基于智能配变终端的变压器低压保护改进策略

Operation analysis and improvement strategies of low voltage protection for transformer based on intelligent transformer terminal unit

目前配电网变压器多采取传统的保护配置模式,若长期处于过负荷、三相不平衡运行状态,极易造成损坏。因此,提出一种基于智能配变终端的配电变压器低压保护改进策略,通过分析配电变压器低压保护运行情况和配置现状,指出现有配电变压器保护配置模式存在着过载保护动作时间离散性大、三相不平衡尚无有效保护手段等问题。基于此,将低压线路电流划分为4个保护区间,采用循环限电和延时复电方式实现精确的配变低压过载保护;与此同时,通过实时计算获得配变三相不平衡度,对低压三相负荷实行动态管理和自动无功补偿,降低三相电流的不平衡度。该方法有效解决了配电变压器低压保护存在的问题,保障了低压用户的供电可靠性和电能质量。

The distribution transformer which is in long-term overload or three phase unbalance operation state will be easily damaged when the traditional protection and configuration mode is adopted. Therefore, an improvement strategy is proposed on basis of the intelligent transformer terminal unit. By analyzing the operation and configuration of low voltage protection of distribution transformer, the problems of the overload and the three-phase unbalance protection of distribution transformer are pointed out. The line current is divided into four protection intervals. The rolling power cuts and the delay power supply are used to optimize the overload protection of distribution transformer. Furthermore, the real-time acquisition and calculation are employed in the three-phase unbalance factor to realize dynamic management and auto-reactive compensation, and balance the three phase load. The proposed method can effectively solve problems existing in the low voltage protection of distribution transformer, increase power supply reliability and ensure power quality of low voltage user.