H&M Power Conversion Segmented Inverter 2010 R1
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The document discusses a proposed modular power conversion system for wind turbines to improve reliability and availability. It notes that lost revenue from non-operating turbines increases energy costs at large wind farms. The proposed system uses independent and redundant power modules to maximize uptime even if one module fails. Analysis shows that for a 30MW wind farm experiencing typical failure rates, the system could save over $165,000 per year by preventing lost energy capture from turbine downtime. With multiple annual failures averted over the farm's 20-year lifespan, the financial benefits outweigh the additional $42,000 cost per turbine for the modular system.
H&M Power Conversion Segmented Inverter 2010 R1
- 1. 01/29/15 1 690 V Grid PM Generator 690V 690VAC, 460 Amps ~ = = ~ ~ = = ~ ~ = = ~ 3 Phase 2.5MW 690 V By: Dr. Sammy Germany
- 2. 01/29/15 2 Background: To achieve low cost of energy, turbine manufacturers have traditionally focused on: • Component cost • Component reliability • Variable speed applications to capture more low wind speed energy More recent industry trends have focused on • PMG - energy capture in wider wind speed range • High efficiency & Reducing O&M costs • Designs for lower class sites (Class 3) Power System Focus – Availability + Uptime • Uptime is the key to capture more energy • Diminishing returns for power component MTBF power component MTTR Uptime kWh Energy: Power & Time
- 3. 01/29/15 3 Modular Multi-MW Converters High Reliability – High Availability 1. Designs are built to be reliable, tough inverters 2. Mechanical robustness to reduce O&M costs in harsh turbine environments 3. Modularity: Operational redundancy, increasing availability of system even under fault conditions Capacity 100% Failure event MTTR Without redundancy With redundancy time Energy Savings w/ redundancy
- 4. 01/29/15 4 Class 4 - 30 MW Wind Farm Met Data 0 2 4 6 8 10 12 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month WindSpeedm/s) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 PerUnitTurbinePower(MW) Wind Speed (m/s) Average Power • Class 3-4 Wind farm met data used for energy harvesting case studies • Peak hourly wind speed average 80% - Optimal for parallel units. • 10 Towers, 3MW turbines Turbine Power Month
- 5. 01/29/15 5 What is the problem? Lost revenue from non-operation turbines increased the cost of energy in large wind farms. • Turbine repairs occur after multiple turbines have failed (high O&M costs) • In large farms, 3-5 turbines may need to be down before serviced (up to 3 months) • Long MTTR of wind turbines impacts energy capture rates. How significant is it for a 30MW Wind Farm? • $6.6M : Yearly energy revenue for a Class 4, 30MW wind farm (6.5 c/kW.hr) • $330k (5%): Yearly lost revenue from 3 turbine failures with 3 months downtime. Benefits of a DRS Power System Solution: • If one (1) turbine failure is due to an inverter, the module remains operating and capturing energy. • $165k Savings: 2.5% of wind farm’s yearly revenue NPV: $0.8M – 1.8M for 1 to 2 power failures / yr over life of wind farm (20yrs) (Considering increased energy generated due to uptime and the cost of power system modularity)
- 6. 01/29/15 6 690 V Grid PM Generator 690V 690VAC, 460 Amps ~ = = ~ ~ = = ~ ~ = = ~ 3 Phase 2.5MW 690 V Topology Description • 500kW 690V full conversion power modules • Independent dc bus per converter stage to maximize availability • Isolating grid and generator contactors • Integrated dynamic brake for LVRT • Suitable for medium speed and direct drive. • Optional generator dv/dt filters Inherent Redundancy to maximize availability Controls • Independent power module control electronics. • No master controller with a single point of failure. Benefits + Lower bearing current stress + Open winding failure on generator + Hatchable converter for low MTTR
- 7. 01/29/15 7 DC Bus Intertie Inverters A common approach used by commercial motor drive suppliers - No ability to isolate inverters from the shared dc bus reduces availability. + Lower Cost inverter controls, switchgear, filters, power module ratings ($42k delta) Investment Project Financial Analysis Date: Unit: DRS-PCT Project Name: 2.5 MW Wind Converter Investment Plan 1 2 3 4 5 6 7 8 Components $420,000 $0 $0 $0 $0 $0 $0 $0 Total investment $420,000 $0 $0 $0 $0 $0 $0 $0 Revenue $0 $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 Income $0 $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 ROS % 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% Net Cash Flow ($420,000) $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 $330,000 Cost of Capital 12.0% NPV $1,795,273.54 20 yrs IRR 76% 7 yrs 30MW Wind Farm Benefit with a DRS Power System Net Present Value of Investment in Modularity. $0.8M – $1.8M: (1 to 2 failures / yr over 20 yrs) Investment: $42k per turbine $420k per wind farm. Revenue: $165k per inverter event / yr
- 8. 01/29/15 8
- 10. 01/29/15 10 Full Power Conversion Systems for Wind Applications • Power Module and cabinet system under development • Power modules: Grid & generator side inverters Filters, protection, dynamic brake, controls, communications. • Generator Compatibility: PM, Synch., DFIG • Available: 500kW system in 2010 Major Specifications Utility Voltage: 690V Output Capacity: 600kVA, 500kW Grid Freq: 50Hz or 60Hz Generator Freq. 10Hz to >150Hz depending on generator requirements Cooling : Air or liquid cooled Location: Up-tower or down-tower
- 11. 01/29/15 11 General Description • 500kW, 690V grid connection • PM or synchronous generators compatibility • 1700V IGBT power converter • Integrated dynamic brake for Low voltage ride through • Liquid cooled power converter • Grid contactors for protection and isolation. Generator isolation optional • IP54 Air cooled cabinet • High reliability power module design: high MTBF: Film capacitors, low IGBT thermal stress, liquid cooling.
- 12. 01/29/15 12 DC bus capacitors IGBTs Gate drivers Module Design under development Control board Bus plane
- 13. 01/29/15 13 Wind Farm Power (MW) 30 MW Number of Turbines 10 Number of failures per month 1 Duration (months) 3 Lost turbine months 6 Total turbine months/ yr 120 % of lost turbine months 5% Savings - if 1st turbine failure is eliminated # turbine months saved 3 % turbine months saved 2.5% Event Description • one turbine failure per month • Service occurs after 3 months, 3 failures • 1st failure is assumed to be the inverter – and mitigated. • Savings shown.
Editor's Notes
- #6: Based on DOE graph – 110B kW*hrs in 2011, 20% of that power lost in UPS / Power supply, $0.1/kW*hr rate charge\