大规模风电接入弱交流电网的机网交互作用机理与控制研究

In the condition of connecting large scale wind power into weak AC grid, the current wind generator control strategies which are designed based on an assumption of strong grid connection condition are very difficult to be adapted, and the closely coupled interactions between wind generators and power grid are becoming more severe. It is very significant in theory and in practice to study the interactions between wind generators and power grid and related control strategies concerning the connection of large scale wind power into weak AC grid. This project focuses on the key scientific issues related to operation and control of connecting large scale wind power into weak AC grid, and conducts the relevant studies to explore the dedicated wind generator models and analytical methods, to reveal the new fault characteristics such as voltage phase jump as well as their impacts on wind generator control strategies and the control coordination during normal operation and fault ride through condition, to analyze the power oscillation as well as damping characteristic of power system integrating large wind power, and the impacts of wind generator controller nonlinearity on system damping, eventually to figure out the interaction mechanism between wind generators and power grid in case of connecting large scale wind power into weak AC grid, and to propose wind power optimized control strategies for improving wind generator fault ride through capability and damping the power oscillation. The project carries out studies in different aspects which consist of model methodology, mechanism analysis as well as control strategies, and will establish theoretical foundation for the research of incorporating large scale wind power into weak AC grid, solve technical problems with regard to guaranteeing a safe operation of grid connection of large scale wind power.

大规模风电接入弱交流电网条件下，现有基于强电网运行环境设计的风机控制技术难以适应，风机集群之间及其与电网之间耦合交互作用突出。研究大规模风电接入弱交流电网的机网交互作用机理与控制具有重要理论和实践意义。本课题以大规模风电接入弱交流电网为研究对象，围绕风电接入弱交流电网运行控制这一关键科学问题，研究相应的风电模型和分析方法；研究电压相位跳变等新的故障特征对风机控制的影响，以及风机正常运行控制与故障穿越控制的策略切换和协调；分析风电并网系统的振荡模式和阻尼特性，以及风机控制非线性对系统振荡特性的影响；最终揭示大规模风电接入弱交流电网的机网交互作用机理，并针对风电故障穿越和风电并网系统振荡特性提出风电优化控制策略。项目从模型方法、机理分析、控制策略几个层面开展研究，为大规模风电接入弱交流电网研究体系奠定理论基础，解决我国大规模风电并网安全运行面临的技术难题。

随着局域电网中风电接入比例升高，大规模风电接入弱交流电网下的运行控制问题逐渐突出。项目围绕大规模风电接入弱交流电网下的机网交互作用，重点针对故障穿越和阻尼振荡技术开展研究，主要工作及其成果包括：.①结合风电机组实际各个物理/控制功能模块，详细描述变流器故障穿越控制策略，基于型式试验数据校核风电机组故障穿越模型参数，并采用短路比作为弱电网评价指标，建立了适应于风电接入弱交流电网故障分析的风电场时域仿真模型；结合风电机组模型各子模块多时间尺度特征，以着重考虑电流内环控制、锁相环的动态特性作为简化条件，建立了适应于小扰动分析的风电并网系统频域阻抗模型。.②揭示了风电并网系统故障穿越过程中机端电压相位跳变特征及其对故障穿越控制能力的影响，提出了一种考虑相位跳变特性的风电机组转子电压直接补偿控制策略；评估了风电接入弱交流电网的故障穿越能力及主要影响因素，提出了考虑弱交流电网条件的风电机组故障穿越控制切换及协调策略，提出了一种故障穿越恢复控制与阻尼控制的协调策略，提出了一种基于虚拟同步控制的风电机组新型故障穿越控制策略。.③分析了风电机组控制器限幅环节对次/超同步振荡形态的影响，揭示了风电并网次同步振荡的多频率响应特征；基于风电并网系统闭环极点稳定性判据，分析了转子电流环控制参数和锁相环参数对闭环极点的参数灵敏度，并根据参数灵敏度分析提出了一种抑制振荡的风电机组控制参数优化以及附加阻尼控制策略；揭示了双馈风电机组与静止无功发生器交互作用原理及其对系统振荡特性的影响，提出了一种双馈风电场与静止无功发生器的协调阻尼控制策略。.项目从模型方法、机理分析、控制策略几个层面开展研究，项目成果为大规模风电接入弱交流电网研究体系奠定了理论基础，对于提高大规模风电接入弱交流电网的运行品质和安全性，具有重要的理论价值和现实意义。