基于PSCAD的特高压自耦变直流偏磁及无功损耗特性分析

Analysis on DC Magnetic Bias and Reactive Loss Characteristics of UHV Autotransformer Based on PSCAD

由于特高压自耦变易受直流偏磁电流的影响,随着中国1000kV特高压电网逐步投入运行,研究1000kV特高压自耦变直流偏磁影响下的无功损耗特性具有重要意义。文中针对我国自主研发的1000kV特高压自耦变,首先依据自耦变直流偏磁下励磁电流与磁链的非线性曲线,建立偏磁电流与无功损耗间的数学模型;然后利用厂家所提供的1000kV特高压U-I曲线与铭牌参数,在PSCAD平台中建立仿真模型,进行特高压自耦变直流偏磁仿真研究,仿真结果表明,特高压自耦变单相无功损耗与单相直流偏磁电流近似呈线性关系,与理论分析的结论一致;最后根据仿真计算结果获得了自耦变单相无功损耗与单相直流偏磁电流间的比例关系,其中,空载时其比例系数为0.77;额定负载时其比例系数为0.76。

Since the UHV autotransformer is susceptible to the DC magnetic bias, it is necessary to research the reactive loss characteristics of the autotransformer under the influence of DC magnetic bias. Focusing on the 1 000 kV UHV autotransformer developed by Chinese, this study establishes a mathematical model to describe the relatio ship between DC magnetic bias and reactive loss according to the nonlinear curve of excitation current and flux linkage of the autotransformer with DC magnetic bias. Then, a simulation model is built on PSCAD platform using the ta of 1 000 kV UHV U-I curve and the nameplate parameters provided by the manufacturer, in order to analyze the DC magnetic bias phenomenon of the autotransformer. Simulation results show that the single-phase reactive loss of the autotransformer has an approximately linear relation with the single-phase DC magnetic bias, which is exactly consistent with the theoretical analysis. As a result, the proportional relation between the single-phase reactive loss and the single-phase DC magnetic bias is obtained from the simulation results - the proportional factor is respectively 0.77 and 0.76 under no-load condition and rated load condition.