直流微电网运行控制策略

Operation and Control Strategy of DC Microgrid

以光伏发电、储能装置、网侧变换器、直流负荷构成的直流微电网为研究对象,考虑孤岛和并网2种运行方式,设计系统4种工作模式,研究该微电网的运行控制策略。提出锂电池自适应调节下垂系数的控制策略,优化不同条件下电池的输出功率,提高电池和系统运行效率;光伏变换器采用变步长电导增量法进行最大功率跟踪;网侧变换器采用基于前馈解耦的电压电流环控制。该系统整合光伏发电和储能控制技术,能够在2种运行方式和4种工作模式间平滑切换,可以维持直流母线电压恒定,实现能量最优利用和系统稳定工作。实验结果验证了上述控制策略的可行性。

Taking the DC microgrid composed of photovoltaic （PV） generation, energy storage devices, grid-side converter and DC load as the object of research and considering two operating modes of islanded operation and grid-connected operation, four operating modes for DC microgrid are designed and the operation and control strategy for such a DC microgrid is researched. A control strategy, which adopts lithium cell to adaptively adjust the droop coefficient, is put forward to optimize the output power of the cell under different conditions and enhance operating efficiencies of both the cell and the microgrid. The optimal power tracking of PV converter is implemented by variable step-length incremental conductance and the feed-forward decoupling based voltage and current loop control is applied in the grid-side converter. In the proposed microgrid the PV generation is integrated with energy storage control technology, so the switching between the two operating modes as well as the switching among the four working modes can be smoothly carried out, thus the DC bus voltage can be kept constant, and the optimal utilization of energy and stable operation of the microgrid can be ensured. Experimental results show that above-mentioned control strategy is feasible.