Exhaustive Comparison between Linear and Nonlinear Approaches for Grid-Side Control of Wind Energy Conversion Systems (original) (raw)
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International Journal of Power Electronics and Drive Systems (IJPEDS), 2021
This article addresses the problem of controlling an overall wind energy conversion system (WECS) formed by a wind turbine connected to the grid via a doubly fed induction generator (DFIG) and an AC/DC/AC converter. The main control objectives are fourfold: (i) designing an output feedback speed controller that makes the DFIG rotate at the optimal value delivered by the MPPT strategy, (ii) controlling the stator reactive power so as to be null, (iii) guaranteeing the DC-link voltage in the grid side converter to be at a given constant value, (iv) ensuring a unitary power factor. A high gain observer is synthesized, in order to provide estimated values of the mechanical variables. To achieve the control objectives, a sliding mode controller involving the mechanical observer is designed. The performance of the system configuration based on the 2MW-DFIG with the proposed controller is evaluated by a numerical simulation under a realistic wind profile using MATLAB/SIMULINK/SimPowerSystems environment. This is an open access article under the CC BY-SA license.
Sliding Mode Power Control of Variable-Speed Wind Energy Conversion Systems
IEEE Transactions on Energy Conversion, 2008
This paper addresses the problem of controlling power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two operation regions depending on wind turbines tip speed ratio. They are distinguished by a minimum phase behavior in one of these regions and a nonminimum phase in the other one. A sliding mode control strategy is then proposed to ensure stability in both operation regions and to impose the ideal feedback control solution despite of model uncertainties. The proposed sliding mode control strategy presents attractive features such as robustness to parametric uncertainties of the turbine and the generator as well as to electric grid disturbances. The proposed sliding mode control approach has been simulated on a 1.5-MW three-blade wind turbine to evaluate its consistency and performance. The next step was the validation using the NREL (National Renewable Energy Laboratory) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures and Turbulence code). Both simulation and validation results show that the proposed control strategy is effective in terms of power regulation. Moreover, the sliding mode approach is arranged so as to produce no chattering in the generated torque that could lead to increased mechanical stress because of strong torque variations.
Entropy
In order to extract efficient power generation, a wind turbine (WT) system requires an accurate maximum power point tracking (MPPT) technique. Therefore, a novel robust variable-step perturb-and-observe (RVS-P&O) algorithm was developed for the machine-side converter (MSC). The control strategy was applied on a WT based permanent-magnet synchronous generator (PMSG) to overcome the downsides of the currently published P&O MPPT methods. Particularly, two main points were involved. Firstly, a systematic step-size selection on the basis of power and speed measurement normalization was proposed; secondly, to obtain acceptable robustness for high and long wind-speed variations, a new correction to calculate the power variation was carried out. The grid-side converter (GSC) was controlled using a second-order sliding mode controller (SOSMC) with an adaptive-gain super-twisting algorithm (STA) to realize the high-quality seamless setting of power injected into the grid, a satisfactory power...
Indonesian Journal of Electrical Engineering and Computer Science, 2021
The wind energy conversion system (WECS) consists of many subsystems, which present control difficulties due to the strong nonlinearities of the models and the effects of internal or external disturbances. In this work, the WECS is based on a doubly feed induction generator (DFIG) directly connected to the stator side network and interconnected via a power converter on the rotor side. The aim of the control strategy is to achieve regular regulation of the powers supplied by the generator and to produce energy of better quality. In order to improve the dynamic behavior of the doubly fed induction generator (DFIG); a comparative study is presented between two advanced control strategies; the second order sliding mode control and the FTSMC fast terminal sliding mode control. The proposed advanced tracking controller is synthesized based on the Lyapunov stability theory and guarantees the existence of the sliding mode around the sliding surface in a finite time. The analysis of the simulation results under the Matlab/Simulink environment confirms the effectiveness of the proposed methods through the performances obtained.
Low-power wind energy conversion system with variable structure control for DC grids
2014 IEEE 5th International Symposium on Power Electronics for Distributed Generation Systems (PEDG), 2014
This paper presents a discussion on the use of variable structure control, i.e., sliding mode control, for improving the dynamic control performance of a low-power wind energy conversion system (WECS) that is connected to a DC microgrid. The sliding mode control is applied to the wind turbine system to extract the maximum possible power from the wind, thus achieving the state of maximum power point tracking to reach the maximum power generation (MPG), and also applied to the power converter to reach the maximum power injection (MPI) to the load. The amount of energy extractable from a dynamically changing wind using the WECS with sliding mode control is compared with that of the classic PI controller. Simulation results show that for a dynamically changing wind, more energy can be harvested with the sliding mode control as compared to the PI control. Index Terms-Wind energy conversion system (WECS), variable structure control (VSC), maximum power generation (MPG), maximum power injection (MPI), maximum power flow.
Electrical Engineering & Electromechanics, 2022
An improved sliding mode control for reduction of harmonic currents in grid system connected with a wind turbine equipped by a doubly-fed induction generator Introduction. The implementation of renewable energy resources into the electrical grid has increased significantly in recent years. Wind power is one of the existing resources. Presently, power electronics has become an indispensable tool in wind power plants. Problem. However the associated control usually has an impact on increasing the harmonic distortion, especially on the output voltage. Goal. This paper proposes a new sliding mode control strategy, applied on a rotor-side of a doubly-fed induction generator. The main goal is to meet the electrical power requirements, while responding to the power quality issues. Methodology. The wind energy conversion system must be able to not only track the maximum power point of the wind energy, but also to mitigate the harmonic currents caused by the non-linear loads. To achieve this goal, the power converters are driven by the proposed sliding mode control strategy. The corresponding two gains of the sliding surface are well selected using a particle swarm optimization algorithm. The particle swarm optimization algorithm solves a constrained optimization problem whose fitness function is a prior formulated as the sum of two mean square error criterions. The first criterion presents the tracking dynamic of the reference active power while the second one presents the tracking dynamic of the reference reactive power. The novelty lies in the implementation of the particle swarm optimization algorithm in conventional sliding mode control strategy, in which the proposed-improved sliding mode control strategy is developed. The wind energy conversion system control uses the principal of the vector oriented control to decouple the control of the active power from that of the reactive power. Results. The improved sliding mode control strategy is applied to control separately theses powers in the presence of non-linear loads. The energy assessment of this strategy is analysed using the wind energy conversion system model based on SimPower software. Originality. The obtained simulation results confirm the superiority of the proposed-improved sliding mode control strategy in terms of reference tracking dynamics and suppression of harmonic currents. References 23, tables 2, figures 11.
Sliding Mode Control Strategy for Wind Turbine Power Maximization
The efficiency of the wind power conversions systems can be greatly improved using an appropriate control algorithm. In this work, a sliding mode control for variable speed wind turbine that incorporates a doubly fed induction generator is described. The electrical system incorporates a wound rotor induction machine with back-to-back three phase power converter bridges between its rotor and the grid. In the presented design the so-called vector control theory is applied, in order to simplify the electrical equations. The proposed control scheme uses stator flux-oriented vector control for the rotor side converter bridge control and grid voltage vector control for the grid side converter bridge control. The stability analysis of the proposed sliding mode controller under disturbances and parameter uncertainties is provided using the Lyapunov stability theory. Finally simulated results show, on the one hand, that the proposed controller provides high-performance dynamic characteristics, and on the other hand, that this scheme is robust with respect to the uncertainties that usually appear in the real systems.
Fuzzy sliding mode power control for wind power generation systems connected to the grid
International Journal of Power Electronics and Drive Systems (IJPEDS), 2021
In recent years we have witnessed a real increase in the production of wind turbines and wind farm installations around the world, in order to improve this own energy, several studies have focused on the interest of controlling the active and reactive power of the system. Wind power, and at the same time on the quality of the energy produced and its connection in order to ingest suitable electrical energy into the distribution network. This article studies a new control technology to meet the various constraints in the field. The objective for work is to develop and study the sliding mode control method applied to a wind power system based on doubly fed induction generation (DFIG), as well as an optimization using the fuzzy logic technique. Ensuring the stability of the system is one of the objectives of using the Lyapunov nonlinear technique in the sliding mode control strategy which will be applied to the two converters (machine side and network side). The proposed solution was to validate a simulation on MATLAB/Simulink, tracking test (true wind speed) and also the robustness of the system.
IEEE Systems Journal, 2012
This paper focuses on the development of a control strategy for integration of wind energy conversion systems (WECS) into the electrical distribution networks with particular attention to the combined provision of energy and ancillary services. Typically, a WECS is composed by a variable speed wind turbine coupled with a direct driven permanent magnet (DDPM) synchronous generator. This configuration offers a considerable flexibility in design and operation of the power unit, as its output is delivered to the grid through a fully controlled frequency converter. Here, a new control scheme to regulate electrical and mechanical quantities of such generation unit is proposed, aimed both at reaching optimal performances in terms of power delivered to the grid and at providing the voltage support ancillary service at the point of common coupling. The control scheme is derived resorting to the feedback linearization (FBL) technique, which allows both decoupling and linearization of a non linear multiple input multiple output system. Several numerical simulations are then performed in order to show how the flexibility of the DDPM wind generator can be fully exploited, thanks to the use of the FBL approach, which assures independent control of each variable and significant simplifications in controller synthesis and system operation, thus making it easier to integrate WECS into modern day smart grids.
High order sliding mode control of active and reactive powers for DFIG based Wind turbine
E3S Web of Conferences
Grid connected wind turbines are considered as a wise alternative to conventional energy sources; not only they are used to produce energy, but they have been recently operated in order to provide grid ancillary services such as stability and frequency control. In this paper we are going to deal with the famous doubly fed induction generator (DFIG) based Wind Energy Conversion Systems (WECS) for its variable speed operation and excellent power quality. The purpose of this study is to apply a High Order Sliding Mode Control (HOSMC) based on vector control and to compare the results with the first order sliding mode control (FOSMC) in order to evaluate the performances of stability and chattering elimination under normal conditions. Simulation results show the superiority of the SOSMC over the FOSMC in terms of robustness and chattering elimination.