基于自适应特性的直流微电网双因子下垂控制策略研究

Dual-factor Droop Control Strategy for DC Microgrid Based on Adaptive Characteristics

分布式电源DG(distributed generator)出口线路参数不一致及其出力随机扰动引起了直流微电网负荷功率分配精度下降与网侧电压波动。针对上述问题,计及DG运行暂稳态工况,提出1种基于自适应特性的双因子下垂控制策略。首先,稳态运行时考虑线路阻抗的影响并引入电压调节系数,建立双因子下垂系数稳态分量,在阻抗值未知的情况下即可实现负荷功率的精确分配,同时抬升网侧电压,减小与额定电压的差值;其次,暂态过程中考虑DG出力随机扰动的影响并引入分布一致性迭代算法,建立双因子下垂系数自由分量,可在维持DG均衡出力的情况下快速抑制功率扰动与网侧电压波动,提高系统的稳定性;最后,在PSCAD中搭建直流微电网模型,仿真结果证明了所提策略的有效性。

The inconsistency of line parameters at the outlet of distributed generator(DG)and its random output disturbance lead to a decrease in load power distribution accuracy of DC microgrid and grid-side voltage fluctuation.Aimed at these problems,a double-factor droop control strategy based on adaptive characteristics is proposed with the consideration of the transient-and steady-state of DG operation.First,the influence of line impedance is taken into account during the steady-state operation,a voltage regulation coefficient is introduced,and the steady-state component of doublefactor droop coefficient is established.The exact distribution of load power can be realized when the impedance value is unknown,and the grid-side voltage can be raised to reduce the difference with the rated voltage.Second,the influence of random disturbance of DG output is considered in the transient process,and the distributed consistency iterative algorithm is introduced to establish the double-factor droop coefficient free component,which can quickly suppress the power disturbance and grid-side voltage fluctuation while maintaining the balanced output from DG,thus improving the system stability.Finally,a DC microgrid model is built in PSCAD,and simulation results show the effectiveness of the proposed strategy.