model VVsourceAC "Sin-wave voltage source" Pin p, n; Real v; Real VA "voltage"; parameter Real f = 50 "Frequency"; parameter Real PI=3.141592653589793; equation v = VA*Modelica.Math.sin(2*PI*f*time); v = p.v - n.v; 0 = p.i + n.i; end VVsourceAC;