Overcurrent and Differential Protections for Power Substations Using Three-Winding Transformer

Abstract

This paper presents a method to determine parameters of overcurrent and differential protections for power substations using three-winding power transformers. Active current threshold and time and working area are shown in this paper to help to calculate and set above relaying protections. An experimental model depicted a relaying system for a power substation using two three-winding power transformers is built to serve education training. It has a complete system structure of relaying protection, including a Arduino Mega 2560 processor, measuring system emulated by variable resistors, real time module and SD card module to record fault events, relays to represent on/off states of circuit breakers. Parameters of relaying protections can be adjusted in the processor to customize the its operation of system and make a visual view about its responses in real working process of power substations. Results received from the model showed the accurate setting method and its meaning that help to verify theory and make clear about relaying protections in education training. Keywords: Overcurrent protection, differential protection for power transformer, relaying protection for power transformer, setting parameters for relaying protection, active current threshold, working time.