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Small Pv Integration On Distribution Pv America 2011 04 04 2011

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  • 1. Integrating PV on Distribution Forrest Small Director, Energy Practice Navigant April 2011 ENERGY
  • 2. Discussion PointsPoints to discuss today» Distributed PV increasing» Effects of high penetrations of distributed PV» Energy storage and distributed PV©2011 Navigant Consulting, Inc. 1 ENERGY
  • 3. Growing PV Installed BasePV installations are increasing dramatically, and could soon exceedannual wind installations. Annual Renewable Energy Capacity Additions (MW per year) 12,000 10,000 Hydro 8,000 Geothermal 6,000 Landfill Gas Biomass 4,000 Solar 2,000 Wind 0 2010 2011 2012 2013 2014 2015 Forecasts assume: no renewal of existing federal tax credits after their current expiration dates; and no new federal stimulus program is created. Source: Navigant Consulting, Inc., January 2009. Note: Solar includes solar PV and CSP; Biomass includes biomass co-firing.©2011 Navigant Consulting, Inc. 2 ENERGY
  • 4. Solar Ownership by UtilitiesA growing number of utilities want to install distributed solar on alarge scale and put it in ratebase. Utility Programs for Distributed PV: Examples of Filings for Rate Basing Filed February 2010 Filed June 2008 Filed February 2009 3 MW 20MW in 2 years, Proposed 4Q 2008 500MW in 5 years3 Modified to 10 MW 5MW Filed February 2009 120MW in 5 years Filed March 2008 250MW in 5 years, Modified to 500 MW3 Filed November 2007 3.5MW in 5 years2 A Sempra Energy Utility Filed January 2010 Filed May 2008 Filed July 2008 Filed May 2009 80 MW 35MW Program 77MW in 4 years1 1.5 MW Additional Utility Programs; 3rd party or community owned Sacramento Municipal Utility District (1MW) , Portland GeneralNotes: Electric (>2MW), Hawaii Electric Company (16 MW), City of1. SDG&E: 55MW owned by utility Ellensburg (<1 MW), City of St. George (<1 MW)2. ACE: 0.5MW will be utility owned and located on utility facilities.3. PG&E and SCE 50% ownership©2011 Navigant Consulting, Inc. 3 ENERGY
  • 5. Connecting PV on DistributionPV can be connected at three levels in the distribution systemdepending on the location and size of the installation. Distributed PV can by interconnected Substation interconnection assumes that the at three levels PV is physically located close to the substation, and a dedicated electrical connection to the low side bus would be Substation made. PV Primary Distribution interconnection assumes that the PV is connected directly to PV the distribution system, and is not integrated with a customer’s electrical Dedicated system. Distribution Metering Circuits Behind the Meter interconnection assumes PV the PV is integrated with a customer’s Net electrical system, and either net metering or Metering dedicated metering could be employed. “Behind the meter”Each point has a practical limit based on the impact of the PV on thedistribution system.©2011 Navigant Consulting, Inc. 4 ENERGY
  • 6. Challenges of High PV PenetrationIn addition to high cost, T&D concerns, communications, andregulatory challenges have limited the PV deployed. Challenges of High PV Penetration Voltage regulation (D) Transmission and Reverse power flow (D) Distribution Concerns Power fluctuation/frequency regulation (T) Harmonics (D) Lack of communications throughout the distribution system Inverter operating limits (e.g., IEEE 1547) Communications Limited ability to forecast PV resource for capacity planning Non-standard communications protocols Unstructured interconnection standards and ownership Regulatory and control in some states Business Models Lack of rate recovery and PV-“friendly” tariffs©2011 Navigant Consulting, Inc. 5 ENERGY
  • 7. Transmission and Distribution Performance ConcernsPast research had indicated that distribution performance concerns ifPV exceeded certain penetrations. Recommended Limitations on PV Penetration Based On T&D Performance Concerns Recommendation T&D for Maximum PV Performance Description of Impact Penetration on Concerns Circuit Peak Load Adequate voltage regulation may be difficult due to changes in Voltage circuit load and power flow while PV is producing. Also of < 40% Regulation concern is voltage depression after a circuit restoration, when load is restored but PV systems have not come back online. Changes in PV output can cause the power flow on Reverse distribution circuits to vary, and in some high generation/low 5% to 30% Power Flow load cases, the flow could reverse. The variability of PV output due to cloud transients has been Power shown to create power fluctuations, and may be incompatible Fluctuation/ with the ramp rates of some central station generation. This 5% to 30% Frequency variability may require higher levels of system frequency Regulation regulation, increasing the cost of accommodating higher penetrations of PV. Source: Distributed Photovoltaic Systems Design and Technology Requirements, C. Whitaker, J. Newmiller, M. Ropp, and B. Norris, February 2008, and Navigant analysis, 2008.©2011 Navigant Consulting, Inc. 6 ENERGY
  • 8. Power Quality ConcernsAs PV penetration increases, harmonics may become an issue that mustbe evaluated case by case. Effects of Harmonics and Limitations on PV Penetration Study Country Summary of Findings Germany (1) TV loads coupled w/ PV created higher distortion Australia (2) Limit found at ~ 18% penetration Denmark (3) Up to 30%; TV distortion > PV Japan (3) Line-end over-voltages on cluster of 550 houses Australia (3) 665 homes connected with no significant impacts Sources 1. Distributed Energy Resources and Waveform Distortion, Math Bollen, Christine Schwaegerl, and Sebastian Schmitt 2. Harmonic Impact of Residential Type Photovoltaic Inverters on 11kV Distribution System, A.A. Latheef, V.J. Gosbell, & V. Smith 3. The Effects of Harmonics Produced by Grid Connected Photovoltaic Systems on Electrical Networks, Abdulvahid Çelebi & Metin Çolak •In some studies non-linear loads in residences (e.g., televisions) had a greater impact on harmonics than PV inverters. •Distribution circuits with strong sources, shorter length and higher voltages tended to be less susceptible to excessive distortion.©2011 Navigant Consulting, Inc. 7 ENERGY
  • 9. Results From Recent Work » NavigantRecent studies show that distribution voltage stays within systemdesign criteria even with high penetrations of PV… On some circuits PV penetration as high as 30% does not exceed voltage limits 1.040 1.030 1.020 Peak Load PV Bus 1.010 Voltage Low Load PV Bus 1.000 Voltage within +/- 3% Voltage Voltage 0.990 Peak Load Minimum 0.980 Feeder Voltage Low Load Minimum 0.970 Feeder Voltage 0.960 Peak Load Maximum Voltage Drop 0.950 0.940 1% 9% 15% 30% DG Pentration Source: Navigant, Analysis of southwest investor owned utility, November 2010.©2011 Navigant Consulting, Inc. 8 ENERGY
  • 10. Results From Recent Work » Natural Resources Canada… even when the PV is located far from a substation. High PV penetration may not exceed voltage limits, even far from the substation Source: Natural Resources Canada. Integration of Photovoltaic Power Systems in High-Penetration Clusters for Distribution Networks and Mini-Grids, 2009.©2011 Navigant Consulting, Inc. 9 ENERGY
  • 11. Results From Recent Work » NRELMonitoring conducted by NREL showed no adverse conditionsoccurred even in a high penetration solar community. Results with Penetrations of 11-13% • No excessive service or substation voltage due to reverse power flow • Cloud transients did not Source: SunPower adversely affect the distribution system • Anatolia SolarSmartSM Homes • No indication that utility voltage Community, Rancho Cordova, CA transients (capacitor switching) • Highly energy efficient homes with caused PV systems to trip off- integrated PV systems line • 2 kW grid-connected PV systems with remotely monitored inverters Source: National Renewable Energy Laboratory. Impact of SolarSmart Subdivisions on SMUD’s Distribution System, July 2009.©2011 Navigant Consulting, Inc. 10 ENERGY
  • 12. Grid Benefits from PV?Smart Grid could support better integration of distributed resourcesand the utility distribution system, and provide grid benefits. AMI facilitates communications between utility information systems and PV inverters Information Flow Inverter Power Electrical Utility Smart Service AMI Information Control Meter Panel Systems Operator Interface Power Flow Load Utility Energy Storage Circuits DA Distribution (ES) System DA helps manage Demand DR curtails small amounts ES provides input to circuit voltage and Response of customer load for short inverter to compensate for accommodate changing (DR) periods of time (<2 hrs) PV variability (<8 hrs) power flow PV system Smart Grid plus DR and ES Functionality Electrical System Components©2011 Navigant Consulting, Inc. 11 ENERGY
  • 13. RecapRecap» Distributed PV will become a significant energy resource in utility systems.» Distribution effects from high penetrations of PV may not be as significant as once thought.» Smart Grid and integrated PV-storage could provide grid benefits.©2011 Navigant Consulting, Inc. 12 ENERGY
  • 14. KeyCONTACTS Forrest Small Director Burlington, MA (781) 270-8303 Forrest.Small@navigant.com©2010 Navigant Consulting, Inc.©2011 13Confidential and proprietary. Do not distribute or copy. ENERGY