新东特高压直流孤岛运行闭锁策略

Blocking Strategy for Xinsong-Dongfang UHVDC Project in Island Operation Mode

新东特高压直流投产初期,送端机组投产滞后导致孤岛短路容量不足,孤岛运行存在过电压、低次谐波谐振等风险。为保证被动跳入孤岛设备安全,提出新东特高压直流跳入孤岛闭锁策略,即在直流站系统中增加跳入孤岛主动闭锁直流功能,并采用交流联络线低功率防误判据来有效防止联网方式下该策略误动作。采用先切除全部滤波器,再延时闭锁直流,最后稳控系统全切孤岛运行机组的策略,能有效降低孤岛直流闭锁的过电压,保证相关设备安全。现场实施表明:直流跳入孤岛后能够在300ms内切除全部交流滤波器,交流滤波器全切后延时约30ms直流启动闭锁,双极闭锁后稳控系统延时切除孤岛全部机组,闭锁逻辑和稳控策略均正确,孤岛内过电压和频率均满足要求。

During the initial operation of Xinsong-Dongfang ultra-high voltage direct current（UHVDC）project,the delayed operation of sending generators results in insufficient capacity of island short-circuit and risks such as overvoltage and low-order resonance.In order to ensure the safety of devices when the UHVDC project passively jumps into island operation,this paper proposes a blocking strategy for Xinsong-Dongfang UHVDC project jumped into island operation,i.e.,add the automatic blocking function for island operation in the DC station control system,and adopt a low-power anti-false criterion of AC tie-line to effectively prevent the strategy from malfunctioning in the grid-connected mode.A strategy as follows can effectively reduce the overvoltage of the island UHVDC blocking and ensure the safety of related equipment：firstly,cut off all the filters;secondly,delay the UHVDC blocking;thirdly,the stability control system cut all generators in island operation mode.Field application shows that all AC filters can be cut within 300 ms after the UHVDC project jumps into island operation,and the UHVDC blocking is initiated after a delay time of 30 ms,then the stability control system delays after bipolar blocking,while all the island generators are accurately cut.The blocking logic and the stability control strategy are correct,and the overvoltage and frequency meet the requirement of the specification.