# Question about REECCU1

The text below is from the Model User Guide for Renewable Energy System Models:

Consider a simple example of how the reec_c model might be parameterized to represent a BESS. Assume we have a BESS that is rated at 40 MVA, with an energy rating of 30 MWh for 4 hours. Also, let us assume that when in operation the BESS is required by the vendor to always be in a state of charge between 20% to 80%, with the same charging rate (i.e. 4 hours). Then, SOCmax = 0.8 SOCmin = 0.2 The total energy of the device = 30×4 = 120 MWh, thus in operation it can go from 0.8×120 (96 MWh) to 0.2×120 (24 MWh), which means that the maximum output would be (96 – 24)/4 = 18 MWh for 4 hours. Therefore, T = ((18/30) × (60×60×4)) / (0.8 – 0.2) = 14,400 Pmax = 18/30 = 0.6 Pmin = - Pmax = -0.6 Imax = 40/30 = 1.33 The model MVA = 30 MVA. All other parameters would be set per the OEM data.

Questions: 1. Is the model MVA = 30 MVA to be placed in the MBase of the generator in the power flow? 2. Do I need to place the Pmax/Pmin also in REPCAU1 or only in REECCU1? 3. The text "energy rating of 30 MWh for 4 hours" is a little bit confusing since it mentions that the total energy is 30x4 = 120 MWh. The value 120 MWh would be possible only if 30 is in terms of MW not in MWh. Am I missing something here?