Study On Mathematical Model And Transient Parameter Of Pumped Storage Units Based On Time-Stepping Finite Element Method

In order to study the effects of core saturation to steady and transient reactance of pumped storage units, the field-circuit-motion coupled time-stepping finite element (FEM) model which is based on unit machine is built in this thesis. Based on this model, the three-phase sudden short-circuit operating conditions is simulated to study the response of power system and proposed new methods for the calculation of steady-state and transient parameters. This study provides an theoretical principle for building the pumped storage units model for power system analysis and electromagnetic calculation of machine. The main works are as follows:1. The field-circuit-motion coupled FEM model of pumped storage units based on unit motor is built, it can greatly reduce the units and nodes of multi-polar pumped storage units model, and shorten the calculation time.2. The rotation rotor steady parameter calculation method (ie, the stator and rotor core reluctance rates in every calculation step of the finite element model are kept unchanged, plus direct axis current on armature winding, make field winding and damper winding open, rotor revolution, every step a reactance value can be obtained, then, the maximum value is the direct-axis synchronous reactance and the minimum is the quadrature-axis synchronous reactance.) is built to obtain the reactance curve and field figure and the steady state reactance in generator and motor working conditions. Simultaneously, the rotor fixed steady parameter calculation method (ie, the stator and rotor core reluctance rates are kept unchanged, make+d axis coincides with+A axis, make field winding and damper winding open, plus direct-axis current on armature winding, then the direct-axis synchronous reactance is obtained, and plus quadrature-axis current on armature winding, then the quadrature-axis synchronous reactance is obtained) is built to calculate steady state reactance. The calculated values of rotor rotation method and rotor fixed method and the design are all less than5%of the difference. And then, the saturated synchronous reactance in different load and power factor of generator and motor working conditions are calculated by rotor rotation method and rotor fixed method, the regularity is analyzed.3. The parameter calculation method of combining frozen magnetic permeability method to calculate the leakage reactance of stator and rotor windings and armature reaction reactance under three phases sudden short status, and obtain the transient parameters by substituting the values into transient parameter definition formula is built (for short frozen magnetic permeability parameter calculation method). Simultaneously, the three-phase short circuit current is obtained by the envelope method, and through the short circuit current parameter identification, the transient parameters under three phase sudden short status are obtained (for short envelope method). The two calculation methods are used in steady state, transient, sub-transient and time constant calculation of Xiang shuijian pumped storage machine. Finally, the two calculation methods are used in the6poles anti-mounted hydro-generator, and compared with the experimental results, the effectiveness and feasibility of the frozen magnetic permeability method are verified.4. The sudden three-phase short-circuit current waveforms of pumped storage machine of taking into account the motor speed changes or not are close. And the sudden three-phase short-circuit current waveforms of anti-installed hydro-generator of taking into account the motor speed changes or not are close, and the short circuit current waveform which consider speed changes is closer with the measured waveform, indirectly reflect the accuracy of the calculation of electromagnetic torque. It provides a theoretical foundation for structure design and dynamic parameter research of the pumped storage machine.