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Interconnecting to the grid. A bird’s eye view. Here kitty kitty. Can I please connect to your grid?. Cost recovery. Safety. Unfair to rate payers. Power Quality. Fault Detection. Liability. Blah Blah Blah. But it’s good for you!!!. T&D deferral Reduce peak Improved reliability
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Interconnecting to the grid A bird’s eye view
Can I please connect to your grid? Cost recovery Safety Unfair to rate payers Power Quality Fault Detection Liability Blah Blah Blah
But it’s good for you!!! • T&D deferral • Reduce peak • Improved reliability • Voltage support • Yada, Yada, Yada
History • First power plants were CHP • Grids were served by local plant • Regulated Utilities consolidated • PURPA 1978 • EPACT 2005 Source: IEEE Source: IEEE
5000 1930s 4000 1950s $/kW Average Installed Cost 3000 1970s 2000 1980s 1000 1990s 0 0 200 400 600 800 1000 1200 Plant Power Capacity (MW) Bigger is Better? Source: ACEEE
Hey, what happened to my energy? Source: ACEEE
Why do I have to study history? Source: Casten, T. & Casten, S. “Transforming Electricity”
Jargon • Cogen • CHP • BCHP • CCHP • RE • TE • DG • DE • DR • DER • DP • DRP
Types of Operation • Grid Isolated • Export • Import • Buy All/Sell All • Synchronous • Inductive • Inverter
Grid Isolated PCC Switch Open No Power Flow Loads Loads
Import Switch Closed Power Flow PCC Loads Loads
Export Switch Closed Power Flow PCC Loads Loads
Buy All/Sell All Switch Closed Power Flow PCC Switch Closed Power Flow Loads Loads
Technical Issues(lots of math but solutions are possible) • Anti-Islanding • Grid Protection • Generator Protection
Anti-islanding Substation X Feeder Breaker
Anti-islanding • Over/Under Frequency – [81o/u] • Overvoltage – [59] • Undervoltage – [27] Good for DG < 15% of feeder load ~15,000 small DG with no reported injuries1 1IREC
Anti-islanding • Reverse Power - [32] • Directional Over-Current - [67] • Instantaneous Over-voltage - [59I] • Trip Transfer
Grid Protection • Fault Current Contribution • Power Flow • Ground Fault (Transformer Selection) • Over voltage damage to Grid Equipment • Ferroresonance • Power Quality Issues
Generator Protection • Synch Check - [25] • Negative Phase sequence - [46 / 47] • Loss of Excitation - [40] • Circulating Currents
Switchgear Digital Multifunction Relay PLC /Microprocessor Communications Technologies
Regulatory / Business Issues(hardly any math but solution almost impossible) • Standards • Rates • Permitting • Obligation to serve • Liability • Incentives
Standards – We don’t need no stinking standards • IREC Model Interconnection Standards • IEEE 1547 • PJM • FERC • Texas • California Rule 21
Interconnect Standards for DG in effect under development (May 2007)
Consideration of EPACT 2005 Interconnect Standard X X X X X X X X X X X X X X X rejected X under consideration X adopted (May 2007)
Rates • Avoided Cost • Back Stand Charge • Exit Fee • Additional Facilities Charge • Curtailable • Net Metering • RTP
Net metering www.dsireusa.orgMay 2007 NH: 25 MA: 60 RI: 25 * CT: 100 100 VT: 15/150 100 * * 50 100 * 40 * 25 30 * 10/400 20 * 25/100 * 25 * * no limit 500 * PA: 50/1,000/2,000 NJ: 2,000 DE: 25 MD: 2,000 DC: 100 VA: 10/500 * 40 * 150 * * * 25 2,000 10 * 25 * 1,000 15 * 20/100 * * 100 25/300 10 10/100 80,000 * 50 25/100 50 varies Net metering is available in 41 states + D.C. State-wide net metering for all utility types * State-wide net metering for certain utility types (e.g., IOUs only) Net metering offered by one or more individual utilities (Numbers indicate system size limit in kW; in some cases limits are different for residential and commercial systems, as shown)
Consideration of EPACT 2005 Net Metering X X X X X X X X X X X X X X X X rejected X under consideration X adopted (May 2007)
So what am I supposed to do? • Define your project • Generation information • Transformer type • Protection scheme • Operational characteristics • Understand your benefits (think out of the box) • Rates impacts • Incentives • Reliability / Productivity
So what am I supposed to do? • Understand the rules • PURPA • Utility interconnection rule set • PUC • Permitting – Air, Siting, NEC, Water, etc. • Understand the process • Talk to your Utility (a lot – be a “nice” pest) • Talk to others who have done a project • Talk to “experts”
Where else to get help • www.eere.energy.gov/de/chp/chp_applications/information_resources.html • www.epa.gov/chp/ • www.dsireusa.org • www.irecusa.org • www.uschpa.org • www.districtenergy.org
Contact Info Keith McAllister, PE Co-Director CHPCenterSE NC Solar Center NC State University 919-515-3933 keith_mcallister@ncsu.edu