基于风电出力耦合相关性及动态稳定性的电力系统无功补偿配置研究

The wind power generation in our country presents the characteristics of large-scale multi-integration and long-distance transmission. Wind farms in the regional power grid with similar wind source usually perform the coupling correlation of wind power outputs. However, the uncertainty of joint wind power output in wind farms, the deficient description of the transient process voltage stability constraint and low voltage ride through (LVRT) constraint lead to the insufficient allocation of reactive power compensation. This project will focus on allocation of reactive power compensation considering the coupling correlationship of wind power output and the dynamic stability operation of power system. Based on the mixed Copula theory, the possibility density function of joint wind power generation will be investigated, and the typical joint wind power output scenarios are obtained by fuzzy cluster method. Multi-objective reactive power allocation optimization will be carried out for the steady-state system with typical joint wind power output scenarios, and the type selection and capacitor ratio index of different reactive power devices will be proposed for wind power plants. On this basis, the mathematical expression of the power system transient process stability constraints and wind power LVRT constraint will be investigated, and allocation of the enhanced reactive power with dynamic response characteristics will be studied. As a result, the step-up allocation strategy of reactive power devices can be realized with the satisfaction of voltage fluctuation constraint caused by joint wind power output fluctuation and corresponding dynamic stability constraints. The research results of this project will provide theoretical basis and technical support for the reactive power allocation of power system with multiple-integration of large-scale wind farms.

我国风力发电呈现大规模多点集群接入、远距离输送的特点，风源相近的风电场间存在风电出力耦合相关性特征。但风电联合出力典型场景、暂态过程电压稳定性约束及风电场低电压穿越约束刻画的不完善，使得无功补偿设备存在配置不充分问题。本项目重点研究考虑风电出力耦合相关性及动态稳定性的电力系统无功补偿配置问题。基于混合Copula理论研究风电场联合出力概率分布，并采用不等概率区间划分法提取风电联合出力典型场景。对考虑风电联合出力典型场景的稳态运行系统进行多目标无功补偿配置研究，并提出风电场内无功补偿设备选型配比指标。通过提出系统暂态过程稳定性约束及风电场低电压穿越约束数学表达，研究具有动态响应特性的无功补偿设备增配方案。通过递进式的配置方式，实现适应电网稳态运行条件下风电联合出力波动影响，并满足系统动态稳定性约束的无功补偿配置。本项目研究成果将为含多风电场电力系统无功补偿配置问题提供理论依据和技术支持。

地区风电场出力的相关性会导致连接有多个大型风电场的电网运行风险增加。建立相关性模型并以此为基础得到典型场景可以对电网运行情况进行简化，为进一步的优化调度等奠定基础。从风电场获取的原始数据主要有风速数据和实际并网有功数据两种，在总结了在此类研究中使用风速或出力数据的情况以及这两种数据优缺点之后，通过实际算例比较了采用风速数据作为原始数据进行风电场相关性描述的多种思路，并提出了一种copula函数的选型方法和针对不同待拟合模型判断拟合优劣的方法。对比了基于风速、实际风电出力和计算风电出力得到的风电场出力典型场景。.在此基础上，考虑稳态运行情况下的电力系统无功规划模型，基于相关性典型场景，通过概率潮流的方法得到各节点越限概率，从而确定无功补偿的选点位置，并进一步利用通过优化模型获得无功补偿容量。在稳态运行情况无功补偿的前提下，考虑含多风电场接入的电力系统的暂态稳定约束，建立风电机组、火电机组、SVC等动态设备的动态模型，并引入隐式梯形积分法，将优化模型设计为含微分-代数方程约束的最优化模型，求解最优化模型得到SVC的补偿位置及其最优补偿容量。最后利用时域仿真技术进行分析校核。项目的研究工作达到了预期的研究目的，验证了方法的可行性。