Blocked nozzle detection and remedial method and system

1. A method for controlling a stuck nozzle system installed between first and second turbines connected in series to a compressor, the method comprising:

determining whether the nozzle system is stuck;

instructing the first turbine to increase a minimum reference speed when the nozzle system is stuck;

verifying whether the nozzle system continues to be stuck;

instructing the compressor to increase an inlet bleed heat (IBH) flow from a current value to a maximum value when the nozzle system is stuck;

verifying whether the nozzle system continues to be stuck; and

instructing the compressor to increase an inlet guide vanes (IGV) angle from a current value to a maximum value when the nozzle system is stuck.

2. The method of claim 1 , further comprising:

increasing the minimum speed reference of the first turbine, increasing the IBH flow and increasing the IGV angle in this sequence.

3. The method of claim 2 , further comprising:

stopping the sequence when the nozzle system is not stuck.

4. The method of claim 1 , further comprising:

increasing the minimum speed reference of the first turbine from a current value to a higher value without verifying whether a control of the nozzle system has been regained.

5. The method of claim 4 , wherein the minimum speed reference is about 94% of a nominal value and the increased minimum speed reference is about 98% of the nominal value.

6. The method of claim 1 , further comprising:

increasing incrementally the IBH flow from the current value to the maximum value; and

detecting whether the nozzle system is still stuck between incremental increases of the IGV angle.

7. The method of claim 6 , further comprising:

stopping the incremental increase of the IGV angle when the nozzle system is unstuck.

8. The method of claim 6 , wherein the maximum value is 7% of a maximum flow through the compressor.

9. A system configured to remedy stuck nozzles, the system comprising:

a compressor configured to compress a medium, the compressor including,

an inlet bleed heat (IBH) mechanism that allows part of the compressed medium back to an inlet of the compressor, and

an inlet guide vanes (IGV) mechanism configured to control a medium flow into the inlet of the compressor;

a combustor fluidly connected to the compressor and configured to mix the compressed medium with fuel for generating an exhaust gas after ignition;

first and second turbines connected in series to the combustor;

a nozzle mechanism including the nozzles and configured to adjust a split of enthalpy between the first turbine and the second turbine; and

a controller connected to the first turbine, the IBH mechanism, and the IGV mechanism and configured to increase a minimum speed reference of the first turbine, an IBH flow and an IGV angle to unstuck the nozzle mechanism.

10. A non-transitory computer readable medium including computer executable instructions, wherein the instructions, when executed, implement a method for controlling a stuck nozzle system installed between first and second turbines connected in series to a compressor, the method comprising:

determining whether the nozzle system is stuck;

instructing the first turbine to increase a minimum speed reference when the nozzle system is stuck;

verifying whether the nozzle system continues to be stuck;

instructing the compressor to increase an inlet bleed heat (IBH) flow from a current value to a maximum value when the nozzle system is stuck;

verifying whether the nozzle system continues to be stuck; and

instructing the compressor to increase an inlet guide vanes (IGV) angle from a current value to a maximum value when the nozzle system is stuck.