A Harmonic Phase Reshaping Control Strategy for Minimizing Secondary Harmonic Injection in DC Microgrids

The secondary harmonic sources in DC microgrids exhibit dispersity and unpredictability, posing significant challenges to the capacity design of filters. Existing filtering methods overlook neglect the potential for harmonic cancellation, leading to an excessive reliance on large-capacity filters. This paper proposed a harmonic phase reshaping strategy that maximizes harmonic cancellation by adjusting the harmonic phase, thus minimizing the harmonics injected into DC microgrids. Firstly, a optimal harmonic phase generator is developed that iteratively generates reference phases by following the negative gradient direction of the total harmonic amplitude. Subsequently, a harmonic phase tracker is introduced, which adjusts the voltage phase to align the harmonic phase with the reference phase. This method can reduce the total harmonics to zero or below the level of the largest single harmonic, thereby significantly decreasing the configuration capacity of the filter. Simulation results in RTLAB show that the proposed method can achieve optimal harmonic cancellation, effectively reducing the filtering burden in DC microgrids.