An on-line energy consumption calculation method for thermal power units has been put forward on the basis of symphony system from ABB Corporation in USA.Taking BRC 300 as the operational controller

the runing parameters of units are obtained on-line from the DCS

to compile the C language programm

and being embedded in Symphony DCS;by using the equivalent enthalpy reduction method and anti-balance method

the running situation of units has been analysed

and the energy consumption characteristics of units being calculated and obtained.The results of calculation are compared with the practical results of thermal tests

the relative error of specific heat consuption is 0.5%

and the relative error of boiler efficiency is 0.42%

it shows the feasibility of this on-line calculation method.