Exploring the Protective Coordination Problems of Overcurrent Relays and Distance Relays in Transmission Networks

• Main Authors: Jarm-Long Chung, 鍾彰榮
• Other Authors: 周至如
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/xjce89

博士 === 國立臺北科技大學 === 電機工程系所 === 98 === The protective coordination provided by protective relays in the transmission systems is important for power safety and quality. Overcurrent relays are mainly used in protecting the subtransmission and distribution systems. In practice, the coordination curve intersection of a downstream and upstream relay pair will cause unexpected augmentation of the blackout area as a fault occurs in the downstream relay side. In addition, in a single ring or a complex low voltage power transmission network with many buses cascaded, expensive power equipments would be damaged due to long operating times of relays when a fault occurs in a transmission line. EHV and HV transmission networks usually employ distance relays as protective devices. In practice, miscalculation of the apparent impedance and the short length of a transmission line are two major problems encountered in the distance relay protective coordination. In this thesis, these problems are investigated and the preceding protective coordination the novel approache mothod are proposed to effectively solve the improper coordination.