摘要
谐波电流计算是直流输电系统滤波器设计的首要环节。提出一种基于时域分段法的改进快速算法,可以统一求解交流侧特征和非特征谐波电流。根据直流输电系统的特点假设直流输电线路入口处的谐波电压为零,使整流侧和逆变侧的谐波电流计算相互解耦,避免计算过程中对直流线路的建模。精确计算对非特征谐波有重要影响的换相角,保证换相区间和非换相区间的精确划分。计算过程中充分考虑了交流侧负序基波电压、背景谐波电压、触发角不对称、换流变压器三相参数不对称等各种非理想因素的影响,同时计及了直流侧纹波对交流侧谐波电流的影响。通过与PSCAD/EMTDC时域仿真结果对比,证明所提算法速度快、精度高,满足直流工程滤波器设计对谐波电流计算的要求。
Harmonic current calculation is the critical part in the design and configuration of AC filters in HVDC projects. A modified time domain piecewise algorithm was proposed, which can calculate both non-characteristic and characteristic harmonic currents in the AC side simultaneously. At first, based on the characteristics of HVDC systems, the harmonic voltages on the entrance of the DC line were assumed to be zero. This assumption decouples the harmonic current calculation process of the rectifier side and the inverter side, and avoids the modeling of the DC line in the harmonic current calculation. Secondly, the overlap angles were calculated accurately by considering the usual non-ideal factors, including the negative sequence fundamental voltage and the background harmonic voltages on tile AC side, the unsymmetrical firing angles and the imbalance of converting transformer impedances. This ensures an exact partition of the commutation interval and the non-commutation interval, which has an important influence on the non-characteristic harmonic computation. The effect of the DC current ripple was also taken into account in the calculation of the AC side harmonic current. The validity of the proposed method was demonstrated by comparison with the simulation results of PSCAD/EMTDC. It shows the proposed method is fast and accurate, and can meet the requirement of HVDC filter design for practical projects.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2010年第31期92-99,共8页
Proceedings of the CSEE
基金
"十一五"国家科技支撑计划重大项目(2006BAA02A21)~~
