Dajun Tao

Calculation of Temperature Distribution in End Region of Large Turbogenerator Under Different Cooling Mediums

In order to study the influence of different cooling mediums on the fluid velocity and the temperature distribution of end parts in the turbogenerator end region, a 330-MW turbogenerator is analyzed. Three-dimensional fluid-thermal coupling analysis model of the turbogenerator end region is given. When the different cooling mediums are used, fluid velocity of fan inlet and pressure values of end-region outlet from the flow network calculation are applied to the end region as boundary conditions, and the losses from 3-D transient electromagnetic field calculation are applied to the end parts as heat sources in the fluid-thermal coupling field. The fluid field and temperature field in the turbogenerator end region are calculated using the hydrogen and air as cooling medium, respectively. Fluid velocity and temperature of end parts in the turbogenerator end region are compared when the different cooling mediums are used. When the hydrogen is used as the cooling medium, comparing the calculated temperature results with the test values, the calculated temperature results match well with test values. These will provide a reference for the ventilation cooling design of large turbogenerator.

Study on Grid-Connection of Powerformer

Grid-connection is the first link of electric energy transport, which will impact generator on safety and electric power grid steady. Powerformer can generate high voltage of the grid level and be connected to the infinite bus directly. In term of the powerformer prototype design feature, the relationship between the grid-connection conditions of generator and slippage voltage in different cases are analyzed in this paper. The effects of phase angle difference on surge current and surge torque during fault-synchronizing process are studied, the varying waveforms are given. And the comparative analysis with conventional machine is also discussed.

Investigation of Primary Dimension Determining Method for High Voltage Cable-Wound Generator

High voltage cable-wound generator, the stator winding of which is made of high voltage cables, is a new type of generator. And its stator structure is different from that of classical generator, so the designment of the primary dimension of high voltage cable-wound generator is not same as conventional generator too. In this paper, the primary dimension determining method for High voltage cable-wound generator is investigated based on the primary dimension determining method of conventional generator, and the specific determining process of primary dimensions of high voltage generator is explained with an example.

Analysis and Calculation of No-Load EFM Waveform for Powerformer

The field circuit coupling time-stepping FEM is proposed to calculate the no-load EMF waveform of salient pole machine, according to the Powerformer prototype, the no-load EFM waveform of Powerformer is calculated, and the effects of different damper windings constraints are considered during calculation, and then the results are compared with the experimental value. It shows that different constraints on damper winding produce different harmonic content in no-load EMF waveform of Powerformer, and the sine distortion rate also changes in some extent, these changes need to be considered in accurate calculation.

Study on the Static Stability of a High Voltage Cable-Wound Generator

High voltage cable-wound generator Powerformer is a new kind generator, which can be connected to the power grid directly. In this paper, the expressions of power characteristics with excitation regulator and power limit of Powerformer are deduced. Combining with the parameters of Powerformer prototype and conventional synchronous generator, the power characteristics variation of Powerformer are obtained considering the effect of excitation regulator by the simulation. Then the power limit of Powerformer and conventional synchronous generator are analyzed contrastively, which proves that the static stability of Powerformer is better than that of conventional synchronous generator.