Asymmetric Steady-state Analysis Of A Self-excited Induction Generator Based On A Two-port Network

Compared with synchronous generator,Self-Excited-Induction-Generator(SEIG)has a simple structure,reliable operation,convenient maintenance and transient performance,and many other advantages,is widely used in all kinds of small independent power system,but the existence of the characteristics of low voltage stability makes the SEIG has certain limitation in the practical application.In order to better compensate the disadvantages of SEIG power generation system,it is necessary to carry out in-depth research on its steady-state performance.This paper first introduces the generating principle and conditions of SEIG power generation system,calculates the parameters of the starting motor and rotor according to the open and short circuit test of the motor,and fits the magnetization curve.Considering the variety of connection modes of the system studied in this paper,the various connection modes expand the application range of the motor,increase the flexibility of the system,but increase the difficulty of the steady-state analysis of the system.Parameters to build the system for this,according to the first motor racing,single-phase,threephase load cases of the steady state model,considering the appropriate access to the long and short of shunt capacitor,and explore gradually put forward the more general steady state model of asymmetrical three-phase system,reached a general model to analyze all kinds of connections under the system steady state performance.After the SEIG power generation system is connected to the load,the three-phase equilibrium degree and stability degree of the variables such as voltage,current and frequency of the stator windings are one of the important factors affecting the power supply reliability of the system.Therefore,it is necessary to analyze the performance of the above variables in the steady-state system,which is also of great guiding significance in engineering practice.On the basis of the above model,this paper firstly USES the node admittance method to analyze the steady state operation of SEIG power generation system,solve its external characteristic curve,and analyzes the influence of the excitation capacitance,the load nature and the change of the speed on the external characteristic.Then,based on the symmetric component method and the two-port equivalent method in circuit theory,the two-port sequence network model is derived for the independent SEIG power generation system.According to the variable relationship in the two-port model,the two key variables of output voltage and winding current in the SEIG power generation system are calculated.Finally,an induction motor with rated power of 2.2kw is used to test and verify the voltage and current values calculated by the method described in this paper.It is found that the error of most calculation methods is within the allowable range,which verifies the effectiveness of solving the model demonstrated in this paper.