GOVERNING SYSTEM.ppt

Quality of power depends on: Frequency

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Voltage

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These need to be regulated properly for  stable and accurate output for good performance. Governing system is used for regulating frequency and power output.

Quality of power depends on: Frequency



Voltage



These need to be regulated properly for  stable and accurate output for good performance. Governing system is used for regulating frequency and power output.

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Hydraulic turbine governor is used for  controlling the guide vanes by detecting turbine speed & its guide vane opening in order to keep turbine speed stable or  to regulate its output.

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The

performance

dominates

the

of

the

controllability

governor  of

the

power plant and quality of an electrical power produced .

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Speed Signal

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Electrical/Electronic Governor 

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Hydro-Mechanical Cabinet

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G.V.Position Feedback Device

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Oil Pressure Unit

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Servomotors

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TYPE

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PMG

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Toothed Wheel (capacitor type probe)

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PT Voltage (frequency detection)

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Over Speed Detection (mechanical)

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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,

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f = frequency of sensor output

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n = speed of the toothed wheel( r.p.m)

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p = no. of teeth on the toothed wheel

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The signal is processed in frequency to voltage converter 

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Speed Control

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Power Control

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Braking

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Field Breaker Control

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Over Speed Tripping

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Machine Standstill Signal

To Servo Motor Displacement of Transducer      

Supply

W

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W

C

     

W

LVDT  –  Linear Voltage Differential Transducer

FEEDBACK MECHANISM

POWER SUPPLY UNIT  SPEED SIGNAL MODULE  SPEED RELAYS  SPEED SETTING  POWER SETTING  PERMANENT SPEED DROOP  TEMPORARY SPEED DROOP  AMPLIFIERS 

Freq. Signal Freq. Ref. Setting O/P Setting Command

Comparator

-

P. Droop Setting

Permanent Droop Signal Summation Amplifier

Booster Amplifier

E. Hydro. Transducer Gate Opening Feedback 

From OPU Hydro. Amplifier

Servo Motor

PERMANENT DROOP

100%

100%

  r   e   w   o    P

  r   e   w   o    P

0 45 HZ

Freq.

50 HZ

Permanent Droop Setting 10%

0 47.5 HZ

Freq.

50 HZ

Permanent Droop Setting 5%

TEMPORARY DROOP SIGNAL Freq. Signal Freq. Ref. Setting O/P Setting Command

Comparator

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Differentiator Adjustable Setting of Time & %

Temp. Droop Signal

Summation Amplifier

Gate Opening Feedback 

Temporary Droop Signal is a damping signal. It opposes transiently gate movement and thus provides main stablisation to speed control loop.

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Prevents Governor action over a selected band of speed

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M/c will maintain constant power for  system frequency variation of (Fn

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It is to disengage the generator brakes when turbine comes to almost dead halt

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It gives signal when speed drops out to less than 0.1 Hz

GOVERNOR PANEL FOR CONTROL OF SPEED AND POWER OF THE MACHINE

STATUS COMMAND COMMAND START STOP SPEED SIGNAL C.B. POSITION (M/C) (M/C) (PMG.SSG.PT.)

GATE POSITION FEED BACK

GOVERNOR

O U T P U T

SPEED SETTING OUTPUT GATE COMMAND SETTING OPEN LIMIT POSITION COMMAND COMMAND

GOVERNOR

INDICATION FOR 1 2 3 4 5

SPEED GATE POSITION SPEED SETTING OUTPUT SETTING EHT CURRENT

GATE OPEN/CLOSE CONTROL SENSING OF SPEED RELAYS 1 2 3 4 5

ZERO SPEED BRAKE PROTECTION EXCITATION CONTROL H.S.LUB.START

Commands

GOVERNING SYSTEM Gate Servomotor

Temp. Droop Amplifier Permanent Droop

Distributing Valve

Gate Or Needle

Turbine Speed/Freq. Sensor Gen. PT Voltage

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

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Frequency Reference

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45 HZ

50 HZ 55 HZ

-

0

50 % 100 %

-

Output Reference 0

No Power

0 - 100%

0 - 100%

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

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AUTO/MANUAL SWITCH

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GATE POSITION LIMITER

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GUIDE VANE POSITION INDICATOR

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SPEED INDICATOR

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BALANCE INDICATOR

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PRESSURE INDICATOR

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ELECTRO HYDRAULIC TRANSDUCER

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EMERGENCY SLIDE VALVE

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GUIDE VANE OPENING FEEDBACK

SPEED CONTROL BY SERVOMECHANISM

SPEED SIGNAL GENERAROR 

SPEED SENSOR 

MECH. CONNECTION

ELECT. GOV

GENERATOR  PILOT SERVO VALVE

TURBINE

TURBINE INFLOW

TURBINE WICKWT GATE

HYDRAULIC POWER 

TURBINE SERVOMOT0R 

MAIN VALVE

RETURN OIL/LEAKAGE PRESSURE TANK  40

Kg/CM2

OIL PUM P

OIL SUMP

G.V. Opening

Limiter

Start Pos. 1 Start Pos. 2 No Load Position G. V. Lock to Service Position

Time Start Input

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 speed N= 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.

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OIL SUMP WITH LEVEL INDICATOR

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OIL PRESSURE MAIN/STANDBY

PUMP-

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PRESSURE PRESSURE SWITCH

WITH LEVEL

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MACHINE IS TRIPPED FOR VERY LOW PRESSURE AND VERY LOW LEVEL AND FOR LOW LEVEL/PRESSURE ALARM IS PROVIDED

RECEIVER SWITCH,

LEVEL RELAY

OIL SUMP TANK 

MOTOR  STARTER 

OIL PUMPS

PRESSURE RELAY

PRESSURE RECEIVER 

LEVEL RELAY

HP COMPRESSED AIR 

ELECT. HYDRAULIC GOVERNOR 

OLU

G. V. SERVOMOTOR 

OIL PUMPING UNIT

GUIDE VANES

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 - Emergency shut  Pressure Very Low down

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Sump oil level normal

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Sump oil level low

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Pressure receiver oil level normal

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Pressure receiver oil level low (Pumps are not working)

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Pressure Receiver oil level high (Air  admission is required)