How to Use Your Existing SCADA for Energy Management

Don Best, HDR Engineering, Inc.

Presentation Outline

• Energy Management• Connect a Power Meter to SCADA• Understand Your Electric Bill• Energy Benchmark Studies• SCADA for Energy Conservation

Energy Management

• Process of monitoring, controlling, and conserving energy:– Metering your energy use and collecting the data– Finding opportunities to save energy

• Energy Conservation Measures (ECM’s)• Perform an Energy Audit

– Taking action to target the opportunities• Start with the “energy hogs”

– Tracking your progress

Energy Management

• Benefits of using SCADA for Energy Management:– Tracking and trending– Baseline energy use calculations– Information accessible to operators

Energy Management

• Energy Costs are a large portion of the O&M costs of a typical WWTP facility:

• Staffing 46%• Energy 28%• Solids 12%• Others 07%• Chemicals 04%• Maintenance 03%

Power Monitoring

Digital Power Meter (Eaton IQ Analyzer)

Power Monitoring

• Digital Power Meter Parameters: Line CurrentsL-L and L-N VoltagesPower (Watts)Energy Use (Watt-hours)VA and VARsPower Factor Demand (Watts, VA, VARs, Currents)Frequency (Hz)Total Harmonic Distortion (%THD)

Power Monitoring

• Power Meter to PLC/SCADA:– Analog Signals (4-20ma)– Pulsed Output Signal (one pulse per kWh)– Digital Communications:

• Serial: Modbus, Profibus, DeviceNet• Ethernet: Modbus TCP/IP, Ethernet/IP

Power Monitoring

Power MonitoringkW

7-Day Period

Power Monitoring

• Calculate daily, weekly, monthly energy use• Calculate “Unit Energy Consumption”

kWh/MGEnergy used per million

gallons of wastewater treated.

Electric Costs

• Electric Utility Bill:– Energy Use Charges (kWh)– Demand Charges (kW)

• Transmission (monthly demand)• Distribution (monthly demand)• Distribution Facilities Capacity (facility demand)

Electric Costs

• Portland General Electric:– Monthly Demand:

• Is based on the highest power requirement, averaged over any half-hour period during the billing cycle, measured in kW.

– Facility Capacity:• The average of the two highest monthly demand kW for

the last 12 months.

Electric Costs

• City of Newberg, OR WWTP– Oxidation Ditch-Type, Activated Sludge (1987)– Capacity: 4 MGD dry / 20 MGD peak– April 2010 Data:

• Total kWh: 316,604• Total Flow: 131 MG• 2,417 kWh/MG

(Unit Energy Consumption)

Electric Costs

• City of Newberg, OR WWTP– April 2010 Portland General Electric Bill

Energy Use (kWh): $20,145Transmission Charge: $506Distribution Charge: $1,426Distribution Facility Charge: $1,580Others: $1,740Total Charges: $25,397

} Demand Charges(14%)

Energy Benchmark Studies

Compare your plant to energy benchmark studies:

Energy Benchmark Studies

• Each wastewater plant is different:– Plant flow/loading requirements– Treatment level requirements– Type of treatment

• Trickling Filter, Oxidation Ditch– Type of process equipment

• UV Disinfection, Hypochlorite Generators– Size of plant (economy of scale)

Energy Benchmark Studies

Treatment Type kWh/MG

Trickling Filter 950

Activated Sludge 1,300

Advanced Treatment 1,500

Advanced Treatment with 

Nitrification1,900

Oxidation Ditch 2,900

National Average Energy Use by Treatment Type

Energy Benchmark Studies

PG&E Study of 13 WWTP’s in CA

Wastewater Treatment Plants

Ave

kW

h/M

G

Ave Energy Use:2,243 kWh/MG

45% of Energy Usefor Secondary TreatmentProcess

Energy Benchmark Studies

SCADA for Energy Conservation

• Automated DO Controls:

SCADA for Energy Conservation

• Automated Controls for VFD’s:– PID Loop Control: Flow, Level, Pressure

• Monitor Motor Currents:– or Power to motor

SCADA for Energy Conservation

• Motor Starter with “Smart Overloads”:

Provides Motor Current DataLocated in MCCNetworked (DeviceNet)Offers Better Diagnostic Information

SCADA for Energy Conservation

• Manage Motor Inrush Currents (Demand):– Large Motor Loads:

• Stagger Start– Pump Rotation:

• Stop a pump before starting another.

SCADA for Energy Conservation

• Monitor Lift Station Operations:– Daily Pump Start Counts– Daily Pump Run Times– Average Run Time per Start

Look for Signs of Clogging or Faulty Pumps

SCADA for Energy Conservation

• Fine Tune Pump Controls to Improve Efficiency:– Look for conditions where two pumps

are running together at low speeds.– Give priority to your most

energy efficient pumps.

SCADA for Energy Conservation

• Automate the Plant Water System:– Many systems are still manually controlled– Use local Booster Pumps where high pressure is needed– Use solenoid valves for chemical dilution water

• Monitor Mixing Air Flows:– Grit Chamber, Chlorine Contact Basins

• Anaerobic Digesters:– Mixing, Recirculation, and Sludge Heating

SCADA for Energy Conservation

• Power (kW) Alarm Setpoint

(ALARM)

SCADA for Energy Conservation

• Can Loads be Shifted to Off-Peak Hours?– WAS or Sludge Transfer Pumps– Hypochlorite Generators– Sludge Thickening / Dewatering

Summary

• Use Your SCADA System to Help Plant Staff:– Monitor Energy Use– See Results of Energy Conservation Measures– Look for Faulty/Abnormal Conditions– Optimize the Process Controls– Run a More Efficient Plant

Thank You!

For more information contact…Don Best – HDR Engineeringdon.best@hdrinc.com DRIVE SAFE!!