Real-Time Energy Balance Control for DC Microgrids with Multi Sources and Multi Loads

In a microgrid architecture with a common DC bus, output fluctuations of generating units and sudden load changes lead to transient power imbalances in the system, resulting in fluctuations in the DC bus voltage and causing over-voltage or under-voltage protection of individual power converters. However, existing schemes are limited by how to capture the transient power deficit across multiple generating units and loads as well as the limited current control bandwidth. This paper first analyses the existing microgrid architectures with common DC bus and establishes a simplified microgrid model. Further, this paper proposes a new real-time energy balance control strategy for microgrids with multiple source load nodes under common DC bus. Firstly, the DC bus voltage is sampled and taken as raw data to predict the voltage variation in the next control cycle. Then, the predicted voltage fluctuation value serves as a power compensation feed-forward command. Finally, the compensation takes place using a deadbeat current predictive algorithm. This scheme enables the overall feed-forward of power deficit among multiple source loads, and effectively solves the problem of transient power imbalance. The effectiveness of the proposed scheme is finally verified by simulation in this paper.