1. 1 © ABB Automation Technologies AB, 2005 2005-03-04 PTSX/TP/A Janez Zakonjsek PS03_Q11_SE Janez Zakonjsek

2. 2 © ABB Automation Technologies AB, 2005 2005-03-04 PTSX/TP/A Janez Zakonjsek Question 11 Question #11: a) What are the current experiences with auto-reclosing on series compensated transmission lines?; and, b) What are the technical challenges and proposed solutions? Consider duty cycles for the capacitor bank elements

3. 3 © ABB Automation Technologies AB, 2005 2005-03-04 PTSX/TP/A Janez Zakonjsek Duty cycle – external fault & unsuccessful autoreclosing Time (ms)Power System EventThyristor Controlled Series Capacitor Action 0.0Fault application- 0.0 to 100Fault remainsThe TCSC line current supervision detects high line current and bypasses the TCSC via the thyristor valve. 100.0Line circuit breakers clear the fault 100.0 to 600.0Power flows through the lineThe TCSC is reinserted. 600.0Line circuit breakers reclose into the fault - 600.0 to 700.0Fault remainsThe TCSC line current supervision detects high line current and bypasses the TCSC via the thyristor valve. 700.0Line circuit breakers clear the fault and lock out. 700.0 to -The TCSC is reinserted.

4. 4 © ABB Automation Technologies AB, 2005 2005-03-04 PTSX/TP/A Janez Zakonjsek Duty cycle – internal fault & successful autoreclosing Time (ms)Power System Event Thyristor Controlled Series Capacitor Action 0.0Fault application- 0.0 to 100Fault remainsThe TCSC line current supervision detects high line current and bypasses the TCSC via the tyristor valve and the bypass switch. 100.0Line circuit breakers clear the fault Series capacitor remains bypassed 100.0 to 600.0 The line is disconnected. The fault disappears The series capacitor remains bypassed. 600.0Line circuit breakers reclose - 600.0 to -The series capacitor is automatically reinserted.

5. 5 © ABB Automation Technologies AB, 2005 2005-03-04 PTSX/TP/A Janez Zakonjsek Challenges – Multi-pole tripping and sequential reclosing