A Complete Electrical System Study for A Refinery with Major Expansion

A full electrical system study for a refinery with major expansion is reported. The expansion added two cogeneration gas turbine generators (GTGs) and one steam turbine generator (STG) to the system that had only one STG before. A new 22 kV gas-insulated switchgear (GIS) lineup was installed with a current limiting reactor added to the bus tie. The plant load is 77 MW, onsite generation is 65 MW, and 12 MW power is imported from the grid. Due to the new generators, a complete system study to size equipment, adjust protection settings and ensure system stability needed to be carried out. The scope of this system study project includes load flow, short circuit, protection and coordination, motor starting, and transient stability. The study lasted and covered project stages from For Review (FR) and For Design (FD) to For Construction (FC). The detailed system study helped the engineering, procurement, construction (EPC) contractor and refinery owners validate system design and protection under various conditions. The paper shares experiences of selecting study scenarios, identifying key parameters, validating system models, utilizing computer software features, analyzing study results, and proposing recommendations.