Baojun Ge

The Excitation System Simulation of Huge Hydro-generator

Taking the example of 1000 MW hydro-generator, the mathematical model of the huge hydro-generators excitation control system is analyzed and the automatic voltage regulator (AVR) using PID control mode as the main research content of the excitation control system is researched. The simulation model is constructed in Matlab/Simulink environment. Analyzing the simulation result, the system short-circuit fault has a greater impact on the hydro-generator using self-excitation method. When the fault is removed, adjusting generator excitation system contributes to the stable operation of hydro-generator and power system.

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.

Analysis of Load Characteristics for a 1000MW Hydro-Generator within Considering Saturation

Through the finite element method, nonlinear load characteristics for a certain 1000MW hydro generator within considering saturation are studied based on theoretical analysis. The characteristic curves are relationship between resultant current and air electromotive force. To obtain a series of saturated nonlinear load characteristic curves under varied conditions, the different operation conditions, such as keeping field current and power angle constant, keeping ratio of d axis current to q axis current of stator constant, keeping ratio of field current to q axis current of stator and keeping power factor constant, respectively are analyzed in this paper, the results reveal complexity of nonlinear load characteristic and provide the theoretical basis for foundation of the model and operation of huge hydro-generator within considering the saturation Keywords-component; nonlinear load characteristics; FEM; saturation; 1000MW hydro generator

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.

Study on Electrical Braking of Huge Hydro-generator

In this paper, based on the relationship of the losses and rotor speed of generator, the braking time formula with the braking mode of the hydro-generator stator three-phase short-circuit is obtained within considering the stray losses. The breaking times at different braking currents and different input speeds about a 1000 MW hydro-generator are calculated. The results prove that it is feasible and superior to brake the huge hydro-generator with the mode of stator three-phase short-circuit, and also give some references for the actual operation of generators in the future.

Study on Static Power Characteristic of Huge Hydro-Generator

In this paper, based on electrical machinery classical theory,the mathematical model of static steady operation for the huge hydro-generator is established, and the expressions of the static power characteristic and the static steady power limit are deduced. Reference on the design parameters of 1000MW hydro-generator and 700MW hydro-generator, the change laws of the static power characteristic and the power limit are obtained with simulation. Keywords-huge hydro-generator; static steady power limit; power characteristic;

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.

Dynamic Simulation of Powerformer Under Loss of Excitation

Powerformer is a kind of new high-voltage generator. The simulation method of dynamic simulation analysis of Powerformer under loss of excitation base on MATLAB/simulink is proposed. Simulation model of exciting windings open circuit based on simulink is built, and simulation result is analyzed. The changing regular pattern of exciting electric current, stator current, stator terminal voltage, active power and reactive power are obtained through simulation. If Powerformer can be come into stabilized asynchronous running condition after loss of excitation, that offers time to clear fault. This reduces expense caused by its step-out and stoppage, and further improves operation reliability of generators and the electric power system.

The Simulation Analysis of Leading Phase Operation of Powerformer

In order to study the leading phase operation performance of Powerformer, a simulation model of Powerformer is proposed in SIMULINK/SPS. The operation of Powerformer from steady-state to leading-phase state is simulated in a single-machine infinite-bus system. The simulations of stator voltage and current, power-angle and power factor under leading phase operation of Powerformer are obtained, and the depth of leading phase operation of Powerformer is analyzed. Comparison between simulation results and experimental results shows they are consistent.