Transferring reactive power into electrical energy supply equipment results in a considerably higher absorption of current than results from simply transferring active power, see diagram below. This in turn results in unnecessary losses in power transmission and the need to oversize electrical equipment.
Energy suppliers therefore charge for the delivery of reactive power on the basis of 15-minute averages.
By using reactive power compensation systems, energy consumers can reduce their imports of reactive power from the energy supplier to a level for which there is no charge. There are therefore no ongoing costs for the import of reactive power. Investments in reactive power compensation systems usually pay for themselves in the first one to two years of operation.
Using compensation systems in plant grid can also make a positive difference because transfer losses can be minimized, transformer and line loads can be reduced and oversizing can be avoided.
This improves the operating reliability of the energy supply grid, extends the equipment's service life and reduces investments in equipment. Incorporating the distortion reactive power caused by harmonics as part of overall reactive power results in the following:
P= active power S= apparent power S
Q= displacement reactive power D= distortion reactive power D
To reduce the reactive power in the 15-min. average, capacitor stages are activated in a regulated manner. The aim is to comply with the target power factor.
The reactive power requirement of e.g. an engine can be provided by a compensation system. Inductive and capacitive reactive power are therefore compensated for and don't load the grid elements upstream of where the load and compensation intersect. The power factor is permanently readjusted by a reactive power controller in the event of fluctuating load which ensures compliance with the utility company requirements.