S. Thai Subha

Control of power converter for power quality improvement in a Grid Connected PV system

RENEWABLE energy sources are spreading due to environmental and energetic shortcomings. These systems are usually grid connected, and a power converter is the key item to connect the renewable energy sources to the grid. The power converter must be accurately designed in order to comply with grid requirements in terms of power quality and safety. This paper focuses on the design, modeling and control of power converters for power quality improvement in a grid connected Distributed Generators system. In this paper Photovoltaic is considered as DG. Control action of power converters are designed such that they can figure out with a transformer coupled grid connected system with different voltage levels of the grid. The Grid Connected Photovoltaic system in which a low voltage based PV generation system fed to grid of 25 kV and 125 kV along with the effect of irradiance on active power fed to grid is demonstrated All the simulations are carried out in MATLAB/Simulink environment and the results with priggish analysis are exhibited.

Ergodic capacity analysis and asymptotic tightness for multi-element antenna array with spatial correlation and transmit water-filling

The authors analyse ergodic capacity for a system employing multi-element antenna array at the transmitter and receiver side. The signal is assumed to have both line-of-sight and non-line-of-sight (NLOS) components characterised by Rician fading distribution. The presence of the cluster of scatterers which gives rise to NLOS components is modelled using Von Mises Fisher (VMF) distribution. The impact of spatial correlation on capacity is graphically presented using MATLAB. The effect of channel state information at the transmitter side is analysed and plotted. Uniform circular array (UCA), which has been proved to outperform uniform linear array, is used at both the transmitter and the receiver. Furthermore, the effect of the radiation pattern of a UCA on the received signal-to-noise ratio is also plotted. Closed-form expressions for asymptotic tightness and upper bound of the system incorporating VMF distribution are obtained and plotted.

Spectrum efficiency for Rayleigh fading channels with Selection combining in the prsescence Co-channel Interference

In this paper, closed form expressions for capacities per unit bandwidth for Selection Combining (SC), when subjected to Co-channel Interference (CCI), are derived for Optimal power and rate adaptation, Optimal rate adaptation with constant transmit power, Channel inversion with fixed rate, Truncated channel inversion with fixed rate policies. Optimal power and rate adaptation policy provides the largest spectrum efficiency and Channel inversion with fixed rate policy provides the largest spectrum efficiency penalty over other adaptation policies for the diversity scheme discussed. SC diversity with Optimal power and rate adaptation policy yields highest spectrum efficiency when subjected to CCI.

System performance of Rayleigh fading channel in the presence of adjacent channel interference

In this paper, the authors study the system performance of adaptive transmission techniques in the presence of adjacent channel interference (ACI). The authors obtain closed-form expressions for system capacity when employing different adaptive transmission policies with and without diversity schemes. The simulation results of spectrum efficiency in a WiMAX network employing 256 orthogonal frequency division multiplexing subcarriers are obtained for the analytical expressions derived for selection combining diversity under various adaptation policies. Analytical results show that the optimal power and rate adaptation policy provides the highest spectrum efficiency. Both analytical and simulation results are found to be in close agreement with each other, which shows that the obtained analytical results works well with the scenario of ACI. Also, maximal ratio combining scheme yields the highest spectrum efficiency when subjected to ACI.

Performance Analysis of Rayleigh Fading Channel in the Presence of Co-channel Interference with Multiple Interferers Under Different Adaptation Policies

In this paper, an approach to performance analysis on signal-to-interference ratio operating over Rayleigh fading channels experiencing an arbitrary number of multiple, Rayleigh co-channel interferers is presented. We have presented a general analysis of selection combining, where each branch experiences an arbitrary number of multiple equal power co-channel interference. Useful closed-form expressions are derived for the probability density function and cumulative distribution function at the output of the combiner. Also, outage analysis is performed in order to show the effects of interferers and diversity order. Capacity per unit bandwidth expressions are derived for selection diversity scheme under different adaptation policies.

Spectrum Efficiency of WiMAX Networks in the Presence of Interference with Diversity Combining

Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data services upto the requirements at the customers end. The objectives of this paper is to evaluate the Performance evaluation of a WiMAX system under various diversity schemes (Selection combining, Maximal ratio combining and Equal gain combining), employing different adaptive transmission policies, such as Optimal power and rate adaptation policy, Optimal rate adaptation with constant transmit power policy, Channel inversion with fixed rate policy, and Truncated channel inversion policy, subjected to co-channel interference and adjacent channel interference. WiMAX system incorporates OFDM with 256 sub-carriers with QPSK modulation as the transmission scheme. Simulated results of the estimated spectrum efficiency show that the implementation of Optimal power and rate adaptation policy under Selection combining is highly effective to combat co- channel interference and adjacent channel interference in the WiMAX communication system. Keywords-channel interference; Adjacent channel interference; Optimal power and rate adaptation policy; Optimal rate adaptation with constant transmit power policy; Channel inversion with fixed rate policy; Truncated channel inversion with fixed rate policy.

Spectrum efficiency and outage probability of fixed WiMAX networks in the presence of co-channel interference with diversity combining

The objectives of this paper is to evaluate the performance of a WiMAX system under various diversity schemes (Selection combining, Maximal ratio combining and Equal gain combining), employing different adaptive transmission policies, such as Optimal power and rate adaptation policy, Optimal rate adaptation with constant transmit power policy, and Channel inversion with fixed rate policy, subjected to co-channel interference. The WiMAX system incorporates OFDM with BPSK modulation as the transmission scheme. Simulated results of the estimated spectrum efficiency shows that the implementation of Optimal power and rate adaptation policy is highly effective to combat co-channel interference in the WiMAX communication system, under Selection combining.

Implementation of lean E-AIR concepts for mass production motor assembly line

In mass production manufacturing industries, Lean manufacturing principles were used to improve the process efficiency by eliminating non value adding activities. In the conventional practice of lean manufacturing, only the practices of inventory control, JIT single piece flow, kanban tools are used. This paper is concerned with the implementation of lean principles as well as new methodology E-AIR (Eliminate, automate, integrate, re-engineering). Areas of improvement in the assembly lines are very high in mass production motor manufacturing industries; The Lean manufacturing will give the result of higher productivity, high degree of global (international) product quality with competitive cost benefit. In this paper, the Lean principles were applied to window lift motor assembly line and engine cooling fan motor assembly in order to manufacture the motors with optimum cycle time, increased productivity, higher degree of quality to meet international automotive standard and to exceed the customer expectations and needs.