Data Reconciliation and Suspect Measurement Identification for Gas Turbine Cogeneration Systems

Abstract

Data reconciliation is widely used in the chemical process industry to suppress the influence of random errors in process data and help detect gross errors. Data reconciliation is currently seeing increased use in the power industry. Here, we use data from a recently constructed cogeneration system to show the data reconciliation process and the difficulties associated with gross error detection and suspect measurement identification. Problems in gross error detection and suspect measurement identification are often traced to weak variable redundancy, which can be characterized by variable adjustability and threshold value. Proper suspect measurement identification is accomplished using a variable measurement test coupled with the variable adjustability. Cogeneration and power systems provide a unique opportunity to include performance equations in the problem formulation. Gross error detection and suspect measurement identification can be significantly enhanced by increasing variable redundancy through the use of performance equations. Cogeneration system models are nonlinear, but a detailed analysis of gross error detection and suspect measurement identification is based on model linearization. A Monte Carlo study was used to verify results from the linearized models.

Enhanced turbine monitoring using emissions measurements and data reconciliation

“…We equate the energy balances for the compressor and gas generating turbine giving six energy balances and two material balances. We performed the data reconciliation using the measured variables provided in Table 1; additional details for performing data reconciliation are provided elsewhere [28,29]. Reconciled values for measured variables including , , and , were determined.…”

“…This exemplifies the difficulties associated with gross error detection through data reconciliation. An error is often smeared into the errors of other measured variables during data reconciliation (see [29] for further discussion). Variable threshold calculations [20] provide further insight into these difficulties.…”