基于LC滤波的10kV配电变压器低压侧整流融冰谐波抑制研究

Study on Rectifying De-icing Harmonic Suppression of Low-voltage Side in 10kV Distribution Transformer Based on LC Filter

每年覆冰季节期间,穿越高海拔地区的10 kV导线会覆冰,供电可靠性受冰害影响明显。近年来,利用已有台区配电变压器低压侧作为融冰电源,通过三相全控整流实现该电源点大号侧10 kV导线停电直流融冰的方法,因其具有融冰电流连续可调,体积小,成本低等特点,已逐步推广使用。但是,融冰时整流装置将在交流侧产生奇次谐波。受台区配变短路阻抗和额定容量影响,不同配变的谐波电流允许值是不一致的。当配变低压侧谐波电流超出允许值时,将影响配电变压器使用寿命和台区用户设备正常工作。本文对常用不同容量的配变低压侧谐波电流谐波允许值进行了计算,提出了一种配变整流融冰谐波抑制措施,并开展了直流融冰时配变低压侧谐波抑制仿真分析与试验验证。从仿真与试验结果可知,该措施能够满足100~630 kVA的配电变压器融冰时低压侧谐波抑制的需求,可供覆冰季节配电线路融冰作业时参考。

During the icing season every year,the 10 kV conductors crossing high altitude areas are likely iced and the power supply reliability is significantly affected by the ice.In recent years,the method of the power off DC ice-melting on the large side of 10 kV conductor of the power point,which uses the low-voltage side of existing distribution transformer(LSDT)as the ice-melting power supply and through three-phase fully controlled rectifier,has been gradually promoted and used due to its such features as continuous adjustable ice-melting current,small volume and low cost.However,the rectifying device will generate odd harmonics at AC side in ice-melting.The allowable harmonic current of different distribution transformer is not identical due to the influence of short-circuit impedance and rated capacity of the station distribution transformer.When the harmonic current at the low voltage side of distribution transformer exceeds the allowable value,the service life of the distribution transformer and the normal operation of the user’s equipment in the station will be affected.In this paper,the allowable harmonic values of harmonic current at the low voltage side of distribution transformer with different capacities are calculated.A kind of ice-melting harmonic suppression measure of distribution transformer is proposed and the simulation analysis of low voltage side of distribution transformer in ice-melting is developed.It is known from the simulation and test results that the measures can meet the needs of harmonic suppression of low voltage side in case of ice-melting by 100~630 kVA distribution transformer and can provide reference for the ice-melting operation of distribution conductor in the ice season.