Synchronous Generator Based Wind Turbine Research Articles

Enhancing wind power with permanent magnet synchronous generator control strategies

AbstractDue to the substantial rise in wind power generation, the direct-drive permanent magnet synchronous generator has emerged as a leading technology for efficient variable speed operation, meeting grid demands effectively. This paper presents a comparative analysis of control strategies for permanent magnet synchronous generator based wind turbine using real variable wind speed data from a 2 MW of Tetouan wind farm in Morocco. The proposed approach is based on evaluating two primary control strategies: the adaptive fuzzy-proportional-integral controller and the conventional proportional-integral controller aimed at enhancing the wind turbine's output power. The simulation performed on MATLAB-Simulink indicates that pitch control mechanisms play a crucial role in optimizing power generation, also demonstrating its ability to achieve satisfactory performance.

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.

DC Voltage Output Control of a Hybrid Synchronous Generator-based Wind Turbine

This article discusses regulating a Wind Turbine (WT) that uses a Hybrid Excitation Synchronous Generator (HESG) to power an isolated load via a diode bridge rectifier. The HESG acts as a DC generator and supplies power to the DC load. The primary objective of the suggested control strategy is to maintain a steady DC voltage output, even when there are changes in rotor speed and/or load. The entire system is simulated and modelled in Matlab/Simulink, and the simulation results prove the effectiveness of the proposed method in delivering power to an isolated location.

Integrated Equivalent Model of Permanent Magnet Synchronous Generator Based Wind Turbine for Large-scale Offshore Wind Farm Simulation

Integrated Equivalent Model of Permanent Magnet Synchronous Generator Based Wind Turbine for Large-scale Offshore Wind Farm Simulation

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.

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.

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.

Investigations on OTC-MPPT Strategy and FRT Capability for PMSG Wind System with the Support of Optimized Wind Side Controller Based on GWO Technique

Stable operation of permanent-magnet synchronous generator-based wind turbines (PMSG-WTs) is a challenging and complicated objective. Dealing with the hard situations and complex operations of the PMSG-WTs has recently become a hot issue in modern power systems. The abilities of PMSG-WT to ride over faults and operate at maximum power point (MPP) are the most critical requirements for national grid regulations. To maintain the system's reliability, PMSG-WT should remain linked to the grid during normal and abnormal conditions. Furthermore, PMSG-WT has the potential to inject reactive power during failures. It produces active and reactive power to maintain grid voltage immediately after the fault is cleared. This research uses MATLAB/Simulink to investigate the operation at MPP during wind speed changes and FRT capability during three-phase fault of PMSG-WT to validate the support of grey wolf optimizer (GWO)-based PI controllers at the wind side converter. The findings reveal that, when PMSG-WT is exposed to a fault, active and reactive power react in a complementary manner, i.e., active power to the grid drops, and injected reactive power rises to stabilize the system. While during wind speed changes the system achieves MPP operation using an optimal torque control strategy, and the output power follows the wind variations.

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.

Frequency Limited & Weighted Model Reduction Algorithm With Error Bound: Application to Discrete-Time Doubly Fed Induction Generator Based Wind Turbines for Power System

The state-space representations grant a convenient, compact, and elegant way to examine the physical systems, e.g., induction and synchronous generator-based wind turbines, with facts readily available for stability, controllability, and observability analysis. In this article, the model order reduction of a stable doubly fed induction generator based variable-speed wind turbines model is performed with the aid of the proposed stability preserving balanced realization algorithm based on discrete frequency weights and limited frequency-interval. The frequency weighting and limited frequency-intervals-based model order reduction techniques presented by Enns’s and Wang & Zilouchian produce an unstable reduced-order model at certain frequency weights and frequency intervals, respectively. To overcome this main drawback, many researchers provided a solution to preserve the stability of the reduced-order model. However, these existing approaches also produce an unstable reduced-order model in some conditions and produce a large variation to the original system; consequently, they provide a large approximation error. The proposed approach not only ensures the stability of the reduced-order model but also provides low approximation error as compared with other existing approaches and also provides an easily calculable a priori error bound formula. The proposed work produces steady and precise outcomes in contrast to conventional reduction methods, which shows the efficacy of the proposed algorithm.

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 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.

Development of Frequency Weighted Model Reduction Algorithm with Error Bound: Application to Doubly Fed Induction Generator Based Wind Turbines for Power System

The state-space representations grant a convenient, compact, and elegant way to examine the induction and synchronous generator-based wind turbines, with facts readily available for stability, controllability, and observability analysis. The state-space models are used to look into the functionality of different wind turbine technologies to fulfill grid code requirements. This paper deals with the model order reduction of the Variable-Speed Wind Turbines model with the aid of improved stability preserving a balanced realization algorithm based on frequency weighting. The algorithm, which is in view of balanced realization based on frequency weighting, can be utilized for reducing the order of the system. Balanced realization based model design uses a full frequency spectrum to perform the model reduction. However, it is not possible practically to use the full frequency spectrum. The Variable-Speed Wind Turbines model utilized in this paper is stable and includes various input-output states. This brings a complicated state of affairs for analysis, control, and design of the full-scale system. The proposed work produces steady and precise outcomes such as in contrast to conventional reduction methods which shows the efficacy of the proposed algorithm.

New Adaptive Control Strategy for a Wind Turbine Permanent Magnet Synchronous Generator (PMSG)

Wind energy conversion systems have become a key technology to harvest wind energy worldwide. In permanent magnet synchronous generator-based wind turbine systems, the rotor position is needed for variable speed control and it uses an encoder or a speed sensor. However, these sensors lead to some obstacles, such as additional weight and cost, increased noise, complexity and reliability issues. For these reasons, the development of new sensorless control methods has become critically important for wind turbine generators. This paper aims to develop a new sensorless and adaptive control method for a surface-mounted permanent magnet synchronous generator. The proposed method includes a new model reference adaptive system, which is used to estimate the rotor position and speed as an observer. Adaptive control is implemented in the pulse-width modulated current source converter. In the conventional model reference adaptive system, the proportional-integral controller is used in the adaptation mechanism. Moreover, the proportional-integral controller is generally tuned by the trial and error method, which is tedious and inaccurate. In contrast, the proposed method is based on model predictive control which eliminates the use of speed and position sensors and also improves the performance of model reference adaptive control systems. In this paper, the proposed predictive controller is modelled in MATLAB/SIMULINK and validated experimentally on a 6-kW wind turbine generator. Test results prove the effectiveness of the control strategy in terms of energy efficiency and dynamical adaptation to the wind turbine operational conditions. The experimental results also show that the control method has good dynamic response to parameter variations and external disturbances. Therefore, the developed technique will help increase the uptake of permanent magnet synchronous generators and model predictive control methods in the wind power industry.

Overview of Subsynchronous Oscillation in Grid-connected Wind Farm

Background: Over the past few years, the subsynchronous oscillation (SSO) caused by the grid-connected wind farm had a bad influence on the stable operation of the system and has now become a bottleneck factor restricting the efficient utilization of wind power. How to mitigate and suppress the phenomenon of SSO of wind farms has become the focus of power system research. Methods: This paper first analyzes the SSO of different types of wind turbines, including squirrelcage induction generator based wind turbine (SCIG-WT), permanent magnet synchronous generator- based wind turbine (PMSG-WT), and doubly-fed induction generator based wind turbine (DFIG-WT). Then, the mechanisms of different types of SSO are proposed with the aim to better understand SSO in large-scale wind integrated power systems, and the main analytical methods suitable for studying the SSO of wind farms are summarized. Results: On the basis of results, using additional damping control suppression methods to solve SSO caused by the flexible power transmission devices and the wind turbine converter is recommended. Conclusion: The current development direction of the SSO of large-scale wind farm grid-connected systems is summarized and the current challenges and recommendations for future research and development are discussed.

Optimal tuning of proportional–integral controller using particle swarm optimization algorithm for control of permanent magnet synchronous generator based wind turbine with tip speed ratio for maximum power point tracking

This article deals with the study of the particle swarm optimization algorithm and its variants. After modeling the global system, a comparative study is carried out about the algorithms described in order to choose the best of those to be used thereafter. Then, the perturbed particle swarm optimization is presented to determine the optimal parameters of the proportional–integral controller for speed control to certify the tip speed ratio for maximum power point tracking of a wind energy conversion system. A numerical simulation is used in conjunction with the particle swarm optimization algorithm to determine the proportional–integral controller optimal parameters. From the simulations results, we observe that the proportional–integral controller designed with particle swarm optimization gives better results compared to the traditional method (proportional–integral manually) in terms of the performance index.

Assessment of proposed maximum power point tracking–unity power factor algorithms for optimum operation permanent magnet synchronous generator–based wind turbine

It is very important to select proper maximum power point tracking algorithm in order to achieve best performance and low cost for wind turbine–generator combination. A permanent magnet synchronous generator steady-state unity power factor analytical model based on a current source—equivalent circuit is provided. Validation of the identified load angle effect in current source as compared with that of the commonly used voltage source permanent magnet synchronous generator is presented. Then three new maximum power point tracking–load angle control algorithms based on current source model are presented. They all apply magnitude and frequency control techniques for Digital Signal Processor control systems. The first one presents maximum power point tracking–unity power factor applying constrained load angle control algorithm. The merits of the next two developed schemes are quickly and precisely tracking the maximum power output of the wind turbine; thus, the second and third algorithms are then characterized with linear control systems. The linearity of the second scenario is between load angle and reference speed while the third one has a load angle–torque linear relationship which shows its optimality. Finally, the controlled characteristics and implementation for the optimum case are presented for both stationary and synchronous reference frames (for vector control purposes). Simulation modeling for optimum case is provided and its results match well with the proposed predictive control algorithm.