基于多状态模型的含微网的配电系统可靠性评估

Due to the energy, climate, environmental protection requirements, distributed generation(DG) connected to distribution network has become an inevitable trend, the microgrid technology is an effective method of accomondating distributed generation. Active distribution network with microgrid will become an important characteristic of future smart grid, and its quantitative reliability assessment is a difficult technical problem needing to be solved urgently. Considering the diversity and uncertainty of DG and load, the optimal discretization method of continuous random variable, such as wind power, photovoltaic power generation, heat load and power load, is poposed, and their multi-state reliability models are established, their correlation is expressed by using Copula function. Combined with the power regulation of energy storage element, the multi-state equivalent models of islanded microgrid and grid-connected microgrid can be established, based on unified generating function(UGF) of multi-state system, Markov state transition technology and multi-state equivalent models of DG and Load. The topology analysis method of distribution system with microgrid is studied. Considering the supplying power of isolated microgrid and the assisting load transfer of grid-connected microgrid when the fault occurs, an accurate and efficient reliability evaluation method of distribution network with microgrid is put forward by using the multi-state equivalent models of microgrid and reachability analysis technique of graph theory. By the typical example simulation and comparative analysis with other methods, the effectiveness of the proposed models and methods is verified.

由于能源、气候、环保需求，分布式电源接入配电网已成必然趋势，微网技术是消纳分布式发电的有效手段，含微网的配电系统将成为未来智能电网的重要形态特征，对其进行精确快速的可靠性定量评估是迫切需要解决的技术难题。本文考虑微网中分布式电源和负荷的的多样性、不确定性，研究风力发电、光伏发电、热负荷、电力负荷等连续随机变量离散化的优化方法，建立其多状态可靠性建模，并利用Coupla函数进行相关性表达；以分布式电源和负荷多状态可靠性模型为基础，利用多状态系统通用生成函数、Markov状态转移技术，结合储能元件功率调节，建立孤岛微网和并网微网的多状态可靠性等效模型；研究含微网的配电系统拓扑分析方法，基于微网等效和图论可达性分析，考虑故障时孤岛微网供电及并网微网协助负荷转供，提出含微网的配电系统可靠性分解协调快速评估方法，通过典型算例仿真与方法比较分析验证所提出模型和方法的有效性。

微网技术是消纳风力、光伏分布式发电的有效手段，含微网的配电系统将成为未来智能电网重要形态特征，对其进行精确快速的可靠性评估是迫切需要解决的技术难题。. 针对风力、光伏分布式电源功率模拟的需求，提出了风速、光照随机变量概率密度函数建模方法，该方法以均值、方差、偏度、峭度、信息熵等高阶统计量偏差最小为准则，建立风速分布参数k和尺度系数c、光照强度形状参数α、β的优化模型，采用遗传算法进行模型求解。考虑风力、光伏及负荷的相关性，提出了根据曲线距离和Kendall相关系数的Copula函数优选方法，提出了基于Copula理论的联合相关抽样法。. 考虑设备组成、结构布局、连接方式、能源转换特性以及自然资源的不确定性，提出了风力、光伏发电系统多状态可靠性建模方法。基于通过生成函数法和马尔科夫状态转移技术，提出了微网净功率多状态等值建模方法。采用合并同类项法、比例均摊法、K-means聚类法的组合状态削减技术，有效避免了微网多状态建模过程中通用生成函数运算产生的状态爆炸。. 针对可再生能源随机波动对自治微网旋转备用容量的要求，提出了自治微网旋转备用概率预测充裕性评估方法，采用概率性指标电量不足期望(EENS)和电量过剩期望(EENU)作为系统旋转备用充裕性的评估指标，给出了自治微网旋转备用概率预测充裕性评估流程。. 将含微网的配电网可靠性评估指标体系从“节点-系统”扩展到“节点-分区-系统”，根据“微网自治孤岛、微网联合孤岛、微网协助转供”提出评估指标。针对蒙特卡洛模拟法可靠性评估耗时过长的问题，建立了同时反映运行状态及荷电状态的储能多状态建模，采用多状态孤岛后果分析法评估孤岛微网的负荷停电状态，根据可达性分析和微网多状态等值提出了适用于含微网配电系统的可靠性的快速高精度评估算法。. 通过本课题的研究，形成了微网多状态建模及基于多状态模型的含微网配电系统可靠性评估理论与技术体系。