Adaptive Estimation of Higher Order Harmonics from Voltage Source Inverters

Estimation of harmonic distortion from voltage source inverter is an important task for quality control of power grid. The distortion caused by load variation, noises, and switches are unavoidable. Most current results are more hardware-oriented methods and imposing difficulty and inflexibility for controlling the voltage source converter. We proposed an adaptive algorithm to estimate the amplitudes and phases of sinusoidal harmonics given the fundamental sampling frequency of the system. When the switching frequency was also unknown, we determined a time varying updating parameter by algebraically solving a minimal of performance index based on the estimates. The algorithm was verified with signals from a real voltage converter. Once such estimations are obtained, we can reconstruct a working model of voltage inverters by combining the average model and estimated harmonics computationally and thus significantly simplify the modeling and simulation of inverters, which will further facilitate the control design for voltage converter.