是在DC輸電系統中，為了過濾DC控制系統產生的諧波，避免對交流輸電系統的不利影響，補償DC控制系統消耗的無功功率，必須在DC系統運行過程中投入一定數量的交流濾波器。交流濾波器由電容、電阻和電阻串并聯組成。

濾(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)原(yuan)理：當整流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)高于電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)時，電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)充電(dian)(dian)(dian)(dian)(dian)(dian)；當整流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低于電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)時，電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)。在(zai)充放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)過程中，輸(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)基本穩定。濾(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)大，可獲(huo)得相對穩定的直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)濾(lv)(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)(dian)路利用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)充放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)，使輸(shu)出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)平穩。