Reactive Power Control in ± 800 kV HVDC Converter Station Biswanath Chariali, POWERGRID

In a high voltage direct current (HVDC) transmission converter station, the purpose of the Reactive Power Control (RPC) is to facilitate the switching of alternating current (ac) filters to meet the reactive power demand with the ongoing dc power flow. In addition to it, the RPC will also ensure that the required ac filters are connected to prevent harmonics from entering into the AC system. In a comparatively smaller grid like North Eastern Region (NER) of India, with RPC in automatic mode, the switching in of ac filter sub banks of HVDC system due to sudden rise of transmitted dc power through the HVDC link during oscillations in the connected ac grid causes significant rise in ac voltage was a challenge and this challenge has been solved practically. By using the manual scheme of RPC without compromising the quality of power and by connecting bus reactors the problem of sudden rise of ac voltage during oscillations have been resolved.