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This article proposes the use of a deep reinforcement learning method—and precisely a variant of the deep deterministic policy gradient (DDPG) method known as twin delayed DDPG, or TD3—for maximum power point tracking in wind energy conversion systems that use permanent magnet synchronous generators (PMSGs). An overview of the TD3 algorithm is provided, together with a detailed description of its implementation and training for the considered application. Simulation results are provided, also including a comparison with a model‐based control method based on feedback linearization and linear‐quadratic regulation. The proposed TD3‐based controller achieves a satisfactory control performance and is more robust to PMSG parameter variations as compared to the presented model‐based method. To the best of the authors' knowledge, this article presents for the first time an approach for generating both speed and current control loops using DRL for wind energy conversion systems. [ABSTRACT FROM AUTHOR]

In this study, the integral linear quadratic regulator (LQR) with servomechanism for machine-side power converter in PMSG-based variable-speed wind energy conversion systems (WECSs) has been proposed. The solution of the algebraic Riccati equation (ARE) has been found for the extended dimension of the state space equation of the system. The state vector has been extended with the integral of the angular shaft speed of the permanent magnet synchronous generator (PMSG) to penalize the errors. The maximum power tracking point (MPPT) algorithm is achieved by minimizing tracking errors between the angular shaft speed reference based on wind speed estimation and its actual values in the variable speed WECS. Also, the estimated aerodynamic torque is used to define the reference electromagnetic torque. This is possible when WECS is partially loaded and pitches angles are fixed at the position to generate maximum power. The mean absolute percentage error of the angular shaft speed of the PMSG-based WECS has been reduced by more than 71% under model uncertainty and noise presented case than in the traditional disturbance observers-based compensation scheme. While the disturbance observers for estimation model uncertainty are eliminated, the use of the high order disturbance observer for aerodynamic torque estimation proved to be necessary to enhance the reliability of wind speed sensors and hence the whole WECS.

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. [ABSTRACT FROM AUTHOR]

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.

In the field of optimizing wind system control approaches and enhancing the quality of electricity generated on the grid, this research makes a fresh addition. The Sliding Mode Control (SMC) technique produces some fairly intriguing outcomes, but it has a severe flaw in the oscillations (phenomenon of reluctance: chattering) that diminish the system's efficiency. In this paper, an AST (adaptive super twisting) approach is proposed to control the wind energy conversion system of the permanent magnet synchronous generator (PMSG), which is connected to the electrical system via two converters (grid-side and machine-side) and a capacitor serves as a DC link between them. This research seeks to regulate the generator and grid-side converter to monitor the wind rate reference given by the MPPT technique in order to eliminate the occurrence of the chattering phenomenon. With the help of this approach, precision and stability flaws will be resolved, and the wind system will perform significantly better in terms of productivity. To evaluate the performance of each control in terms of reference tracking, response time, stability, and the quality of the signal sent to the network under different wind conditions, a detailed description of the individual controls is given, preceded by a simulation in the Matlab/Simulink environment. The simulation study validates the control method and demonstrates that the AST control based on the Lyapunov stability theory provides excellent THD and power factor results. This work is completed by a comparative analysis of the other commands to identify the effect on the PMSG wind energy conversion system. [ABSTRACT FROM AUTHOR]

This article proposes an approach and develops an appropriate method of applying linear non-equilibrium thermodynamics to analyze energy processes, in particular using the example of the wind energy conversion system (WECS) with a directly connected vertical axis wind turbine (VAWT) and vector-controlled permanent magnet synchronous generator (PMSG). The main steps of the proposed approach are the description of the component subsystems as universal linear or linearized energy converters (ECs), which are characterized by several dimensionless parameters, the main one of which is the degree of coupling between their input and output. According to their value, as well as justified efficiency criteria, the optimal operating points of each ECs can be easily found. Such an approach makes it possible to abstract from physical laws of a different nature and equally assess the work of each of the subsystems. The next step is a connection of the received ECs. As shown in the paper, for the most common cascade connection of ECs, there are the best conditions for their connection, under which the newly formed equivalent EC can have maximum efficiency. This opens up an opportunity to analyze the influence of already real parameters of cascaded interconnected subsystems on the quality of their connection and justify specific solutions that would not have been seen without this approach. For example, in this study, from all parameters of the PMSG, only the selection of the optimal rated inductance of the armature winding made it possible to improve the quality of the connection of the PMSG with a specific VAWT and approximate the efficiency of the entire WECS to the maximum possible, especially in medium and high winds. [ABSTRACT FROM AUTHOR]

In this paper, a wind energy conversion system (WECS) is presented for the electrification of rural areas with wind energy availability. A three-phase AC-DC converter based on a bridgeless Cuk converter is used for power extraction from the permanent magnet synchronous generator (PMSG). The bridgeless topology enables the elimination of the front-end diode bridge rectifier (DBR). Moreover, the converter has fewer components, simple control, and high efficiency, making it suitable for a small-scale WECS. A squirrel cage induction motor (SCIM) is used to emulate a MOD-2 wind turbine to implement the PMSG-based WECS. A direct-drive eight-pole PMSG is used in this study; thus, a low-input-voltage system is designed. The converter is designed to operate in the discontinuous inductor current mode (DICM) for inherent power factor correction (PFC) and the maximum power point tracking (MPPT) is achieved through the tip-speed ratio (TSR) following. The performance of the developed system is analyzed through simulation, and a 500 W hardware prototype is developed and tested in different wind speed conditions.

This article proposes an approach and develops an appropriate method of applying linear non-equilibrium thermodynamics to analyze energy processes, in particular using the example of the wind energy conversion system (WECS) with a directly connected vertical axis wind turbine (VAWT) and vector-controlled permanent magnet synchronous generator (PMSG). The main steps of the proposed approach are the description of the component subsystems as universal linear or linearized energy converters (ECs), which are characterized by several dimensionless parameters, the main one of which is the degree of coupling between their input and output. According to their value, as well as justified efficiency criteria, the optimal operating points of each ECs can be easily found. Such an approach makes it possible to abstract from physical laws of a different nature and equally assess the work of each of the subsystems. The next step is a connection of the received ECs. As shown in the paper, for the most common cascade connection of ECs, there are the best conditions for their connection, under which the newly formed equivalent EC can have maximum efficiency. This opens up an opportunity to analyze the influence of already real parameters of cascaded interconnected subsystems on the quality of their connection and justify specific solutions that would not have been seen without this approach. For example, in this study, from all parameters of the PMSG, only the selection of the optimal rated inductance of the armature winding made it possible to improve the quality of the connection of the PMSG with a specific VAWT and approximate the efficiency of the entire WECS to the maximum possible, especially in medium and high winds.

This paper focuses on the performance analysis, modeling, and control of permanent magnet synchronous generator (PMSG)-based wind energy conversion. This work analyzes controllers for the machine-side converter (MSC) and grid-side converter (GSC) and presents a new direct torque control (DTC) scheme based on a 12-sectors polygonal DTC for variable speed control of the PMSG. The proposed method solves the drawbacks faced by conventional six-sectors DTC control. The proposed method utilizes 12 sectors of 30° each compared to 60° in the conventional 6-sectors DTC. The 12-sectors technique was applied to voltages and flux vectors to increase the degrees of freedom for the selection of optimal vectors and, thus, reduce the torque ripple. This work analyzed the aforementioned DTC methods using MATLAB/Simulink, comparing the dynamic response of the proposed 12-sectors DTC with the conventional 6-sectors DTC control, and the results verified the effectiveness of the proposed DTC control. [ABSTRACT FROM AUTHOR]

Utilization of small-scale wind energy conversion systems (WECS) has been grown in recent years. Permanent magnet synchronous generator due to lack of slip rings is a suitable alternative for induction generators to be used in these systems. However, these generators use full power converters which means higher power losses. In this paper, an ultra-efficient three-level converter, called T-type converter, is used in a back-to-back configuration as power electronic interface for PMSG-based small-scale WECS. Then, simulations are carried out to evaluate the efficiency of the system and compare it to conventional two- and three-level back-to-back configurations. Meanwhile, thermal analysis is carried out to investigate the thermal loading of different switching components of the converter. Data given by this analysis can be further used to evaluate system reliability. Therefore, system reliability is calculated and compared to conventional two- and three-level converter systems. [ABSTRACT FROM AUTHOR]

This paper proposes a novel integral sliding mode control (ISMC) scheme based on numerically solving a state-dependent Ricatti equation (SDRE), nonlinear feedback control for wind energy conversion systems (WECSs) with permanent magnet synchronous generators (PMSGs). Unlike the conventional ISMC, the proposed control system is designed with nonlinear near optimal feedback control part to take into account nonlinearities of the WECSs. The Taylor series are used to approximate the solutions of SDRE. More specifically, the nonlinear optimal feedback control has been obtained by solving continuous algebraic Ricatti and Lyapunov equations. Sliding variables are designed such that reaching phase is eliminated and stability is guaranteed. The proposed control method equipped with high-order observer can guarantee more superior results than linear techniques such as linear quadratic regulator (LQR), conventional ISMC, and first-order sliding-mode control (SMC) method. Increasing the number of terms of the Taylor's series of the proposed control law provides better approximation, therefore the performance is improved. However, this increases the computational burden. The effectiveness of the control method is validated via simulations in MATLAB/Simulink under nominal parameters and model uncertainties.

This paper focuses on the control problem of wind energy conversion systems (WECSs) with direct-driven permanent magnet synchronous generator (PMSG) working in variable power output stage. A novel compound control scheme combined the active disturbance rejection controller (ADRC) and speed sensorless technology is proposed. In order to achieve maximum power point tracking (MPPT), a speed control loop is designed based on ADRC to improve the speed tracking ability and anti-disturbance ability of system. Moreover, considering the large amount of system model information, a model-assisted ADRC is designed on the nominal ADRC to improve the response speed of system and reduce the energy consumption for the system control. Additionally, to solve the contradiction between the requirement of speed sensor precision and the economy of system design, a speed observer based on current model is designed in α - β coordinate system. Furthermore, a resistance observer is introduced to improve the convergence rate of the observer. And a position sensorless observer structure based on the speed observer is proposed. Finally, simulation studies are conducted to evaluate power tracking performances of the proposed speed-observer-based model assisted ADRC technology. It is shown that the proposed compound scheme exhibits significant improvements in both control performance and anti-disturbance ability with high observation precision compared with the normal ADRC method.

This paper focuses on the performance analysis, modeling, and control of permanent magnet synchronous generator (PMSG)-based wind energy conversion. This work analyzes controllers for the machine-side converter (MSC) and grid-side converter (GSC) and presents a new direct torque control (DTC) scheme based on a 12-sectors polygonal DTC for variable speed control of the PMSG. The proposed method solves the drawbacks faced by conventional six-sectors DTC control. The proposed method utilizes 12 sectors of 30° each compared to 60° in the conventional 6-sectors DTC. The 12-sectors technique was applied to voltages and flux vectors to increase the degrees of freedom for the selection of optimal vectors and, thus, reduce the torque ripple. This work analyzed the aforementioned DTC methods using MATLAB/Simulink, comparing the dynamic response of the proposed 12-sectors DTC with the conventional 6-sectors DTC control, and the results verified the effectiveness of the proposed DTC control.

The electrical power extracted from a wind energy conversion system (WECS) tends to be inconsistent due to the intermittent nature of the wind. This issue is addressed by formulating a maximum power point tracking (MPPT) control strategy that optimizes the power extraction from the WECS under a wide range of wind speed profiles. This research article focuses on the formulation of a nonlinear neuro-adaptive backstepping integral sliding mode control (NABISMC) based MPPT strategy for a standalone, variable speed, fixed-pitch WECS equipped with a permanent magnet synchronous generator (PMSG). The proposed paradigm is a hybrid of the conventional backstepping and the integral sliding mode control (ISMC) based MPPT schemes. The effectiveness of the control strategy devised is guaranteed through numerical simulations carried out in Matlab/Simulink for a 3 kW PMSG-WECS under a stochastic wind speed profile. Further validation is guaranteed by giving a detailed performance comparison analysis of the proposed MPPT control strategy with the conventional feedback linearization control (FBLC), proportional integral derivative (PID) control, sliding mode control (SMC), and standard neuro-adaptive integral sliding mode control (NAISMC) based MPPT strategies, where the proposed strategy is found superior to all the stated strategies in terms of offering more accurate MPPT, lower steady state error, faster dynamic response and lesser chattering. [ABSTRACT FROM AUTHOR]

This paper deals with a wind energy conversion system connected with grid. In this system rotor side and grid side converters are used to cope with reactive powers generated and to get the balanced output at the load side. A very effective control technique has been developed based on pulse width modulation to make the line voltages at the point of common coupling. Various filters have been used in this system and according to different filter parameters and design, the total harmonic distortion (THD) has been compared and calculated accordingly. [ABSTRACT FROM AUTHOR]

Due to the intermittent nature of wind, there exists a major disparity between the power generation from the wind and the demand of electricity. Hence, a sophisticated maximum power point tracking (MPPT) control paradigm must be formulated for maximizing the power extraction from the wind. This research article focuses on the formulation of a nonlinear fast dynamic terminal sliding mode control (FDTSMC)-based MPPT strategy for optimizing the power extraction from a 3kW, variable speed, fixed-pitch wind energy conversion system equipped with a permanent magnet synchronous generator. The proposed MPPT strategy is compared with the benchmark fast terminal sliding mode control, conventional sliding mode control, feedback linearization control and proportional integral derivative control-based MPPT strategies under a stochastic wind speed profile. The proposed paradigm has been found superior in its tracking performance by converging the output tracking error to zero in a finite time, realizing a high precision performance, offering fast dynamic response, reducing the chattering to a minute level and guaranteeing global robustness. The superior performance and effectiveness of the proposed FDTSMC-based MPPT control paradigm is tested and validated through extensive MATLAB/Simulink simulations. [ABSTRACT FROM AUTHOR]

Wind energy conversion systems (WECSs) based on synchronous generators devoid of rotor windings, such as permanent magnet synchronous generators and synchronous reluctance generators, have become popular due to their maintenance-free operation. As per grid codes, WECSs ought to stay connected, at least for a short while, to ensure reliability and stability, even if there is a fault in the grid. There are various techniques proposed in the literature, for implementing low-voltage ride-through (LVRT). This article explores a few methods for achieving LVRT for a synchronous machine-based WECS connected to the grid through a back-to-back connected full-rated converter. The machine-side converter is controlled by field-oriented control methodology to drive the generator at an optimum speed to harvest maximum power from the wind turbine. The grid-side converter makes use of the grid-voltage-oriented control algorithm to achieve decoupled control of real and reactive powers. The LVRT capability of the system is attained using four different control techniques, namely modulation index (MI) control, deloading, crow-bar protection, and interchanging the roles of the two converters to arrest the rise in dc-link voltage. These methods have been simulated in Simulink/MATLAB environment, and the results obtained show that these techniques work very effectively for realizing LVRT in a synchronous machine-based WECS. Finally, experimental results are presented to demonstrate the successful working of the maximum power point tracking algorithm and LVRT capability on a laboratory prototype; a comparison of LVRT techniques is presented to enable the users to make an informed choice. [ABSTRACT FROM AUTHOR]

Fast transient and smooth steady-state performance of wind energy conversion systems (WECSs) is essential for sustained power conversion and grid code fulfilment including low voltage ride through capability. In this paper, an analysis of permanent magnet synchronous generator (PMSG)-based WECSs under vector control and direct torque control provides the basis for combining salient features of the two control methods into a reliable and effective control system to provide enhanced machine performance. The system includes two hysteresis current controllers in connection with an inverter-switching table. The proposed control provides fast transient and smooth steady-state performance for machine side converter of PMSGs, which controls dc-link voltage under grid fault conditions. Extensive simulation results on a 2-MW PMSG-based WECS demonstrate the desired performance of the proposed control system under both grid-normal and -fault conditions. [ABSTRACT FROM AUTHOR]

Various challenges are acknowledged in practical cases with high wind power penetration. Fault ride-through (FRT) capability has become the most dominant grid integration requirements for the wind energy conversion system worldwide. The high voltage ride-through (HVRT) and low voltage ride-through (LVRT) performance play a vital role in the grid-friendly integration into the system. In this paper, a coordinated HVRT and LVRT control strategy is proposed to enhance the FRT capability of the permanent magnet synchronous generator (PMSG)-based wind turbine generators (WTG). A dual-mode chopper protection is developed to avoid DC-link overvoltage, and a deadband protection is proposed to prevent oscillations under edge voltage conditions. The proposed strategy can ride through different levels of voltage sags or swells and provide auxiliary dynamic reactive power support simultaneously. The performance of the proposed control scheme is validated through various comparison case tests in PSCAD/EMTDC.

Due to the intermittent nature of wind, there exists a major disparity between the power generation from the wind and the demand of electricity. Hence, a sophisticated maximum power point tracking (MPPT) control paradigm must be formulated for maximizing the power extraction from the wind. This research article focuses on the formulation of a nonlinear fast dynamic terminal sliding mode control (FDTSMC)-based MPPT strategy for optimizing the power extraction from a 3kW, variable speed, fixed-pitch wind energy conversion system equipped with a permanent magnet synchronous generator. The proposed MPPT strategy is compared with the benchmark fast terminal sliding mode control, conventional sliding mode control, feedback linearization control and proportional integral derivative control-based MPPT strategies under a stochastic wind speed profile. The proposed paradigm has been found superior in its tracking performance by converging the output tracking error to zero in a finite time, realizing a high precision performance, offering fast dynamic response, reducing the chattering to a minute level and guaranteeing global robustness. The superior performance and effectiveness of the proposed FDTSMC-based MPPT control paradigm is tested and validated through extensive MATLAB/Simulink simulations.

In this paper, the Predictive Current Control (PCC) strategy for back-to-back (BTB) voltage source converters used in Permanent Magnet Synchronous Generator (PMSG), Wind Energy Conversion System (WECS) was explained. PCC is used to control the system, where the discrete time models of the BTB converters are used to predict the future state of control variables. Two cost functions are used to evaluate these predictions, and switching states which will minimize these cost functions will be selected and applied to generator side and grid side converter. The control requirements like Maximum Power Point Tracking (MPPT), Direct Current (DC) link voltage regulation and reactive power generation to the grid are satisfied by the PCC approach. Complete procedure for the MATLAB/Simulink implementation of predictive model, extrapolation and cost function employed in the implementation of PCC scheme are presented along with the comparison of the performance of Wind Energy Conversion System (PMSG WECS) and back-to-back (BTB) converter with conventional control technique. [ABSTRACT FROM AUTHOR]

This paper presents a fault detection and isolation system for additive and multiplicative faults for current and voltage measurements of a controlled wind energy conversion system (WECS). The method is based on an observer scheme, comprised of a time-varying Kalman filter and a maximum-shift strategy, to generate new residuals capable of detecting all fault types especially multiplicative ones with low gains. The detection system has been experimentally validated on a WECS driven by a permanent magnet synchronous generator, and experimental results have proved its effectiveness. [ABSTRACT FROM AUTHOR]

Advanced control algorithms must be used to make wind power generation truly cost effective and reliable. In this study, we develop a new and simple control scheme that employs model predictive control (MPC), which is used in permanent magnet synchronous generators and grid-connected inverters. The proposed control law is based on two points, namely, MPC-based torque-current control loop is used for the generator-side converter to reach the maximum power point of the wind turbine, and MPC-based direct power control loop is used for the grid-side converter to satisfy the grid code and help improve system stability. Moreover, a simple prediction scheme is developed for the direct-drive wind energy conversion system (WECS) to reduce the computation burden for real-time applications. A small-scale WECS laboratory prototype is built and evaluated to verify the validity of the developed control methods. Acceptable results are obtained from the real-time implementation of the proposed MPC methods for WECS. [ABSTRACT FROM AUTHOR]

This paper proposes a novel optimal current given (OCG) maximum power point tracking (MPPT) control strategy based on the theory of power feedback and hill climb searching (HCS) for a permanent magnet direct drive wind energy conversion system (WECS). The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG) is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR) MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.

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. [ABSTRACT FROM AUTHOR]

The growing trends in wind energy technology are motivating the researchers to work in this area with the aim towards the optimization of the energy extraction from the wind and the injection of the quality power into the grid. Over the last few years, wind generators based on permanent magnet synchronous machines (PMSMs) are becoming the most popular solution for the modern wind energy conversion systems (WECSs). This paper presents a concise review of the grid-integrated WECSs employing permanent magnet synchronous generators (PMSGs). It reviews the trends in converter topologies, control methodologies, and methods for maximum energy extraction in PMSG based WECSs, which have been reported in various research literatures primarily in reputed research journals and transactions during last few years. It also presents an overview to the grid interconnection issues related to output power smoothing and reactive power control in addition to fault-ride-through (FRT) and grid support capabilities of PMSG based WECSs. This review article will serve the researchers working in the area of grid-integrated PMSG based WECSs in the exploration of trends, developments and challenges in the past research works and in finding out the relevant references for their research work. [ABSTRACT FROM AUTHOR]

The headway of wind power generation is a great blessing to help meet up the electrical power demand day by day. The strongest challenges for wind energy conversion system (WECS) are to handle the intermittency of wind and to maintain the grid reliability. The power electronics and energy storage systems are essential elements of the WECS. This paper attempts to provide various new directions to the future wind energy researchers to improve the wind turbine aerodynamics, electric generators׳ configurations with improved control of power electronics and lower cost energy storage system for designing a reliable wind turbine generator system. This study will work as a guideline for the researchers to understand the development and requirement of a reliable and smart wind energy conversion system. [ABSTRACT FROM AUTHOR]

In this paper, a new medium voltage power converter topology using a diode rectifier, three-level boost (TLB) converter, and neutral-point-clamped (NPC) inverter is proposed for a high-power permanent magnet synchronous generator-based wind energy conversion system. The generator-side TLB converter performs the maximum power point tracking and balancing of dc-link capacitor voltages, while the grid-side NPC inverter regulates the net dc-bus voltage and reactive power to the grid. A significant improvement in the grid power quality is accomplished as the NPC inverter no longer controls the dc-link neutral point voltage. A model predictive strategy is proposed to control the complete system where the discrete-time models of the proposed power electronic converters are used to predict the future behavior of control variables. These predictions are evaluated using two independent cost functions, and the switching states which minimize these cost functions are selected and applied to the generator- and grid-side converters directly. In order to comply with the high-power application, the switching frequencies of the TLB converter and NPC inverter are minimized and maintained below 1.5 and 1 kHz, respectively. The proposed topology and control strategy are verified through MATLAB simulations on a 3-MW/3000-V/577-A system and dSPACE DS1103-based experiments on 3.6-kW/208-V/10-A prototype. [ABSTRACT FROM AUTHOR]

In the wind energy conversion system (WECS) based on the permanent magnet synchronous generator, the topology that a wind generator is connected to a voltage source inverter through a diode rectifier and a boost chopper is widely adopted for its low cost and high reliability. However, with the increasing power level of the WECS, the power switch device of a boost chopper in the topology has to endure high instantaneous voltage and current stress, thus reducing the system reliability. Although the traditional multiple boost converter reduces the transmission power level of single circuit units in terms of structure, it is still limited by narrow speed regulation range. Thus, a novel switchable-cascaded-mode boost chopper is proposed in this paper. The operation principle of the new converter and the generator speed control strategy are analyzed. At last, the effectiveness of the new converter is verified with an experimental prototype. The experimental results demonstrate that speed range is extended by using the new topology as generator-side converter in the permanent magnet wind generation system. [ABSTRACT FROM AUTHOR]

Abstract: The grid connected Wind Energy Conversion Systems (WECSs) have two practical topologies, the traditional fixed speed and the new variable speed. Variable speed systems have several advantages over the traditional ones, such as reduction of mechanical stress and increase in captured energy; however, the systems need a Power Electronic (PE) converter, in which the machine is connected to the grid via the PE converter. To improve the power quality and decrease electrical losses in the variable speed WECS, choosing a full control PE converter or a simple PE converter including an active filter is essential. In this paper, a new modulation technique is proposed to be used in a Shunt Active Filter (SAF) to improve the output current harmonics of a WECS, including a Permanent Magnet Synchronous Generator (PMSG) and the AC-to-DC converter. The filter contains three parts: the identification, modulation, and an inverter. Most identification methods are sensitive to non-sinusoidal sources, but in the proposed filter an algorithm is used to make it non-sensitive to some extent. The simulation results confirm the superior performance of the proposed SAF over the previous SAFs applied in wind energy conversion systems. [Copyright &y& Elsevier]