Quick off-grid detection method for energy storage inverter

Abstract

The invention relates to a quick off-grid detection method for an energy storage inverter, which can detect mains supply signals and judge whether a waveform abnormal state appears and further providea basis for quick off-grid switching for the energy storage inverter. The method comprises steps: the mains supply signals are sampled to acquire sampled signals; after each time of sampling, based on the voltage and the phase of the sampled signals and in combination of a calculated high-voltage waveform detection counter threshold, a low-voltage waveform detection threshold, a preset voltage detection threshold, a voltage judgment threshold and various time thresholds, whether the mains supply signals are abnormal is judged. The problem that the existing off-grid detection consumes over long time can be overcome, whether the mains supply is subnormal can be quickly judged, and a favorable advantage is provided for a subsequent off-grid action of the energy storage inverter. The method has good adaptability, error detection on abnormality of the mains supply in a normal specific harmonic injection condition does not happen, and the accuracy is high.

Description

technical field [0001] The invention belongs to the field of energy storage inverters, and in particular relates to a detection method adopted by an energy storage inverter with an off-grid function when the commercial power is abnormal and needs to be quickly switched to an off-grid mode. Background technique [0002] Commonly used on-grid and off-grid systems are mainly divided into UPS and EPS, among which UPS is divided into online type and backup type. The online type usually rectifies the mains power into DC and then outputs the inverter voltage through inversion to supply power to the load. When the mains power is interrupted, the online UPS can be seamlessly switched by the battery; the backup UPS is to detect When the mains voltage is normal, connect the mains to the load terminal through the bypass. When the mains voltage is abnormal, you need to cut off the bypass to obtain the off-grid voltage from the battery. This process will cause a short-term interruption of...

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Problems solved by technology

[0003] The usual detection method is to complete the detection by means of the phase of the mains zero-crossing point or the effective value of the mains power in one cycle, but these methods will cause the detection cycle to be at least one cycle of the mains power, which will greatly lengthen the off-grid switching time and affect the load. powered by

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