Impact of renewable generation resouce on the distance protection and solutions
Venkatesh Chakrapani, Ilia Voloh
Abstract
Distance relays remain primary transmission line protection for more than a century and significantly evolved to handle issues due to changes in transmission network to meet ever-growing demand e.g., protection of series compensated lines, single-pole tripping, and others. Use of the local information to make a trip decision and the backup zone feature makes distance protection an unavoidable choice to protect transmission lines. In the recent years, rapidly increasing amount of the renewable generation, including inverter-based resources (IBR) in the grid is presenting new challenges to the line protection. These new energy resources are behaving quite differently compared with a conventional synchronous generation. Also, each country following its own grid code, i.e., different IBR response for the same fault type and system conditions is possible, which is not the case for the conventional synchronous generation. The proprietary nature of the controller design and the flexibility of operating the inverter in different operating modes makes it difficult to predict and evaluate the actual performance of distance and its supervising elements. In this paper, we discuss the impact of the ‘real-controller’ operating modes and real-world cases on the currents and voltages presented to the distance protection and consequently impact on the characteristics, fault type supervision (FTS), directional elements. We then provide solutions to the problems and introduce the concept of controlled dynamic MHO – an innovative solution for the distance protection in the presence of IBRs and weak sources in general.