Voltage sag is an inevitable sporadic transient event in the operation of the power grid, which is mainly caused by short-circuit faults in the power system, large-capacity equipment startup, lightning strikes and other events.
For the control and avoidance of voltage sags, electrical technicians have proposed various solutions (reasonable level difference matching of protection settings, release of voltage loss signal, application of anti-sway protection devices, re-closing of relays, etc.), and received good results. effect, but in the application of frequency converters, there is no good solution yet.
Due to the superior speed regulation performance of the frequency converter, it has been widely used by enterprises with a high degree of industrial automation. Inverter devices have relatively high requirements on power supply quality, and the protection setting procedures are closely coordinated. Once a voltage sag occurs, the inverter protection shutdown is often caused, which has a negative impact on continuous production devices.
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