Active damping scheme for multiple LCL inverter resonant coupling

Abstract

The invention provides an active damping scheme for multiple LCL inverter resonant coupling. The active damping scheme comprises a distributed grid-connected power generation system formed by the series connection of a plurality of photovoltaic LCL inverters and a full wave energy metering device. The control structure of the current and active damping control link of each of the LCL inverters comprises an inverter reference output current calculation link, a photovoltaic power front feed reference current compensation link, an inverter output current deadbeat control link and an active damping compensation link. According to the control method of the invention, the harmonic distortion rate of grid-connected total current can be reduced, the metering data reliability of the full wave energy metering device is effectively improved, the specific harmonic amplification interference of inverter output current by the self resonant point of a single inverter filtering link is effectively reduced, the parallel connection resonant coupling among multiple inverter filtering links is effectively reduced, the independence of each inverter output current is ensured, and the interference of the inverter output current by power grid harmonic voltage is effectively reduced. According to the active damping scheme, the safe and stable operation of an inverter parallel system can be ensured.

Description

technical field [0001] The invention relates to an active damping scheme for resonance coupling of multi-LCL inverters adapted to grid-connected metering of distributed power sources, and belongs to the technical field of micro-grid distributed photovoltaic power generation. Background technique [0002] The island microgrid with multiple distributed power sources can use droop control to realize parallel operation of inverters without interconnection wires. When the microgrid is connected to the large grid, the grid-connected aggregated bus voltage of the distributed power generation is supported by the large grid voltage. Each grid-connected inverter system adopts a current control scheme to realize the maximum power tracking control of wind power or photovoltaic. [0003] Deadbeat current control is a control scheme based on the mathematical model of the inverter filter circuit. This scheme only needs to obtain the actual electrical parameters of the inverter system, an...

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Problems solved by technology

[0008] The technical problem to be solved by the present invention is that in order to solve the problem of three kinds of resonance couplings in parallel operation of multiple LCL type inverters in photovoltaic distributed grid-connected power generation technology: self-resonance, parallel resonance and series resonance to the inverter output current quality; at the same time, to improve the reliability of energy metering of traditional full-wave energy metering equipment, an active damping scheme for resonant coupling of multi-LCL inverters is proposed

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