Hierarchical coordinated control of DC microgrid with wind turbines

Control and operation of a DC microgrid under various operating conditions are investigated in this paper. A wind turbines based DC microgrid configuration is used to accurately describe different operation modes firstly. For a DC mcrogrid system, an abnormal DC voltage caused by power fluctuations can disrupt normal operation or even cause the whole system to collapse. Therefore, to improve the system stability, this paper proposes a hierarchical coordinated control strategy according to the DC voltage variation range. Under any condition, there must be at least one DC terminal being responsible for DC voltage control. On this basis, the control method for each power electronic converter is described under different control levels. Finally, the validity of the proposed hierarchical control strategy is demonstrated by simulations on a DC microgrid with wind turbines using MATLAB/Simulink in different operation modes, considering various operating conditions, such as variations of wind speed and load, AC grid fault, and load shedding.