交流系统变压器直流偏磁防护决策研究

Research on Decision-making of Transformer DC Magnetic Bias Protection in AC System

现有变压器偏磁的直流防护中,缺乏用治理直流偏磁风险变电站的决策型方案。为解决该问题,通过分析直流偏磁产生的根本原因,指出变电站的不同连接分布是造成直流偏磁现象的直接因素。从实验角度出发,以酒泉—湖南±800 kV直流送端系统为研究对象,建立送端电网等效直流模型,通过研究变电站与接地极分布、变电站站间连接分布以及并联运行变压器台数和加装抑直设备4种因素影响下的直流电流分布规律,提出了直流抑制设备在交流电网中的部署策略,经过在送端电网的应用,变压器偏磁水平得到了良好控制,为今后解决同类问题提供了指导性建议。

In the DC protection of existing transformer bias magnetic field,there is lack of a decision-making scheme for controlling the risk of DC bias magnetic substation.In order to solve this problem,by analyzing the root cause of DC bias,it is pointed out that the different connection distributions of substations are the direct cause of DC bias.From the experimental point of view,a direct-current system of Jiuquan-Hunan±800 kV DC transmission system is used as the research object,and the equivalent DC model of the transmission end power grid is established.The substation and the distribution of grounding electrodes,the connection distribution between substation stations,the number of transformers connected in parallel,and the installation of suppression are studied.Based on the direct current distribution law under the influence of four factors of the direct equipment,the deployment strategy of the DC suppression equipment in the AC power grid is proposed.After the transmission end network configuration,the transformer magnetic bias level is well controlled,providing suggestions for solving similar problems.