Hi, I am working on an OpenStudio measure of an electrical storage device. During its charging phase, the device is meant to be charged according to the difference between a user-defined maximum building power and the current power demand of the building (building_power_dmd). This value is referred to as 'available_charging_power'.
Hence, the electrical charging power for the storage device, referred to as 'storage_electric_pwr', should be limited by the 'available_charging_power' variable.
My problem is twofold: First, a problem arises from the global variable 'Facility Total Electricity Demand Rate' containing within itself the 'storage_electric_pwr' value of the last timestep. Technically, this shouldn't be a problem since I am using global variables and can retrieve previous values. However, I cannot be sure of the exact values contained in the 'Facility Total Electricity Demand Rate' variable (previous or current demand values) since the storage device is a user-defined plant component and I am unsure whether the Erl program is launched before or after other plant calculations. How can I know what value is contained within the global variable 'Facility Total Electricity Demand Rate' at the beginning of the Erl execution? Is this value updated in real-time during the execution of the Erl program?
Secondly, I am also unsure if, how, and when the Erl program reiterates itself within the same timestep. I haven't found a built-in reiterate function in the EMS documentation but that might also be the main reason I cannot get a working program. Since the 'storage_electric_pwr' and 'available_charging_power' variables depend on each-other, this loop seems to spiral out of control. I coded the Erl with the intent of keeping the previous timestep value for storage_electric_pwr and substracting it from the Facility Total Electricity Demand. What would you recommend in order to keep the value from changing within the same timestep? Would a Trend variable be adequate? If so, is there a function to call a single value from a Trend Variable instead of the min, max and avg trend functions?
Here is the link to the source code: https://github.com/Houssem-Eddine-Younes/Openstudio_measures
Disclaimers: I am not the original programmer and the contacts on the GitHub page aren't mine. Some changes have also been made to the original code.
Thanks for your help.
