Control and Voltage Stability of A Medium Voltage DC Micro-Grid Involving Pulsed Load

摘要

Recent increase in the demand of medium voltage DC (MVDC) systems is due to the high penetration of distributed generators, pulsed loads and energy storage systems (ESS). This paper develops control techniques to improve the voltage stability of an islanded multi-terminal MVDC ship-board. The ship-board accommodate three synchronous generators interfaced via bi directional AC-DC converters as well as pulsed load. The control system has two objectives; 1) limiting the current flow in the MVDC ship-board cables, and 2) Support voltage profile stability even under pulsed load condition. This was achieved through two stages; 1) operating the ship-board converters in master-slave mode in nominal operation and 2) utilizing ultracapacitor (UC) to support the voltage stability in pulsed load conditions. The dynamics of the control loops were investigated in the PSCAD/EMTDC environment. The results proved the effectiveness of the control technique and the employment of the UC to support voltage stability.