A joint programming method adopting Symphony DCS Composer configuration language and C language made from ABB Corp in USA has been put forward

adopting C language to draw up the on-line performance calculation programme

the Composer configuration language is used for calling the C language programme

taking the real-time data of DCS as the calculation data

the performance of energy cosumption can be calculated and obtained.The C language programme contains the calculation programmes of enthalpy and entropy values based on IAPWS-IF97 formula

creating an integrated calculation environment

it is unnecessary to call other programmes

resolving the limitations for complex algorithms existing in DCS configuration language

realizing the on-line performance calculation of units.Taking 60 MW unit no.2 in one power plant as the object of study

the coal consumption under unit load of 660 MW has been calculated

the error of calculated results is within an allowable range

showing the on-line calculation method is feasible.