Experiences in 735 kV Series Compensation Protection and Control System Upgrading Project

To prolong the overall life of 735 kV SC (series compensation) system, the electronic devices on the platform, optical signal columns and the SC protection and control cabinets in the control room need to be replaced. The upgrading proposal solution of SC protection and control system was designed and some key functions were tested and verified. The forced triggered test of plasma injectors using new gap trigger unit was performed in the laboratory. A test circuit is designed to test the time delay from the real energy or current of MOV exceeding the setting to the high voltage impulse released by the triggering circuit. The environmental tests, EMC tests, and vibration tests were carried out on the SC protection and control system. Specifically, for the outdoor electronics and equipment, the −50 °C low temperature withstand test was performed. For the optical signal column, the design test, type test, and temperature cycle test were performed. And the full-sized optical signal column not the samples was selected to perform the temperature cycle test from −50 °C to +50°C. After completing all the cabinets and equipment installation, the commission test was performed, especially the forced triggered tests of plasma injector were verified again using real system. Finally, the energization tests were carried out, and there were no any alarm signals during the energization tests. The anti-EMI performance of the electronics on the platform was verified.