Analysis of incident energy and arc flash boundary behavior in electric power distribution systems

Abstract

The integration of renewable generation systems into electricity distribution grids is becoming increasingly common. New generation plants are commonly connected to electricity grids by modifying their design and operating conditions. Photovoltaic plants are being integrated into large transmission grids, limiting their capacity and altering the conditions for which they were designed. Electricity distribution grids must also cope with the connection of new photovoltaic installations for self-consumption, which can range from a few kW for domestic use to several MW for large industries. For this analysis we focus exclusively on the phenomenon of arc flash (AF) in alternating current (AC) because most AF accidents happen in this type of AC systems, and distribution networks worldwide operate with this type of current, even though they do it at different frequencies. IEEE 1584 TM -2018 has increased the calculation accuracy to determine the incident energy of power systems. Nevertheless, the changing dynamics of power systems due to the connection of new installations and the uncertainty associated with the design parameters has pushed us to develop this study focused on the behavior of AF. This article studies the impact of certain parameters on the calculation of incident energy, as well as on the arc flash boundary (AFB) in an electrical distribution network where a 4 MW photovoltaic generation plant is connected. The most interesting objective of this analysis is to determinate the behavior of the electrical distribution network, considering certain design parameters that may vary throughout its useful life. In particular, the variability of the short-circuit impedance of power transformers and their impact to the distribution network where they are connected has been studied. Other variables such as the opening time of the circuit breakers and the length of the cables are also analyzed, considering a photovoltaic generation plant integrated in the distribution network. Each of the parameters analyzed are extremely important in current power transmission networks. So far, AF analyses do not assume the errors due to the inaccuracy of the data used to parameterize the simulation model. Thanks to this analysis, it will be proven how the variability of certain parameters affects the accuracy of AF analysis in a real distribution network, demonstrating to society the importance of having real, updated and accurate data before proceeding to simulate the system under study.