普侨直流普洱换流站内接地网替代接地极双极运行方案

首先分析了普侨直流普洱换流站接地网替代接地极双极运行的必要性,接着对接地网替代接地极运行可行性开展一系列研究,主要包括:鉴于接地极和接地网设计原则差异,对接地网热稳定性、接触电压和跨步电压等开展校核;为最大限度减少不平衡电流进入站内接地网,提出了优化双极解/闭锁同步逻辑、双极电流跟随同步逻辑和双极联跳逻辑,同时为最大限度满足系统、设备及人身安全要求,提出优化整流侧76SG、整流侧87GPS及逆变侧60EL等保护功能。现场运行表明:通过对直流站控功能、极控功能及保护功能进行优化后,普侨直流完全能适应普洱换流站接地网替代接地极双极运行方式,双极解/闭锁、双极联跳时差较小,一致性较好;各种运行工况下,站内一次设备安全运行、人身安全及二次设备安全运行等均满足规程要求。

Analysis on Bipolar Operation of Puqiao UHVDC with Station Ground Mat Replacing Electrode in Puer Rectifying Station

First the necessity of bipolar operation with station ground mat in Puer rectifying station of Puqiao ultra high voltage direct current(UHVDC)replacing electrode is analyzed, and then the bipolar operation feasibility is studied in depth, including verification of thermal stability of station ground mat, verification of contact voltage and stepping voltage are checked. Some control and protection optimizations are proposed to avoid big current injecting into station ground mat and ensure the safety of system, people and equipment, including synchronous unlock and lock logic, bipolar current tracking, bipolar synchronous tripping logic, 76SG and 87GPS protection in rectifying station and 60EL in inverting station. On-site operation shows that optimizations of direct current(DC)station control, pole control and DC protection can satisfy bipolar operation with station ground mat, and the safety requirements of primary equipment, secondary equipment and people all can meet the proposed standards.