Risk Assessment on 22kV Load Transfer Cable Sheath Under N-2 of 161kV Main Substations for Wen-Hu Line

• Main Authors: Hisn-Fu Lin, 林信甫
• Other Authors: Shi-Lin Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/60538785156576515276

碩士 === 中原大學 === 電機工程研究所 === 104 === Taipei Rapid Transit Corporation (TRTC) plans to increase the power supply reliability of 161kV Bulk Supply Substation (BSS) of Wenhu Line by upgrading original N-1 to N-2 design criterion. The former refers to the power system design which allows the outage of one 161kV BSS and the latter allows the simultaneous outage of two BSS’s in the same Wenshan or Neihu Line. That is, under the outage of two BSS’s in the Wenshan Line, the closest BSS of Neihu Line must be able to supply power to Wenshan, and vice versa for the outage of Neihu and the power supply from Wenshan. Since the Neihu Line was planned as an extension to the Wenshan Line, TRTC has evaluated for the ampacity of the 22kV load transfer cables, but not for shielding layer pressure and ampacity of the cable sheath during power transferring. The thesis focuses on evaluating shielding layer pressure and ampacity of 22kV load transfer cable sheath Under N-2 of 161kV Main Substations for Wen-Hu Line. By using Alternative Transients Program, we simulate power outage of two 161kV BSSs in Wenshan Line, and power supply from the HUCHYEI BSS. We further discuss about the shielding layer pressure of load transfer cables of two Lines during load transfer period, especially the existing single-layer shielding grounded and the other end open. Based on EN50122 standard and standard of the 161kV underground cable manhole of CCPU (Cable Cover Protection Unit) of Taipower, the shielding layer pressure does not meet specifications. As a result, we recommend 22kV load transfer cables to ground. Comparing and analyzing the simulating two grounds current and the safe ampacity of shielding layer, according the calculation, suggest that the maximum headway is 85s during load transfer period .