How would you determine the Thevenin equivalent source parameters V s and Z s of the entire

Question:

How would you determine the Thevenin equivalent source parameters V_s and Z_s of the entire power grid bringing power to the wall outlet at your workplace? Answer separately assuming that (1) the source reactance is negligible, that is, Z_s = R_s (a pure resistance), and (2) the source reactance is not negligible, that is, Z_s = R_s + j X_s.