The Effect of Surge Tank Throttling on Governor Stability, Power Control, and Hydraulic Transients in Hydropower Plants

Abstract

This paper investigates the effect of surge tank throttling on governor stability, power control, and hydraulic transients in hydropower plants. The work is intended to be practical, but includes some new research. The practical contributions include a methodology for a combined evaluation of the effects of installing surge tank throttles in hydropower plants, and a demonstration of the throttle effects through a case study. The research contributions include the evaluation of the throttle effect on power control, and a comparison of the throttle effects on power control for governor systems with speed feedback exclusively versus combined speed and power feedback. Field measurements are used to calibrate a numerical model of the case-study hydropower plant. The results from the case study show that the throttle has an insignificant positive impact on governor stability. Power control is improved when a throttle is installed; the overshoot of produced power and the time until steady-state conditions occur are reduced. The throttle has a significant effect on the hydraulic transients, and increases the water hammer and reduces the mass oscillations in the system.

Investigation of Water Hammer Protection in Water Supply Pipeline Systems Using an Intelligent Self-Controlled Surge Tank

“…Apparently, a constant connector cannot always work at the best condition. This is in good agreement with Vereide et al's [4] previous work, in which the effect of the throttling shows a similar law.…”

“…Except for improved operations in long water supply systems [1], devices such as surge tanks [2][3][4], air chambers, and air valves [5,6] are widely used in some projects to ensure the running security. By breaking the continuity of the pressure conduits, the water-carried energy can be rapidly released by vibrating it up and down in surge tanks [4]. In recent decades, numerical simulation has become the main approach for transient analysis with the development of computer science [7].…”

“…Although a common surge tank is enough to satisfy most applications, there is still much room for improvement. Vereide and Svingen [4] investigated the effects of a surge tank throttling on hydraulic transients in a hydropower plant system. The result shows that the throttling can bring some slight improvement in transient pressure control.…”

Design of a Nonlinear Predictive Controller for a Fractional-Order Hydraulic Turbine Governing System with Mechanical Time Delay

“…It is particularly important for such giant hydro-turbine units to ensure their safe and stable operation [4][5][6]. However, there are varying degrees of stability problems in large and medium-sized hydroelectric generator units in production practice both at home and abroad [7][8][9][10]. The stability of the hydro-generator sets plays an important role in the stability of the power grid system.…”

Design criteria for a type of asymmetric orifice in a surge tank using CFD

“…Stability criteria define the minimum area of the shaft (Thoma, 1910;Ye et al, 1992) and the storage capacity can be enhanced with additional chambers. Large mass oscillations between the surge tank and the upper reservoir can be further damped with the addition of a throttle (Adam et al, 2018a;Li & Brekke, 1989;Vereide et al, 2017). Such a structure can be added in the connection between the surge tank and head race tunnel or at a change of the cross section (Adam et al, 2016a;Richter et al, 2015).…”