def set_active_design(oProject, designname):
    """
    Set the active design.
    
    Parameters
    ----------
    oProject : pywin32 COMObject
        The HFSS design upon which to operate.
    designname : str
        Name of the design to set as active.
    
    Returns
    -------
    oDesign : pywin32 COMObject
        The HFSS Design object.
        
    """
    oEditor = oProject.SetActiveDesign(designname)
    
    return oEditor