Reduce The Large Hydropower Station Tailrace Surge Shaft Area

Hydropwer station with leading water usually has a long leading tunnel.When there is a high modification of load on turbines, a very high rushing pressure will be built in the tunnel. To avoid the situation, a pressure adjusting well is required to be built.A pressure adjusting well located in the upper reach is called upper reach pressure adjusting well while is called lower reach pressure adjusting wellIn a large hydropwer station, the downstream surge tank is usually so much huge that it is usually very difficult to build, cost so much time to build and costs a lot of money.In this paper, the numerical method on the analysis of internal characteristic is applied to solve the oscillation in a surge tank during the transient process of a water turbine. And the stability of such a kind of hydropower station is analised by Nyauist's method with the characteristics of pressure pipe, tunnel, surge tank, governor, water turbine, generator and electricity supply system having been fully considered, Calculations and experiment show that the area of a downstream surge tank can be reduced on a large scale by using the mathmatical model and method in the paper.The calculation shows that the numerical results are very close to the practical measuring results and therefore the method is correct and the mathematical model is correct.By using the method to calculate the surge tank in Dachaoshan hydropwer station, the area of the surge tank can be greatly reduced.