A new method for digital PLL control using estimated quadrature two phase frequency detection

In the electric power utility system, PLL control is used to synchronize the inverter voltage to the interconnection voltage. Generally for the single phase system, the PLL control system is constructed with the zero crossing point detection method. In this paper, an estimated quadrature two phase frequency detection method based on the digital controller is proposed which detects the phase and frequency of the utility faster than the zero crossing point detection method. The proposed method is verified by simulation and experiment. In the proposed method, a quadrature two phase signal is estimated from the interconnection waveform. In the simulation, steady-state characteristics and influences of disturbance and harmonics are discussed. In the experiments, the actual performance of the proposed method is investigated.