Adaptive control techniques for three-phase grid-connected photovoltaic inverters

This chapter presents a framework of model reference adaptive control (MRAC) techniques for three-phase grid-connected photovoltaic (PV) inverter systems with uncertain parameters and disturbances. Such adaptive controllers are employed to achieve two main goals: (i) the asymptotic tracking for the output of a time-varying reference signal by the PV system with high-order dynamics and parameter uncertainties, which cannot be achieved by some conventional control techniques, and (ii) the asymptotic rejection of a practical class of unknown high-order harmonic signal disturbances, which is crucial for desired PV system operations. In this chapter, a full PV inverter system dynamic model is derived, and adaptive control design conditions are verified for such system models. An MRAC based disturbance rejection scheme is also developed for the PV inverter system with parameter and disturbance uncertainties. Desired system performances are ensured analytically and simulation results are listed to verify the result. This study shows the potential advantages of using adaptive control techniques for PV inverter systems, for ensuring desired PV system stability, output tracking, and disturbance rejection properties.