Induction Generator-based Wind Energy Conversion Research Articles

Comparative study of controllers in battery energy storage system integrated with doubly fed induction generator-based wind energy conversion system for power quality improvement

This study presents a comparative analysis of controllers in a Battery Energy Storage System (BESS) integrated with a Doubly Fed Induction Generator (DFIG)-based Wind Energy Conversion System (WECS) aimed at improving power quality. The research background introduces the challenges associated with integrating renewable energy sources into the grid, emphasizing the intermittent nature of wind energy and its impact on power quality. Existing detailed problems, including voltage and frequency fluctuations, and grid instability, are outlined, highlighting the need for effective control strategies to mitigate these issues. The paper's contribution lies in evaluating and comparing different control techniques for BESS integration, including Proportional-Integral (PI) control, Fuzzy Logic (FL), and Artificial Neural Network (ANN) control. Through simulation studies conducted in MATLAB/Simulink, the effectiveness of each controller in regulating rotor current, rotor and stator power, voltage stability, state of charge (SoC) and grid synchronization is assessed. The findings provide valuable insights into the optimal controller selection for enhancing power quality in DFIG-based WECS with integrated energy storage systems, contributing to the advancement of renewable energy integration and grid stability.

Analysis of the effect of parametric uncertainty on dynamic performances of doubly fed induction generator-based wind energy conversion system

The wind, stochastic in nature, is one of the fastest-growing and most promising renewable energy resources in the entire world. Thus, this paper investigates the influence of parameter uncertainties upon a dynamic performance of a grid-tied Doubly-Fed Induction Generator (DFIG)-based Wind Energy Conversion System (WECS). The main uncertain parameters found in the study are mutual and rotor winding reactances which occurred due to the variation of the angular positions of the rotor caused by varying wind speeds. The variation in the wind speed caused the generator rotor speed to deviate between 25% and 150%. Consequently, the rotor winding reactance of DFIG changes from its nominal value of 1.31 mΩ to between 0.983 and −0.655 mΩ; and the mutual reactance from its nominal value of 0.941 Ω to between 0.758 and −0.4708 Ω. As a result, the stator and rotor winding voltages and currents of the DFIG are uncertain.

Evaluation of super-twisting SMC and NSC combination for power control in multi-source renewable power generation system

This work is based on the evaluation of a super-twisting sliding mode controller for power control in an isolated multi-source renewable generation system. The hybrid multi-source system taken into consideration, in this case, is made up of three different generation units. The main generation unit is a 22kW micro-hydro system with a self-excited induction generator. To this, a 7.5kW doubly fed induction generator-based wind energy conversion system is integrated. An 18kW solar PV system connected to a battery energy storage system is connected at the dc-link. All the above systems are integrated through a bidirectional nine-switch converter. The autonomous hybrid system's power control is solely done by the nine-switch converter. In this work, efforts have been made to combine the robustness and accuracy of super-twisting sliding mode controllers with the reliability and flexibility of the nine-switch converters. The performance evaluation of the above combination is done with various load and source side disturbances. The system's uninterrupted power supply capability has also been examined in this work. Using the MATLAB environment, the system's performance is evaluated, examined, and the same has been verified using an OPAL-RT 4510 real-time simulator.

A grid forming control for wind energy conversion systems

This paper presents an effective and practical structure to improve voltage and frequency regulation in grid-forming control of self-excited induction generator-based wind energy conversion systems. In the proposed control structure, in addition to a fixed parallel excitation capacitor, a small wound rotor synchronous generator is also used as a reactive power compensator. The excitation voltage of the small synchronous generator is controlled in such a way that by injecting the required amount of reactive power, this generator maintains the balance between the inductive and the capacitive reactive powers in the isolated system, and thus, improves the system voltage regulation. In addition, an active power control is proposed in which the speed of the prime mover of the self-excited squirrel cage induction generator is adjusted in such a way that the active power of the small synchronous generator is maintained at zero value. The proposed power controller, by creating the balance between the generated and the consumed active powers, improves the frequency regulation of the wind energy conversion system. The validity and effectiveness of the proposed structure are demonstrated through both simulation studies and experimental implementation. The obtained results confirm that the poor regulation of voltage and frequency, which is one of the major drawbacks of self-excited induction generator-based wind energy conversion systems, has been significantly mitigated by using the proposed method.

Evaluating the performances of PI controller (2DOF) under linear and nonlinear operations of DFIG-based WECS: A simulation study

Owing to different stochastic characteristics of wind energy systems, there would commonly be uncertainties in the processes of wind energy conversion that may ultimately cause to severely degrade the quality of electric power production. These uncertainties include time-varying fluctuations of mechanical & electrical parameters that can be generated during both linear, and nonlinear operating behaviors of doubly fed induction generator-based wind energy conversion system (DFIG WECS). In order to handle a wind power quality problem, the previous studies largely focused on adjustment of mechanical parameters particularly based on blade pitch angle control by proposing different control strategies, and controller models. This work proposes a rarely studied electrical parameter control method that is particularly used to implement the regulation of rotor current components & electromagnetic torque in a DFIG WECS, based on Indirect Field Oriented Control (IFOC) strategy. Accordingly, a novel Proportional Integral controller model that employs a 2-Degree-of-Freedom [PI (2DOF)] is illustrated for an enhanced control of the rotor current components (quadrature & direct currents), electromagnetic torque under a 2MW DFIG WECS, which is operationally assumed to behave both linearly & nonlinearly. Herein, nonlinear operating behavior signifies a voltage dip that was assumed to be resulting when the system's normal (linear) voltage would suddenly drop by 90%. Furthermore, the overall model of the DFIG system was simulated in MATLAB-SIMULINK environment to evaluate the performances of PI controller (2DOF) under the system's stated operating behaviors. Based on the simulation signal statistics, the quadrature current distortion levels & DC mean values were mainly considered as the criteria for evaluating the controller performances. Finally, the proposed PI controller (2DOF) model has been tested to achieve an enhanced power quality in comparison with the traditional PI controller model.

Fault Ride-Through Operation Analysis of Doubly Fed Induction Generator-Based Wind Energy Conversion Systems: A Comparative Review

In present electrical power systems, wind energy conversion systems based on doubly fed induction generators represent one of the most commonly accepted systems in the global market due to their excellent performance under different power system operations. The high wind energy penetration rate makes it challenging for these wind turbines to follow grid code requirements. All operations of a wind energy system during a dip in voltage require special attention; these operations are critically known as fault ride-through and low voltage ride-through. In this paper, various fault ride-through techniques of doubly fed induction generator-based wind energy conversion systems, such as protective circuitry, reactive power injection, and control methods for transient and steady state operations, have been presented to improve the performance. During system disturbances, protective circuitry or control mechanisms are typically used to limit the over-current of the rotor and the generated inappropriate DC link over-voltage. Simultaneously, the reactive power injection system overcomes the reactive power scarcity and enhances the transient response, further limiting the DC bus voltage and rotor current. This review paper compares and suggests appropriate FRT methods that are driven by external modifications and internal system improvements. Furthermore, typical case studies are discussed to illustrate and support the FRT system. The impact of each case study was evaluated and analyzed using the results obtained from the MATLAB/Simulink application and the OPAL-RT (OP4500) real time simulator (RTS).

Analysis of Dual Stator Winding Induction Generator-Based Wind Energy Conversion System Using Artificial Neural Network Maximum Power Point Tracking

Analysis of Dual Stator Winding Induction Generator-Based Wind Energy Conversion System Using Artificial Neural Network Maximum Power Point Tracking

Enhancing the Fault Ride-through Capability of a DFIG-WECS Using a High-Temperature Superconducting Coil

With the increase in doubly fed induction generator-based wind energy conversion systems (DFIG-WECS) worldwide, improving the fault ride-through (FRT) capability of the entire system has been given much attention. Enhancement of the FRT capability of a DFIG-WECS is conventionally realized by employing a flexible AC transmission system device with a proper control system. This paper presents a non-conventional method for the improvement of the FRT of DFIG-WECS, using a high-temperature superconducting coil interfaced with the DC-link of the rotor and stator side converters through a DC-chopper. A fractional-order proportional-integral (FOPI) controller is utilized to regulate the DC-chopper duty cycle in order to properly manage the power flow between the DC-link and the coil. Two optimization techniques, Harmony Search and Grey Wolf Optimizer, are employed to determine the optimum size of the superconducting coil along with the optimum parameters of the FOPI controller. The effectiveness of the two proposed optimization techniques is highlighted through comparing their performance with the well-known particle swarm optimization technique.

Optimal Tuning of a New Multi-input Multi-output Fuzzy Controller for Doubly Fed Induction Generator-Based Wind Energy Conversion System

Optimal Tuning of a New Multi-input Multi-output Fuzzy Controller for Doubly Fed Induction Generator-Based Wind Energy Conversion System

A Robust Control for SCIG-Based Wind Energy Conversion Systems Based on Nonlinear Control Methods

This paper presents a nonlinear control structure for variable-speed squirrel cage induction generator-based wind energy conversion systems. The proposed control structure consists of two control systems designed for machine side converter (MSC) and grid side converter (GSC). The MSC controller is based on adaptive input–output feedback linearization designed in a new reference frame and is responsible for controlling the flux and torque of the machine. Torque control is achieved through a PI controller that its output determines the speed of the presented reference frame at each moment. For the GSC, a sliding mode-based control system is designed to control the DC link voltage in addition to controlling the active and reactive power exchanged with the grid. The validity and effectiveness of the proposed control structure have been investigated through simulation studies in MATLAB® software environment.

Diagnosis of Fault in Doubly-Fed Three-Phase Induction Generator in Wind Power Applications

Inter-turn short-circuits faults are one of the most common problems in Induction machines, especially in the Doubly-Fed Induction Generator Based-Wind Energy Conversion system. Accurate and fast fault diagnosis and detection minimize the down-time of the units as further damages can be prevented. In this paper, a robust fault detection approach for Doubly-Fed Induction Generator (DFIG) based on wind generators is proposed. The faults’ smart diagnosis and detection are based on the Sliding Mode Observer and Second Order Sliding Mode Control. The observer generates a residual for detection of stator Inter-Turn Short Circuit faults which can affect a system model. A decision system is used to process the residual vector to detect faults. In order to shed more light on the designed approach performances regarding the inter-turn short-circuit fault occurrence, simulations were implemented in MATLAB/Simulink environment.

Enhancement of Low Voltage Ride Through Capability of Doubly Fed Induction Generator Based Wind Turbine Using Fuzzy Logic Controller

Combined impact of environmental issues and policies of utilities has led to generation of clean and sustainable energy. Solar and wind energies are prominent and can provide bulk amount of electrical energy. Vast number of resources and more electrical energy density are attractive features of wind energy. Generation of bulk amount of wind energy especially offshore wind energy is attracting utilities to incline towards wind energy. Variable speed wind energy conversion systems employing Doubly fed induction generators offers several advantages such as maximum power generation and independent control of active and reactive powers. Doubly fed induction generator-based wind energy system became the first choice of power system operators due to its low-cost power electronic convertors. Stringent grid codes adopted by various countries made Low voltage ride through a serious problem for electric utilities as well as DFIG manufacturers. Many researchers tried to address the problem of low voltage ride through. In initial stages, crowbar circuits were used. Later Low voltage ride through was addressed using additional hardware such as STATCOM. Artificial intelligent controllers were used to minimize the effect of ride through. A comprehensive review, of different issues allied with low voltage ride through of doubly fed induction generator-based wind energy conversion system is presented in this article.

Improved control strategy for Cuk converter assisted wind‐driven SEIG for DC nanogrid

In this study, the current mode control strategy for a Cuk converter assisted self-excited induction generator-based wind energy conversion system (WECS) for DC nanogrid is proposed. The sliding mode controller (SMC) is a non-linear controller and, is preferred because of good static and dynamic response for input -output disturbance rejections. However, the knowledge of all the state variables is required, which increases the number of sensors and control complexity. To reduce the number of sensors, reduced-order SMC (ROSMC) can be implemented. Conventionally design of the voltage loop in ROSMC does not consider the uncertainty of the control parameter. However, the accuracy of the control signal generated by the ROSMC also depends on how accurately the reference current is generated. Therefore, a genetic algorithm tuned PI controller is proposed to generate the ripple-free reference current. Artificial intelligence assisted ROSMC (AIROSMC) is proposed because of its advantages over SMC, which are a reduced number of sensors, improved dynamic response and easy implementation. The extensive simulation study is carried in MATLAB\Simulink for comparative analysis of fixed frequency SMC, two variable SMC, ROSMC, and AIROSMC. The harmonic spectrum analysis is carried out to justify the selection of DBR instead of the controlled rectifier.

Voltage stability assessment and enhancement of power grid with increasing wind energy penetration

This paper presents the voltage stability assessment of power system with increasing wind energy penetration. The effects of increasing Doubly-Fed Induction Generator-based Wind Energy Conversion System (DFIG-WECS) penetration in the power system have been investigated in this work. Active Power-Voltage (PV) analysis was employed to determine the voltage stability limits in terms of the maximum loadability limit within which stable operation of the grid can be guaranteed as the wind energy penetration increases. The analyses in this work were carried out both for normal and contingency operations of the grid. IEEE 14-bus test system was used as the study case. Simulations were carried out using DigSilent PowerFactory software and results analyses were done using MATLAB. Furthermore, the effects of integrating DFIG-WECS on the loading of essential power system equipment are investigated. The results show that the maximum loadability limit of the study system increases with increasing DFIG-WECS power penetration up to 100%. However, the overloading effects on critical transmission lines presents a definitive limit to the allowable practical penetration level, which is determined to be 28.06%. This limit can be improved to 29.88%, 46.3% and 52.23% by Thyristor-Controlled Series Capacitor (TCSC) application on Line 9–14, upgrading Line 9–14 to double circuit, and upgrading both Line 9–14 and Line 13–14 to double circuit respectively. Thus, effective line enhancement and reactive power compensation strategy such as those offered by FACTS devices are required for a voltage-stable operation of the grid with increasing wind energy penetration.

Grid Ancillary Services From Doubly Fed Induction Generator-Based Wind Energy Conversion System: A Review

Modern electrical grids face serious challenges to maintain healthy operational conditions. The nominal voltage and frequency, for instance, are affected by huge load changes and renewable energy integration. Renewable energy conversion systems are traditionally installed to provide active power. Fortunately, advanced renewable energy conversion systems have the ability to provide other facilities such as reactive power control and harmonic mitigation. In fact, recent grid codes obligate renewable energy systems to serve other duties such as generating reactive power rather than just simply supply active power, participate in fault ride through, for instance. This paper presents a comprehensive study on the doubly fed induction generator (DFIG)-based wind energy conversion system (WECS), which provides ancillary services to the grid along with performing its regular duties. These services include reactive power control, voltage ride through, power quality improvement, frequency control, and power oscillation damping. The literature survey and comparative studies show that the DFIG-based WECS has the ability to support electrical grid during normal and transient conditions, and it can also help in the large-scale renewable energy penetration to the power grid. The effect of different industrial and nonlinear controllers on DFIG performance in extracting grid ancillary services is highlighted.

A new combined actuator fault estimation and accommodation for linear parameter varying system subject to simultaneous and multiple faults: an LMIs approach

This paper proposes a novel fuzzy observer scheme-based active fuzzy fault-tolerant tracking control (FFTTC) combined with a parallel distributed compensation control law for a linear parameter varying system subject to actuator faults and noise measurement. This system consists of a doubly fed induction generator-based wind energy conversion system described by a Takagi–Sugeno fuzzy model. The developed scheme is able to force system states to track their desired reference signal in finite time and obtain a better dynamic response and performance. A fuzzy state observer is also developed to simultaneously estimate the generator states and the actuator faults. Based on the obtained online fault estimation information, the FFTTC will be reconfigured to compensate for the fault impact. The closed-loop stability is established based on a Lyapunov function. Sufficient conditions are formulated for the existence of fuzzy fault-tolerant control parameters in the form of linear matrix inequalities (LMIs), which can be easily solved by means of a standard YALMIP toolbox. The fuzzy observer and fuzzy fault-tolerant tracking control gains can be computed based on the solutions of a set of LMIs. Computer simulations were performed using the MATLAB/Simulink environment to highlight the performance and robustness of the proposed design procedure with respect to actuator fault occurrences.

Active disturbance rejection based MPPT control for wind energy conversion system under uncertain wind velocity changes

The tip speed ratio regulation based maximum power point tracking (MPPT) control for the wind energy conversion system (WECS) is studied in this paper. Challenges imposed by uncertain changes in wind velocity and unmodelled system dynamics are considered. A first order active disturbance rejection controller (ADRC) is designed to tackle this problem. Based on the platform of the high-power (2-MW) rigid-drive-train squirrel-cage induction generator-based wind energy conversion system (WECS), a simulation study is carried out by comparing with the performance of a well-tuned published PI (proportional–integral) speed controller, and the results show that the proposed first order ADRC controller exhibits better tracking performance and adaptability for uncertain wind velocity changes. There are only two controller parameters, namely, ωo and ωc, to tune, and control adaptability can be held without parameters resetting or extractable mechanical power reducing, proving the effectiveness of the proposed ADRC approach for the WECS MPPT problem.

A sliding mode controller-based STATCOM for voltage profile improvement of micro-grids

PurposeThe purpose of this paper is to evaluate the suitability and robustness of sliding mode controller (SMC) for maintaining flat voltage profile at the load bus of two different micro-grid systems using STATCOM.Design/methodology/approachTwo micro-grid systems are dynamically modelled and simulated using MATLAB/Simulink. The first micro-grid has a single diesel engine-driven synchronous generator. The second micro-grid has one diesel engine-driven synchronous generator and a doubly fed induction generator-based wind energy conversion system. The STATCOM is connected to the load bus in both the micro-grids. SMC is used for the control of STATCOM for voltage profile improvement of micro-grid. The performance of SMC-based STATCOM is analysed and compared with the performance of conventional PI controller-based STATCOM.FindingsThe SMCs are more suited for STATCOM control as these are more immune to load disturbances even with the presence of wind energy generators. The voltage deviations and the steady state errors in voltage are less with SMC. Although SMC introduces a bit of steady state error in the dc link voltage of the STATCOM, it is much less than the settling limit of 2 per cent, which is quite acceptable. SMC proves to be better than conventional PI controllers in both the proposed models of micro-grid.Originality/valueDesign of a robust first-order SMC for a STATCOM is used for voltage profile improvement in two different micro-grid systems.

Power Curve Based-Fuzzy Wind Speed Estimation in Wind Energy Conversion Systems

Availability of wind speed information is of great importance for maximization of wind energy extraction in wind energy conversion systems. The wind speed is commonly obtained from a direct measurement employing a number of anemometers installed surrounding the wind turbine. In this paper a sensorless fuzzy wind speed estimator is proposed. The estimator is easy to build without any training or optimization. It works based on the fuzzy logic principles heuristically inferred from the typical wind turbine power curve. The wind speed estimation using the proposed estimator was simulated during the operation of a squirrel-cage induction generator-based wind energy conversion system. The performance of the proposed estimator was verified by the well estimated wind speed obtained under the wind speed variation.

Reliability and performance improvement of double-fed induction generator-based wind energy conversion system

The aim of this paper is to present a new coordination control between active crowbar and PV-STATCOM to enhance the performance and the reliability of grid connected double-fed induction generator (DFIG)-based wind farm under grid disturbance. A new technique to detect the fault is also presented. It is based on monitoring the rotor voltages and currents of the DFIG by using the symmetrical components approach. A modified control scheme of the solar farm converter is adopted to operate as STATCOM in the presence of a disturbance. The proposed control scheme is simulated under MATLAB/Simulink platform to verify its efficiency.