Small Signal Stability based Controller Tuning for Enhanced LVRT Performance of VSC-HVDC Transmission System

Abstract

This paper proposes an optimization based tuning technique for a two-terminal Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) transmission system with a Modified Reactive Power Controller (MRPC). Latency in controller switching and gain modulation is avoided by employing MRPC controller. Reactive power reference modulation strategy is employed to provide optimal Low Voltage Ride Through (LVRT) support. The state space model is derived and initialized from steady state operating conditions prior to the onset of dynamic behavior of the system. The critical modes are identified. From the normalized participation factor matrix, the LVRT sensitive modes and the DC voltage sensitive modes are identified. The objective function of the optimization technique is to enhance the stability and damping, prioritizing LVRT support and reduction of DC bus voltage oscillations. Comprehensive Simulation studies are done using PSCAD/EMTDC. On occurrence of fault or low voltage pocket, the improved performance of the proposed tuning technique over traditional tuning for various operating conditions is demonstrated.