Abstract:
The project is designed to minimize penalty for industrial units by using
automatic power factor correction unit. Power factor is defined as the ratio
of real power to apparent power. This definition is often mathematically
represented as KW/KVA, where the numerator is the active (real) power and
the denominator is the (active + reactive) or apparent power. Reactive power
is the non working power generated by the magnetic and inductive loads, to
generate magnetic flux. The increase in reactive power increases the
apparent power, so the power factor also decreases. Having low power
factor, the industry needs more energy to meet its demand, so the efficiency
decreases.
In this proposed system the time lag between the zero voltage pulse and zero
current pulse duly generated by suitable operational amplifier circuits in
comparator mode are fed to two interrupt pins of the microcontroller. It
displays the time lag between the current and voltage on an LCD. The
program takes over to actuate appropriate number of relays from its output
to bring shunt capacitors into the load circuit to get the power factor till it
reaches near unity. The microcontroller used in the project belongs to 8051
family.
Further the project can be enhanced by using thyristor control switches
instead of relay control to avoid contact pitting often encountered by
switching of capacitors due to high in rush current.
