Performance Investigation of a Monopolar HVDC Transmission System Feeding a Weak AC Network

This paper investigates the performance of line commutated converter (LCC) based monopolar HVDC transmission system feeding a weak AC network with hybrid reactive power compensators (RPC’s) at the inverter AC side. The hybrid compensator is an equal mix of any two of the following compensators: synchronous compensator (SC); static var compensator (SVC); static synchronous compensator (STATCOM). The HVDC transmission system model is implemented in the Matlab with the firefly algorithm based optimal proportional integral (PI) controller for rectifier and inverter control. The transient performances of hybrid RPC’s (SC+SVC, SVC+STATCOM and SC+STATCOM) are judged under various fault conditions and the outcomes are compared with the performance of the SC, SVC and STATCOM to highlight the supremacy of the hybrid compensators. The simulation results validate that the equal mix of SC and STATCOM has a steady and fastest response. The results also demonstrate the superiority of the firefly algorithm based optimal PI controller over the conventional PI controller. The harmonic analysis is also carried out under steady state operation to assure the quality of power supply on the inverter AC side.