Q:   Do I have to include load in my short circuit network and solve the powerflow for accurate IBR simulation and if so how?

A:   Loads will cause current in the network in both prefault and fault states. These currents influence the magnitude and angle of voltages in the network, determining the initial conditions used to calculate the IBR fault currents.  Therefore, load modeling may be necessary in some portions of the system to achieve a more accurate solution.  For example, it may be necessary to model load in portions of the system where the fault current magnitude is close to the load current magnitude (weak grid).  Another example might be locations within the network that are subject to significant power transfer.  Keep in mind that adding load to the cases will require additional modeling adjustment steps to balance load and generation in the prefault condition.