Reliability Evaluation of Active Distribution Networks Including Islanding Dynamics

This paper presents a model that incorporates the impact of islanding dynamics in reliability evaluation of active distribution networks. In order to do that, the effects of the islanding process in terms of voltage and frequency variations, as well as the impact of component failures, are taken into consideration in the reliability assessment. The proposed model is based on a combination of probabilistic reliability evaluation with the dynamic simulation of the islanding process. The reliability evaluation is performed by Non-Sequential Monte Carlo simulation, while the islanding process is evaluated by a transient stability simulation with complete models of synchronous machine and its voltage and speed regulators. Results are obtained for a MV distribution test system, where the influence of dynamics in the survivability rate of islanding is incorporated into the calculation of traditional reliability indices, leading to more realistic results.

I. Introduction

Distributed Generation (DG) units, in the distribution network, can cause positive and negative impacts, especially when associated with sources of intermittent nature. The concept of Active Distribution Networks (ADN) has been introduced to maximize the benefits of DG. ADN are defined as self-managing distribution systems, where small and mid-sized generators are integrated into the distribution control centers, in order to provide an efficient, safe and reliable way to enable the operation of the so-called microgrids [1]. Microgrids, in turn, can be characterized as distribution networks containing distributed generators that can operate interconnected to the distribution network or, in cases of emergency, isolated, fed by their own resources.