Outline Outline Characterization of Harmonics in a Utility - - PDF document

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Characterization of Harmonics in a Utility Feeder with PV Distributed Generation

Christine D. Crites, Rajiv K. Varma, Vinay Sharma, and Bill Milroy

Characterization of Harmonics in a Utility Feeder with PV Distributed Generation

Christine D. Crites, Rajiv K. Varma, Vinay Sharma, and Bill Milroy

Outline Outline

→ Background → Motivation → Significance of Study → Objectives → Data Acquisition → Results of Data Analysis → Conclusions

Background Background

→ Wonderland 32M1 feeder supports two solar PV connections → Two capacitor banks on high-tension side

→ Solar PVs inject harmonic currents into the system → 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%

Motivation Motivation

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Significance of the Study Significance of the Study

→ Harmonic characteristics and severity are not well studied → Real data to this detail is difficult to collect → Tedious and expensive → Requires cooperation of many parties (Hydro One, PVs etc.) → One of extremely few studies in the World that provides real data

• n the subject of harmonics present in the power system

This study will reveal all harmonic levels, including ambient This potentially changes the results/accuracy of any past studies!

1) Determine whether this feeder is subject to excessive THD 2) Study its characteristic harmonics and identify any potential concerns

Objectives Objectives Data Acquisition Data Acquisition

Required measurements:

→ Load (kW) → THD → 1-49th voltage and current harmonics

Points of interest:

→ PV Customer #1 (A) → PV Customer #2 (B) → Wonderland TS B bus which supplies the 32M1 feeder (C)

C A B

→ Measurements were sampled and recorded at timed intervals for one week → Solar PVs disconnected for 24hrs to measure ambient harmonics → Both capacitor banks were disconnected during the study due to equipment failure

Data Acquisition Data Acquisition

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Results Results

Data examined: 1) General observations 2) Current THD levels at PV Customer #2 3) Current THD levels at PV Customer #1 4) Voltage THD levels at Wonderland TS B bus 5) Harmonic Content

General Trends General Trends

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 0.28 0.33 0.38 0.43 0.48 0.53 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

Power (kW) Date & Time

Load vs. THD

Power THD

THD

Current THD at the Solar PVs Current THD at the Solar PVs

PV Customer #2

0.0 10.0 20.0 30.0 40.0 50.0 60.0 0:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 % of Fundamental Time of Day

Current Distortion Over a Two-day Period

3rd 5th 7th 9th 11th 13th February 10, 2012 February 11, 2012

Current THD at the Solar PVs Current THD at the Solar PVs

PV Customer #1

0.0 500.0 1,000.0 1,500.0 2,000.0 2,500.0 3,000.0 3,500.0 4,000.0 0:00 4:00 8:00 12:00 16:00 20:00 0:00 4:00 8:00 12:00 16:00 20:00 % of Fundamental Time of Day

Current Distortion Over a Two-day Period

3rd 5th 7th 9th 11th 13th February 10, 2012 February 11, 2012

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Voltage THD at Wonderland TS Voltage THD at Wonderland TS

1.85 1.95 2.05 2.15 2.25 2.35 2.45 2.55 2.65 2.75 2.85 2:14 4:38 7:02 9:26 11:50 14:14 16:38 19:02 21:26 23:50 THD (%) Time

THD: PVs Off & PVs On

PVs OFF (Wed Feb 8) PVs ON (Fri Feb 10)

% THD Time of Day Max 2.73 9:50 PM Min 2.06 5:50 AM Avg 2.37

• Friday February 10, 2012

PVs on Wednesday February 8, 2012 PVs off – Ambient Harmonics

% THD Time of Day Max 2.69 8:50 PM Min 1.91 4:20 AM Avg 2.27

• Voltage THD at Wonderland TS

Voltage THD at Wonderland TS

→ On average, the PVs increase the THD on the feeder by 0.1% → Still significant considering the PVs are such a miniscule part of the system (data includes all odd-# feeders!) → Maximum THD recorded over entire week: 2.77% → Almost approaches London Hydro’s 3% limit → Resonance with capacitor banks may increase THD even further

Harmonic Content Harmonic Content

As measured Friday February 10, 2012 @ 5:50 PM

Wonderland TS feeder terminal (B bus)

0.5 1 1.5 2 2.5 3 3.5 4 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th 13th 14th 15th 16th 17th 18th 19th % of Fundamental Harmonic Order

Voltage & Current Harmonics

Voltage Current

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Conclusions Conclusions

→ Characteristic harmonics: 3rd, 5th , 7th and 9th, and to a lesser extent the 11th, 13th and 15th → 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

Thank You! Thank You!