A Photovoltaic Parallel Inverter System with Shared Capacitor Topology

Abstract

A photovoltaic parallel inverter system with a shared capacitor topology, including multiple photovoltaic grid-connected inverter units, each photovoltaic grid-connected inverter unit is connected in series with a separate AC output LC filter unit to form a branch, and multiple branches are connected in parallel The rear stage of the output end is connected with a shared capacitor unit, and the output end of the shared capacitor unit is connected to the power grid; the LC filter output by each branch, the filter capacitor of the shared capacitor unit after parallel connection and the equivalent inductance of the grid side constitute an LCCL type filter as a whole. structure, since the capacitance of the shared capacitor unit and the filter capacitors of each branch are connected in parallel, the system as a whole is still an LCL type filter structure; the product of the inductance and capacitance of the AC output LC filter unit is equal to the power grid side inductance and shared capacitance The product of the capacitance of the unit, that is, the product of the inductance and capacitance of the inverter side is equal to the product of the inductance and capacitance of the grid side, and the resonant frequency of the LCL filter structure will not change with the number of branches.

Description

technical field [0001] The invention relates to the technical field of photovoltaic parallel inverter systems, in particular to a photovoltaic parallel inverter system with shared capacitor topology. Background technique [0002] At present, the replacement of traditional fossil energy by renewable energy is becoming the main trend of world energy development. In order to solve the needs of economic development and the resulting environmental problems, the installed capacity of domestic photovoltaic power plants has developed rapidly in recent years. Especially in northwestern provinces, large-scale photovoltaic power plants have become the mainstream of development. With the continuous increase of the capacity of photovoltaic power plants, in order to reduce the cost of photovoltaic power generation, the capacity of inverters has increased accordingly, and modular parallel single-unit and multi-unit parallel inverter systems have become a trend of technological development...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the above-mentioned problems in the prior art, the present invention provides a photovoltaic parallel inverter system with shared capacitor topology, which solves the problem of parallel inverters with multiple (module) machines in the prior art as the number of parallel machines (modules) increases. The equivalent parameters of the LCL filter of the inverter system change, resulting in the problem that the system resonant frequency gradually decreases

Images