The least squares support vector machine(LS-SVM)and RBF kernel function model were applied to calculate the target value of terminal temperature difference of low-pressure heaters

and performance evaluation of the heaters was conducted according to the difference between the target value and measured value.Taking normal operation state of the No.6low-pressure heater in a 300MW unit turbine as the example

the feasibility of using the LS-SVM model to calculate the target value of terminal temperature difference of the low-pressure heater was verified.Finally

economical efficiency of the heater at fault state was evaluated by the LS-SVM model.The results showed that

the mean square deviations between the measured and target value of upper and bottom terminal temperature difference of the heater were 0.536 3℃and 5.055 3℃

respectively

both far larger than that at the normal operation state(0.005 3 ℃ and 0.007 8 ℃).This indicated fault has happened on the heater.The inspection validated that

leakage occurred on bypass door between the No.6and No.7low-pressure heater

and water level in the No.6lowpressure heater was too low.Therefore

the LS-SVM model was preferred to evaluate the economic efficiency of the low-pressure heater's performance

and it also can discover the heater fault at an early time.