牵引网高次谐波对高低压三相系统的渗透特性

为研究牵引网高次谐波对高低压三相系统的影响,建立了阻抗匹配平衡变压器谐波模型,分析了高次谐波对公共电网高压三相系统的渗透特性;建立了牵引变电所用逆Scott变压器谐波模型,分析了高次谐波对牵引变电所低压三相系统的渗透特性;对牵引侧高次谐波含量较高的牵引变电所进行了测试,分析了谐波实测数据,并与谐波模型分析结果进行了对比;提出了一种适用于牵引变电所低压三相系统的Y型阻波高通滤波器滤波方案,并研制了一套滤波试验装置.研究结果表明,牵引网高次谐波对公共电网高压三相系统的渗透较小,但会明显渗透到牵引变电所低压三相系统;滤波装置投入运行后,牵引变电所低压三相系统a相电压谐波畸变率由12.25%降为1.94%,b、c两相电压谐波畸变率也明显降低,滤波装置有效的滤除了高次谐波,改善了低压三相系统供电质量. 

Permeability Characteristics of High-Order Harmonics of Traction Network for Three-Phase Power System

In order to study the influences of the high order harmonics of traction network on three-phase power system, the harmonic model of impedance-matching balanced transformer was established to analyze the permeability characteristics of high-order harmonics for public grid high-voltage three-phase system, and the harmonic model of the inverse Scott transformer was established to analyze the permeability characteristics of high-order harmonics for the low-voltage three-phase system of traction substation. The traction substation with severe harmonic distortion was measured, and the harmonic measured data were analyzed and compared with those resulted from harmonic models of impedance-matching balanced transformer and inverse Scott transformer. A filtering scheme based on Y-type wave-trap high-pass filter was proposed which is applied to the low-voltage three-phase system of traction substation, and a set of filtering devices was developed. The results show that the high-order harmonics less penetrate into the high-voltage three-phase system, but significantly into the low voltage three-phase system of traction substation. After filtering, the harmonic distortion rate of a-phase voltage at traction substation is reduced from 12.25% to 1.94%, and the harmonic distortion rates of b-phase and c-phase are also significantly reduced. This indicates that the developed device can filter the high-order harmonics and effectively improve the power supply quality of the low-voltage three-phase system.