Search results for "Power flow"

Power tracking with maximum efficiency for wireless charging of E-bikes

2014

Wireless charging techniques, based on Inductive Power Transfer (IPT), are attractive for Electric Vehicles (EV), due to benefits such as convenience and safety. An accurate valuation of the maximum achievable efficiency in an IPT system is extremely unlikely due to the high sensitivity to parasitic elements variations. Therefore, an “on site” procedure of power efficiency characterization is useful to get a precise description of the efficiency curve and obtain the actual maximum efficiency. In this paper, a power tracking algorithm aiming at efficiency maximization is proposed for a Wireless Charging system. The algorithm aims at finding the maximum power transfer efficiency with respect …

Current transformers effects on the measurement of harmonic active power in LV and MV networks

2011

The harmonic active power is used to determine the location of polluting loads, the direction of harmonic power flow and to estimate how consequential a certain current harmonic source is. The highest uncertainties, when measuring harmonic active power, are introduced by the current and voltage transducers. This paper presents experimental results which show the impact of current transformers (CTs) on the accuracy of the harmonic power measurements. An expression for the evaluation of the power error in distorted conditions was developed which can be easily utilized in the case of linear current transducers. It is shown how CTs cannot be considered linear transducers and how the higher the …

Optimizing droop coefficients for minimum cost operation of islanded micro-grids

2017

This paper shows how minimum cost energy management can be carried out for islanded micro-grids considering an expanded state that also includes the system's frequency. Each of the configurations outputted by the energy management system at each hour are indeed technically sound and coherent from the point of view of generation-consumption balancing by exploiting a frequency dependent load flow algorithm. A Glow-worm Swarm Optimization (GSO) algorithm carried out in a 24 hour time frame provides optimized results. A test has been carried out for a residential PV-Storage-Microturbine islanded micro-grid to show the feasibility as well as the efficiency of the proposed approach and results ar…

Ancillary Services in the Energy Blockchain for Microgrids

2019

The energy blockchain is a distributed Internet protocol for energy transactions between nodes of a power system. Recent applications of the energy blockchain in microgrids only consider the energy transactions between peers without considering the technical issues that can arise, especially when the system is islanded. One contribution of the paper is, thus, to depict a comprehensive framework of the technical and economic management of microgrids in the blockchain era, considering, for the first time, the provision of ancillary services and, in particular, of the voltage regulation service. When more PV nodes are operating in the grid, large reactive power flows may appear in the branches…

Frequency constrained optimal Power Flow based on Glow-worm Swarm Optimization in Islanded Microgrids

2015

This work presents an application of a swarm optimization method to solve the optimal power flow problem taking into account the constraints of frequency and line ampacity in three-phase islanded Microgrids. Each generation unit is equipped with a Power Electronics Interface. In the considered formulation, the droop control parameters are considered as variables to be adjusted by a higher control level, while the frequency is kept in rated bounds. Another typical constraint for OPF formulation, the max ampacity of each line, is also considered. Two case studies with different dimensions and electrical features have been considered and the obtained results show the efficiency of the proposed…

A model for reactive power tracing by addition of fictitious nodal injections

2012

Abstract This paper proposes an efficient solution to the problem of reactive power flow tracing in electrical transmission networks. For such systems, the tracing techniques used for active power flows cannot be used straightforwardly, due to reactive power variations induced by the line reactances, these variations often being comparable to the powers delivered to the loads. In other words, as is well known, in transmission systems the reactive flows are strongly influenced by the inductive and capacitive effects of the network, making the tracing of power flow and allocation of losses more critical. In this paper, after discussing some methodological aspects, an approach based on the use…

ANALISI DI SCENARI RELATIVI ALLA MESSA IN SERVIZIO DEL NUOVO COLLEGAMENTO A 380KV SORGENTE-RIZZICONI (II) E DI ALTRE INTERCONNESSIONI AT NELL’AREA DE…

La sempre maggior produzione di energia elettrica da FRNP in Sicilia, ed i nuovi sviluppi da qui a qualche anno sulla rete elettrica siciliana, stimolano ad effettuare degli studi su come il sistema elettrico dell’isola possa evolversi nei prossimi anni. Anche i nuovi collegamenti e le nuove interconnessioni, attualmente solo in fase di scheduling/progettazione, che si apprestano ad essere realizzati nell’area mediterranea, incoraggiano ad effettuare delle analisi su come il sistema elettrico isolano possa farsi trovare pronto a supportare le grosse iniezioni di potenza che in futuro investiranno la regione. Questo lavoro di tesi dopo aver analizzato lo stato della rete AT siciliana, sia ne…

Optimal Operating Point Calculation for Medium Voltage Distribution Systems

2007

The paper deals with the calculation of the optimal working point of a distribution system, equipped with several distributed generators, able to operate also autonomously, i.e. disconnected from the main grid. When connected to the main grid, it appears in general convenient to assign the slack bus role to the bus that represents such a connection. The problem becomes more complex when maximum power transfer constraints through the connection must be taken into account. The adequate slack bus treatment is even more important when the optimal operating condition must refer to the condition subsequent to an intentional or unintentional disconnection from the main grid. The paper presents an …

Real-Time Minimization Power Losses by Driven Primary Regulation in Islanded Microgrids

2020

Islanded microgrids are small networks that work independently from the main grid. The frequency and voltage in islanded microgrids are affected directly by the output power of distributed generators and power demand variations. In this work, a real-time driven primary regulation, which relies on optimized P-f droop coefficients, is proposed. In all operating conditions, it minimizes the power losses for islanded microgrids. The proposed configuration will allow the optimization modules to interact with each other and adjust parameters producing a suitable power sharing among generators. The methodology is tested based on a hardware-in-the-loop experimental set-up where distributed generato…

Distributed optimal power flow for islanded microgrids: An application to the Smart Polygeneration Microgrid of the Genoa University

2016

In this work, the application of an original distributed optimal power flow method to test a microgrid in the Savona area, Italy is proposed. The microgrid shows different types of Distributed Energy Resources (DERs) and is connected to the main grid through a fixed power bus. Due to the high computational speed, the applied distributed Optimal Power Flow can be performed almost in real time, i.e. every 5 minutes or less. The operating solution found for generators, simply using local information, corresponds to a suboptimal condition with reduced losses, bus voltages and line currents within constrained intervals. The distributed optimization algorithm is iterative, but also fast. It is ba…