A Ladder Ascending Control Chart with Application in Wind Energy Industry

Statistical process control is extensively applied for monitoring the production process. One of the important tools of statistical process control for detecting the unusual changes in the manufacturing process is the control chart. In the use of a control chart, samples or subgroups are selected in a manner that if unusual changes are present, the chance for differences between subgroups will be maximized, while the chance for differences within a subgroup will be minimized. However, there are different practical engineering processes where this assumption would not be applicable. In this paper, we considered a Wind Energy process where differences within a subgroup are significant and proposed a new control chart namely Ladder Ascending Control Chart under this situation. The Ladder Ascending Control Chart is based on order statistics by using order statistic distribution as the underlying distribution. Shewhart type control limits formulae for the order statistic mean have been built. It is applied to wind energy for monitoring the wind speed using the Weibull distribution as the underlying distribution of wind speed. The average run length is provided as a performance measure for the Ladder Ascending Control Chart. A real-life example is provided for its application and interpretation.