Example 07: Open Cycle Gas Turbine (OCGT)

Example 07: Open Cycle Gas Turbine (OCGT)#

Description#

This example demonstrates a standalone open-cycle gas turbine (OCGT) simulation. The example showcases the turbine’s state machine behavior including startup sequences, power ramping, minimum stable load constraints, and shutdown sequences.

For details on OCGT parameters and configuration, see Open Cycle Gas Turbine. For details on the underlying state machine and ramp behavior, see Thermal Component Base.

Scenario#

The simulation runs for 6 hours with 1-minute time steps. A controller commands the turbine through several operating phases. The table below shows both control commands (setpoint changes) and state transitions (responses to commands based on constraints).

Timeline#

Time (min)

Event Type

Setpoint

State

Description

0

Initial

0

OFF (0)

Turbine starts off, time_in_state begins counting

40

Command

→ 100 MW

OFF (0)

Setpoint changes to full power, but min_down_time (60 min) not yet satisfied—turbine remains off

60

State

100 MW

→ HOT STARTING (1)

min_down_time satisfied, turbine begins hot starting sequence

~64

State

100 MW

HOT STARTING (1)

hot_readying_time (~4.2 min) complete, run-up ramp begins

~68

State

100 MW

→ ON (4)

Power reaches P_min (20 MW) after hot_startup_time (~8.2 min), turbine now operational

~76

Ramp

100 MW

ON (4)

Power reaches 100 MW (ramped at 10 MW/min from P_min)

120

Command

→ 50 MW

ON (4)

Setpoint reduced to 50% capacity

~125

Ramp

50 MW

ON (4)

Power reaches 50 MW (ramped down at 10 MW/min)

180

Command

→ 10 MW

ON (4)

Setpoint reduced to 10% (below P_min), power clamped to P_min

~183

Ramp

10 MW

ON (4)

Power reaches P_min (20 MW), cannot go lower

210

Command

→ 100 MW

ON (4)

Setpoint increased to full power

~218

Ramp

100 MW

ON (4)

Power reaches 100 MW

240

Command + State

→ 0

→ STOPPING (5)

Shutdown command; min_up_time satisfied (~172 min on), begins stopping sequence

~250

State

0

→ OFF (0)

Power reaches 0 (ramped down at 10 MW/min), turbine off

360

End

0

OFF (0)

Simulation ends

Key Behaviors Demonstrated#

  • Minimum down time: The turbine cannot start until min_down_time (60 min) is satisfied, even though the command is issued at 40 min

  • Hot startup sequence: After min_down_time, the turbine enters HOT STARTING, waits through hot_readying_time, then ramps to P_min using run_up_rate

  • Ramp rate constraints: All power changes in ON state are limited by ramp_rate (10 MW/min)

  • Minimum stable load: When commanded to 10 MW (below P_min = 20 MW), power is clamped to P_min

  • Minimum up time: Shutdown is allowed immediately at 240 min because min_up_time (60 min) was satisfied long ago

  • Stopping sequence: The turbine ramps down to zero at ramp_rate before transitioning to OFF

Setup#

No manual setup is required. The example uses only the OCGT component which requires no external data files.

Running#

To run the example, execute the following command in the terminal:

python hercules_runscript.py

Outputs#

To plot the outputs, run:

python plot_outputs.py

The plot shows:

  • Power output over time (demonstrating ramp constraints and minimum stable load)

  • Operating state transitions

  • Fuel consumption tracking

  • Heat rate variation with load

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