PFC - Ducati ANIE 2009


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Power Factor Correction (PFC): energy optimization

Workshope Electromechanical technoogies: the Italian supply system for energy infrastructures

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PFC - Ducati ANIE 2009

  1. 1. Power factor correction (PFC): energy optimization DAMASCUS, Ministry of Electricity 24th November 2009
  2. 2. Pier Luigi Farina Export Manager Capacitors and Systems Div. – DUCATI ENERGIA
  3. 3. Cos φ In electrical circuits the current is in phase with the voltage in case of resistive loads, whereas the current is lagging when the load is inductive (motors, transformers with no load conditions) and leading when the load is capacitive (capacitors). P cos ϕ = A The reactive power (Q) doesn't produce mechanical work and it is an additional load for the energy supplier. The parameter defining the absorption of reactive power is the power factor. factor
  4. 4. PFC main target A power factor correction system, connected in parallel with the other loads, will reduce the amount of reactive inductive power to be supplied by the electricity supply companies, thus reducing or eliminating the overcharges for excessive reactive power absorption.
  5. 5. PFC advantages In addition to the immediately profitable effect, power factor correction also offers important technical advantages. An increase of cosϕ considerably reduces Power Losses (heat) in power transmission lines, thus slowing down the ageing process. Increasing cos φ from 0,7 to 1 means: • around 50% less costs due to network resistive losses. • around 50% extra current availability in the network. An increase of cosϕ will reduce on-line Voltage Drop, thus ensuring better user Drop performance, the line voltage along the line being closer to its rated power.
  6. 6. PFC size and choice To properly size a PFC system both its quantitative and qualitative aspects of the load power factor have to be taken into due consideration: 1) the power factor correction rate (kVAr) to be installed to avoid surcharges, by means of the analysis of consumption. 2) the expected capacitor working conditions (environment and power mains), which must be evaluated particularly as far as the presence of harmonics in the line is concerned. Type of PFC The choice of the correct power factor correction equipment depends on the type of loads present and by their way of working. Individual Central compensation compensation Individual compensation is most effective if the majority of the reactive power is concentrated on few loads with high power and that work for long period of time. Central compensation is best suited for systems where the load fluctuates through out the day. If the absorption of reactive power is variable, it is advisable the use of automatic regulation than fixed capacitors.
  7. 7. PFC with harmonic distortion The distortions of the current waveforms are generated by non-linear loads (inverter, saturated transformers, rectifier, etc.) and produce the following problems: - mechanical vibration on the A.C. motors that can reduce the life. The increase of the losses creates overheating and damaging of the insulating materials; - increasing the copper and iron losses of transformers with possible damaging of the windings and increasing of magnetizing currents; - capacitors suffer from the increasing of the voltage that reduce the life. - flickers in the network. The dimensioning of PFC systems with tuned or detuned filters is linked to: - impedance of the network. - presence of possible and further loads that generate harmonics linked to other nodes on the network. - capacitor types: the eventual capacitance decrease varies the series resonance frequency and this inconvenient could be very dangerous because the system could have parallel resonance. To have the guarantee of a constant capacitance during the time it is necessary to use durable capacitors. Besides the tuned filter made of capacitors and reactors (passive filter) it is possible, to remove the harmonics in the network (Power Quality), to use another type of construction Quality of tuned filter: the Active Filter. The working is based on the injection in the network of the Filter same current harmonics created by the non-linear loads but with inverted angle phase.
  8. 8. Power capacitors for LV/MV MV SINGLE-PHASE SINGLE- LV SINGLE-PHASE CYL. SINGLE- POWER: 25kvar to 800kvar POWER: 0.5kvar to 10kvar VOLTAGE: 1kV to 36kV VOLTAGE: 230V to 690V LV THREE-PHASE CYL. THREE- POWER: 1kvar to 30kvar VOLTAGE: 230V to 1000V MV THREE-PHASE THREE- POWER: 25kvar to 700kvar LV THREE-PHASE MODULAR THREE- VOLTAGE: 3kV to 12kV POWER: 2,5kvar to 60kvar
  9. 9. Power capacitors technology The most important materials in power capacitors are dielectric film (metallized polypropilene or polypropilene/aluminum used to manufacture the capacitive element) and impregnating material (resin or oil used to wrap, protect and insulate the capacitive element). The metallized PP film, used in LV application, is self-healing and the metalization is application composed by zinc and aluminium. Self-healing means that in case of a localized short circuit (or break down) in a single layer of film, this results in a small arc that evaporates the metallization in the local region of the short circuit (in a matter of microseconds). This means that a non-conducting isolation region free of metalization is formed there without discontinuing the capacitor operation. 100 90 80 70 60 L ife% 50 100 40 90 30 80 20 70 10 60 0 L ife% 50 55 60 65 70 75 80 40 °C Temperature 30 20 10 0 1 1,05 1,1 1,15 1,2 1,25 1,3 1,35 1,4 1,45 1,5 Un/U Overvoltage LV PFC capacitors are manufactured according to IEC831 MV PFC capacitors are manufactured according to IEC871
  10. 10. LV PFC systems
  11. 11. LV PFC systems “modular” - on the floor up to 400kVAR, 400kVAR - forced cooling, - cable inlet from the top, - modular structure. - wall mounted up to 200kVAR, 200kVAR - natural cooled, - cable inlet from the top, - modular structure.
  12. 12. LV PFC systems “racks” - on the floor up to 1600kVAR, 1600kVAR - forced cooling, - cable inlet from the top, - rack structure.
  13. 13. PFC real-time & active filters • Thanks to the use of electronic controllers and switching devices, real-time power factor correction systems can compensate reactive power within one cycle of the network (20ms) by means of “soft” switching in and out of capacitor banks. This makes it possible to “track” the Power Factor, so track as to optimize the efficiency of the distribution network. • Both in industry and the public sector, we are witnessing a growing use of equipment incorporating AC DC conversion systems: this has resulted in an increased need for harmonic compensation and fast power factor correction solutions. Active filters and real-time power factor correction systems may successfully compete with current systems in terms of cost while offering all the advantages of the new technology.
  14. 14. Advantages of “real-time” • Capacitor switching “zero-crossing” voltage peaks Arc welder operating cycle without/with “real-time” real- time” • Complete compensation of inductive reactive power absorption within one network period (20 ms) • Energy savings, they are more efficient than traditional power factor correction systems • Increase in the active power transmission capability within the network • Drastic reduction in voltage drops and flickering • Reduction in circulating currents Induction motor starting with/without “real-time” real- time” • Prevention of costly downtimes caused by the Voltage [V] tripping of automatic cutout devices due to excessive voltage and current drops. • Prevention of wear (on contacts and capacitors). Senza “real time”: Con “real time”: Avviamento fallito Avviamento OK • They eliminate the need to install starter devices Current [A] (soft starters, inverters) for each individual unit of equipment. • They enhance the delivery capacity of any local generators.
  15. 15. MV/HV PFC systems
  16. 16. MV capacitor banks 24-36kV
  17. 17. MV capacitor banks up 230kV
  18. 18. MV/HV harmonic filters
  19. 19. MV PFC panels up to IP55 PFC IP30 panel with contactor inrush current limiting reactors PFC IP55 panel with detuned reactors and switch for outdoor desert installation PFC IP30 panel with no-load switch and detuned reactors
  20. 20. RC filters & Induction furnace RC FILTERS for primary & secondary of Electric Arc Furnace Transformers INDUCTION FURNACE CAPACITORS POWER: 25kvar to 700kvar VOLTAGE: 600V to 3kV FREQUENCY: 50Hz to 500Hz
  21. 21. MV/HV PFC protection Unbalance relays for Y-Y banks Expulsion fuses and HRC fuses Unbalance CT for Y-Y banks
  22. 22. Thank you