PROTECTION OF 220 kV 50 MVAr SHUNT REACTOR AT TRANSPOWER'S WAIRAU RD SUBSTATION

摘要

The North Auckland and Northland (NAaN) upgrade project has been undertaken by Transpower to reinforce their 220 kV network from Auckland to North Auckland with the installation of new cable circuits from Pakuranga to Albany through various substations. A 220 kV, 50 MVAr shunt reactor directly connected into a 2500 A, 9 km cable circuit was installed at Wairau Road Substation to counteract shunt capacitance and associated voltage rise associated with the cable circuits. This paper describes the unique challenges associated with applying traditional transformer biased differential schemes with circuit breaker fail to directly connected shunt reactors. Attention is paid to the effects of Point on Wave circuit breaker control on inrush current characteristics, resonance effects following line de-energisation and the ability of biased differential schemes to provide security during various switching and contingency events. Disturbance records following commissioning are analysed in order to assess the impact on the selected settings and confirm security of the scheme.