双馈风力发电机状态监测系统软件设计

采用双馈风力发电机状态监测系统可及时发现并跟踪风电机组主要部件的机械和电气故障,有效降低机组的运行维护成本,保证风电机组的安全稳定运行.软件采用模块化设计思想,主要功能包括管理、诊断、监测、查询、数据存储、数据备份等.通过对振动、电流、电压、温度等参量进行分析,该软件实现了诊断发电机定子和转子匝间短路、相间短路、相对地短路、轴承故障的功能.将该系统试用于某风电场1.5 MW双馈发电机组上,结果表明其可用于监测和诊断双馈风力发电机.     

基于SVG的风电场接入局域电网的电压稳定性分析

研究了用静止无功发生器(SVG)改善基于双馈感应发电机组的风电场的暂态电压稳定性。在DIgSILENT/PowerFactory中建立了双馈感应发电机组及SVG控制模型,通过包含风电场的电力系统仿真,验证了SVG对风电场暂态电压稳定性的作用。仿真结果表明,SVG能够有效地帮助风电场在电网发生故障后迅速恢复电压,提高风电场的故障穿越能力,确保风电机组连续运行及电网安全稳定。     

An improved model predictive control of low voltage ride through in a permanent magnet synchronous generator in wind turbine systems

This research investigates a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). In addition, a model predictive control (MPC) is proposed for the PMSG in normal and fault conditions. The most efficient mode of the control algorithm is found for maximum power point tracking in normal conditions and fast dynamic response in fault conditions following the selection of the optimum voltage vector. This method prevents a sudden increase in the DC‐link voltage by storing the active power in the generator rotor inertia. Moreover, during the low voltage, the grid code adoption of the reactive current is injected into the grid side. The performance of the proposed control scheme is evaluated for a wind power generator using MATLAB software. The simulation results demonstrate that the proposed method can safeguard the DC‐link during the fault.     

电网电压不平衡工况下双馈感应风力发电机组的自抗扰控制

本文提出电网电压不平衡工况下双馈感应电机(DFIG)的自抗扰控制(ADRC)方法, 抑制不平衡电压引起的电磁转矩和无功功率波动, 延长风力发电机组的工作寿命. 在正、负序同步旋转坐标系中推导了电网电压不平衡工况下DFIG的电磁转矩表达式, 计算出消除电磁转矩波动所需的负序转子电流, 将其叠加到正序转子电流参考值上, 以减小电磁转矩波动. 采用ADRC实现对转子电流的有效控制, 减少控制器对发电机精确模型的依赖, 提高控制系统的鲁棒性. 仿真结果表明所提出的控制方案有效地减小了电网电压不平衡工况下DFIG的电磁转矩和无功功率波动, 同时减小了不平衡电流, 有利于延长DFIG风力发电机组的工作寿命.     

双馈系统在电网故障下不间断运行的研究

为更好地研究风力发电机在一定的电网电压跌落故障下的动态响应,以单台1.5 MW双馈风力发电机(DFIG)为研究对象,设计了Crowbar电路,通过构建电网电压跌落仿真模型,分别对机端电压、电流、转子电流、输出的有功功率和无功功率、直流侧电压、电磁转矩在故障期间的动态响应进行了仿真。探讨了相应的控制策略,为进一步研究低电压穿越标准下的控制策略提供了依据,同时也为研制兆瓦级变频器打下基础。测量结果表明这种控制方式能使DFIG在电压跌落故障下实现不间断运行,有效提高了DFIG风电机组运行的可靠性。     

理想电网条件下双馈风力发电系统低电压穿越技术的控制策略研究

随着风电在电网所占比例的不断增大,提高风机在故障条件下的不间断运行能力越来越重要。通过分析交流励磁变速恒频双馈风机的运行特点,建立双馈风力发电系统的并网数学模型;针对电网电压小幅对称跌落,在不增加硬件成本的基础上,改进传统双馈发电机矢量控制策略,加入前馈补偿项来抑制电压小幅跌落时转子中的过电流,提高双馈风力发电系统的低压穿越能力。在MATLAB/SIMULINK中验证控制策略的合理性,为以后深入研究双馈风力发电系统提供了基础。     

基于状态观测器的双馈风电机组变流器开关管开路故障检测

针对双馈风电机组变流器可靠性较差,一旦变流器开关管发生故障,整个风电机组可能遭到严重损坏甚至导致停机的问题,提出一种基于状态观测器的双馈风电机组转子侧变流器开关管开路故障检测方法.根据双馈风电机组拓扑结构,结合其感应电机和变流器进行整体建模;构建状态观测器以实现对转子侧电流的在线估计并生成残差;将残差与设定的阈值比较,判断是否有故障发生.仿真结果证明该方法可行且有效.     

基于二阶滑模控制的变速双馈风力发电系统最大功率点跟踪

本文提出一种超螺旋二阶滑模控制方案同时实现双馈变速风力发电系统最大风能捕获和无功功率调节.通过设计两个二阶滑模控制器,实现控制目标,降低机械磨损,提高控制精度,通过调节发电机转子电压,跟踪风机最优转速和转子电流设定值,实现额定风速以下的最大风能捕获和无功功率调节.采用二次型李雅普诺夫函数确定控制参数范围、确保系统有限时间稳定性.1.5 MW风机系统仿真实验验证所提方案有效性.     

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。     

基于位置估计的双馈风力发电机的控制策略

为了避免由机械传感器所带来的一些控制上的问题,提出了一种基于位置估计的双馈风力发电机的控制方案。在转速控制阶段,根据双馈发电机数学模型,通过采集电网电压电流,转子电压电流,采用定子磁场定向的矢量控制策略,利用转子电流矢量综合位置与定子电压矢量综合位置,对并网前后转子位置进行估算,得到转速及功率变化规律,运用这个规律可以实现对转速的控制。最后对1 MW的风力机模型进行系统仿真实验,结果表明整个转速控制区间对转子位置的估计都满足系统要求,基本上解决了风力发电机的转速和无功功率控制难的问题,验证了方案的正确性与可行性。     

New simulation approach for tuneable trapezoidal and rectangular piezoelectric bimorph energy harvesters

Enhancing and optimizing the power and operating frequency range of energy harvesters (EH) are important objectives in designing an energy harvester generator. The application of trapezoidal shaped piezoelectric (PZT) cantilever is one way of increasing the harvested power of energy harvesters. Finite element software was used to simulate a tuneable trapezoidal and a rectangular PZT bimorph cantilevers with similar specifications. From the new simulation approach, an open circuit voltage obtained for different resonance frequencies for both generators. The simulation results are compared with the experimental and found to be in good agreement. The results have showed an increase in power over 19 % for the trapezoidal generator over the rectangular generator for a frequency range of 38–122 Hz. The trapezoidal harvester produced maximum power of 0.272 mW at resonance frequency of 34 Hz and acceleration of 2.5 m/s².

     

基于仿真建模方式的MW级风力发电机测试平台

通过仿真建模方式建立的风力发电机测试平台是风机研发和性能质量检验的一种重要手段。研发设计了最高容许测试容量为3．6MW的双馈整机（DFTIG）全功率测试平台,其中采用了10kV中压并网电压和中压矩阵变频器,消除了常规测试台低电压并网的大电流弊端。本文重点论述该测试平台仿真建模及研发设计的关键技术,最后给出相关测试结果。     

风力发电系统技术的发展综述

风能是目前全球发展最快的可再生绿色能源,风力发电系统是将风能转化为电能的关键系统,它直接关系到风力发电的性能与效率。分别介绍了风电系统涉及的控制技术、风力机和发电机,特别是对当前的风力发电机系统进行了科学分类;并详细分析和比较了各类风电系统的原理、优缺点和适用范围,最后指出了风电系统的发展趋势。这对风力发电系统的选择和研究具有一定的参考指导价值。     

Direct Power Control of Dfig by Using Nonlinear Model Predictive Controller

This paper proposes a nonlinear model predictive direct power control (PDPC) strategy for a double fed induction generator (DFIG)‐based wind energy generation system. Active and reactive power variations of DFIG are calculated based on machine rules, and a nonlinear model of DFIG is given. A nonlinear model predictive controller (NMPC) is presented based on the useful cost function and constraint that it results in more proximity between simulations and reality. The power and current ripples are reduced and the optimal rotor voltage is generated based on an objective function and the constraints. The rotor voltage vector is calculated in the synchronous reference frame and transferred into the rotor reference frame. Simulation results of a 2 MW DFIG system show good performance of the proposed method during variation of active and reactive powers, machine parameters, and wind speed. Also, the transient responses of active and reactive powers are within a few milliseconds.     

双馈型变速恒频风力发电系统的鲁棒控制

研究了双馈变速恒频风力发电系统的鲁棒控制问题. 采用定子磁场定向的矢量变换技术, 建立了系统非线性数学描述, 利用非线性鲁棒控制技术, 设计了能实现发电机输出有功功率和无功功率鲁棒解耦控制, 同时具有鲁棒干扰抑制作用的转子励磁控制器. 理论分析和仿真结果均表明, 所设计的控制器可以保证在风速变化、系统参数不确定性和外部干扰的情况下, 风力发电系统仍能安全可靠地最大获取风能, 并且输出恒频恒压的电量.     

HIERARCHAL CONTROL SYSTEM FOR A VARIABLE SPEED CAGE MACHINE WIND GENERATION UNIT USING NEURAL NETWORKS

A hierarchal control strategy, that addresses three control objectives for a wind generation system, is proposed in this paper. It controls the local bus voltage (to avoid voltage rise), captures the maximum power in the wind and also minimizes the power loss in the induction generator. In the first level, given the instantaneous wind speed, electrical torque and output power, the designed neural networks calculate the desired rotor speed, air‐gap flux and the grid side reactive power. In the second level, the desired current wave shapes (instantaneous three‐phase currents) of the rectifier and the inverter in a double‐sided PWM converter system are calculated. In the third level, the PWM controller guides the system towards the optimum operating conditions. Simulation results show that even as the wind speed changes randomly, the proposed control strategy leads the system to the optimum operating conditions.     

静止无功发生器在风电场电网中的应用研究

分析并比较了晶闸管控制电抗器型无功补偿装置和静止无功发生器的动态响应时间和谐波特性,得出静止无功发生器动态响应速度更快、谐波含量更低的结论;对静止无功发生器在风电场电网正常运行和发生三相接地短路故障时的应用情况进行了仿真研究,结果表明,静止无功发生器可在风电场电网正常运行时降低输电线路损耗、抑制并网点电压的波动和闪变,在电网发生短路故障时增强风机低电压穿越能力;在某风电场通过断开静止无功发生器端子排上330kV母线PT空气开关来模拟电网三相接地短路故障,测试结果证明,静止无功发生器能够在较短的时间内达到最大容性无功输出,提高了电网运行的稳定性。     

基于SIMULINK的同步直驱风力发电机并网控制研究

本文简要介绍了风力发电中并网控制要求和同步直驱风力发电机并网的控制原理，并针对同步直驱风力发电机的并网控制方式进行了讨论分析：在SIMULINK软件中按照分析的结果进行建模并实验，用SVPWMA方式实现了对输出电压的控制；仿真结果表明该种控制方法可以满足风力发电机的运行需要。     

双馈风电机组的自适应神经网络保性能虚拟同步机控制

近年来，可再生能源的电网渗透率逐年提升，电网对可再生能源参与一次、二次调频的需求也愈加紧迫，虚拟同步机技术（VSG）应运而生.VSG能够赋予新能源机组主动参与电网调频的能力，然而当VSG应用于双馈感应风力发电机（DFIG）时，存在动态过程中转子电流超出转子侧变流器（RSC）容量的风险.本文提出一种应用于DFIG的保性能虚拟同步控制器，通过使用误差映射函数将输出受限的系统转化为等价的不受限系统，并使用李亚普诺夫方法设计保性能控制器，保证转子电流在调频、故障穿越等强动态过程中不超过任意人为设定的限制；此外，利用神经网络自适应策略，对发电机组中的不确定动态特性进行补偿，从而获得理想的控制效果.最后，本文通过大量仿真验证了所提控制策略在调频能力、转子电流控制和应对参数偏差等方面的控制性能.     

MGWO-PI controller for enhanced power flow compensation using unified power quality conditioner in wind turbine squirrel cage induction generator

Power quality is considered to be the major challenging one in the realization of the smart grid. So as to compensate for the issues occurring in power quality, active power filter (APFs) is mainly chosen as they are capable of filtering fast and has some active compensation. Also, load current related power quality constraint can be solved, such as unbalanced power, huge (Total harmonic distortion) THD level, and reduced power factor. For correcting the inappropriate supply of voltage and load current, the unified power quality conditioner (UPQC) and an effective integration of wind turbine are employed. A UPQC is a group of both shunt and series APF in a continuous manner having a conventional DC link capacitor. The voltage control of the DC link capacitor is significant in attaining a preferred performance on UPQC. In this paper, the UPQC with a Modified Grey Wolf Optimization (MGWO) based PI controller integrated with renewable energy like Wind turbine squirrel cage induction generator (SCIG) was implemented for the elimination of voltage and current harmonics imperfection precisely. Likewise, the Modified Grey Wolf Optimization (MGWO) was also exploited in UPQC. The performance analysis was made with UPQC, without UPQC, and with MGWO & UPQC and the simulation, outcomes are estimated and compared for the parameters THD values, load voltage and current. Also, the performance analysis was implemented in hardware prototype set-up and the results attained are depicted.