Sequence Impedances of Transmission Lines
description
Transcript of Sequence Impedances of Transmission Lines
Sequence Impedances of Transmission Lines
jXm jXm jXs Ia Va jXm Va’ Vb jXs Ib Vb’ Vc Vc’ jXs Ic Ia+Ib+Ic Ground Va = jXsIa + jXmIb + jXmIc + Va’ Vb = jXsIb + jXmIa + jXmIc + Vb’ Vc = jXsIc + jXmIa + jXmIb + Vc’ Put into Matrix Notation: Va Va’ Xs Xm Xm Ia Vb - Vb’ = j Xm Xs Xm Ib Vc Vc’ Xm Xm Xs Ic
Zph
Recall that: Z012 = A-1
Zabc A
Z0=zs+2zm
Z1=zs-zm
Z2=zs-zm
4
Symmetrical components of generator
Symmetrical components of generator
• Z1 = synchronous reactance (Xd)
transient reactance (Xd’)
subtransient reactance (Xd’’)• Depends on the analysis required
(breaker setting, fault analysis, transient stability studies, steady state analysis)
Z2 = Xd’’
Z0 = leakage reactance (Xl)
Symmetrical components of transformer
• Although Z0 slightly differ from other two, it is
customary to takeZ1 = Z2 = Z0 = Xl
7
Symmetrical components of transformer (zero)
•