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1. Presented by
22EE011 – DHANUSH KUMAR B
NANDHA ENGINEERING COLLEGE, AUTONOMOUS,
ERODE -52
DEPARTMENT OF ELECTRICALAND ELECTRONICS
ENGINEERING
22EEX14 - POWER SYSTEM OPERATION &
CONTROL
Faculty-in-charge
Mr. B. Ramraj AP/EEE
Seminar On Speed Governing Mechanism

2. Turbine Speed Governing Mechanism
• The speed governor is the main primary tool for the
load frequency control (LFC).
• Figure shows a schematic arrangement of a speed
governing system used on steam turbines to control the
output of the generator to maintain constant frequency.
• The speed governing system consists of the following
parts.

3. 3
Speed changer
Lower
Raiser
XA
XB
XC
XD
XE
Speed Governor
Pilot valve
High
pressure
oil
To Turbine
Steam
Steam valve
Main piston
Hydraulic amplifier
l1
l2 l3
l4
Fundamentals of Speed Governing System

4. 4
The system consists of following components
1. Fly ball governor
2. Hydraulic amplifier
3. Linkage mechanism
4. Speed changer
Fly ball speed governor:
5. This is the heart of the system which senses the change in speed of the
system.
6. As the speed increases, the fly ball moves outwards and the point B on
linkage mechanism moves downwards. The reverse happens when the speed
decreases.

5. 5
Hydraulic amplifier
1. It consists of pilot value and main piston.
2. Low power level pilot valve movement is converted into high power level
pilot valve movement.
3. This is necessary in order to open or close the steam value against high
pressure system.
Linkage mechanism
1. ABC is a rigid link pivoted at B and CDE is another rigid Link pivoted at D.
2. This link mechanism provides a movement of control valve in proportion to
the change in speed.
Speed changer:
3. It provides a steady state power output setting for the turbine.
4. Its downward movement opens the upper pilot valve so that more steam is
admitted to the turbine under steady conditions (hence more steady power
output).
5. The reverse happens for upward movement of speed changer.

6. Derivation:

8. 8
Speed Governor Model
The governor compensates for changes in the shaft speed
1. Changes in load will eventually lead to a change in shaft speed.
2. Change in shaft speed tends to change in system frequency.

9. 9
Turbine model
1. The prime mover driving a generator unit may be a steam turbine or a hydro
turbine.
2. The models for the prime mover must take account of the steam supply and
boiler control system characteristics in the case of steam turbine on the
penstock for a hydro turbine.
3. The dynamic response of steam turbine in terms of changes in generator power
output ΔPG to change in steam valve opening ΔXE.

10. Generator load or Power system model
1. To develop the mathematical model of an isolated generator,
which is only supplying local load and is not supplying power to
another area,
2. Suppose there is a real load change of ΔPD.
3. Due to the action of the turbine controllers, the generator increases
its output by an amount ΔPG.
4. The net surplus power (ΔPG - ΔPD) will be absorbed by the system
in two ways.
i. By increasing the kinetic energy in the rotor.
ii. As frequency changes, the motor load changes being
sensitive to speed.

11. Model of Load frequency control of single area