GB/T 20996.2-2020 Active

This part of GB/T 20996 is a guidance document on the transient performance and fault protection requirements of high-voltage DC systems; it discusses the transient performance of faults and operations in two-terminal high-voltage DC systems composed of 12-pulse (dynamic) converter units connected in a three-phase bridge (double-line) configuration, and does not involve multi-terminal high-voltage DC transmission systems. However, it discusses parallel converters and parallel lines included in two-terminal systems; it assumes that the converters use thyristor valves as bridge arms and insulation coordination with gapless metal oxide surge arresters, and power can be bidirectionally transmitted. This part does not consider diode valves.
This part only involves grid-connected phase converters, including converters with capacitor phase-shifting circuit structures. General requirements for grid-connected phase converters are given in IEC 60146-1-1, IEC 60146-1-2, and IEC 60146-1-31. This part does not consider voltage source converters.
GB/T 20996 consists of three parts: steady-state, fault and operation, and dynamic. During the development and drafting process, efforts have been made to avoid duplication of content among the three parts. Therefore, when users prepare specifications for two-terminal high-voltage DC systems, they should refer to all three parts.
For various components of the system, attention should be paid to the differences between system performance specifications and equipment design specifications. This part does not stipulate equipment technical conditions and test requirements, but focuses on those technical requirements that affect system performance. This part also does not include detailed earthquake performance requirements. In addition, there may be many differences among different high-voltage DC systems, and this part does not discuss these in detail. Therefore, this part should not be directly used as a technical specifi