Protection coordination assessment and improvement of electrical network of an industrial complex in connection to power grid: An experience report

Protection of electrical network of an industrial complex is a challenging task in particular in connection to the power grid. This paper is focused on this challenging task and reports on the experience of protection coordination assessment and improvement of electrical network of South Pars Gas Complex (SPGC) and in particular the third south Pars refinery. Today South Pars is the economic hub and heart of the gas and petrochemical industry in Iran. The continuous and stable production of gas from the South Pars Gas Field is very important. In order to supply power to the third south Pars refinery four gas turbine generators (GTG) each with a capacity of 41.1MW and two emergency diesel generators (EDG) each with a capacity of 4.5 MW have been installed. In addition to this, one external line to connect the plant to the power grid is considered. Now the third refinery as an island electrical network operates independently from the power grid and provides energy needs of the refinery process and utility units. By connecting the refinery's electrical network to the power grid short-circuit current value increases. If an error occurs on the internal network when the refinery is connected to the power grid, the fault current will be higher compared to when the Refinery works in island mode. This is because current is also injected from the power grid to the faulty point. In this paper, the third south Pars refinery protection coordination in connection to the power grid will be assessed. The ETAP software will be used for the simulation. While the paper reports the practical experience in relation to this particular case study, the approach and experience helps to face the practical challenges in similar projects.