Assessment of stability effects of HVDC link by an improved energy function method

This paper proposes new techniques for the fast transient stability analysis of power systems embedded with HVDC (high voltage DC link) based on a corrected transient energy function approach. The method is based on an innovative iteration approach used to evaluate the AC terminal voltages of HVDC links at each integration step and is developed for enhancing the efficiency of stability trajectory calculations. In addition, the corrected energy function approach with corrected transient energy and corrected potential energy boundary surface is used in the AC/DC system for the estimation of transient energy margin. The approach provides more accurate results in transient stability assessment than conventional hybrid methods. Simulation results on a 36-bus, 8-generator test AC/DC power system are presented to show that the approach offers a promising tool to estimate transient stability limit conditions for AC/DC systems.