A real time DSP based differential protection of Low voltage busbar

Medium and Low voltage busbar is important equipment in the electrical power system, and its protection demands simple, reliable, economic & sensitive relaying scheme. This paper presents design, implementation and testing of low voltage busbar relaying scheme in laboratory environment using TMS320LF2407A Digital Signal Processor (DSP). Current differential algorithm is designed based on the DSP platform which can reduce large amounts of calculation, expedite the protection´s trip and reduces the hardware requirements. Authors have developed a laboratory prototype of the three-phase busbar system containing 3-phase bus, current transformers, line components, fault switches and DSP trainer kit. Experimental results are provided to verify the effectiveness of the proposed scheme. The scheme provides stability against external faults, sensitivity towards high resistance internal faults and better reliability in discriminating in-zone and out of zone faults.