Optimisation of the selection and use of protections in numerical controlled substations. Application in Belgium

Substation secondary equipment is today exposed to important technical innovations. Since the advent of the microprocessor in numerical protection and control, this technology has become common place in modern substations. Selecting protection equipment for numerical controlled substations leads one straight to the numerical relays. This report illustrates the potential offered by digital protection in a numerical controlled substation. An illustration of the growing optimisation of protection techniques is given by the 36 kV substation of Langerbrugge. This important supply station in the Belgian power distribution system is supplied by three 110 MVA transformers 150/36 kV, two turbo-generators of 20 MVA and 40 MVA, and a turbo-jet generator of 18 MW, and consists of a double busbar system with a bus coupler and 24 feeders. More precisely, this 36 kV substation will be equipped with digital feeder protection based on distance or overcurrent algorithms and digital busbar protection