不确定条件下计及线路保护动作特性的电压暂降频次评估

Voltage sag frequency assessment considering action characteristics of line protection in uncertain conditions

线路保护的动作时限将直接影响电压暂降的重要指标之一——持续时间。针对线路发生故障的情况,对不同动作时限特性的线路保护装置对电压暂降幅值与持续时间的影响展开了研究。计算线路单端跳闸而故障未消除时的多级电压暂降幅值,并根据线路保护的动作特性和故障位置确定电压暂降幅值区间以及不同线路、相同电压暂降区间内的电压暂降持续时间。基于蒙特卡罗模拟法研究不确定条件下的故障信息概率模型,结合保护动作特性对电压暂降幅值及持续时间的影响提出了不确定条件下的计及线路保护动作特性的电压暂降频次评估计算模型,同时考虑故障信息随机性及线路上不同保护类型动作特性对目标节点进行分析,给出包含电压暂降持续时间信息的年均预期电压暂降频次。标准IEEE 14节点系统的仿真结果证明了所提计算方法的正确性和有效性。

The action time of line protection directly affects one of the important indexes of voltage sag ： duration time. Aiming at the condition of line faults, the effects of different action time characteristics of line protection devices on the voltage sag amplitude and duration time is studied. The multi-level voltage sag amplitudes are calculated when the protection device at single-terminal transmission line is tripped while the fault is not eliminated. The interval of voltage sag amplitude and voltage sag duration time of different lines in the same voltage sag interval are determined according to the action characteristics of line protection and fault location. The statistical model of fault information in uncertain conditions is established based on Monte Carlo simulation method and the calculation method of voltage sag frequency assessment considering action characteristics of line protection in uncertain conditions is proposed, considering the effects of action time characteristics of protection on voltage sag amplitude and duration time. The objective node is analyzed and the average annual expected voltage sag frequency including the information of voltage sag duration time is calculated, considering the randomness of fault information and action characteristics of different types of line protection. Simulative results of standard IEEE 14-bus system verify the validity and efficiency of the proposed calculation method.