Phase sequence identification method for three-phase photovoltaic inverters

Abstract

The invention discloses a phase sequence identification method for three-phase photovoltaic inverters, which includes the following steps of a, setting Usa, Usb and Usc as three phases of sampled voltage, initializing USa as the phase A, sampling voltage values of Usb and Usc when the raising edge of the Usa passes through the zero point, sampling once at each set time, and continuously sampling set times; b, adding one to the positive count value Pos_count with the initial value equal to zero if the sampled value of the Usb is smaller than zero and the sampled value of the Usc is larger than zero, and adding one to the negative count value Neg_count with the initial value equal to zero if the sampled value of the Usb is smaller than zero and the sampled value of the Usc is larger than zero during set times sampling; c, after set times sampling, setting the phase sequence of the Usa, the Usb and the Usc to be A, B and C correspondingly if the positive count value Pos_count is equal to the value of the set times, and setting the phase sequence of the Usa, the Usb and the Usc to be A,C and B correspondingly if the negative count value Neg_count is equal to the value of the set times.

Description

technical field [0001] The invention relates to the field of photovoltaic new energy, in particular to a phase sequence identification method of a three-phase photovoltaic inverter. Background technique [0002] Three-phase grid-connected inverter, in the case of no identification of phase sequence, the phase sequence is reversed and grid-connected operation, if the modulation method is unreasonable, it is very likely to cause overcurrent damage to the power device of the inverter; with grid phase sequence identification Finally, when the phase sequence of the three-phase photovoltaic grid-connected inverter is reversed, it can report an error and stop running, or can change the modulation mode of the inverter or the wave-emitting logic according to the identified phase sequence to run normally in grid-connected operation, avoiding the Sequential connection will cause damage to the inverter instead. [0003] At present, the method for identifying the phase sequence of three...

AI Technical Summary

Problems solved by technology

[0008] Since it is to judge the zero-crossing signal, any interference may cause a phase sequence judgment error

like Figure 4 , if there is an interference in the zero-crossing signal of phase C between the zero-crossing signal of phase A and the zero-crossing signal of phase B, the judgment result of this method will judge A, B, and C as A, C, and B, resulting in misjudgment

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