中文摘要：

基于中压配电网闭环设计、开环运行的特点，以及元件电压降落、功率损耗及树状网络潮流分布的特点，推导出了节点电压、支路传输功率与支路阻抗的关系。在节点负荷矩基础上推导出了计算和修正节点负荷矩的等值阻抗和等值功率计算公式；提出了配电网故障解析中负荷转移后的电压估计模型、送端馈线潮流估计模型和受端馈线潮流估计模型，提高了可靠性评估中元件故障状态下潮流计算的效率。以分块链表简化配电网的结构并给出分块负荷削减的模型，实现了计及潮流约束的配电网可靠性评估。IEEE 33节点系统和工程算例仿真表明，文中提出的负荷削减模型与潮流估算模型相结合可快速、准确地实现中压配电网的可靠性计算，具有较高的工程实用价值。

英文摘要：

According to and open loop operation the features of closed-loop design of medium voltage distribution network and its properties such as voltage drop on component, power loss and power flow distribution in treelike network, the relation among nodal voltages, transmitted powers in branches and branch impedances is deduced. On the basis of defining nodal load moment, the formulae to calculate and modify equivalent impedances and equivalent power of nodal load moments are given; the models for voltage estimation, feeder power flow estimation at sending end and feeder power flow estimation at receiving end after load transfer during fault analysis are proposed, thus the efficiency of power flow calculation in reliability estimation under faulty component can be improved. The structure of distribution network is simplified by section linked list and the section load-shedding model is given to implement reliability estimation of distribution network in which the power flow constraints are taken into account. Verifying by simulation results of IEEE 33-bus system and engineering cases, it is proved that by means of combining the proposed load shedding model with power flow estimation model, the reliability calculation of distribution network can be precisely implemented, therefore the proposed model and method are practicable in engineering.