Safe control of air cushion surge chambers in hydropower systems

This paper presents an effective theory for safe control of Air Cushion Surge Chambers (ACSCs) in hydropower systems. On the basis of the emergency pressures and heights of air in chambers, the acceptable limits of the monitoring parameters for three kinds of control mode are derived theoretically to control the air compressor. The prerequisites for each control mode are determined by considering air leakage and the solution. By analyzing these prerequisites, the selection criteria are established to determine the appropriate control mode for a practical hydropower system with ACSC. According to the presented control scheme, the air compressor need not be actuated for any variation in air temperature, and the operating conditions of the hydropower system need not be considered for safe control of ACSCs. Those are favorable for the safety and economy of the hydropower plant. To detail and validate the derived limits and selection criteria for different control modes, the safe control theory is applied to the practical hydropower plant, and a graphic analysis is conducted on the basis of the perfect gas law and the relationship of the initial steady-state pressure and height of the enclosed air in the chambers. (C) 2013 Sharif University of Technology. All rights reserved.