Recursive data reconciliation with nonlinear characteristic constraints for typical heat exchangers in nuclear power plant

Data reconciliation has been extensively studied in the Nuclear Power Industry because of its benefits including reducing the uncertainty of measurement data and economic superiority. Previous reconciliation methods usually neglect necessary characteristic constraints, causing certain deviation under stable or dynamic situations. By making full use of redundant information from equipment thermodynamic state equations and control transformation functions, a recursive data reconciliation method is proposed to narrow estimation deviation in two aspects. First, different reconciled methods including implicit method, explicit method, coupled method and synthesized method were established based on bilinear orthogonal transformation. Second, recursive process was designed for reconciliation between virtual device and real device. Two typical heat exchanger systems in nuclear plant were selected as case studies. Results show that the proposed reconciliation method decreases the system error in both stable and dynamic situations. Moreover, when implementing the new proposed data reconciliation method to a preheating system with two heat exchangers, it can converge to the specified residual error within 10 iterations. Recursive reconciliation method which was proposed in this paper provides systematic guidance for nuclear power plant operating and maintenance involving data reconciliation.