governing system.ppt
DESCRIPTION
governing system basicsTRANSCRIPT
GOVERNING SYSTEM
GOVERNORQuality of power depends on:FrequencyVoltage
These need to be regulated properly for stable and accurate output for good performance.
Governing system is used for regulating frequency and power output.
GOVERNOR
Hydraulic turbine governor is used for Hydraulic turbine governor is used for
controlling the guide vanes by detecting controlling the guide vanes by detecting
turbine speed & its guide vane opening in turbine speed & its guide vane opening in
order to keep turbine speed stable or to order to keep turbine speed stable or to
regulate its output.regulate its output.
The performance of the governor dominates The performance of the governor dominates
the controllability of the power plant and the controllability of the power plant and
quality of an electrical power produced .quality of an electrical power produced .
MAIN COMPONENTS OF GOVERNING SYSTEM
Speed Signal
Electrical/Electronic Governor
Hydro-Mechanical Cabinet
G.V.Position Feedback Device
Oil Pressure Unit
Servomotors
SPEED SENSING DEVICES
TYPE
PMG
Toothed Wheel (capacitor type probe)
PT Voltage (frequency detection)
Over Speed Detection (mechanical)
SPEED SENSING BY TOOTHED WHEEL SENSOR
Governor is a speed sensing type,sensitive to speed deviation from a set value of speed.The speed signal is generally produced with a turbine shaft mounted toothed wheel and magnetic pickup.
f = n * p / 60, f = frequency of sensor output n = speed of the toothed wheel( r.p.m) p = no. of teeth on the toothed wheel The signal is processed in frequency
to voltage converter
USE OF SPEED SENSING
Speed Control
Power Control
Braking
Field Breaker Control
Over Speed Tripping
Machine Standstill Signal
LVDT – Linear Voltage Differential Transducer
FEEDBACK MECHANISM
To Servo Motor
Displacement of Transducer
Supply
W C
W
W
ELECTRO HYDRAULIC GOVERNOR
POWER SUPPLY UNIT SPEED SIGNAL MODULE SPEED RELAYS SPEED SETTING POWER SETTING PERMANENT SPEED DROOP TEMPORARY SPEED DROOP AMPLIFIERS
O/P Setting Command
Freq. Ref. Setting P. Droop
SettingSummationAmplifier
BoosterAmplifier
E. Hydro.Transducer
Hydro.Amplifier
From OPU
ServoMotor
Permanent Droop Signal
Freq. Signal
Comparator
-
-
PERMANENT DROOP
Gate OpeningFeedback
Permanent Droop Setting 10%
0 50 HZ45 HZ Freq.
100%
Pow
er
Permanent Droop Setting 5%
0 Freq.
Pow
er
100%
50 HZ47.5 HZ
O/P Setting Command
Freq. Signal
Gate Opening Feedback
Differentiator Adjustable Setting of Time & %
SummationAmplifier
Temp.Droop Signal
Temporary Droop Signal is a damping signal. It
opposes transiently gate movement and thus
provides main stablisation to speed control loop.
TEMPORARY DROOP SIGNAL
Freq. Ref. Setting
Comparator
-
-
DEAD BAND UNIT Prevents Governor action over a
selected band of speed
M/c will maintain constant power for system frequency variation of (Fn ± DB)Hz Fn - Normal Frequency
DB - Selected Dead Band
ZERO SPEED DETECTOR
It is to disengage the generator brakes when
turbine comes to almost dead halt
It gives signal when speed drops out to less
than 0.1 Hz
GOVERNOR PANEL FOR CONTROL OF SPEED AND GOVERNOR PANEL FOR CONTROL OF SPEED AND POWER OF THE POWER OF THE MACHINEMACHINE
GOVERNOR
INDICATION FOR1 SPEED2 GATE POSITION3 SPEED SETTING4 OUTPUT SETTING5 EHT CURRENT
GATE OPEN/CLOSECONTROL
SENSING OF SPEED RELAYS
4 EXCITATION CONTROL3 PROTECTION2 BRAKE
5 H.S.LUB.START
1 ZERO SPEED
(PMG.SSG.PT.)
GATE POSITIONFEED BACK
COMMANDSETTINGOUTPUT
POSITIONCOMMANDSPEED SETTING
COMMANDOPEN LIMITGATE
GOVERNORO
UT
UTP
COMMANDSTART(M/C)
SPEED SIGNALSTATUS
POSITIONC.B.
COMMAND
(M/C)STOP
Speed/Freq. Sensor
Temp. Droop
Commands
AmplifierDistributing
Valve
Gate Servomotor
PermanentDroop
GateOr
Needle
Turbine
Gen.
GOVERNING SYSTEM
PTVoltage PMG/
TWG
GATE POSITION SWITCH
(MASTER CONTROLLER)
1. Gate Closed Position
2. M/C Start Gate Open Position
3. Controlled Action Shutdown Gate Position
4. Full Gate Open Position
CONTROL AVAILABLE IN GOVERNOR
1. Auto/Mannual Selector Switch
2. Local / Remote Selector Switch
3. Increase/Decrease
Power/Frequency
These Buttons/Switch Changes
- Frequency Reference 0 - 100%
- 45 HZ 50 HZ 55 HZ
- 0 50 % 100 %
- Output Reference 0 - 100%
0 No Power
100% Full Power
4. Increase/Decrease
Guide Vane Limiter 0 – 100%
- Electronic
- Mechanical
5. Droop Characteristic
One of two Permanent Droop curves may be
selected.
However set values of curves has to be altered
by software package
HYDRO MECHANICAL CABINET
AUTO/MANUAL SWITCH GATE POSITION LIMITER GUIDE VANE POSITION INDICATOR SPEED INDICATOR BALANCE INDICATOR PRESSURE INDICATOR ELECTRO HYDRAULIC TRANSDUCER EMERGENCY SLIDE VALVE GUIDE VANE OPENING FEEDBACK
SPEED SIGNAL GENERAROR
GENERATOR TURBINE
TURBINE WICKWT GATE
SPEED SENSOR
PILOT SERVO VALVE
MAIN VALVE
TURBINE SERVOMOT0R
OIL SUMP
PRESSURE TANK 40 Kg/CM2
MECH. CONNECTION ELECT. GOV
HYDRAULIC POWERTURBINE INFLOW
SPEED CONTROL BY SERVOMECHANISM
RETURN OIL/LEAKAGE
OIL PUMP
Start Pos. 2
Time
Start Pos. 1
Start Input
G.V. Opening
Limiter
No Load Position
G. V. Lock to Service Position
Loa
ding
FACTORS AFFECTING GOVERNING PERFORMANCE
1. Unit acceleration time (Tm)This is the time in seconds to accelerate the unit from standstill to normal speed. It is a measure of sensibility of the unit on load changes.Given by:
Tm = WR2n2/(9.08*104*N)WR2= flywheel effect of generation in kg-m2
n= Rotational speedN= Turbine capacity in kW
2. Inertia of water mass (TW)
Higher inertia of water masses leads to unstable governing. Where the water conductor system is long, Surge tanks are provided.
Given by,
TW= ∑ LV/(g*h)
Where,
L= length of water conductor in m
V= velocity in m/sec.
H= Rated head in m
3. SPEED RISE:
Depends upon guide vanes/ Deflector minimum closing time.
4. PRESSURE RISE:
Depends upon guide vane/ needle servomotor minimum closing time.
OIL PRESSURE UNIT OIL SUMP WITH LEVEL INDICATOR OIL PRESSURE
PUMP-MAIN/STANDBY PRESSURE RECEIVER WITH
PRESSURE SWITCH, LEVEL SWITCH
MACHINE IS TRIPPED FOR VERY LOW PRESSURE AND VERY LOW LEVEL AND FOR LOW LEVEL/PRESSURE ALARM IS PROVIDED
OIL SUMPTANK
LEVELRELAY
OIL PUMPS
MOTOR STARTER
PRESSURERELAY
PRESSURERECEIVER
HP COMPRESSED
AIR
ELECT.HYDRAULICGOVERNOR
G. V.SERVOMOTOR
GUIDEVANESOLU
OIL PUMPING UNIT
LEVELRELAY
CONTROL OF O P U
Pump Motors are controlled in Auto Mode by the following Pressure switches:
Pressure Normal Stop both pumps Pressure switch to start pump – main Pressure switches for M/c control Pressure Normal – Unit ready to start
condition Pressure Low - Alarm Pressure Very Low - Emergency shut
down
OIL LEVEL SWITCHES
Sump oil level normal
Sump oil level low
Pressure receiver oil level normal
Pressure receiver oil level low (Pumps
are not working)
Pressure Receiver oil level high (Air
admission is required)
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