Order reduction method for LCL-T module of photovoltaic power generation system

Abstract

The invention relates to an order reduction method for an LCL-T module of a photovoltaic power generation system, which comprises the steps of in the case that an isolation transformer is unsaturated, building a mathematical model based on the LCL-T module of the photovoltaic power generation system, acquiring transfer functions between input voltage of a filter and output current of the filter and between the input voltage of the filter and primary side current of the transformer, and introducing weighted feedback current so as to realize zero and pole cancellation and achieve the purpose of simplification; and in the case that the isolation transformer is saturated, solving a transfer function between the input voltage of the filter and primary side output current of the transformer in consideration of primary and secondary side resistance and excitation resistance of the isolation transformer, and reducing the high-order LCL-T module into a first-order system with series connection of an equivalent resistor and an equivalent inductor by adopting a Routh approximation method of a high-order system based on the Routh stability rule; and carrying out Bode diagram verification through PSCAD / EMTDC modeling and simulation and MATLAB data processing, and comparing the detailed model with the equivalent model result, thereby being capable of effectively reducing the simulation time and improving the simulation accuracy.

Description

technical field [0001] The invention relates to the technical field of photovoltaic grid-connection, and relates to an order reduction method for LCL-T modules of a photovoltaic power generation system. Background technique [0002] As the penetration rate of photovoltaic power generation systems increases, the network system structure becomes more and more complex. The higher model order of photovoltaic power generation systems leads to a larger amount of calculation, which brings problems such as model validity, data correction, large memory usage and long simulation time. And other issues. Therefore, it is necessary to study an equivalent model to solve the problems of large memory usage and long simulation time. The LCL-T module is a module composed of an LCL filter and an isolation transformer T. The step-down process of the LCL-T module in a photovoltaic power generation system needs to consider the saturation and non-saturation of the transformer. The high-order sys...

AI Technical Summary

Problems solved by technology

[0002] As the penetration rate of photovoltaic power generation systems increases, the network system structure becomes more and more complex. The higher model order of photovoltaic power generation systems leads to a larger amount of calculation, which brings problems such as model validity, data correction, large memory usage and long simulation time. And other issues

Therefore, it is necessary to study an equivalent model to solve the problem of large memory usage and long simulation time

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