A novel dynamic phasor based interface models for hybrid simulations of EMT and transient stability models

In order to accurately and efficiently analyze the interactions between HVDC and the AC grids, the hybrid simulations of EMT and transient stability models are widely used. However, the dynamics of the inverter are sensitive to the waveforms of AC system. Waveform distortion and time delay caused by interfacing will significantly increase the interface errors, thus affecting the overall accuracy of the simulations. To resolve the above-mentioned problems, a novel dynamic phasor based interface model (DPIM) is proposed in this paper to improve the accuracy of interface variables when the fault locates near the inverter. As a result, the whole system is partitioned into three parts: the transient stability (TS) subsystem, EMT subsystem, and the connection between them is constructed by DPIM. Unlike the traditional method, it can avoid the delay errors caused by interfacing, thus promotes the accuracy improvement of interfaces in the TS subsystem. Also, the calculations of the interface parameters are greatly reduced. The effectiveness of the proposed method in terms of accuracy and efficiency is validated by simulating a practical HVDC Project.