The three-bus power system shown in the figure has one alternator connected to bus 2 which supplies 200 MW and 40 MVAr power. Bus 3 is an infinite bus having a voltage of magnitude |V₃|=1.0 p.u. and an angle of -15°. A variable current source, |I|∠φ, is connected at bus 1 and controlled such that the magnitude of the bus 1 voltage is maintained at 1.05 p.u. and the phase angle of the source current, φ=θ₁±π/2, where θ₁ is the phase angle of the bus 1 voltage. The three buses can be categorized for load flow analysis as _______.