EDP's experience in optimising in-service protection system units

Abstract

Distribution System Operators are increasingly urged by their stakeholders to provide a better and higher quality of service, while minimizing CAPEX and OPEX. With this in mind, EDPD Distribuição (EDPD) developed a programme to optimize its current protection asset base that spans along several generations and technologies, and, consequently, with different levels of protection functions. This programme consisted of an exhaustive revision of all Medium Voltage (MV) protections function settings that comprised a total of 484 substations and switching stations, and over 5100 feeders within the entire mainland Portugal distribution grid. The main goals were to ensure protection relays coordination, guarantee sensitivity for electrically distant short-circuits and minimize voltage dips duration. At first, EDP's Protection and Automation Department used DPlan to conduct systematic short-circuit and protection studies. In order to optimize this process, and reducing man-hours needed, EDPD and AmberTREE worked together to develop improvements within the shortcircuit and reporting modules. With the newly optimized protection settings, EDPD advanced towards in-field confirmation and implementation, resulting in more than 6600 protection function changes, preventing 190 potential coordination failures and reducing the voltage dips duration in 1197 MV feeders. The actual study results' impact on grid operation are now under an assessment stage with an inhouse tool that correlates SCADA and voltage quality monitoring system data. With this work, EDPD expects to improve significantly quality of service and reduce Customer complaints regarding voltage dips and short interruptions by using the existing asset base, while keeping the costs low.