Presented by:-SWAGAT KUMAR GURURegd. No:-0901223354

Roll No:-09EE055

Under the guidance ofMs. Samprati Mohanty

(Advisor)

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DEFINITION CAUSES OF LOW POWER FACTOR

POWER FACTOR CORRECTION

ADVANTAGES OF POWER FACTOR CORRECTION

DISADVANTAGES OF LOW POWER FACTOR

CONCLUSION

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DEFINITION:- Power factor (P.F) is the ratio between

actual power to the apparent power. P.F= Actual power/Apparent power. =kw/kva

For a purely resistive load the power factor is unity. Active and reactive power are designated by P &Q respectively. The average power in a circuit is called active power and the power that supplies the stored energy in reactive elements is called reactive power.

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A poor power factor can be the result of a significant phase difference between the

voltage and current at the load terminals OR

it can be due to a high harmonic content or distorted/discontinuous current waveform.

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Poor load current phase angle is generally the result of an inductive load such as an induction motor power transformer, lighting ballasts, welder or induction furnace, Induction generators ,Wind mill generators and high intensity discharge lightings.

A distorted current waveform can be the result of a non-linear load like rectifier variable speed drive, switched mode power supply, discharge lighting or other electronic load.

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Most loads on an electrical distribution system fall into one of three categories; resistive, inductive or capacitive.

In most plant, the most common is likely to be inductive.

Typical examples of this include transformers, fluorescent lighting and AC induction motors.

Most inductive loads use a conductive coil winding to produce an electromagnetic field, allowing the motor to function.

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All inductive loads require two kinds of power to operate:

Active power (KW) - to produce the motive force

Reactive power (KVAR) - to energize the

magnetic field

The operating power from the distribution system is composed of both active (working) and reactive (non-working) elements.

The active power does useful work in driving the motor whereas the reactive power only provides the magnetic field.

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It is not usually necessary to reach unity, i.e. Power Factor 1, since most supply companies are happy with a PF of 0.95 to 0.98.By installing suitably sized switched capacitors into the circuit, the Power Factor is improved and the value becomes nearer to 1 thus minimising wasted energy and improving the efficiency of a plant or power factor can be increased by synchronous motor or Synchronous generators.

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Static Var Compensator(SVC)

Capacitor banks

Synchronous Condensors

Static Synchronous Compensator(STATCOM)

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The Static VAr Compensator is a thyristor controlled(hence static) device which controls the flow of reactive power in a system by generating or absorbing reactive power.

The SVC regulates voltage at its terminals by controlling the amount of reactive power injected into or absorbed from the power system.

When system voltage is low, the SVC generates reactive power (SVC capacitive). When system voltage is high, it absorbs reactive power (SVC inductive).

Control is achieved by variation of the firing angle of the thyristors .

It is prudent to keep reactive power flows to a minimum in order to allow the lines to carry more active power. 11

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In the electrical trade the capacitor bank is used for power factor correction.

A bank of capacitor is connected across the load.

Since the capacitor takes leading reactive power overall reactive power taken from the source decreases & system power factor improves.

The capacitive reactance is used to offset the inductive reactance caused by inductive loads (motors). Motor loads can cause the power factor to drop to .8 or lower and for this the customer is penalized by an extra service charge. The goal is to have a power factor level above .9. where there is no surcharge from the power supply authority. The cost of installing a capacitor bank is soon paid off from the absence of the surcharge. 13

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A 3-phase synchronous motor, when over excited, works as a synchronous condenser or a capacitor.

It gives dynamic power-factor correction over a wide range of its excitation.

When under excited , it operates at a lagging pf and therefore absorbs reactive power from the bus . When over excited, a synchronous , motor works at a leading pf and therefore acts as a generator of reactive power and therefore behaves like a capacitor

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The Static Synchronous Compensator (STATCOM) is a shunt device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow and improve transient stability on power grids .

The STATCOM regulates voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system. When system voltage is low, the STATCOM generates reactive power (STATCOM capacitive).

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The STATCOM basically performs the same function as static var compensators but with some advantages like

long distance transmission systems, power substations and heavy

industries where voltage stability is the primary concern.

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Power factor can be measured by using power factor meter which is well known in power industry.

A direct reading power factor meter can be made with a moving coil meter of the electrodynamic type, carrying two perpendicular coils on the moving part of the instrument. The field of the instrument is energized by the circuit current flow. The two moving coils, A and B, are connected in parallel with the circuit load. One coil, A, will be connected through a resistor and the second coil, B, through an inductor, so that the current in coil B is delayed with respect to current in A.

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At unity power factor, the current in A is in phase with the circuit current, and coil A provides maximum torque, driving the instrument pointer toward the 1.0 mark on the scale. At zero power factor, the current in coil B is in phase with circuit current, and coil B provides torque to drive the pointer towards 0.

At intermediate values of power factor, the torques provided by the two coils add and the pointer takes up intermediate positions.

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Power factor can also be calculated by installing watt meter along with the Ammeter and volt meter by using the power factor basic formula.

Power factor=Actual Power/ Apparent power

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Eliminate Power Factor Penalties Increase System Capacity Reduce Line Losses in distribution systems Conserve Energy Improve voltage stability Less total plant KVA for the same KW working

power Improved voltage regulation due to reduced line

voltage drop

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Reduction in size of transformers, cables and switchgear in new installations.

Increase equipment life

Save on utility cost

Enhance equipment operation by improving voltage

Improve energy efficiency

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Utility companies in many areas include a penalty charge in the electrical rate for low power factor. The installation of power factor capacitors on the user's electrical distribution system eliminates the necessity of paying premium rates to the utility company for poor power factor.

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By adding capacitors to the system, the power factor is improved and the KW capacity of the system is increased.

For example, a 1,000 KVA transformer with a 70% power factor provides 700 KW of power to the main bus. With the installation of capacitors so that the power factor is improved, say, to 90%, the KW capacity of the system is increased to 900 KW.

When a system power factor is improved, the amount of reactive current flowing is lowered thus reducing transformer and distribution circuit loads.

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Increases heating losses in the transformers and distribution equipments.

Reduce plant life. Unstabilise voltage levels. Increase power losses. Upgrade costly equipments. Decrease energy efficiency. Increase electricity costs by paying power

factor surcharges.

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By observing all aspects of the power factor ,it is clear that power factor is the most significant part for the utility of the Company as well as for the consumer. Company get rid of the power losses while the consumer free from low power factor penalty charges.

By installing suitably sized power capacitors into the circuit the Power Factor is improved and the value becomes nearer to 1 thus minimising line losses and improving the efficiency of a plant.

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