Energy Efficiency by Power
Factor Correction
Reducing energy costs
Reducing grid losses and CO2 emissions
ZVEI - Zentralverband Elektrotechnikund Elektronikindustrie e. V.
Fachverband Starkstromkondensatoren
Lyoner Straße 9
60528 Frankfurt am Main
Fon: 069 6302-440
Fax: 069 6302-413
Mail: starkstromkondensatoren@zvei.org
www.zvei.org
Energy Efficiency by Power Factor Correction
Advantages of Power Factor Correction – an overview
Advantages of Power Factor Correction – an overview
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How reactive power originates
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Effects of reactive power
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Power factor correction
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Economic Advantages of Power Factor Correction
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Network losses – Status and Potential in Germany
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Technology of Power Factor Correction Systems
Further advantages
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One technique that has been used for many years to
promote the efficient use of electrical energy is power
factor correction (PFC).
A major economic advantage of this is that the consumer cuts down on energy costs. In addition, power factor correction reduces the amount of current flowing in
the transmission and distribution networks. Reduced
current levels mean lower power losses in the distribution network, savings in electrical energy and hence
reduced CO2 emissions.
Power factor correction
= Decreased power losses
= Reduced CO2 emissions
= Active climate protection!
Calculations show that in 2007 the power factor correction systems then installed in Germany reduced
network losses by about 5.5 billion kilowatt-hours.
Expressed in terms of the energy source mix conventionally applied to Germany, this is equivalent to nearly 3 million tonnes of CO2 emissions that were thus
avoided.
Power factor correction offers the potential for a
further reduction in network losses of some 3.5 billion
kilowatt-hours from present-day levels, equivalent to
cutting CO2 emissions by nearly 2 million tonnes per
annum.
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Energy Efficiency by Power Factor Correction
How reactive power originates
Energy Efficiency by Power Factor Correction
Power Factor Correction
Many electrical devices, such as AC single-phase and
3-phase motors, require both active power and reactive power. The active power is converted into useful
mechanical power, while the reactive power is needed
to maintain the device’s magnetic fields. This reactive
power is transferred periodically in both directions between the generator and the load.
Effects of reactive power
Power stations and transmission network operators
must make the apparent power S (see figure) available and transmit it. This means that generators, transformers, power lines, switchgear, etc. have to be dimensioned for greater power ratings than if the load
only drew active power. Power supply companies are
therefore faced with extra expenditure on plant and
additional power losses. They therefore make additional charges for reactive power if this exceeds a certain
threshold.
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If the lagging power factor is corrected, for example
by installing a capacitor at the load, this totally or partially eliminates the reactive power draw at the power
supply company. Power factor correction is at its most
effective when it is physically near to the load and can
respond rapidly.
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Energy Efficiency by Power Factor Correction
Energy Efficiency by Power Factor Correction
Economic Advantages of Power Factor Correction
Saving the costs of reactive energy
As an example we can take an industrial company with
an average power of 500 kW, operating for 4000 hours
per annum at an average cos wi of 0.7. The power
supply tariff allows the user to draw 50% of the active
energy as reactive energy at no extra charge, corresponding to a target cos wi of 0.9. The payback time of
less than one year illustrates the enormous economic
viability of power factor correction.
Part of annual energy bill
Energy at normal tariff
Reactive energy at normal tariff
Reactive energy at no charge
Chargeable reactive energy
2,000.000 kWh
2,040.408 kvarh
1,000.000 kvarh
1,040.408 kvarh
Additional savings from reduced active power
losses
The company taken as example has power losses in its
own distribution network, and, like every other consumer, must pay the cost of the active energy lost. The
use of power factor correction reduces the apparent
power in the company network, and hence also the power losses and the costs for active energy. In addition
to saving reactive energy costs, the power factor correction system in this example also reduces the costs
for the active power expended on network losses by
several hundred € annually.
Reduction in investment costs
Our company is planning to extend its facilities, and
increase its power demand by 200 kW from the present
level of 500 kW. The existing transformer with a rating
of 800 kVA has been adequate to date, but would be
overloaded after the plant expansion, making it necessary to extend the power infrastructure with a transformer, switchgear, cabling, distribution board, etc. In
this case the apparent power can be reduced by means
of power factor correction so that the existing infrastructure is still adequate. A power factor correction
system is significantly less expensive than a network
expansion.
Power factor correction
reduces both energy costs
and investment costs.
x 0.013 €/kvarh = € 13,525
Required PFC capacity
Installed PFC capacity
268 kvar
300 kvar
Investment cost incl. installation = ca. € 8,000
Payback period = ca. 7 month
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Energy Efficiency by Power Factor Correction
Energy Efficiency by Power Factor Correction
Network losses – Status and Potential in Germany
Power factor correction reduces the apparent power in
a network, and thus the current loading in the same
proportion.
5% less current = 10% lower losses.
The power factor cos wi is an indication of the proportion of reactive power in a network. The graph on the
right illustrates how the current loading and network
losses depend on the power factor, with the case when
cos wi equals 1 (i.e. with full power factor correction)
being defined as 100%.
The lower the power factor, the higher the reactive power, current loading and network losses. This applies
just as much to the power consumer’s (industrial or
special contract customer’s) own distribution network
as to the general transmission and distribution networks for the supply of electric power.
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Power factor correction reduces network losses in
Germany
The effect of power factor correction on the magnitude of network losses is analysed by examining three
scenarios:
Scenario 1: No PF correction Scenario 2: Partial PF correction Scenario 3: Target PF correction
Network losses without existing power factor correction
systems
Status quo with partial power Network losses with the maxifactor correction to a cos wi mum reasonable use of power
of 0.90
factor correction (full compensation and target cos wi = 0.95)
Comparison of Scenario 2 with Scenario 1 shows that:
• The existing power factor correction systems already installed reduce annual network losses by 5.5 billion kWh.
• This is roughly equivalent to 2.86 million tonnes CO2 or
the electricity consumption of 1.83 million households.
Comparison of Scenario 3 with Scenario 2 shows that:
• With the maximum reasonable use of power factor
correction, there is the potential for a further reduction in
network losses of 3.5 billion kWh.
• This is almost equivalent to 1.83 million tonnes CO2 or
the electricity consumption of 1.17 million households.
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Energy Efficiency by Power Factor Correction
Energy Efficiency by Power Factor Correction
Technology of Power Factor Correction Systems
Complete panel for power factor correction
Power factor correction systems are low voltage systems which are erected in the course of building installation. They are to be regarded as self-contained units.
The systems are connected to the existing building installation and can also be retrofitted without any major
adaptations.
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Power factor controller and PF correction capacitor
Monitoring and control of the system are performed
independently by corresponding controllers which are
normally integrated in the system. These controllers
automatically regulate the reactive power factor to the
target cos wientered.
Correction itself is performed by the PF correction capacitors installed in the system. These capacitors are
specially developed and manufactured for this application.
Power factor correction must take place rapidly and
close to the load, i.e. directly at the machine generating the reactive power, so that reduction of the burden on the transmission channels and thus reduction
of losses are optimally effective.
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Energy Efficiency by Power Factor Correction
Energy Efficiency by Power Factor Correction
Further advantages
Enhanced network voltage quality
An additional positive effect can be achieved by the application of de-tuned power factor correction systems
and filter circuits. These have the property of suppressing harmonics. This effect enhances the quality of the
power supply, since the desired sinusoidal waveforms
are achieved for voltage and current, and no harmonic
currents then flow into the distribution and transmission networks. Less harmonic current flowing in the
networks therefore means further reductions in power
losses and CO2 emissions.
Increased network capacity
As previously shown in connection with the additional
grid losses, power factor correction relieves the network
of the unnecessary transmission of reactive power. There is currently discussion on the grid reaching its limits
in the wake of increased electricity trading and rising
input from wind farms. Even if power factor correction
surely cannot replace further expansion of the grid or
can only assist in individual cases, the additional capacity set free by greater use of power factor correction
would free some bottlenecks which have already been
identified and gain urgently needed time to implement
the further expansion.
Impressum
Energy Efficiency by Power Factor
Correction
Although great care has been exercised
to ensure accuracy, no liability can be
accepted for the contents of this publiPublished by:
cation.
ZVEI - Zentralverband ElektrotechnikAll rights reserved, especially those of
und Elektronikindustrie e.V.
duplication, distribution and translati(German Electrical and Electronic
on. No part of this publication may be
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Editor: Johannes Stein
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April 2008 edition
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Energy Efficiency by Power Factor Correction
Energy Efficiency by Power Factor Correction
EnQ – the ZVEI Energy Intelligence Initiative for the intelligent use of energy-efficient technologies.
Reducing greenhouse gas emissions is one of the
central challenges facing government, society and
industry in Germany. European and national politicians have set ambitious goals in this respect: By
2020, these emissions are to be reduced by at least
30 percent from the 1990 level. At the same time, the
German government has set a target of doubling energy productivity by 2020 in comparison with 1990. The
electrical and electronics industries are making a decisive contribution to this process with their intelligent
and energy-efficient technologies. The consistent use
of intelligent technologies would already be capable
of reducing power consumption by around 40 billion
kWh, corresponding approximately to the annual consumption of a state as large as Hessen. Nevertheless,
these technologies are not as yet being optimally exploited.
ZVEI, through its Energy Intelligence Initiative “EnQ”,
is therefore promoting the intelligent use of energyefficient technologies.
www.en-q.de – the initiative’s Internet platform
Condensator-Dominit Dr. Christian Dresel
Gesellschaft für Leistungselektronik, Energietechnik und
Netzqualität mbH
Telefon +49 2961 782 21 • www.condensator-dominit.de
ELECTRONICON Kondensatoren GmbH
Fon +49 365 7346 0 • www.electronicon.com
EPCOS AG
Fon +49 89 636 21051 • www.epcos.com/pfc
FRAKO Kondensatoren- und Anlagenbau GmbH
Fon +49 7641 453 0 • www.frako.de
KBR GmbH
Fon +49 9122 63 73 0 • www.kbr.de
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Maschinenfabrik Reinhausen GmbH
Fon +49 361 30103 11 • www.reinhausen.com
Modl GmbH
Fon +49 9143 603 0 • www.modl.de
Schneider Electric GmbH
Fon +49 180 575 3 575 • www.schneider-electric.de
System Electric Power Quality GmbH
Fon +49 6051 74158 • www.system-electric.de
Vishay Electronic GmbH
Fon +49 871 862594 • www.vishay.com/capacitors
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