{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Ch-13, Major Electrical Equipment in Power Plant" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.1 Page 277" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.2 page 277" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.3 Page 278" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ " reactance to be added in circuit of generator 2 have -0.7 p.u. \n", " reactance in ohms -406.0\n" ] } ], "source": [ "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" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.4 Page 278" ] }, { "cell_type": "code", "execution_count": 4, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ " total reactance 0.1875.p.u \n", " fault MVA 266.7MVA\n" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example13_5 Page 279" ] }, { "cell_type": "code", "execution_count": 5, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "the rating of circuit breaker should be 671200 KVA, or 671 MVA\n" ] } ], "source": [ "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" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13_6 Page 285" ] }, { "cell_type": "code", "execution_count": 6, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example13_7 Page 286" ] }, { "cell_type": "code", "execution_count": 7, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "bus bar voltage 1.0245.p.u at angle 1.8\n", "increase in voltage 0.0400 =4.0000 percent\n" ] } ], "source": [ "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))" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.8 page 286" ] }, { "cell_type": "code", "execution_count": 8, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.9 Page 287" ] }, { "cell_type": "code", "execution_count": 9, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13.10 Page 287" ] }, { "cell_type": "code", "execution_count": 10, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "a\n", "fault current 5524.88ohm\n", "b\n", "reactance required 1.1400ohm\n" ] } ], "source": [ "from math import sqrt,pi\n", "#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)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## example 13 11 Page 288" ] }, { "cell_type": "code", "execution_count": 11, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "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" ] } ], "source": [ "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)" ] } ], "metadata": { "kernelspec": { "display_name": "Python 2", "language": "python", "name": "python2" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 2 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython2", "version": "2.7.9" } }, "nbformat": 4, "nbformat_minor": 0 }