Analysis Of Ac Asymmetrical Fault On Dc Control System In Hybrid Ac/Dc Microgrid

Compared with the individual AC microgrid and DC microgrid, hybrid AC/DC microgrid is more suitable for high permeability renewable energy access to the power grid. Hybrid microgrid contains a lot of sensitive DC load and all kinds of distributed generations (DC). The harmonic disturbance produced by the AC fault will not only affect the DC line, but also affect the control system of the DC, resulting in the violent fluctuation of the output power of the DC, which is not conducive to the stability of the hybrid microgrid. Firstly, the influence of disturbance (zero sequence component and negative sequence component) caused by AC grounded fault on voltage and power of the DC system is analyzed in depth. Secondly, the action mechanism of the zero sequence component and negative sequence component to the DC control system on DC side is studied, and then the calculation method of the internal loop current reference containing the disturbance component is given under the typical control strategy of DC. Finally, a hybrid microgrid fault equivalence model is built on the PSCAD/EMTDC software in order to verify the correctness of the aforementioned theoretical analysis.