高压晶闸管换流阀电控型和光控型晶闸管反向恢复期的不同保护策略

Different Protection Tactics for Electric Triggered Thyristor and Light Triggered Thyristor Valve About Reverse Recovery Period

随着我国高压直流输电(HVDC)的发展,不管是电控型(ETT)还是光控型(LTT)晶闸管换流阀,在运行中其反向恢复期(reverse recovery period)保护功能均出现了一些缺陷和问题,导致换流阀强迫停运。为此,作者在对这两种不同技术换流阀反向恢复期的机理和不同的保护策略进行分析研究的基础上,针对在工程运行中该保护出现误判、误动、延时形成死区等缺陷的原因进行了分析,得出主要原因为ETT阀未能采用直接的正向电压变换率(du/dt)探测,而LTT阀则因该保护无双重化配置和监测功能。针对此,进而提出ETT阀改进为直接du/dt保护的策略;在LTT阀的RPU保护单元增加双重化配置和监测功能的优化方案,为这一关键保护更加精准有效提出了一种自主国产化的新思路。

With the development of HVDC transmission, ETT and LTT thyristor valves have some problems and defects at the protection of the thyristor reverse recovery period in the operation expreince of HVDC project, even results in the forced outage of converter. We analyzed and researched the protection tactics of the thyristor valve at the reverse recovery period, and analyzed the defect of dead zone caused by misjudge, malfunction or delay in the protection during operation. For ETT valves, the main reason is that direct du/dt detection is not used. For LTT valves, they are non dual-configuration without any feedback detection. Therefore, du/dt protection is adopted directly in ETT valves, and a double design and feedback detection are adopted for RPU of LTT valves as optimization. Furthermore, we put forward a new idea for do- mestic production with a more accurate and effective way for the key protection.