Search results for "microgrids"

A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part I: Underground Station and Car Parking

2021

This paper reports the results of a simulation study with the aim of evaluating the capability of two portions of a hybrid AC/DC MV/LV network of maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, the study aims to verify, in the case of islanded operation of the two microgrids, the continuity of the electricity service by exploiting the local generation plants, Energy Storage Systems (ESSs), and other flexible resources managed by suitable algorithms in different energy scenarios. The analysis was carried out considering two microgrids: an underground station and a car parking with Electric Vehicles (EVs). For assessing the per…

Short-circuit Calculations in Hybrid AC/DC Microgrids

2022

In this paper, the issues related to short-circuit calculations in hybrid AC/DC microgrids are discussed. The reference standard for short-current calculations in DC systems is the IEC 61660, which provides a mathematical formulation of the problem. The standard only includes radial DC grids and does not consider a more complex system, such as meshed DC systems or a hybrid AC/DC microgrid. This paper proposes a generalized approach that can be used independently of the characteristics of the hybrid system. The proposed approach is applied to two test microgrids and the results are compared with those obtained simulating the same grids with Neplan 360.

Dynamic Control of Static Converters for the Transition from Grid-on to Grid-off Operation of AC/DC Microgrids

2022

In this paper, specific control logics defined for generators, controllable loads and electric energy storage systems are illustrated in order to improve the reliability of AC/DC hybrid microgrids in their grid-off operation following failure events such as short-circuits, line breaks, sudden disconnections of generating units or loads, etc. After defining specific control schemes, these were modelled in a digital environment and finally tested with dynamic simulations. Finally, the paper highlights the role of virtual synchronous machine control for the self-healing capacity of islanded hybrid microgrids.

Assessing the Economic Benefit due to BESS Management in a Renewable Energy Community of a Small Island

2022

The paper presents a study carried out on the island of Pantelleria regarding the interaction among distributed energy resource and energy storage systems in renewable energy communities. EU, in the Clean Energy Package, defines the 'Jointly acting renewables self-consumers' (JARSCs) and the 'Renewable Energy Communities' (RECs) as innovative models to share energy from renewables facilities. Nevertheless, the behaviour of JARSCs and RECs is designed to maximize the final users' self-consumption without considering the impacts on the power grid operation. A comparison of various operational strategies of BESS and an investigation of their effect on the distribution network are key elements …

Frequency Dynamics in Fully Non-Synchronous Electrical Grids: A Case Study of an Existing Island

2022

The operation of a power system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the design and the control of the system. Existing literature on the integration of renewable energy sources in isolated systems mainly focuses on energy aspects or steady-state issues, and only a few studies examine the dynamic issues of autonomous networks operated with fully non-synchronous generation. A lack of research can be found in particular in the determination of the required amount of grid-forming power, the selection of the number and rated power of the units which should implement the grid-forming controls, and the relative locations of …

A New Meta-Heuristic Multi-Objective Approach For Optimal Dispatch of Dispersed and Renewable Generating Units in Power Distribution Systems

2011

The application of stochastic methods in engineering research and optimization has been increasing over the past few decades. Ant Colony Optimization, in particular, has been attracting growing attention as a promising approach both in discrete and continuous domains. The present work proposes a multi-objective Ant Colony Optimization for continuous domains showing good convergence properties and uniform coverage of the non-dominated front. These properties have been proved both with mathematical test functions and with a complex real world problem. Besides the second part of the chapter presents the application of the new algorithm to the problem of optimal dispatch of dispersed power gene…

INVERTER-BASED DISTRIBUTED GENERATORS, MODELING AND CONTROL

In the last few years, electrical power generation is moving from a centralized generation towards distributed generation including on-site Renewable Energy Sources (RESs). In order to overcome RES related issues, as intermittent and fluctuating power, storage elements are included in the on-site generation system. The interaction between distributed generator (DG) units including RES, storage and front-end power converters should be carefully modeled in order to analyze the power system stability. An accurate modeling of DGs is required. In this thesis, a new modeling approach has been proposed for the inverter-based DGs based on the concept of electrostatic synchronous machines. Detailed …

Multi-objective long term optimal dispatch of distributed energy resources in micro-grids

2010

The amount of distributed generators in power distribution systems is evermore increasing, and the potential benefits and drawbacks are becoming clearer. The optimal management of Distributed Energy Resources (DER) in microgrids is essential to guarantee their best exploitation. Optimal operation allows to maximize their benefits, such as reduction of network energy losses, reduction of carbon emissions and to minimize the negative effects of a strong DER penetration, such as the increase of infrastructural investment and operational costs. Hence, DER management is a multi-objective problem in which many objectives of interest, often conflicting, need to be optimized simultaneously. In this…

Demand Response Pricing Strategies for Islanded Microgrids

2013

In this paper, Time of Use and Critical Peak Pricing policies are designed and their effects on optimized operation is evaluated. For this purpose, an optimal operation algorithm is employed and the relevant production costs are derived. As far as the Time of Use policy is concerned, such costs are observed to be different in two time intervals of the day, due to the loads changing effect and the production of renewable energy. Whereas in the Critical Peak Pricing Policy, a peak time interval is identified to set up different pricing rates. The optimization algorithm used to carry out the work described above minimizes the microgrid's energy losses, the production costs and the Green House …

Demand Response Service Certification and Customer Baseline Evaluation Using Blockchain Technology

2020

The use of Distributed Ledger Technologies such as Blockchain for certifying Demand Response services allows for the creation of a distributed system in which customers can communicate with the system operator to provide their flexibility, in a secure, transparent and traceable way. Blockchain technology also supports incentive mechanisms for users taking part in the service through the generation of utility tokens to recognize the user's contribution. This paper presents the experimental test of a novel methodology for Demand Response programs implementation by using the Blockchain technology. The latter is employed for defining a distributed Demand Response service and a new system for it…