Torque model of hydro turbine with inner energy loss characteristics

Abstract

This paper presents the result and analysis of the composition of energy loss occurring in the hydro turbine. Two new types of energy losses, namely the hydraulic loss in the flow channel and the impact loss, are defined. All losses within the hydro turbine are divided into four types and the loss coefficients are defined accordingly. Expressions or characteristic descriptions of these losses as well as the calibration method of the loss coefficients are presented. Furthermore, the torque model of the hydro turbine where the inner energy loss takes place is established. The developed model has been used to calculate the power loss due to the mechanical friction generated by the units' rotation to solve the difficulty of measurements of the mechanical friction loss in the hydro turbine. The definition of the impact loss explains the phenomenon that the loss of no-load is greater than that of the rated operation. A set of conversion coefficients are defined using the characteristic parameters at the rated operation, which are used to transform the parameters in the torque model into those that are easily measured. Therefore, the expression of the hydro turbine power is converted into a function that has the main servomotor displacement as its single variable. This makes the proposed model be convenient to use. Finally, the proposed model and methods are calibrated and verified using the measured data of a hydropower plant. Good agreement between the modeled results and the measurements indicates that the proposed model can represent the inner energy loss characteristics of the hydro turbine.hydraulic loss in flow channel, impact loss, loss coefficients, conversion coefficients Citation:Zeng Y, Guo Y K, Zhang L X, et al. Torque model of hydro turbine with inner energy loss characteristics.

Reconstruction of the complete characteristics of the hydro turbine based on inner energy loss

“…(1) and the calculation method of the characteristic parameters in the next section have been verified using an actual field measurement data for efficiency test of hydro turbine [20]. For details of the field measurements, readers are referred to [20]. Remark 1: At the optimum operation of the hydro turbine, there is no water flow impacting on the inlet of the turbine runner while water outflow moves along the normal direction at the outlet of the turbine runner.…”

“…(1) and the calculation method of the characteristic parameters in the next section have been verified using an actual field measurement data for efficiency test of hydro turbine [20]. For details of the field measurements, readers are referred to [20].…”

“…Refer to the turbine model with the inner energy loss characteristics in [20], the inner energy of the hydro turbine composition can be written as following:…”

“…For convenient comparison, the hydraulic loss item is ignored when calculating the turbine power by Eq. (20); meanwhile H 0 is adjusted to maintain a constant head so that the computation is consistent.…”

“…The method employed the structure parameters of the hydro turbine to calculate the turbine torque. The inner energy composition within the hydro turbine is analyzed in [20] and the torque model of the hydro turbine based on the inner energy loss characteristics is proposed. The method can be applied to calculate the variation of the transient power output.…”