Method for controlling stability when microgrid grid connection switches to island operation mode

摘要

Disclosed by the present invention is a method for controlling stability when a microgrid grid connection switches to island operation mode, i.e., collecting respective electrical quantities of a microgrid and an interconnection wire by means of a microgrid central controller and a rapid measuring and control unit, and obtaining the real-time operating state of the microgrid by receiving an instruction from a high-level system; in case of a planned island, calculating the real-time load and power source output of the microgrid system, and determining whether a source and load are balanced; otherwise, when the system satisfies island criteria, switching a primary power source from a PQ operation mode to a V/f operation mode, and turning off a PCC switch, then determining whether the system operates normally; if the system is abnormal, immediately cutting off a faulty circuit when the faulty circuit is detected, and re-starting determination; if the system is normal, determining whether a source and load are balanced within the microgrid system; if the source and load are unbalanced, calculating the quantity of power imbalance, adjusting the output of stored energy, and then determining again whether a source and load are balanced; if the source and load are unbalanced, performing load reduction at low voltage/low frequency, and determining again whether a source and load are balanced. The present invention can implement a simple manner of detection, having good stability.