A hybrid maximum power point tracking system for grid-connected variable speed wind-generators

In this paper a maximum power point tracking (MPPT) control system for wind-generator (WG) power applications is presented. The power electronics part consists of a boost DC/DC converter, a DC/AC three phase inverter and two control units: one controlling the boost converter ensuring the MPPT process and one controlling the inverter enabling the grid-connection and power flows control. The presented MPPT controller combines the benefits of two of the most commonly applied trends in the MPPT processes namely: The tracking method based on the optimum power versus speed characteristic and the perturbation and observation (P&O) of the output power method. Simulation and experimental results illustrate that the proposed hybrid control system can cope efficiently with difficulties arising from the separate use of the aforementioned techniques i.e. problems of detuning due to parameter changes or miscalculations encountered in the fixed optimum power characteristic tracking process, and P&O method deficiencies in rapid wind changes or fault recovery. The proposed method is evaluated by using a 2.5 kW experimental prototype.