Synchronization to disturbed AC utility network signals in power electronics applications.

摘要

This thesis presents a digital signal processing system for synchronization to AC utility network signals in power electronics applications. The proposed system is suitable in applications where the signal to which synchronization must be accomplished contains severe disturbances and where the signal frequency and the signal amplitude are variable. The system is based on a multirate phase-locked loop (PLL). The main advantages of the multirate approach are that it relaxes the implementation of the antialiasing filter and it enables one to accommodate the varying amplitude of the input signals. The antialiasing filter, which is in this case a high order bandpass filter, is implemented in the digital part of the system. This feature is achieved by applying the oversampling technique to the input signal. The antialiasing filter automatically adapts to the input signal frequency through the system's variable sample rate operation. The thesis deals with modeling, analysis, control and implementation issues of the proposed system. Nonlinear and linear state-space models and a transfer function model of the system are derived. The system's control aspects are discussed using the derived transfer function model. The system is implemented on a platform based on the Texas Instruments TMS320C31 floating point digital signal processor. Tracking properties of the implemented system are verified with realistic signals such as a sinusoidal signal containing notch type disturbance and noise and an arc furnace voltage signal.