【作者】 付超；

【导师】 石新春； 王毅；

【作者基本信息】 华北电力大学 ， 电力电子与电力传动， 2012， 博士

【摘要】 随着风力发电在电网中的渗透率不断增加,其间歇性、随机性等特点对电网的影响日益显著,无论是风电大规模集中并入电网,还是风电小规模分散式接入电网,均对电网的运行和控制提出了严峻挑战。目前,风电并网区域的无功电压问题尤其突出,深入研究风电机组并网的无功控制技术,对提高电网接纳风电能力和保证电网安全稳定运行具有重要意义。本文从挖掘双馈风电机组的无功控制潜力、实现多风电场接入区域电网的无功优化调度的角度,研究风电并网的无功和电压优化协调控制策略,并搭建风电并网控制的数模混合仿真系统,对所提出的控制方案进行实验验证。本文主要的研究内容及成果如下：(1)建立了三相静止坐标系下和同步旋转坐标系下双馈风力发电机及PWM换流器的数学模型；推导了双馈风电机组转子电压、电流与DFIG定子输出功率之间的关系以及DFIG定、转子间的功率关系；分析了DFIG风电机组的控制策略,建立了双PWM换流器矢量控制模型。(2)基于上述理论分析,研究了转子换流器、定子绕组、网侧换流器以及机端电压等因素对DFIG的无功功率极限的影响；针对双馈风电机组自身的优化运行控制,深入研究全补偿控制、最小转子电流控制、最小损耗控制和恒转子电流控制四种控制策略的特点,并推导转子电流参考值的计算方法；针对DFIG对电网的无功补偿控制,提出了基于无功电流裕度的转子侧换流器优先、网侧换流器优先以及二者比例分配无功三种协调控制策略,以实现对换流器容量的充分利用。(3)提出了一种多风电场并网的区域电网无功电压优化协调控制策略,该控制策略综合考虑系统电压质量和网损的优化,并采用遗传算法进行优化求解。利用区域电网的无功电压灵敏度和无功网损灵敏度信息对基于潮流计算的遗传算法进行改进,提高了优化算法的计算速度,进而增强了无功协调控制的实时性。在上述研究基础上,提出了一种基于超短期风电功率预测和无功电压优化的风电场并网在线预警与无功优化控制系统的设计方案,利用PowerFactory软件提供的引擎模式功能和DGS接口进行二次开发,构建了与电网EMS的数据接口,实现了以PowerFactory软件为计算核心的风电并网安全预警与无功优化控制系统。(4)针对研究风电并网控制相关问题的需要,提出了一种基于NI-PXI平台的数模混合仿真系统实现方案,通过对该混合仿真系统简化模型的稳定性分析,讨论了实现该方案对接口算法和参数的基本要求,并提出了实时信号同步控制策略以解决数字仿真系统与物理仿真系统反馈电压信号同步问题。在上述研究的基础上,构建了实际的数模混合仿真系统,对风电并网功率控制以及多风电场并网无功优化协调控制进行了数模混合仿真实验,通过实验验证了所提混合仿真方案的可行性以及控制策略的有效性。更多还原

【Abstract】 With wind power penetration increasing, the effects on power system become more significant due to the uncertain nature of wind power, and the serious challenges at power system security operation and control are encountered whether wind power is integrated into grid as large-scale centralized mode or small-scale decentralized mode. At present, since the reative power and voltage issues emerged at the regional grid with wind power, it is necessary for increasing the capbility of accepting wind power and ensuring power system operation security. For utilizing the reactive power control of DFIG and optimizing the reactive power of the regional grid with multi wind farms, the reacitve power and voltage optimal coordinated control strategy is studied, and a digital/physical hybrid simulation system for wind power control is constructed to verify the proposed contro strategy. The main contents and contributions are as follows:(1) The mathematical models of DFIG and PWM converter under three-phase stationary coordinate and the synchronous coordinate are constructed, and the relationship is derived in detail which is between the rotor voltage, current and output power of DFIG stator in steady state conditions. The general control strategy for DFIG wind turbine is introduced, and the control model for dual PWM converters were built up.(2) Based on the theoretical analysis above, it was analyzed in particular that the impact on DFIG reactive power limit caused by design of rotor converter, stator winding, the grid side converter and terminal voltage factors, etc. For the optimal operation control of the DFIG, it were studied deeply that the characteristics of four control strategy including the full compensation control, the minimum rotor current control, the minimum power loss control, and the constant rotor current control. The algorithm for calculating the rotor current reference values were given. According to control of reactive power compensation, three coordinated control strategies are proposed which are based on RSC priority, GSC priority, and proportional dispatching, so as to achieve fully use of converter capacity.(3) A coordinated control strategy of reactive power optimization for multi wind farms integrated into regional grid is proposed, which considered the voltage quality and power loss synthetically, and optimal solution is solved via genetic algorithm. An improved genetic algorithm is proposed which utilized the reactive power sensitivity to voltage and to power loss. As results, the optimal computing speed of genetic algorithm and the real-time performance of the coordinated control are improved significantly. Supported by above studies, a design scheme of online pre-alarm and reactive power optimal control system for wind power grid integration is proposed that based on the ultra-short-term wind power prediction and reactive power optimization. Secondary development is performed which utilized the engine mode supported by PowerFactory software and DGS interface, and the data interface is developed which used for exchanging data with EMS. Finally, the pre-alarm and reactive power optimal control system is realized which takes PowerFactory engine as the computing core.(4) According the requirement of study on wind power control, a design scheme for DPHS is proposed which is based on the NI-PXI platform. The stability of the proposed scheme is analyzed via using the simplified model of the DPHS, and the base demands for the interface algorithm and parameters are discussed. A control strategy for synchronizing grid voltage signal between digital simulation and physic simulation is proposed. Based on the above study, a real DPHS system is established, on which wind power control and coordinated control for multiple wind farm are performed, and the validity of the proposed scheme and the feasibility of the control strategy are verified.更多还原