Abstract
The control valve is an important piece of equipment in the steam turbine, which frequently suffers from the fault of the dead zone. The graph model is a promising method for dead zone detection, yet establishing an accurate and completed graph topology is not an easy task due to limited mechanism knowledge. Hence, a graph model is proposed to predict the links in the graph and estimate the relationship between variables of related equipment of the control valve. The graph convolution is conducted on the uncompleted graph to learn the low-level representations of the graph nodes, and the score function is used to evaluate the probability of the existence of links between a pair of graph nodes. Results demonstrate a test accuracy of 99.2% for the link prediction, and follow the principles of thermodynamics in the steam turbine. Consequently, the proposed graph model is capable of estimating the relationships for the steam turbine control valve, and other inter-connected industrial systems.
Highlights
Introduction mechanical coupling is availableFor SKC32.. and SKC82.. actuators the Y1signalThe musthigh be routed via an additional (ASC9.3)to limit pressure controlfreely-adjustable valve is oneend of switch the most important pieces of equipment the stroke.in the steam turbine, which governs the steam flow and regulates the power generation.We recommend that you contact your local Siemens office for the necessaryFigure illustrates the working mechanism of the control valve
The results of graph topology prediction Ĝ can reveal the relationships between physical variables related to the control valve, which are represented by the links between graph nodes
For the simulation of the fault, a dead zone block is connected between the PID controller output and the opening of the high pressure control valve, and a 15% dead zone is injected into the valve, with the simulation time of 2400 s
Summary
Fault detection and diagnosis based on the graph model is a promising technology owing to its strong reasoning ability. Since opening of the valve is controlled by pressure pm , and eventually regulates the steam flow into the high pressure cylinder, the fault node dead zone is connected to pm and Qhp. Obviously, according to the steam turbine mechanism, the mass flow rate of the main steam Qm is directly related to the mass flow rate of the high pressure cylinder Qhp , so do Qex and Qex. The results of graph topology prediction Ĝ can reveal the relationships between physical variables related to the control valve, which are represented by the links between graph nodes
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