Search results for "d-a"
showing 10 items of 426 documents
Techno-economic optimum sizing of hybrid renewable energy system
2013
Using off grid hybrid renewable energy systems for rural electrification has become an attractive solution for those areas, where grid electricity is not feasible or cost of the grid extension is relatively large. Hybrid system combines several energy systems together, therefore it can supply high reliable electricity rather than a PV/battery system or a wind/battery system. But the most important thing is that the system should be economically attractive. To achieve both of these features, each of the components in the hybrid system should be optimally sized. This requires a detailed techno-economic analysis of different possible hybrid system configurations. The objective of this study is…
Comparison of power quality impact of different photovoltaic inverters- the viewpoint of the grid
2005
This paper presents the results of an experimental analysis performed with the aim of evaluating the effect of many photovoltaic plants on power quality of the grid. Several parameters as voltage and current distortion, flicker, voltage variations at fundamental frequency and power factor have been observed. The measured values have been compared with the limits reported in the standards and, when possibiIe, their dependence on the characteristics of the grid in terms of its impedance has been pointed out.
Techno-economic sizing of off-grid hybrid renewable energy system for rural electrification in Sri Lanka
2015
Abstract Off-grid hybrid renewable-energy-based power systems for rural electrification have become an attractive solution for areas where grid electricity is not feasible. Hybrid energy systems use several energy technologies, and the selection of proper technologies with optimum sizing of the selected components has become very important. The objective of this study has been to investigate the optimum configuration of a hybrid system that can supply electricity to a rural community in Sri Lanka. A rural village in Siyambalanduwa (Sri Lanka) comprising approximately 150 households with a resultant daily electricity demand of 270 kWh and a nighttime peak of 25 kW has been studied. This regi…
Sensorless small wind turbine with a sliding-mode observer for water heating applications
2015
Water heating applications consume a considerable portion of electricity demand in most of countries. Small wind turbines are one of attractive alternatives for grid electricity based water heating systems. Wind energy can be converted to heat energy in a high efficient manner. However it is essential that wind turbine based water heating systems should be economical and reliable. Maximum power point tracking algorithm of most of available wind turbines requires information from a wind speed sensor and a rotor speed sensor which reduces the reliability of the system. In this paper, the proposed 5 kW wind turbine does not require external wind speed sensors and rotor speed sensors. The syste…
GA-ANN for Short-Term Wind Energy Prediction
2011
Wind turbine power output is totally intermittent in the nature. For grid connected wind turbine generators, power system operators (transmission system operators) need reliable and robust wind power forecasting system. Rapid changes in the wind generation relative to the load require proper energy management system to maintain the power system stability and of course to balance the power generation, frequency, voltage regulation within the statutory limits. Accurate wind energy forecasting helps the power system transmission system operators in anticipating rapid changes in wind turbine power output with respect to load and helps in making decision not only for optimum energy management bu…
Real time assessment of hand-arm vibration system based on capacitive MEMS accelerometers
2012
Vibrations are a well known potential cause of health diseases and therefore constitute a main concern for the safety of workers in a large number of activities. In order to prevent health hazards, national and international institutions have issued laws and directives which establish recommended limits to the workers' exposure to vibrations during operations. Consequently, if the amount of adsorbed vibration exceeds the allowable daily limits the worker has to stop his job. Recent wireless sensing and communicating technologies can effectively be employed for such purpose, allowing to develop monitoring customized devices at affordable cost which could be easily employed during the workers…
Multi-objective strategies for management and design of distributed electric storage systems in a Mediterranean island
2013
The paper proposes an analytical study about the design and operation of distributed Electrical Storage Systems(ESS) in an active distribution network supplying a Mediterranean island, according to different criteria. The approach is based on the application of a multi-objective optimization algorithm (NSGA-II) that outputs a set of optimized schedules of the ESS in different configurations when operated according to different criteria (minimum energy losses in the grid, total generation cost, greenhouse gas emissions, limiting the fluctuations of the generation from fossil fuel plants). Moreover the variability of the voltage profile has been investigated also by a comparison with a refere…
Numerical Analysis of Medium Scale PV Plants and Their Power-Flow Control System With a Simple Three Phase Inverter
2012
This paper presents a mathematical analysis of a medium scale Photovoltaic (PV) power generation system connected to the distribution network and of its control system, in which the conversion stage is unique thanks to the absence of a boost chopper. Boost choppers are usually used as actuator for maximum power point tracking (MPPT). The conducted analysis leads to the conclusion that the used inverter presents two degrees of freedom that can be easily exploited in a control system in which the inverter simultaneously realizes the interconnection to the grid and at the same time realizes the MPPT control. The structure of the control system is then presented, discussed and then validated by…
A New Device for the Control and the Connection to the Grid of Combined RES-based Generators and Electric Storage Systems
2013
In this paper a new device for the control and the connection to the supply utility grid of combined RES-based generators and electric storage systems is presented. The device is a bidirectional converter that can be controlled so as to facilitate the interface between the low voltage grid and photovoltaic or wind generators combined with batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. In the paper the functioning of the device and its circuit diagram are described, the single parts are shown and the potentiality of its control system are commented. © 2013 IEEE.
A novel fuel cell-based power system modeling approach
2013
Nowadays, fuel cells are the most promising source of energy for stationary applications. Unfortunately, the power density of fuel cells is not adequate for modern applications. A fuel cell - based hybrid power supply is required. The fuel cell is coupled with a high-energy density power source to improve performances of the composite power source. A power management stage is introduced between the two basic sources to control the power flow path from the fuel cell to the auxiliary source and the load. In order to avoid effects of a limited power density of the fuel cell on the whole power supply, sophisticated power management algorithms are implemented. Accurate modeling is required to te…