SOCVF feedforward and phase compensation factor switching control method for grid-connected inverter in weak power network

Abstract

The invention provides a SOCVF feedforward and phase compensation factor switching control method of grid-connected inverter under weak power network. The method comprises: The fundamental component of the PCC voltage at the common coupling point is extracted by SOCVF in front of the PLL, Ud and uq generated by PLL are used as voltage feedforward quantities to eliminate the positive feedback branch introduced by voltage proportional feedforward. The phase compensation factor switching method based on impedance modulus judgment is used to compensate the phase of MSFRR. The invention provides acontrol method for grid-connected inverter under weak power network, so as to eliminate the influence of grid impedance on the grid-connected control system of the inverter. The stability of the system is greatly improved, and the adaptability of the system is strong, and the power factor is high, and the ability to suppress the background harmonics of the power network is improved, so that the inverter control system can maintain a high shear frequency, phase margin and gain margin, and the system 's rapidity and stability is enhanced.

Description

Technical field [0001] The invention relates to the technical field of inverter grid-connected control, in particular to a SOCVF feedforward and phase compensation factor switching control method of a grid-connected inverter in a weak grid. Background technique [0002] As the penetration rate of renewable energy such as wind and solar energy continues to increase, it has also brought great challenges to the traditional power grid. Due to the influence of long-distance transmission lines and the leakage inductance of step-up transformers, the line impedance has increased At the same time, because of the continuous switching of power electronic equipment and the existence of nonlinear loads, there are a large number of background harmonics in the power grid. These two factors make the traditional power grid become a weak power grid. Traditional power grids usually use grid voltage proportional feedforward to eliminate grid voltage interference. In the case of weak grids, the pres...

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Problems solved by technology

In order to eliminate the influence of grid background harmonics, the common method is to introduce MSFRR. In the case of weak grid, due to the influence of grid impedance, the bandwidth of the system is reduced. When the bandwidth of the system is smaller than the maximum resonant frequency of the introduced SFRR, the system will be unstable.

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