基于RTDS实时闭环仿真系统的交直流过电压建模研究

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

电力系统过电压是发展高压、超高压和特高压电网所必须研究的课题。通过对RTDS避雷器等过电压研究关键仿真模型的研究,认为当前RTDS基本能够适用于针对直流双极闭锁、直流甩负荷等故障引起的交流系统过电压水平和过电压抑制策略的研究与分析。介绍了换流变磁饱和特性和避雷器非线性特性的RTDS仿真建模,换流变的磁饱和特性和避雷器的非线性特性的准确模拟对过电压研究的准确性和分析的可参考性具有重要的意义。RTDS直流阀组模型没有设置磁饱和特性仿真,因此需要在换流母线上添加非线性仿真元件,数学模拟换流变的磁饱和特性。由于实时快速仿真的需要,RTDS避雷器模型通过一种特殊的分段仿真方法描述避雷器的非线性特征,对模型的参数要求合理配置以增强仿真准确度。

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.