Three-phase phase-locked loop method appropriate for photovoltaic grid connected low voltage ride through

Abstract

The invention provides a three-phase phase-locked loop method appropriate for photovoltaic grid connected low voltage ride through and relates to the field of solar power generation power supply, in particular to a three-phase phase-locked loop which has a function of low voltage ride through. The three-phase phase-locked loop method appropriate for the photovoltaic grid connected low voltage ride through solves the problems that an existing phaselock technique needs to consider influences of zero wander, and an existing detection method does not consider influences brought by measuring voltage deviation on voltage detection. The three-phase phase-locked loop method appropriate for photovoltaic grid connected low voltage ride through includes a first step of inputting network voltage v to a second-order orthogonal signal generator and outputting two sinusoidal signals v' and qv', wherein phases of the two sinusoidal signals differs by 90 degrees; a second step of calculating the signals v' and qv', obtaining line voltage amplitude VRMS, and converting the line voltage amplitude VRMS into phase voltage amplitude VP; a third step of inputting the signals v' and qv' into the phase-locked loop, locking a line voltage phase angle theta1, detecting the line voltage phase angle theta1, and converting the line voltage phase angle theta1 into phase voltage phase angle thetap; and a fourth step of conducting grid connection according to the phase voltage amplitude VP and the phase voltage phase angle thetap by means of an inverter current control strategy, and achieving the photovoltaic grid connected low voltage ride through. The three-phase phase-locked loop method appropriate for the photovoltaic grid connected low voltage ride through is appropriate for photovoltaic power stations.

Description

technical field [0001] The invention relates to the field of solar power generation and power supply, in particular to a three-phase phase-locked loop with a low-voltage ride-through function. Background technique [0002] In recent years, with the expansion of the installed capacity of photovoltaic equipment, the proportion of solar power supply is increasing. Therefore, it is necessary to consider the impact of various operating states of photovoltaic power plants on the stability of the grid when the grid fails. The single-phase drop and double-phase drop in the three-phase unbalanced fault of the power grid have more and more serious impacts on photovoltaic grid connection. At present, as the power generation of photovoltaic power plants increases year by year, once these failures will lead to a large decrease in the output active power of the photovoltaic power plant, increase the difficulty of the recovery of the entire system, and may even aggravate the failure, causi...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problem that the existing phase-locking technology needs to consider the influence of the zero point drift and the existing detection method does not consider the influence of the measured voltage offset on the voltage detection, a low-voltage grid-connected photovoltaic system is proposed. Three-phase phase-locked loop method for voltage ride-through

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