【作者】 赵新；

【导师】 金新民；

【作者基本信息】 北京交通大学 ， 电力电子与电力传动， 2014， 博士

【摘要】 摘要：直驱型风力发电机组因其具有可靠性高、传动效率高、故障穿越能力强、发电机与电网无直接耦合等优点,成为了风电领域重要的发展趋势。近年来,永磁直驱型风电机组成本受永磁材料的价格、储量等因素影响较大,从而使电励磁直驱型风电机组成为直驱型风电机组的又一个发展方向。本文围绕电励磁直驱型风力发电机并网控制技术展开理论研究,对并网逆变器和电励磁同步发电机(electrically excited synchronous generator, EESG)的控制策略进行了研究,取得了以下成果。1.围绕并网逆变器的建模和电流控制性能进行了研究。在并网逆变器静止坐标系和同步旋转坐标系下的动态数学模型的基础上,研究了并网逆变器在同步旋转坐标系下的解耦PI控制和静止坐标系下的PR控制两种典型电流控制策略的特点。利用复矢量分析法对采用不同电流调节器时系统的解耦性能、跟随性能、抗扰性能进行了对比分析。对静止坐标系下基于PR电流调节器时系统的功率解耦性能进行了理论分析,得到了系统的功率耦合关系,并提出了通过改进传统PR调节器实现功率解耦的方法。最后,通过并网逆变器的仿真和实验结果验证了静止坐标系下采用改进型PR电流调节器可以实现系统有功功率和无功功率的解耦控制,改善系统的动态性能。2.对不平衡电网条件下并网逆变器的控制策略进行了研究。利用对称分量法建立了直驱风力发电机系统中并网逆变器在不平衡电网电压条件下的数学模型。针对不平衡电网电压条件下实现并网逆变器与电网同步的问题,提出了一种基于降阶谐振调节器的锁频环(frequency-locked loop based on reduced order resonant controller, ROR-FLL)技术实现电网频率检测及不平衡电压的正、负序分离等,通过仿真和实验验证了ROR-FLL实现正负序分离、谐波及频率检测的可行性。采用提出的ROR-FLL,引入了通用正负序电流指令计算方法,得到了并网逆变器静止坐标系下基于PR电流调节器的不平衡控制策略。最后,提出了一种新型的电流调节器——比例积分降阶谐振(proportion integral plus reduced order resonant, PI-ROR)调节器,并将其应用到不平衡控制系统中进行不平衡电流的控制,得到了一种正向同步旋转坐标系下基于PI-ROR电流调节器的不平衡控制策略,通过仿真和实验验证了系统的稳态和动态性能。3.围绕EESG的建模和磁链观测技术展开研究。建立EESG在静止坐标系、dq同步旋转坐标系和MT轴系下的动态数学模型的基础上,研究了EESG的不同磁链定向方法,给出了气隙磁链定向控制的原理,并设计了矢量控制系统。对EESG矢量控制系统中的磁链观测技术进行了研究,针对基于电压模型磁链观测器中纯积分环节的初始值、直流偏置、积分饱和等问题,提出了一种改进型二阶广义积分器(improved second-order generalized integrator, ISOGI)代替纯积分器,得到了一种基于ISOGI的电压模型磁链观测技术,并对其实现方法及性能进行了分析。最后,通过Matlab仿真和电励磁直驱型风力发电系统实验平台验证了基于ISOGI磁链观测器是可行性,且此方案在风力发电系统要求的频率范围具有较好的稳态及动态性能。4.对电励磁直驱型风力发电机在短时超速情况下的弱磁控制进行了研究。首先,介绍了EESG弱磁控制的原理,规划出了EESG在恒转矩区和高速弱磁区的电流轨迹。其次,对基于动态定子磁链电流补偿的EESG定、转子综合弱磁控制方法的性能进行了分析,并通过仿真和实验进行了验证。接着,针对传统弱磁控制方法存在动态响应慢的问题,提出了两种改进的弱磁控制方案：基于“虚拟阻抗”的定、转子综合弱磁控制方案和基于变M轴电压单电流调节器的定、转子综合弱磁控制方案。最后,通过仿真和实验验证了所提弱磁控制方案能够加快弱磁控制的动态响应,可以应用于电励磁直驱型风力发电系统的短时超速工况下,保证风力发电系统在更宽的速度范围内可靠运行。更多还原

【Abstract】 Direct-driven wind generation system is considered to be an important development tendency in wind generation technology area due to its superiorities of high reliability, high efficiency, good grid fault ride-through ability, etc. Recently, the price and reserves of permanent magnet materials has great influence on the cost of permanent magnet direct-driven wind generation system, and electricity excitation direct-driven wind generation system becomes another development direction. This dissertation gives theoretical study on grid-connected control technology for direct-driven wind generation system. The control strategies of grid-connected inverter (GCI) and electrically excited synchronous generator (EESG) are both discussed comprehensively. Simulations and experiments demonstrate the correctness of the research results. Following are the major research works of this dissertation.Firstly, modeling and current control of GCI have been discussed. The GCI dynamic modeling is established and expressed in the stationary reference frame and synchronous rotating reference frame. Two typical vector control strategies of GCI are realized, which is decoupled PI current control implemented in the synchronous reference frame, and PR current control in the stationary reference frame. Using complex vectors, the vector control system based on different current regulators are analyzed from three aspects of decouple control, tracking performance and disturbance rejection performance. The power decouple control in stationary frame is analyzed comprehensively, and a new method is provided for achieving the power decoupling. Simulation and experimental results verify that the improved PR current regulator can realize the power decoupling control and increase the dynamic performance.Secondly, the control strategy of GCI under unbalanced grid voltage has been emphasized. Dynamic modeling of GCI applied on unbalanced voltage conditions is established using symmetrical component method. To synchronize at the fault condition, a novel frequency-locked loop technology based on the reduced order resonant controller (ROR-FLL) is presented. The ROR-FLL can accurately and rapidly extract the positive-negative sequences and frequency from unbalanced voltage, and the simulation and experimental results show its feasibility and excellent transient performance. An unbalanced control strategy in stationary reference frame is presented using ROR-FLL and generalized reference current generation method. A novel controller, proportion integral plus reduced order resonant (PI-ROR) controller, is proposed, which can be used in the unbalanced control system to control the unbalanced current. The novel unbalanced control method based on PI-ROR controller can realize the unbalance control targets with excellent transient performances.Thirdly, modeling and flux observer of EESG have been discussed. The dynamic modeling of EESG is created and expressed in the stationary reference frame, dq synchronous rotating reference frame, and MT synchronous rotating reference frame, respectively. The different flux oriented methods are discussed, and the working principle and system design method of air-gap flux oriented vector control are analyzed. The flux observer in EESG vector control system is emphasized based on voltage model of EESG. Then, an improved second-order generalized integrator (ISOGI) which could eliminate the DC bias and integral windup is proposed to replace pure integrator, and a new flux observer based on ISOGI is achieved. Simulation and experimental results show the feasibility of ISOGI flux observer, and this method has excellent steady and transient performance in the frequency range of electrically excited direct-drive wind power system.Fourthly, the flux weakening control strategy of EESG under short-time overspeed in the wind power system has been discussed. The working principle of flux weakening control is analyzed, and the current trajectory of EESG is programmed in constant torque and the flux weakening operation region. Then, the performance of stator and rotor side compositive flux weakening control method of EESG based on dynamic stator flux current compensation is discussed and verified by simulation and experimental results. In order to achieve better flux weakening dynamic response, two improved stator and rotor side compositive flux weakening control methods based on virtual impedance and single current regulator has been proposed. Simulation and experimental results validate the feasibility of these control methods, and the wind power system can operate in wide speed range.更多还原