在城鄉電網改造過程中，為了改善功率因數，提高系統運行的經濟性，各臺區均在配電變壓器的低壓側加裝了并聯電容器以進行無功補償，但是調查中發現低壓電容器的損壞較為嚴重。其主要原因是非線性負荷的影響。
什么是非線性負荷？
所(suo)謂非(fei)線性(xing)負荷(he)就是(shi)在正(zheng)弦(xian)供(gong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓(ya)下(xia)產(chan)生(sheng)非(fei)正(zheng)弦(xian)電(dian)(dian)(dian)(dian)(dian)流(liu)或者(zhe)正(zheng)弦(xian)供(gong)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)下(xia)產(chan)生(sheng)非(fei)正(zheng)弦(xian)電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)用電(dian)(dian)(dian)(dian)(dian)設(she)(she)備(bei)。諧波(bo)則是(shi)畸變波(bo)行的(de)(de)(de)(de)周(zhou)期(qi)分(fen)量(liang)，其(qi)頻率是(shi)基波(bo)頻率的(de)(de)(de)(de)整(zheng)數倍。非(fei)線性(xing)負荷(he)將會在電(dian)(dian)(dian)(dian)(dian)網中產(chan)生(sheng)諧波(bo)電(dian)(dian)(dian)(dian)(dian)流(liu)和(he)(he)諧波(bo)電(dian)(dian)(dian)(dian)(dian)壓(ya)（諧波(bo)源(yuan)）。目(mu)前諧波(bo)源(yuan)主要為(wei)電(dian)(dian)(dian)(dian)(dian)流(liu)源(yuan)。電(dian)(dian)(dian)(dian)(dian)力系(xi)統穩(wen)態(tai)方式下(xia)的(de)(de)(de)(de)諧波(bo)均來(lai)自各種諧波(bo)源(yuan)。隨著技術進(jin)步，用電(dian)(dian)(dian)(dian)(dian)設(she)(she)備(bei)種類日(ri)趨復雜，投入電(dian)(dian)(dian)(dian)(dian)網的(de)(de)(de)(de)非(fei)線性(xing)負荷(he)的(de)(de)(de)(de)污染(ran)日(ri)益(yi)嚴重，對各種電(dian)(dian)(dian)(dian)(dian)氣設(she)(she)備(bei)產(chan)生(sheng)了不同程度的(de)(de)(de)(de)影響和(he)(he)危(wei)害。
對電容器的影響
電容器比其他電氣設備更容易受諧波影響和損壞的原因：
一是其阻抗和頻率成反比；
二是呈容性阻抗特性。
諧波對電容器的影響有以下幾個方面：
a.電容器工作電壓的升高
b.電容器過電流和過負荷
c.電容器的介質損耗增加
d.諧振引(yin)起(qi)的諧波放大(da)
為(wei)了(le)保證并聯(lian)電(dian)(dian)容器安全運(yun)行，提(ti)高電(dian)(dian)容器的使用壽命，必須(xu)在(zai)低壓(ya)電(dian)(dian)網中采取措施(shi)，將諧波(bo)電(dian)(dian)流及(ji)諧波(bo)電(dian)(dian)壓(ya)限制在(zai)規定(ding)(ding)范圍(wei)之內。比如(ru)為(wei)電(dian)(dian)容器串聯(lian)一(yi)定(ding)(ding)電(dian)(dian)抗率的電(dian)(dian)抗器或者加裝有源電(dian)(dian)力濾波(bo)器。
STF有源電力濾波器基于(yu)高速的(de)濾(lv)(lv)波(bo)補償技術(shu)，消除各種形式的(de)諧波(bo)，可應(ying)用于(yu)各種在諧波(bo)污染的(de)工況，尤其適用于(yu)快(kuai)速變(bian)化(hua)的(de)負載(zai)。具(ju)有響(xiang)(xiang)應(ying)速度快(kuai)、濾(lv)(lv)波(bo)范圍(wei)廣、濾(lv)(lv)波(bo)效(xiao)果高、不受系統參(can)數影響(xiang)(xiang)等(deng)特點，達到改善電(dian)能(neng)(neng)質量，降(jiang)低電(dian)網損耗、提高供電(dian)利用效(xiao)率和(he)帶(dai)載(zai)能(neng)(neng)力的(de)目的(de)，是理想的(de)濾(lv)(lv)波(bo)產品。
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