1 HARMONIC ANALYSIS OF SELECTED DG DEVICES Pradipta Kumar Tripathy, Durgesh P. Manjure, Dr. Elham B. Makram CLEMSON UNIVERSITY ELECTRIC POWER RESEARCH ASSOCIATION Clemson University, Clemson, SC Power System 2002 Conference: Impact of Distributed Generation March 13-15, 2002 Clemson, SC

2 Clemson University Electric Power Research Association  Introduction  Background  Modeling  Results  Conclusion & Future Work OUTLINE

3 Clemson University Electric Power Research Association INTRODUCTION Objective To study the effect of Distributed Generation on distribution systems with respect to harmonic distortion. Outline of Research  Literature review  Case studies on the impact of different types of DG in residential, commercial, and industrial systems to the distribution system Methods Used  Time domain method for simulation

4 Clemson University Electric Power Research Association Harmonic Sources in Power Systems  Saturable devices  Nonlinear loads  Power electronic devices Harmonics in typical DG systems  Microturbines  Wind Turbines  Photovoltaics BACKGROUND

5 Clemson University Electric Power Research Association A TYPICAL RESIDENTIAL PV SYSTEM

6 Circuit components used for modeling the PV system are  A constant voltage DC source  A single phase inverter  An isolating transformer  A single-tuned filter Clemson University Electric Power Research Association MODELING OF PV SYSTEM

7 Clemson University Electric Power Research Association MODELING OF RESIDENTIAL SYSTEM Residential system is modeled by considering four typical houses. Loads considered in each house: Linear Loads (assumed)  Incandescent light  Refrigerator load Nonlinear Loads  Compact Fluorescent Light  Television Load  Heat pump

8 Case 1: Harmonic distortion in the presence of DG as a standalone unit supplying residential loads Case 2: Harmonic distortion in the distribution system due to residential system loads alone Case 3: Combined effect of residential loads and DG on distribution system harmonics Clemson University Electric Power Research Association CASES STUDIED

9 Clemson University Electric Power Research Association TEST SYSTEM USED FOR CASE 1

10 Clemson University Electric Power Research Association RESULTS FOR CASE 1

11 Clemson University Electric Power Research Association TEST SYSTEM USED FOR CASES 2 & kV/4.16 kV 4.16 kV/0.208 kV PV System kV Residential loads Substation Three phase loads Single phase loads House1 House2 House3House4 Load current Load voltage Primary current Primary voltage Line reactor Isolation transformer kV/4.16 kV 4.16 kV/0.208 kV PV System kV Residential loads Substation Single phase loads House1 House2 House3House4 Load current Load voltage Primary current Primary voltage Line reactor Isolation transformer

12 Clemson University Electric Power Research Association RESULTS FOR CASES 2 & 3 Comparison of load voltage Comparison of load current

13 Clemson University Electric Power Research Association RESULTS FOR CASE 2 & 3 Comparison of primary voltage Magnitude (%) Comparison of primary current

14 Clemson University Electric Power Research Association THD(%)Residential system fed by distribution system Residential system fed by distribution system and PV system Load current Load voltage Primary current Primary voltage RESULTS FOR CASE 2 & 3 Comparison of THD

15 Clemson University Electric Power Research Association CONCLUSIONS  Harmonics produced on the load side by the PV system were not significant compared to the high current distortion caused due to the household nonlinear loads.  Harmonic distortion injected to the distribution system decreased after connecting the PV system due to harmonic phasor cancellation.  Results presented are for the specific scenario discussed, and could change with varying nonlinear loads and/or varying DG types and sizes

16 FUTURE WORK  Impact of varying levels of DG penetration on harmonic propagation, in the presence of nonlinear loads  Modeling of other types of DG  Effect of DG on harmonic distortion in case of commercial and industrial systems  Combined effect of PV and microturbine system Clemson University Electric Power Research Association