Outline Outline Characterization of Harmonics in a Utility - PDF document

10/31/2012 Outline Outline Characterization of Harmonics in a Utility Characterization of Harmonics in a Utility Feeder with PV Distributed Generation Feeder with PV Distributed Generation → Background → Motivation → Significance of Study → Objectives → Data Acquisition Christine D. Crites, Rajiv K. Varma, Christine D. Crites, Rajiv K. Varma, → Results of Data Analysis Vinay Sharma, and Bill Milroy Vinay Sharma, and Bill Milroy → Conclusions Background Background Motivation Motivation → Wonderland 32M1 feeder supports two solar PV connections → Solar PVs inject harmonic currents into the system → Two capacitor banks on high-tension side → Potential misoperation, overheating or damage to equipment → Compliance with limits in IEEE Standard 519-1992 → Voltage: Total Harmonic Distortion (THD) → THD < 5% → London Hydro aims to keep THD < 3-4% 1

10/31/2012 Significance of the Study Significance of the Study Objectives Objectives → Harmonic characteristics and severity are not well studied → Real data to this detail is difficult to collect 1) Determine whether this feeder is subject → Tedious and expensive to excessive THD → Requires cooperation of many parties (Hydro One, PVs etc.) 2) Study its characteristic harmonics and → One of extremely few studies in the World that provides real data on the subject of harmonics present in the power system identify any potential concerns This study will reveal all harmonic levels, including ambient This potentially changes the results/accuracy of any past studies! Data Acquisition Data Acquisition Data Acquisition Data Acquisition Required measurements: Points of interest: → Measurements were sampled and recorded at timed → Load (kW) → PV Customer #1 (A) → THD → PV Customer #2 (B) intervals for one week → 1-49 th voltage and current → Wonderland TS B bus which supplies harmonics the 32M1 feeder (C) → Solar PVs disconnected for 24hrs to measure ambient harmonics → Both capacitor banks were disconnected during the C study due to equipment failure A B 2

10/31/2012 Results Results General Trends General Trends Load vs. THD Data examined: 2.8 0.53 2.7 1) General observations 2.6 0.48 2) Current THD levels at PV Customer #2 2.5 Power (kW) 0.43 Power 2.4 THD 3) Current THD levels at PV Customer #1 THD 0.38 2.3 2.2 4) Voltage THD levels at Wonderland TS B bus 0.33 2.1 5) Harmonic Content 0.28 2 10/02/2012 0:00 10/02/2012 12:00 11/02/2012 0:00 11/02/2012 12:00 12/02/2012 0:00 Date & Time Current THD at the Solar PVs Current THD at the Solar PVs Current THD at the Solar PVs Current THD at the Solar PVs PV Customer #2 PV Customer #1 Current Distortion Over a Two-day Period Current Distortion Over a Two-day Period 4,000.0 3,500.0 60.0 3,000.0 50.0 % of Fundamental 2,500.0 % of Fundamental 3rd 40.0 3rd 5th 5th 2,000.0 7th 7th 30.0 9th 9th 1,500.0 11th 11th 20.0 13th 13th 1,000.0 10.0 500.0 0.0 0.0 0:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 February 10, 2012 February 11, 2012 February 10, 2012 February 11, 2012 Time of Day Time of Day 3

10/31/2012 Voltage THD at Wonderland TS Voltage THD at Wonderland TS Voltage THD at Wonderland TS Voltage THD at Wonderland TS THD: PVs Off & PVs On 2.85 Wednesday February 8, 2012 Friday February 10, 2012 PVs off – Ambient Harmonics PVs on 2.75 2.65 % THD Time of Day % THD Time of Day 2.55 2.45 THD (%) Max 2.69 8:50 PM Max 2.73 9:50 PM 2.35 PVs OFF (Wed Feb 8) PVs ON (Fri Feb 10) 2.25 Min 1.91 4:20 AM Min 2.06 5:50 AM 2.15 2.05 1.95 Avg Avg 2.27 ------------------ 2.37 ------------------ 1.85 2:14 4:38 7:02 9:26 11:50 14:14 16:38 19:02 21:26 23:50 Time Harmonic Content Harmonic Content As measured Friday February 10, 2012 @ 5:50 PM → On average, the PVs increase the THD on the feeder by 0.1% Wonderland TS feeder terminal (B bus) → Still significant considering the PVs are such a miniscule Voltage & Current Harmonics 4 part of the system (data includes all odd-# feeders!) 3.5 → Maximum THD recorded over entire week: 2.77% 3 → Almost approaches London Hydro’s 3% limit % of Fundamental 2.5 2 → Resonance with capacitor banks may increase THD even Voltage Current 1.5 further 1 0.5 0 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th 13th 14th 15th 16th 17th 18th 19th Harmonic Order 4

10/31/2012 Conclusions Conclusions Thank You! Thank You! → Characteristic harmonics: 3 rd , 5 th , 7 th and 9 th , and to a lesser extent the 11 th , 13 th and 15 th → Several issues identified for further investigation → PVs contribute approx. 0.1% THD → Max THD was 2.77% - not an immediate concern but cause for further DG capacity studies → Data now available as a resource for the planning, design, and optimization of distribution systems 5