低压柜为什么要进行电容补偿？

发布日期：2019-06-25 10:42 来源：//www.9notesstudycircle.com 点击：

低压柜(ju)为什么要进行电容补偿？

1、电力(li)电容器的补(bu)偿原(yuan)理

电容器在原理上相当于产生容性无功电流的发电机。其无功补偿的原理是把具有容性功率负荷的装置和感性功率负荷并联在同一电容器上，能量在两种负荷间相互转换。这样，电网中的变压器和输(shu)(shu)电线路的负荷降低，从而输(shu)(shu)出有(you)功能力增加。在输(shu)(shu)出一定有(you)功功率(lv)的情况下，供电系(xi)统(tong)的损耗降低。比较起来电容(rong)器是减(jian)轻(qing)变压器、供电系(xi)统(tong)和工业配电负荷的简(jian)便、经济(ji)的方法。因此，电容(rong)器作为(wei)电力系(xi)统(tong)的无功补偿(chang)势在必行。当前，采用并联电容(rong)器作为(wei)无功补偿(chang)装置已经非常普遍

2、电力电容(rong)器(qi)补偿的(de)特点(dian)

优点

电(dian)力电(dian)容器无功补偿装(zhuang)置(zhi)具(ju)有(you)安装(zhuang)方便(bian)，安装(zhuang)地点增(zeng)减方便(bian)；有(you)功损耗小(仅为额定(ding)容量的(de)0.4 %左(zuo)右);建设周期短(duan)；投资小；无旋(xuan)转(zhuan)部件，运(yun)行维护(hu)简便(bian)；个别电(dian)容器组(zu)损坏，不影响整个电(dian)容器组(zu)运(yun)行等优点。

缺点

电力(li)电容器无功(gong)补(bu)(bu)偿装置的(de)缺点有(you)：只能进行(xing)有(you)级(ji)调节(jie),不能进行(xing)平滑(hua)调节(jie);通(tong)风不良，一旦电容器运(yun)行(xing)温度(du)高于70 ℃时，易发生膨胀爆(bao)炸；电压特性不好，对短路稳定性差，切除后有(you)残余电荷；无功(gong)补(bu)(bu)偿精度(du)低，易影响补(bu)(bu)偿效果；补(bu)(bu)偿电容器的(de)运(yun)行(xing)管理困难及电容器安全运(yun)行(xing)的(de)问题未受(shou)到(dao)重(zhong)视等。

3、无功补偿方式

高压分散(san)补偿

高压(ya)分散补偿实际就是在(zai)单台变压(ya)器高压(ya)侧安装的(de)，用以改善电源电压(ya)质量的(de)无功补偿电容器。其主要用于城市高压(ya)配电中。

高(gao)压(ya)集(ji)中(zhong)补偿

高(gao)压(ya)(ya)集(ji)中(zhong)(zhong)补(bu)(bu)偿(chang)是(shi)指将电(dian)(dian)容器(qi)装于(yu)(yu)变电(dian)(dian)站(zhan)或(huo)用(yong)户(hu)(hu)降(jiang)压(ya)(ya)变电(dian)(dian)站(zhan)6 kV～10 kV高(gao)压(ya)(ya)母(mu)(mu)线(xian)(xian)(xian)的(de)补(bu)(bu)偿(chang)方式(shi)；电(dian)(dian)容器(qi)也可装设于(yu)(yu)用(yong)户(hu)(hu)总配(pei)(pei)电(dian)(dian)室低压(ya)(ya)母(mu)(mu)线(xian)(xian)(xian),适用(yong)于(yu)(yu)负荷较(jiao)(jiao)(jiao)集(ji)中(zhong)(zhong)、离配(pei)(pei)电(dian)(dian)母(mu)(mu)线(xian)(xian)(xian)较(jiao)(jiao)(jiao)近、补(bu)(bu)偿(chang)容量(liang)(liang)较(jiao)(jiao)(jiao)大的(de)场所，用(yong)户(hu)(hu)本(ben)身又有一定的(de)高(gao)压(ya)(ya)负荷时，可减少对电(dian)(dian)力系统无功的(de)消耗(hao)并起到一定的(de)补(bu)(bu)偿(chang)作(zuo)用(yong)。其优点是(shi)易(yi)于(yu)(yu)实行自动投切(qie)，可合理(li)地提高(gao)用(yong)户(hu)(hu)的(de)功率因素，利用(yong)率高(gao),投资较(jiao)(jiao)(jiao)少，便于(yu)(yu)维护，调节(jie)方便可避免过补(bu)(bu)，改善电(dian)(dian)压(ya)(ya)质量(liang)(liang)。但这种补(bu)(bu)偿(chang)方式(shi)的(de)补(bu)(bu)偿(chang)经济(ji)效益较(jiao)(jiao)(jiao)差(cha)。

低压分散补(bu)偿

低(di)压(ya)(ya)分散补(bu)(bu)偿就是(shi)根据个别用电设(she)(she)(she)备(bei)对(dui)(dui)无功的(de)(de)需要量(liang)，将单台(tai)或多台(tai)低(di)压(ya)(ya)电容器组(zu)，分散地安装在用电设(she)(she)(she)备(bei)附近(jin)，以补(bu)(bu)偿安装部位前边的(de)(de)所有高低(di)压(ya)(ya)线(xian)路和变(bian)(bian)(bian)压(ya)(ya)器的(de)(de)无功功率。其优(you)点(dian)(dian)是(shi)用电设(she)(she)(she)备(bei)运(yun)行时(shi)，无功补(bu)(bu)偿投(tou)入(ru)，用电设(she)(she)(she)备(bei)停(ting)运(yun)时(shi)，补(bu)(bu)偿设(she)(she)(she)备(bei)也(ye)退出，可(ke)减(jian)少配电网和变(bian)(bian)(bian)压(ya)(ya)器中(zhong)的(de)(de)无功流动(dong)，从而减(jian)少有功损(sun)耗(hao)；可(ke)减(jian)少线(xian)路的(de)(de)导线(xian)截(jie)面(mian)及变(bian)(bian)(bian)压(ya)(ya)器的(de)(de)容量(liang),占(zhan)位小。缺点(dian)(dian)是(shi)利用率低(di)、投(tou)资(zi)大,对(dui)(dui)变(bian)(bian)(bian)速运(yun)行，正反(fan)向运(yun)行，点(dian)(dian)动(dong)、堵转、反(fan)接制动(dong)的(de)(de)电机则不(bu)适应。

低压集(ji)中补偿

低(di)(di)(di)(di)压(ya)(ya)(ya)集中补(bu)偿(chang)是指(zhi)将低(di)(di)(di)(di)压(ya)(ya)(ya)电(dian)(dian)容(rong)器通(tong)过低(di)(di)(di)(di)压(ya)(ya)(ya)开关接(jie)(jie)在配电(dian)(dian)变压(ya)(ya)(ya)器低(di)(di)(di)(di)压(ya)(ya)(ya)母线侧，以(yi)无(wu)功补(bu)偿(chang)投切装置(zhi)(zhi)作(zuo)为控(kong)制保护装置(zhi)(zhi)，根据(ju)低(di)(di)(di)(di)压(ya)(ya)(ya)母线上的(de)(de)(de)(de)无(wu)功符合(he)而(er)直(zhi)接(jie)(jie)控(kong)制电(dian)(dian)容(rong)器的(de)(de)(de)(de)投切。电(dian)(dian)容(rong)器的(de)(de)(de)(de)投切是整(zheng)组进行(xing)，做(zuo)不(bu)到(dao)平(ping)滑的(de)(de)(de)(de)调节。低(di)(di)(di)(di)压(ya)(ya)(ya)补(bu)偿(chang)的(de)(de)(de)(de)优点(dian)：接(jie)(jie)线简单、运行(xing)维(wei)护工(gong)作(zuo)量小，使无(wu)功就(jiu)地平(ping)衡，从而(er)提高配变利用(yong)率，降低(di)(di)(di)(di)网(wang)损，具有较高的(de)(de)(de)(de)经济性，是目(mu)前无(wu)功补(bu)偿(chang)中常用(yong)的(de)(de)(de)(de)手段之一。

4、电容器补偿(chang)容量的计(ji)算

无功补(bu)偿(chang)容(rong)量宜按无功功率曲线(xian)或无功补(bu)偿(chang)计算方法确(que)定，其(qi)计算公式如下(xia)：

QC=p(tgφ1-tgφ2)或(huo)是QC=pqc(1)

式中：

Qc：补偿电容器容量；

P：负荷有功功率；

COSφ1：补偿前(qian)负荷功率因数；

COSφ2：补偿(chang)后负(fu)荷功率因(yin)数；

qc：无功功率补(bu)偿率,kvar/kw。

5、电力(li)电容(rong)器的安全运(yun)行

1、允许运(yun)行电流(liu)

正常运行(xing)时(shi),电(dian)容器应在(zai)额定电(dian)流(liu)(liu)下运行(xing)，大运行(xing)电(dian)流(liu)(liu)不(bu)得超(chao)过额定电(dian)流(liu)(liu)的1.3倍，三相电(dian)流(liu)(liu)差不(bu)超(chao)过5 %。

2、允许运行电压

电(dian)(dian)(dian)容器(qi)对电(dian)(dian)(dian)压(ya)十(shi)分敏感，因电(dian)(dian)(dian)容器(qi)的(de)损(sun)耗与电(dian)(dian)(dian)压(ya)平方成正比，过(guo)电(dian)(dian)(dian)压(ya)会使电(dian)(dian)(dian)容器(qi)发热严重，电(dian)(dian)(dian)容器(qi)绝缘会加速(su)老化，寿命缩短,甚至电(dian)(dian)(dian)击穿。因此，电(dian)(dian)(dian)容器(qi)装置(zhi)应在额(e)定(ding)(ding)(ding)电(dian)(dian)(dian)压(ya)下运行，一般不宜(yi)超(chao)过(guo)额(e)定(ding)(ding)(ding)电(dian)(dian)(dian)压(ya)的(de)1.05倍，高运行电(dian)(dian)(dian)压(ya)不宜(yi)超(chao)过(guo)额(e)定(ding)(ding)(ding)电(dian)(dian)(dian)压(ya)的(de)1.1倍。当母(mu)线超(chao)过(guo)1.1倍额(e)定(ding)(ding)(ding)电(dian)(dian)(dian)压(ya)时，须采(cai)取降温措施(shi)。

3、谐波问题

由于电(dian)(dian)(dian)(dian)容器(qi)(qi)回路(lu)是一个LC电(dian)(dian)(dian)(dian)路(lu)，对于某些谐(xie)波(bo)(bo)(bo)容易产生谐(xie)振，易造成(cheng)高(gao)次谐(xie)波(bo)(bo)(bo)，使电(dian)(dian)(dian)(dian)流增加(jia)和电(dian)(dian)(dian)(dian)压升高(gao)。且谐(xie)波(bo)(bo)(bo)的这种电(dian)(dian)(dian)(dian)流对电(dian)(dian)(dian)(dian)容器(qi)(qi)非常有害，极容易使电(dian)(dian)(dian)(dian)容器(qi)(qi)击穿引起相间(jian)短路(lu)。因(yin)此，当(dang)电(dian)(dian)(dian)(dian)容器(qi)(qi)在正(zheng)常工作时，在必(bi)要时可(ke)在电(dian)(dian)(dian)(dian)容器(qi)(qi)上串联适当(dang)的感抗(kang)值(zhi)的电(dian)(dian)(dian)(dian)抗(kang)器(qi)(qi)，以(yi)限制谐(xie)波(bo)(bo)(bo)电(dian)(dian)(dian)(dian)流。

4、继电保护问题

继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)(bao)(bao)护(hu)主(zhu)要(yao)(yao)(yao)由(you)继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)(bao)(bao)护(hu)成套装置(zhi)(zhi)(zhi)(zhi)(zhi)实(shi)现(xian)，目(mu)前(qian)国内(nei)几个知名电(dian)(dian)(dian)(dian)(dian)(dian)气厂(chang)家(jia)生产的(de)(de)继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)(bao)(bao)护(hu)装置(zhi)(zhi)(zhi)(zhi)(zhi)技术都已(yi)经非(fei)常成熟，安(an)全稳(wen)(wen)定、功能强大(da)。继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)(bao)(bao)护(hu)装置(zhi)(zhi)(zhi)(zhi)(zhi)可以有(you)效的(de)(de)切(qie)除故障电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)，是保(bao)(bao)(bao)(bao)证电(dian)(dian)(dian)(dian)(dian)(dian)力系统(tong)安(an)全稳(wen)(wen)定运行的(de)(de)重要(yao)(yao)(yao)手段。主(zhu)要(yao)(yao)(yao)的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)保(bao)(bao)(bao)(bao)护(hu)措(cuo)施有(you)：①三段式(shi)过流(liu)保(bao)(bao)(bao)(bao)护(hu)；②为(wei)防(fang)止系统(tong)稳(wen)(wen)态过压(ya)造成电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)损坏而(er)设置(zhi)(zhi)(zhi)(zhi)(zhi)的(de)(de)过电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)(bao)(bao)护(hu)；③为(wei)避免系统(tong)电(dian)(dian)(dian)(dian)(dian)(dian)源短暂停投引(yin)起电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)瞬(shun)时重合(he)造成的(de)(de)过电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)损坏而(er)设置(zhi)(zhi)(zhi)(zhi)(zhi)的(de)(de)低电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)(bao)(bao)护(hu)；④反映(ying)电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)组中电(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)(de)内(nei)部击(ji)穿故障而(er)配置(zhi)(zhi)(zhi)(zhi)(zhi)的(de)(de)不平(ping)衡(heng)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)(bao)(bao)护(hu)、不平(ping)衡(heng)电(dian)(dian)(dian)(dian)(dian)(dian)流(liu)保(bao)(bao)(bao)(bao)护(hu)或三相差电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)保(bao)(bao)(bao)(bao)护(hu)。

5、合闸问题

电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)组禁止带(dai)电(dian)(dian)(dian)(dian)重(zhong)合闸。主要是因电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)放(fang)电(dian)(dian)(dian)(dian)需要一定(ding)时(shi)间，当(dang)电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)组的(de)开关跳(tiao)闸后，如(ru)果马(ma)上重(zhong)合闸，电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)是来(lai)不及放(fang)电(dian)(dian)(dian)(dian)的(de)，在电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)中就可能(neng)残存着与重(zhong)合闸电(dian)(dian)(dian)(dian)压极性(xing)相反(fan)的(de)电(dian)(dian)(dian)(dian)荷，这将使合闸瞬间产生很大的(de)冲击电(dian)(dian)(dian)(dian)流(liu)，从而造(zao)成(cheng)电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)外壳膨胀(zhang)、喷油(you)甚(shen)至爆炸。所以，电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)组再次(ci)合闸时(shi)，必须(xu)在断路器(qi)(qi)(qi)断开3 min之后才可进(jin)行。因此(ci)，电(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)不允许装设自(zi)动重(zhong)合闸装置，相反(fan)应装设无压释(shi)放(fang)自(zi)动跳(tiao)闸装置。

一(yi)些终端变(bian)电(dian)站往(wang)往(wang)配置(zhi)有(you)备用电(dian)源自(zi)动(dong)(dong)投(tou)切(qie)装(zhuang)置(zhi)，装(zhuang)置(zhi)动(dong)(dong)作将故障(zhang)电(dian)源切(qie)除，然后经过(guo)短暂延时投(tou)入备用电(dian)源，在这个过(guo)程中,如果电(dian)容(rong)器组(zu)有(you)低(di)压自(zi)投(tou)切(qie)功能(neng)，那么电(dian)容(rong)器组(zu)将在短时间内(nei)再次合上(shang)，这就会发生(sheng)以上(shang)所(suo)说的(de)(de)故障(zhang)。所(suo)以，安装(zhuang)有(you)备用电(dian)源自(zi)动(dong)(dong)投(tou)切(qie)装(zhuang)置(zhi)的(de)(de)系统与(yu)电(dian)容(rong)器组(zu)的(de)(de)投(tou)切(qie)问题，应值(zhi)得充分的(de)(de)重视。

6、允许(xu)运行温度(du)

电(dian)容(rong)器(qi)(qi)正常(chang)工(gong)作时，其周围额定环境温(wen)度(du)一般为40 ℃～-25 ℃；其内部介(jie)质的(de)温(wen)度(du)应低于65 ℃，高不得超过(guo)70 ℃，否则(ze)会引起热击穿，或(huo)是(shi)(shi)引起鼓(gu)肚现(xian)象。电(dian)容(rong)器(qi)(qi)外壳的(de)温(wen)度(du)是(shi)(shi)在介(jie)质温(wen)度(du)与环境温(wen)度(du)之间，不应超过(guo)55 ℃。因此，应保持(chi)电(dian)容(rong)器(qi)(qi)室内通风(feng)良(liang)好，确保其运行温(wen)度(du)不超过(guo)允(yun)许值。

7、运(yun)行中(zhong)的放电声(sheng)问题

电容(rong)(rong)器(qi)(qi)(qi)在(zai)(zai)运行时(shi)，一(yi)般是没有声音的(de)，但在(zai)(zai)某(mou)些情况(kuang)下，其在(zai)(zai)运行时(shi)也(ye)会存在(zai)(zai)放电声的(de)问题。如(ru)电容(rong)(rong)器(qi)(qi)(qi)的(de)套管(guan)露天放置时(shi)间(jian)过长时(shi)，一(yi)旦(dan)雨水进入两层套管(guan)之(zhi)间(jian),加上电压(ya)后，就有可(ke)能(neng)产生放电声；当电容(rong)(rong)器(qi)(qi)(qi)内(nei)缺油(you)时(shi)，易使其套管(guan)的(de)下端露出(chu)油(you)面(mian)，这时(shi)就有可(ke)能(neng)发(fa)出(chu)放电声；当电容(rong)(rong)器(qi)(qi)(qi)内(nei)部若有虚焊(han)或脱焊(han)，则会在(zai)(zai)油(you)内(nei)闪络放电；当电容(rong)(rong)器(qi)(qi)(qi)的(de)芯子与(yu)外壳接触不良时(shi)，会出(chu)现浮动(dong)电压(ya)，引起放电声。

一(yi)旦出现以上几种(zhong)出现放(fang)电(dian)(dian)声状(zhuang)况，应针对每种(zhong)情况做出处理(li)，即其处理(li)方法依次为(wei)：将电(dian)(dian)容器(qi)停运(yun)并放(fang)电(dian)(dian)后把外(wai)套管(guan)卸出，擦干重新装好(hao)；添加同种(zhong)规(gui)格的电(dian)(dian)容器(qi)油(you)；如放(fang)电(dian)(dian)声不止，应拆开修理(li)；将电(dian)(dian)容器(qi)停运(yun)并放(fang)电(dian)(dian)后进行处理(li)，使其芯子和外(wai)壳接触好(hao)。

8、爆炸问题

电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)在(zai)运行(xing)(xing)过程中(zhong)，如出现电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)内部元件击穿(chuan)、电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)对外壳(qiao)绝缘损(sun)(sun)坏、密封(feng)不(bu)(bu)良和漏油(you)、鼓(gu)(gu)(gu)肚(du)和内部游离(li)、鼓(gu)(gu)(gu)肚(du)和内部游离(li)、带(dai)电(dian)(dian)(dian)(dian)(dian)荷合闸或是(shi)温度过高(gao)、通风不(bu)(bu)良、运行(xing)(xing)电(dian)(dian)(dian)(dian)(dian)压过高(gao)、谐波分量过大、操作过电(dian)(dian)(dian)(dian)(dian)压等情(qing)(qing)况(kuang)(kuang),都有(you)可(ke)能引起电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)损(sun)(sun)坏爆炸。为预防电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)爆炸事故，正常情(qing)(qing)况(kuang)(kuang)下，可(ke)根据每(mei)组相(xiang)电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)通过的(de)(de)电(dian)(dian)(dian)(dian)(dian)流量的(de)(de)大小(xiao)，按1.5倍～2倍，配(pei)以快速熔(rong)断器(qi)(qi)(qi)(qi)，若电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)被击穿(chuan)，则快速熔(rong)断器(qi)(qi)(qi)(qi)会(hui)熔(rong)化(hua)而切断电(dian)(dian)(dian)(dian)(dian)源，保(bao)护电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)不(bu)(bu)会(hui)继续产生热量；在(zai)补(bu)偿柜(ju)上(shang)每(mei)相(xiang)安装(zhuang)电(dian)(dian)(dian)(dian)(dian)流表(biao)，保(bao)证每(mei)相(xiang)电(dian)(dian)(dian)(dian)(dian)流相(xiang)差(cha)不(bu)(bu)超过±5 %，若发现不(bu)(bu)平(ping)衡，立即退出运行(xing)(xing)，检(jian)查电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)；监视电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)的(de)(de)温升情(qing)(qing)况(kuang)(kuang)；加强(qiang)对电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)组的(de)(de)巡检(jian),避(bi)免出现电(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)(qi)(qi)(qi)漏油(you)、鼓(gu)(gu)(gu)肚(du)现象，以防爆炸。