Consider the two power systems shown in Fig (a) below, which are initi ally not interconnected, and are operating in steady state at t he same frequency. Separate loadflow solutions are computed individually for the two systems, corresponding to this scenario. The bus voltage phasors so obtained are indicated on Fig (a). These two isolated systems are now interconnected by a short transmission line as shown in Fig (b), and it is found that P₁ = P₂ = Q₁ = Q₂ = 0

The bus voltage phase angular difference between generator bus X and generator bus Y after the interconnection is