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 Headlines

Hydro-Quebec agrees to buy NB Power for C$4.75 billion (Oct 29, 2009)
State-owned Hydro-Quebec, the world’s largest producer of hydropower, will purchase most of the assets of New Brunswick Power in a C$4.75 billion (US$4.45 billion) deal that will lower rates for New Brunswick customers.
NASCAR attraction will be ready for HydroVision International 2010 (Oct 26, 2009)
In addition to networking with hundreds of hydropower professionals, delegates at HydroVision International 2010 can pay a visit to the NASCAR Hall of Fame.
U.S. hydropower consumption increases 5.1 percent (Oct 23, 2009)
During the first seven months of 2009, hydropower consumption in the United States was up 5.1 percent compared with the same period in 2008, according to a report by the Energy Information Administration, the statistical arm of the U.S. Department of Energy.
Exhibition space still available for HydroVision 2010 (Oct 16, 2009)
HydroVision International 2010 is nine months away, but 50 percent of the exhibit hall is already booked as vendors secure a place at the hydropower industry’s biggest conference and trade show.
NHA to release study on job creation (Oct 12, 2009)
During a press conference Oct. 13, the National Hydropower Association will release a comprehensive study indicating the number of jobs the hydropower industry is poised to create in the United States.
Graham wins registration to HydroVision International, online registration now open (Oct 9, 2009)
Wayne Graham, a hydraulic engineer for the U.S. Bureau of Reclamation, will be one of hundreds of hydropower professionals attending HydroVision International 2010 in Charlotte, N.C.
Hydropower allocation triggers New York plant expansion (Oct 7, 2009)
The New York Power Authority has agreed to provide four MW of low-cost hydropower to Metaullics Systems, a move that could create as many as 48 new jobs at the company’s plant in Sanborn, N.Y.
TransAlta, Canadian Hydro agree to buyout offer (Oct 5, 2009)
TransAlta Corp., after increasing its bid 15 percent, has reached an agreement to buy Canadian Hydro Developers Inc. for C$755 million (US$703 million).
Report assigns blame for Russian accident (Oct 5, 2009)
A report by a government watchdog on the Aug. 17 explosion that paralyzed Russia's Sayano-Shushenskaya hydroelectric power plant, claiming 75 lives, says former chief executive of national electricity company Unified Energy Systems (UES) Anatoly Chubais is partially to blame for the conditions that led to the tragedy.
For more go to hydroworld.com
Source: Hydroworld.com