Gruppi di continuità (UPS) Marco Liserre.

Transcription

1 Gruppi di continuità (UPS)

2 Gruppi di continuità Uninterruptible Power Supplies: UPS E un dispositivo che cerca di garantire una alimentazione continua ai carichi ad esso connessi alimentandoli da una diversa sorgente nel caso di interruzioni nella alimentazione da rete elettrica Principali tipi di UPS: statico: basato su un convertitore statico di potenza e un sistema di immagazzinamento energetico dinamico: basato su un motore/generatore ibrido: usa sia un motore che un convertitore statico

3 Distorsione nella tensione di ingresso buchi di tensione sovratensioni abbassamenti di tensione (brownout) interruzione (blackout) picchi di tensione (spike) buchi di tensione armoniche interferenza elettromagnetica (EMI) armoniche Tratto da N. Mohan, T.M. Undeland, W.P. Robbins Elettronica di potenza HOEPLI, slides di presentazione Prof. Andriollo

4 Schema generale di UPS linea AC raddrizzatore inverter filtro carico critico banco batterie sono disponibili mezzi alternativi alle batterie Pb-acido per l accumulo energetico Tratto da N. Mohan, T.M. Undeland, W.P. Robbins Elettronica di potenza HOEPLI, slides di presentazione Prof. Andriollo

5 Passive standby UPS (off-line) Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

6 Passive standby UPS (off-line) Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

7 Line interactive UPS Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

8 Line interactive UPS Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

9 Double conversion UPS (on-line) Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

10 Double conversion UPS (on-line) Tratto da Josep M. Guerrero, Uninterruptible Power Supply (UPS) Systems, Student tutorial ISIE 2007, Vigo (Spagna)

11 Tratto da M. Guerrero, L. García de Vicuña, J. Uceda Uninterruptible Power Supply Systems provide protection IEEE Industrial Electronics Magazine, 2007.

12 Sistemi di accumulo s 1000 Specific energy [Wh/kg] Flowbattery Ni-Cd Pb-battery High temp battery Room temp adv battery Hybrid comp air Medium-speed flywheel High-speed flywheel Supercap 360 s 36 s 3,6 s Peak Power [W/kg] Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

13 Lead Acid batteries most commonly used energy storage systems for UPS Continuous power W/kg Deliverable energy Wh/kg Typical back-up time 5-30 min System price: Deliverable energy $/kwh System price: Power $/kw Advantages Proven technology Low cost Very low standby losses High modularity Drawbacks Sensitivity to temperature Large volume and weight Limited charge/discharge cycles High failure rate Environmental impact Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

14 Supercap Continuous power W/kg Deliverable energy 1-3 Wh/kg Typical back-up time sec System price: Deliverable energy $/kwh System price: Power $/kw Advantages Drawbacks Wide operating temperature range Many charge/discharge cycles Maintenance-free Very high power density Very low standby losses Long service life Short charging time Low environmental impact Cost Low energy density Voltage balancing Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

15 Medium speed Flywheel mechanical storage, wheel speed rpm Continuous power W/kg Deliverable energy Wh/kg Typical back-up time sec System price: Deliverable energy $/kwh System price: Power $/kw Advantages Wide operating temperature range Many charge/discharge cycles High power density Very long service life Short charging time Low environmental impact Drawbacks Cost Low energy density Stand-by losses Maintenance Audible Noise Installation Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

16 High speed Flywheel mechanical storage, wheel speed rpm Continuous power W/kg Deliverable energy 1-3 Wh/kg Typical back-up time sec System price: Deliverable energy $/kwh System price: Power $/kw Advantages Wide operating temperature range Many charge/discharge cycles High power density Very long service life Short charging time Low environmental impact Drawbacks Cost Low energy density Maintenance Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

17 Discussion back-up systems seconds runtime VRLA HS Flywheel MS Flywheel Supercapacitors service life [year] >10 Charge/Discharge cycles > 500'000 Charging efficiency [%] Operating temperature [ C] 10 to 30 0 to 40 0 to to 65 Typical back-up time 5min-30min sec sec sec Continuous power [W/kg] Deliverable energy [Wh/kg] Losses stand-by very low low high low Predictive Monitoring medium good good good Modularity very good good good very good Environmental impact high low low low Maintenance 1 check/year 1 check/5year 1 check/year no Current energy price [$/kwh] Current power price [$/kw] Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

18 Advantages High energy density Insensitive to ambient temperature Maintenance free construction Long service life Low environmental impact Short charging time Unproblematic storage Drawbacks Current cost Management electronic needed Put into operation time (>1day) Fast self-discharge (< 2 weeks) Sodium Nickel Chloride Continuous power 120 W/kg, Deliverable energy 50 Wh/kg Typical back-up time 30min-hours System price: Deliverable energy $/kwh Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

19 Compressed air systems Continuous power W/kg Deliverable energy 5-10 Wh/kg Typical back-up time 5-30min System price: Deliverable energy $/kwh Advantages Wide operating temperature range Many charge/discharge cycles Very long service life (20 years) Low environmental impact Drawbacks Current cost Stand-by losses Energy density Complex system Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

20 Discussion back-up systems min-hours runtime Lead Acid Hybrid compressed air systems Flow battery Sodium Sulphur Sodium Nickel Chloride Nickel Metal Hydride Lithium Ion service life [years] > Charge/Discharge cycles 1000 >10000 >2000 >800 > >1000 Charging efficiency [%] Operating temperature [ C] 10to30 0to40 0to50-40to50-20to40-20to45 Typical back-up time 5min-30min 5min-30min hours hours >25min minutes minutes Continuous power [W/kg] Deliverable energy [Wh/kg] Losses stand-by very low moderate moderate low low moderate moderate Predictive Monitoring moderate good good moderate good moderate moderate Modularity high good moderate high good high high Environmental impact high low low low low low low Maintenance requirements moderate low moderate low low moderate moderate Current price [$/kwh] Future price [$/kwh] Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS

21 Summary and conclusions Today energy storage systems UPS systems today: Lead-Acid batteries/gensets long back-up (>30 minutes) Energy storage comprise 30 to 60% of cost and space of entire power quality systems Lead-Acid drawbacks: footprint/weight, sensitivity to temperature, failure rate, toxic chemicals Alternative energy storage systems Double layer capacitors and medium/high speed Flywheel interesting alternative for back-up time up to 20 seconds, considering: technical maturity, performances and costs Advanced batteries and hybrid compressed air systems with current performances, level of maturity and potential for cost reduction, can be used with the next UPS generation Tratto da Marco Piemontesi, GE Digital Energy Riazzino, Alternative Energy Storage Systems for UPS