Impact analysis of recovery ramp rate after momentary cessation in inverter-based distributed generators on power system transient stability

The global increase in the use of solar photovoltaics and wind turbines has led to a rapid increase in the penetration level of inverter-based distributed generators (IBDGs). Until recently, the operation modes of IBDGs under abnormal power system conditions were not a major concern owing to the small number of IBDGs used in power systems. However, several events have indicated that the momentary cessation (MC) mode of an IBDG can eventually deteriorate the stability of power systems. Among the various parameters that define the MC mode, the direct impact of the MC recovery ramp rate on the transient stability of the power system has been addressed by computing the stability margin based on a single machine equivalent method. Furthermore, this paper introduces the critical momentary cessation recovery ramp rate for a specific system, which can be used as an important index in the planning of an IBDG installation. Case studies on modified IEEE 39 bus system and Korean power system were conducted to validate the effectiveness of the proposed method.