Permanent Magnet Synchronous Generator-based Wind Research Articles

Takagi-Sugeno fuzzy sampled-data observer design for nonlinear permanent magnet synchronous generator-based wind turbine systems using auxiliary function-based integral inequality technique

This study focuses on designing the fuzzy sampled-data observer (FSDO) scheme for nonlinear permanent magnet synchronous generator (PMSG)-based wind turbine systems (WTS). The primary objective of this problem is to solve an unmeasurable state problem under the mismatched premise variables conditions among system, observer, and controller, respectively. To do this, firstly, the proposed wind turbine model is described in a Takagi-Sugeno fuzzy model due to the complex nonlinearities in PMSG-based WTS. Next, based on the measured output signals and sampled estimated states, the FSDO is designed to understand some unmeasurable state variables of the studied system. Then, a novel auxiliary function-based integral inequality (AFBII) is presented to approximate the integral quadratic terms related to sampling information. Thanks to the proposed AFBII technique and the introduction of slack variables, several new and less conservative stability requirements are derived in the formulations of linear matrix inequalities (LMIs) using the looped Lyapunov function. Finally, the simulation studies for the considered wind turbine model are validated numerically, and then some comparative results are provided to show the superiority and applicability of the theoretical observations.

Nonlinear Quadratic Regulator Design With a Hybrid Switching Scheme for Wind Turbine Generators

This article proposes a new control scheme with a nonlinear quadratic regulator (NQR) associated with a hybrid switching stage for permanent magnet synchronous generator-based wind turbines (WTs). The proposed method shows a new approach combining a nonlinear optimal control method with a hybrid switching stage for WT generations (WTGs). As the WTG is a nonlinear system, NQR control design is directly employed to deal with the nonlinearity while a hybrid switching scheme can deal with constrained control inputs as discrete nonlinear characteristics of switch-mode power converters. A polynomial-based dynamic model is derived for the new NQR design. Unlike the previous state-dependent Riccatti equation (SDRE) technique where the solution of the nonlinear optimal controller is approximated, this technique finds the exact online solution of SDRE with nonlinear feedback gains flexibly depending on the tracking error. Then, the optimal control laws are implemented via a hybrid switching stage ensuring a smooth current regulation under a reduced switching frequency while avoiding any complicated modulator or finite state search. The proposed control design is investigated via comparative studies with linear quadratic regulator (LQR), direct switching, and space-vector pulse-width-modulation stages (SV-PWMs) implemented in both platforms of MATLAB/Simulink and real-time OPAL-RT. Comparative results exhibit flexible optimal performances via online hyper-parameter tuning to reduce the speed tracking error and low current ripples under a reduced switching frequency.

Enhancing Single-Phase Grid Integration Capability of PMSG-Based Wind Turbines to Support Grid Operation under Adverse Conditions

The proposed work delivers a robust control solution for a single-phase permanent magnet synchronous generator-based wind power conversion system (PMSG-WPCS) to enhance grid integration capability. The proposed control approach also offers an extended facility to fulfill low-voltage fault ride-through (LVRT) requirements under adverse grid conditions. Unlike the conventional observer-based PLL (O-PLL) approach, the proposed improved Lyapunov theory-based prefilter (ILP) is helpful in yielding a quadrature signal to solve the single-phase grid synchronization problem. Moreover, the proposed prefilter can leverage delayed signal operation, which improves the harmonic and the DC-offset component rejection abilities while eliminating the need for internal feedback-based submodule blocks for the case of an O-PLL. Consequently, the proposed ILP-PLL exhibits better dynamic behavior to rapidly synchronize a grid-tied power converter and can accurately track the fundamental amplitude information that is required for inverter control to meet the fault ride-through requirements. In addition, the suggested LVRT controller ensures smooth transition between the unity and non-unity power factor modes for superior converter control over reactive current injection into the grid to recover the grid from faults while maintaining a lower amount of total harmonic current distortions. The dynamic performance of the proposed control scheme is experimentally validated in view of the existing O-PLL approach for lower-rating wind-turbine-based PMSG-WPCS.

Certainty equivalence-based robust sliding mode control strategy and its application to uncertain PMSG-WECS.

This work focuses on maximum power extraction via certainty equivalence-based robust sliding mode control protocols for an uncertain Permanent Magnet Synchronous Generator-based Wind Energy Conversion System (PMSG-WECS). The considered system is subjected to both structured and unstructured disturbances, which may occur through the input channel. Initially, the PMSG-WECS system is transformed into a Bronwsky form, i.e., controllable canonical form, which is composed of both internal and visible dynamics. The internal dynamics are proved stable, i.e., the system is in the minimum phase. However, the control of visible dynamics, to track the desired trajectory, is the main concern. To carry out this task, the certainty equivalence-based control strategies, i.e., conventional sliding mode control, terminal sliding mode control and integral sliding mode control are designed. Consequently, a chattering phenomenon is suppressed by the employment of equivalent estimated disturbances, which also enhance the robustness of the proposed control strategies. Eventually, a comprehensive stability analysis of the proposed control techniques is presented. All the theoretical claims are verified via computer simulations, which are performed in MATLAB/Simulink.

Efficiency, Cost, and Volume Comparison of SiC-Based and IGBT-Based Full-Scale Converter in PMSG Wind Turbine

Power electronics, as an enabling technology in most renewable energy systems, is gaining attention as the penetration of renewable energy sources increases. Wide-bandgap power electronics are of particular interest due to their superior voltage blocking capabilities and fast switching speeds. They can viably be considered in the renewable energy sources, especially as the penetration of wind energy is expected to increase by a great extent in the upcoming years. In this paper, a comparison of Silicon Carbide-based and Silicon-based wind energy conversion systems has been performed, as it is crucial in understanding the benefits of adopting wide-bandgap-based solutions at a commercial level. For this analysis, a 2 MW permanent magnet synchronous generator-based wind conversion system with a bidirectional full-scale frequency converter comprised of two back-to-back inverters is considered. The efficiency, cost, and total volume of the passive components comparison have been conducted for Silicon- and Silicon Carbide-based converters. The comparison presented is a fair comparison, meaning that the converters are designed with modules of the same power ratings. Wind energy systems are compared both for the same switching frequency (low switching frequency suitable for IGBT modules) and also considering a Silicon Carbide-MOSFET-based converter working at high switching frequencies. The comparison is performed in PLECS simulation tool, using the PLECS libraries for different modules obtained from the manufacturers’ experimental data. The results show the benefits of using the Silicon Carbide-based converter when it comes to volume reduction in the passive components and provide insights to what is missing in order to achieve overall system volume and cost savings.

Stable Maximum Power Extraction and DC Link Voltage Regulation for PMVG-Based WECS

This study discusses the power maximization and dc-link voltage regulation problems of a permanent magnet vernier generator (PMVG)-based wind energy conversion system. To do this, first, the dynamical model of PMVG-based wind turbine is developed and presented. Then, the overall control structure is configured utilizing a back-to-back converter with a machine-side converter (MSC) and a grid-side converter (GSC). At this time, the sliding-mode control scheme with the modified enhanced exponential reaching law is proposed for both MSC and GSC control to achieve maximum power extraction and stable dc link voltage, respectively. Furthermore, the sliding manifold’s stability condition is derived using the Lyapunov function, which guarantees a better transient performance and tracking accuracy. Finally, the proposed control scheme’s superiority and efficiency are demonstrated using theoretical simulations on 5 kW PMVG-based and 1.5 MW permanent magnet synchronous generator-based wind turbine systems and empirical findings derived from a grid-connected 5 kW PMVG-based wind turbine in the experimental setup.

Unified Power Control of Permanent Magnet Synchronous Generator Based Wind Power System with Ancillary Support during Grid Faults

A unified active power control scheme is devised for the grid-integrated permanent magnet synchronous generator-based wind power system (WPS) to follow the Indian electricity grid code requirements. The objective of this paper is to propose control schemes to ensure the continuous integration of WPS into the grid even during a higher percentage of voltage dip. In this context, primarily a constructive reactive power reference is formulated to raise and equalize the point of common coupling (PCC) potential during symmetrical and asymmetrical faults, respectively. A simple active power reference is also proposed to inject a consistent percentage of generated power even during faults without violating system ratings. Eventually, the efficacy of the proposed scheme is demonstrated in terms of PCC voltage enhancement, DC-link potential, grid real, and reactive power oscillation minimization using the PSCAD/ EMTDC software.

A new predictive control strategy for improving operating performance of a permanent magnet synchronous generator-based wind energy and superconducting magnetic energy storage hybrid system integrated with grid

This research work proposes an unscented Kalman filter (UKF) as an observer for predictive current control (PCC) of a permanent magnetic synchronous generator (PMSG)-based wind energy conversion system (WECS) connected with a superconducting magnetic energy storage (SMES) system and the main power grid. The proposed UKF observer estimates the rotor angle, rotor angular speed, stator currents, and electromagnetic torque of PMSG connected in the proposed hybrid WECS-SMES configuration. The PCCs designed for both the rotor- and grid- side converters of the proposed hybrid configuration use estimated parameters instead of the measured quantities. Furthermore, due to the intermittent nature of wind energy, control of an energy storage device (which is SMES in this research) is necessary to mitigate the fluctuations in the DC-link voltage and output power being sent to the main power grid. Therefore, a novel control configuration based on fractional order-PI (FOPI) controllers has also been proposed for the SMES system to control the output power and the DC-link voltage. An artificial bee colony optimization algorithm has been used to tune the gains and integration operators of two FOPI controllers. For UKF estimation performance comparison, three popular observers i.e., Luenberger, sliding mode, and extended Kalman filter, have also been designed and implemented in MATLAB. Mean absolute percentage error and root mean squared error performance metrics are used to measure the estimation performance. The simulated results have demonstrated the superior performance of proposed the UKF observer for PCC and FOPI controllers for SMES under different realistic wind speed conditions and noisy measurements. The proposed UKF observer has improved estimation by up to 99.9 %. Lyapunov stability criteria are used to prove the stability of the proposed UKF based PCC control of hybrid WECS-SMES configuration.

Frequency Trajectory Planning-based Frequency Regulation Strategy for Wind Turbines Equipped with Energy Storage System

The increase in wind power penetration has weakened the equivalent inertia of the power system, posing a significant challenge to frequency stability. In this paper, a frequency trajectory planning (FTP)-based frequency regulation (FR) strategy is proposed for permanent magnet synchronous generator-based wind turbines equipped with an energy storage system (ESS) on the DC link. The core idea is that the frequency index provided by the grid code is used to plan a safe frequency trajectory when the system frequency fluctuates. The FR power provided by the ESS is controlled by tracking the planned frequency trajectory to compensate for the unbalanced power in the system, provide inertia support, and ensure the frequency stability of the power grid. The proposed strategy can suppress the frequency fluctuation and optimize the FR power of the ESS. It also effectively circumvents the complex parameter design process of virtual inertia control. The simulation model is established in Matlab/Simulink to verify the effectiveness of the control strategy.

An improved control method of fault ride-through for DPMWT-based wind farm considering coupling effect of HVDC transmission system

With the continuous increase of wind power penetration, a large number of wind farm have been constructed. The large-scale wind farm is usually transmitted through high voltage direct current(HVDC) transmission system. The reactive power output on the grid-side converter is utilized to support grid voltage, which is a common method of fault ride-through for direct-drive permanent magnet synchronous generator-based wind turbine (DPMWT). The power control capability of DPMWT-based wind farm(DPMWF) is affected by safety constraints and operating characteristics of the external system. However, the control strategy of DPMWF cannot yet take into account the coupling effect of HVDC and may be difficult to meet the voltage recovery requirements of the grid during the grid fault. Even the DPMWT may oscillate due to the over-threshold of the control setting value. Therefore, a power coupling model between DPMWF and rectifier station of HVDC transmission system is established, and an evaluation method for the power controllability of DPMWF under fault considering the coupling effect of HVDC transmission system is proposed. A calculation method of maximum reference value of reactive power control of DPMWF based on model predictive control is proposed taking into account the converter constraints of DPMWF and the influence of the external system. An improved control method of fault ride-through is further proposed, which takes into account the coupling effect of HVDC transmission system. The simulation shows that the proposed method can improve the voltage recovery characteristics under the grid fault, effectively guarantee the fault ride-through of DPMWF.

Coordinated Control of Grid-Connected PMSG Based Wind Energy System With STATCOM and Supercapacitor Energy Storage

In this paper, two coordinated control schemes have been designed for a grid-connected permanent magnet synchronous generator-based wind energy conversion system with static synchronous compensator (STATCOM) and supercapacitor energy storage (SCES) under various operating conditions. The coordinated control scheme-I (CCS-I) integrated a SCES into the DC-link through a bidirectional DC/DC converter to stabilize the DC-link voltage under varying wind speed and grid disturbances. The coordinated control scheme-II (CCS-II) implemented a STATCOM at the point of common coupling (PCC) to enhance the grid voltage stability during the grid voltage sag or swell. In CCS-II the SCES balances the active power while reactive power support is extracted from the grid side converter (GSC). The STATCOM is only activated when the reactive power requirement by the PCC exceeds the support capacity of the GSC. The proposed coordinated control schemes have been experimentally implemented with a dSpace MicroLabBox. Results show that CCS-I and II ensured the uninterrupted operation of the wind energy system and satisfied grid code requirements under various operating conditions and grid disturbances.

Reinforcement Learning-Based Adaptive Optimal Fuzzy MPPT Control for Variable Speed Wind Turbine

A reinforcement learning-based adaptive optimal fuzzy controller is proposed for maximum power point tracking (MPPT) control of a variable-speed permanent magnet synchronous generator-based wind energy generation system. The algorithm consists of a critic, an adaptive optimal fuzzy controller, and an adaptive optimal fuzzy estimator. The critic is built based on an adaptive neuro-fuzzy inference system (ANFIS) network instead of the neural network as normal to reduce the computation. The error between the system output and the estimator output is used as the input of the critic. In addition, the critic is used to calculate the update law for the parameters of the adaptive optimal fuzzy controller and adaptive optimal fuzzy estimator based on minimizing the input error function. Moreover, the proposed control scheme is output feedback instead of state feedback, which does not require a system model as well as system parameters, so the system is robust to uncertainties and external disturbances. Besides, the stabilization proof is accomplished by using the Lyapunov stability theorem for the closed-loop system and the convergence of the update law. Finally, the effectiveness of the proposed reinforcement learning-based adaptive optimal fuzzy control scheme is verified through simulation with various scenarios such as step wind speed, random wind speed, and system parameter variations. Also, the comparisons with other control schemes in the state-of-art (neural network reinforcement learning based adaptive optimal fuzzy controller, PI controller) are executed to demonstrate the advantages of the proposed control scheme.

Control of wide-speed-range operation for a permanent magnet synchronous generator-based wind turbine generator at high wind speeds

Wind turbine generators (WTGs) contain plenty of inertia in their rotating masses, which has great potential for exploitation. Traditionally, WTGs are operated with the rated rotational speed at high wind speeds, which cannot accelerate further to absorb kinetic energy (KE). In this paper, a control method achieving a wide-speed-range operation for a permanent magnet synchronous generator (PMSG)-based WTG at high wind speeds is proposed. The proposed method can permit the WTG to operate steadily at any desired speed over an allowable range, rather than fixed to the rated speed. Thus, the rotating masses can not only decelerate to release substantial KE as previous works, but also accelerate to absorb considerable KE, which acts as a flexible virtual flywheel energy storage system (VFESS). The equivalent capacity of the VFESS is analyzed in theory, based on the analysis for feasible operation range of rotational speed at high wind speeds. The performance of the proposed control method is verified considering normal operation, extra active power demand and low voltage ride through scenarios, based on EMTP-RV generated data. The results demonstrate that the proposed method can make a WTG operate steadily at any preset speed over a wide range and generate the rated power at high wind speeds. The VFESS can either absorb or release considerable energy without additional cost. In addition, the discussions on the potential prospect of KE in WTGs and the transition ways of rotational speed at high wind speeds are also investigated.

Neural network adaptive backstepping control via uncertainty compensation for PMSG-based variable-speed wind turbine: Controller design and stability analysis

This paper proposes a design scheme along with stability analysis of a new adaptive backstepping controller designed for permanent magnet synchronous generator-based wind turbine, by using artificial neural network-based uncertainty compensation. The idea is to control the rotor speed and the mechanical power generated under internal and external nonlinear parametric uncertainties. An uncertain model of permanent magnet synchronous generator is designed. Then, two artificial neural network compensators are built to compensate such uncertainties in the current loops. The stability of the closed-loop system is studied according to the Lyapunov function. Simulations of the dynamic model are performed under both variable step and random wind speeds by using the DEV-C++ software, and the results are plotted with MATLAB. Compared to the classical direct torque control technique, the obtained results show the robustness of the proposed controller despite the presence of different uncertainties.

Stabilization of permanent magnet synchronous generator-based wind turbine system via fuzzy-based sampled-data control approach

This study concerns the stabilization analysis for nonlinear permanent magnet synchronous generator (PMSG)-based wind turbine system under fuzzy-based memory sampled-data (FBMSD) control scheme. In this regard, the Takagi-Sugeno (T-S) fuzzy theory is utilized in the conversion of the proposed nonlinear model into linear-sub models and the corresponding FBMSD controller is designed. The paper introduces a suitable Lyapunov–Krasovskii functional that contains the information about the length of the sampling interval and a constant transmission delay. In order to stabilize the proposed system, sufficient conditions are derived in the form of linear matrix inequalities. As a test benchmark, the derived T-S fuzzy PMSG model is evaluated with a particular data set values and then validated with derived conditions. Besides that, the dynamical nature of system variables with respect to a blade pitch angle of the wind turbine system also discusses along with d-q axes inductance via numerical simulations. Finally, a comparison of derived conditions with the existing works is discussed to prove the less conservatism of the proposed method.

Real-time dc-link voltage control of 5-kW PMSG-based wind turbine generator through a test-rig

In this work unlike the usual grid side converter, the machine side converter is considered to control the dc-link voltage of a permanent magnet synchronous generator-based wind turbine generator. For this purpose, a discrete real-time laboratory test-rig is prepared for real-time application of the system. In the real-time test-rig, 5-kVA permanent magnet synchronous servo motor is driven by Unidrive SP variable frequency drive to emulate a standalone wind energy conversion system; GUASCH converter as a machine side converter and for implementing the designed PI controllers using pole placement technique combined with a symmetrical optimum criterion for real-time control of the dc-link voltage transient changes, Texas instrument TMS320F28069 digital signal processor discrete real-time microcontroller control card in a GUASCH board are used. Moreover, a simulation model of the system is prepared in MATLAB Simulink user-defined function blocks considering the dynamic mathematical equations of every part in the system. Achieved simulation and real-time test-rig results show that the designed dc-link voltage control of the system works properly at different transient load changes connected to the standalone WTG and dc voltage reference value changes. Moreover, the simulation results are properly validated by the real-time test-rig results and the PI controller designed using pole placement technique combined with a symmetrical optimum criterion method was ideal.

A hybrid sensorless control of PMSG wind-power generator with frequency signal injection method and extended Kalman filter

Based on the rotating high-frequency voltage-signal injection technique this paper introduces and compares two different approaches to extract the rotor position information for sensorless low speed control of direct-drive permanent magnet synchronous generator-based wind power system. One of the approaches is to extract the rotor position information from the carrier current of permanent magnet synchronous generator (PMSG) by the traditional bandpass filter. The other one is to use an extended Kalman filter algorithm. The effectiveness of the proposed sensorless low speed control is shown by numerical simulations using MATLAB/Simulink environment. The simulation results show that both control schemes provide an accurate estimate of the position of the PMSG-wind turbine and shaft speed. But extended Kalman filter algorithm improves the efficiency of the high-frequency voltage-signal injection method by eliminate the phase shift introduce by the traditional bandpass filter.

A modified sliding mode controller for a permanent magnet synchronous generator-based wind turbine system

To enhance the control and stability of the wind energy conversion system (WECS) based on direct drive permanent magnet synchronous generator (PMSG), this artefact presents a modified sliding mode control approach. A detailed time domain dynamic model of PMSG-based WECS integrated to infinite bus is also presented in terms of d-q reference frame. In order to compensate the general limitations with regard to various control strategies, a proportional integral (PI) type sliding surface-based fast sliding mode control is executed for the above. A current control strategy has been suggested for real and reactive power control keeping voltage under the desired limit. To justify the superior performance of the proposed controller in terms of robustness, reliability and accuracy compared to PI controller, the control strategy is validated through MATLAB simulation, when the system is subjected to diverse operating conditions like wind speed and system parameter variations.

A hybrid sensorless control of PMSG wind-power generator with frequency signal injection method and extended Kalman filter

Based on the rotating high-frequency voltage-signal injection technique this paper introduces and compares two different approaches to extract the rotor position information for sensorless low speed control of direct-drive permanent magnet synchronous generator-based wind power system. One of the approaches is to extract the rotor position information from the carrier current of permanent magnet synchronous generator (PMSG) by the traditional bandpass filter. The other one is to use an extended Kalman filter algorithm. The effectiveness of the proposed sensorless low speed control is shown by numerical simulations using MATLAB/Simulink environment. The simulation results show that both control schemes provide an accurate estimate of the position of the PMSG-wind turbine and shaft speed. But extended Kalman filter algorithm improves the efficiency of the high-frequency voltage-signal injection method by eliminate the phase shift introduce by the traditional bandpass filter.

A modified sliding mode controller for a permanent magnet synchronous generator-based wind turbine system

To enhance the control and stability of the wind energy conversion system (WECS) based on direct drive permanent magnet synchronous generator (PMSG), this artefact presents a modified sliding mode control approach. A detailed time domain dynamic model of PMSG-based WECS integrated to infinite bus is also presented in terms of d-q reference frame. In order to compensate the general limitations with regard to various control strategies, a proportional integral (PI) type sliding surface-based fast sliding mode control is executed for the above. A current control strategy has been suggested for real and reactive power control keeping voltage under the desired limit. To justify the superior performance of the proposed controller in terms of robustness, reliability and accuracy compared to PI controller, the control strategy is validated through MATLAB simulation, when the system is subjected to diverse operating conditions like wind speed and system parameter variations.