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Drives and Pump Optimization

Drives and Pump Optimization. Discussion on Pump Optimization Principles and “Need to Know” Drive Technology . Presented by Paul Krasko. Smart Water for Smart Cities Workshop 11:00am Tuesday May 20, 2014. Water Wastewater (WWW) Challenges: Energy Usage. Reduced financial resources

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Drives and Pump Optimization

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  1. Drives and Pump Optimization Discussion on Pump Optimization Principles and “Need to Know” Drive Technology Presented by Paul Krasko Smart Water for Smart Cities Workshop 11:00am Tuesday May 20, 2014

  2. Water Wastewater (WWW) Challenges: Energy Usage Reduced financialresources Energy efficiency awareness Energyuse • Demandfor WWW • Ageof infrastructure • Legislativecompliance Process = 70% Pumping = 16%

  3. Finnish Technical Research Center Report: “Expert systems for diagnosis of the condition and performance of centrifugal pumps” • Average pumping efficiency is below 40% • Over 10% of pumps run below 10% efficiency • Major factors affecting pump efficiency • Throttled control valves • Pump over-sizing • Seal leakage causes highest downtime and cost Evaluation of 1690 pumps at 20 process plants:

  4. System Curve UncertaintyResults in Uncertain Pump Operation - and higher costs

  5. Pumps System Overview and Fundamentals

  6. Overview The pumping system: End-use Components • Pumps • Motors, engines • Piping • Valves and fittings • Controls and instruments • Heat exchangers • Tanks • Others • Water treatment • Wastewater treatment • Water distribution • Power generation • Irrigation

  7. Overview, continued System Approach Componentoptimization involves segregating components and analyzing in isolation System optimization involves studying how the group functions as one as well as how changing one component can help the efficiency of another Electric utility feeder Transformer Motor breaker/starter Adjustable speed drive (electrical) Motor Coupling Pump Fluid System Served Process(es)

  8. Pump Fundamentals There are two basic types of pumps:

  9. Pump Fundamentals, continued Impart energy to the liquid by increasing its speed in the impeller and then converting the speed to pressure through diffusion in the volute. Centrifugal Pumps

  10. AC Motors - Variable Torque Applications Variable Torque (VT) 100 % Torque, Flow, & HP (Amps) Torque 50 Flow HP % Speed 50 100 (Base)

  11. Impart energy by applying mechanical force directly to the liquid through a collapsing volume Pump Fundamentals, continued PD Pumps

  12. Energy Efficiency in Pumps • Load Characteristics The Main Target ( first priority) The Next Step ( second priority)

  13. Pump Head Pressure Static head is the energy needed to overcome an elevation or pressure difference between the suction and discharge vessels. Frictional head loss increases by the square of the velocity change of the liquid in the pipe. In most cases:

  14. Pump Head Pressure Friction Head Static Head System Head Curve produced by US DOE PSAT Software

  15. Friction Head May occur in pump systems due to hydraulic losses in: Piping Valves Fittings (e.g., elbows, tees) Equipment (e.g., heat exchangers) Which are used to control flow or pressure by: Automated flow and pressure control valves Orifices Manual throttling valves Pump Head Pressure

  16. Variable frequency drive (vfd) benefits with Pumps

  17. Energy Efficiency in Pumping Systems • Motor costs

  18. Energy Efficiency in Pumps • Energy wastes How your money is wasted! Car example : …try to regulate the speed of your car • keeping one foot on the accelerator • the other on the brake. Pump example : … try to adjust the pump output • running the motor at full speed • control the flow with a throttle valve Still one of the most common control methods in industry ….. with a considerable waste of energy

  19. VFD Benefits with Pumps • Physical laws for centrifugal loads It’s pure physics:Due to the laws that govern centrifugal pumps, the flow of water decreases directly with pump speed Affinity laws of centrifugal loads: Flow = f (motor speed) Pressure = f (motor speed)2 Power = f (motor speed)3

  20. VFD Benefits with Pumps • Physical laws for centrifugal loads A motor running at 80% of full speed requires 51% of the electricity of a motor running at full speed.

  21. VFD Benefits with Pumps • Physical laws for centrifugal loads A motor running at 50% of full speed requires 12.5% of the electricity of a motor running at full speed.

  22. VFD Benefits with Pumps • Physical laws for centrifugal loads • A small reduction in speed produces a significant reduction in power • Relevant applications : Pumps • The resisting torque of centrifugal pumps varies with the square of the speed : T = kN² • Power is a cubed function P = kN³ EX 50HP 10Hrs/day, 250 days @$.08 With 15% average speed reduction ATL = $7,460 VFD = $4,188 Savings = $3,272 Today, less than 10% of these motors are controlled with variable speed drives

  23. Efficiency of pumping systems

  24. VFD Benefits with Pumps Other Benefits In addition to energy savings, using a VFD has many other advantages: • Less mechanical stress on motor and system • Less mechanical devices - Less maintenance • Process regulation with PID regulators, load management functions • Reduce noise, resonance avoidance • Performance and flexibility, range settings, above base operations • Easier installation and settings, drive mechanics • Can be controlled with automation, communication networks

  25. Steps to obtain pump optimization

  26. Pump Optimization Complete a detailed Pump Assessment Pumps are usually consuming more energy than necessary: • The pump is oversized and has to be throttled to deliver the right amount of flow. Energy is lost in the valve. • Pumps that are not running close to their best efficiency points (BEP) operate at lower efficiency. Throttled pumps usually fall into this category. • Pumps are running with by-pass, or recirculation, lines open. • Pumps are running although they could be turned off. • The pump is worn and the efficiency has deteriorated. • The pump/system was installed or designed incorrectly (piping, base plate etc.)

  27. Pump Optimization Complete a detailed Pump Assessment To determine whether these reasons apply, some basic information is needed: • Actual system demand (flow and pressure) • Operational flow rate as a function of time (the duration curve) • Flow controls • The pump curve • Where the pump operates on the curve

  28. Process Energy Optimization Automation is the key • Develop consistent and appropriate milestone and deliverable expectations • Standardize program schedule tracking requirements • Establish key energy management performance metrics • Produce meaningful reports that allow for clear and concise decision-making • Install additional monitoring equipment as needed

  29. Considerations for Variable frequency drives for water and wastewater

  30. VFD Topics • Type(s) • Enclosure/Environment/Packaging • Harmonics/Harmonic Mitigation IEEE 519 • Accessibility • Sustainability Data Bulletin 8800DB1302

  31. VFD Considerations • The industry has standardized on PWM 6 pulse drives. • Where 6 pulse refers to the front end of the drive and a bridge of 6 diodes converting incoming AC to DC power. • A DC bus (capacitor) • Insulated Gate Bipolar Transistors (IGBT) as the output components • The output of which generates a simulated RMS waveform with a constant V/Hz ratio

  32. One of These…

  33. Packaging… NEMA UL Type 1/12 MCC Enclosed Altivar Plus

  34. Harmonics Mitigation • This continues to be a big topic in Water and Wastewater • The motor loads on VFDs are a large percentage of the total load. • Many consultants have standardized on designs by HP requiring line reactors or multipulse drives (typically 18 pulse). • There are multiple solutions • One size does not fit all. • Schneider Electric offers as standard…18 pulse VFD, Passive Harmonic Filter and Active Harmonic Mitigation

  35. Harmonics Reduction Typical AC drive 100HP • Typical 6 pulse AC drive • without line reactor • Input voltage: orange • Input current: cyan • Large current spikes due to capacitors charging • Peak currents = 300 amps • Harmonic current distortion • Large double humped current waveform significantly contributes to harmonic content. Total Harmonic Distortion Current THDI = 80%

  36. Harmonics Reduction AC drive with 3% line reactor 100HP • Typical 6 pulse AC drive • With 3% line reactor • Input voltage: orange • Input current: cyan • Lower current spikes due to capacitors charging • Peak currents = 190 amps • Harmonic current distortion • Significant double humped current waveform reduced • Total Harmonic Distortion Current • THDI = 38%

  37. 18 Pulse Drive Using the Same 6 Pulse Inverter… STD 6 Pulse Inverter 18 pulse Diode Bridge Line Reactor Phase Shifting XFMR

  38. 18-Pulse Power Converter Configuration DC Bus connections to Altivar 61/71 Drive

  39. 18-Pulse Drives: What You Get 6-Pulse power converter (no line reactor) 18-Pulse power converter Clean power performance

  40. Passive Harmonic Filter Drive Using the Same 6 Pulse Inverter… STD 6 Pulse Drive Passive Harmonic Filter

  41. Passive Harmonic Filter Drive • Passive Harmonic Filter Mitigation provides as good or better than 18 pulse. • Better mitigation given voltage imbalance • Footprint of drive is typically smaller than 18 pulse. • Efficiency of drive is better than 18 pulse • Losses of 18 pulse bridge + Transformer + Line Reactor > Passive Harmonic Filter • Cost is typically lower than 18 pulse • Output to the motor is identical. What’s not to like?

  42. Results

  43. Results

  44. Accusine Used with One or Many 6 Pulse Drives…

  45. The Variable Frequency Drive for WWW The Altivar ® 61 is our standard 6 pulse inverter for variable speed applications used in centrifugal pump and fan / blower applications offering the highest levelof features,functions,and flexibility.This same inverter is the heart of our configured enclosed applications, 18 Pulse Drives, Motor Control Centers and our new Passive Filter Packages. All the Inverter parts, programming, troubleshooting, wiring, interfacing, etc. is common.

  46. Drives System Center Product Offering Altivar 61/71 Plus Designed for rugged municipal process environments. Custom options to serve a wide range of applications. • Growing sectors requiring high horsepower drives • NEMA Type 12 enclosure • Altivar 71 • 125-700hp, 460VAC • 125-700hp, 600VAC • Altivar 61 • 125-900hp, 460VAC • 125-800hp, 600VAC

  47. Drives System Center Product Offering Altivar 61/71 Plus • Altivar 71 • 700-1800hp, 460VAC • 700-2100hp, 600VAC • Altivar 61 • 900-2000hp, 460VAC • 800-2500hp, 600VAC • Altivar 71 • 125-700hp, 460VAC • 125-700hp, 600VAC • Altivar 61 • 125-900hp, 460VAC • 125-800hp, 600VAC

  48. Drives System Center Product Offering • Variable Torque • 125-900hp, 460VAC • 125-800hp, 600VAC • Constant Torque • 125-700hp, 460VAC • 125-700hp, 600VAC Top mount ventilation Schneider Electric Enclosure Control transformer Flexibility for control requirements with swiveling control panel Altivar power converter Easy maintenance – power converter mounted on rail system Fused disconnect Motor connection Line contactor (optional) DV/DT motor filter (optional) Bottom entry Standard 4” plinth (8” optional) for bottom entry

  49. Other Drive/System Application Considerations • Enclosed drive or packaged drive short circuit current rating • SE = 100k amps as standard • Power loss ride through – especially for pump stations • SE meets Semi F47 standards • Communication capabilities • SE offers Modbus Serial and 11 additional Protocols as options. • Built in web server and diagnostic web displays with Ethernet. • Built in Bluetooth interface capability

  50. Considerations for total cost of ownership (TCO) of your next pumping system

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