Hydro Generator- Part 3

Out-puts from a Generator - Governors

•

• •Governor ensures frequency at a set value by increasing / decreasing the fuel input
  
  Two types of Governors :
  Pneumatic : Fuel flow is controlled by valve position control. Control Input : DC Voltage

          Electronic : Fuel flow is controlled by a total servo mechanism. Control input : DC Voltage pulses 

 

Out-puts from a Generator - Voltage

• •Voltage is induced in the stator winding
•  Terminal voltage depends upon :

1.   No. of conductors in series per winding
2.   Speed at which magnetic field cuts the winding
3.   Strength of the magnetic field
   

 Voltage Control

• •Nominal Voltage = 415 V, 11 kV 
• Voltage can vary due to load fluctuations 
• Terminal voltage is controlled by

varying the Strength of magnetic field

          = varying the current through the field coil
          = varying the voltage applied to the field coil (Exciter control)

 

Typical Exciter

 

Read more in coming posts... 

Hydro Generator- Part 2

Generator components

Prime Mover

• Source of mechanical power for relative motion
• Two classes of Prime movers :

                            High Speed : Steam & Gas Turbines
                            Low Speed : IC engines, Water turbines and DC motors

• Type of prime mover plays an important role in a generator installation. Many characteristics of alternator and its construction depend upon Speed at which the rotor is turned. 

 Rotors

• Two types are used in rotating field alternators

            - Turbine driven rotor ( used where prime mover is a high speed turbine)

            - salient pole rotor( used with low speed prime movers)

Stator

Many types based on

                   - Power out put
                   - Voltage output
                  - Type of cooling
                  - Number of phases

Simplified schematic of 3 ph. Stator

• Three single phase windings displaced by 120 degrees
• Star or Delta connection
• Neutral may or may not be brought out
• No. of terminals can be 3,4, or 6

Out-puts from a Generator

• Three phase ac power at :

                 -Rated Voltage
                 -Rated Frequency

Common Ratings

• Small Generators : 25 kVA to 300 kVA
• Medium Size Generators : 500 kVA to 1 MVA
• Large size Generators : 1 MVA to 25 MVA
• Power Plant Generators: 110 MW to 500 MW

Frequency

• Frequency depends up on the Speed of Rotation ( direct proportion)
• F = PN / 120 where F = frequency in Hz, P = No. of poles, N = speed of rotation in RPM, ( 120 is a constant to convert minutes to seconds and poles to pole pairs)
• Nominal frequency = 50/60 Hz
• Generator frequency can vary due to load fluctuations
• Frequency Regulation is mainly by adjusting the speed
• speed is controlled by varying the fuel input to the prime mover ( Governor control)

Read more in coming posts...

Hydro Generator- Part 1

GENERATOR BASICS

Generator Structure

• Generator is a machine which converts Mechanical energy into Electrical energy
• Magnetic Induction Principle
• An emf is induced in a coil whenever
• a coil cuts through a magnetic field
• a magnetic field cuts through a coil
• emf induction is due to relative motion between two parts ( coil & magnetic field)
• Relative motion is by Rotation
• Two mechanical parts :
• Field - Part which produces magnetism (Rotor)
• Armature – part where emf is induced (Stator)

Generator components

• Prime Mover
• Rotor (Exciter)
• Stator

 

Read more in coming posts...

Advantage of Horizontal Machines

Advantage in Design:

• Simple in Design (Standardized size available)
• Hydraulic path is simpler (No distributor for tubular)
• No Complicated parts
• Even distribution of load on foundation (as turbine load come at different place and generator load at different place etc.,)

Advantage in Efficiency:

• Better efficiency for lesser MW project (as flow is straight and Hydraulic passage is of lesser restriction to flow.

Advantage in Layout:

• Simpler Layout (all auxiliary equipment can be placed in one floor and close to main generating equipment - Better coordination by operator)
• Entire equipment is directly under crane hook making approach very easy for erection, maintenance - Reduce down time during maintenance.

Advantage in Supply:

• As design is simpler and standardized, quicker delivery period.
• All equipment can be supplied in 6 to 12 months.
• Saving in delivery period of the order of about 6 months

Advantage in Erection:

• Erection time is less (as equipment distributed on one floor)
• Machine (turbine as well as generator) can be fully assembled in shop / service bay and lowered to foundations.
• Results in shorter erection & commissioning time (3 to 6 months)

Advantage in Operation:

• Easier control and vigil (operator sitting in control room can see all the equipments and can take preventive shutdown, if required)
• No skilled personnel are required. As no complex parts are involved thus, easy to understand the parts and system.

Advantage in Maintenance:

• Simple design; hence availability of spares is easy.
• Easy Maintenance; All equipment are exposed in Horizontal formation thus can be maintained independently like turbine & Generator independently.
• Also the Turbine is exposed (not fully buried in concrete) thus inspection, repair, maintenance etc., is easier.

                                                             Horr. Francis Arrangement

National Hydro Power Association

This post is for making visitors of this page aware of National Hydro Power Association annual conference(April 26-28, 2010). Extract from the NHA website.

Impact the future of the hydropower industry by joining hundreds of colleagues at the 2010 National Hydropower Association Annual Conference, April 26-28 at the Capital Hilton Hotel in Washington D.C. This dynamic three-day event brings together industry leaders, state and federal regulatory officials and key legislative staff to discuss technology, policy and future development options for the hydropower sector.

BENEFITS OF ATTENDANCE

- In-depth educational sessions exploring hot topics in technology, policy and future development
- Networking opportunities with hundreds of colleagues
- Visits to Capitol Hill
- Opportunities to exchange ideas, solutions and new approaches to new and existing challenges
- Access to industry resources and affiliates
- And more

WHO SHOULD ATTEND

- NHA members
- Hydro policy makers
- Hydro industry leaders and organizations
- Public utilities
- Investor-owned utilities
- Independent power producers
- Equipment manufacturers
- Environment and engineering consultants and attorneys
- Advocates of hydropower in the U.S.
- Project managers
- Service contractors
- Government and NGO representatives

Professional Development Hours

National Hydropower Association conference attendees registered as Full Conference Delegates are eligible to receive 12 Professional Development hours. Instructions on how to access your certificate of completion will be automatically emailed to all Conference Delegates following the 2010 event.

Conference registration includes:

All program sessions
President's luncheon Tuesday afternoon
Hospitality receptions on Monday and Tuesday evenings
Refreshment breaks
All conference materials
12 professional development hours (PDHs)

For more info visit NHA website

Latest Trends in Hydro Turbines

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Latest Trends in Hydro Turbines -

Horizontal Vs Vertical Turbine

Advantage of Horizontal Machines

Advantage in Design:
-Simple in Design (Standardized size available)
-Hydraulic path is simpler (No distributor for tubular)
-No Complicated parts
-Even distribution of load on foundation (as turbine load come at different place and generator load at different place etc.,)

Advantage in Efficiency:
-Better efficiency for lesser MW project (as flow is straight and Hydraulic  passage is of lesser restriction to flow) 

Advantage in Layout:

-Simpler Layout (all auxiliary equipment can be placed in one floor and close to main generating equipment - Better coordination by operator)

-Entire equipment is directly under crane hook making approach very easy for erection, maintenance Reduce down time during maintenance.

Advantage in Supply:

-As design is simpler and standardized, quicker delivery period.

-All equipment can be supplied in 6 to 12 months.

-Saving in delivery period of the order of about 6 months

Advantage in Erection:
-Erection time is less (as equipment distributed on one floor)
-Machine (turbine as well as generator) can be fully assembled in shop / service bay and lowered to foundations.
-Results in shorter erection & commissioning time (3 to 6 months)

Advantage in Operation:
-Easier control and vigil (operator sitting in control room can see all the equipments and can take preventive shutdown, if required)
-No skilled personnel are required. As no complex parts are involved thus, easy to understand the parts and system

Advantage in Maintenance:
-Simple design; hence availability of spares is easy.
-Easy Maintenance; All equipment are exposed in Horizontal formation thus can be maintained independently like turbine & Generator independently.
-Also the Turbine is exposed (not fully buried in concrete) thus inspection, repair, maintenance etc., is easier.


Horizontal Francis Turbine