融冰移相器的接入对线路纵联保护的影响分析

Analysis of the Influence of Ice-melting Phase Shifting Transformer Access on Line Longitudinal Protection

针对凝冻天气线路覆冰的问题,利用对称双芯移相变压器(phase shifting transformer,PST)的移相特性实现线路在线融冰。首先按照PST原理和运行要求,设计了PST的电路结构和控制保护系统。然后,根据PST的结构、PST对各序网故障分量的移相特性、叠加定理,结合线路纵联保护中零序电流差动保护、稳态分相电流差动保护、分相突变量电流差动保护的逻辑算法,分析了PST接入对线路纵联保护动作特性的影响机理,并从3个方面提出改进策略。最后,利用仿真验证了理论推导的正确性和改进方案的有效性。

Aiming at solving the problem of line icing in freezing weather,the phase shifting characteristics of the symmetrical double-core phase shifting transformer(PST)is used to realize line on-line ice melting.First,according to the principle and operation requirements of PST,the circuit structure and control protection system of PST are designed.Then,according to the structure of PST,phase-shifting characteristics of PST to the fault components of each sequence network and superposition theorem,combined with the logic algorithms of zero sequence current differential protection,steady-state split-phase current differential protection and split-phase sudden variable current differential protection in the line longitudinal protection,the paper analyzes the mechanism of PST access to the action characteristics of the line longitudinal protection,and puts forward the improvement strategies from three aspects.Finally,simulation is used to verify the correctness of the theoretical derivation and the effectiveness of the improved schemes.