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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