The calculated flow of the original DCS main steam flow model has large deviation.Thus the temperature after the governing stage was replaced by the extraction steam temperature of the first stage to conduct correction calculation.Moreover

the first stage extraction steam temperature(387℃)in the rated load operation cycle efficiency test was regarded as the reference temperature.The results show that

the largest relative deviation of main steam flow value calculated by the original model and the improved model was less than 0.8%.Parameters of the modified main steam flow model changed smoothly with the unit load.