Extra-sensitive impedance differential protection immune to CT saturation
Extra-sensitive impedance differential protection immune to CT saturation
复制标题
超灵敏阻抗差动保护不受 CT 饱和影响
DOI：
10.1049/iet-gtd.2019.1935
复制
发表时间：
2020
影响因子：
2.5
通讯作者：
Xiong Zhiwu
中科院分区：
文献类型：
--
作者：
Tong Ning;Lin Xiangning;Zhang Rui;Zhuo Yixin;Jin Neng;Li Zhengtian;Xiong Zhiwu
对于配置了通信通道的特高压输电线路，电流差动保护面临着灵敏度和安全性之间的两难选择。一方面，如果安全得到保证，阻力覆盖率将不会足够高。虽然顺序电流型差动元件的灵敏度较高，但在非全相运行条件下，可能会导致较长的时间延迟和灵敏度恶化。另一方面，如果以牺牲安全为代价来保证高灵敏度，则在电流互感器(CT)饱和的情况下，主保护元件将被阻断。为解决这一问题，提出了一种新型的阻抗差动保护。在等待自动重合闸的缺相情况下，该IDP能帮助加快健康相的故障清除速度，比使用零序电流差动保护更快、更灵敏。对于CT饱和严重的外部故障，所提出的IDP可以在CT恢复之前接管故障识别能力，在此期间电流差动保护被阻断。仿真结果表明，在上述两种情况下，所提出的IDP与电流差动保护配合良好。还使用实地数据评估了拟议境内流离失所者的业绩。
For extra‐high voltage transmission lines configured with a communication channel, the current differential protection is facing a dilemma between sensitivity and security. On the one hand, the resistive coverage will not be sufficiently high if security is guaranteed. Although the sequence‐current‐based differential elements are more sensitive, it may cause a longer time delay and deteriorate sensitivity under the open‐phase operating condition. On the other hand, if high sensitivity is guaranteed at the cost of security, the main protection element will be blocked in the current transformer (CT) saturation scenario. To solve this problem, a novel type of impedance differential protection (IDP) is proposed. Under the open‐phase condition awaiting an automatic reclosing, the proposed IDP can assist in accelerating the speed of fault‐clearance for healthy phases, which is faster and more sensitive than using the zero‐sequence current differential protection. For an external fault with heavy CT saturation, the proposed IDP can take over the fault identification capability before the recovery of CT, in which duration the current differential protection is blocked. Simulation results indicate that the proposed IDP coordinate perfectly with the current differential protection in the above two scenarios. The performance of the proposed IDP is also assessed using field data.