Power Factor Correction (PFC): energy optimization Workshope Electromechanical technoogies: the Italian supply system for energy infrastructures

1. Power factor correction (PFC):
energy optimization
DAMASCUS,
Ministry of Electricity
24th November 2009

2. Pier Luigi Farina
Export Manager Capacitors and
Systems Div. – DUCATI ENERGIA

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. 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. 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. 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. 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. 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. 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. LV PFC systems

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. LV PFC systems “racks”
- on the floor up to 1600kVAR,
1600kVAR
- forced cooling,
- cable inlet from the top,
- rack structure.

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. 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. MV/HV PFC systems

16. MV capacitor banks 24-36kV

17. MV capacitor banks up 230kV

18. MV/HV harmonic filters

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. 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. MV/HV PFC protection
Unbalance relays for Y-Y banks
Expulsion fuses and HRC fuses
Unbalance CT for Y-Y banks

22. Thank you