Coincident Peak Billing Demand Savings using Conservation Voltage Reduction

Transcription

1 Coincident Peak Billing Demand Savings using Conservation Rob Ardis, PE COO, Pee Dee Electric Cooperative

2 CVR versus VVO Volt-VAR Optimization main purpose is to reduce generation and fuel requirements by reducing system losses on a large scale 1. Use voltage regulation to start at a lower (compared to tradition) voltage and maintain that level. This reduces kwh and kvarh delivery. 2. Use capacitors to further reduce kvarh delivery requirements. 3. This combination (1 and 2) reduces current in system conductors and, therefore, reduces system losses. 4. Also happens to reduce demand when system is peaking. We use CVR to improve our billing load factor. 1. Starting voltage is set at 126V so that voltage at end of line is still tolerable without regulation (normally). Reduces maintenance costs and system weak points. 2. Reduce this voltage at times of likely peaks to lower demand charges.

3 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

4 Demand Charge History

5 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

6 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, SC 6-person team (SCADA from Home) Very few capacitors in system Tilt: Shift from negative to positive

7 Historical Peak Hours

8 5500 System Load versus Florence Temperature

9 Day of the Peak

10 Hour of the Peak

11 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

12 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.

13 Typical Winter Morning :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

14 September 8 (3:43-8:00) Real Reactive :00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00

15 September 12 (5:44-7:50) Real Reactive :00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00

16 September 28 (3:33-7:11) Real Reactive :00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00

17 Sample Month Net Savings Estimated Demand Reduced: kw Percent : 2.59% Profit per kwh: 5.3 mills Cost of control per hour: $ Savings during peak: $37,884 Time we were in control: 21 hours Net Savings: $34,412 Last Year: $400k-$500k

18 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

19 What s New? Automating the process with converted water heater switches Our newest AMR meters return voltage readings (5257 current count). Two peaks now production and transmission New daily report from our G&T Using CVR to Reduce Peak Load

20 Using CVR to Reduce Peak Load

21 Questions??? Contact Information: Rob Ardis (843)