锦苏±800 kV特高压直流输电苏州站投运过程中，发生失谐保护频繁发信事件，通过对失谐保护原理、保护逻辑、动作过程等深度分析，指出6次谐波分量的影响是主要原因。提出在建设特高压直流输电换流站时，需要吸取失谐保护频繁发信事件的教训，实时检测交流系统谐波电压状况，紧密监视直流偏磁对电网的影响，排查隐患消除缺陷。建议针对失谐保护频繁发信案例，深入研究换流变充电励磁涌流对交流系统谐波的影响。

JinSu±800kV UHV DC transmission process Su Zhou station was put into operation, detuning protection frequently transmitting incidents, through to the detuning protection principle, protection logic, action process etc depth analysis, points out the influence of six times harmonic is the main reason. Put forward in the building of the UHV DC converter station, need to learn detuning protection frequently transmitting events, real-time detection condition of the AC system harmonic voltage, closely monitor the DC bias influence on grid, trying to identify hidden trouble to eliminate defects. Suggestions for frequent case detuning protection, in-depth study in converter transformers charging the influence of harmonic excitation inrush current of AC system.