Last breaker protection strategy based on arrester energy consumption characteristics in light loaded system

Abstract

Original last breaker protection based on arrester energy consumption characteristics might malfunction in light loaded power system. In this paper, we analyzes the relationship between the high side inlet voltage of converter transformer and the AC load, pointing out that the main reason of the arrester based last breaker protection maloperation is that the original protection strategy cannot distinguish light load state from isolation state of the AC line. This paper adds outlet head end voltage and output power to the original criterion, designs an improved one so that it can correctly distinguish what state the AC line and send the right signals for different action status. Simulate and analyze the act of original criterion and improved one in light loaded power system by using the simulation model which is built based on the actual operating parameters of Yunnan-Guangdong UHVDC project, validating the improvement of novel criterion.