TransformersHansDeKeulenaer

Information about TransformersHansDeKeulenaer

Published on July 17, 2014

Author: sreemrudhu

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Energy Saving Opportunities for Transformers: Energy Saving Opportunities for Transformers Hans De Keulenaer Outokumpu Tara Mines Energy Efficient Motors & Transformers Workshop May 7, 2002 Content: 15-May-02 2 Content Introduction Technical issues & standards Economic equations Ecological equations The business case for high efficiency transformers Conclusion Why transformer efficiency is an issue?: 15-May-02 3 Why transformer efficiency is an issue? All electricity passes through several stages of transformation Savings potential of 22 TWh / year for EU Technology exists Economic potential Many pieces to the sustainable energy puzzle Losses in distribution transformers: 15-May-02 4 Losses in distribution transformers No load loss, or iron loss (Po) Load loss, or copper loss (Pk) DC loss Extra losses eddy current loss in windings stray loss Other losses (ventilation, …) Losses in distribution transformers: 15-May-02 5 No load loss Extra loss Resisitive loss Conventional load loss excl harmonics Extra loss due to harmonics Unloaded Rated load Actual load Actual load (excl harmonics) (incl harmonics) Load loss Losses in distribution transformers Iron loss: 15-May-02 6 Iron loss Occurs 24 hours / day, 365 days / year Example: 1,600 KVA, Po = 2,600 W Annually 2,600 W * 8,760 hrs = 22.8 MWh / yr 30 yrs = 684 MWh Emissions (0.4 kg CO 2 / kWh) = 274 tonnes 5 c / kWh = 34,200 € Historical evolution in the production of magnetic steel: 15-May-02 7 Historical evolution in the production of magnetic steel Evolution of magnetic steel since the introduction of cold-rolled magnetic steel: 15-May-02 8 Evolution of magnetic steel since the introduction of cold-rolled magnetic steel Copper loss: 15-May-02 9 Copper loss Occurs only when transformer is loaded Varies quadratically with the load Example: 1,600 kVA, Pk = 17 kW, 50% loaded Annually 17 kW * 8,760 hrs * 0.5^2 = 37.2 MWh/yr 30 yrs = 1.11 GWh Emissions (0.4 kg CO 2 / kWh) = 444 tonnes 5 c / kWh = 55,500 € Loading: 15-May-02 10 Loading Case 1: 30% of time 80% load 70% of time 10% load Case 2: 8 hours @ 80% 8 hours @ 40% 8 hours @ 10% 30% 20% Typical load profile: 15-May-02 11 Typical load profile Results: 15-May-02 12 Results Energy transformed: 1,600 kVA * 0.5 * 8,760 = 7,008 MWh / year Efficiency  = 7,008 / (7,008 + 22.8 + 37.2) = 99.2% Lifetime cost: Transformer: 10,000 € 10% Iron loss: 34,200 € 35% Copper loss: 55,500 € 55% Total 99,700 € 100% Transformer efficiency: 15-May-02 13 Transformer efficiency 400 kVA, efficiency level A-A’ (HD428) Efficiency @ low load: 15-May-02 14 Efficiency @ low load 400 kVA, efficiency level A-A’ (HD428) Efficiency standards: 15-May-02 15 Efficiency standards Two approaches European approach: specify Po and Pk CENELEC HD428 (oil) Po class A’, B’, C’ Pk class A, B, C (nine combinations) CENELEC HD538 (dry) one class for Po, Pk US approach: specify efficiency at average load (typically 35-50%) Distribution transformer efficiency standards: 15-May-02 16 Source: CENELEC Distribution transformer efficiency standards Extreme cases : 15-May-02 17 Extreme cases High loss >> AA’ Low loss >> CC’ PowerPoint Presentation: 15-May-02 18 Comparison of efficiency at 50% load Conductor materials: 15-May-02 19 Conductor materials Cu and Al transformers can be built to comply to the same performance and quality standard Smaller ratings are typically cheaper with Cu In general, use of Cu leads to: heavier, but more compact windings a smaller core a smaller, more compact transformer a lower noise level less oil-content Copper and Aluminium Designs for the same efficiency: 15-May-02 20 Copper and Aluminium Designs for the same efficiency Dry-type versus oil-filled transformers: 15-May-02 21 Dry-type versus oil-filled transformers higher initial cost higher no-load losses lower load losses harmonics cause less extra heating and ageing better fire protection no oil spilling container Full load losses in a 100kVA C-C’ transformer: 15-May-02 22 Total loss = 1685 W Full load losses in a 100kVA C-C’ transformer Harmonic profile of a typical Personal Computer: 15-May-02 23 Harmonic profile of a typical Personal Computer Full load losses in a 100kVA C-C’ transformer: 15-May-02 24 Total loss = 3245 W Full load losses in a 100kVA C-C’ transformer Effect of additional losses on life-time: 15-May-02 25 where T is working temperature at rated fundamental power, P f ,, P k is the total power and T is the rated life-time in years Effect of additional losses on life-time Harmonic culture: 15-May-02 26 Harmonic culture Economic evaluation: 15-May-02 27 Economic evaluation 2 approaches to buy a transformer Specify Po and Pk Specify A & B factors Ct = Purchase price + A * Po + B * Pk With I = interest rate 7% n = lifetime 30 yrs C kWh = cost / KWh 0.05 c I l /I r = loading 50% Example: 15-May-02 28 Example 1600 KVA, 50% load, oil-cooled: (A = 5.4 euro / Watt; B = 1.3 euro / Watt) Efficiency AA’ CC’ Purchase 9,700 € 10,300 € Load loss 22,100 € 18,200 € (1.3 * 17,000) (1.3 * 14,000) No load loss 14,040 € 9,180 € (5.4 * 2,600) (5.4 * 1,700) Total 45,840 € 37,680 € A and B values for selected countries: 15-May-02 29 A and B values for selected countries Lifetime owning cost 400 kVA oil-cooled: 15-May-02 30 Lifetime owning cost 400 kVA oil-cooled Beyond the magic of A & B: 15-May-02 31 Beyond the magic of A & B Example - revisited: 15-May-02 32 Example - revisited 1600 KVA, 50% load, oil-cooled: Efficiency AA’ CC’ Purchase 9,700 € 10,300 € Load loss 1,850 € / yr 1,533 € / yr No load loss 1,140 € / yr 745 € / yr Result Payback 10 months IRR 119% @ 30 years Ecological evaluation: 15-May-02 33 Ecological evaluation 1600 KVA, 50% load, oil-cooled: Efficiency AA’ CC’ Energy 210 GWh 210 GWh transformed No load loss 684 MWh 447 MWh Load loss 1,110 MWh 921 MWh Emissions 718 tonnes 547 tonnes Emission savings 171 tonnes Soft benefits: 15-May-02 34 Soft benefits Save energy Save emissions Noise? Reduced heating Improved lifetime Reliability? More robust against harmonics What’s the catch?: 15-May-02 35 What’s the catch? Increased capital outlay Commercial policy of suppliers Small amounts Risk of being a pioneer Energy & emission savings potentials related to transformers & standby power: 15-May-02 36 Energy & emission savings potentials related to transformers & standby power More information: 15-May-02 37 More information www.efficient-transformers.org electronic library calculation tools K-Factor & Factor K Investment evaluation spreadsheet www.supertrafo.com daily, on-line measurement of energy saving for 4 high efficiency transformers installed in Poland PowerPoint Presentation: 15-May-02 38 PowerPoint Presentation: 15-May-02 39 Super-trafo demonstration: 15-May-02 40 Super-trafo demonstration Conclusions: 15-May-02 41 Conclusions Evaluate transformers for lifetime cost oil-cooled Buy only CC’ or higher Evaluate transformer with 15-20% less loss than CC´ dry-type if you need the advantages evaluate transformer with 15% less loss than HD538 Check harmonic culture Consider replacement of veteran transformers

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