Protection and stability assessment in future distribution networks using PMUs

Phasor Measurement Units (PMUs) have the potential to play an essential role in power system monitoring and operation in the future, particularly for power systems incorporating increasing amounts of distributed generation (DG) and possibly systems operating in islanded mode in the future [1]. Their ability to directly measure and provide the voltage and current phasors at the PMU location offers numerous possibilities for ascertaining information relating to the state and health of the power system. Typical applications of PMUs in distribution networks include: state estimation, dynamic stability supervision, instability prediction and control, protection and fault location, and power quality monitoring [2]. This paper presents a brief overview of the applications of PMU-enabled distribution network functions, with a focus on loss of mains (LOM) protection using a model that is representative of a distribution network incorporating DG. The paper reports on extensive simulations that have been carried out in order to develop a PMU-based system that can detect (very quickly) loss-of mains conditions under situations where local (i.e. potentially islanded) load and DG output is very closely balanced. Furthermore, it is demonstrated that the developed PMU-based LOM system can identify and differentiate between load transients, local short circuits and true loss of mains conditions under a variety of different scenarios. Future activities in the project are also presented.