Speed Permanent Magnet Synchronous Generator Research Articles

Sliding Mode Control for PMSG-based Wind Power System

Variable structure control has proven particularly suitable to variable speed wind energy conversion system control, being easy to implement by the already existing electronics. Its main drawback is an increase of mechanical stress due to chattering, which can however be alleviated by various methods. This paper proposes a sliding mode approach for tracking the energetic optimum of a variable speed permanent magnet synchronous generator PMSG. The sliding surface is systematically derived from imposing a desired reduced-order dynamics and allows the turbine operation more or less close to the optimal regimes characteristic, according to an imposed trade-off between the torque (control input) ripple and the optimum tracking. In this way, by torque controlling the generator, a multipurpose (energy-reliability) optimization is actually achieved.

Fault Ride-Through Enhancement of PMSG Wind Turbines With DC Microgrids Using Resistive-Type SFCL

Integrating permanent magnet synchronous generator (PMSG) wind turbines with DC microgrids have attracted a great attention due to the inherent merits of DC systems. However, under the fault conditions, the excessive energy during fault will be reflected on PMSG rotating parts causing overspeed, mechanical stresses, and fast aging. Also, large fault currents will force generator-side converter to disconnect making it not complied with grid codes. Accordingly, this paper aims to apply superconducting fault current limiter (SFCL) to enhance the performance of PMSG wind turbines with DC microgrids under the fault conditions. PSCAD/EMTDC software is used to build the system under study that includes PMSG, controlled AC/DC converter, SFCL, and DC bus. The behavior of SFCL in enhancing the DC output of the converter is first studied. Then, the impact of using SFCL on the speed, torque, and output current of PMSG is investigated and discussed. Finally, the suitable current limiting resistance is adopted considering DC output as well as PMSG speed.

Student-tailored final year project on microcontroller-based hardware-in-the-loop speed control of a wind generator

Student-supervisor cooperation was carried out to design the inter-subject final year project reported in this paper. According to the student feedback, this approach allowed gathering his main interests – vector control, microcontroller programming and wind power generation – together, therefore reinforcing his motivation towards his final year project and making him feel particularly responsible for its outcome. Microcontroller-based hardware-in-the-loop emulation made possible to combine the three afore-cited student interests. In this context, the virtual prototype of a current-controlled wind turbine-driven 2-MW permanent-magnet synchronous generator is presented, along with the pseudo-code corresponding to the permanent-magnet synchronous generator speed control algorithm programmed in an 8-bit microcontroller. In addition, tuning formulas are derived for the digital integral-proportional controllers commanding both the permanent-magnet synchronous generator current and speed. Detailed descriptions are provided in order to guarantee reproducibility. Implementation of the hardware-in-the-loop rig is also tackled, supported by illustrative results obtained when running it. The developed hardware-in-the-loop rig is considered suitable for laboratory practices of subjects like digital control and microcontroller programming.

ANN Control Based Variable Speed PMSG-Based Wind Energy Conversion System

This paper presents a comparative analysis of three control algorithms for a wind turbine generator using a variable speed permanent magnet synchronous generator (PMSG). The design methodologies of the conventional PI based controller, the Taylor series expansion linear approximation based (TSLA-based) controller and the feedback linearization based (FL-based) nonlinear controller are provided. The objective is to keep the wind turbine operating at normal speed of the rotor at maximum power extraction (MPPT control), while insuring the power extracting from the turbine to the generator, regardless of the wind speed. The controller gains of the nonlinear controller are extended with Artificial Intelligence controller approach. The results show a better control performance for the ANN controller. This performance of Ann controller can be characterized by fast and smooth transient responses as well as a zero steady state error and reference tracking quality.

Power electronic interface with de‐coupled control for wind‐driven PMSG feeding utility grid and DC load

A wind energy conversion system employing dq control has been proposed for extracting maximum power from a wind-driven permanent magnet synchronous generator (PMSG) and feeding it to a three-phase utility grid. The controller consists of a diode bridge rectifier, a dc–dc boost converter and a voltage source inverter (VSI). The grid synchronisation is achieved by controlling the VSI at the grid side. Besides supplying power to the ac grid, the proposed scheme also feeds a local dc load, as the dc link voltage is maintained constant. To evaluate the performance of proposed scheme, MATLAB/Simulink based model is tested under varying wind speeds. A proportional–integral controller is used for varying the duty ratio of the dc–dc converter to maintain the output dc voltage constant. The decoupled control algorithm for independent control of real and reactive power fed to the grid is implemented using dSPACE DS1103 controller. A steady-state analysis has been developed for predicting the value of duty cycle as well as the reference current for maximum power point tracking at a given wind velocity or rotor speed of PMSG. Experiments have been carried out on a 48 V, 750 W, 500 rpm PMSG and the test results are furnished to validate the developed scheme.

Instantaneous power control of a high speed permanent magnet synchronous generator based on a sliding mode observer and a phase locked loop

ABSTRACTThis paper proposes an instantaneous power control method for high speed permanent magnet synchronous generators (PMSG), to realize the decoupled control of active power and reactive power, through vector control based on a sliding mode observer (SMO), and a phase locked loop (PLL). Consequently, the high speed PMSG has a high internal power factor, to ensure efficient operation. Vector control and accurate estimation of the instantaneous power require an accurate estimate of the rotor position. The SMO is able to estimate the back electromotive force (EMF). The rotor position and speed can be obtained using a combination of the PLL technique and the phase compensation method. This method has the advantages of robust operation, and being resistant to noise when estimating the position of the rotor. Using instantaneous power theory, the relationship between the output active power, reactive power, and stator current of the PMSG is deduced, and the power constraint condition is analysed for operation at the unit internal power factor. Finally, the accuracy of the rotor position detection, the instantaneous power detection, and the control methods are verified using simulations and experiments.

Modeling, control and stability analysis of grid connected PMSG based wind turbine assisted with diode rectifier and boost converter

Permanent magnet synchronous generator (PMSG) based wind turbines (WTs) are widely used as grid connected energy sources. Usually, a PMSG based wind energy system is connected to the grid via machine side and grid side converters. From the machine side converter point of view, there are two types of PMSG-based WTs: PMSG with back-to-back voltage source converters, and PMSG assisted with diode rectifier and boost converter. Since most of the research works regarding the PMSG-based WTs are devoted to the former type, this paper deals with the elaborated controller design and stability analysis of the grid connected PMSG based WT assisted with diode bridge rectifier and boost converter. Hence, the linearized average dynamic model of the combined system comprising PMSG, diode rectifier and boost converter is presented. Based on the linearized model, the relation between the PMSG electromagnetic torque and boost converter current is extracted, and then system’s control-loops are developed. Next, small signal stability of the full system comprising PMSG, boost-diode rectifier, dc-link capacitor, GSC, and corresponding controllers is presented and then impact of PMSG speed controller on the stability of the system is examined theoretically and by time domain simulations.

Resilient and Robust Control of Time-Delay Wind Energy Conversion Systems

Wind energy is the fastest growing and the most promising renewable energy resource. High efficiency and reliability are required for wind energy conversion systems (WECSs) to be competitive within the energy market. Difficulties in achieving the maximum level of efficiency in power extraction from the available wind energy resources warrant the collective attention of control and power system engineers. A strong movement toward sustainable energy resources and advances in control system methodologies make previously unattainable levels of efficiency possible. In this paper, we design a general resilient and robust control framework for a time-delay variable speed permanent magnet synchronous generator (PMSG)-based WECS. A linear matrix inequality-based control approach is developed to accommodate the unstructured model uncertainties, L2 type of external disturbances, and time delays in input and state feedback variables. Computer simulation results have shown the efficacy of the proposed approach of achieving asymptotic stability and H∞ performance objectives.

Power Smoothening of Grid Connected Direct- Driven Permanent Magnet Synchronous Generator (PMSG) Wind Turbines

Objectives: The main objective of this paper is smoothening of the power fluctuation of a variable speed PMSG wind generator with the help of Energy Capacitor System (ECS). ECS consists of a voltage source inverter, dc-dc converter and an ultra-capacitor bank including their control strategies. Methods/Analysis: In this paper two back-to-back voltage source Insulated Gate Biopolar Transistor (IGBT) converters controlled through highly efficient variable frequency drive control method is considered. By using this method, efficiency of wind farm can be improved and voltage regulation for interconnecting the wind farm with grid can be achieved. Findings: Recent application of power electronic devices and scaling up of MegaWatt (MW) wind turbines, Low-speed high torque Permanent Magnet Synchronous Generator (PMSG) has become the ultimate choice for wind power extraction. At present, a commercial PMSG based wind generator primarily makes use of a rectifier followed by an IGBT converter. Novelty /Improvement: The real power reference for ECS is generated accurately. Simulation is carried out through MATLAB/SIMULINK.

Damping tie-line power oscillations by modulation feedback of wind generators

This paper uses the power modulation capability of wind generators for damping tie-line power oscillations. The type of wind generator investigated is the permanent magnet synchronous generator (PMSG) connected to the power grid through a dc link. First, the paper develops a small-signal aggregate model for the wind generator. Subsequently, three modulation signals are investigated in order to provide effective power modulation: the PMSG speed reference, the rotor blade pitch angle and the dc link voltage. The latter is a novel approach that utilizes the energy stored in the dc link capacitors in order to modulate the power injected into the grid. The paper investigates the relation between the wind turbine and PMSG dynamics and the ability of each modulation loop to provide effective damping. A design method of the feedback loops based on the damping torque concept is demonstrated in the paper. Analytical results on a two-area power system show that wind generation can enhance the system dynamic stability by damping tie-line power oscillations. The analytical results are verified through time-domain simulations of a detailed 3-phase model of the system. The proposed dc link voltage modulation is shown to be a very effective means to provide power modulation in dynamic conditions.

Application of nonlinear predictive control for charging the battery using wind energy with permanent magnet synchronous generator

Wind energy is an important renewable source which is used for power generation for a stand-alone as well as grid connected applications. In many remote areas, loads are usually connected away from the grid. In such cases, isolated wind energy systems can be considered as an effective way to provide continuous power to electrical loads.In this paper, a robust nonlinear predictive control (NLPC) for an isolated wind energy conversion system is implemented using a variable speed permanent magnet synchronous generator (PMSG) with pulse with modulation (PWM) rectifier connect to a battery. The turbine is employed with Optimal Torque control (OTC) to achieve a maximum level of wind power extraction.The main of control is to adjust the rectifier voltage amplitude in order to charge battery and this despite the presence of disturbance which manifests in the variation of wind speed and load changes varying. This control it has-been experimentally Implemented using Dspace1104 hardware driving in real-time the studied system.Practical and simulation results show that the NLPC imposes the voltage under wind conditions. The controller shows a good performance during dynamic and steady state condition.

영구자석형 풍력-디젤-BESS 복합발전시스템 모델링 및 운전제어 알고리즘에 관한 연구

Nowadays high-cost energy storage system using flywheel or secondary battery is applying to hybrid generation system with WT(Wind Turbine) and diesel generator in island areas for stable operation. This paper proposes an operating algorithm and modeling method of the hybrid generation system that can operate for variable wind speed and load, which is composed of energy storage system, variable-speed PMSG(Permanent Magnet Synchronous Generator) WT and diesel generator applied in island areas. Initially, the operating algorithm was proposed for frequency and voltage to be maintained within the proper ranges for load and wind speed changes. Also, the modeling method is proposed for variable speed PMSG WT, diesel generator and BESS(Battery Energy Storage System). The proposed operating algorithm and modeling method were applied to a typical island area. The frequency and voltage was kept within the permissible ranges and the proposed method was proven to be appropriate through simulations.

Stabilization of a Fixed Speed IG Based Wind Farm using Variable Speed PMSG

To optimize the output power and reduce the frequency fluctuation in conventional fixed speed Induction Generator (IG) based wind farm, various controlling devices are used. But, this paper proposes that Permanent Magnet Synchronous Generator (PMSG) can work both as a power producing device and as a controlling device for IG. In this paper a more practical case has been considered where a wind farm is operated with a set of Synchronous Generators (SG). Thermal, Hydro and Nuclear Governors have been used for SGs. Wind farm has a capacity of 20% of the total SG’s capacity. Both two-level and three-level converter-inverter based PMSG have been considered. Comparative results between IG and IG with PMSG are shown. Simulation results prove the effectiveness of the proposed system. Simulations have been carried out by using the laboratory standard power system software package, PSCAD/EMTDC.

Modeling and Control of Standalone Direct-Driven PMSG WECS for Grid Compatibility at Varying Wind Speeds

Wind energy is one of the most available and exploitable forms of renewable energy. Variable speed PMSG based Wind Energy Conversion System (WECS) offers many advantages compared to the fixed speed squirrel cage induction generators such as improved stator output operation at better power factor, no maintenance cost for gear box (as it is direct-driven) reduction in weight and losses, higher efficiency and ability to run at low speeds. The elimination of the gear box and brushes can enhance the efficiency of wind turbine by 10%. In this paper a Permanent Magnet Synchronous Generator (PMSG) is modeled whose stator is connected to the constant single phase load (in place of grid) through AC/DC thyristors based rectifier followed by capacitor (dc-link) and DC/DC converter control. Overall arrangement provides constant output to connected load if applied with proper controlling techniques. Hence this proposed wind generation system design can be extended for grid connection also via DC/AC inverter control. Results are simulated and verified in MATLAB/Simulink platform at constant rated (12m/s) and varying (stepped) wind speed for smooth and constant output voltage. DOI: http://dx.doi.org/10.11591/telkomnika.v13i3.7097

Thermal Modeling of PMSG Generator for Gas Turbine Applications

Objective: A customized high speed Permanent Magnet Synchronous Generator (PMSG) is designed for military applications. Thermal analysis is essential to improve the system utility during operating conditions, prevent overheating, insulation breakdown and demagnetization of magnets. Method: A thermal network model is proposed to analyze and estimate the temperature rise of the customized high speed, six phase PMSG for its design specifications. The detailed thermal model is analyzed and the thermal resistance values are obtained. The simplified model is obtained considering significant sections of the machine where the losses cause rise in temperature. Results: The thermal resistances in the thermal model are calculated based on the dimensions of the customized PMSG. The temperatures variations in the significant parts of the machine are calculated. Conclusion: The thermal values estimated are within the thermal limits for the selected class of insulation and design specifications. Keywords: High Speed, Six Phase Permanent Magnet Synchronous Generator Nomenclature, Thermal Analysis

Voltage stability enhancement using an adaptive hysteresis controlled variable speed wind turbine driven EESG with MPPT

This paper investigates the enhancement in voltage stability achieved while connecting a variable speed wind turbine (VSWT) driven electrically excited synchronous generator (EESG) into power systems. The wind energy conversion system (WECS) uses an AC-DC-AC converter system with an uncontrolled rectifier, maximum power point tracking (MPPT) controlled dc-dc boost converter and adaptive hysteresis controlled voltage source converter (VSC). The MPPT controller senses the rectified voltage (VDC) and traces the maximum power point to effectively maximize the output power. With MPPT and adaptive hysteresis band current control in VSC, the DC link voltage is maintained constant under variable wind speeds and transient grid currents.The effectiveness of the proposed WECS in enhancing voltage stability is analysed on a standard IEEE 5 bus system, which includes examining the voltage magnitude, voltage collapse and reactive power injected by the systems. Simulation results show that the proposed WECS has the potential to improve the long-term voltage stability of the grid by injecting reactive power. The performance of this scheme is compared with a fixed speed squirrel cage induction generator (SCIG), a variable speed doubly-fed induction generator (DFIG) and a variable speed permanent magnet synchronous generator (PMSG).

Thermoanalysis of the permanent magnet rotor of the microturbine generator

To evaluate the rotor temperature field of a high speed permanent magnet synchronous generator (PMSG), an electromagnetic-eddy current-thermal coupled field model is constructed using 2D Time-stepping Finite-Element-Method (FEM). In the model, the electromagnetic field and the temperature field have the same meshed grids to make a node-to- node data transmission and are solved independently. The data transmission ensures the coupling of the fields and the solve order of these fields is controlled by an external program. Temperature-dependent parameters, for example conductivity, can be set in the model. Windage loss of the rotor calculated by empirical formulas is loaded to the temperature field. Distribution of the rotor temperature is obtained by a calculation example of a 100 kW, 45000 r/min microturbine generator. Experimental data are used to show the validity of the proposed model which is helpful to the thermal design of the high speed PM generator.

Fault Detection and Control loop reconfiguration for WECS with PMSG speed sensor fault

This paper describes a fault tolerant controller (FTC) design to enhance the wind energy conversion system (WECS) with Permanent Magnet Synchronous Generator (PMSG) robustness to mechanical rotor speed sensor failure. This proposed sensor FTC strategy is based on the combination of the actual sensor and an adaptive Luenberger observer with a decision-making unit, which detects whether the mechanical sensor is faulty and selects the most accurate generator rotor speed and position for the Indirect Field Oriented control (IFOC) loops. Extensive simulation study shows that the proposed sensor FTC approach can efficiently detect the generator speed sensor fault and tolerate this type of fault, and so offers a simple configuration with a satisfactory accurate reference-rotor-speed tracking requirement for maximum power extraction.

Dynamic Response of a Stand Alone DC Side Wind Energy Conversion System with Battery Energy Storage

The study concerns particularly the DC side of the wind system, the continuity of the AC one being already studied in [1]. Then, this work elaborates an analysis of the DC components, particularly the system conversion and storage of the wind system conversion. Indeed, the battery is a storage buffer essential in our case for isolated network. We emphasize its importance by evaluating its various features. The AC study concerned the analysis and simulation of a low speed Permanent Magnet Synchronous Generator (PMSG) driven by a vertical wind turbine through a Pulse-Width Modulation (PWM) voltage inverter.Renewable resources are in constant fluctuation. Therefore, in order to maximize the efficiency of the renewable energy system it is necessary to track the maximum power point of the input source. In this system, the maximizing is assured while considering the optimal power curve as load characteristic, with the knowledge of the turbine characteristic Cp (λ).The study was accomplished on MATLAB/Simulink and Script platforms.

Control methods for PWM rectifier cooperating with variable speed PM generator

Abstract The paper deals with cooperation between pulse width modulation (PWM) rectifier and variable speed synchronous generator which is applied especially in small water or wind plants. In such applications, the synchronous generator, which is usually permanent magnet (PM) generator, rotates at a variable speed which depends on water or wind energy. Therefore, this energy should be converted to the parameters of the three-phase power grid with the use of a power electronic unit. The main aim of the control strategy is to transfer a maximum possible amount of energy produced by the water turbine or the wind turbine connected to a synchronous generator. The second purpose of the control method is to decrease the amount of higher harmonics of generator currents. The paper describes two basic methods which are used in control systems of the PWM rectifiers. The first one is the sinusoidal PWM method, and the second method relates to the hysteresis switching of the PWM rectifier transistors. A significant part of the paper is devoted to control principles of the PWM rectifier which cooperates with a variable speed PM synchronous generator. Special attention is paid to higher harmonics of PM generator currents with respect to individual methods.