Quality of Energy in the Photovoltaic Generation through Interaction Between Inverters of Different Manufacturers Connected at Electric Grid

J. Bione Melo Filho, J. Genilson Azevedo
Companhia Hidro Elétrica do São Francisco - Chesf,
Brazil

Keywords: Connected Photovoltaic System to Grid, Inverters, Electrical Voltage

Summary:

This article has purpose to show the behavior of the electric voltage at the Common Connection Point (PCC), in the context of the quality of the energy injected at grid through the interaction between inverters of different manufacturers during a period of microgeneration operation at Grid Connected Photovoltaic System (SFCR), taking as a case study the photovoltaic system installed in the warehouse of Companhia Hidro Elétrica do São Francisco (Chesf) in Abreu e Lima, Pernambuco, with tasks of installation of the analyzer at point of connection of the electric grid, voltage measurement, graphic construction of measurements data, technical analisys, and description of the results of the analysis. The results show a significant analysis, reflecting some impacts on the electricity grid that may occur in presence of Distributed Generation (GD). The supply of electricity to the Consumer Units (CUs) is premised on maintaining the voltage level within the limits acceptable by regulation. According to module 8 of the Electric Power Distribution Procedure in the National Electric System (PRODIST), the critical and precarious voltage values ​​for each nominal voltage level assist in the analysis of the voltage profile provided, indicating its degree of abnormality. GD's increasingly significant expansion can cause technical changes with its impact during the injection of electricity into distribution grids. The interaction between the power injected by the GD units with the grid enables changes in the magnitude of the connection point voltage, which grows as more panels are connected to the grid and also depends on solar incidence and factors such as the configuration of the grid. GD's geographic location and the operation of other voltage control systems, such as switchable capacitor banks and tapped transformers and regulators. Unwanted voltage behavior can affect the regulation of the existing system, even compromising the service life of switched switching equipment. In this context, a PCC electrical voltage profile analysis of a Chesf SFCR was performed, indicating its behavior in terms of power quality, being the inverters the main equipment of the system for the research. The above results have brought some important conclusions. The SFCR Chesf during photogeneration provided an increase in PCC voltage, exceeding the limits established by PRODIST 8, being one of the hypotheses possible voltage drops caused by the output circuit impedance. It was also observed that after the start-up of the SUNGROW inverters, the precariousness and criticality of the PCC voltage increased significantly. Inverters, according to their technology and operating time, can contribute significantly to the increased voltage in the grid connection. The research reflects one of the impacts that GD may have on distribution networks, which are changes in voltage levels. Another reflection refers to the impacts on the loads, being more significant the closer they are to the CCP. Therefore, there is a need for an analysis of the regulation systems by the Concessionaires in order to maintain a balance in the voltage levels, even with the presence of Distributed Generation.