Non-frequency coupling phase locking method for accessing high-proportion new energy to power grid

Abstract

The invention relates to the technical field of power electronics, in particular to a frequency-coupling-free phase locking method and control for a high-proportion new energy access power grid. In order to solve the problem that a traditional phase-locked loop easily causes frequency resonance of a new energy grid-connected inverter under a weak power grid and causes complex influence of coupling, the control scheme provides a phase-locked control scheme with a symmetrical structure. According to the scheme, the frequency coupling phenomenon is eliminated fundamentally, phase-locked loop control bandwidth does not need to be reduced, system response does not need to be slowed down, the system model frequency response analysis process is simplified, and stable operation of a high-proportion new energy access power grid is facilitated.

Description

technical field [0001] The invention relates to the technical field of power electronics, and more particularly, to a frequency-free coupling phase-locking method and control for a high proportion of new energy sources connected to a power grid. Background technique [0002] In recent years, with the rapid development of new energy sources and the widespread use of power electronic devices in power generation, transmission, distribution, and power consumption, the grid-connected features of the grid-connected devices and the stability of the interaction with the power grid are affected by the Especially in the context of weak power grids, the related stability problems are more prominent: the interaction between the output impedance of the grid-connected inverter and the output impedance of the grid side is prone to impedance mismatch, resulting in oscillation and instability of the transmission system. [0003] When the three-phase converter adopts the control method based ...

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Problems solved by technology

[0009] 1. When analyzing the stability of photovoltaic grid-connected inverter systems under weak grids, many studies are based on reducing the control bandwidth of the phase-locked loop to achieve stable operation of weak grids, but this method will also lead to slower system response

[0010] 2. The method of reducing the bandwidth of the phase-locked loop reduces the impact of frequency coupling to a certain extent, but for an extremely weak grid environment, further reducing the bandwidth of the phase-locked loop may cause phase-locking failure, and the phenomenon of frequency coupling always exists

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