Influence of excitation system adjustment unit on dynamic stability of generator system

Abstract：Excitation system adjustment unit plays an active role in adjusting generator's external characteristics, and simultaneously affects the dynamic stability of generator.The generator's grid-connected model was studied according to Thevenin theorem.The relationship between generator stator current and equivalent potential and the relationship between generator stator current and phase angle were analyzed.The impact on measured voltage was discussed after the introduction of adjustment unit through vector diagram.The simulation model of one machine-infinity bus system with adjustment unit was established by using MATLAB.The influence of different adjustment coefficient on power system dynamic stability was explored.When the power system met static stability, the system met dynamic stability either as adjustment coefficient was positive.When adjustment coefficient was negative, the bigger the absolute value of the adjustment coefficient was, the easier the dynamic instability of the system would occur, and the greater the output active power of the generator was, the easier the dynamic instability of the system would occur.

Keyword：adjustment unit;dynamic stability;excitation system;power flow calculation;low frequency oscillation;