How to integrate action variables of logic type into the split range control structure?

Question

I have following control task. I have to limit a current drawn from a source of power in a grid where I have following power consumptions:

1. battery charger
2. variable frequency drive
3. aux power consumption 1
4. aux power consumption 2

The current drawn from the source of power can be limited via these action variables:

1. lowering the charging current setpoit for the battery charger
2. lowering the torque setpoint for the variable frequency drive
3. activating the logic input of the aux power consumption 1 for turning the consumption off
4. activating the logic input of the aux power consumption 2 for turning the consumption off

(the action variables above are ordered according to their priorities, where the first one has the highest priority i.e. this action variable is the action variable of the first choice and the others are activated only in case the influence of their predecesor isn't sufficient)

I have been thinking about the control structure suitable for this control task. It seems to me that the so called split range control could be a solution (at least as far as the first two action variables). The problem which I have regards the last two action variables. I am not sure how to integrate them organically into the split range control structure. The idea which I have is depicted on below given figure

i.e. the logic signals are simply activated based on the value of the output of the PI controller in the same manner as the charging current setpoint and torque setpoint. I am not sure whether this approach can work in practice. Does anybody know a better approach for integration of action variables of logic type into split range control structure?

Answer 1

I think that the possible solution could be to let the split range controller produce only:

1. charging current setpoint
2. torque setpoint

The logic signals for turning the auxiliary consumptions off will be produced by two hysteresis controllers. Those controllers will be enabled only in case the split range controller has both of its outputs at their lower limits.