Interfaces between MV and LV assemblies and power generation facilities in petrochemical plants - a Brazilian experience

The Brazilian Petroleum and Chemical Industry has been facing an ever increasing use of dedicated generation facilities. The use of turbo-generators coupled to gas or steam turbines to partially or totally supply, the electric needs of petrochemical units, has resulted in problems, especially when interconnected with local utility companies. The Switchgear and Control gear Assemblies, both in low and medium voltages, have to face technical and safety key issues when they are connected to electrical system buses with power generation or utility interties. This work has the main objective to present the Brazilian experience with this type of application. This technical paper presents topics related to: high asymmetrical short-circuit currents, system and generator groundings, ferroresonance phenomena in VTs, generator circuit-breaker application, arc-flash energy, special configurations for standard assembly designs, relays with IEC 61850 capabilities. These situations impact the use of the Switchgear and Control gear units. They require special attention from all parts involved in the specification, design, manufacturing and commissioning processes.