An exemplary control system performs a control and fault analysis method in a thermal power plant using plant data specifications during normal operation of the plant. The method includes obtaining information for at least one set point from the plant data specification which includes a list of process parameters and process outputs. One or more control loops are controlled by providing set points for control based on the information obtained for the at least one set point to operate the thermal power plant and identifying gaps in controlling the one or more control loops in the thermal power plant specification and at least one set point is iteratively manipulated to meet the demand. Further, the plant data specification is updated based on the manipulated at least one set point used to meet the demand, and the updated plant data specification is used for controlling the plant to meet the demand.