因为按目前的负荷水平来说，一般的城市都有几千台配电变压器和箱式变压器。
Because according to the current load level a city has generally thousands of distribution transformer and box transformer.
认为谐波源来自系统侧，除了非线性负荷外，主要是由大型电力变压器激磁电流所造成。
The harmonic comes from power system side, which is caused mainly by exciting current of the large capacity transformer besides the nonlinear loads.
此外，随着大型变电站的负荷增长，变压器的容量也必须增加。
Furthermore, as the load on a large substation grows, transformer capacity has to BE added.
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