Add combined-cycle gas turbine class with default values

[genevievestarke]

Add a class for a combined-cycle gas turbine with default operation values.

To-do:

• Create class
• Create example
• Create tests
• Update documentation
• Remove Example 08 docs and update Example 07 to include CCGT

[genevievestarke]

Quick question I ran into when implementing an example @paulf81 @misi9170 : Do we want to count start-up time and shut-down time in the time_in_state variable? It currently is included.

In the open cycle gas turbine, it doesn't matter a whole lot, but in the combined cycle, the times are much longer (180 minutes for a cold start), and a minimum up time of 4 hours, which means that the cold start is 3/4 of the minimum up time just to start up. I think the minimum up time should be computed from when the unit starts producing power rather than when it starts it's warm up. Thoughts?

[paulf81]

Quick question I ran into when implementing an example @paulf81 @misi9170 : Do we want to count start-up time and shut-down time in the time_in_state variable? It currently is included.

In the open cycle gas turbine, it doesn't matter a whole lot, but in the combined cycle, the times are much longer (180 minutes for a cold start), and a minimum up time of 4 hours, which means that the cold start is 3/4 of the minimum up time just to start up. I think the minimum up time should be computed from when the unit starts producing power rather than when it starts it's warm up. Thoughts?

Hi @genevievestarke , I think that's how it works now. For example in the cold start state:

        # ====================================================================
        # STATE: COLD_STARTING
        # ====================================================================
        elif self.state == self.STATES.COLD_STARTING:
            # Check if startup should be aborted
            if power_setpoint <= 0:
                self.state = self.STATES.OFF
                self.time_in_state = 0.0
                self.power_output = 0.0
                return 0.0

            # Check if readying time is complete
            if self.time_in_state < self.cold_readying_time:
                return 0.0

            # Ramp up using run_up_rate
            startup_power = (self.time_in_state - self.cold_readying_time) * self.run_up_rate

            # Check if ramping is complete
            if startup_power >= self.P_min:
                self.state = self.STATES.ON
                self.time_in_state = 0.0
                return startup_power

            # Limit to below P_max (edge case)
            startup_power = np.clip(startup_power, 0, self.P_max)

            return startup_power

You can see that when ramping is complete and it transitions to STATES.ON, self.time_in_state is then reset to 0.

[genevievestarke]

Hi @genevievestarke , I think that's how it works now. For example in the cold start state:

Ah, yep, you're right @paulf81 ! I went back a verified that in the example and it all looks to be working.

[misi9170]

Perhaps an idea is to add the CCGT response to example 07 so that the OCGT and CCGT responses can be compared side by side, rather than have a separate example?