Search results for "Power Flow"
showing 10 items of 30 documents
OPTIMAL POWER FLOW IN ISLANDED MICROGRIDS
In this thesis, studies about OPF in islanded MGs have been carried out. First, an original formulation and solution approach for the OPF problem in islanded distribution systems is proposed. The methodology is well suited for AC microgrids and can be envisioned as a new hierarchical control structure comprising only two levels: primary and tertiary regulation, the latter also providing iso-frequency operating points for all units and optimized droop parameters for primary regulation. The OPF provides a minimum losses operating point for which voltage drops are limited and power sharing is carried out according to the most adequate physical properties of the infrastructure thus giving rise …
A decoupled method for solving distribution networks with PV nodes
2009
In this paper, a methodology for the load flow solution of distribution systems with fixed voltage nodes (PV nodes) is presented. The proposed technique is the extension of a methodology already set up by the authors to solve distribution systems; it is an iterative approach devoted to the treatment of voltage dependent loads; at each iteration, all the network components (lines, loads, and PV nodes) are represented by resistances and reactances. The methodology is based on the identification of two networks that are solved in sequence, thus allowing the attainment of state features of the original system. One of the two systems is made up only of shunt and series resistances; the other onl…
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 …
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…
REGULATION DROOP COEFFICIENTS IN ISLANDED MICROGRIDS
In this thesis, a novel non-linear droop control is proposed. The droop curve is generated as a piecewise linear curve from the optimized operating points of the system under consideration for different values of the supplied load. For each Optimal Power Flow (OPF), the droop coefficients are generated and these create small piecewise linear parts of the final droop curve. The operation is constrained by frequency and voltage limits. It is well known that the load flow problem solution can provide infinite operating points if the generators set point is not fixed. For each loading condition, the solution to the OPF problem outputs a single solution. Such solution, in case of microgrids with…
Wireless Charging Systems for Electric Vehicle Batteries
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…
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…
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 …