Peak Shaving Using Conservation Rob Ardis, PE COO, Pee Dee Electric Cooperative,
How We Are Billed 12 individual 60-minute coincident peak demands Everyone on rate is held accountable for their contribution when the system was peaking not necessarily their own peak Calendar Month 20 SC Distribution Cooperatives do not generate
$ per kw Demand Adjusters History and Forecasts 12.000 10.000 8.000 6.000 4.000 10/07 7/08 8/08 9/08 11/08 2.000 0.000 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017-2.000
Voltage Regulation If it wasn t cost effective before, might be now Need to analyze technical and man-power requirements Must also consider tolerable voltage ranges
Specific to PDEC Leaning more toward feeder regulation Very few downline regulators Targets for load control (130 MW) First day of month Temperature in Florence 5-person team (SCADA from Home) Very few capacitors in system
Historical Peak Hours
5500 System Load versus Florence Temperature 5000 4500 4000 3500 3000 2500 10 20 30 40 50 60 70 80 90 100 110
Two Basic Types of Loads Constant Power Loads: Motor Driven motors, AC, heat pumps, etc. Fluorescent Lighting Electronic Devices Decrease voltage => Increase current Constant Impedance Loads: Electric Resistance Heating Water Heaters Incandescent Lighting Some office equipment and small machinery Appliances such as oven/range, clothes dryer Power Reduces with Voltage
Simplified Calculations Constant Power: P = constant, P=IV (reduce voltage by 3%, current must increase by approximately 3%). No demand savings. Constant impedance: Z = constant, P=IV, Z=V/I (reduce voltage by 3%, current must reduce by 3% => Power reduces by almost 6%). Demand reduction = voltage reduction squared.
Typical Winter Morning 140 130 120 110 100 90 80 5:00 AM 5:28 AM 5:57 AM 6:26 AM 6:55 AM 7:24 AM 7:52 AM 8:21 AM 8:50 AM 9:19 AM
September 8 (3:43-8:00) 10000 9000 8000 7000 6000 5000 Real Reactive 4000 3000 2000 1000 0 12:00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00
September 12 (5:44-7:50) 12000 10000 8000 6000 Real Reactive 4000 2000 0 12:00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00
September 28 (3:33-7:11) 10000 9000 8000 7000 6000 5000 Real Reactive 4000 3000 2000 1000 0 12:00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00
Sample Month Net Savings Estimated Demand Reduced: 3119.9 kw Percent : 2.59% Profit per kwh: 5.3 mills Cost of control per hour: $165.35 Savings during peak: $37,884 Time we were in control: 21 hours Net Savings: $34,412
Perhaps Three Load Models Constant Power demand does not vary with voltage Constant Impedance demand varies in proportion with the square of voltage Constant Current demand varies directly in proportion with voltage
CVR Not Just for Saving Peak Shaving to Avoid Building Generation Emergency Feeds, Bypass, etc. Losses Reduction May be used to meet non-renewable reduction requirements
Questions??? Contact Information: Rob Ardis rardis@peedeeelectric.com (843) 292-4341