Pressure Control Studies for PG&E's 20 MW Grizzly Hydroelectric Project

by Thomas Logan,
Richard D. Stutsman,

Document Type: Proceeding Paper

Part of: Waterpower '91: A New View of Hydro Resources


The Pacific Gas and Electric Company's Grizzly Hydroelectric Project consists of a single 20 MW Francis turbine under 700 feet head located near the existing Bucks Creek Project. A proposed 12 foot diameter tunnel, 12,100 feet long carries flows from the forebay to a surge tank, from which it joins a 5000 feet long, 90 inches diameter penstock that delivers flows to the turbine. The project is in an environmentally sensitive area and care has been provided in both the alinements and construction to preserve existing values. Details of the Howell Bunger pressure regulating valve operation to control waterhammer are given. Design criteria for critical operations under failure conditions are described. The effect of the lengthy penstock on waterhammer and speed rise considerations are also discussed. The sizing of bursting plates is reviewed for the Grizzly project in which the lengthy penstock has an adverse profile. The Grizzly Project acts as a peaking plant in the PG&E System, as a result stable governing is required, however frequency regulation is not a requirement.

Subject Headings: Hydro power | Water hammer | Electric power | Water pressure | Power plants | Head (fluid mechanics) | Rivers and streams | Water storage

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