Operation Of Wind Energy Conversion System Research Articles

LVRT Enhancement of DFIG-based WECS using SVPWM-based Inverter Control

Abstract: Across many countries, wind turbine generation systems (WTGS) have been established over the past few decades. In this paper, we augment the low voltage ride-through (LVRT) enrichment facility of driving a DFIG-based wind energy conversion system (WECS) using space vector pulse width modulation (SVPWM)-based inverter control. The proposed technique employs an SVPWM-based control algorithm to regulate the voltage and frequency of the output power during grid faults, thereby enhancing the WECS's ability to remain connected to the grid and provide power. The study focuses on decreasing transient current throughout the instant of fault. Modeling and control approaches were also discussed in this study. The performance of the proposed technique is evaluated using MATLAB/Simulink simulations, and the results demonstrate that the technique effectively improves the LVRT capability of the DFIG-based WECS. Background: Due to the variation in wind speed, the power generated by wind turbines is inconsistent. The power generated and the losses in wind turbines change correspondingly with changes in wind speed. The only type of machine that can generate power at speeds below the fixed speed is the doubly-fed induction generator (DFIG). But DFIG is oversensitive to network faults, which makes the bidirectional converters and DC link capacitor fail due to high inrush current and over-voltage. Methods: The converters connected to DFIG consist of an AC-to-DC converter, a boost converter, and a space vector pulse width modulation (SVPWM)-based DC-AC converter. The performance of the SVPWM controller is analyzed during symmetrical and unsymmetrical fault conditions. Results: The anticipated control provides adequate reactive power support to the network through the time of the fault and improves voltage and current waveform. The reactive power flow is also analyzed, and the effectiveness of the proposed controller is verified using MATLAB and Simulink. Conclusion: SVPWM (Space Vector Pulse Width Modulation)-based inverter control is an effective technique for wind energy conversion systems (WECS). The use of SVPWM can provide accurate and precise control of the AC voltage generated from the DC voltage source, resulting in improved system efficiency and reduced harmonic distortion in the output waveform. : The comparative analysis of THD suggests that SVPWM is a superior technique compared to other inverter control techniques such as sine-triangle pulse width modulation (SPWM) and carrier-based pulse width modulation (CPWM). SVPWM can help to reduce the distortion in the output waveform, leading to improved system efficiency, reduced wear on the system components, and overall better performance of the WECS. Furthermore, SVPWM offers several advantages over other inverter control techniques, including better utilization of DC voltage, improved voltage control, and better utilization of switching devices. These advantages make SVPWM a valuable tool for optimizing the operation of WECS and improving the reliability and performance of renewable energy systems. The value of THD for SVPWM inverter control in WECS is 1.53 under symmetrical fault and 1.34 for unsymmetrical fault, respectively. In summary, the use of SVPWM-based inverter control for WECS is an effective way to improve the efficiency and performance of the system while reducing the distortion in the output waveform and providing adequate reactive power support. The advantages of SVPWM over other inverter control techniques make it a valuable tool for the development and optimization of renewable energy systems.

Improvement of power quality in WT-DFIG systems using novel direct power control based on fuzzy logic control under randomness conditions

ABSTRACT In this paper, a novel direct power control technique founded on fuzzy logic controller (FLC-DPC) is selected to master and control the DFIG for wind energy conversion system (WECS). The fuzzy logic controller replaces both hysteresis regulators and the switching table in the proposed strategy. Seeking to enhance the control and overcome the defects associated with the conventional DPC (C-DPC) technique, this control depends on the errors of both active and reactive powers. The suitable rotor voltage vector for the inverter is obtained by FLC-DPC. The proposed control strategy is applied to the WT-DFIG system, in order to study its effectiveness. To reflect a real WECS operation, this study considers the wind’s random behaviour in successive and continuous ways throughout all WT-DFIG operating modes. Also, it takes into consideration all compensated local reactive power modes. The studied system and the proposed control were tested under MATLAB/Simulink environment. The obtained results showed the high effectiveness of the proposed control in terms of response time, robustness and ease. Consequently, C-DPC’s drawbacks are eliminated, and the ripples in compensated local reactive and produced active powers are reduced. Additionally, the total harmonic distortions (THDs) of injected currents are reduced, which improves their quality.

Self-Optimizing Control System to Maximize Power Extraction and Minimize Loads on the Blades of a Wind Turbine

This research proposes a methodology for designing and testing a self-optimizing control (SOC) algorithm applied to a wind energy conversion system (WECS). The SOC maximizes WECS power output and reduces the mechanical stress of the wind turbine (WT) blades by optimizing a multiobjective cost function. The cost function computation uses a combined blade element momentum (BEM) and thin-wall beam (TWB) model for calculating wind the turbine power output and blades’ stress. The SOC deployment implies a low computational cost due to an optimization space reduction via a matrix projection applied to a measurement vector, based on a prior offline calculation of a projection matrix, H. Furthermore, the SOC optimizes the operation of the WECS in the presence of uncertainty associated with the wind speed variation by controlling a linear combination of measured variables to a set point. A MATLAB simulation of a wind turbine model allows us to compare the WECS operating with the SOC, a baseline classic control system (BCS), and a nonlinear model predictive controller (NMPC). The SOC algorithm is evaluated in terms of power output, blades’ stress, and computational cost against the BCS and NMPC. The power output and blades’ stress performance of the SOC algorithm are compared with that of the BCS and NMPC, showing a significant improvement in both cases. The simulation results demonstrate that the proposed SOC can effectively optimize a WECS operation in real time with minimal computational costs.

A novel unified maximum power extraction framework for PMSG based WECS using chaotic particle swarm optimization derivatives

The most important issue in the use of wind energy conversion systems (WECS) is to ensure maximum power extraction for attaining increased efficiency. In this study, maximum power extraction frameworks operating the state-of-the-art optimization methods are presented for permanent magnet synchronous generator (PMSG) based WECS. These frameworks consist of a fast terminal sliding mode control (FTSMC) based MPPT controller and a hybrid MPPT approach that combines chaotic based particle swarm optimization (PSO) derivatives and optimal relation based (ORB) method. Chaotic dynamic weight PSO (CDW-PSO) and Gauss map based chaotic PSO (GM-CPSO), which are remarkable and recent optimization techniques, are utilized to achieve optimum coefficients to ensure efficient MPPT operation. After acquiring the optimum coefficients, the framework passes to ORB operation part. Moreover, the proposed frameworks track extracted power within certain limits during the operation of WECS and make transition between the best coefficients if necessary. On the other hand, FTSMC is used to track the MPPT references that are determined via hybrid MPPT algorithms. To validate the proposed frameworks, they are tested in Matlab/Simulink environment for three specific wind speed scenarios. GM-CPSO based ORB and CDW-PSO based ORB MPPT methods are compared with ORB and tip speed ratio (TSR) methods under these scenarios. Consequently, it is revealed that proposed methods contribute to MPPT efficiency by providing higher power extraction than other conventional methods.

A Concise Presentation of Doubly Fed Induction Generator Wind Energy Conversion Systems Challenges and Solutions

There is increased worldwide wind power generation, a large percentage of which is grid connected. The doubly fed induction generator (DFIG) wind energy conversion system (WECS) has many merits and, as a result, large numbers have been installed to date. The DFIG WECS operation, under both steady state and fault conditions, is of great interest since it impacts on grid performance. This review paper presents a condensed look at the various applied solutions to the challenges of the DFIG WECS including maximum power point tracking, common mode voltages, subsynchronous resonance, losses, modulation, power quality, and faults both internal and from the grid. It also looks at approaches used to meet the increasingly stringent grid codes requirements for the DFIG WECS to not only ride through faults but also provide voltage support. These are aspects of the DFIG WECS that are critical for system operators and prospective investors and can also serve as an introduction for new entrants into this area of study.

Resonant control system for low‐voltage ride‐through in wind energy conversion systems

Owing to the high penetration of electrical energy from wind energy conversion systems (WECSs), some countries are enforcing stringent grid codes to regulate low-voltage-ride-through (LVRT) operation of WECSs. This study presents a self-tuning resonant control (RC) system which can be used for LVRT control of the grid interface in the presence of symmetrical or asymmetrical faults. Only two RCs are required to fully control the four degrees of freedom of the converter output current. Sequence component separation is achieved using a new fast-convergence delayed signal cancellation method which is also discussed in this work. The mathematical analysis and design procedure of the control system are presented. Simulation and experimental results obtained from a 3 kW prototype are discussed in this study.

A proposed strategy for power optimization of a wind energy conversion system connected to the grid

Many strategies have been developed in last decade to optimize power extracted from wind energy conversion system where many of them can produce only 30% more than the rated power. With the considered strategy, the generated wind power can reach twice its nominal value using a fast and reliable fully rugged electrical control. Indeed, by employing a suitable control technique where the produced power in super-synchronous mode is derived from both the stator and the rotor. Also, the rotor provided power in this case grows up 100% comparing to stator rated power. However, this solution permits to maintain the wind energy conversion system operation in its stable area.The considered system consists of a double fed induction generator whose stator is connected directly to the grid and its rotor is supplied by matrix converter. In this paper, the sliding mode approach to achieve active and reactive power control is used. This latter is combined with de Perturbation and Observation Maximum Power Point Tracking used in the second operation zone. The obtained simulations results are assessed and carried out using Matlab/Simulink package and show the performance and the effectiveness of the proposed control.

Artificial Intelligence Based Vector Control of Induction Generator Without Speed Sensor for Use in Wind Energy Conversion System

Indirect field oriented control (IFOC) of squirrel-cage induction generator (SCIG) with full capacity power converter used in wind energy conversion system (WECS) is presented in this paper. In order to improve WECS reliability robust IFOC algorithm using artificial intelligence (AI) for speed estimation was developed. Estimated speed is used for realization of maximum power tracking algorithm (MPPT). Practical testing and validation of considered estimation techniques is performed using advance laboratory prototype of WECS. Extensive experimentation is conducted in order to verify efficiency and reliability of proposed speed-sensorless control technique under realistic WECS operating conditions.

Control of a Self-excited Squirrel Cage Induction Machine based Wind Energy Conversion System Operating in Both Stand Alone and Grid Connected Modes

This paper presents the controller design of a wind energy conversion system built around a self-excited squirrel cage induction machine that can be operated in both standalone and grid connected modes. The control scheme regulates the machine terminal voltage in the standalone mode and the grid side reactive power in the grid connected mode. Both a TCR type SVC and a VSI based STATCOM are employed as flexible reactive power sources. The overall control scheme has been developed and verified in MATLAB/SIMULINK platform. The power versus terminal voltage characteristics, the terminal voltage, system frequency and reactive power versus various load levels in different modes of operation are discussed.

FPGA-based reconfigurable control for switch fault tolerant operation of WECS with DFIG without redundancy

This paper deals with reconfigurable back-to-back converter topology and control orders in Wind Energy Conversion Systems (WECS). A typical WECS with Doubly Fed Induction Generator (DFIG) in balanced conditions is concerned. Based on the classical topology, a fault tolerant converter without any redundancy has been studied. The presented fault tolerant topology allows a “five-leg” structure with converters reconfiguration after switch failure detection. Furthermore, the control strategy for classical topology can no longer be applied after fault occurrence. Thus, a “five-leg” control strategy has also been proposed. The validation of the reconfigurable digital controller for the studied WECS with DFIG topology has been performed using a Hardware-in-the-Loop (HIL) reconfigurable platform including a Field Programmable Gate Array (FPGA) chip. HIL simulation results in both healthy and fault conditions have been presented to show simultaneously the viability of the studied converters topology and the reconfigurable control.

Different Strategies for Controlling Output Power Smoothing of a PMSG-Based Wind Energy Conversion Systems

Abstract This paper deals with controlling the output power smoothing of a wind energy conversion systems (WECS) by using permanent magnet synchronous generator (PMSG). It uses the inertia control of the wind turbine and DC-link voltage control. The PMSG is connected to the grid through a generator-side converter and a grid-side inverter based on AC-DC-AC methods. The generator-side converter is used to control the torque of the PMSG while the grid-side inverter is used to control DC-Link voltage and grid voltage. Fuzzy logic is implemented to determine the torque command by using inertia of wind turbine. The inputs of the fuzzy logic are given by the operating point of the rotational speed of the PMSG and the difference between the wind turbine torque and the generator torque. From the proposed method, the generator torque is smoothed and kinetic energy generated by the inertia of the wind turbine is used to smooth the power fluctuations of PMSG. Also, a stable operation of WECS is achieved during the system fault by using the chopper circuit in the DC-link circuit. The output power smoothing is achieved with stability and low cost. The effectiveness of the proposed method is verified by the numerical simulations.

Unified Power Control for PMSG-Based WECS Operating Under Different Grid Conditions

A unified power control strategy is proposed for the permanent magnet synchronous generator-based wind energy conversion system (WECS) operating under different grid conditions. In the strategy, the generator-side converter is used to control the dc-link voltage and the grid-side converter is responsible for the control of power flow injected into the grid. The generator-side controller has inherent damping capability of the torsional oscillations caused by drive-train characteristics. The grid-side control is utilized to satisfy the active and reactive current (power) requirements defined in the grid codes, and at the same time mitigates the current distortions even with unsymmetrical grid fault. During grid faults, the generator-side converter automatically reduces the generator current to maintain the dc voltage and the resultant generator acceleration is counteracted by pitch regulation. Compared with the conventional strategy, the dc chopper, which is intended to assist the fault ride through of the WECS, can be eliminated if the proposed scheme is employed. Compared with the variable-structured control scheme, the proposed strategy has quicker and more precise power responses, which is beneficial to the grid recovery. The simulation results verify the effectiveness of the proposed strategy.