风力发电用双馈感应发电机控制策略的研究

该文从并网风力发电系统的基本特性出发，在分析双馈感应电机数学模型及其定子磁链定向矢量控制的基础上，论证了其有功功率和无功功率的独立控制的可行性并给出了PID双闭环控制方案。利用Matlab／Simulink平台，仿真研究并验证了该控制方案的正确性，对实际软硬件系统的设计与调试具有一定的指导意义。     

变速恒频双馈风力发电机有功、无功解耦控制研究与实现

双馈发电机有功功率、无功功率解耦控制是变速恒频风力发电系统的关键技术,在分析双馈发电机有功功率、无功功率解耦控制规律的基础上,给出了基于定子磁场定向控制策略的实现方案,然后利用Matlab工具对该控制方案进行了仿真研究,最后设计和构造了基于TI公司MS320F2407DSP的变速恒频双馈风力发电机有功功率、无功功率解耦控制实验系统,仿真和实验结果表明该控制策略能够有效地实现双馈发电机功率的解耦控制,为兆瓦级变速恒频双馈风力发电机组励磁变换器的研制奠定了基础。     

并网故障下双馈感应风力发电系统的改进控制策略研究

介绍在并网故障下对双馈感应风力发电系统改进的控制策略研究。并网故障分为对称故障和不对称故障,在不对称故障情况下,当电网电压频率为60 Hz并且电机转速接近同步速时,在双馈感应风力发电机的转子中将会出现接近于120 Hz的转子电流主要谐波;在对称故障下,定子电压有一个瞬间跌落,从而会在转子中导致过电流、过电压、过转速的出现。该文中转子侧变频器(RSC)主要用于抑制在并网故障下转子中出现的谐波分量或过电流等现象;网侧变频器(GSC)则用于抑制变频器之间直流电容电压中出现的谐波,以维持直流电容电压恒定。所提出改进控制策略可更好地抑制并网故障,改善整个双馈感应风力发电系统的控制性能,并使用Matlab/Simulink仿真验证了控制效果。     

转子侧采用直接功率控制的双馈风力发电系统

在研究双馈感应发电机(DFIG)数学模型的基础上,分析了对称电网条件下DFIG定子侧输出有功、无功功率的组成,对转子侧采用了一种新颖的直接功率控制(DPC)方法控制变换器的工作状态,实现对定子端输出的有功、无功功率的控制,较好地实现了二者的解耦。基于Matlab建立了DFIG风力发电系统仿真模型。仿真结果显示,所采用的方案具有快速的动态响应功能和良好的控制效果。     

恒速和双馈感应风电机的稳定性研究

随着并网风电容量的增大,风电在电力系统中比重的增加,为研究风力发电系统的稳定性,采用电力系统仿真软件DIgSILENT/PowerFactory对恒速和双馈感应两种异步风电机进行建模仿真,分析其在短路故障时不同风电机组及电气参数对系统恢复稳定的影响。结果表明:双馈感应风电机的故障动态响应比较敏感,具有明显优势。     

恒速和双馈感应风电机的稳定性研究

随着并网风电容量的增大,风电在电力系统中比重的增加,为研究风力发电系统的稳定性,采用电力系统仿真软件DIgSILENT/PowerFactory对恒速和双馈感应两种异步风电机进行建模仿真,分析其在短路故障时不同风电机组及电气参数对系统恢复稳定的影响。结果表明:双馈感应风电机的故障动态响应比较敏感,具有明显优势。     

双馈风力发电矩阵式变流系统动态解耦研究

针对背靠背双PWM变流器励磁的双馈风力发电存在功率因数低以及传统矢量控制策略存在动态解耦性能不佳的问题,提出采用非线性控制策略的双级矩阵变换器励磁双馈风力发电系统解决方案。通过输入输出线性化解耦控制理论,将双馈风力发电系统精确为一个线性化系统,采用矢量坐标变换和非线性控制策略,实现对双馈风力发电系统高性能解耦控制,提高了系统的动态性能,提升了系统的响应速度。结合系统各部分的控制目标,搭建整个系统的仿真模型,仿真结果表明采用双级矩阵变换器及其非线性控制策略可实现双馈风力发电有功和无功功率的解耦控制和最大功率点跟踪等性能指标,达到风力发电控制的要求。     

双馈风电系统高电压穿越的节能控制策略

在研究双馈风力发电系统高电压穿越的节能控制问题的过程中,考虑到外部风力环境变化较大,需保持变换器的稳定性节能控制。传统节能控制方法不仅动态及稳态性能差,而且节能控制策略相对复杂。为了提高节能控制效果,提出采用串联网侧变换器的双馈风电系统高电压穿越的节能控制策略,向串联网侧变换器的控制向电机定子侧和电网间添加合理的控制电压,按照电网电压定向的同步旋转,给出d-q轴系下SGSC的电压控制方程,保持DFIG定子端电压不变,过滤DFIG定子磁链中的暂态直流分量。当双馈风电系统电压及电流均不超限时,对转子侧变换器和并联网侧变换器的输出电压矢量进行节能控制,使双馈风电系统为电网提供最大程度的无功支持,快速恢复电网电压。仿真实验结果表明,所提策略具有很高的节能控制性能。     

改进的双馈风电机组故障穿越控制策略研究

基于传统矢量控制技术,该文提出一种改进的矢量控制技术来抑制双馈感应电机故障期间的转子过电流,以提高双馈风电机组故障穿越能力。从分析传统矢量控制技术入手,提出一种改进的矢量控制技术,其主要特点是反映定子电压瞬态对转子电流的影响,但并未增加控制的复杂程度。从理论的角度对所提方案能提高双馈风电机组故障穿越能力的机理进行深入分析。最后,对基于PSCAD/EMTDC软件环境下搭建的2 MW双馈风电机组模型进行仿真研究。仿真结果表明所提方案能有效抑制双馈感应电机故障期间的转子过电流,从而提高双馈风电机组的故障穿越能力。     

双馈风力发电系统最大风能追踪控制

在分析风力机功率特性和DFIG运行特性的基础上,通过对双馈机转速控制进行最大风能追踪具体过程的深入研究,提出一种基于最大风能追踪的双馈电机有功、无功功率的解耦控制方法。建立了基于发电机定子磁链定向矢量控制的双馈风力发电系统最大风能追踪系统模型,并利用PSCAD／EMTDC对其进行仿真,结果验证了控制策略的正确性。     

大型变速恒频风力发电机组建模与仿真

基于SIMULND技术,利用双馈感应发电机、风力机、电压型变流器、电压型逆变器的数学模型建立了相应的仿真模型;并对定子侧直接与50Hz电网连接,转子侧连接AC/DC/AC变流器的典型变速恒频风力发电系统进行了仿真验证.几个单独的风力发电系统子系统可以通过级联的方式构成大型风力发电场来模拟整个电网的运行情况.仿真结果表明,DFIG仿真模型的正确性和验证大型风电场的有效性.     

Integrated power characteristic study of DFIG and its frequency converter in wind power generation

A doubly fed induction generator (DFIG) is a variable speed induction machine. It is a standard, wound rotor induction machine with its stator windings directly connected to the grid and its rotor windings connected to the grid through a back-to-back AC/DC/AC PWM converter. The power generation of a DFIG includes power delivered from two paths, one from the stator to the grid and the other from the rotor, through the frequency converter, to the grid. The power production characteristics, therefore, depend not only on the induction machine but also on the two PWM converters as well as how they are controlled. This paper investigates power generation characteristics of a DFIG system through computer simulation. The specific features of the study are (1) a steady-state model of a DFIG system in d–q reference frame, (2) a simulation mechanism that reflects decoupled d–q control strategies, (3) power characteristic simulation for both generator and converter, and (4) an integrative study combining stator, rotor and converter together. An extensive analysis is conducted to examine integrated power generation characteristics of DFIG and its frequency converter under different wind and d–q control conditions so as to benefit the development of advanced DFIG control technology.     

Performance of PI controller for control of active and reactive power in DFIG operating in a grid-connected variable speed wind energy conversion system

Due to several factors, wind energy becomes an essential type of electricity generation. The share of this type of energy in the network is becoming increasingly important. The objective of this work is to present the modeling and control strategy of a grid connected wind power generation scheme using a doubly fed induction generator (DFIG) driven by the rotor. This paper is to present the complete modeling and simulation of a wind turbine driven DFIG in the second mode of operating (the wind turbine pitch control is deactivated). It will introduce the vector control, which makes it possible to control independently the active and reactive power exchanged between the stator of the generator and the grid, based on vector control concept (with stator flux or voltage orientation) with classical PI controllers. Various simulation tests are conducted to observe the system behavior and evaluate the performance of the control for some optimization criteria (energy efficiency and the robustness of the control). It is also interesting to play on the quality of electric power by controlling the reactive power exchanged with the grid, which will facilitate making a local correction of power factor.     

双馈风力发电系统最大风能追踪控制的研究

在分析了风力机功率特性和DFIG运行特性的基础上,通过对双馈机转速控制进行最大风能追踪具体过程的深入研究,提出了一种基于最大风能追踪的双馈电机有功、无功功率的解耦控制方法。建立了基于发电机定子磁链定向矢量控制的双馈风力发电系统最大风能追踪系统模型,并利用PSCAD/EMTDC对其进行仿真,结果验证了控制策略的正确性。     

DFIG sliding mode control fed by back-to-back PWM converter with DC-link voltage control for variable speed wind turbine

This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-(PI) controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.     

Power decoupling control of DFIG rotor-side PWM converter based on auto-disturbance rejection control

In this paper, double PWM converter AC excitation system of the variable speed constant frequency doubly fed induction generator (DFIG) for wind power generation is taken as the research object. At present, most vector control systems of rotor-side PWM converter adopt feedforward compensation to realize the purpose of power decoupling control. The decoupling effect is greatly affected by the power changes. A power decoupling control strategy based on auto-disturbance rejection control (ADRC) is proposed. The decoupling control between active power and reactive power is realized by observing the coupling term and the total disturbance of the d-axis and q-axis components of the stator current and the stator voltage with the extended state observer and compensating. Simulation analysis and experimental test show that, on the basis of vector transformation, the rotor-side PWM converter power decoupling control based on ADRC has a small overshoot and fast dynamic response when tracking the change of wind turbine input power, which can achieve the decoupling control between active power and reactive power well. The system has strong robustness and adaptability.     

Comparative study on the performance of control systems for doubly fed induction generator (DFIG) wind turbines operating with power regulation

As a result of the increasing wind power penetration on power systems, the wind farms are today required to participate actively in grid operation by an appropriate generation control. This paper presents a comparative study on the performance of three control strategies for DFIG wind turbines. The study focuses on the regulation of the active and reactive power to a set point ordered by the wind farm control system. Two of them (control systems 1 and 2) are based on existing strategies, whereas the third control system (control system 3) presents a novel control strategy, which is actually a variation of the control system 2. The control strategies are evaluated through simulations of DFIG wind turbines, under normal operating conditions, integrated in a wind farm with centralized control system controlling the wind farm generation at the connection point and computing the power reference for each wind turbine according to a proportional distribution of the available power. The three control systems present similar performance when they operate with power optimization and power limitation strategies. However, the control system 3 with down power regulation presents a better response with respect to the reactive power production, achieving a higher available reactive power as compared with the other two. This is a very important aspect to maintain an appropriate voltage control at the wind farm bus.     

Direct power control of DFIG based on discrete space vector modulation

This paper presents a new direct power control (DPC) strategy for a double fed induction generator (DFIG) based wind energy generation system. Switching vectors for rotor side converter were selected from the optimal switching table using the estimated stator flux position and the errors of the active and reactive power. A few number of voltage vectors may cause undesired power and stator current ripple. In this paper the increased number of voltage vectors with application of the Discrete Space Vector Modulation (DSVM) will be presented. Then a new switching table in supersynchronous and subsynchronous frames will be proposed. Simulation results of a 2 MW DFIG system demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, machine parameters, and wind speed.