Load Frequency Control Slides _ Part One

Load Frequency COntrol 1

1. Load Frequency Control

2. Power System
•The power system needs to supply
•Active Power
•Reactive Power

3. Importance of Frequency

4. Power System
•Constant frequency is to be maintained for the following functions:
•AC motors should require constant frequency supply so as to maintain speed
constant.
•In continuous process industry, it affects the operation of the process itself.
•For synchronous operation of various units in the power system network, it is
necessary to maintain frequency constant.
•Frequency affects the amount of power transmitted through interconnecting lines.
•Electrical clocks will lose or gain time if they are driven by synchronous motors,
and the accuracy of the clocks depends on frequency and also the integral of this
frequency error is loss or gain of time by electric clocks.

5. LOAD FREQUENCY CONTROL
•Basiccontrolmechanism.
•Variationinloaddemandonageneratingunit,thereismomentarilyan
occurrenceofunbalancebetweenreal-powerinputandoutput.
•Difference is supplied by energy stored in rotating parts of the unit.
•Kinetic energy of any unit is given by
•If KEreduces, ω decreases; then the speed falls, hence the frequency reduces.
•Δfissensedandthroughaspeed-governorsystem,itisfedbacktocontrolthe
positionoftheinletvalveoftheprimemover,whichisconnectedtothe
generatingunit.
•Hence,itcanbestatedthatthefrequencyvariationisdependentonthereal-
powerbalanceofthesystem.