Research On Multi-time Scale Hierarchical Cooperative Control Strategy Of Interface Converter In Microgrid

Micro-grid to power electronic converter as the main body, with a variety of energy storage unit and a load unit, with various control strategies for the support, can realize the power supply and control unit combined with Multi Strategy collaborative work, with flexible multilayer architecture. The main work of this paper is to study the coordinated control between the converter and the control of the microgrid in the microgrid with multi power electronic converters.Firstly, this paper introduces the principle of VSG, and analyzes the relationship between the control and droop, of a VSG score of active power and reactive power parameters design principle, hierarchical control based on the concept of hierarchical control of multi VSG independent microgrid, in ensuring the premise underlying stable control, the the centralized control mode, control in two joined the two compensation control of micro grid frequency and voltage, and the effectiveness of the proposed control strategy is verified by simulation and experiment.Secondly, analyzed the influence of rotor inertia in the equations of motion of the active power and frequency output characteristics, in the existing literature on the moment of inertia of adaptive control based on hierarchical concept, study a modified to two layer control inertia adaptive control. At the same time, from the point of view of parallel VSG stability analysis, the approximate range of the important parameters of VSG is given. The simulation and experimental results show that the improved adaptive control of moment of inertia can be used to adjust the moment of inertia in time scale to achieve good control effect under different operating conditions.Again, unbalanced grid conditions, on the basis of a feasible algorithm is continuous current given the adjustment coefficient, analysis its output characteristics, and the active power and reactive power oscillation amplitude and peak current derived by adjusting the weight coefficient can achieve the control target specific. In view of the active power and reactive power oscillation can also inhibit, and the peak current is not the smallest problem,take a compromise in active power control mode: in the micro network allows small oscillation range under the premise, through the multi-objective optimization algorithm to reactive power oscillation amplitude and peak current minimum, indirectly three control objectives.Finally, grid voltages for active power oscillation of microgrid will make the DC bus voltage fluctuation, and the deterioration of the grid current power quality problems, the hierarchical control theory based on two layer controller on a power converter with multiple active suppression of microgrid rate oscillation control strategy is verified by experiments it can be found that the weight coefficient obtained by the active power microgrid without oscillation, and the adjustment in the weight coefficients in the dynamic process, can realize active power and no oscillation, microgrid reactive power oscillation amplitude unchanged.