Study On Design Methods Of Hydropower Plant Ventilation Systems In The Underground Excavation Cluster Based On Network Analysis

The hydropower plant has occupied the very important position in improving Chinese energy sources building, and with the increase of the size of the hydropower plant, its ventilation and air conditioning systems will be more complex. At present, the traditional design method of the ventilation and air conditioning systems in the hydropower plant, especially in the underground hydropower plant, which is mainly by experience and scientific calculation secondarily, is based on comparative study, and the calculation is usually done manually. The disadvantage of this method lies in ignoring the interaction among related systems, which leads to the great difference between the theoretic calculations and the actual running conditions. As a result, the deployment of the design method of the hydropower plant ventilation and air conditioning systems in the underground excavation cluster has great practical meanings.This paper integrates the related hydropower plant ventilation systems in the underground excavation cluster, analyzes and calculates the hydropower plant ventilation systems in the underground excavation cluster by the network analysis methods based on numerical method, graph theory and optimization theory, so as to improve and optimize the existed design and type-select methods.During the course of ventilation, the underground excavation cluster is a ventilation system consisted of traffic cavity, workshop, busbar galleries, main transform chambers, out going line gallery, air supply gallery, air exhaust gallery and so on, as well as the specially setting air supply duct and air exhaust duct. The paper converses the ventilation system into branches and nodes and then expresses the connecting relation between the branches and nodes by dimensional line, using the related system of graph theory. Besides, the factors affecting the air flowing of the branches are expressed by impedance of the branches, and then the calculate principle and method of the branch impedance is presented, In this way, the ventilation network sketch of hydropower plant in the underground excavation cluster comes into being. In the following, the paper lists node flux balance equation group and loop pressure balance equation group, based on law of conservation of mass and law of conservation of energy, and the relation between flux and pressure elicits, using the law of branch ventilation resistance and the relation of fan performance. Then this equation is put in node flux balance equation group or loop pressure balance equation group to seek asolution, then the flux and pressure of the branches elicit. Comparing the various methods, the paper presents the calculation methods of hydropower plant ventilation systems in the underground excavation cluster.The paper considers the stability of the ventilation system through branches and network. In the beginning, the differentiating and adjusting method of diagonal branches and its airflow direction is presented, and estimates the key affect branch by the method of orthogonal experiment. In the following, the impacting area is defined, and the affects on ventilation system of various factors are analyzed, the statistical analyzing index related to the stability of ventilation system is presented.According to the design method, the paper takes the example of the LT hydropower plant. Analysis and calculation are carried through, and the corresponding suggestions for adjustment are presented, which provides methods and viewpoints for the ventilation systems of hydropower plant in the underground excavation cluster.