Search results for "Three phase"

The rheology of three-phase suspensions at low bubble capillary number

2015

We develop a model for the rheology of a three-phase suspension of bubbles and particles in a Newtonian liquid undergoing steady flow. We adopt an 'effective-medium' approach in which the bubbly liquid is treated as a continuous medium which suspends the particles. The resulting three-phase model combines separate two-phase models for bubble suspension rheology and particle suspension rheology, which are taken from the literature. The model is validated against new experimental data for three-phase suspensions of bubbles and spherical particles, collected in the low bubble capillary number regime. Good agreement is found across the experimental range of particle volume fraction ([Formula: s…

A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units

2013

In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have an important role in optimal management of such systems.

Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids

2014

This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes the problem of OPF in islanded microgrids showing loads unbalance.

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…

Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units

2015

In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating the contextual adjustment of the droop parameters used for primary voltage and frequency regulation of inverter interfaced units. The work proposes a mathematical method for the OPF solution also considering the droop parameters as variables. The output of the OPF provides an iso-frequential operating point for all the generation units and a set of droop parameters for primary regulation. In this way, …

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 …

Spin-valve current sensor for industrial applications

2003

This work presents an industrial application of a new spin-valve current sensor based on the giant magnetoresistance effect (GMR) and provides a comparison between this sensor and the typical sensor used in these applications, the hall sensor. Experimental results derived from the application of this two sensors in a power application (a bi-directional three-phase rectifier) are shown.

Gas-liquid-solid operation of a Long Draft Tube Self-ingesting Reactor (LDTSR)

2008

Gas-liquid stirred vessels are widely employed to carry out chemical reactions involving a gas reagent and a liquid phase. The usual way for introducing the gas stream into the liquid phase is through suitable distributors placed below the impeller. An interesting alternative is that of using “self ingesting” vessels where the headspace gas phase is injected and dispersed into the vessel through suitable surface vortices. In this work the performance of a Long Draft Tube Self-ingesting Reactor dealing with gas-liquid-solid systems, is investigated. Preliminary experimental results on the effectiveness of this contactor for particle suspension and gas-liquid mass transfer performance in pres…

Mass transfer and hydrodynamic characteristics of a Long Draft Tube Self-ingesting Reactor (LDTSR) for gas-liquid-solid operations

2011

Gas-liquid stirred vessels are widely employed to carry out chemical reactions involving a gas reagent and a liquid phase. The usual way for introducing the gas stream into the liquid phase is through suitable distributors placed below the impeller. An interesting alternative is that of using “self ingesting” vessels where the headspace gas phase is injected and dispersed into the vessel through suitable surface vortices. In this work the performance of a Long Draft Tube Self-ingesting Reactor dealing with gas-liquid-solid systems, is investigated. Preliminary experimental results on the effectiveness of this contactor for particle suspension and gas-liquid mass transfer performance in pres…