Preliminary Discussion on Over-voltage Studies of RTDS-Based Real-time Closed-loop AC/DC Simulation System

Power system over-voltage(OV) studies are necessary for developing high-voltage,extra-high voltage and ultrahigh voltage grids.Though the analysis of some RTDS models,which are very pivotal for OV studies,a conclusion can be given that RTDS currently can be used to analysis OV level and its control strategies of AC system when disturbances happen,such as bipolar DC is blocked and rejects its load.The RTDS models of arrester and magnetizing branch of converter transformer,whose proper simulation are very crucial for the correctness and credibility of OV studies,are introduced.There is no magnetizing branch modeled in the HVDC valve group model of RTDS,so some new models should be added and connected to the converter bus to simulate the magnetizing saturation characteristics of converter transformer.For real-time and fast simulation,RTDS represents the Non-linear characteristics of arrestor with a special piece-wise function,and the parameters of the model should be set properly for a correct simulation.