Improving the islanding detection performance of passive protection by using the undervoltage block function

Abstract

Conventionally, passive techniques are used to protect distributed generators against islanding events. These protections must disconnect the generators as soon as possible, either to de-energize the island or to commute control modes and so that the generators operate isolated as a microgrid. The parametrization of pick-up and time delay of frequency-based and voltage-based protections must be done based on dynamic simulations. Moreover, adjusting the undervoltage block function of frequency-based protection is commonly neglected and either a default value is used, or it is disabled. Thus, this paper proposes a practical methodology to parametrize the undervoltage block function of frequency-based anti-islanding protections. This methodology is a direct method to adjust the undervoltage block and its use resulted in a better performance of the anti-islanding protection. Based on 2149 islanding and 2457 non-islanding events and considering ride-through requirements from IEEE 1547-2018, the voltage block methodology associated with the automatic setting map methodology presented 97.39% of correct islanding detection and 0.16% of incorrect trips.