Impact of modelling of transmission network components on the - PDF document

Impact of modelling of transmission network components on the emission limits for distorting loads in HV system Rizah Memisevic 17 February 2011 Contents 1

Frequency scan analysis 1000 100 Self Impedance Networkimpedance Angle 900 80 800 60 700 40 Self Impedanze (Ohm) 600 20 500 Angle (deg) Pi model Network Impedance, Magnitude in Ohm Pi model Networkimpedance, Angle in deg 0 Distributed Model Network Impedance, Magnitude 1 2.5 4 5.5 7 8.5 10 11.5 13 14.5 16 17.5 19 20.5 22 23.5 25 26.5 28 29.5 31 32.5 34 35.5 37 38.5 40 41.5 43 44.5 46 47.5 49 Distributed Model Networkimpedance, Angle in deg 400 in Ohm -20 300 -40 200 -60 100 -80 0 1 2.5 4 5.5 7 8.5 10 11.5 13 14.5 16 17.5 19 20.5 22 23.5 25 26.5 28 29.5 31 32.5 34 35.5 37 38.5 40 41.5 43 44.5 46 47.5 49 -100 Harmonic Harmonic 2

1000 100 Self Impedanze Netwrok impedance Angle 900 80 800 60 700 40 600 Self Impedance (Ohm) 20 500 Angle (deg) Distributed Model Network Impedance, Magnitude in Ohm 0 Distributed Model Networkimpedance, Angle in deg Freq.Dep.Tr. Model Network Impedance, Magnitude 1 2.5 4 5.5 7 8.5 10 11.5 13 14.5 16 17.5 19 20.5 22 23.5 25 26.5 28 29.5 31 32.5 34 35.5 37 38.5 40 41.5 43 44.5 46 47.5 49 Freq.Dep.Tr. Model Networkimpedance, Angle in deg 400 in Ohm -20 300 -40 200 -60 100 -80 0 1 2.5 4 5.5 7 8.5 10 11.5 13 14.5 16 17.5 19 20.5 22 23.5 25 26.5 28 29.5 31 32.5 34 35.5 37 38.5 40 41.5 43 44.5 46 47.5 49 -100 Harmonic Harmonic The skin effect of the transmission line • r e the external radius of conductor (m) r i the internal radius of conductor (m) • • J 0 is the Bessel function of the first kind and zero order J’ 0 is the derivative of the Bessel function of the first kind and zero • order N 0 is the Bessel function of the second kind and zero order • • J’ 0 is the derivative of the Bessel function of the second kind and zero order σ c • is the conductivity of the conductor material at the average conductor temperature f is frequency (Hz) • � 0 • is the permeability of free space 3

Correction factors for skin effect in overhead lines Voltage (kV) Harmonic order Resistance NGC 400, 275 h≤4.21 4.21<h ≤7.76 h>7.76 NGC 132 EDF 400, 225 h≤4 4<h<8 h>8 EDF 150, 90 Correction for skin effect in overhead lines according to EDF & NGC Corrections for skin effect in overhead lines 4 EDF 400kV & 225 kV NGC 400kV & 275kV EDF & NGC 150kV & 132kV & 90kV 3.5 3 Rh/R1 2.5 2 1.5 1 0 5 10 15 20 25 30 35 40 45 50 Harmonic 4

Voltage (kV) Coefficient a Coefficient b NGC 400, 275 0.2401 0.6434 NGC 132 0.0985 0.6562 EDF 400, 225 0.2286 0.6486 EDF 150, 90 0.0985 0.6562 Correction for skin effect in over headlines - EDF 400 kV & 225 kV / Frequency polynomial function Correction for skin effect in over headlines - NGC 400 kV & 275 kV / Frequency polynomial function Corrections for skin effect in overhead lin es - Frequency polynomial characteristic 4 EDF 400kV & 225 kV Freque ncy po l ynomial characteristic 3 .5 3 Rh/R1 2 .5 2 Co rrections for skin e ffect in ove rhead lines - Fre quency po lyno mial characte ristic 4 1 .5 NGC 400kV & 275kV Frequency polynom ial characteristic 3.5 1 0 5 10 15 20 25 30 35 4 0 45 5 0 Harmon ic 3 Rh/R1 2.5 2 1.5 1 0 5 10 15 20 25 30 35 40 45 50 Harmonic 5

Correction for skin effect in over headlines - EDF / NGC 150 kV / 132 kV and 90 kV - Frequency polynomial function Corrections for skin effect in overhead lines - Frequency polynomial characteristic 2.4 EDF & NGC 150kV & 132kV & 90kV Frequency polynomial characteristic 2.2 2 1.8 Rh/R1 1.6 1.4 1.2 1 0 5 10 15 20 25 30 35 40 45 50 Harmonic 900 100 Self impedance Network Impedance Angle 800 80 700 60 600 40 Self Impedance (Ohm) Freq. dep. resistance of Tr. Network Impedance, 500 Magnitude in Ohm Freq. dep. resistance of Tr. Networkimpedance, 20 Angle (deg) Angle in deg Series Resistances as the Vector Characteristics Series Resistances as the Vector Characteristics 400 Network Impedance, Magnitude in Ohm Networkimpedance, Angle in deg 0 Series Resistance as the Frequency Polynomial Series Resistance as the Frequency Polynomial 1 16 31 46 61 76 91 106 121 136 151 166 181 196 211 226 241 256 271 286 301 316 331 346 361 376 391 406 421 436 451 466 481 Characteristics Networkimpedance, Angle in deg Characteristics Network Impedance, Magnitude in 300 Ohm -20 200 -40 100 -60 0 1 2.5 4 5.5 7 8.5 10 11.5 13 14.5 16 17.5 19 20.5 22 23.5 25 26.5 28 29.5 31 32.5 34 35.5 37 38.5 40 41.5 43 44.5 46 47.5 49 -80 Harmonic Harmonic 6

Conclusions related to the self impedances of the busbar concerning different modelling approaches of the skin effect: There is no significant impact of the modelling of the skin effect on the • complex self impedance for harmonics lower than 8 th harmonic. The impact of the skin effect on the self impedance of the busbar • increase with the order of the harmonic. Skin effect has the biggest impact on the busbar self impedance at • resonant frequencies. At resonant frequencies, the amplitude of the self impedance can be reduced up to 50% if the skin effect of the transmission lines has been modelled. Taking this into account the modelling of the skin effect of transmission lines can be seen as being critical for all frequency scan analysis. • Modelling of skin effect does not have any impact on the resonance frequencies of the self impedances • There are no significant differences between two analysed modelling methodologies of the skin effect: the frequency polynomial functions and vector characteristics. The frequency polynomial function is simpler and much easier to apply which is a major advantage of this methodology. • We notice that modelling of skin effect has an impact on the network impedance angle; however we are not able to identify any importance of this on the filter design or harmonic allocation. Emission limits for distorting loads in HV - EHV systems Stage 1 • Stage 2 • 1 is the considered node and 2, 3, … the other nodes • S t1 , S t2 , S t3 , … the total available power of the network at • the point of common coupling (total supply capability) • h harmonic order K h2-1 , K h3-1 , K h4-1 , … the influence coefficients. The • influence coefficient K hj-i is the harmonic voltage of order h which is caused at node i when 1 p.u. harmonic voltage of order h is applied at node j. 7

E UHi is the voltage emission limit of a consumer i at • harmonic h L hHV is the planning level of the h th harmonic in HV or • EHV systems see Standard S i is the rating of the consumer • α is the summation law exponent, see Standard • F HV is the coincidence factor for HV loads, typical values • are between 0.4 and 1. B h is the background harmonic level higher than normal • share • S B is the already connected power responsible for background level B h K hi-j is the greatest influence coefficient greater than 1. • 8

Voltage emission limits, 40 MVA load Voltage emission limits with and without resonance effect, 40 MVA load 1.2 1 Voltage Emission Limits Voltage Emission Limits - Vector Chacteristics 0.9 Allocated Limit (%) Vector Characteristics 1 Allocate d Limit(%) Pi Line Model 0.8 Allocate d Limit(%) Distr. Line Model Allocated Limit(%) (Resonance taken into account) Vector Characteristics Allocate d Limit(%) Freq.Dep.R.Tr. 0.7 0.8 Allocate d Limit(%) Polynomial Characteristics 0.6 Allocate d Limit (%) Vector Characteristics ated Limit (%) Allocated Limit (%) 0.6 0.5 Alloc 0.4 0.4 0.3 0.2 0.2 0.1 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Harmonic Harmonic 250 Current Emission Limits 200 150 Current Limit (A) Allocated Limit(A) Allocated Limit(A) & Res. 100 50 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Harmonic Current emission, 40 MVA load E IHi is the current emission limit of a consumer i at harmonic h Z hi is the self impedance at node i at harmonic h 9

Voltage emission limits, 500 MVA load Current emission limits, 500 MVA 1.6 250 Voltage Emission Limit Current Emission Limits 1.4 200 1.2 1 150 Allocated Limit (%) Curre nt Limit (A) 0.8 Allocated Limit(%) Allocated Limit(A) Allocated Limit(%) (Resonance taken into account) Allocated Limit(A) & Res. 100 0.6 0.4 50 0.2 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Harmonic Harmonic Conclusions Questions Rizah Memisevic Phone Number : +61 7 3866 1432 Fax Number : +61 7 3866 1222 Mobile Number: +61 0421650682 E-mail : rmemisevic@powerlink.com.au 10