交直流混合微电网运行控制策略研究

摘要

为解决交直流混合微电网中功率波动、交直流系统之间功率平衡、直流侧源荷比相对较大光伏利用率不高的问题，研究了交直流混合微电网并网运行时，在蓄电池的平抑作用下，直流侧光伏发电以恒定的功率通过交流侧并入大电网，提高直流侧光伏利用率。孤岛运行时，蓄电池作为平衡节点，和双向 AC/DC 变换器一起维持整个系统的电压、频率稳定，并实现交、直流系统之间功率平衡的控制方案。最后利用PSCAD/EMTDC软件对系统功率波动、并网运行向非计划孤岛运行切换、孤岛运行向并网运行切换进行了仿真验证，运行结果表明该控制方案能有效平抑系统功率波动，维持交直流混合微电网稳定运行。%To solve the problems of hybrid AC/DC microgrid power fluctuations, power balance between the AC and DC systems, and low PV utilization because of relatively large DC side power load ratio, this paper proposes that in grid-connected operation,under the stabilizing role of the battery, the DC side outputs photovoltaic power into the grid constantly through the AC side to improve the DC side photovoltaic utilization. In islanded operation,the battery as the balance nodes maintains the entire system voltage, frequency stability, and achieves the power balance between the AC and DC systems with the bi-directional AC/DC converter.Finally the PSCAD/EMTDC software is used for the simulation of system power fluctuations, grid-connected operation switching to non-program islanded operation, and islanded operation switching to grid-connected operation, the result shows that the control scheme can effectively stabilize the system power fluctuations and maintain the hybrid AC/DC microgrid stable operation.