WREF 01 Paper # 048 Harmonics Issues that Limit Solar Photovoltaic Generation on Distribution Circuits Ketut Dartawan Ricardo Austria, Le Hui and Mark Suehiro* Pterra Consulting Maui Electric Company* May 17 th, 01 Denver, CO
Voltage Magnitude Voltage Magnitude I. Harmonic is Distortion of Ideal Waveform.0 Ideal Fundamental.0 Fundamental + Harmonic Voltages Versus Angles Distorted 1.0 1.0 0.0 0.0-1.0-1.0 -.0 0 90 180 70 360 450 540 630 70 -.0 0 90 180 70 360 450 540 630 70 Angle (degree) Angle (degree)
Voltage Magnitude 3 Distortion Caused by Harmonic Source Ideal Waveform 60 Hz + 3 rd Harmonic Source 180 Hz 3 x 60 Hz.0 1.0 0.0 Fundamental + Harmonic Voltages Versus Angles -1.0 Distorted Waveform -.0 0 90 180 70 360 450 540 630 70 Angle (degree)
Voltage Magnitude 4 Distortion Caused by Harmonic Sources Ideal Waveform 60 Hz + Multiple Harmonic Sources 3 rd,5 th,7 th,9th.0 1.0 0.0 Fundamental + Harmonic Voltages Versus Angles -1.0 Distorted Waveform -.0 0 90 180 70 360 450 540 630 70 Angle (degree)
5 Harmonics from renewable resources Power Plant Transmission Lines Photovoltaic Panels DC AC Power Inverters Distribution Substation Harmonics
6 Harmonics are risky/hazardous to power systems overheating equipment over-voltages interferences with communication systems mis-operation of sensitive loads etc
7 IEEE standards IEEE standard 519: IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems, 199 IEEE standard 1547: IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems, 003
8 Total harmonics distortion (THD) I THD I I 3 I I 4 1 I n V THD V V 3 V V 1 4 V n
9 Criteria - IEEE Std 519 199 Harmonic Voltage Distortion in % at PCC.3-69 kv 69-161 kv > 161 kv Maximum for Individual Harmonic 3.0 1.5 1.0 Total Harmonic Distortion (THD) 5.0.5 1.5 *: only portions are shown here IEEE Std 1547 ID* Maximum Harmonic Current Distortion in % of Load Demand Current Voltages 0.1-69-kV I SC /I L Harmonic Order (Odd Harmonics) <11 11<h<17 17<h<3 3<h<35 35<h A1 <0* 4 1.5 0.6 0.3 5 A 0<50 7 3.5.5 1 0.5 8 THD
10 Even Harmonic Was not a controlling factor back when the standard was created IEEE Std 519 & 1547 Even harmonics = 5% Odd harmonics Authors recommendation (Even = Odd) Even harmonics = 100% Odd harmonics PV has even harmonics that comparable to the odd harmonic
11 II. Modeling and simulation Circuit model: Mile 1.47 kv CKT 10 MVA substation transformer 4 MVAR Cap Bank 500 kw PV units (total: ~ 5 MW) Harmonic source PV unit#1 Sunlight DC AC PV unit# PV unit#3 Background Harmonics Load 480 V Bus PV unit#4 Utility mile 500 MCM Cable 69 kv Bus Substation Transformer 69/1.47 kv 1.47 kv Bus Additional PV units... 4 MVAR Cap Bank 10 mile 336 Al Overhead Line Lumped Load: 3 MVA, 0.9 p.f. Filter
1 Harmonics from renewable Energies - below 9 th harmonic order - both even and odd harmonics TYPE-I, THD = 3% TYPE-II, THD = 6% Background harmonics: - from TV, computer, fluorescent lamps, etc - harmonic orders: 1, 3, 5, 7, 9
13 Study Cases Case Case 1 Case 3 Heavy load Capacitor on PV on/off Case 4 Case 1 Light Load and Capacitors off Photovoltaic Power Heavy Load and Capacitors on Light Load 1 4 8 1 4 8 1 AM PM AM System Loading Time Profile
14 III. Analysis, results and discussions Research approach: Resonance Point THD Compare Harmonic Limit Decide standards PV Penetration level 1 3 5 7 9 11 13 15 Harmonic order
15 Capacitor and Resonance Point Bus Scan Impedance Magnitude (pu) 700 600 500 400 300 00 100 0 4 MVAR MVAR 1 MVAR 0 MVAR 0 5 10 15 0 5 30 35 40 45 50 Harmonic Order Impedance Scan at the 1.47 kv Bus
Voltage Distortion (%) 16 Voltage Distortion Percentage Voltage Distortion at the 1.47 kv Bus 4 MVAR Capacitor at 1.47 kv Bus with 4 MVAR Capacitor in Service 5 Limit: 5 MW TYPE I 4 3 1 0 IEEE criteria Limit: 1. MW TYPE II TYPE-I THD TYPE-II THD 1 3 4 5 6 PV (MW)
Current Dis IEEE-1547 modified 17 4.0 Violations.0 Current 0.0 Distortion Percentage (Type-II harmonics) 1 3 5 7 9 11 13 15 17 19 1 3 5 7 9 Harmonics at 480 V Cable with 4 MVAR Capacitor in Service Current Distortion (%) 8.0 IEEE-519 1.6 MW 6.0 1.8 MW IEEE-519 modified.0 MW 4.0 IEEE-1547 modified Violations.0 0.0 1 3 5 7 9 11 13 15 17 19 1 3 5 7 9 Harmonics
18 PV penetration limit summary Type-I Harmonics w/o background harmonics w/ background harmonics Type-II Harmonics w/o background harmonics w/ background harmonics 1.47 kv Bus 5.0 MW 3.0 MW 1. MW 0.8 MW IEEE-519 > 5.0 MW > 5.0 MW 0.6 MW 0.6 MW 480 V Cable IEEE-519 modified > 5.0 MW > 5.0 MW 1.6 MW >.0 MW IEEE-1547 modified > 5.0 MW > 5.0 MW 1.0 MW 1.0 MW
19 Mitigation: Harmonic filters Bus Scan Impedance Magnitude (pu) 80 70 60 50 40 30 0 10 without filters With filters Substation Transformer Notch Filter Tune at the 5 th Order Harmonics High-Pass Filter Tune at the 7 th Order Harmonics Utility 69 kv Bus 1.47 kv Bus 4 MVAR Capacitor bank. Operation mode: 1,, and 4 MVAR To Distribution Circuit 0 0 5 10 15 0 5 30 35 40 45 50 Harmonic Order Dirty Water Dirty power FILTER Clean Water Clean power
0 IV. Conclusions The maximum PV penetration can be significantly influenced by: criteria adopted capacitor operating modes harmonics injected from PV units Harmonic filters could be used to increase PV penetration