Hierarchical Mode-Dispatching Control for Multi-Inverter Power Stations

摘要

Parallel multi-inverters are widely used in large-scale photovoltaic, energy storage, and other renewable power stations. When a multi-inverter power station is connected to the grid, not only the grid impedance fluctuates but also the inverters are frequently plug-and-play, leading to changes in the structure and parameters of the multi-inverter system and the grid. It could result in small-signal stability or oscillation issue of the whole system. This article proposes a hierarchical mode-dispatching control structure for a multi-inverter power station. In the top control layer, the central controller employs the D-partition-based mode-dispatching method to allocate the number of inverters with different grid connection modes, namely, grid following and grid forming mode, according to the grid-impedance fluctuations and plug-and-play of inverters. In the bottom control layer, the local controller responds to the mode-dispatching commands and applies dual-mode adaptive control strategy to control each inverter in the power station. The proposed control strategy solves the abovementioned small-signal stability or oscillation problem. Its effectiveness is verified by experimental results.

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