PV generation systems using a battery energy storage system. The proposed approach incorporates the state of health of the battery as a feedback to not only obtain smooth output power but also improve the battery health by adaptively regulating the battery power. The effectiveness of the proposed approach is verified by evaluating the power fluctuation rates and performance indices.

Frequency Regulation at a Wind Farm Using Time-Varying Inertia and Droop Controls

As renewable power generation becomes more prevalent, the problem of frequency stability has become a particular concern of transmission system operators (TSOs), especially those of small power transmission systems. Traditional wind generation systems do not provide frequency regulation because they are decoupled from the power grid. Therefore, as conventional thermal generators are replaced by wind generators, the issue of frequency regulation for wind generation systems has become increasingly important. To release the kinetic energy stored in the rotating mass, inertia and droop control loops can be added into the controller of a wind turbine (WT). This work proposes an advanced control strategy with the time-varying gains of two control loops. In the proposed strategy, the gains are determined based on the desired frequency-response time. Moreover, the initial gain of the control loop is determined based on the wind speed, considering the operating condition of each WT in a wind farm (WF). The effectiveness of the proposed method is verified using an actual power system, revealing that it can be used to improve frequency regulation in a power grid.

STATCOM Controller Design and Experimental Investigation for Wind Generation System

Controlling of Wind Generation System (WGS) is a vital process to adjust the value of voltage fluctuation that linked to the grid under variations of wind speed. In this paper, a variable speed wind-turbine unit coupled with permanent-magnet synchronous generator is modeled. STATCOM-control methodologies are established on the basis of two controllers; PI controller and Self-Tuning Fuzzy Logic PI-Controller (STFPC). Laboratory model of the WGS using DC motor with an armature current control is designed to achieve a real time simulation of the system. The results are evidenced on the validation of the suggested controlling methodologies. The paper presents experimental comparisons of STFPC with PI-controller. Also, the superiority of utilizing STFPC over PI-controller has been proven.

Harmonic Modeling and Experimental Validation of the Converters of DFIG‐Based Wind Generation System

The double‐fed induction wind generator‐ (DFIG‐) based wind generation system contains power electronic converters and filter capacitor and inductor, which will bring about high‐frequency harmonics under the influence of controllers. Aiming at this problem, this paper studies the relation between the output current and the harmonic source at grid‐side and rotor‐side converters based on their control features in the DFIG system. Furthermore, the harmonic equivalent models of these two converters are built, and the influence of different factors on harmonic features is explored from four perspectives, i.e., modulation method, altering controller parameters, altering output power, and the unbalance of three‐phase voltage. Finally, the effectiveness of the proposed model is verified through the 2 MW DFIG real‐time hardware‐in‐the‐loop test platform by StarSim software and real test data, respectively.

A Fuzzy Logic-based MPPT Technique for PMSG Wind Generation System

Permanent magnet synchronous generator (PMSG)-based wind turbine is considered as one of the promising technologies for generating electric power from wind energy. This paper presents an artificial intelligent technique based on fuzzy logic controller (FLC) to enhance the maximum power point tracking (MPPT) of PMSG-based wind turbine. The FLC method is compared with the conventional methods of MPPT to clarify the superior features of the proposed technique. The comparison between the MPPT methods have been accomplished based on the speed response and new evaluation where the overall system efficiency is considered. A complete model of PMSG with a back to back (BTB) converter along with the control system considering different MPPT techniques is conducted using MATLAB/Simulink O platform. To reveal the robustness and the feasibility of control system, the system is examined under different wind speed profiles. On the basis of the results, good tracking with high accuracy and lower oscillation rate are obtained after using FLC. Moreover, the overall system efficiency is enhanced compared with other MPPT schemes.