A Study of High-Impedance Differential Relay on Double Bus Protection

• Main Authors: Lung-tien Tsai, 蔡隆田
• Other Authors: Jyh-Cherng Gu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/nvhs39

碩士 === 國立臺灣科技大學 === 電機工程系 === 94 === Bus-bar plays a very critical and important role in electrical power system, because it links all or part of generation, transmission and distribution systems together. In other words, short circuit fault in bus-bar may incur serious fault current which is supplied from diverse sources. Fast response and correctness are the major requirements for bus-bar protection to limit the equipment damage, secure system stability and provide reliable power supply. However, the dc-offset component accomplished with fault current may cause saturation effect in current transformer (CT). CT saturation in bus-bar system may lead to misoperation of overcurrent differential relay. Traditionally, a time delay solution in overcurrent differential relay setting is proposed to prevent such mistake. Hence, fast response of this traditional protection scheme is impossible. To overcome this difficulty a high-impedance differential relay scheme is presented for double-bus protection. The suitability and performance of high impedance differential relay protection scheme for double-bus protection will be further explored. In this thesis, one uses EMTP/ATP setup a mathematic model for CT and an example double bus system. Then, many fault conditions including CT saturation effect are intensively simulated and discussed. Finally, an effective solution is proposed and verified to improve the security and sensitivity of double bus protection.