高压直流换流站换流系统宽频建模研究

Wide-band Modeling of Converter Systems in HVDC Converter Stations

高压直流(high voltage DC,HVDC)换流站电磁骚扰主要由阀体内的晶闸管在周期性的导通和关断过程中产生。该骚扰中的高频分量通过辐射和传导2种形式可能会对换流站内的通讯设备、保护与控制系统和载波系统以及换流站附近的无线电台站等产生影响,所以,建立换流系统的宽频等效电路模型对该骚扰进行计算和预测,研究其时频特性是进行干扰机理分析的前提条件。该文给出了HVDC换流站各主要设备的建模方法及其等效电路,包括阀组件、换流变压器、平波电抗器、滤波器等。其中,阀组件内各元件的阻抗通过网络分析仪测量,然后通过矢量匹配进行零极点提取,最后通过布隆法进行网络综合得到阀组件各器件的宽频等效电路。应用有限元方法计算了阀塔以及散热片的寄生电容参数。以阀塔作为整体,基于PSCAD/EMTDC建立了HVDC换流站换流系统宽频仿真模型。在此基础上,研究了传导电磁骚扰特性。计算结果和测量结果的比较,验证了该文建模方法的正确性。

Electromagnetic disturbance （EMD） is mainly caused by the periodic valve switching in HVDC converter station. This disturbance can cause high frequency conducted and radiative interference to the adjacent communication, computer equipment, carrier system and radio stations. So a wide-band model of converter system is necessary to predict the characteristic of the EMD source. Methods of modeling and the equivalent circuits of the main equipment in HVDC converter stations are presented, including valve section, converter transformer, smoothing reactor, filters, surge arrester, tubular bus and so on. The modeling method of valve components is based on the impedance measurements. Vector fitting is used to approximate the rational functions and Brune method is applied to provide equivalent circuits suitable for EMTP or PSCAD. The stray capacitances of the valve tower and the heat sinks are calculated by finite element method. The whole wide-band model is simulated by PSCAD/EMTDC. Based on this model, the characteristic of EMD under normal operation condition is calculated. For validity, a comparison between the simulated and measured is conducted.