8.13.3.4 Impact of series compensation on protective IED of adjacent linesGUID-DA1DBB5B-0AFD-49F4-87C7-0E8AB5006051 v2Voltage inversion is not characteristic for the buses and IED points closest to theseries compensated line only. It can spread also deeper into the network and thisway influences the selection of protection devices (mostly distance IEDs) onremote ends of lines adjacent to the series compensated circuit, and sometimeseven deeper in the network.en06000616.vsd~~FBEBEAZSAUAA ZLAIAUDDZLBIBUBZSBZLFIF-jXCIEC06000616 V1 EN-USFigure 208: Voltage inversion in series compensated network due to faultcurrent infeedVoltage at the B bus (as shown in figure 208) is calculated for the loss-less systemaccording to the equation below.U U I jX I I j X X I jXB D B LB A B LF C B LB= + ⋅ = +( ) ⋅ −( ) + ⋅EQUATION1911 V2 EN-US (Equation 366)Further development of equation 366 gives the following expressions:U jI X II X XB B LB AB LF C= ⋅ + + ⋅ −( )1EQUATION1912 V2 EN-US (Equation 367)( )01= = ++LBC B LFABXX U XIIEQUATION1913 V1 EN-US (Equation 368)Equation 367 indicates the fact that the infeed current IA increases the apparentvalue of capacitive reactance in system: bigger the infeed of fault current, biggerthe apparent series capacitor in a complete series compensated network. It ispossible to say that equation 368 indicates the deepness of the network to which itwill feel the influence of series compensation through the effect of voltageinversion.It is also obvious that the position of series capacitor on compensated lineinfluences in great extent the deepness of voltage inversion in adjacent system.Line impedance XLF between D bus and the fault becomes equal to zero, if thecapacitor is installed near the bus and the fault appears just behind the capacitor.This may cause the phenomenon of voltage inversion to be expanded very deepSection 8 1MRK 506 369-UEN BImpedance protection384 Line distance protection REL670 2.2 IECApplication manual
