tailieunhanh - Fundamental and Advanced Topics in Wind Power Part 10

Tham khảo tài liệu 'fundamental and advanced topics in wind power part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Analysis and Modelling of a Self-excited Induction Generator Driven by a Variable Speed Wind Turbine 259 I Iqs Ids Iqr Vcq If iqsdt vcq t 0 Vcq If idsdt vcd t 0 -Idr- Any combination of R L and C can be added in parallel with the self-excitation capacitance to act as load. For example if resistance R is added in parallel with the self-excitation capacitance then the term 1 pC in equation 20 becomes R 1 RpC . The load can be connected across the capacitors once the voltage reaches a steady-state value Grantham et al. 1989 Seyoum et al. 2003 . The type of load connected to the SEIG is a real concern for voltage regulation. In general large resistive and inductive loads can vary the terminal voltage over a wide range. For example the effect of an inductive load in parallel with the excitation capacitor will reduce the resulting effective load impedance Zcff Simoes Farret 2004 . Zeff R j o L- 26 This change in the effective self-excitation increases the slope of the straight line of the capacitive reactance Figure 3 reducing the terminal voltage. This phenomenon is more pronounced when the load becomes highly inductive. 5. Simulation results A model based on the first order differential equation equation 25 has been built in the MATLAB Simulink to observe the behavior of the self-excited induction generator. The parameters used obtained from Krause et al. 1994 are as follows. Machine Rating IB abc rr rs X s X r Xm J Hp Volts Rpm Amps Ohms Ohms Ohms Ohms Ohms 2 500 2300 i773 Table 1. Induction Machine Parameters All the above mentioned values are referred to the stator side of the induction machine and the value of self-exciting capacitance used is 90 micro farads. From the previous subsection it can be said that with inductive loads the value of excitation capacitance value should be increased to satisfy the reactive power requirements of the SEIG as well as the load. This can be achieved by connecting a bank of .