iosr-JEEE   Volume-6 ~ Issue-4

Abstract: Natural gas compressibility factor (Z) is key factor in gas industry for natural gas production and transportation. This research presents a new natural gas compressibility factor correlation for Niger Delta gas fields. First, gas properties databank was developed from twenty-two (22) laboratory Gas PVT Reports from Niger Delta gas fields. Secondly, the existing natural gas compressibility factor correlations were evaluated against the developed database (comprising 22 gas reservoirs and 223 data sets). The developed new correlation was used to compute the z-factors for the four natural gas reservoir system of dry gas, solution gas, rich CO2 gas and rich condensate gas reservoirs, and the results were compared with some exiting correlations. The performances of the developed correction indicated better statistical ranking, good graph trends and best crossplots parity line when compared with correlations evaluated. From the results the new developed correlation has the least standard error and absolute error of (stdEr) of 1.461% and 1.669% for dry gas; 6.661% and 1.674% for solution; 7.758% and 6.660% for rich CO2 and 7.668% and 6.661 % for rich condensate gas reservoirs. The new correlation also show high correlation coefficient of: 93.39%, for dry gas; 89.24% for solution gas; 83.56% for rich CO2 and 83.34% for rich Condensate gas reservoirs. Also the proposed new model maintained good graphical trends for four z-factors matched it: experimental, estimated (Standing – Katz) and the best evaluated correlation when matched. Very good crossplots parity line performance when compared with the evaluated correlations. It could then be concluded that the new developed correlation and that of Papay correlation are most appropriate correlations for calculating natural compressibility for Niger Delta gas fields. Carr, Kobayashi, and Burrows (1954) and Wichert–Aziz (1972), correction factor methods; were applied to correct the presence of non-hydrocarbons. But the major setbacks on laboratory analyses for PVT behavior are sometimes expensive and time consuming. Correlations, which are used to predict gas compressibility factor, are much easier and faster than equations of state, invariably save cost.

Key words: Niger Delta Gas, developing Compressibility factor, Evaluation, Correlations.

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Abstract: In present world usage of fossil fuels are increasing, in order to decreasethem the alternate option isRenewable-energy-basedmicrogrids, they are a better wayof utilizing renewable power and reduce the usage of fossil fuels.Usage of energy storage becomesmandatory when such microgridsare used to supply quality power to the loads. Microgrids have twomodes of operation, namely, grid-connected and islanding modes.During islanding mode, the main responsibility of the storage isto perform energy balance. During gridconnected mode, the goalis to prevent transmission of the renewable source intermittency and load fluctuations to the grid. Energy storage of a single typecannot perform all these jobs efficiently in a renewable poweredmicrogrid. The alternating nature of renewable energy sourceslike photovoltaic (PV) demands usage of storage with high energydensity. At the same time, quick fluctuation of load demandsstorage with high power density. This paper shows a compositeenergy storage system (CESS) that contains both high energy densitystorage battery and high power density storage ultracapacitorto meet the aforesaid requirements. By using DAB powerconverter configuration and the energy management scheme canactively distribute the power demand among the different energystorages.Using fuzzy logic controller

Keywords: Bidirectional converter, energy management,energy storage, interleaved modulation, modular design andmicro grid

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Abstract: In this paper MATLAB based steady-state analysis of self excited induction generator is presented and different test models are given to calculate the all parameters which are required in 3-ɸ cage induction motor working as a generator in the self-excited mode of operation. It is well known that, harmonics are generated at the input side of the induction generator due to the presence of nonlinear circuits (rectifier circuit). In this paper, the various nonlinear loads (rectifier loads) connected with the SEIG are simulated and evaluated. The fast Fourier transform (FFT) algorithm is used to analyze the harmonic voltages and currents under steady-state conditions. Simulation is carried out for the proposed system using MATLAB/Simulink software power system tools.

Index Terms- SEIG, Total harmonics distortion, Harmonics Factor, FFT.

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