Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers
Title Leakage current Equivalent circuit Model and Analysis of PCS for Distributed power
Authors 서정진(Joungjin Seo) ; 차한주(Hanju Cha)
DOI https://doi.org/10.5370/KIEE.2021.70.11.1691
Page pp.1691-1696
ISSN 1975-8359
Keywords Leakage current; Common-mode Voltage; Equivalent circuit; Parasitic capacitance
Abstract Due to continuous environmental problems around the world and an increase in energy consumption, interest in solar power, wind power, and hydropower is increasing. Among them, photovoltaics is the most used in industries and homes because it is easy to repair and can be used for a long time. In photovoltaic PCS, parasitic capacitance is generated between the photovoltaic module and the ground due to the installation structure of the photovoltaic module. This parasitic capacitance, VCM, which is a common mode voltage generated by switching of PCS, is applied to CP, and leakage current occurs. In this paper, the common mode voltage characteristics at three-phase three-level, and three-phase two-level were compared. Proposed an equivalent circuit that was equalized from unaffected by grid impedance the point of view of the common-mode by dividing it into a transformerless type PCS connected to the grid ground and a transformer type PCS applying a transformer. The validity of the proposed equivalent circuit was verified by constructing a three-phase three-level PCS and comparing the equivalent circuit using the experiment measurements and PSIM. In the transformerless PCS, the leakage current is equivalent to 1.13A in the equivalent circuit and 1.14A in the experiment. In the transformer type PCS, the equivalent circuit is 68mA and the experiment 70mA. In addition, for the validity of the proposed equivalent circuit, FFT analysis of leakage current, which is the switching frequency, was performed.