Performance of Hybrid Reactive Power Compensators in a Multi-terminal Hvdc Transmission System Feeding Weak Ac Networks during Transient Fault Conditions

In this paper performance analysis of various hybrid reactive power compensators (RPC’s) at the inverter AC sides of a line commutated converter (LCC) based multi-terminal HVDC (MTDC) transmission system, feeding weak AC networks, is carried out to thoroughly gather the mechanisms of interactions between an HVDC system and weak AC systems. The hybrid compensator is realized by equally mixing the fixed capacitor (FC) with any one of the following compensators: synchronous compensator (SC); static var compensator (SVC); static synchronous compensator (STATCOM). The HVDC transmission system model is simulated using Matlab with firefly algorithm based optimal proportional integral (PI) controller for rectifiers and inverters control. The performances of hybrid RPC’s (FC+SC, FC+SVC and FC+STATCOM) are investigated during various transient fault conditions and the results are compared with the performance of the SC, SVC and STATCOM to focus the supremacy of the hybrid compensators. The simulation results authorize that the equal combination of FC and STATCOM has a steady and fastest response. The outcomes also demonstrate the superiority of the firefly algorithm based optimal PI controller over the conventional PI controller. The harmonic existing in the inverter AC side is also observed under steady state operation to ascertain the quality of power supply.