ProjectLocation location = m_application.ActiveUIDocument.Document.ActiveProjectLocation;
Autodesk.Revit.DB.XYZ origin = new Autodesk.Revit.DB.XYZ (0, 0, 0);
ProjectPosition projectPosition = location.get_ProjectPosition(origin);
//change the offset value of the project position
projectPosition.Angle = newAngle * Modulus; //convert the unit
projectPosition.EastWest = newEast;
projectPosition.NorthSouth = newNorth;
projectPosition.Elevation = newElevation;
//set the value of the project position
location.set_ProjectPosition(origin, projectPosition);
m_application.ActiveUIDocument.Document.ActiveProjectLocation = location;