Permanent Magnet Synchronous Generator Wind Turbine Research Articles

Deep reinforcement learning for PMSG wind turbine control via twin delayed deep deterministic policy gradient (TD3)

AbstractThis 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.

A Dynamic Equivalent Method for PMSG-WTG Based Wind Farms Considering Wind Speeds and Fault Severities

The dynamic security assessment of power systems needs to scan contingencies in a preselected set through time-domain simulations. With more and more wind power generation integrated into power systems, the complexity of simulation will increase greatly if wind farms are modeled in detail. Thus, it is critical to develop dynamic equivalent methods for wind farms. The dynamic response characteristics of permanent magnet synchronous generator-wind turbine generators (PMSG-WTGs) are not only influenced by their control strategies, but also by the operating wind speeds and the fault severities. Thus, this paper proposes a dynamic equivalent method for a PMSG-WTG based wind farm considering the wind speeds and the fault severities. Firstly, we propose a clustering method based on the operating wind speed and the terminal voltage of each PMSG-WTG at the end of the fault. Then, a single-machine equivalent method is introduced for each cluster of PMSG-WTGs. For the cluster of PMSG-WTGs with active power ramp recovery process, an equivalent model with segmented ramp rate limitation for active current is designed. In order to obtain the clustering indicators, a simulation-based iterative method is put forward. Eventually, the efficiency and accuracy of the proposed method are verified by the simulation results.

Optimized Control for PMSG Wind Turbine Systems under Unbalanced and Distorted Grid Voltage Scenarios

Wind energy is one of the fastest growing energies due to its feasible cost and environment friendly nature, where there is no emission of waste or greenhouse gases emission. Wind energy systems should be connected to the electric utility to avoid the effects of the intermittent nature of these sources. One of the main problems of the utility integration of wind turbines is the unbalanced voltage of the utility grid. Many efforts have been made to remedy the effects of the unbalanced grid voltage connected with the electric utility. This research points out the need for more accurate and robust controllers, such as those mentioned in this paper. A novel combination strategy is presented in this paper to overcome the inherent imbalance in the electric utility voltages when used in combination with a permanent magnet synchronous generator (PMSG). This novel technique is designed to adapt the positive sequence of the dq-axis of the output current from the PMSG to extract the maximum power available from a wind turbine. Meanwhile, the negative sequence component is used to improve the quality of the output current from a wind turbine. A current controller is introduced in the grid side converter to compensate for the effects of the 2nd and 6th components of the output currents. Using these controllers reduces all dominant components in the output currents from wind turbines and permits a robust tracker for the maximum power available. A detailed simulation and experimental studies are introduced in this paper to show the controller operation under different operating conditions. The simulation and experimental results from the novel proposed strategy show its superiority in fully remedying the effect of unbalanced grid voltages.

Exploring Dynamic P-Q Capability and Abnormal Operations Associated with PMSG Wind Turbines

With the proliferation of large-scale grid-connected wind farms, subsynchronous oscillation (SSO) incidents associated with Type-4 wind turbines (WTs) with a permanent magnet synchronous generator (PMSG) have occurred frequently. These incidents have caused severe reliability risks to the power grid. Conventionally, P-Q capability charts are utilized to ensure the safety operating region of a synchronous generator. However, a PMSG WT exhibits completely different and dynamic P-Q capability characteristics due to the difference in energy conversion technique and several critical factors related to the WT power converters. This paper presents a comprehensive dynamic P-Q capability study of a PMSG WT with sufficient and accurate considerations of the WT control and operation in the dq reference frame, its power converter constraints, and grid dynamics. Models of a PMSG WT are first developed based on its control principle in the dq reference frame. Then, algorithms for obtaining the P-Q capability charts of the WT are developed with the considerations of complete WT constraints in different aspects. The study analyzes the root cause of many abnormal operations of grid-connected PMSG WTs, reported in the literature, from the dynamic P-Q capability perspectives. The proposed study is verified via an electromagnetic transient (EMT) model of a grid-connected Type-4 WT.

An MPC based active and reactive power coordinated control strategy of PMSG wind turbines to enhance the support capability

As wind turbines are constantly replacing traditional units, it is becoming a consensus that wind turbines should participate in the grid support that was only responsible by traditional units in the past. In order to enhance the grid support capabilities (including active power support and reactive power support) of permanent magnet synchronous generator (PMSG) based wind turbines, this paper constructs an active and reactive power coordinated control strategy. Compared with the current active and reactive power coordinated control strategy of PMSG wind turbines, the method of the proposed one innovatively considers the climbing coordinated restriction between active and reactive power, flexible prioritization arrangement between active and reactive power, the accurate amplitude and climbing constraints of grid-side converters’ output voltage, and the model predictive control (MPC) technique. The simulation results verify that the proposed power control strategy can make PMSG wind turbines achieve excellent power output performance and thus better meet the requirements of power grid support.

A Model Independent Predictive Control of PMSG Wind Turbine Systems with a New Mechanism to Update Variables

Permanent magnet synchronous generator (PMSG) wind power system with full power rating converter configuration is especially suitable for wind energy applications. Direct model predictive control (DMPC) has led to more possibilities in terms of choice because of its straightforward concept for PMSG wind turbine systems in high-power off-shore wind farms. However, due to complete dependence on the model knowledge, parameter mismatches will seriously deteriorate the system control performances. This work presents a model/parameter-independent predictive control method with a novel mechanism to update current/power variations online. The proposed method makes use of only two measurements from the former intervals and the selected control vectors to estimate all variations of the candidate vectors in the present interval. Benefiting from this updating mechanism, the proposed method is completely independent of the model parameters in the state prediction. However, it still has a very low calculating requirement and smooth current/power variation waveforms. The proposed method is compared with classical DMPC. The results validate that the proposed solution outperforms the classical DMPC with model deviations, with considerably improved robustness.

Sliding mode pulse‐width modulation of five‐leg converter for grid‐connected permanent magnet synchronous generator wind turbine

SummaryThis paper presents sliding mode pulse‐width modulation (SMPWM) for current‐controlled five‐leg converter (FLC) in wind energy system. The proposed topology substitutes at once two three‐phase converters, classified as back‐to‐back (BTB), by sharing one leg between the permanent magnet synchronous generator (PMSG) and power grid. To overcome the coupling of the two sides, the control of common leg is introduced. SMPWM methodology is designed using system dynamic model and surface decoupling approach to make system tracking desired references. The reference currents are selected to perform control requirements of PMSG wind turbine. The phase currents are controlled simultaneously during normal operation and in the event of unbalanced grid voltages. Different operating conditions are tested under wind variations including a turbulence component. The main objectives are to achieve balanced and sinusoidal currents, as well as smooth active and reactive powers injected into the grid. Simulation results show that FLC can act as BTB converters and demonstrate the effectiveness of the proposed control scheme.

Finite-time fault detection and reconstruction of permanent magnet synchronous generation wind turbine via sliding mode observer

In this study, a method for fault detection of a permanent magnet synchronous generator (PMSG) wind turbine is proposed. The dynamic model of the wind energy conversion system is simulated and the system’s fault is diagnosed using a proposed terminal sliding mode observer (TSMO). The nonlinear state-space equations of the closed-loop wind turbine are derived, which include a robust adaptive controller that is implemented for maximum power capture and a PI controller that is designed for pitch angle control. Then, utilising a new approach, a TSMO is designed for estimating the states and faults in a finite time. The stability and convergence of the states and fault estimation error are investigated via the Lyapunov stability theory. A PMSG wind turbine is simulated and using TSMO the states are estimated and a blade imbalance fault (BIF) fault is detected. The state and fault estimation errors converge to zero in a finite time.

Robust Nonlinear Adaptive Control for Power Quality Enhancement of PMSG Wind Turbine: Experimental Control Validation

Due to the intense penetration of wind energy into the power grid, grid quality and stability have become a crucial necessity in this type of power generation. It is in this context that this article has just designed an Adaptive Nonlinear Control strategy applied to the Permanent Magnet Synchronous Generator (PMSG) of 1.5 MW power, in order to generate good quality and cleanly usable energy. Interestingly, this robust control algorithm mainly uses the Lyapunov stability theory, which ensures the stability of the Wind Energy Conversion System (WECS), and therefore offers excellent results in the presence of system parametric uncertainties and changes in the elements of the external environment. To this end, the methodology followed in this in-depth study focuses on the application of the Adaptive Backstepping Control algorithm for WECS by exploiting the MATLAB/Simulink toolbox. The theoretical study and simulation of the WECS was supported by the Processor-in-the-Loop (PIL) implantation of the control in the dSPACE DS1104 embedded board to approve the effect of the control in terms of robustness against different wind profiles and parametric changes. ST-LINK communication is used to connect the embedded board and the host computer. The results obtained revealed a fast response of the different signals, a practically low ripple rate of the order of 0.1% and minor overshoots for the different electrical quantities. Operation with a unity power factor is well ensured via this control strategy. Therefore, the adaptive control applied to the WECS has verified the high performance offered and benefits from additional robustness properties.

Comparative Performance of DFIG and PMSG Wind Turbines during Transient State in Weak and Strong Grid Conditions Considering Series Dynamic Braking Resistor

The recently stipulated grid codes require wind generators to re-initiate normal power production after grid voltage sag. This paper presents a comparative performance of two commonly employed variable speed wind turbines in today’s electricity market, the doubly fed induction generator (DFIG) and the permanent magnet synchronous generator (PMSG) wind turbines. The evaluation of both wind turbines was performed for weak, normal and strong grids, considering the same machine ratings of the wind turbines. Because of the critical situations of the wind turbines during faulty conditions in the weak grids, an analysis was done considering the use of effective series dynamic braking resistor (SDBR) for both wind turbines. The grid voltage variable was employed as the signal for switching the SDBR in both wind turbines during transient state. Additionally, an overvoltage protection system was considered for both wind turbines using the DC chopper in the DC-link excitation circuitry of both wind turbines. Furthermore, a combination of the SDBR over-voltage protection scheme (OVPS) was employed in both wind turbines at weak grid condition in order to improve the performance of the variable speed wind turbines and keep the operation of the power converters within their permissible limits. Furthermore, the performance of the DFIG and PMSG wind turbines in weak grids were further investigated, considering the combination of 75% and 50% effectively sized SDBR and OVPS. It was observed that, even with a 50% reduction in SDBR or OVPS, the performance of both wind turbines is still satisfactory with faulty conditions. Therefore, it is recommended to use a combination of the SDBR and OVPS with DFIG- or PMSG-based variable speed wind turbines to achieve a superior fault ride through performance, especially in weak grids. The system performance was evaluated using the power system computer design and electromagnetic transient including DC (PSCAD/EMTDC) platform.

Implementation and Validation for Multitasks of a Cost-Effective Scheme Based on ESS and Braking Resistors in PMSG Wind Turbine Systems

This study deals with fault ride-through (FRT) capability and output power fluctuation suppression of wind turbine systems (WTS) having PMSG (permanent-magnet synchronous generator) for mitigating grid frequency variation and voltage flicker in the distribution system. The coordinated control of a cost-effective scheme based on energy storage supercapacitors (ESSs) and braking resistors (BR) is introduced to perform the multiple tasks of the WTS. In this hybrid scheme, the ESSs are initially used to absorb the fluctuated power component with the constraints of their ratings during the grid faults and wind speed variation conditions prior to the activation of the BRs when the ESSs cannot fully consume the mismatched power between the PMSG and grid during severe grid faults. With the additional BRs, the capacity of the costly ESSs is remarkably reduced, while the performance of the fault ride-through capability and power smoothening for the WTS are still kept satisfactory and in compliance with the requirements of advanced grid codes. Detailed experimental implementation and its results for a down-scaled prototype in a laboratory are shown to verify the effectiveness of the introduced scheme along with the simulation results with the high-power rating WTS.

A Fault Ride-Through Technique for PMSG wind turbines using Superconducting Magnetic Energy Storage (SMES) under Grid voltage sag conditions

Wind power penetration is growing, posing considerable technological challenges for developing electrical grid systems. Gearless permanent magnet synchronous generator (PMSG) wind energy conversion systems (WECS) are becoming more popular. On the flip side, they are susceptible to grid failures. The use of Superconducting Magnetic Energy Storage (SMES) to enhance fault ride-through in PMSG wind turbines is investigated. Per the current Grid code trends, WECS are not to be disconnected from the grid; rather, they should provide reactive power support during such situations. This work incorporates machine and grid side converters to manage reactive, active power and DC-link voltage during grid failures. To improves system performance, lessen voltage dips at the point of common coupling (PCC), provide reactive power support and reduce the transient length, a DC-link capacitor is used with SMES. SMES reserve energy capacity is necessary for FRT operation when the wind turbine's inertial response range is insufficient. Finally, a 1.5 MW PMSG-based WTG with SMES is developed. The Pre-fault, fault-period, and post-fault performance are all assessed. They confirm the system's efficiency, speed, and stability.

Comparative analysis of maximum power extraction and control methods between PMSG and PMVG-based wind turbine systems

The objective of this study is to compare, analyze and evaluate the performance between permanent magnet synchronous generator (PMSG) and permanent magnet vernier generator (PMVG)-based wind turbine systems (WTSs) using maximum power point tracking (MPPT) control technology. To do this, first, the dynamical model of the PMSG and PMVG-based WTS is constructed. Next, the traditional and improved optimum torque control-based MPPT schemes are employed to validate the dynamical performance between the PMSG and PMVG-based WTS. And then, the generator current augmentation-based optimum torque control strategy is proposed to extract the maximum output power from various wind conditions. This method can effectively reduce the influence of the moment of inertia in WTS and ensure the transient performance of the MPPT scheme. Further, an analytical model of 5-kW PMSG and PMVG-based WTS is presented to provide a fair comparison with MPPT schemes and outline their respective advantages and disadvantages. Finally, the comparative simulation and experimental results demonstrate the feasibility of employing PMSG and PMVG in WTS.

PMSG Wind Turbine Based Current Fed Three Phase Inverter with Model Predictive Control

Design of an improved Permanent Magnet Synchronous Generator (PMSG) wind turbine power based Current Fed Inverter (CFI) using Model Predictive Controller (MPC) is proposed in this paper. Optimum torque control is proposed in wind energy conversion system, MPC is used to adjust the dynamic response time based on the application need. This model deals with torque control strategy of PMSG in the machine side controller. Impact of normal mode of operation by the copper losses and torque ripples are minimized by maximizing the average torque. Synthetization of adequate stator phase current are obtained naturally. Uncertainty of the steady state errors of the plant and parameter error are rectified in the system model. The designed CFI with MPC was implemented using medium range wind turbine in MATLAB /Simulink. The simulation output shows the better efficiency in over modulation region by the proposed CFI with controller. Constant switching frequency is maintained and efficient required dynamic response (DR) value is attained.

Design of Decentralized Hybrid Microgrid Integrating Multiple Renewable Energy Sources with Power Quality Improvement

Due to the energy crisis and exhaustion in the amount of fossil fuels left, there is an urge to increase the penetration of renewables in the grid. This paper deals with the design and control of a hybrid microgrid (HMG) in the presence of variable renewable energy sources. The DC sub-grid consists of a permanent magnet synchronous generator (PMSG) wind turbine, solar PV array with a perturb-and-observe (P&O) MPPT algorithm, boost converter, and battery energy storage system (BESS) with DC loads. The AC sub-grid consists of a PMSG wind turbine and a fuel cell with an inverter circuit synchronized to the grid to meet its load demand. A bidirectional interlinking converter (IC) connects the AC sub-grid and DC sub-grid, which facilitates power exchange between them. The decentralized control of converters allows all the renewables to operate in coordination independently without communication between them. The proposed control algorithm of the IC enables it to act as an active power filter in addition to the power exchange operation. The active power filtering feature of the IC helps to retain the power quality of the microgrid as per IEEE 519 standards by providing reactive power support and reducing the harmonic levels to less than 5%. The HMG with the proposed algorithm can operate in both grid-connected and islanded modes. While operating in grid-connected mode, power exchange between DC and AC sub-grids takes place and all the load demands are met. If it is in islanded mode, a diesel generator supports the AC sub-grid to meet the critical load demands and the BESS supports the DC microgrid. The proposed model is designed and simulated using MATLAB-SIMULINK and its results are analyzed. The efficacy of the proposed control is highlighted by comparing it with the existing controls and testing the HMG for load variations.

Improving the Performance of PMSG Wind Turbines During Grid Fault Considering Different Strategies of Fault Current Limiters

The wind energy conversion technology of a Permanent Magnet Synchronous Generator (PMSG) is very promising in renewable power generation. However, the performance of the grid-connected PMSGs is greatly affected by grid disturbances because their stator windings are interfaced with the grid directly. There are different Fault Current Limiter (FCL) topologies that are capable of improving the Fault Ride Through (FRT) capability of PMSG wind turbines during short circuit faults. This study investigates three types of FCLs connected to the grid side of the PMSG wind turbine: Series Dynamic Braking Resistor (SDBR), traditional Bridge Fault Current Limiter (BFCL), and Capacitive Bridge Fault Current Limiter (CBFCL). Complete modeling of FCLs was derived in order to understand their behaviors accurately during normal conditions and fault periods. The performance of the three FCLs in the PMSG wind turbine was analyzed and compared using a severe three-phase to ground fault at the terminal of the PMSG wind turbine in Power System Computer Design and Electromagnetic Transient Including DC (PSCAD/EMTDC) platform. The same conditions of operation were used in investigating the various FCL strategies in the PMSG wind turbine considered in this study during grid fault for effective comparison.

Integral-type terminal sliding mode control approach for wind energy conversion system with uncertainties

This paper investigates a robust controller for the wind energy conversion system (WECS) based on permanent magnet synchronous generator (PMSG) with parametric uncertainties. A robust nonlinear controller is developed for PMSG wind turbine (PMSG-WT) using integral-type terminal sliding mode control (ITTSMC) to ensure maximum aerodynamic power for the system and enhance its performance. The proposed control technique: (i) ensures the convergence of the state variables of the system in finite-time; (ii) reduces the chattering problem in the sliding mode control (SMC); (iii) increases the robustness of the PMSG-WT in the presence of uncertainties. The simulation results for the proposed controller efficiency are performed using the MATLAB/Simulink environment. Besides, a comparative study considers the performance of the suggested control technique with backstepping and SMC techniques. The performance of the ITTSMC method is checked using different situations such as varying wind conditions, parametric uncertainties, and random noise.

Overall fuzzy logic control strategy of direct driven PMSG wind turbine connected to grid

The fuzzy logic strategies reported in the literature about the control of direct drive permanent magnet synchronous generator (PMSG) connected to grid are limited in terms of inclusiveness and efficiency. So an overall control based on fuzzy logic and anti-windup compensation is proposed in this paper. Aiming at the inadequate of hill climb search (HCS) MPPT with fixed step size, the fuzzy logic is introduced in the stage of "generating rotor speed reference" to overcome the oscillations and slowness in traditional method. PI controllers are replaced by anti-windup fuzzy logic controllers in the "machine side control" stage and in "grid side control" stage to pertinently regulate the reference parameters. Then comparison tests with classical methods are implemented under varying climatic conditions. The results obtained demonstrate that the developed control is superior to other methods in response time (less than 4.528E-04 s), precision (an overshoot about 0.41%) and quality of produced energy (efficiency is 91%). The study verifying the feasibility and effectiveness of this algorithm in PMSG wind turbine connected to grid.

A fixed-time fractional-order sliding mode control strategy for power quality enhancement of PMSG wind turbine

This paper proposes a fixed-time fractional-order sliding mode controller (FTFOSMC) for the permanent magnet synchronous generator (PMSG) wind turbine to enhance the power quality. The FTFOSMC is implemented in the rotor side converter (RSC) and the grid side converter (GSC) to stabilize the PMSG wind turbine within an upper limited convergence time and to improve the dynamic performances. The fractional-order calculus is taken to devise fractional-order controller and the expression of the FTFOSMC is a continuous description, which can better weaken the chattering phenomenon of conventional SMC. Meanwhile, fixed-time stability is adopted to ensure the stabilization of the PMSG wind turbine within an upper limited convergence time irrelated with the initial states. The detailed proof is presented to validate that the proposed FTFOSMC can ensure the PMSG wind turbine stable and estimate the upper limited convergence time through Lyapunov function. Finally, several cases, including peak power tracking and reactive power control, variable wind speeds, grid voltage disturbances and experimental verification, are studied to show the effectiveness, robustness and superiority of the FTFOSMC than the PI control. Simulation and experimental results show that the FTFOSMC can achieve superior dynamic performances than the PI control with shorter convergence time, less vibration, higher tracking accuracy and stronger robustness, thus improving power quality of the PMSG wind turbine.

Educational tool for analysis of proportional integral and fractional order proportional integral controlled quadratic boost converter system using MATLAB/simulink

This paper displays an simple method for identification of controller for wind based Quadratic Boost Converter Inverter system. India, being the fourth largest wind power generator has attracted numerous researchers towards the improvement of wind energy conversion system. This paper also presents improved controller techniques for a Permanent Magnet Synchronous Generator (PMSG) coupled with Cascaded Quadratic Boost Converter (QBC) and Space Vector Modulation Inverter (SVMI). The digital simulation and execution of PMSG based wind turbine along with QBC and SVM Inverter is presented in a closed loop system. The performance of closed loop system is realized using Proportional Integral (PI) and Fractional Order Proportional Integral (FOPI) controllers. Initially, the AC power from PMSG wind turbine is rectified to DC using rectifier circuit. The DC power from the bridge rectifier is then boosted to the required level using quadratic boost converter. The output from QBC is then given to the SVM inverter. The closed loop investigations are carried with PI and FOPI controllers. The simulation results of both PI and FOPI controlled QBC are compared. The outcome of FOPI controller represents that the steady state error and settling time are reduced when compared to PI controlled closed loop Quadratic Boost Converter. The overall Matlab/simulink model is applied to undergraduate/postgraduate course as a educational tool and assessed thoroughly.