Research On The Pitch Control Using PSS And The Setting Of PSS Parameters Based On Induction Wind Generator

With the development of society, the problem of energy shortages is becomingmore and more obvious, so it has become a trend that developing new renewableenergy sources are bound to replace traditional energy sources. Depending on its lowdevelopment cost, clean feature, inexhaustible potential, and mature technology, windpower has been developed rapidly. However，with the large-scale wind farmsconnecting into the power grid, it has a great impact on the small signal stability anddamping characteristics of the power system. This paper proposes an auxiliary controlstrategy for the pitch system to improve the stability of wind power connected into thepower grid.First, this paper gives a detailed description of the basic structure of inductionwind power systems, operating principles and operational characteristics, and buildsthe basic mathematical model including the wind turbine, the induction generator, thedrive system and the pitch control system. It introduces the method of small signalstability analysis and the basic principle of PSS briefly. Second, this paper applies thecompensation characteristics of PSS to the pitch control system of the wind generator.Taking the deviation of the power as the input signal, it provides an auxiliary pitchcontrol for the wind turbine.When power system subjects to small disturbance, someactive damping power correlated with the oscillation is injected into the network fromthe induction generator via the PSS. This will improve the damping of the system tosuppress the oscillations of the power. Based on a single machine and the infinite bussystem, it analyses the oscillation modes and damping characteristics of the systemthrough eigenvalue analysis with the small signal model. By comparing theeigenvalues before and after bringing the PSS into the pitch control system, it isconcluded that PSS can improve the damping of the system. Finally, using the twoareas with four generators as example, a wind farm is added to verify the effect of thePSS. Through the power flow calculation, building the corresponding simulationmodel in Matlab\Simulink, the phase-frequency characteristics of the wind turbine atdifferent wind speed are analyzed, and the oscillation modes existing in the systemare analyzed. According to the phase-frequency characteristics, the parameters of PSSare optimized, thus obtaining a generic parameter for the turbine around the basicwind speed. The simulation results show that the PSS is effectively to restrain the power oscillation, improve the damping of the system, and enhance the stability of thesystem.