风电高渗透电力系统戴维南等值参数解析方法研究

This proposal aims to propose an analytical method, based on the multi-port equivalent theory, to calculate Thevenin's equivalent parameters of power systems with high penetration of wind power, with the application to the voltage control of the point of common coupling connecting wind farms to power grids. Firstly, this project is to simulate the impacts of various factors, including turbine types, wind farm structures, reactive power regulators, active/reactive power outputs and wind speed randomness, on Thevenin's equivalent parameters of wind farms and to analyze their relationships, and further establish the analytical model and solution method to calculate Thevenin's equivalent parameters of wind farms. Secondly, the impacts of various factors, including wind speed randomness and wind power penetrating level, on Thevenin's equivalent parameters of power systems and their assessment accuracies will be studied to explore the related physical mechanisms. Thirdly, through deep studies and analysis for the electrical characteristics of a variety of high nonlinear and time-varying elements, an analytical expression is expected to represent their impacts on Thevenin's equivalent parameters of power systems, and an analytical model and solution method could be further proposed to calculate Thevenin's equivalent parameters of power systems with high penetration of wind power. Finally, based on the proposed analytical equivalent models, this project is to develop the analytical sensitivities of a variety of reactive power regulations in wind farms or power grids to the voltage at the point of common coupling, and to further formulate a piecewise linear multi-level optimization model and stepwise solution method for online control of the voltage at the point of common coupling.

本项目拟基于多端口等值理论，研究风电高渗透电力系统戴维南等值参数解析方法及基于戴维南解析等值的风电并网点电压控制问题。首先，模拟风机类型、风场结构、无功调控、风速随机性、有功无功出力等因素对风电场戴维南等值参数的影响，研究和解析它们与风电场戴维南等值参数之间的关系，进而建立风电场戴维南等值参数的解析模型与计算方法。然后，研究分析风电的渗透率、风速的随机性等因素对电力系统戴维南等值参数及其评估精度的影响，挖掘其物理机制。其次，通过对系统中各种强非线性和强时变性因素电气特性的研究和解析，提出显式表述它们对戴维南等值参数影响的方法，进而建立风电高渗透电力系统戴维南等值参数的解析模型与计算方法。最后，基于戴维南解析等值模型，研究和提出风场侧和电网侧的无功调控措施相对于风电并网点电压的解析灵敏度，建立具有分段线性、逐段优化特点的分层优化模型和方法，实现风电并网点电压的在线控制。

戴维南等值是化简复杂电路的有效方法，然而由于电力系统的时变性和非线性，导致如何快速准确地评估电力系统的戴维南等值参数一直是有待突破的技术难题。风电等间歇性能源的大规模接入，更加剧了其挑战性。本项目旨在通过多端口等值理论，从网络解析角度，研究风电高渗透电力系统戴维南等值参数的解析模型与方法及风电并网点的电压控制方法。. 提出了适用于计算风电场等值阻抗的网络解析方法及风电场“类戴维南”等值模型的参数计算方法。推导了故障穿越全过程风电场功率行为的解析表达式，提出并验证了基于功率全过程故障穿越行为校正的改进单机等值方法。该方法原理明晰，计算简单，所需参量少，易于被工程技术人员理解和掌握。. 研究了传统非线性电路戴维南等值参数辨识方法存在的问题及机理，发现基于最小二乘的传统方法得到的戴维南等值阻抗不唯一，其值除了和扰动源的位置和扰动大小有关外，还与扰动的有功和无功比有关；但其具有上下限，且在崩溃点汇聚为一个值。. 提出了一种基于单时刻测量数据的戴维南等值参数计算方法。该方法无需多时刻测量数据，从根本上克服了由于系统侧波动而给传统戴维南等值计算造成的影响，但如何减少其对多节点数据的需求量以增强其实用性，仍有待进一步突破。. 研究了多端口网络等值与戴维南等值的关系，从网络解析角度给出了非线性电路戴维南等值参数的解析表达式，将可描述OXL作用下的发电机模型应用到多端口网络等值中，使得改进后的多端口等值网络能够有效计及发电机由AVR向OXL转换的动态变化。. 基于戴维南解析等值电路，提出了识别电源节点间的耦合关系和电源节点对负荷节点的电压控制灵敏度的解析指标，以及基于节点耦合关系的无功电压递归切割分区方法。通过网络解析手段，建立了识别节点电压薄弱性的解析指标，能够解析地识别降低节点电压薄弱性的控制措施，实现电压稳定的在线监视与控制，而且将之用于了解决风电接纳能力评估与优化规划问题。