7/31/2019 Governing Basics
1/48
BASICS OF GOVERNING
P K CHAKRABORTY
7/31/2019 Governing Basics
2/48
Functions of Governing System
To control the initial run up and synchronization of themachine
To control the turbine load when running in parallel withother generating sets.
To contain the speed rise within acceptable limits in caseof the unit getting disconnected from the load
To provide protective gears to ensure the safe operationof the turbine
Thus the individual TG governing system imply a need to
withstand a full load rejection safely
provide appropriate contributions to systemfrequency control.
7/31/2019 Governing Basics
3/48
7/31/2019 Governing Basics
4/48
7/31/2019 Governing Basics
5/48
7/31/2019 Governing Basics
6/48
SPRING
DISC
TURBINE
G
E
NE
R
A
T
O
R
CONTROL
VALVE
7/31/2019 Governing Basics
7/48
TURBINE
CONTROL
VALVE
GEN
M M M M
7/31/2019 Governing Basics
8/48
TURBINE
ROTOR
WORM
GEAR
SPRING
FLY WEIGHT
FIXED
FULCRUM
CONTROL
VALVE
SLEEVE
V
0
maxn1
n3
n2
H
7/31/2019 Governing Basics
9/48
8 BAR
2.5 MM 25 NB LINE
DRAIN
7/31/2019 Governing Basics
10/48
7/31/2019 Governing Basics
11/48
7/31/2019 Governing Basics
12/48
7/31/2019 Governing Basics
13/48
7/31/2019 Governing Basics
14/48
7/31/2019 Governing Basics
15/48
7/31/2019 Governing Basics
16/48
7/31/2019 Governing Basics
17/48
7/31/2019 Governing Basics
18/48
7/31/2019 Governing Basics
19/48
7/31/2019 Governing Basics
20/48
7/31/2019 Governing Basics
21/48
7/31/2019 Governing Basics
22/48
7/31/2019 Governing Basics
23/48
7/31/2019 Governing Basics
24/48
7/31/2019 Governing Basics
25/48
7/31/2019 Governing Basics
26/48
7/31/2019 Governing Basics
27/48
7/31/2019 Governing Basics
28/48
7/31/2019 Governing Basics
29/48
7/31/2019 Governing Basics
30/48
7/31/2019 Governing Basics
31/48
TRANSIENT SPEED RISE
7/31/2019 Governing Basics
32/48
TRANSIENT SPEED RISE
INCREASE OF SPEED ON FULL LOAD THROW OFF
7 TO 9 % OF RATED SPEED
RATED SPEED 3000 RPM 3210 TO 3270 RPM
7/31/2019 Governing Basics
33/48
7/31/2019 Governing Basics
34/48
7/31/2019 Governing Basics
35/48
7/31/2019 Governing Basics
36/48
7/31/2019 Governing Basics
37/48
7/31/2019 Governing Basics
38/48
7/31/2019 Governing Basics
39/48
7/31/2019 Governing Basics
40/48
7/31/2019 Governing Basics
41/48
7/31/2019 Governing Basics
42/48
7/31/2019 Governing Basics
43/48
7/31/2019 Governing Basics
44/48
Governing Of Large Reheat MachinesOn reheat machines it is necessary to control not only the hp
valves but also the interceptor (IP) valves because on a fullload rejection the stored steam in the reheater and theassociated pipe lines could be sufficient to overspeed themachine to destruction. The characterstics of the IP valvesare such that they usually remain fully open over thenormal low range of the machine and the governing actionis achieved by throttling of the HP valves. This operatingregime is known as HP governing & is achieved by giving afixed bias to the IP valves.
However, the reheater control valves comes intoaction during certain abnormal conditions like fast loadrejection or low load conditions with excessively highreheater pressure, with the help of over riding controlsprovided by features like load sheding relay, IP trimmingdevice etc.
7/31/2019 Governing Basics
45/48
What is Droop?
% of frequency change ( % of RPMchange) will lead to full travel of
Governing valves or full load change.
5% droop means: 5%*50 Hz= 2.5 Hz
Will change 500MW. In terms of outputtotal change should take place is 100%
7/31/2019 Governing Basics
46/48
7/31/2019 Governing Basics
47/48
7/31/2019 Governing Basics
48/48