The invention discloses a device and method for giving an early warning about a main
transformer DC magnetic bias event. The device comprises a plurality of GPS
clock modules, a plurality of shunts, aplurality of AC / DC synchronous acquisition modules, a
data monitoring module, a
big data analysis module and an early warning module; a main
transformer neutral point ground loop in each monitoring point is connected in series with a shunt; each shunt is provided with a wiring terminal for sampling an AC / DC
signal flowing through the main
transformer neutral point; each shunt and the GPS
clock module corresponding thereto are electrically connected to an AC / DC synchronous acquisition module; each AC / DC synchronous acquisition module communicates with the
data monitoring module through a communication module; the
data monitoring module is connected with the
big data analysis module; and the
big data analysis module is connected with the early warning module. The device can analyze the
synchronism of DC fluctuations at multiple monitoring points, identifies a DC magnetic bias event, quickly identifies the type and
hazard level of the DC magnetic bias event, locates a
harmonic source, and provides a decision basis for grid operators and maintainers.