A new approach to statistic processing of steam parameter measurements in the steam turbine path to diagnose its condition

摘要

Technical diagnostics for the steam paths of large steam turbines can be conducted on the basis of regular steam parameter measurements in the turbine. Solution of this problem is to a great degree tied to raising the confidence of appraising the deviations of the currently measured parameters from their normative values for the undamaged steam path. A proper statistic processing of the measured data allows tracing the turbine's steam path condition on-line with more confidence. Thus, for example, for the high-pressure sections, the steam temperature after the section is one of the most representative diagnostic indicators (symptoms). A newly developed appraoch makes it possible to decrease the standard deviation for this value to 0.8 deg C and recognize reliably the changes of the measured steam temperature values as compared with its normative value even not exceeding 2-3 deg C. The same is true for the deviations of other measured variables employed as the diagnostic parameters. The developed appraoch isverified as applied to the actual reaction-type steam turbine in its long-term operation under both stationary and transient operating conditions with the use of the data taken from the unit's computerized Data Acquisition System.