Assessment method of single-phase non-isolation photovoltaic grid connected system for parasitic capacitance to ground

Abstract

The invention discloses an assessment method of single-phase non-isolation photovoltaic grid connected system for parasitic capacitance to ground, comprising steps of determining a common mode equivalent circuit, simplifying the common mode equivalent circuit, measuring leakage current of the system to the ground, analyzing the obtained resonance frequency, and estimating the parasitic capacitance. In the common mode equivalent loop, the parasite capacitor size can be calculated by measuring the voltage data and the current data; the common mode voltage is complicated in the component, the measurement is complicated and the measurement accuracy is low. The assessment method disclosed by the invention only needs to measure the leakage current to the ground when the system is working, avoids the voltage measurement in the common mode equivalent loop, and simplifies the complicated measurement process and the signal analysis process in the assessment process.

Description

technical field [0001] The invention belongs to the field of distributed single-phase photovoltaic grid-connected power generation, and specifically relates to a method for evaluating parasitic capacitance of a single-phase non-isolated photovoltaic grid-connected system to ground. Background technique [0002] In recent years, distributed photovoltaic grid-connected power generation technology has developed rapidly; in order to further improve the power generation efficiency of distributed photovoltaic grid-connected systems and reduce power generation costs, grid-connected inverters without transformer isolation are generally used in distributed photovoltaic grid-connected systems . The photovoltaic grid-connected system without transformer isolation will generate a large leakage current to the ground due to the parasitic capacitance of the photovoltaic array and the inverter itself to the ground, which reduces its safety and power generation quality. At present, the size...

AI Technical Summary

Problems solved by technology

At present, the size of the parasitic capacitance can only be estimated according to the instructions of the photovoltaic cell manufacturer, but the overall calculation of the parasitic capacitance of the entire photovoltaic system cannot be carried out. Estimating the parasitic capacitance of the entire photovoltaic system is useful for improving the installation of photovoltaic systems, researching methods of suppressing ground leakage current and It is a good guide to avoid series resonance in the common mode circuit

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