Returns the voltage angle and generator set-point vectors.

def _update_solution_data(self, s):
        """ Returns the voltage angle and generator set-point vectors.
        """
        x = s["x"]
#        Va_var = self.om.get_var("Va")
#        Vm_var = self.om.get_var("Vm")
#        Pg_var = self.om.get_var("Pg")
#        Qg_var = self.om.get_var("Qg")

        Va = x[self._Va.i1:self._Va.iN + 1]
        Vm = x[self._Vm.i1:self._Vm.iN + 1]
        Pg = x[self._Pg.i1:self._Pg.iN + 1]
        Qg = x[self._Qg.i1:self._Qg.iN + 1]

#        f = 0.5 * dot(x.T * HH, x) + dot(CC.T, x)

#        s["f"] = s["f"] + C0

        # Put the objective function value in the solution.
#        solution["f"] = f

        return Va, Vm, Pg, Qg