TWO-SHAFT GAS TURBINE CONTROL SYSTEM

• US 3,638,422 A
• Filed: 06/26/1970
• Issued: 02/01/1972
• Est. Priority Date: 06/26/1970
• Status: Expired due to Term

• Current Assignee: Arne Loft, Daniel Johnson
• Original Assignee: Arne Loft, Daniel Johnson
• Inventors: Loft, Arne, Johnson, Daniel
• Primary Examiner(s): Gordon, Clarence B.
• Application Number:
  US05/050,286
• Time in Patent Office: 585 Days
• Field of Search: 60/39.28 416/27,30
• US Class Current: 60/39.281
• CPC Class Codes: F02C 9/54 by throttling the working fluid, by adjusting vanes

Abstract

In a two-shaft gas turbine having an adjustable nozzle between the compressor high-pressure turbine and the load turbine, a control system is provided in which a biasing signal is added to the fuel temperature control increasing its base reference so that on an increase in called for speed or load the gas turbine is able to dynamically respond in an improved manner. The steadystate temperature limits are exceeded transiently without damage to the gas turbine until the system returns to its new steadystate condition. Also provided for the two-shaft gas turbine is an acceleration limiting control whereby the overall gas turbine is allowed to accelerate at the maximum allowable value of either of the two shafts. Further provision is made for a blowoff valve control whereby excess energy from a regenerator is diverted from the turbines so that the speed and load control will remain in command, thus preventing overspeed conditions and/or subsequent shutdown.

Claims

1. In a control system for a gas turbine power plant having a compressor high-pressure turbine unit and a load turbine unit, the compressor high-pressure turbine unit discharging motive fluid through an adjustable nozzle to the load turbine unit, said units being mechanically independent and also having servo means to control fuel flow to the combustion chambers in accordance with a fuel control signal, the combination comprising:

a plurality of closed loop control means, each arranged to supply a respective fuel control signal for controlling a respective operating condition, at least one of said control means being continuously responsive to a temperature condition of the gas turbine and comparing said condition to a temperature setting, gating means connected to be responsive to said loop control means and enabling only one of said fuel control signals representing the least fuel to control said fuel flow servo means, nozzle control means responsive to shaft speed and temperature signals such that the adjustable nozzle is normally positioned to hold the exhaust temperature substantially constant over a portion of the load range, and biasing means connected to augment the temperature setting of the closed loop control means responsive to temperature so that when additional load is called for, fuel can be added quickly allowing temperature to increase to the new temperature limit.

2. The control system according to claim 1 in which the biasing means is comprised of means to compare an actual compressor high-pressure turbine speed with a substantially 100 percent speed reference and apply the resulting signal to the loop control means responsive to temperature.

3. The control system according to claim 2 further comprising circuit opening means for eliminating the biasing means from circuit below a minimum shaft speed.

4. The control system according to claim 1 in which at least one of the closed loop control means is responsive to load turbine speed and includes means to divert excess energy from the turbine, with the energy-diverting means being responsive to a signal that represents the difference between actual load turbine speed and its desired speed.

5. The control system according to claim 4 in which the energy-diverting means includes the adjustable nozzle and further having valve means connected so as to vent compressor air before it enters the combustion chamber, said energy-diverting means arranged and adapted to open first the adjustable nozzle and then the valve means.

6. The control system according to claim 1 in which at least two of said closed loop control means are responsive to acceleration of said units and including first means to compare the compressor high-pressure unit acceleration with a first acceleration with a second acceleration reference and providing respective acceleration limiting fuel control signals to said gating means.