I am using a PlantComponent:UserDefined (PCUD) object to model a sensible heat storage, used as central heating plant equipment. The device's maximum capacity in kW is dependent on its state of charge (SOC) which is a function of its charge temperature at each time step. As an example, at a maximum charging temperature of 800 °C the device can deliver a maximum of 75kW; at 100 °C a maximum of 10kW can be extracted, etc.
The PCUD object has an actuator called Maximum Loading Capacity. During initialization, when I set the actuator value to 75kW, this seems to permanently register the device's maximum capacity to 75kW. I believe the value of this actuator is captured once during the sizing phase by EnergyPlus. However, as mentionned, the maximum capacity of the device varies according to its storage temperature. As a consequence, during the run period simulation, the device is being loaded to its absolute maximum of 75kW even though its maximum capacity at a given timestep is below the absolute maximum of 75kW. This problem can also be seen when the load is being distributed between the storage device and another equipment, such as a boiler.
For example, say the storage device is operating alongside a NG boiler. The storage device has priority, and has a maximum capacity of 50kW at a given timestep. The total load on the demand side is 150kW. What happens is the storage device gets loaded to 75kW (instead of 50kW) and the remainder (75kW) is taken by the boiler. The device only delivers 50kW out of the 75kW that it's being asked to meet, resulting in 25kW of unmet load that could have been distributed and delivered by the boiler.
Is there a way to update the maximum loading capacity of the PCUD object at each timestep? In other words, override the absolute maximum value of 75kW that is read during initialization?
