Method for using one-phase photovoltaic grid-connected inverter to detect network voltage phase

Abstract

The invention relates to a method for using a one-phase photovoltaic grid-connected inverter to detect a network voltage phase. The method for using the one-phase photovoltaic grid-connected inverter to detect the network voltage phase is characterized by comprising the following steps of (1) carrying out filtering processing on collected network voltage signals, removing higher harmonic except direct-current components and fundamental frequencies through filtration, and obtaining a signal Valpha; (2) carrying out 90-degree phase shifting on the obtained signal Valpha, and generating a signal Vbeta, namely, generating a set of orthogonal signals; (3) carrying out d-q conversion on the obtained orthogonal signal Valpha and the obtained orthogonal signal Vbeta according to an estimation angle theta' of a power grid, and obtaining a Vd and a Vq, wherein the initial value of the estimation angle theta' of the power grid is set to be zero, the operation value can be updated through the step (4) and the step (5), and thus the estimation angle theta' can reach the real network voltage phase after the transient state process ends. The method for using the one-phase photovoltaic grid-connected inverter to detect the network voltage phase has the advantages that interference of the harmonic in the collected network voltage signals can be removed through filtration, signals, with the direct-current components, in the collected network voltage signals can be removed through filtration, and higher phase locking accuracy can be achieved.

Description

technical field [0001] The invention relates to a method for detecting grid voltage phases by using a single-phase photovoltaic grid-connected inverter. Background technique [0002] At present, most single-phase (photovoltaic) grid-connected inverters use zero-crossing detection to track the grid voltage phase, which has poor anti-interference performance. In addition, there is also a single-phase phase-locked technology based on a synchronous coordinate system based on a three-phase phase-locked loop. This type of method needs to construct a pair of orthogonal signals. Currently, the methods commonly used to construct orthogonal signals include the delay method using array storage and A phase shift of 90° is realized based on a generalized second-order integrator. Among them, the delay method only needs to construct an array, which has a simple structure, but because it cannot filter out the harmonic interference in the collected grid voltage signal, the phase-locking acc...

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Problems solved by technology

Among them, the delay method only needs to construct an array, which has a simple structure, but because it cannot filter out the harmonic interference in the collected grid voltage signal, the phase-locking accuracy is poor; while the phase-shifting method based on the generalized second-order integrator It cannot solve the problem of poor phase-locking accuracy when DC components appear in the collected grid voltage signal

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