The power quality of the SCOTT traction substation is deteriorated with increscent loads and distinction of two phase condition, including the poor power factor, big voltage fluctuation, high harmonics and negative sequence current. The adopted solution comprises one large power 55 kV thyristor controlled reactor (TCR) and three fixed capacitors (FC). The TCR and two FCs were installed in the burden phase while the other FC was installed in the light phase. On the basis of the topology of the compensation system, the mathematical model of real time reactive power optimization control in the traction substation was invented, and the control of TCR was discussed in detail. Power quality indexes before and after the system was put into operation were compared, the voltage depreciation of the burden phase is decreased from 30％ to 11％, and the power factor is increased from 0.76 to 0.98. At the same time, the negative sequence current is improved, and the efficiency and utilizable capability of the transformer is promoted.%针对斯科特变压器由于运量增大、主变压器的两相工况差异大而造成的电压波动大、功率因数低、谐波和负序电流大的问题,提出在变压器55 kV侧接1个大容量晶闸管控制电抗器支路和3个固定电容补偿支路,其中晶闸管控制电抗器支路和2个固定电容补偿支路安装于重载臂,而另一个固定电容补偿支路安装于轻载臂.结合其拓扑结构,提出以负序电流最小为目标的多约束无功功率优化控制数学模型,并对其控制过程进行详细分析.实际应用表明:该装置解决了重载臂的电能质量问题,使电压跌落从30%减少到11%,功率因数由0.76提高到0.98;并显著减少高压侧的负序电流.提高了变压器的效率和利用率.
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