并联电容器无功补偿方案

精选文档 精选文档 可编辑可编辑课程设计并联电容器无功补偿方案设计指导老师：江宁强1010190456尹兆京目 录TOC\o"1-2"\h\z\u绪论 3引言 3无功补偿的提出 3本文所做的工作 4无功补偿的认识 4无功补偿装置 4无功补偿方式 4无功补偿装置的选择 5投切开关的选取 5无功补偿的意义 7电容器无功补偿方式 7串联无功补偿 7并联无功补偿 7确定电容器补偿容量 8案例分析 8利用并联电容器进行无功功率补偿，对变电站调压 8利用串联电容器，改变线路参数进行调压 18利用并联电容器进行无功功率补偿，提高功率因素 205总结 27绪论引言随着现代科学技术的发展和国民经济的增长，电力系统发展迅猛，负荷日益自然功率因素低，影响发电机的输出功率;降低有功功率的输出;影响变电、输电的供电能力;降低有功功率的容量;增加电力系统的电能损耗;增加输电线路无功补偿的提出本文所做的工作主要对变电站并联电容器无功补偿作了简单的分析计算,提出了目前在变电站无功补偿实际应用中计算总容量与分组的方法,本文主要作了以下几个方面的工作:对无功补偿作了简单的介绍，尤其是电容器无功补偿，选取了相关的案例进行了简单的计算和分析。无功补偿的认识无功补偿装置SCR、GTR、GTO主要有以下三大类型:1、具有饱和电抗器的静止无功补偿装置；2、晶闸管控制电抗器、晶闸管投切电容器，这两种装置统称为SVC3、采用自换相变流技术的静止无功补偿装置——高级静止无功发生器。无功补偿方式改善电源电压质量的无功补偿电容器。其主要用于城市高压配电中。高压集中补偿。高压集中补偿是指将电容器装于变电站或用户降压变电站6kV～10kV高压母线的补偿方式;电容器也可装设于用户总配电室低压母低压分散补偿。低压分散补偿就是根据个别用电设备对无功的需要量将单投资大，对变速运行，正反向运行，点动、堵转、反接制动的电机则不适应。低压集中补偿。低压集中补偿是指将低压电容器通过低压开关接在配电变低压补偿的优点:接线简单、运行维护工作量小，使无功就地平衡，从而提高配变利用率，降低网损，具有较高的经济性，是目前无功补偿中常用的手段之一。无功补偿装置的选择选择哪一种补偿方式，还要依环境等情况而定，对所补偿的线路要有所了解。投切开关的选取对于无功功率补偿装置来说，选择何种电容器投切执行机构，对整套装置的安全运行是至关重要的。目前用于电容器投切的执行元件主要有：系统工作较平稳的场合。晶闸管电子开关，此类产品具有电压过零投入、电流过零切除、反应速复合开关，复合开关的工作原理是将晶闸管和交流接触器并接，电容器命长，价格也相对适中。要保证投切开关长期、可靠的运行，选用时必须注意以下几点：(1)投切开关的额定电流必须与投切的电容的额定电流匹配。(2)投切开关的接线端子过流要满足额定电流。(3)投切开关的端子的接线必须牢固可靠。无功补偿的意义电容器无功补偿方式电容器无功补偿可以分为串联无功补偿和并联无功补偿。串联无功补偿QcX/V>0.95PR/V并联无功补偿QcX/V损及提高用户功率因数方面，并联补偿要比串联补偿优越的多。确定电容器补偿容量无功补偿容量宜按无功功率曲线或无功补偿计算方法确定，其计算公式如下:QC=p(tgφ1－tgφ2)或是QC=pqc式中:Qc:补偿电容器容量;P:负荷有功功率;COSφ1:补偿前负荷功率因数;COSφ2:补偿后负荷功率因数;qc:无功功率补偿率，kvar/kw。案例分析利用并联电容器进行无功功率补偿，对变电站调压110KV70Km0.263+j0.423Ω/Km.变电所有两台变压器并联运行，其参数:SN=31.5MV·A，VN110±2*2.5%KV/11KV,V%=10.5。变电所最大40+j30MV·A30+j20MV·A2.5%~7.5%（0.66KV、40KV·A）。电路图如下：根据调压要求确定变电所二次侧母线上所需补偿的电容器最小容量；解：（1）变电所二次侧母线上所需补偿的电容器最小容量ZL 11

jx1

)9.205j14.8051 V2

1 10.51102

20.167( )X T 2

S 100SN

2 10031.5总阻抗ZRjX9.205j34.972()SmaxSmin

40230211022023021102

(9.205j34.972)1.902j7.226(MVA)(9.205j34.972)0.989j3.757(MVA)于是 S1maxSmaxSmax41.902jS1minSminSmin30.989jV'2max

V1

P1max

RQ1maxV1

X11641.9029.20537.22634.972101.452(kV)116V'2min

V1

P1min

RQ1minV1

X11630.9899.20523.75734.972106.379(kV)116按最小负荷时无补偿确定变压器的分接头电压'V V2NV'

2

11106.379108.85(kV)t V2min

101.075最接近的抽头电压为110kV，由此可得降压变压器变比为k1101011补偿容量：Qc

V X

(V

V'2maxkk

3.072(Mvar)取补偿容量Qc=3Mvar校验变电所二次侧母线电压：Scmax

402(303)21102

(9.205j34.972)1.772jS1cmax

40j(303)21.772j6.73141.772j33.731(MVA)V'2cmax

V1

P1c

RQ1cV1

X11641.7729.20533.73134.972102.8(kV)116故V

V' 102.8 kV2cmax )2cmax

k 10VV'2cmin2cmin kVV'2cmin2cmin k106.37910.638(kV10变电所二次侧母线电压满足调压要求。3Mvar3103VN

0.173(A)若使用提供的电容器构建：单个电容器的额定电流及额定容抗分别为：

Q

40 =60.61(A)INc V

Nc 0.66I INc C

max

Ncm1又VNc

0.66kV

n 100.66

15.16总个数N 3 75，不经济330.0433选择其他电容器：BFM浸苄基甲苯,全膜.

11/2

Kv,200Kvar,单相,横放型,11/3Q则I Nc 11/3QNc VNc

200

31.49AI

C

m1又VNc

11/n

1.57211/3总个数N 315，为保险起见m=3,n=511/30.2变电所的负荷在40+j30MV·A——30+j20MV·A之间。1、设定电压偏移随着负荷的加重逐渐减小，由EXCEL计算得如下图首段电压功率损耗压功率损耗总功率末端电压V1P1Q2△S-P△S-QP2Q2V2'111630200.9889673.75732230.9889723.75732106.3785211631211.0665634.05212832.0665625.05213105.902611632221.147204.3584933.147226.3584105.4233249411633231.2308834.67642134.2308827.67642104.9397511634241.3176085.00590935.3176129.00591104.4526611635251.4073765.34695936.4073830.34696103.9619711636261.5001875.69956937.5001931.69957103.4674811637271.596046.0637438.596033.0637102.969

补偿前要求补偿后要求补偿后补偿容量 电压偏移441911638281.6949376.43947239.6949434.43947102.46721011639291.7968776.82676640.7968835.82677101.961511640301.901867.2256241.901837.2256101.45211621电压功率损耗总功率末端电压V2c'Qc△Sc-P△Sc-QPcQcV2''补偿前补偿后1107.53.4473790.8931053.3931230.8931119.94574107.53526.378%7.535%21073.3575240.9678623.67713831.9678621.31961107.03575.903%7.036%3106.53.2797081.0456043.97249933.045622.69279106.53625.423%6.536%41063.2137731.1262774.27899734.1262824.06522106.03674.940%6.037%5105.53.1595571.2098294.59643135.2098325.43687105.53724.453%5.537%61053.11691.2962094.92460736.2962126.80771105.03773.962%5.038%7104.53.0856441.3853665.26333737.3853728.17769104.53833.467%4.538%81043.0656281.4772545.6124438.4772529.54681104.03882.969%4.039%9103.53.0566931.5718255.97173939.5718230.91505103.53952.467%3.539%101033.0586781.6690366.34106640.6690432.28239103.04021.961%3.040%11102.53.0714231.7688426.72025541.7688433.64883102.5411.452%2.541%根据计算可得，若设定电压偏移随着负荷的加重逐渐减小，则只需并联3Mvar的电容器，当负荷加重使末端电压低于102.96时，投入电容器，当负荷加重到最大时，可以将电压偏移由1.452%提升到2.541%。R=9.205X=34.972首段电补偿前要求负载2R=9.205X=34.972首段电补偿前要求负载压功率损耗总功率末端电压电压V1P1Q2△S-P△S-QP2Q2V2'V2c'111630200.9889673.75732230.9889723.75732106.3785102.5211631211.0665634.05212832.0665625.05213105.9026102.5311632221.1472024.35849433.147226.35849105.423102.5411633231.2308834.67642134.2308827.67642104.9397102.5511634241.3176085.00590935.3176129.00591104.4526102.5611635251.4073765.34695936.4073830.34696103.9619102.5补偿后补偿容量补偿后补偿容量电压偏移711636261.5001875.69956937.5001931.69957103.4674102.5811637271.596046.0637438.5960433.06374102.9691102.5911638281.6949376.43947239.6949434.43947102.4672102.51011639291.7968776.82676640.7968835.82677101.9615102.51111640301.901867.2256241.9018637.22562101.4521102.51211641312.0098857.63603543.0098938.63604100.9389102.51311642322.1209548.05801144.1209540.05801100.4221102.51411643332.2350658.49154845.2350741.4915599.90146102.51511644342.352228.93664746.3522242.9366599.37713102.51611645352.4724179.39330647.4724244.3933198.84908102.51711646362.5956589.86152648.5956645.8615398.31731102.51811647372.72194110.3413149.7219447.3413197.7818102.51911648382.85126810.8326550.8512748.8326597.24257102.52011649392.98363711.3355551.9836450.3355596.69962102.52111650403.1190511.8500253.1190551.8500296.15293102.5功率损耗总功率末端电压Qc△Sc-P△Sc-QPcQcV2''补偿前补偿后1-11.36751.4331835.44500431.4331836.81255102.40736.38%2.41%2-9.97281.4608675.55018532.4608736.52299102.41315.90%2.41%3-8.567141.4898035.66011733.489836.22725102.42065.42%2.42%4 -7.150551.5200085.77487634.5200135.92543102.42984.94%2.43%5 -5.723041.5515065.89454235.5515135.61758102.44084.45%2.44%6 -4.28461.5843166.01919536.5843235.3038102.45343.96%2.45%7 -2.835241.6184616.14891937.6184634.98416102.46773.47%2.47%8 -1.374961.6539626.28379938.6539634.65876102.48372.97%2.48%9 0.0962431.6908446.42392239.6908434.32768102.50122.47%2.50%10 1.5783721.7291296.56937740.7291333.99101102.52031.96%2.52%11 3.0714231.7688426.72025541.7688433.64883102.5411.45%2.54%12 4.5753981.8100076.8766542.8100133.30125102.56310.94%2.56%13 6.0902961.8526497.03865843.8526532.94836102.58680.42%2.59%14 7.6161171.8967947.20637544.8967932.59026102.6119-0.10%2.61%15 9.1528621.9424687.37990245.9424732.22704102.6384-0.62%2.64%16 10.700531.9896987.5593446.989731.85881102.6663-1.15%2.67%17 12.259122.0385117.74479348.0385131.48567102.6956-1.68%2.70%18 13.828642.0889367.93636749.0889431.10773102.7262-2.22%2.73%19 15.409072.1409998.13416950.14130.7251102.7581-2.76%2.76%20 17.000432.1947318.3383151.1947330.33788102.7912-3.30%2.79%21 18.602722.2501618.54890252.2501629.94618102.8255-3.85%2.83%并联电容器组的最大容量：由计算可得当负荷最大时，所并联的电容器容量最大Qc=18.60272Mvar,并联电容器组的投入条件。33并联电容器组的分组33选取并联电容器：BFM浸苄基甲苯,全膜.

11/2

Kv,200Kvar,单相,横放型,Icmax采取等容量分配方式：

Q23VQ23V310

1.039(A)11/ 3QI Nc 11/ 3QNc VNc

200

31.49A

C

m 1又 VNc

11/3kV n

1.57211/3总个数N 1890个，分成45组（m=45）,编号为1,2,3，……，45，11/30.2每组2个（n=2）,补偿范围从0到18Mvar，精度为0.4Mvar。根据上表，当电压变化时，改变电容器的投入容量即可。如当末端电压为101.96kV,要求电压为105.25kV，需要投入9.89Mvar，需要投入的组数为m’=9.89/0.4=24.7，取m’=25，投入10Mvar补偿容量功率损耗补偿后总功率末端电压电压偏移Qc△Sc-P △Sc-QPc QcV2''补偿前 补偿后101.43172 5.43944740.43172 24.43945105.42351.96% 5.42%1. 并联电容器组的切除条件当末端电压的电压偏移超过要求时，需要通过切除部分电容器适当降低末端电压。例如本案例中，首端电压为116V时，若负载为50+j40MVA，补偿后电压偏移为2.83%，若首端电压变为120V时，补偿后电压偏移为7.26%，若电压偏移要求限度为5%，那么这个时候电压偏移就超过了要求，这时候需要切除部分电容器。利用串联电容器，改变线路参数进行调压110KV70Km0.263+j0.423Ω/Km.变电所有两台变压器并联运行，其参数:SN=31.5MVA，VN110±2*2.5%KV/11KV,V%=10.5。变电所最大40+j30MV30+j20MVA2.5%~7.5%（0.66KV、40KVA）。60.66KV40KVA（不记线路功率损耗）电路图为：解：ZL=L1*(r1+jx1)=18.410+29.610(Ω)最大负荷为40+j30MW·A△V=PRQXV1

=4018.4103029.610=14.006（kV）116允许电压损耗：△Vpevm=116*6%=6.96(kV)所需电容器的容抗：X-6.96)116

=27.245(Ω)C Q 30线路最大负荷电流：P2+Q23VNP2+Q23VN

= 103=262.433(A)503503110INC=Qnc=40

=60.61(A)Vnc 0.66X =Vnc=0.661000

==10.89(Ω)NC Inc 60.61电容器并组的组数应大于m=Icmax

=262.432

=4.329 m=5每组个数应大于nIcmax

Inc 60.61=262.4321089

=4.330 n=5Inc 0.661000则电容器组总数量为：3mn=3*5*5=75（个）总容量为：Qc=75*Qcn=75*40*10-3=3.00MVar验算电压损耗：Xc=nXnc=10.89（Ω）m=PRQ(X-Xc)=4018.410029.610-10.89（）V1 116△V%=11.19*100%=9.6<6%(高于允许值)110m=5，n=13

=nm

=13*10.89（Ω）△V=6.68(kv)5△V%=5.76<6%（符合要求）3mn=3*13*5=195（个） 若采用并联电容器补偿，为达到同样效果，所需容量为PRQQ)X 40141030-Q2610 C c 6.96kVperm

V1 116Q 27.604MvarcQc串联/Qc并联=7.8/27.604=28.26%可见串联电容器仅为并联电容器的28.26%。4.3利用并联电容器进行无功功率补偿，提高功率因素题目：（1）35KV双电源变电站10KV供电变电站电缆供电负荷位置统计资料如图：说明：数据单位（km）变电站负荷（不含输电线路）反馈资料如下：名称有功负荷（kw）同期启动系数自然功率因数目标功率因数矿机厂13500.920.75≥0.92电机厂9500.950.67≥0.91炼油厂10500.870.74≥0.92汽车厂10000.880.76≥0.93化工厂9000.860.82≥0.95名称名称站用电（kw）目标功率因数变电站12≥0.9名称名称型号电压（KV）电阻（Ω/km）电抗（Ω/km）电缆ZLQ2-3×170100.450.084000KVA（4）10KV电缆充电功率忽略不计为计算方便令1,2,3,4,5字符分别代表矿机厂，电机厂，炼油厂，汽车厂，化工厂计算：负荷反馈资料中的最大有功负荷计算依据最大有功功率的计算公式：Pmax

KPJ式中：P 为最大有功负荷，其国际单位为瓦（w）。maxK 为同期启动系数（又名需用系数），1。JP 为统计有功负荷，其国际单位为瓦（w）。J说明：1,2,3,4,5P1maxP2maxP3maxP4maxP5max

KP1 1JKP2KP3JKP4KP5J

13500.929500.95902.510500.87913.510000.88880.09000.86774.0

(kw)(kw)(kw)(kw)(kw)功率因数角的计算依据功率因数利用反三角函数求出功率因数角，其计算公式为：cosA 则 arccosA式中：cos为功率因数符号，单位为1。A1。为功率因数角，单位为度。arc为反三角函数的代号。自然功率因数角：cos12cos2∵ cos3cos4cos5

0.75 120.76 20.74 ∴ 30.76 40.82 5

arccos0.750.723arccos0.760.707arccos0.740.738 arccos0.760.707arccos0.820.609

tan1tan2tan3tan4tan5

0.8820.8550.9090.8550.698目标功率因数角：cos0.92 arccos0.920.403

tan0.42612cos2∵ cos3cos4cos5

120.91 20.92 ∴ 30.93 40.95 5

arccos0.910.428arccos0.920.403 arccos0.930.376arccos0.950.318

1tan2tan3tan4tan5

0.4560.4260.3950.329最大无功负荷的计算依据最大无功负荷计算公式：Qmax

Pm