Load Margin for Short-term Voltage Stability of an Interconnected AC/MTDC System

The so-called short-term voltage stability is typical of nonlinear problems arising in dynamic performance of electric power systems. This paper reports a simulation result on load margin for short-term voltage stability of the IEEE 9-bus system connected to a multi-terminal DC system based on voltage-source converter (VSC). The simulation shows that the introduction of AC voltage control in VSC increases the load margin under a step change in load on the AC system, thereby showing a clear benefit of the AC voltage control for enhancing the short-term voltage stability without harnessing the AC system.