CHARACTERISTICS

The use of electric motors requires that the distribution system deliver a form of power known as "reactive power". This is generally not a problem for residential power distribution, due to the limited number and small size of motors. Commercial and industrial users often require large quantities of reactive power, which increases current and energy losses. Connecting capacitors to the distribution system compensates for the reactive power, and reduces current and energy losses back through the system, since transmission losses are related to current and line resistance.

When reactive power-related losses are minimized, generation demand and the corresponding GHG emissions are reduced.

SIZE:
Power factor correction capacitors for application on primary distribution feeders are commercially available for use on the full range of voltage levels and in practical kVAr sizes.

FEATURES:
Power factor correction capacitors can be installed with switches and relays that sense low and high voltage. The insulating fluid used in early capacitors contained PCB, but new insulating fluids are now in use.

COST:
The cost of power factor correction capacitors installed on primary distribution feeders in close proximity to low power factor loads is in the range of $12-20 per kVAr.

CURRENT USAGE:
Power factor correction capacitors are in common use on primary distribution systems through out the world.

POTENTIAL USAGE:
Every utility can benefit from installing more efficient capacitors.

ISSUES ASSOCIATED WITH IMPLEMENTING ACTION

• Customers are reluctant to correct their own power factor, especially where rate tariffs do not allow a penalty for large users.
• Possible negative impacts on power quality.
• Energy loss reductions alone do not offset the capital costs of required new equipment.
• There are operating and maintenance (O&M) costs associated with many dispersed capacitor installations, and failure of accessory (fuses, switches, etc.) equipment is common.
• The VAR control function can be optimized under the Distribution System Automation Option.

CLIMATE CHANGE IMPACT

EMISSION EFFECT:
    

CONDITIONS FOR EMISSIONS MITIGATION:

• When losses are reduced, GHG emissions are also reduced due to the accompanying reduction in demand for generation.

EMISSION ESTIMATE:
Varies according to the fuel mix used in generation.

COST-EFFECTIVENESS:
Total losses of 9% are attributable to transmission and distribution from the point of generation to the point of use. From 2-3% of the total can be assigned to losses in feeder conductors and transformers.

SECONDARY EFFECTS:
Varies according to the generation fuel mix.

RESOURCES

• The U.S. Department of Energy sponsors a Real Time System Control Program, that awards contracts to utility consultants, manufacturers and universities.

CONTACTS

Harza Engineering
Peter Donalek
Electric Power Systems Department
Chicago, IL
Tel: (312) 831-3170
Fax: (312) 831-3999
pdonalek@harza.com
http://www.harza.com

National Rural Electric Cooperative Association (NRECA)
James Willis
Electrical Engineer
International Programs Division
Arlington, VA
Tel: (703) 907-5669
Fax: (703) 907-5532
Jim.willis@nreca.org
http://www.nreca.org