Simulated Researches On The Characters Of UHVDC Overvoltage Based On Transient-Calculation Model

The feature of the distribution of energy and load in China decides that UHVAC or UHVDC transmission technology should be used to long distance and large capacity power transmission.±1000kV UHVDC transmission has significant advantages in the low loss, ultra-long-distance and large-capacity power transmission capacity. State Grid Corporation has planned to use±1000kV UHVDC transmission in individual HVDC transmission project. Therefore, the study of the overvoltage of±1000kV UHVDC transmission system is of great significance.In this paper, the electromagnetic transient calculation model of±1000kV UHVDC system is established by using PSCAD, an electromagnetic transient analysis software which is internationally accepted. In this work, the important parts, such as the convertr, transformer, and inductance filter are modeled firstly. Based on these modles, a whole±1000kV UHVDC transmission system is set up considering the converting control strategy. And then various failures and operation are simulated both in the DC side and AC side. These failures include the fault in the converter, the DC line to the ground, the AC line, et al; these operations include the poles conversion of the DC transmition, the operation on the inductance filter, cutting off the load and other typical opation. The overvoltages under these failures and operation are calculated and analysed. Finally some useful laws are concluded. These laws can procvide technical basis for the study of insulation coordination of±1000kV UHVDC transmission system, and provide some technical support to the strategies toward the overvoltage’s impact.