Modeling of an efficient high power wind energy conversion system using self-excited multi-phase machines

Self-Excited Multi-phase Induction Generators (SEMPIG) producing power from wind turbines infar-flung fields are receiving the interest of recent researchers. Small and medium energy wind generators involve 3-phase induction generators. SEMPIG with significant reliability, better fault tolerance, reduced harmonics, and high power-handling capability using reduced current per phase and maintaining the same per phase voltage makes it the promising contender in high-power WECS. This investigation analyzes the proficiency of energy efficient stand-alone self-excited seven-phase induction generator (SE7PIG) in wind energy schemes. This paper develops a cogent model from the two-phase equivalent circuit of SE7PIG using Matlab/Simulink. The study examines the modeling aspects of the SE7PIG with incorporated significant 7-rectifier and 7-phase inverter. The machine operational parameters speed, torque, voltage and current are presented. The 2MW WECS with 7-phase induction generator is analyzed with and without DC link converter. The results are compared with the 3-phase counterpart to illustrate the efficacy of SE7PIG for megawatt wind-power generation. The paper confirms the competence of SE7PIG with better fault tolerance and significant energy output with a decrease in phase current.     

模糊控制在离网风力发电最大风能捕获中的应用

研究了一种模糊PID实现的自调整变步长算法, 解决了爬山算法动态响应速度与稳态精度相矛盾的问题。分析了离网风力发电系统数学模型, 建立了不测转速的控制结构。在Simulink平台上对一个5kW离网风电系统进行了仿真分析。结果表明, 在平稳风速以及组合风速下, 该算法均能有效提高跟踪速度, 捕获更多功率。     

Energy-based coordinated control of wind energy conversion system with DFIG

This article presents an energy-based coordinated control of machine- and grid-side converters in a wind energy conversion system (WECS) with a doubly-fed induction generator (DFIG) based on the theory of port-controlled Hamiltonian (PCH) system. Taking into account energy transmission in the dual PWM converter rather than treating rectification and inversion as separate parts, an integrated PCH model for the whole WECS was established from physical meanings. And depending on the new model, an energy-based coordinated control approach was proposed to meet the control requirements of the WECS with an additional objective which was to limit the DC-link voltage fluctuation. The approach was applied on a 2MW WECS, and compared with the energy-based respective control strategy using MATLAB/Simulink. The results show that the proposed control approach provides faster dynamic performance since the two converters operate with the knowledge of each other's operating status, and thus is able to smooth the power flow in the DC-link more effectively.     

Adaptive Nonlinear Control of Wind Energy Conversion System Involving Induction Generator

This paper presents a theoretical framework for adaptive control of a wind energy conversion system (WECS), involving a squirrel cage induction generator (SIG) connected with an AC/DC/AC IGBT‐based PWM converter. A multi‐loop nonlinear controller is designed to meet two main control objectives, i.e., (i) speed reference optimization in order to extract a maximum wind energy whatever the wind speed, and (ii) power factor correction (PFC) to avoid net harmonic pollution. These objectives must be achieved despite the mechanical parameters uncertainty. First, a nonlinear model of the whole controlled system is developed within the Park coordinates. Then, a multi‐loop nonlinear controller is synthesized using the adaptive backstepping design. A formal analysis based on Lyapunov stability is carried out to describe the control system performances. In addition to closed‐loop global asymptotic stability, it is proven that all control objectives (induction generator speed tracking, rotor flux regulation, DC link voltage regulation and unitary power factor) are asymptotically achieved.     

Optimization of harmonics with active power filter based on ADALINE neural network

Mostly the power quality issues in the distribution line system happen due to the presence of harmonics. Especially, the nonlinear loads such as power electronic converters, high-speed semi-conducting switches, and solid state drives were the major causes for harmonics in distorted power system signals. Moreover, the estimation of magnitude and the phase of this harmful harmonic interference are necessary. By taking in to consideration of all the above factors, this paper develops an efficient technique for harmonic estimation and detection of the renewable wind energy resources and elimination of these harmonics will also be done accordingly for getting desired output from wind energy. 8 bit inputs (4 + 4) are collected and used to generate the intended input set for ANN training. The proposed work develops an Adaptive Linear Neural Network (ADALINE) for the estimation of harmonics which is the novelty of this work. For making the harmonics content more negligible and to enhance the load power quality, an Active Power Filter (APF) is used. The novel control design is developed with a Pulse Width Modulation (PWM) control. In addition, feed forward networks (trained by back propagation algorithm) works like a hysteresis band comparator. An APF control design is developed with ADALINE network in which the load and current along with voltage will be analyzed and then the controller will be calculating the control signal by considering the reference compensation current. Afterwards, the power system is injected with compensating current. The simulation is carried out with Matlab-Simulink laboratory prototype is developed with Xilinux 3E Spartan FPGA board to verify the proposed control designs. The proposed work is compared with exiting method comprising Shunt Active Power Filters (SAPF) with ADALINE for the performance perspectives. This method was found to be effective in terms of many parameters such as load voltage, load current, voltage, reactive power, real power and especially THD value than those of the existing works which are considered.     

LPV动态补偿的风能转换系统变桨距控制

当风速超过额定值时,风能转换系统需要控制节距角来实现额定恒功率控制.同时控制电机电磁转矩使转速维持在其额定值以减少系统振荡.建立了风能转换系统的机理模型并得到其线性参数变化(LPV)系统模型;在多变量(MV)控制策略的基础上,设计了基于LPV模型的增益调度控制器,对节距角和电磁转矩进行动态补偿;基于dSPACE的风能转换系统硬件在回路仿真平台进行实验研究,结果表明补偿后系统的功率误差更小,电机转速及转矩的波动明显减小,体现了更好的动态性能.     

Output feedback control of wind energy conversion system involving a doubly fed induction generator

This paper deals with the problem of controlling a wind energy conversion system (WECS) based on the doubly fed induction generator (DFIG), by IGBT‐based back‐to‐back rectifier‐inverter. The goal of control is to maximize wind energy extraction letting the wind turbine rotor operate in a variable‐speed mode. Interestingly, the present study features the achievement of the above energetic goal without resorting to sensors for wind velocity. The control strategy involves: (i) an output feedback non‐linear regulator designed by the backstepping technique and based on the use of a high gain observer; (ii) a sensorless online reference‐speed optimizer designed using the turbine power characteristic to achieve the maximum power point tracking (MPPT) requirement. It is formally shown that the proposed controller actually meets its control objectives. This theoretical result is confirmed by several simulations.     

风能转换系统执行器故障重构与容错控制

针对风能转换系统中执行器故障,论文提出了一种新型的主动容错控制策略.设计滑模故障观测器,实时动态采集执行器故障前后数据信息,对执行器故障进行重构,达到故障诊断的目的.通过补偿控制,保证了滑模控制器对风能转换系统的可靠控制输入,以达到对执行器故障主动容错的功能.仿真结果表明,滑模故障观测器模块能够实时精确地重构风能转换系统执行器故障,主动补偿容错控制器在不影响风能转换系统动态性能的情况下,仍能实现系统的最大风能的捕获.     

A second-order sliding mode and fuzzy logic control to optimal energy management in wind turbine with battery storage

The optimal control of large-scale wind turbine has become a critical issue for the development of renewable energy systems and their integration into the power grid to provide reliable, secure and efficient electricity, despite any possible constraints such as sudden changes in wind speed. This paper deals with the modeling and control of a hybrid system integrating a permanent magnet synchronous generator (PMSG) in variable speed wind turbine (VSWT) and batteries as energy storage system (BESS). Moreover a new supervisory control system for the optimal management and robust operation of a VSWT and a BESS is described and evaluated by simulation under wind speed variation and grid demand changes. In this way, the proposed coordinated controller has three subsystems (generator side, BESS side and grid side converters). The main function of the first one is to extract the maximum wind power through controlling the rotational speed of the PMSG, for this a maximum power point tracking algorithm based on fuzzy logic control and a second-order sliding mode control (SOSMC) theory is designed. The task of the second one is to maintain the required direct current (DC) link voltage level of the PMSG through a bidirectional DC/DC converter, whereas in the last, a (SOSMC) is investigated to achieve smooth regulation of grid active and reactive powers quantities, which provides better results in terms of attenuation of the harmonics present in the grid courant compared with the conventional first-order sliding controller. Extensive simulation studies under different conditions are carried out in MATLAB/Simulink, and the results confirm the effectiveness of the new supervisory control system.

     

Sensorless wind energy conversion system maximum power point tracking using Takagi–Sugeno fuzzy cerebellar model articulation control

In this paper, we propose a sensorless wind energy conversion system (WECS) maximum wind power point tracking using Takagi–Sugeno fuzzy cerebellar model articulation control (T-S CMAC). The main objective of the WECS is to achieve maximum power transfer under various wind speeds without actual measurement of the wind velocity. We first represent the WECS, which uses a permanent magnet synchronous generator (PMSG), as a nonlinear dynamical model. To carry out the T-S CMAC design, we rewrite the WECS model as a T-S fuzzy representation. The T-S CMAC design is inspired by the architectural similarity of the T-S fuzzy control and CMAC where accordingly the PDC design control gains and weighting parameter are augmented into a single vector. The advantages of this approach are 3-fold: (i) increases accuracy of CMAC initial weights – we assign the initial weights of CMAC using the control gains solved by the LMIs from the PDC design; (ii) introduces adaptive ability in LMI-based design – the CMAC design allows time-varying parameters in the system; and (iii) relaxes assumption on system uncertainty – we drop the assumption that a strict upper bound on system uncertainty is known. Numerical simulations under various wind speeds show exponential convergence results which further verify the theoretical derivations.     

电网电压不对称跌落下直驱风电系统控制策略

针对电网电压不对称跌落下直驱风电系统并网运行过程中出现的直流环节过电压、并网电流畸变、并网功率波动问题,在直驱风电系统并网变换器的直流环节并联超导磁储能系统;同时在分析电网电压不对称跌落下网侧变换器数学模型的基础上,采用抑制并网功率波动的正负序电流控制对网侧变换器的控制策略加以改进,从而稳定直流环节电压、改善并网电流品质、抑制并网功率波动。仿真结果验证了该控制策略的正确性和有效性。     

A rotor speed estimation algorithm in variable speed permanent magnet synchronous generator wind energy conversion system

A rotor speed estimation algorithm in a direct vector controlled permanent magnet synchronous generator wind energy conversion system is proposed. The proposed method is based on a simple equation obtained from the flux model of the machine and contains only stator flux and current. Constant gain recursive least squares estimator is used for implementing the speed estimation algorithm. Rotor position information used for coordinate transformation is computed using the estimated speed. Stator flux information required by the speed estimator is obtained using the stator voltage equation by implementing a programmable low pass filter. The estimated speed is used as the feedback signal for the speed control loop of the vector controlled machine side converter control system whose command speed is obtained from a wind speed sensorless maximum power point tracking controller, thus, we obtain a complete rotor speed and wind speed sensorless permanent magnet synchronous generator wind energy conversion system. Simulation is carried out to validate the performance of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.     

基于NSGA-II的并网型风光互补发电系统协调控制

针对并网型风光互补发电系统中,系统最大输出功率大于给定功率时,风力发电子系统和光伏发电子系统功率如何协调的问题,提出了一种功率协调控制方法.在该方法中,根据系统并网收益最大和输出电流谐波最小构建目标函数,采用带精英策略的快速非支配排序遗传算法对风力发电子系统和光伏发电子系统的输出功率进行多目标优化,协调控制子系统的发电功率;并以甘肃华电阿克赛风光互补发电项目为例进行了仿真验证.仿真结果表明,与传统的光伏优先接入方式相比,基于NSGA-Ⅱ的并网型风光互补发电系统协调控制方法可以更加合理地利用风能和太阳能,提高新能源电能的电网友好性.     

不平衡电网电压下双馈风力发电系统强励控制

针对电网电压不平衡造成的双馈风力发电机(DFIG)定子有功和无功功率振荡、电磁转矩脉动、定、转子电流不平衡等问题,提出了一种双馈风力发电系统转子侧变换器强励控制方案。推导了不平衡电网电压下DFIG定子有功、无功功率的二次谐波分量在同步旋转坐标系中的表达式,并以此为依据设计了电压强励补偿环。分析了有功、无功功率,电磁转矩及定、转子电流二次谐波分量之间的关系,采用单一强励补偿控制器对不同控制目标进行切换强励控制。对1.5MWDFIG系统的控制特性研究验证了所提控制策略的可行性和优越性。     

变速恒频双馈风力发电系统网侧变流器控制策略研究

变速恒频双馈风力发电系统通常采用磁链定向、转子磁链定向和气隙磁场定向进行控制,这些控制系统的结构设计复杂,控制精度不高。为了进一步提高风力发电系统的控制效果,论文对变速恒频双馈风力发电系统的双P W M变流器进行了详细的分析,针对网侧变流器建立了数学模型,对网侧变流器的控制策略进行了研究,并采用电压、电流双闭环控制策略对系统中的网侧变流器进行控制。仿真结果显示,双闭环控制策略系统经过短暂的振荡之后能够快速实现状态的转变,达到预期效果。     

Adaptive steering‐based HDTC algorithm for PMSM

This paper introduces sensorless hysteresis direct torque control for permanent magnet synchronous motors to provide a reduced torque pulsation profile, which leads to a smaller mechanical vibration. The suggested algorithm utilizes the principle of vehicle steering, which continuously fixes the direction of the vehicle in the track. Moreover, the algorithm efficiently employs the output of torque and the output of flux error controllers used in basic hysteresis direct torque control to select two nonzero adjacent vectors. The initial switching time for the selected vectors is determined by a function that considers the absolute magnitude of the torque error and the magnitude of the flux error in addition to the space angle position of the stator flux. To reduce the processing time in the control signal flow, a suggested structure for switching the initial time of the selected vectors is developed. The final switching time of the vectors is adaptively adjusted according to the minimum required stator voltage to drive the load and according to the stored rotor energy that arises due to the inertia of the mechanical load connected to the motor shaft. The simulation results along with the experimental results show a fast dynamic response of torque, relatively reduced torque ripples, and reduced current harmonics compared to the basic hysteresis direct torque control.     

基于无差拍控制的超导磁储能系统

超导磁储能(SMES)系统具有功率密度高和功率指令响应快等特点,在平滑风力发电功率波动、提高电力系统稳定性等方面具有广阔的应用前景。针对当前SMES控制存在超调量大、控制精度不高等缺陷,将无差拍控制引入SMES的控制中。首先建立了SMES数学模型并介绍了无差拍控制的一般设计方法,然后根据SMES数学模型设计了SMES的无差拍控制策略,最后在MATLAB/SIMULINK中对所提控制策略进行了仿真。仿真结果表明,所提的控制方法具有跟踪无过冲、控制精度高和SMES变流器网侧电流谐波含量小等特点;将其应用于平滑双馈风机有功功率输出,有效平滑了双馈风机的功率波动,提高了双馈风机的并网能力。证明了该控制策略的有效性和优越性。     

Energy-based modeling and control for grid-side converter of doubly fed wind generator

To avoid dealing with the zero dynamics limitation brought by the bidirectional power flow through the back-to-back converter in a doubly fed wind generator,a new energy-based modeling and control approach for the gridside converter is presented.During the modeling process,the grid-side converter is divided into two subsystems with the feedback interconnection structure,and the interactive matrix of the model takes into account the concrete port structure. Then,an energy-based controller is proposed to realize the grid-side control objectives based on the new model.Simulation studies are carried out in MATLAB/Simulink.Comparative results between the proportional-integral controller and the energy-based controller show that the latter one can obtain faster convergence rate and global stability as the load current varies.Moreover,the energy-based controller is also competent for grid-side control when simulated in a 2 MW wind energy conversion system with random wind.     

Particle swarm optimization technique for multilevel inverters in solar harvesting micro grid system

In on grid solar generation system the irradiance causes voltage mismatch as a result of this the nonlinearities increase in the output voltage of the multilevel inverter. The sunlight is not uniform at all places, variation in irradiance is inevitable when it comes to solar power. The Solar power is not similarly circulated there is a change in sun orientation with respect to geometrical positions. The un symmetrical voltage results in unbalancing and introduces more harmonics. The article proposed here analyses a topology where a DC-DC converter is utilized ahead of the multilevel inverter so as to overcome the voltage varieties, thereby reducing the harmonics in the system. Particle swarm optimization is carried out in minimizing the Harmonics. Different observation and studies working stages their simulations and results for both are studied and recorded. Since solar energy is an essential, a complete analysis of this is done. A variety of initial calculations in designing the converter are also carried out. Similar calculations are also carried out informing the solar panel and harvesting the energy. By facilitating MATLAB simulation of particle swarm optimization for firing angles employed in multilevel inverter along with the converter. The measure of total harmonic distortion THD obtained is taken as a measure of evaluation for the performance of this combined system.     

一种用于飞机交流电源系统的有源滤波器

针对飞机三相四线制电源系统的特点及现有电能质量控制方法的不足,提出了一种基于自适应陷波器、瞬时对称分量算法及滞环电流控制方式的飞机交流电源的有源滤波器。所提方法能够有效地消除飞机交流电源电流中的谐波及中线电流,补偿无功以及平衡三相电流。理论推导和仿真结果表明,该方法能够准确快速地检测出飞机三相四线制电源系统中的谐波电流,具有较好的动静态性能。