{
"metadata": {
"name": "",
"signature": "sha256:e3f5e499dcd1ee49e675b7d331eadcbb56a69331fd31c0617d103de1bd691963"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Ch-13, Major Electrical Equipment in Power Plant"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.1 Page 277"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"pg=3000 #kva rating of generators single phase\n",
"xg=0.1 #10%reactanse of generator\n",
"vg=11 #voltage at the terminals of generator\n",
"xbf=5 #reactanse of feeder fron bus to fault\n",
"pb=pg ;vb=vg ;ib=pg/vg #let power and voltage of as respective base then current base\n",
"zb=(vb*10**3)/ib #base impedence\n",
"xpu=xbf/zb #per unit reactance of feeder\n",
"tx=(xg/2)+(xpu) #total reactance \n",
"sckva=pg/tx #short circuit kva is ratio ofpower to total reactance\n",
"sci=sckva/vg #short circuit current\n",
"print 'a'\n",
"print \" p.u.feeder reactor %.3fp.u \\n total reactance is %.3fp.u \\n short circuit kVA %dkVA \\n short circuit current %.1fA\"%(xpu,tx,sckva,sci)\n",
"gz=zb*xg #generator impedence\n",
"tz=(gz/2)+xbf #total impedence\n",
"scc=(vg*10**3)/tz #short circuit current in ampears\n",
"print 'b' \n",
"print \" generator impedence %.3fohm \\n total impedence %.3f ohm \\n short circuit current %.1fA\"%(gz,tz,scc)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a\n",
" p.u.feeder reactor 0.000p.u \n",
" total reactance is 0.050p.u \n",
" short circuit kVA 60000kVA \n",
" short circuit current 5454.5A\n",
"b\n",
" generator impedence 4.000ohm \n",
" total impedence 7.000 ohm \n",
" short circuit current 1571.4A\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.2 page 277"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt\n",
"pa1=20000 ; pa2=30000 #kva in in 3 ph power\n",
"va1=11 ; va2=11 #voltage in kilo volts\n",
"pt1=20000 ; pt2=30000#kva of 3 ph transformer\n",
"vpt1=11 ; vpt2=11#voltage of primery of transformer\n",
"vst1=132 ; vst2=132#voltage of secondary of transformer\n",
"xg1=0.5 ; xg2=0.65 #reactance of generator\n",
"xt1=0.05 ;xt2=0.05 #reactance of transformer with their own kva\n",
"pb=pa2; vbg=va2 ;vbt=vpt2 #assumeing base quantoties\n",
"xtn1=xt1*pb/pa1 ;xtn2=xt2*pb/pa2 #transformer reactance with new base\n",
"xgn1=xg1*pb/pa1; xgn2=xg2*pb/pa2\n",
"xn1=xtn1+xgn1 ;xn2=xtn2+xgn2 #reactancee up to fault from each generator\n",
"xn=(xn1*xn2)/(xn1+xn2) #equalent reactance between generator and fault\n",
"sckva=pb/xn #short circuit KVA\n",
"print '(a)'\n",
"print \" equivalent reactance is %.4f p.u \\n short circuit KVA %dKVA\"%(xn,sckva)\n",
"print '(b)'\n",
"sccb=sckva/(vst1*sqrt(3))\n",
"sccg1=sccb*(xn2/(xn1+xn2))*vst1/vpt1\n",
"sccg2=sccb*(xn1/(xn1+xn2))*vst2/vpt2\n",
"print \" short circuit current on bus bar side %.1fA \\n short circuit current of generator 1 is %.1fA \\n short circuit current of generator 2 is %.1fA \\n\"%(sccb,sccg1,sccg2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a)\n",
" equivalent reactance is 0.3787 p.u \n",
" short circuit KVA 79220KVA\n",
"(b)\n",
" short circuit current on bus bar side 346.5A \n",
" short circuit current of generator 1 is 1908.6A \n",
" short circuit current of generator 2 is 2249.4A \n",
"\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.3 Page 278"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"pa1=20000 ; pa2=30000 #kva in in 3 ph power\n",
"va1=11 ; va2=11 #voltage in kilo volts\n",
"pt1=20000 ; pt2=30000#kva of 3 ph transformer\n",
"vpt1=11 ; vpt2=11#voltage of primery of transformer\n",
"vst1=132 ; vst2=132#voltage of secondary of transformer\n",
"xg1=0.5 ;xg2=0.65 #reactance of generator\n",
"xt1=0.05 ;xt2=0.05 #reactance of transformer with their own kva\n",
"pb=pa2 ;vbg=va2 ;vbt=vpt2 #assumeing base quantoties\n",
"xtn1=xt1*pb/pa1 ;xtn2=xt2*pb/pa2 #transformer reactance with new base\n",
"xgn1=xg1*pb/pa1 ;xgn2=xg2*pb/pa2\n",
"xn1=xtn1+xgn1 ;xn2=xtn2+xgn2 #reactancee up to fault from each generator\n",
"xn=(xn1*xn2)/(xn1+xn2) #equalent reactance between generator and fault\n",
"sckva=pb/xn #short circuit KVA\n",
"pf=50000 #fault kva rating\n",
"xf=pb/pf #reactance from fault\n",
"xx=xf*xn1/(xn1-xf)\n",
"x=xx-xn2 #reactance to be added \n",
"bi=(vst1**2)*1000/(pb)\n",
"xo=x*bi\n",
"print \" reactance to be added in circuit of generator 2 have %.1f p.u. \\n reactance in ohms %.1f\"%(x,xo)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" reactance to be added in circuit of generator 2 have -0.7 p.u. \n",
" reactance in ohms -406.0\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.4 Page 278"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"pa=50; xgb=0.5; xb=0.1 #given power,reactance of generator\n",
"x1=xgb+xb \n",
"x=x1*x1*xgb/(x1*x1+x1*xgb+x1*xgb)\n",
"f=pa/x\n",
"print \" total reactance %.4f.p.u \\n fault MVA %.1fMVA\"%(x,f)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" total reactance 0.1875.p.u \n",
" fault MVA 266.7MVA\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example13_5 Page 279"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"vb=33\n",
"pb=20 ;zb=vb**2/pb #base voltage and base power\n",
"pa1=10 ;pa2=10; xa1=0.08; xa2=0.08 #given power and reactance for different branches\n",
"pbb=20 ;xb=0.06 ;pc=15 ;xc=0.12; pd=20; xd=0.08 \n",
"xab=2.17; xbc=3.26; xcd=1.63; xda=4.35 \n",
"xap1=xa1*pb/pa1 \n",
"xap2=xa2*pb/pa2 ;xap=xap1*xap2/(xap1+xap2)\n",
"xbp=xb*pb/pbb \n",
"xcp=xc*pb/pc \n",
"xdp=xd*pb/pd #generators reactance in per unit\n",
"xabp=round(xab*100/zb)/100 \n",
"xbcp=round(xbc*100/zb)/100 \n",
"xcdp=round(xcd*100/zb)/100 \n",
"xdap=round(xda*100/zb)/100 #reactance in per unit between bus\n",
"def del2star(d12,d23,d31):\n",
" dsum=d12+d23+d31\n",
" s1=d12*d31/(dsum)\n",
" s2=d12*d23/(dsum)\n",
" s3=d31*d23/dsum\n",
" return [s1,s2,s3]\n",
"def star2del(s1,s2,s3):\n",
" d12=s1+s2+(s1*s2)/s3\n",
" d23=s2+s3+(s2*s3)/s1\n",
" d31=s3+s1+(s3*s1)/s2\n",
" return [d12,d31,d23]\n",
"[xac,xrc,xra]=star2del(xcdp,xdap,xdp)\n",
"rc=xrc*xcp/(xrc+xcp)\n",
"ra=xra*xap/(xra+xap)\n",
"[xpr,xpc,xpa]=del2star(xac,rc,ra)\n",
"xf1=xbcp+xpc\n",
"xf2=xpr+xabp\n",
"xf=xf1*xf2/(xf1+xf2)\n",
"xfr=xf+xpa\n",
"xx=xfr*xbp/(xfr+xbp)\n",
"netr=xx #net reactance\n",
"fkva=pb*1000/xx\n",
"print \"the rating of circuit breaker should be %d KVA, or %d MVA\"%(fkva,fkva/1000)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"the rating of circuit breaker should be 671200 KVA, or 671 MVA\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13_6 Page 285"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"p=150 #given ,power\n",
"v=11 #given voltage\n",
"xg=0.12 #reactance of generator\n",
"xb=0.08 #reactance of line\n",
"scca=1/xg\n",
"ms=scca**2\n",
"sccb=1/(xg+xb)\n",
"ms1=sccb**2\n",
"print 'a'\n",
"print \"short circuit current is %.3fp.u \\n ratio of mechanical stress on short circuit to aech. stresses on full load %.2f\"%(scca,ms)\n",
"print 'b'\n",
"print \"short circuit current is with reactor %.3fp.u \\n ratio of mechanical stress on short circuit to aech. stresses on full load with reactor %.f\"%(sccb,ms1)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a\n",
"short circuit current is 8.333p.u \n",
" ratio of mechanical stress on short circuit to aech. stresses on full load 69.44\n",
"b\n",
"short circuit current is with reactor 5.000p.u \n",
" ratio of mechanical stress on short circuit to aech. stresses on full load with reactor 25\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example13_7 Page 286"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import acos, pi, sin, cos, atan\n",
"xf=complex(0,0.04)\n",
"pf=0.8 ;ph=acos(pf)*180/pi\n",
"v=1 ;i=1 #let v and i\n",
"vb=v+i*xf*(complex(cos(ph*pi/180),-sin(ph*pi/180)))\n",
"iv=vb-abs(v) \n",
"print \"bus bar voltage %.4f.p.u at angle %.1f\\nincrease in voltage %.4f =%.4f percent\"%(abs(vb),atan(vb.imag/vb.real)*180/pi,abs(iv),abs(iv*100))"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"bus bar voltage 1.0245.p.u at angle 1.8\n",
"increase in voltage 0.0400 =4.0000 percent\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.8 page 286"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"p1=30 ;x1=0.3 #power and reactance of different sets\n",
"p2=30 ;x2=0.3\n",
"p3=20 ;x3=0.3\n",
"l=10 ;xl=0.04\n",
"pb=p1 ;xp3=x3*pb/p3\n",
"tr=(xp3*x1*x2)/(xp3*x1+xp3*x2+x1*x2)\n",
"sc=pb/tr\n",
"print 'a'\n",
"print \"total reactance %.4f p.u \\n short circuit MVA on l.v.bus %.2fMVA\"%(tr,sc)\n",
"print 'b'\n",
"xlp=xl*pb/l\n",
"trr=tr+xlp\n",
"scc=pb/trr\n",
"print \"total reactance seen from h.v.side of transformer %.2fp.u \\n short circuit MVA %.2fMVA\"%(trr,scc)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a\n",
"total reactance 0.1125 p.u \n",
" short circuit MVA on l.v.bus 266.67MVA\n",
"b\n",
"total reactance seen from h.v.side of transformer 0.23p.u \n",
" short circuit MVA 129.03MVA\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.9 Page 287"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"p1=30 ;x1=0.15; p2=10; x2=0.125 \n",
"pt=10 ;vs=3.3 ;pm=100\n",
"pb=p1 #let base as power of unit 1\n",
"x22=x2*pb/p2; x11=x1*pb/p1\n",
"xx=1/((1/x22)+(1/x11)+(1/x11))\n",
"xl=(pb/pm)-xx\n",
"xt2=xl*pt/pb\n",
"bi=vs**2/pt\n",
"xtt=xt2*bi\n",
"print \" reactance of transformer is %.4f.p.u \\n reactance of transformer on %dMVA base is %.5fp.u. \\n reactance of transformer %.4fohm\"%(xl,pt,xl,xtt)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
" reactance of transformer is -0.0625.p.u \n",
" reactance of transformer on 10MVA base is -0.06250p.u. \n",
" reactance of transformer -0.0227ohm\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13.10 Page 287"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#given #p=power/v=voltage/f=frequency/x=reactance/iff=feeder reactance take off\n",
"pa=20 ;va=11 ;f=50 ;xa=0.2 ;pb=30 ;xb=0.2 ;pf=10 ;xf=0.06; iff=0.5\n",
"pba=20 ;vba=11\n",
"xap=xa*pba/pb\n",
"xfp=xf*pba/pf\n",
"nx=xfp+(xa/2)*(xa/2+xap)/(xa+xap)\n",
"fcp=nx**(-1)\n",
"bc=pba*1000/(va*sqrt(3))\n",
"fc=fcp*bc\n",
"print 'a'\n",
"print \"fault current %.2fohm\"%(fc)\n",
"ic=iff*fcp\n",
"xtx=ic**(-1)\n",
"xn=xtx-nx\n",
"zb=va**2/pba\n",
"xnn=xn*zb\n",
"print 'b'\n",
"print \"reactance required %.4fohm\"%(xnn)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a\n",
"fault current 5524.88ohm\n",
"b\n",
"reactance required 1.1400ohm\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"example 13 11 Page 288"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"n1=5 ;x=0.4 ;d=0.1; g=20 #given\n",
"mva=(g/x)+(g*(n1-1)/(x+n1*d))\n",
"n2=10 #given\n",
"mva2=(g/x)+(g*(n2-1)/(x+n2*d))\n",
"print 'a'\n",
"print \"fault MVA =(g/x)+(g*(n-1)/(x+nd)) \\n fault level is to equal to fault MVA if n=infinity\"\n",
"print 'b'\n",
"print \" MVA=%.2fMVA if n=%d \\n MVA=%.2fMVA if n=%d\"%(mva,n1,mva2,n2)\n",
"fl=g*((1/x)+(1/d))\n",
"print 'c'\n",
"print \"\\nfault level %dMVA\"%(fl)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a\n",
"fault MVA =(g/x)+(g*(n-1)/(x+nd)) \n",
" fault level is to equal to fault MVA if n=infinity\n",
"b\n",
" MVA=138.89MVA if n=5 \n",
" MVA=178.57MVA if n=10\n",
"c\n",
"\n",
"fault level 250MVA\n"
]
}
],
"prompt_number": 11
}
],
"metadata": {}
}
]
}