1
Analysis of the Energiza2on Test of 2600-­‐
km Long AC-­‐Link Composed of Similar Transmissions Lines MSc Student Elson Costa Gomes
Prof. Dr. Maria Cristina Tavares
IEEE 2011 Electrical Power and Energy Conference
2
Introduc2on • In Brazilian system, with 60 Hz of fundamental frequency, the half-­‐wavelength corresponds to a transmission line of 2500 km. • AC transmission with a liJle more than half-­‐wavelength always presents voltage gain close to 1 at no loaded line. • Very stable working with a electrical length around 190 degrees. Behaves like a short line. • Low overvoltages for switching transients such as for energiza2on maximum around 1.95 pu. • A cost 20% lower when compared to DC-­‐Link transmission of similar power capacity and 75% lower when compared to tradicional AC systems. IEEE 2011 Electrical Power and Energy Conference
3
Proposed AC-­‐Link Test IEEE 2011 Electrical Power and Energy Conference
4
Brazilian Electrical System IEEE 2011 Electrical Power and Energy Conference
5
System Characteris2cs North-South 1 - SIL=209.5 Ω
Zero
Unitary
Resistence
[Ω/km]
0.37138
Unitary
Indutance
[mH/km]
4.11662
Unitary
Capacitance
[µF/km]
0.00725
Positive/Negative
0.01589
0.0700
0.01612
Sequence
North-South 2 - SIL=208.5 Ω
North-South 1
Zero
Unitary
Resistence
[Ω/km]
0.34822
Unitary
Indutance
[mH/km]
3.74452
Unitary
Capacitance
[µF/km]
0.00946
Positive/Negative
0.01602
0.71089
0.01634
Sequence
North-South 2
North East-South East - SIL=212.5 Ω
Zero
Unitary
Resistence
[Ω/km]
0.34821
Unitary
Indutance
[mH/km]
3.75767
Unitary
Capacitance
[µF/km]
0.00934
Positive/Negative
0.01602
0.724032
0.01603
Sequence
North East-South East
IEEE 2011 Electrical Power and Energy Conference
6
Frequency Analysis • Two-­‐port Transmission Line Representa2on • To analyze the energiza2on switching two boundary condi2ons were imposed: – The sending end voltage was established (U1); – The current at the open receiving end (I2) is zero. IEEE 2011 Electrical Power and Energy Conference
7
Frequency Analysis • HWL+ alterna2ves: – The AC-­‐Link Test formed by trunks North-­‐South I, North-­‐South II and North East-­‐South East, totaling 2600 km. – The HWL+ line supposedly to have North-­‐South I tower configura2on with 2600 km – NS-­‐1. – The HWL+ line supposedly to have North-­‐South II tower configura2on with 2600 km – NS-­‐2. – The HWL+ line supposedly to have North East-­‐South East tower configura2on with 2600 km – NE-­‐SE. • All lines was supposed ideally transposed. IEEE 2011 Electrical Power and Energy Conference
8
M and O Constants for Posi2ve Sequence IEEE 2011 Electrical Power and Energy Conference
9
M and O Constants for Zero Sequence IEEE 2011 Electrical Power and Energy Conference
10
Sensi2vity Analysis for Different Trunks • Evaluate the possibility to have AC-­‐Links formed by lines that are not similar as the ones that compose the AC-­‐Link Test. • The base line structure was NS-­‐1 and its external phases distance to the center of the line was increased to obtain new lines with SIL differences of 5 Ω. IEEE 2011 Electrical Power and Energy Conference
11
New Line Structure Characteris2cs Unitary
Resistance
[Ω/km]
Unitary
Indutance
[mH/km]
Unitary
Capacitance
209.5942
0.01589
0.7070
16.1225
5.175
215.5625
0.01589
0.7274
15.6803
Line 2
5.625
219.2771
0.01590
0.7402
15.4183
Line 3
6.3
224.4922
0.01592
0.7581
15.0666
Line 4
7.2
230.8504
0.01594
0.7802
14.6612
Line 5
7.875
234.2248
0.01596
0.7955
14.3973
Line 6
8.775
240.5975
0.01599
0.8144
14.0879
Line 7
9.675
245.5091
0.01602
0.8318
13.8189
Line 8
10.575
250.0194
0.01605
0.8479
13.5829
Horizontal
Distance
[m]
SIL [Ω]
NS-1
4.5
Line 1
Silhoutte
[µF/km]
IEEE 2011 Electrical Power and Energy Conference
12
Sensi2vity Analysis for Different Trunks • The sensi2vity analysis consisted of varying the sec2on lenght and the sec2on posi2on inside the AC-­‐Link Test of the trunk with higher SIL. • Each trunk was replaced by the transmission lines created before. While one trunk was varied the other two were replaced by NS-­‐1 line parameters. IEEE 2011 Electrical Power and Energy Conference
13
Length Varia2on of Trunks IEEE 2011 Electrical Power and Energy Conference
14
Time Domain Simula2on • Simulations performed with PSCAD/EMTDC.
• Cases:
– AC-Link Test;
– HWL+ NS-1;
– AC-Link Test with replacement of trunk 2 for line 2
(220 Ω);
– AC-Link Test with replacement of trunk 2 for line 8
(250
Ω);
• For all simulations the sending end voltage was adjusted
so that the voltage at the receiving end was set to 1.0 pu
in steady state.
IEEE 2011 Electrical Power and Energy Conference
15
Time Domain Simula2on Voltage at receiving end of AC-Link Test during
energization maneuver.
Voltage at receiving end of AC-Link Test with
replacement of trunk 2 for the line 2 (SIL of
220 Ω) during energization maneuver.
Voltage at receiving end of NS-1 line during
energization maneuver.
Voltage at receiving end of AC-Link Test with
replacement of trunk 2 for the line 8 (SIL of
250 Ω) during energization maneuver.
IEEE 2011 Electrical Power and Energy Conference
16
Conclusions • The use of lines with similar electrical parameters, such as the AC-­‐Link Test, is suitable for field energiza2on test. • For the observed case, in which the lines have SIL between 209 and 212 Ω, the replacement of any part of the line with trunks that has a SIL of up to 220 Ω was considered acceptable, not changing the switching overvoltages and not disturbing the voltages signals in steady state. • It is possible to use lines with higher SIL differences if the lenght of this trunk not exceed about 400 km. IEEE 2011 Electrical Power and Energy Conference