Estimation of tip speed ratio using an adaptive perturbation and observation method for wind turbine generator systems

The main challenge associated with wind turbine generator (WTG) systems is power coefficients vary with operating tip speed ratios (TSR), which are related to wind speed variations. To keep power coefficients at its maximum value, operating TSRs must be held at its optimal value by controlling rotor speeds according to reference rotor speeds at incoming wind speeds using a maximum power point tracking (MPPT) controller. This paper presents a MPPT controller, which is based on a novel TSR observer for estimating TSRs and consequently, reference rotor speeds. It is based on a perturbation and observation (P&O) method, which employs adaptive perturbation step sizes to decrease the time required for estimating TSRs under wind speed variations.