Modified average‐value model for high‐performance fault transient simulation of AC‐DC hybrid power networks

Abstract

Abstract Due to the complicated transients and the possibility of transition from a minor fault in AC subsystems to a severe blocking event of a high‐voltage direct–current (HVDC) transmission line, the study of AC‐DC hybrid power systems requires both efficient and accurate electromagnetic transient (EMT) simulation. However, the computational efficiency of such simulations is restrained by the switching events when detailed models of line‐commutated converters (LCCs) are used. Recently the average‐value modelling technique has been developed for accelerating the simulation while still accurately capturing the transient characteristics of line‐commutated AC–DC converters. This study presents the application of the average‐value model in the modelling of the LCC‐HVDC system and gives a further discussion about the deficiency of the model. A modified interface and the corresponding soft‐switching technique are proposed for enhancing the simulation performance of the LCC‐HVDC model in the transition between normal and faulty operation. The model is tested on a series of LCC‐based systems including a hybrid power system with four LCC‐HVDC lines to verify its efficiency and accuracy. The results indicate that the developed model can accurately predict the transients of the system both in symmetrical and asymmetrical operation while being computationally efficient.