Abstract
In the energy generation business steam powered turbo-generators still play an important role in electrical power generation all over the world. Every facility using steam turbines considers them as the critical machinery. Such machines should be well-maintained, properly handled, and precisely diagnosed in order to achieve the best performance and safety. The most valued data about the technical health are collected during machine’s shut-downs and run-ups. These data are more than seldom and hard to assess without expert’s knowledge with strong theoretical background and experience. Main novelty of the paper is the automated method for novelty detection of machine’s vibration. Most proposed methods apply to smaller machines with rolling bearings, whereas we propose the method for large machines with sliding bearings, which have much different behavior. The application of the method is support of the plant maintenance staff to evaluate deviations of turbo-sets from a healthy state based on the concept which we called the Operating Envelope. The envelope is created based on the data from a vibration sensor during the transient state. In this paper we consider a single vibration sensor and only the first harmonic amplitude of this signal. To set the acceptance limits within which turbo-set’s dynamic response will be considered as acceptable, we used the cubic spline interpolation coupled with expert judgement. Beyond these limits the state of the turbo-set is considered as unhealthy, so it is an automated fault detection method. In such a case a machine should be a subject to further and deeper diagnostic analysis. The method was validated on the data from the 13K242 type (a 200 MW class turbine) steam turbine. We also proposed a set of parameters to evaluate the severity of malfunction.
Highlights
In the energy generation business steam powered turbo-generators still play an important role in electrical power generation all over the world
The survey by Xiao et al [1] presents the main components of a fossil-fuel power plant (FFPP) and its importance as well as its share in the world power generation industry
As new diagnostic technologies are being developed, e.g. state-of-the-art thermal and flow diagnostic of steam turbines and introduced to power plants, still vibration response of the unit remains the fundamental method to assess the technical state of turbo-sets
Summary
In the energy generation business steam powered turbo-generators still play an important role in electrical power generation all over the world. The best industrial practice is to assess machine dynamic state during each and every transient state operation, i.e. a shutdown and a start-up. The authors proposed such a method and coined a name Operational Envelope (OpEn) This idea is based on an envelope wrapped around 1st harmonic amplitude during the transient state of the machine. The method we propose can be applied to large power generation machines, which have very different dynamic behavior. They are equipped with sliding bearings, which have highly non-linear characteristics and may exhibit unique malfunctions, e.g. oil film instabilities. Large machines operate over the first (sometimes even second) critical speeds and novelty detection method must be able to tackle the resonance data
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