同相供电设备有功功率差动保护

由于隔离变压器的副边额定电流很大,且难以选择电流互感器,因此隔离变压器很难设置灵敏的电流差动保护。为了给隔离变压器、隔离变压器与潮流控制器之间的连接电缆提供灵敏的保护,并给潮流控制器提供灵敏的远后备保护,文中从理论上分析了同相供电设备的基波输入有功功率与输出有功功率相等这一特性,并基于这一特性提出了同相供电设备有功功率差动保护方案,进而对有功功率差动保护在隔离变压器空载投入、潮流控制器启动、正常运行、外部故障、内部故障等各种工况下的动作行为进行了分析。文中还对同相供电设备有功功率差动保护的整定原则作了讨论,并给出了整定实例。实验室测试和工程现场运行测试结果表明了有功功率差动保护的正确性。

Active Power Differential Protection for Cophase Supply Equipments

Because of huge current in low voltage side of an isolated transformer,it is difficult to select a matched current transformer and apply sensitive current differential protection to the isolated transformer.In order to provide more sensitive protection to the isolated transformer,power flow controller(PFC) and the electric cables between them,the relation of fundamental input active power to output active power of cophase supply equipments is analyzed theoretically.Based on balance of active power,an active power differential protection(APDP) scheme is presented.Moreover,the operation behaviors of APDP are analyzed under many conditions,such as the isolated transformer energizing,PFC initiation,normal operation,external fault,internal fault and so on.The setting principle of APDP for cophase supply equipments is discussed,and a real instance is also given.The test results in lab and project field show the validity of APDP.