变速恒频双馈发电独立电源的励磁控制策略

根据变速恒频双馈发电独立电源的运行情况,提出了一种采用定子磁场定向的交流励磁变速恒频双馈发电机模型及控制策略,分析了电机运行的稳态和动态性能.仿真结果表明,采用矢量定向控制,发电机与原动机之间可以完全解耦,发电机定子电压、定子电流的频率、相位与转子的实际转速和瞬时位置无关.     

矩阵变换器励磁双馈调速系统的建模与仿真

双馈调速能够实现转速和无功的独立调节，具有广阔的应用前景。矩阵变换器以其优良的特性成为双馈电机转子励磁电源的理想选择。建立了矩阵变换器励磁的双馈电机定子电压定向的矢量变换控制模型，利用MATLAB／Simulink仿真平台进行了仿真研究。仿真结果验证了该方案的正确性和有效性。     

双馈风力发电机组转子侧变换器滞环矢量控制技术的研究

变速恒频双馈风力发电系统的交流励磁控制是通过转子侧PWM变换器来实现的,因此对转子侧PWM变换器控制策略的研究与整个风力发电系统的运行和控制紧密相连。常规的控制方法十分复杂,且动态响应性能一般。本文采用定子磁链定向矢量技术,引入滞环电流控制,建立了新的转子励磁控制策略,简化了控制过程,提高了动态响应性能。利用PSCAD/EMTDC平台,仿真研究并验证了该控制方案的正确性和有效性。     

交流励磁发电机定子磁场定向的矢量控制研究

论述了交流励磁发电机基于定子磁场定向的控制原理,推导了发电机有功功率、无功功率与转子励磁电流的关系,搭建了交流励磁发电机双闭环控制模型,讨论了定子磁链幅值和位置的确定,进行了采用PID调节器双闭环控制的仿真研究,结果表明定子磁场定向的矢量控制原理能够实现对交流励磁发电机有功和无功功率的快速、解耦控制     

双馈风力发电机有功、无功的解耦控制研究

交流励磁发电机又称双馈感应发电机（DFIG）。通过调节发电机转子绕组励磁电流的频率、幅值和相位即可实现变速恒频运行。通过对交流励磁发电机动态数学模型的研究,提出了基于定子磁场定向的矢量控制策略。并进行了有功和无功功率独立调节的仿真实验,仿真结果验证了控制策略的正确性。     

矩阵变换器励磁双馈调速系统的建模与仿真

双馈调速能够实现转速和无功的独立调节,具有广阔的应用前景。矩阵变换器以其优良的特性成为双馈电机转子励磁电源的理想选择。建立了矩阵变换器励磁的双馈电机定子电压定向的矢量变换控制模型,利用MATLAB/Simulink仿真平台进行了仿真研究。仿真结果验证了该方案的正确性和有效性。     

并网双馈发电机电网电压定向励磁控制的研究

在分析并网双馈发电机传统矢量控制策略的基础上，提出了一种基于电网电压定向的励磁控制策略。该控制策略仅需要定子侧电流、电网电压和转子位置角信号，避免了矢量控制系统中对定、转子量测量精度、实时性和一致性的严格要求，使控制系统得到了简化。利用该文提出的控制策略对双馈发电机有功、无功和转速稳态调节特性及机端三相对地突然短路的过渡过程进行了仿真研究，结果表明该控制策略能实现双馈发电机有功、无功和转速的解耦控制及短路故障切除后其有功、无功和转速都能回到原来的设定值稳定运行。     

TSMC励磁的风力发电系统空载并网控制

双级矩阵变换器(TSMC)存在中间直流环节,但不包含大容量直流环节储能电容,引入TSMC作为双馈风力发电系统的励磁电源。根据交流励磁变速恒频风力发电运行的特点,将电网电压定向的矢量控制技术应用在双馈发电机的并网控制上。根据电网电压和电机转速来调节转子的励磁电流,使双馈风力发电机定子电压跟随电网电压,从而减少并网时的冲击电流。实验结果表明,TSMC励磁双馈风力发电系统并网冲击电流较小,控制策略可行。     

变速恒频双馈风电机组转子侧励磁变流器控制技术研究

介绍了变频恒速双馈风力发电机的数学模型,分析了双馈风电机组转子侧变流器对发电机励磁的定子磁链定向的矢量控制策略,论述了采用定子磁场定向的矢量控制可以实现双馈风力发电机输出的有功功率和无功功率解耦.阐述了变速恒频双馈风电机组转子侧变流器励磁控制策略的仿真研究和试验波形.     

双馈异步电机矢量控制系统性能分析

根据矢量控制理论和自动控制原理，建立了转子磁链定向的双馈异步电动机电流模型矢量控制系统。该系统使用了一种新的电流控制器，以改善电机转子电流波形。控制系统可以单独控制电机的转速和无功功率，使其工作在超同步、弧同步、转子电流量最小和全补偿工作方式下。理论分析和仿真结果表明，这种控制策略有较好的动态与静态调节性。     

Effects of electrical and mechanical parameters on the transient voltage stability of a fixed speed wind turbine

In this paper the dynamic behaviour of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed with the Simulink simulation tool (Matlab Inc.) It is composed of the induction generator, the shaft system, an aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phase fault is applied close to the wind turbine and cleared by disconnecting the faulty line.The rigorous implementation of the simulink model allowed the authors to evaluate the exact dependence of various electrical parameters for the induction generator on voltage stability. Furthermore, the effects of wind turbine mechanical construction and of grid parameters on voltage stability are also evaluated and discussed.For each parameter, the terminal voltage and the generator rotor speed for different fault-clearing times are drawn. Finally, the terminal voltage and the generator rotor speed obtained for a fifth order model of the induction generator are compared with those obtained for a third order model. The differences between the two models are discussed. The results will help to understand transient stability phenomena in wind farms.     

Model and Performance of Current Sensor Observers for a Doubly Fed Induction Generator

Abstract—This article presents a stator and rotor current observer for a doubly fed induction generator. First, the dynamic models of the wind turbine drive train are presented, and the vector control strategies of a doubly fed induction generator for the rotor-side and grid-side converters are described. A stator and rotor current observer model, which is based on the state–space models of doubly fed induction generators, is then derived by using the stator and rotor voltage signals as inputs. To demonstrate the effectiveness of the proposed current observer, its dynamic performance is simulated using a MATLAB/Simulink software platform under the conditions of active power change of doubly fed induction generators and grid voltage dip fault. Furthermore, the robustness of the proposed current observer is investigated when the doubly fed induction generator rotor resistance is changed. Results show that the proposed observer has good coherence and robustness with the current sensor output when the doubly fed induction generator is in dynamic and transient responses. Compared with the referenced bilinear observer, the proposed observer has better fault-tolerant ability when the fault in the observed current sensor occurs.     

Grid-fault ride-through analysis and control of wind turbines with doubly fed induction generators

This paper deals with the low voltage ride-through (LVRT) control of wind turbines with doubly fed induction generators (DFIGs) under symmetrical voltage dips. The investigation first develops a mathematical formula for the rotor current and rotor voltage when DFIG is subjected to a symmetrical voltage dip. From the analysis, the reasons of rotor inrush current and factors influencing it are inferred. Then, a control scheme enhancing the wind turbine LVRT capability is designed and simulated. The proposed control scheme consists of a nonlinear control strategy applied to the rotor-side converter and a dc-link voltage control applied to the grid-side converter. It improves the damping of DFIG transient response and minimizes oscillations of rotor current, electromagnetic torque and dc-link voltage during the generator voltage dip. It also limits the peak value of these quantities. At the end, results of theoretical analyses are verified by time domain simulations.     

采用协同控制理论的同步发电机非线性励磁控制

提出了一种基于协同控制理论的非线性励磁控制器。首先依据同步发电机励磁控制的基本要求和特点,选择机端电压、有功功率和转子角速度三个变量的偏差的线性组合构成流形,以保证有效控制机端电压和抑制系统功率振荡。然后以同步发电机非线性模型为对象,推导出了非线性协同励磁控制器（Synergetic excitation controller,SEC）的控制律,并根据电力系统的运行特性,探讨了控制器参数的选取原则。最后,单机无穷大系统仿真结果表明,无论在大扰动还是在小扰动下,所提非线性协同励磁控制器比常规的AVR+PSS方式下的励磁控制器都能更快更精确地调节机端电压,还能够有效地抑制系统的功率振荡。     

基于预测虚拟转矩控制的DFIG并网逆变方法

针对双馈风力发电机组(DFIG)高性能并网控制问题,提出一种DFIG并网逆变系统预测虚拟转矩控制方法。虚拟转矩的概念衍生于直接转矩控制中的电磁转矩,是由DFIG的转子磁链和电网虚拟磁链合成产生的。在建立DFIG并网逆变系统数学模型的基础上,分析了不同扇区中电压矢量对系统虚拟转矩、转子磁链的影响趋势,选取一个包含两个有效电压矢量和一个零电压矢量的三矢量序列,并给出功率无差拍跟踪时的矢量作用时间求取方法。最后,基于55 kW双馈风力发电实验样机对所提预测虚拟转矩方法进行性能验证。实验结果表明,该方法可实现DFIG系统平滑、无冲击并网,保证了并网接入点的动、稳态电能品质。     

A flexible power control strategy for rotor-side converter of DFIG under unbalanced grid voltage sags

Doubly fed induction generator (DFIG) is widely applied in variable-speed wind energy conversion system. The disconnection of a substantial amount of DFIG may arouse the instability problem of power system, thus wind power generators have to remain connected during short-time grid faults. As a result, the voltage sag will lead to overcurrent and overvoltage in the rotor winding of a DFIG, moreover the unbalanced voltage sags will also cause serious fluctuations in its electromagnetic torque and output power. This paper studies the relationship of the stator instantaneous powers with the three-phase stator voltage and rotor current of a DFIG under unbalanced grid voltages. A generalized formula of current reference for the rotor-side converter of DFIG is constructed by introducing continuous adjustment coefficients. Meanwhile, the analytical equations of rotor peak current, stator active and reactive power fluctuations are derived to characterize the operating performance of DFIG. The impacts of adjustment coefficients on DFIG control performance and the feasible region of coefficients restrained by the rotor current constraint are discussed. In consideration of the rotor current limit, the flexible power control strategy for DFIG in unity power factor mode (UPFM) and reactive power supporting mode (RPSM) is presented. The correctness of proposed method is verified by simulation and experiment tests of single-DFIG and multi-DFIG systems.     

转子感应电势定向的双馈电机风力发电系统研究

考虑风电系统的工况特点,给出了一种双馈电机的无速度传感器的控制方法,在控制中只需检测转子侧电流电压,转子感应电势定向中应用了线性相位有限长脉冲响应数字滤波器(FIR),在同步速附近实施了不同的控制方法,解决了这种无速度传感器控制方法在工程中的应用问题.仿真和实验验证了该方法的正确性和实用性.     

并网型双馈发电机速度控制模式研究

提出了一种基于定子磁场定向的并网型双馈发电机励磁控制模型.有别于传统的功率控制模式,采用所提的速度控制方案,在实现并网型双馈发电机定子端口有功和无功功率解耦控制的同时,还能实现转速的独立控制.另外,带系统耦合量前馈补偿的电流内环控制器设计,能够有效抑制电网电压的波动,并提高系统的动态性能.     

基于差分傅里叶算法和滤波技术的过电压保护装置检测法

为解决火电厂发电机过电压侵害威胁发电机定子及变压器安全的问题，提出一种基于差分傅里叶算法和滤波技术的发电机转子过电压保护装置检测方法。首先，在现场采集发电机过电压保护测试仪的电压结构参数。其次，应用脉冲宽度调制(pulse width modulation,PWM)技术和大功率绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)器件及其驱动技术，解决了传统过电压保护测试仪输出电压和直流输出不够稳定的问题。在此基础上，引入差分傅里叶算法和滤波技术，实现信号的完全输出以及控制的分析、处理、保护等功能，解决了传统过电压保护测试仪信号输出不全以及无法滤波的问题。最后，选取不同电厂机组励磁系统进行过电压保护试验。试验结果表明，所提方法能有效地完成转子过电压保护校验工作，其电压输出值远小于转子绕组出厂工频试验电压幅值的70%，机组励磁系统转子过电压保护逻辑动作正确，动作电压值符合要求，验证了所设计测试方法的有效性和准确性。