Capacity overprovisioning in mobile networks leads to underutilization of network resources and thus inefficient operation from a power consumption perspective. In addition, as operators constantly evolve their networks to denser heterogeneous layouts, with overlaying macrocellular base stations coexisting with numerous smaller cells, to cope with upcoming increase in peak mobile data traffic, the energy consumption of mobile networks will continue to grow in the next years. In this context, although backhaul connections can be responsible for tremendous power consumption, the corresponding study is usually neglected in most of the recent energy related literature. An approach for fast and low cost connectivity of dense microcellular sites is the deployment of wireless in-band backhaul links via existing macrocellular base stations. In this paper, we consider this wireless in-band backhaul approach, where access and backhaul links share the same frequency spectrum, and examine joint energy efficient resource optimization on both links. We introduce an iterative low-complexity polynomial backhaul-aware heuristic, which directs traffic to the most energy efficient network resources, and compare it against i) an exhaustive search method that provides optimum results, ii) a previously proposed reference algorithm, and iii) ordinary Full Operational Topology (FOT) network, where no energy aware technique is applied. From the results obtained, we conclude that our heuristic achieves high energy efficiency gains in all scenarios examined, while wireless in-band backhaul method proved a solid choice for this purpose.

Keywords: Energy efficiency, green communications, LTE, wireless in-band backhaul, heterogeneous mobile topology.

This paper analyses the modelling and control of the grid connected wind energy conversion system (WECS). The required power for grid connected load is effectively supplied by the proposed wind turbine, permanent magnet. And at the grid connected voltage source inverter utilizes a simple FLC with hysteresis current controller (HCC), which suits well for variable speed operation of a wind turbine with direct driven PMSG. Detailed modelling and controller strategies of overall system performance during the transient and dynamic conditions of the proposed system are analyzed to show the effectiveness of the controller strategies. The simulations have been done using MATLAB/Simulink.

Keywords: Permanent magnet synchronous generator (PMSG), State of charge (SOC), Fuzzy logic controller (FLC), Hysteresis current controller (HCC), Boost converter, Voltage source inverter (VSI), Smart grid.

The depleting nature of fossil fuels and the environmental threats have resulted in the emergence of renewable energy sources (RESs) as alternative and accessible energy resources. Amongst various RESs, wind energy is one of the fastest growing distributed energy resources because of its zero-carbon emission and cost efficient generation. Although wind energy is plentiful, it is of intermittent nature, i.e., the wind speed is not constant throughout. So, the strategy followed is to harness maximum output power from this variable wind as when it is available, and various algorithms for maximum power operating point tracking (MPPT) have been proposed and implemented successfully. However, choosing an exact MPPT algorithm for a particular application requires a high degree of skill as each algorithm has its pros and cons. This paper presents a review of various MPPT algorithms suggested in the literature.

Keywords: WECS, MPPT, TSR, P&O, ORB.

Energy is the most important factor for the economic development of a country. In order to cope with increased demand of energy, an efficient photovoltaic (PV) power generation system needs to be developed. The efficiency of PV module is very less and it shows nonlinear characteristics due to variation in solar irradiance and operating temperature. The efficiency of the PV system can be improved by operating the system at its maximum power point (MPP) which can be accomplished by adopting maximum power point tracking (MPPT) techniques. This paper addresses implementation of an fuzzy logic based MPPTmethod. MPPTtracking mechanism such as Perturb and Observe (P&O) MPPT algorithm and Fuzzy-MPPT (FMPPT) for PV power generation system are implemented in this work. The performance ofFMPPTis compared with that of P&O MPPT. Since FMPPT can handle nonlinearity very well and can track the MPP more precisely and rapidly, it provides better performance than P&O technique in tracking of MPP.

Keywords: Photovoltaic, MPP, Perturb and Observe, Fuzzy-MPPT.