Effect of Islanding and Telecontrolled Switches on Distribution System Reliability Considering Load and Green-Energy Fluctuations

Abstract

Abstract:To improve electrical distribution network reliability, some portions of the network could operate in autonomous mode, provided that the related technical issues are addressed. More specifically, when there is not a path from those portions to the primary substation due to a fault in the network, such portions could be disconnected from the main network and supplied by local generation only. Such a mode of operation is known as "intentional islanding" and its effectiveness, in terms of adequacy, depends on the ability of the local generation to meet the island's load. In fact, the ratio between the available local generation and load demand can frequently change during islanding due to load variations and, especially, due to the strongly irregular behavior of the primary energy sources of renewable generators. This paper proposes an analytical formulation to assess local generation adequacy during intentional islanding, accounting for the aforementioned variations. More specifically, the fluctuations of load and green-energy generators during islanding are modeled by means of Markov chains, whose output quantities are encompassed in the proposed analytical formulation. Such a formulation is used by the analytical equations of load points' outage rate and duration. The evaluation of the reliability indices accounts for a protection scheme based on an appropriate communication infrastructure. Therefore, a brief overview on the telecommunications technologies has been presented with reference to their suitability for the specific application. In particular, distribution network safety issues have been considered as the main concern. The results show that neglecting load and generation fluctuations leads to a strong overestimation of the ability of distributed generators to meet the island load. Through a case study it is observed that the error on the load point outage rate is greater than the one affecting the outage duration.

An Analysis of the Energy Storage for Improving the Reliability of Distribution Networks

“…A first criterion results in no load being restored if there is a generation shortage at any moment of the adequacy evaluation period. A second criterion is to restore the supply in those time intervals that have sufficient generation to supply the load and guarantee the non-occurrence of repetitive interruptions in restored customers [32,33]. An alternative option for increasing the load restoration is the application of load-shedding actions under conditions of limited generation in the island [26,28,34] (more details in Section 2.4.4).…”

Reliability-Based and Cost-Oriented Product Optimization Integrating Fuzzy Reasoning Petri Nets, Interval Expert Evaluation and Cultural-Based DMOPSO Using Crowding Distance Sorting

“…Culture-based DMOPSO was carried out with the Matlab software. The related operating parameters are determined as internal swarm size popnum = 100, external swarm size paretomax = 100, iteration number maxgen = 200, global optimum step size cg = 2(cg is within [1,3]), inertia weight winertia = 0.4, mutation probability pmutate = 0.1 and float mutation index mum = 20. The redundant particles are excluded according to the crowding distance sorting.…”

“…Thus, it is imperative to improve the product reliability optimization design [1]. It is an important analytical tool to enhance the inherent reliability of products, and the reasonable and effective reliability optimization design has a guiding significance for the later product detailed design [2,3]. At the same time, the product cost is also a determining factor which can decide their market competitiveness, and, during application in practical engineering, the product optimal design scheme with high reliability and minimum cost is often desired by designers and customers [4,5].…”

Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System

“…Accordingly, the demand for the use of renewable energy sources, such as wind power, solar energy, and biomass, has rapidly increased [1][2][3]. To meet the demand and reduce the problems associated with the depletion of fossil fuels and environmental pollution, numerous studies have been conducted for green energy and renewable energy development [4][5][6]. The common renewable energy systems are wind power generation (WPG), which uses wind turbines, and solar energy generation (SEG), which uses photovoltaic cells.…”