A control method for single-phase grid-connected inverter based on second-order generalized integrator

Abstract

A single-phase grid-connected inverter control method based on a second-order generalized integrator. The second-order generalized integrator is used to reconstruct the two-phase quadrature fundamental wave current signal to realize the active and reactive components of the current fundamental wave in a synchronous rotating coordinate system. Decomposition of the inverter, and then realize the decoupling control of the active and reactive components of the fundamental wave current; use the reconstructed fundamental wave current signal to realize the observation and control of the harmonics of the inverter output current, and improve the single-phase grid-connected system. Power Quality. The control method is simple and easy to implement, insensitive to the input signal, and satisfies the dynamic and static performance of the system. Compared with the traditional control strategy, the system can still maintain stability when the input signal amplitude drops and the frequency changes, and has a relatively high performance. The value of good engineering practice.

Description

technical field [0001] The invention relates to a control method for a grid-connected inverter, in particular to a control method for a single-phase grid-connected inverter based on a second-order generalized integrator. Background technique [0002] With the rapid development of distributed power generation, the proportion of renewable energy connected to the grid is increasing. Currently, low-power power generation equipment such as single-phase grid-connected inverters are required to have flexible active and reactive power control, and have good grid-connected performance. . As a single-phase grid-connected inverter, the grid information is relatively small, and the calculation of active power and reactive power is not direct enough, which makes the realization of power control difficult. [0003] In the prior art, for the single-phase system control design based on the static coordinate system, the single-phase grid-connected inverter system usually adopts a double-loo...

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Problems solved by technology

[0004] (1) Construct a two-phase quadrature signal based on the delay method. This method uses a delay module that outputs a quarter cycle, which is responsible for generating an output signal that is phase-shifted by 90° relative to the input signal, but this method depends on the input The frequency of the signal, and there is a shortage of poor filtering effect

Therefore, when the frequency of the input signal changes, the time delay of 90° cannot be accurately realized, and the dynamic performance is poor

[0005] (2) The two-phase quadrature signal is constructed based on the differential method. This method has relatively high requirements on the input signal, and is generally applicable to the case of an ideal input signal. If there is a step in the input signal, it will not be able to form a virtual two-phase. In the case of harmonics, since a filtering link must be added to the loop, it also has a greater impact on the dynamic performance of the virtual two-phase

[0006] (3) Constructing two-phase quadrature signals based on Park inverse transform, this method also faces the problem that it is difficult to respond quickly and accurately in the case of non-ideal input signals

However, after passing through the second-order generalized integrator, the filtered high-order harmonics will not be controlled, which will affect the quality of the output signal

[0008] To sum up, the single-phase grid-connected inverter control method based on the synchronous rotating coordinate system needs to construct two-phase orthogonal signals. However, the above-mentioned construction methods have their own defects.

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