Capacitor Application

• Capacitors provide benefits to distribution system performance.

• Benefit of Capacitors application :

– Improve power factor

– Reduce losses,

– Reduce voltage drop or improve voltage regulation

– Release Capacity

Capacitor vs Loss Reduction

• Capacitor can reduce losses in distribution network by :

– Canceling the reactive power to motors and other loads with low power factor

– Decrease the line current

Capacitor vs voltage drop

• Application of capacitor also can improve voltage profil or reduce voltage drop,

• Capacitors provide a voltage boost, which cancels part of the drop caused by system loads.

• Switched capacitors can regulate voltage on a circuit

• If applied properly and controlled, capacitors can significantly improve the performance of distribution circuits.

• But if not properly applied or controlled, the reactive power from capacitor banks can create losses and high voltages.

• Good planning helps ensure that capacitors are sited properly

• More sophisticated controllers reduce the risk of improperly controlling capacitors

Capacitor Installation

• Capacitor units are made of series and parallel combinations of capacitor packs or elements put together

• Utilities often install substation capacitors and capacitors at points on distribution feeders.

• Most feeder capacitor banks are pole mounted, while some manufacturers provide padmounted capacitors.

• Many capacitors are switched, either based on a local controller or from a centralized controller

• Utilities normally apply capacitors on three-phase sections.

• Most utilities also include arresters and fuses on capacitor installations.

• Arresters protect capacitor banks from lightning-overvoltages.

• Fuses isolate failed capacitor units from the system and clear the fault before the capacitorfails violently.

Individual capacitors can be connected in parallel to achieve the desired kVAr capacity

Individual capacitors can be connected in series to achieve the required kV voltage

Substation vs feeder capacitor

Substation Capacitor

• Substation capacitors and feeder capacitors both have their uses.

• Feeder capacitors are closer to the loads

• Capacitors closer to loads more effectivelyrelease capacity, improve voltage profiles, and reduce line losses.

• This is especially true on long feeders that have considerable line losses and voltagedrop.

Substation Capacitor

• Substation capacitors are better when more precise control is needed.

• Substation capacitors may also be desirable if a leading power factor is needed for voltage support.

Series vs Shunt Capacitor

• Fundamental function of capacitor, whether they are series or shunt, is to regulate the voltage and reactive power flows at the point they are installed

• Shunt capacitor does it by changing power factor of the load.

• Series capacitor does it by directly offsetting inductive reactance of the circuit to which it is applied

Series capacitor

• Series capacitor compensate inductive reactance• Therefore, primary effect of series capacitor is to minimize

voltage drop caused by the inductive reactance in the circuit

• Series capacitor can be considered as voltage regulator that provides for voltage boost which is propotional to the magnitude and power factor of the through current.

• Series capacitor provides for a voltage rise which increase as load grows

• Series capacitor also provides more net voltage rise than shunt capacitor at lower power factor

• However series capacitor, than a shunt capacitor, has a little effect on the source current.

Shunt Capacitor

• Shunt capacitors connected parallel to the lines.

• They supply reactance power or current to counteract reactive current required by inductive loads.

• Shunt capacitor benefits– Reduce source current

– Improve power factor

– Reduce voltage drop

Power Factor correction

• Power Triangle

Before correction

After correction

Capacitor Economic

• Properly applied capacitors return their investment very quickly.

• Capacitors save significant amounts of money in reduced losses.

• In some cases, reduced loadings and extra capacity can also delay building more distribution infrastructure.

Capacitor Economic

• Economic benefits from capacitor installation :

– Released generation capacity

– Released transmission capacity

– Released distribution substation capacity

– Additional ecenomic advantage from :

• Reduced energy losses

• Reduced voltage drop (improved voltage regulation)

• Released capacity of feeder and associated apparatus

• Revenue increase due to voltage improvement

Benefit due to released generation capacity

Benefit due to released generation capacity

Benefit due to released transmission capacity

• Released transmission capacity

• Annual Benefits

Benefit due to released distribution substation capacity

• Released capacity

• Annual benefits

Benefit due to reduced Energy losses

Benefit due to released feeder capacity

• Released feeder capacity

• Annual benefits

Financial benefits due to voltage improvement

• Increase revenue due to increased kWh energy consuption

Total benefits due to capacitor installation

• Total benefits

• Total benefits should be compared with annual equivalent of total cost of capacitor