中文摘要：

为解决传统变电站后备保护在配置和原理方面存在的问题，提出了适用于智能变电站的基于电流差动原理的站域后备保护新方案。该方案以变电站及所有出线为保护对象，定义了四类不同特性的差动区，根据其处于制动状态或者差动状态来实现故障定位，并根据主保护和断路器的动作信号确定后备保护的跳闸策略。详细阐述了站域差动后备保护的工作原理、故障元件定位流程以及主、后备保护之间的协调控制方法。采用该方案的智能变电站，保留传统的面向间隔的主保护，集中配置站域后备保护，简化了后备保护的配置和整定。利用PSCAD软件构建了典型变电站仿真模型，对正常运行、保护区内外故障等不同运行状态进行了全面仿真，验证了所提方案的正确性。

英文摘要：

To solve the problems related to configuration and principle of backup protection in conventional substations, this paper proposes a new scheme of substation-area differential backup protection （SDBP） oriented to intelligent substations. The new scheme takes the whole substation and all connected transmission lines as the object to be protected. Through defining four types of differential zone, the SDBP can accurately locate the faulted component according to whether the differential zone lies in restraining state or operating state. The tripping strategy of SDBP is determined by action signals from both main protection and circuit breakers. This paper describes in detail the scheme＇s operating principle, fault location process, and coordinating method with main protection. The intelligent substations adopting proposed scheme will be configured by bay oriented main protections and only one set of SDBP, which simplifies the configuration and setting of backup protection. The validity of SDBP scheme has been verified by PSCAD simulation model under the condition of normaI state and fault state with different types and locations.