Permanent Magnet Synchronous Wind Turbine Research Articles

Investigation on Overvoltage Distribution in Stator Windings of Permanent Magnet Synchronous Wind Turbines

The PWM voltage pulses output by the inverter reaches the stator winding of the wind turbine generator through the cable. Due to the impedance mismatch between the motor and the cable, the voltage at the motor end rises under the action of the circuit wave process; on the other hand, electromagnetic oscillation occurs within the motor winding. Higher overvoltage is generated under the combined effect of both, which greatly accelerates the aging and breakdown of the insulation layer of the permanent magnet synchronous wind turbine. In this paper, a three-dimensional electromagnetic model of the permanent magnet synchronous wind turbine generator is established. The distribution circuit parameters of the stator winding of the permanent magnet machine are calculated using the finite element method, and its circuit model is based. The voltage distribution of the stator winding under different PWM excitations is investigated by simulation software, and the effects of the time of the rising edge and the pulse width of the PWM pulse on the stator winding voltage to ground and the turn-to-turn voltage distribution are studied. The results show that the effect of the rising edge time is larger when the rising edge time is shorter, the maximum voltage to ground occurs in the first coil, and the amplitude can be up to 1.5 times of the output voltage. When the rising edge time is longer, the maximum voltage to ground occurs in the end coil, and the amplitude is slightly higher than the output voltage. The trend of turn-to-turn voltage variation is similar for different rising edges; only the maximum turn-to-turn voltage amplitude is different. Pulse width has a small effect on overvoltage and only occurs when the pulse width is less than 10 μs. The research results of this paper are of great significance in revealing the aging and breakdown mechanism of the generator stator insulation, as well as the insulation coordination and design.

Research on the design and optimization of 1.5 MW semi-direct drive permanent magnet synchronous wind turbine

The utilization of wind energy can alleviate the problems of fossil energy shortage and environmental pollution. As the core unit of wind power generation systems, improving the design and manufacturing technology of permanent magnet synchronous generator has become the research focus of researchers. In this paper, the key design technology of direct drive permanent magnet synchronous wind turbine, especially the semi-direct drive permanent magnet synchronous wind turbine with primary gear is studied, and a 1.5 MW semi-direct drive permanent magnet synchronous wind turbine is designed. To improve the power factor of the permanent magnet synchronous generator, the reactive power compensation device and filter circuit are added to the control circuit. The results show that after adding the reactive power compensation circuit, the power factor of the circuit can reach 1. In addition, due to the filter circuit, the fifth harmonic is reduced from 5.6% to 3.9%. The scheme of closed slot is used to weaken cogging torque and resistance torque of the permanent magnet synchronous generator. To improve the utilization of permanent magnet, a T-shaped rotor pole structure is proposed in this paper and the pole arc coefficient is selected between 0.65–0.70. Through the comparative analysis of various design schemes, the design scheme of 50 poles-180 slots is determined. The temperature rise of the permanent magnet synchronous generator is calculated by the thermal network method and ANSYS finite element analysis. The results show that the temperature rise of the design scheme is within the normal working range of the motor.

Novel Nonlinear Control and Optimization Strategies for Hybrid Renewable Energy Conversion System

This article deals with a hybrid renewable energy conversion system (HRECS) interconnected to the three-phase grid in association with their power conversion components, i.e., AC/DC rectifier and DC/AC inverter. The HRECS is built around a permanent magnet synchronous wind turbine generator and a photovoltaic energy conversion system. Comparing to traditional control methods, a new multiobjective control strategy is developed to enhance system performances. This makes it possible to account in addition to optimal turbine speed regulation and PV-MPPT and three other important control objectives such as DC-link voltage regulation and the injected reactive power in the grid. To achieve these objectives, a novel control strategy is developed, based on a nonlinear model of the whole “converters-generators” association. The robustness and the stability analysis of the system have been proved using the Lyapunov theory and precisely the backstepping control and the sliding mode control. The performances of the proposed controllers are formally analyzed with respect to standard control solutions illustrated through simulation.

10 kW Optimization of grid-connected wind power system and its application in Xiamen

Coastal areas not only have large annual average wind speed, but also have more days of strong winds in a year. Xiamen >8 gale days, 22.4 days a year, so it is very suitable for wind power generation. This design is 10 kW wind grid-connected power generation system, each branch is composed of permanent magnet synchronous motor, rectifier, boost module, inverter and filter, 20 groups are used in parallel to form 10 kW system. Choose a single permanent magnet synchronous wind turbine power of 500 W, need 20. System DC voltage :12 V, when the power is fixed, the proper lifting of DC voltage is helpful to reduce the current, thus preventing the IGBT from causing device damage due to overcurrent. A two-dimensional fuzzy controller is used to select the outer loop error and error differential signal as input variables. In order to verify the correctness of fuzzy adaptive PI control strategy, a system simulation model is built.

Research on cogging torque optimization design of permanent magnet synchronous wind turbine

Cogging torque is one of the unique problems of permanent magnet generators. Its main cause is the uneven distribution of the generator’s magnetic permeability, which directly affects the starting and running performance of the generator. The study of cogging torque suppression methods is of great significance for improving the operating stability and service life of generators. Through the analysis of the principle of cogging torque, an optimization method for the amplitude of cogging torque based on Taguchi algorithm for the two parameters of pole arc coefficient and skew angle is established. And the finite element analysis method is used to quantitatively compare the characteristic parameters of the generator model before and after the optimization by Taguchi algorithm. The results show that when the pole arc coefficient and the angle of the chute are in the optimal value at the same time, the cogging torque of the generator can be greatly reduced, and its air gap magnetic density waveform and induced electromotive force waveform are ideal, which provides a research method for the design and parameter optimization of large megawatt permanent magnet synchronous wind turbines.

Ripple Analysis and Suppression Method Research of Direct Drive Permanent Magnet Synchronous Wind Turbine under Wind Shear

Wind shear is among the important sources of torque fluctuation on mechanical side and output power fluctuation on electromagnetic side and grid connection point, which frequency are triple turbine rotation frequency. With the increase in wind turbine single capacity and wind power integration scale, the power fluctuation caused by wind shear cannot be ignored. The paper takes a direct-drive permanent magnet synchronous wind turbine (PMSWT) as the research object. Firstly, the fluctuation transfer mechanism model is established; then, the current ripple is extracted by a notch filter to calculate the voltage control signal to suppress power fluctuation actively by the DC link capacitor which absorbs fluctuation energy. The simulation experiment shows that the suppression strategy is effective and reliable.

Addendum of 2MW Wind Turbine to A Power with Directly-Driven Permanent Magnet Generation System

In recent years, wind turbine has become an acceptable alternative energy generation, because of the environmental and economic benefits. Notwithstanding more research works still need to be done to reduce wind turbine installation complexity, enhance profitability and reliability especially in developing countries like Nigeria. This paper presents the modeling and analysis of a 2MW variable-speed directly-driven permanent magnet synchronous generator (PMSG), Wind energy conversion system (WECS). The objective is to optimize the power captured from the wind, ensure optimum efficiency for power generation and reduce system hardware count. The mathematical model for the permanent magnet synchronous wind turbine and its power control algorithms are modified by removing the speed sensors. Further, enhancement was achieved by utilizing wind speed forecasts as the starting speed. A modified Field Orientation Control FOC and voltage orientation control VOC scheme were developed for the system using matlab Simulink CAD application. The Simulation results of the model for various changes in wind speed utilizing average wind speed data of Mmaku in Awgu local government area of Enugu state Nigeria. The developed system ability to ‘smoothen’ the power, voltage output and operates at the optimum coefficient of performance between the cut in speed of 3m/s and 12m/s without wind sensor is found to be promising, Key words : wind turbine, variable-speed, permanent magnet, synchronous generator, efficiency DOI : 10.7176/JETP/9-3-04 Publication date :March 31 st 2019

Switched model based control of dual-PWM converters in the direct-drive permanent magnet synchronous wind turbine system

Nowadays, permanent magnet synchronous generator (PMSG) based direct drive wind power generation systems are developing rapidly and are attracting more and more attention. Dual-PWM (pulse width modulation) converters, as full power converters of the direct-drive wind power system, have excellent performance and have been widely used in recent years. The effective control of the back-to-back Dual-PWM converters plays an important role in generating the wind power efficiently. As the back-to-back Dual-PWM converters of the direct-drive wind power generation system can be considered as switched systems according to their working characteristics, this study presents one switched model based control strategy for the control of the Dual-PWM converters. First, the switched dynamic models of the converters on the PMSG side and the grid side are established, respectively. In contrast to the traditional averaged or linearized models, the proposed models can be more precise because no approximation will be introduced when the wind speed changes. Then, in order to realize the highest convergent rate, the min-projection strategy based switched control laws are derived. Furthermore, the stability analysis is done to assure the global stability of the proposed control strategy. Finally, detailed simulations and experiments are available to verify the proposed control method. The simulation and experimental results demonstrate that the proposed models and the control strategy are correct and effective. Comparing with the conventional proportional-integral control method, this paper integrates the back-to-back Dual-PWM converters as part of the proposed controller and utilizes the states of the converters as control variables, and thus, faster torque dynamics can be achieved.

Wind Power Development in Power Grid and Study on Dispatching Strategy

Firstly, This paper summarizes the development situation of wind power in China, and analyzes the operation characteristics of all types of generating units one by one according to constant speed constant frequency asynchronous wind turbine, double-fed asynchronous wind turbine and direct-driven permanent magnet synchronous wind turbine. Then various effects of wind power integration on power grid are analyzed based on the actual situation of power grid. Finally, according to these effects, various measures of strengthening wind power integration management are proposed from management and technology levels. These measures are generally instructive and applicable to the same types of power grid with wind power.

A CMAC-PID based on pitch angle controller for direct drive permanent magnet synchronous wind turbine

The efficiency of wind power conversions systems can be greatly improved using an appropriate control algorithm. This paper deals with a cerebellar model articulation controller coupling with a proportional-integral-derivative controller for a direct drive permanent magnet synchronous wind turbine generator. First, the aerodynamic characteristics of the wind turbine have been studied in detail. Moreover, the transfer function from pitch angle to the speed of the wind turbine is established. Finally, some tests on the proposed method are carried out including random wind speed using numerical simulation. From these tests, several operating conditions are simulated, and satisfactory results are obtained.

Design and implementation of a microcontroller-based wind energy conversion system

In this study, a dsPIC-controlled DC/DC boost converter and a wind turbine control system that tracks the maximum power point are designed and implemented. In practice, the energy generated by a permanent magnet synchronous wind turbine is applied to the load using a circuit that consists of a rectifier, boost converter, and protective load. The converter operates in the designed mode 35% more efficiently than in the normal operation mode. In addition, the wind turbine is protected from overvoltages in strong windy weather using the protective circuit. Experimental results show that the ripple value on the direct current belonging to the converter output complies with the IEC 61204 standard. Moreover, the designed system is fast and easily programmable, and it can be adapted to other wind turbine models.

Analysis of Low Voltage Ride-Through Capability for Variable Speed Wind Turbines Using Experimental and Measured Data

With an increasing amount of wind energy installed, the behavior of wind turbines during grid disturbances becomes more and more important. This paper introduces the basic structures of doubly-fed wind turbines and direct-drive permanent magnet synchronous wind turbines and analyses the capability of low voltage ride through (LVRT) of the wind turbines. Finally this paper elaborates the principle and the procedures of the LVRT tests. The results of the tests show that: Doubly-fed wind turbines and direct-drive permanent magnet synchronous wind turbines are equipped with LVRT capability. The turbines are able to operate normally without disconnection and provide reactive power to support grid restoration during the dip. The direct-drive permanent magnet synchronous wind turbines are superior to the doubly-fed wind turbines on LVRT since a full-power converter is used.

Unity Power Factor Control of a Direct-Driven Permanent Magnet Synchronous Wind-Power Generator Based on Three-Level Converter

Direct-driven permanent magnet synchronous generator (PMSG) has become an important research subject besides the double-fed induction generator. With the increasing of unit capacity, the study of topology of high power converters based on multi-level converter is attracting more and more attention. The study of vector control of the direct-driven permanent magnet synchronous wind turbines based on three-level converter is carried out in this paper. Based on the maximum wind-energy capture control of the PMSG, the unity power factor operation of PMSG is realized by controlling the d-axis current to zero in the generator-side converter. A detailed comparative study of two-level system and three-level system is conducted. The simulation results verify the validity of this algorithm.

Investigating the overload capacity of a direct-driven synchronous permanent magnet wind turbine generator designed using high-voltage cable technology

Utilization of wind energy to maximum permissible limits for generating electrical power has become necessary to meet the global energy demands. Under such circumstances the present day conventional wind turbine generators pose a limitation regarding the overload capability, specifically significant when they need to operate in high-energy wind conditions. It is proposed that by employing a completely different generator winding concept, based on high-voltage cable technology, to a specific generator, it is possible to increase the generator overload capabilities and thereby making it operationally efficient in high wind speed situations. Therefore, the possibility of extracting more energy is predicted to increase. Simulations, based on finite-element methods combined with external circuit models for the generator, have been performed. The results demonstrate that under given thermal and electrical restrictions, a direct-driven permanent magnet synchronous wind turbine generator, based on high-voltage cable windings, is capable of being overloaded more than twice the rated power, thus making it very suitable for strong wind situations.