On the Fault Behavior of Inverter Controllers: Impact on Protective Relaying

Integration of inverter interfaced distributed gen-erators (1IDGs) in distribution networks has prominently in-creased the reliability and resiliency of the power networks along with the environmental benefits. At the same time, such integration imposes unique challenges for the power system protection. The fault response of IIDGs is dictated by their control structure and current limiting algorithms, and hence it is significantly different than linear short circuit models of synchronous based distributed generators. This unpredictable fault behavior of IIDGs creates various protection issues to the conventional protective relaying. This article unveils the short circuit behavior of IIDGs with different control algorithms and current limiters employed. The fault response of each inverter is first tested individually on a three-bus network, then in unison with other inverters having different controller on a CIGRE network. Distinct fault behavior of various inverter controllers require serious attention to either modify or replace the available protection schemes.