L14 - ECE 524: Transients in Power Systems Session 14; Page...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
ECE 524: Transients in Power Systems Session 14; Page 1/13 Spring 2012 ECE 524: Lecture 14 Define units: MW 1000kW  MVA MW  MVAr MVA  f 60Hz  ω 2 π f  ω 376.99 rad s μ sec 10 6 s  t 0 1.5 μ sec 1 60 sec   Capacitor Switching Example For the system below find the following: 1. Worst case inrush current when closing into C 2 with C 1 in the circuit and C 2 discharged. Compute without a preinsertion resistor jX s C 2 C 1 Assume source and capacitors are Y connected. V LL 34.5kV  RMS Capacitor Banks: Q 1 18MVAr  at 34.5kV Q 2 10MVAr  at 34.5kV L 2 19.2 μ H  buswork between caps Source I sc 25kA  Determine circuit parameters: Find capacitance using: Q V LL  2 X c = X c1 V LL 2 Q 1  X c1 66.13 Ω X c2 V LL 2 Q 2  X c2 119.03 Ω C 1 1 ω X c1  C 1 40.11 μ F C 2 1 ω X c2  C 2 22.29 μ F
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ECE 524: Transients in Power Systems Session 14; Page 2/13 Spring 2012 Find source impedance using: I sc V ln X s = X s V LL 3 I sc  X s 0.797 Ω L s X s ω  L s 2.113 mH R s 0ohm  no source resistance L s C 2 C 1 L 1 Equivalent circuit: V m V LL 2 3  V m 28.17 kV ϕ 90deg  v s t () V m sin ω t ϕ  U VS 2.11mH 19.2uH S1 I C2 40.11uF C1 22.29uF Approximate Solution: As a first pass we could look at just the transient circulating between the two capacitors Series combination of capacitors: C eq C 1 C 2 C 1 C 2  C eq 14.33 μ F f 01 1 2 π L 2 C 1 C 2 C 1 C 2  f 01 9596.15 1 s Likely to be damped severly by a resistance
Background image of page 2
ECE 524: Transients in Power Systems Session 14; Page 3/13 Spring 2012 f 02 1 2 π L s C 1 C 2   f 02 438.26 1 s True double frequency solution Determine natural frequencies from characteristic equation 0s ω 4 1 L s C 1 1 L 1 C 2 1 L 2 C 1 s ω 2 1 L s C 1
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/28/2012 for the course ECE 524 taught by Professor Staff during the Spring '08 term at Idaho.

Page1 / 13

L14 - ECE 524: Transients in Power Systems Session 14; Page...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online