Data reconciliation for steam turbine on-line performance monitoring

In a coal-fired power generation unit, steam turbine performance monitoring relies on steam cycle heat balance analysis, in which the primary flow measurement accuracy is critical. However, in a steam turbine on-line measurement system, the accuracy of most flow metering devices is not satisfactory, and using data measured with these devices could lead to high uncertainty in the heat balance analysis and performance monitoring results. In this work, we propose a data reconciliation approach in steam turbine on-line performance monitoring, with the aim of reducing uncertainty of the primary flow measurements and steam turbine heat rate. The proposed method is based on the establishment of a first-principle mathematical model of a steam turbine unit and optimization of the reconciled values of measurements. Results of a case study carried out on a real-life 1000 MW ultra-supercritical unit show that, after data reconciliation, uncertainties of measured values of the outlet flow rate of the #1 feed water heater, the outlet flow rate of the feed water pump, and the inlet flow rate of condensate water in the deaerator can be reduced by 72.1%, 39.4% and 21.4%, and that uncertainty of the steam turbine heat rate can be reduced by 17.9%, 18.8% and 18.8%, when the unit operates at 100%, 75% and 50% of its design load.