Performance Of Wind Energy Conversion System Research Articles

Performance improvement of Grid-Connected Wind Energy Conversion System through Definite Time Horizon Control and MPPT based on Adaptive Observers

This research work investigates the implementation of Definite Time Horizon Control (DTHC) through an observer in a grid-connected Wind Energy Conversion System (WECS) equipped with a Permanent Magnet Synchronous Generator (PMSG). The main objective is to achieve sensorless Maximum Power Point Tracking (MPPT). To achieve this goal, mechanical rotational speed and torque estimates are exploited from an adaptive nonlinear observer. In addition, this work explores how the DTHC improves on the MPPT technique, enabling faster and more accurate tracking of the maximum power point. The proposed controller, unlike traditional non-linear controllers, rapidly stabilizes the WECS, tracking reference trajectories in a short, pre-determined period of time. Indeed, it demonstrates robustness in the face of unpredictable WECS parameters, adapting to variations thanks to a robust control design. Mathematical demonstrations of the defined time horizon stability and the resilience of the suggested WECS controllers are detailed in this investigation. This DTHC method improves rotor speed control, enabling more efficient sensorless MPPT. It contributes to improved WECS performance for following dynamic references and enhances adaptability against unpredictable parameters. In addition, it provides sophisticated control capabilities for the grid connected converter, improving the smoothness and efficiency of electrical energy injection.

A novel MPPT design for a wind energy conversion system using grey wolf optimization

A significant problem is enhancing the reliability of the wind energy conversion system (WECS), when that runs in unpredictable weather. Therefore, it is essential to construct a maximum power point tracker (MPPT), a controller for measuring the optimum power that the WECS is expected to generate. Hill climbing-based techniques were used to simulate the tracker, but they had drawbacks in terms of tracking efficiency and speed. The Grey Wolf optimization algorithm (GWO) for modelling MPPT integrated with the WECS is proposed in this work as a novel, effective method. The system is made up of a wind turbine (WT) conjoined to a permanent magnet synchronous generator (PMSG), a 3-phase rectifier that converts the generator’s AC output power to direct current (DC), and a boost converter whose input DC voltage is controlled by the MOSFET duty cycle. The goal of the modelling procedure is the system’s electrical output power, which is presented as an optimization problem. The results confirmed the GWO-reliability MPPT’s in reaching the desired WECS performance.

Performance Evaluation of Grid-Connected DFIG-Based WECS with Battery Energy Storage System under Wind Alterations Using FOPID Controller for RSC

In the present energy scenario, wind energy is the fastest-growing renewable energy resource on the globe. However, wind-energy-based generation systems are also associated with increasing demands for power quality and active power control in the power network. With the advancements in power-electronics-based technology and its use in non-conventional energy conversion systems, it has witnessed tremendous growth in wind energy conversion systems (WECSs). At the same time, integrating wind farms into the grid system also results in many power quality issues in the power system that involve these renewable energy sources feeding power networks. This paper reports the effectiveness of grid-connected doubly fed induction generator (DFIG)-based WECS with a battery energy storage system (BESS) under variable wind conditions. In this study, a rotor side converter (RSC) is controlled to achieve the optimal torque for a given maximal wind power. The control scheme is simulated using MATLAB for a 2 MW-rated DFIG used in a WECS. Additionally, in this paper, a new fraction order proportional integral derivative (FOPID) controller is introduced into the system’s RSC, and its performance is also observed. The BESS technique is used with a DC link to improve the overall performance of the DFIG-based WECS under different wind conditions. To control the BESS, a proportional integral (PI) controller is introduced to increase the charging and discharging rates. Two models are developed in MATLAB/Simulink: one model is a basic model, and other model is equipped with a BESS and a PI controller in the BESS. The results validate the effectiveness of the proposed PI-controller-equipped BESS at improving the overall performance of the WECS system under study.

Stability and Dynamic Analysis of the PMSG-Based WECS With Torsional Oscillation and Power Oscillation Damping Capabilities

The direct-drive permanent-magnet synchronous generator (PMSG) based wind energy conversion system (WECS) with a soft drivetrain shaft is vulnerable to torsional oscillation when it participates in power oscillation damping (POD) services for the AC grid. This paper investigates three possible scenarios of incorporating both torsional oscillation damping (TOD) and POD controllers into PMSG-based WECS. A model of a PMSG-based offshore wind farm (OWF) connected to the IEEE 39-bus AC grid is developed and utilized to analyze the stability and dynamic performances of the WECS within these three scenarios. Comprehensive modal analysis is carried out to analyze the interaction between the torsional and power oscillations, and to tune the TOD and POD controllers to damp these oscillations simultaneously in each scenario. Furthermore, the dynamic performances of the PMSG-based WECS within these scenarios are evaluated through time-domain simulations. Then an optimal scenario for PMSG-based WECS to damp both oscillation types with close frequencies is identified, which is modulating the DC-link voltage for the TOD and the grid-side active power for the POD. This result can provide useful guidance for the future industrial application of the TOD and POD control in the PMSG-based WECS.

Artificial Intelligence Based Control Strategy of a Three- Phase Neutral-Point Clamped Back-to-Back Power Converter with Ensured Power Quality for WECS

This paper provides an in-depth investigation into the state-of-the-art power converter control approaches utilizing artificial intelligence that ensure the power quality for wind energy conversion systems (WECS). The most promising and feasible wind energy conversion configuration has been elected to be evaluated in an attempt to reduce the computing cost and time, as well as meet the grid code requirements. For this purpose, in this work, a back-to-back neutral-point clamped power converter is controlled with high precision using a machine learning algorithm. The machine is trained offline by data acquired from the well-known voltage-oriented control (VOC) technique. The majority of the computational load is moved from online to offline mode. Thus, there is no need for accurate development of the PI controller parameters and bandwidth, and hence, the cost and time of calculation will be considerably reduced. As a consequence, the recommended machine learning-based technique can take over the conventional VOC responsibilities. To accomplish this, the training dataset is applied to learn the behavior of the system using a locally weighted lasso regression approach. The cost function is then minimized using stochastic gradient descent, batch gradient descent, Broyden–Fletcher–Goldfarb–Shanno (BFGS), and limited-memory BFGS optimizers, successively. The comparative analysis reveals that the BFGS family of optimizers outperforms the counterparts in terms of computation time, accuracy, and THD performance of WECS.

Enhancement of wind energy conversion system performance using adaptive fractional order PI blade angle controller

Wind energy is considered as one of the rapidest rising renewable energy systems. Thus, in this paper the wind energy performance is enhanced through using a new adaptive fractional order PI (AFOPI) blade angle controller. The AFOPI controller is based on the fractional calculus that assigns both the integrator order and the fractional gain. The initialization of the controller parameters and the integrator order are optimized using the Harmony search algorithm (HSA) hybrid Equilibrium optimization algorithm (EO). Then, the controller gains (Kp,Ki) are auto-tuned. The validation of the new proposed controller is carried out through comparison with the traditional PID and the Adaptive PI controllers under normal and fault conditions. The fractional adaptive PI improved the wind turbine's electrical and mechanical behaviors. The adaptive fractional order PI controller has been subjected to other high variation wind speed profiles to prove its robustness. The controller showed robustness to the variations in wind speed profile and the nonlinearity of the system. Also, the proposed controller (AFOPI) assured continuous wind power generation under these sharp variations. Moreover, the active power statistical analysis of the AFOPI showed increase in energy captured of around 25 %, and reduction in the standard deviation and root mean square error of around 10% compared to the other controllers.

Robust Adaptive HCS MPPT Algorithm-Based Wind Generation System Using Model Reference Adaptive Control.

To treat the stochastic wind nature, it is required to attain all available power from the wind energy conversion system (WECS). Therefore, several maximum power point tracking (MPPT) techniques are utilized. Among them, hill-climbing search (HCS) techniques are widely implemented owing to their various features. Regarding current HCS techniques, the rotor speed is mainly perturbed using predefined constants or objective functions, which makes the selection of step sizes a multifaceted task. These limitations are directly reflected in the overall dynamic WECS performance such as tracking speed, power fluctuations, and system efficiency. To deal with the challenges of the existing HCS techniques, this paper proposes a new adaptive HCS (AD-HCS) technique with self-adjustable step size using model reference adaptive control (MRAC) based on the PID controller. Firstly, the mechanical power fluctuations are detected, then the MRAC continuously optimizes the PID gains so as to generate an appropriate dynamic step size until harvesting the maximum power point (MPP) under the optimal tracking conditions. Looking specifically at the simulation results, the proposed AD-HCS technique exhibits low oscillations around the MPP and a small settling time. Moreover, WECS efficiency is increased by 5% and 2% compared to the conventional and recent HCS techniques, respectively. Finally, the studied system is confirmed over a 1.5 MW, gird-tied, double-fed induction generator (DFIG) WECS using MATLAB/Simulink.

Comparison Of Three Numerical Methods For Estimating Weibull Parameters Using Weibull Distribution Model In Nigeria

There is a crucial need in Nigeria to enhance the development of wind technology in order to boost our energy supply. Adequate knowledge about the wind speed distribution becomes very essential in the establishment of Wind Energy Conversion Systems (WECS). Weibull Probability Density Function (PDF) with two parameters is widely accepted and is commonly used for modelling, characterizing and predicting wind resource and wind power, as well as assessing optimum performance of WECS. Therefore, it is paramount to precisely estimate the scale and shape parameters for all regions or sites of interest. Here, wind data from year 2000 to 2010 for four different locations (Port Harcourt, Ikeja, Kano and Jos) were analysed and the Weibull parameters was determined. The three methods employed are Mean Standard Deviation Method (MSDM), Energy Pattern Factor Method (EPFM) and Method of Moments (MOM) for estimating Weibull parameters. The method that gave the most accurate estimation of the wind speed was MSDM method, while Energy Pattern Factor Method (EPFM) is the most reliable and consistent method for estimating probability density function of wind.
 Keywords: Weibull Distribution, Method of Moment, Mean Standard Deviation Method, Energy Pattern Method

Enhancing the performance of wind energy conversion systems using unified power flow controller

Due to the low converters rating and cost of doubly fed induction generator (DFIG) along with its ability to function under variable wind speed, DFIG has been widely employed in wind energy conversion systems (WECSs). Unfortunately, the performance of DFIG is sensitive to the variation in the operating conditions and disturbance events at the grid side. This includes wind gust, voltage fluctuation and faults at the point of common coupling of the DFIG and the grid. In this study, a model-free adaptive control (MFAC) is developed for a unified power flow controller (UPFC) in order to improve the overall dynamic performance of a DFIG-based WECS during wind gusts and enhance the fault ride through capability of the DFIG during various disturbance events. The effective performance of the proposed controller is assessed through a comparison with a conventional proportional–integral (PI) controller optimised by a modified flower pollination algorithm. Results reveal the superiority of the proposed UPFC-MFAC technique over the conventional PI controller currently used in most of the UPFC-WECS applications.

Mitigating Power Fluctuations for Energy Storage in Wind Energy Conversion System Using Supercapacitors

The world is rapidly shifting to green power resources due to inevitable growing energy needs and increasing environmental concerns. However, the irregular production capacity of renewable energy resources requires additional components in the system for conditioning power quality and to make them a sustainable solution. It imperatively needs an energy storage system, which is crucial for the wind energy conversion system (WECS) to maintain a smooth power supply to loads. However, voltage fluctuations from the wind turbine generator, which are caused by the turbulent nature of wind speed, pose disruptions to the DC charge controller of a battery, and affects battery life. To deal with power fluctuations of the wind turbine generator, this study proposes a WECS that integrates a supercapacitor before the stages of the DC charge controller and the energy storage device. Given that batteries have transient charging and discharging characteristics, a test bench is developed to analyze their patterns during the charging/discharging cycles. The DC charge controller in the proposed WECS is designed to operate in the constant current mode as well as constant voltage mode depending on the state of charge of the battery. The simulations and experiments associated with the performance of WECS with a hybrid energy storage system and conventional system are carried out and presented to substantiate the assertion. To validate the proposed idea, the performance of the WECS and improvement in battery life are examined through the charging pattern of battery before and after the integration of a supercapacitor. The behavior of wind turbine generator variables due to the integration of supercapacitor in WECS is analyzed and discussed in detail. A prototype of WECS combined with an arrangement of a supercapacitor (500 F, 2.7 Vdc) module is built and tested. The simulation and experimental results indicating the impact of the integration of supercapacitor in WECS are presented.

Direct controls for wind turbine with PMSG used on the real wind profile of Essaouira-Morocco city

<span>This article presents the use of a permanent magnet synchronous generator (PMSG) for the wind energy production and electrical energy injection produced into an electrical grid. The objective is to perform modeling and direct control of the Wind Energy conversion System (WECS), taking into account the problems of wind speed variations and generator maintenance. The direct torque control (DTC) is applied to the machine-side converter and direct power control (DPC) is applied to the grid-side converter. The performance of WECS is tested in MATLAB / SIMULINK environment simulation with a real wind profile of Essaouira-Morroco city. The simulation results obtained show that the proposed direct controls provide high performance in terms of setpoint tracking, speed, stability and power quality.</span>

Study of robust adaptive step‐sizes P&O MPPT algorithm for high‐inertia WT with direct‐driven multiphase PMSG

In this study, an efficient robust adaptive perturb and observe (RA-PO) maximum power point tracking (MPPT) algorithm–based wind energy conversion system (WECS) is suggested to avoid drawbacks of conventional P&O (CPO) algorithms. It depends on observing the distance between the actual and optimal rotor speed, calculating the required adaptive ratio at each operating point, perturbing the rotor speed with an appropriate step-size, and observing power variations until the P-ω curve slope equals zero. Therefore, it exhibits a rapid speed tracking with low oscillations. Moreover, it offers a well-defined relationship among the extracted mechanical power, the rotor speed, the perturbing step-size, and the operating wind speed so wrong direction and loss of tracking problems can be avoided on high-inertia wind turbine (WT) during rapid wind speed fluctuations. It improves the WECS efficiency from 87% to 91%. The performance of WECS is confirmed via MATLAB/SIMULINK.

Application of Superconductors to Improve the Performance of DFIG-Based WECS

This paper presents a new cost-effective technique to improve the performance of doubly fed induction generator (DFIG)-based wind energy conversion systems (WECS) during wind gust and fault events through the integration of high temperature superconductor (SC) within the DC link of the rotor side and grid side converters that interface the DFIG rotor with the grid. Fractional order proportional integral (FOPI) controller is employed to control the energy exchange between the SC and the system through controlling the duty cycle of the DC chopper interfacing the SC with the DC link. Rating of the SC and parameters of the proposed FOPI controller are precisely calculated using harmony search optimization technique in order to regulate the DFIG generated power and improve its fault ride through capability during disturbance events. To validate the superiority of the proposed FOPI controller, the performance of the studied system is also investigated when a conventional PI controller is employed. Results reveal the ability of the proposed topology and controller to improve the performance of the DFIG-based WECS during wind gust and short circuit faults at the DFIG terminals.

Particle Swarm Optimization based Fuzzy Logic MPPT Inverter Controller for Grid Connected Wind Turbine

The wind energy sources as an alternative to conventional sources to generate power has been increasingly popular due to abundant in nature and pollution free. The wind energy sources are undepletable, however, they are not able to generate as much electricity due to their intermittent nature. Therefore, a wind energy conversion system (WECS) with accurate maximum power point tracking (MPPT) inverter controller is essential in order to improve the wind energy capturing capability. This paper aims to develop an optimal Fuzzy logic MPPT inverter controller for grid connected wind turbine so that the energy capturing efficiency of the system can be maximized. In this research work, the MPPT inverter controller is designed on the basis of fuzzy logic control and heuristic particle swarm optimization (PSO) algorithm. The performance of WECS are demonstrated with the generated output voltage, current and power waveforms, the rectifier current waveform, DC link voltage waveform, and the generator speed. According to the results obtained for both normal Fuzzy logic MPPT control and optimized Fuzzy logic MPPT control WECS, the performance of PSO optimized Fuzzy logic MPPT inverter controller has better maximum power point performance and efficiency in tracking wind energy in terms of much smooth, less distortion and fewer fluctuation outcomes at the various step wind speed conditions. The proposed optimal Fuzzy logic MPPT inverter controller has a good potentiality for WECS in sustainable grid application.

ENGLISH

3 ABSTRACT: In modern wind turbines, the energy conversion process uses the basic aerodynamic force of lift to produce a net positive torque on a rotating shaft, resulting first in the production of mechanical power and then its conversion to electricity in a generator. Wind turbines, unlike most other turbines, can produce power only in response to the wind that is available at the time. The output of a wind turbine is thus inherently fluctuating with the wind and can't be directly dispatched for a purpose. Apart from this, the output depends on individual components like rotor dimension, transmission shaft, gear box and alternator. Since the wind turbine is relatively large, expensive, and Wind Energy Conversion System (WECS) is complex, it is not convenient to do research on actual wind farm. Therefore, WECS model development for steady and dynamic state analysis and design has been research issue in recent years. This paper presents a new block-based approach for WECS dynamic modeling. The blocks (modules) developed by Aalborg University - Denmark, RISO national laboratory based on Kaimal Spectra have been customized, updated and integrated into MATLAB/SIMULINK platform and then utilized to simulate performance of 5kW WECS. In addition to the developed block sets, in this paper, a proportional-integral controller is designed to control the turbine pitch and integrated with the simulation models. The simulation result demonstrates that the model output is in agreement with what is expected. The system has advantages like: research cost reduction, ease in application and control, flexibility and completeness for analysis in MATLAB/SIMULINK environment. The system can be used for assessment of power quality and design of wind turbine system for grid connection.

Cogeneration topology for wind energy conversion system using doubly‐fed induction generator

A novel wind energy conversion system (WECS) with cogeneration topology is presented in this study. In the proposed scheme, doubly-fed induction generator (DFIG) is used as the major source for power generation in grid-isolated mode. The wind turbine operated DFIG is integrated with a permanent magnet ac generator and a solar photovoltaic (PV) module to supplement the both rotor power requirement of DFIG and part of the average load power demand. The performance of a grid-isolated WECS, over wide speed range can be significantly improved through the sequential extraction of wind power along with an augmented solar PV source. The proposed scheme is economically viable with feasible unit cost of generated power. The control scheme has been simulated and experimentally validated with a practical 2.5 kW DFIG using dSPACE DS1104 module, which produced satisfactory results.

Maximum Likelihood Output Curve and Modal Bounds for Active Pitch-Regulated Wind Turbine

A scatter of operating points is commonly observed over time whenever a pitch angle controlled (PAC) wind energy conversion system (WECS) operates in source wind susceptible to short duration variations caused by turbulence and gusts. A suitable interpretation of the distributed operating points can be useful in the context of real-time performance of WECS, and its evaluation once integrated within a conventional power network. This paper provides conceptual background culminating in an algorithm that allows estimation of most probable ( maximum likelihood ) operating points for a pitch angle-controlled WECS. It further allows establishment of modal bounds , within which short duration operating points are expected to occur given a modal cumulative probability . The concepts and algorithm are illustrated for a popular make of WECS assumed to operate in source wind conditions according to IEC61400-1 standards. Following from the concepts proposed, indications are provided for possible refinement of WECS output power curves thereby aiming to achieve better short duration unit performance.

On the rejection of internal and external disturbances in a wind energy conversion system with direct-driven PMSG

This paper deals with the critical issue in a wind energy conversion system (WECS) based on a direct-driven permanent magnet synchronous generator (PMSG): the rejection of lumped disturbance, including the system uncertainties in the internal dynamics and unknown external forces. To simultaneously track the motor speed in real time and capture the maximum power, a maximum power point tracking strategy is proposed based on active disturbance rejection control (ADRC) theory. In real application, system inertia, drive torque and some other parameters change in a wide range with the variations of disturbances and wind speeds, which substantially degrade the performance of WECS. The ADRC design must incorporate the available model information into an extended state observer (ESO) to compensate the lumped disturbance efficiently. Based on this principle, a model-compensation ADRC is proposed in this paper. Simulation study is conducted to evaluate the performance of the proposed control strategy. It is shown that the effect of lumped disturbance is compensated in a more effective way compared with the traditional ADRC approach.

Optimum design of proportional-integral controllers in grid-integrated PMSG-based wind energy conversion system

Summary In this paper, a direct-driven small permanent magnet synchronous generator (PMSG) wind energy conversion system (WECS) with a back-to-back power converter working in grid-connected mode is discussed. Control structures based on field-oriented control and voltage-oriented control mechanisms are proposed for machine-side converter and grid-side converter, respectively. Optimization approaches namely ‘modulus optimum’ and ‘symmetric optimum’ are used to obtain analytical expressions for the selection of the parameters of involved proportional-integral (PI) controllers in different control loops. A transient system simulation using SimPowerSystem is built to evaluate the performance of the PMSG-based WECS by employing selected values of PI controller parameters both under varying wind conditions and under symmetrical and asymmetrical grid-fault conditions. Copyright © 2015 John Wiley & Sons, Ltd.

A Control Strategy for Power Regulation in a Direct-Drive WECS With Flexible Drive-Train

The ever-increasing penetration of wind power into the electric power systems indicates the need that wind energy conversion systems (WECSs) should be able to regulate their output real power, since their participation in power-flow control is expected to be essential for power systems stability. On the other hand, the tendency to build larger WECSs at competitive costs encourages lighter and, consequently, more flexible drive-trains. However, a softer drive-train may give rise to undamped drive-train oscillations when the WECS exercises output power regulation. This paper proposes an enhanced control strategy that enables a direct-drive WECS based on the permanent magnet synchronous generator (PMSG) to damp its drive-train torsional mode, even if the output real power of the WECS is regulated. A procedure is presented for tuning of the proposed control to ensure the internal stability of the WECS, considering the impacts of the proposed control on the dynamic performance of the host WECS.