Unified mathematical modeling method for open-circuit fault of three-level photovoltaic inverter

Abstract

The invention discloses a unified mathematical modeling method for an open-circuit fault of a three-level photovoltaic inverter, and the method comprises the steps: 1, obtaining a mathematical expression of the direct-current side voltage of the three-level photovoltaic inverter according to the characteristics of the fluctuation of the direct-current side voltage when the three-level photovoltaic inverter is in maximum power point tracking operation; and 2, according to different working conditions and current paths of a main circuit power switch device of the three-level photovoltaic inverter, obtaining a switch function expression under a corresponding fault condition, and finally obtaining a unified open-circuit fault switch function expression and a three-level photovoltaic inverter output phase voltage expression. According to the method, a correct three-level photovoltaic inverter open-circuit fault unified mathematical model can be quickly established in a switching function modeling mode, so that the problems that an existing three-level photovoltaic inverter fault simulation circuit modeling method is large in module number, large in calculation amount, poor in simulation flexibility of switching of different types of faults and the like are solved; and the modeling workload and the simulation working time are reduced.

Description

technical field [0001] The invention relates to a unified mathematical modeling method for an open-circuit fault of a three-level photovoltaic inverter, and belongs to the technical field of photovoltaic operation and maintenance fault diagnosis. Background technique [0002] Photovoltaic inverter is a key electric energy conversion equipment in distributed photovoltaic power generation system. Distributed photovoltaic power generation is distributed geographically, the operating environment is harsh, and the operating conditions are variable. Hazard to system security. PV inverter faults are generally divided into structural faults and parametric faults. Structural faults are open-circuit or short-circuit faults of power devices, which cause changes in the system structure. Parametric faults are parameter drifts of components, such as changes in the characteristics of components such as capacitors, inductors, and transformers. Parametric faults reduce the working charact...

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Problems solved by technology

[0004] In order to solve the shortcomings of the above-mentioned prior art, the present invention proposes a unified mathematical modeling method for the open-circuit fault of a three-level photovoltaic inverter, in order to establish a relatively simple three-level photovoltaic inverter through fault mechanism modeling. Inverter switching fault unified mathematical model, so as to better identify and judge the open circuit fault of three-level photovoltaic inverter, and improve the rapidity of open circuit fault diagnosis, so as to solve the existing three-level photovoltaic inverter fault simulation circuit modeling There are many problems in the method, such as large number of modules, large amount of calculation, and poor flexibility in simulation of different types of fault switching.

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