A current reference-enhanced strategy endows the GFC in DC microgrids better dynamic response

Abstract

Abstract The constant voltage strategy (CVS) is more suitable for the small-capacity dc microgrid applications to form the dc bus voltage because it can eliminate the steady voltage deviation. However, its dynamic performance is slowed down by the integrator in the voltage loop and negatively influenced by the load steps. Some advanced methods have been conducted in the literature. However, their principle is to increase the system bandwidth, which is limited because the bandwidth is generally designed about one-tenth of the switching frequency and cannot be increased infinitely. This work pays efforts to increase the gain within the system bandwidth to accelerate the transient response and simultaneously eliminate the influence of the integrator. Therefore, the non-integrator disturbance observer-based (NIDOB) strategy is proposed in this work, and it can feed the load current into the current reference to replace the output of the integrator. Compared to the traditional and non-integrator directly-feedforward (NIDF) strategy, it has a better dynamic performance. Compared to the bandwidth-increased strategy, it does not introduce more noise. The theoretical analysis and experimental results prove its advantages.

Keywords

• DC microgrids
• Non-integrator control
• Current reference enhancement
• Dynamic performance
• Load disturbances