New Elastic Model of Pipe Flow for Stability Analysis of the Governor-Turbine-Hydraulic System

A higher-order elastic model of the flow in long pressurized pipelines is expected to be utilized for stability analysis of the governor-turbine-hydraulic system in hydropower stations. Because traditional elastic models are limited in lower order application because of their difficult decoupling in addition to the rigid model, a new linear elastic model of the flow in pressurized pipelines is derived on the basis of the equations of hydraulic vibration, in which each oscillatory flow with a different order has been obtained with ordinary differential equations in decoupling form. For water conveyance systems with branching pipes or parallel pipes in hydropower stations, the state equations to describe hydraulic characteristics of the governor-turbine-hydraulic system are established with the application of this new elastic model for diversion pipeline flow or tail tunnel flow. The influence of the elastic models with different order on a system's stability are revealed in detail by two cases that illustrate that an elastic model with proper order should be used for the flow in pressurized pipelines of hydropower stations, according to their length, to improve the accuracy of stability analysis. DOI: 10.1061/(ASCE)HY.1943-7900.0000433. (C) 2011 American Society of Civil Engineers.