دانلود رایگان مقاله سیستم های حداقل هزینه انرژی خورشیدی برای ایستگاه های پایه ماکرو LTE

Abstract

This paper proposes an algorithm for the identification of the minimum cost solution over a 10 year time horizon to power an LTE (Long-Term Evolution) macro base station, using a photovoltaic solar panel, a set of batteries, and optionally also a secondary power source, which can be a connection to a (possibly unreliable) power grid, or a small Diesel generator. The optimization is formalised as an Mixed Integer Programming (MIP) problem, which, after linearization, can be solved with CPLEX. A heuristic algorithm is also proposed, with the objective of decreasing the computational complexity of the optimization. Numerical results show that a hybrid solar-grid (or solar-diesel) power system saves a significant fraction of the total cost, compared to a pure solar system, and to the traditional power-grid system, over the investigated 10-year period, in a south European city, like Torino in Italy, as well as in a location close to the tropic, like Aswan in Egypt. Our proposed heuristic algorithm can be used to obtain a solution within 10–20% of the optimum, at a computational speed 200 times faster than the MIP solution.

7. Conclusion

In this paper we studied powering systems for LTE macro BSs that make use of solar energy, either relying on renewable energy only, or using a mix of renewable energy and traditional supply. We formulated the problem of the optimal choice of the PV panel size and number of batteries with a Mixed Integer Programming problem of cost minimization. We also proposed a heuristic algorithm which is much more computationally efficient than the MIP problem solution, while being reasonably accurate. To discuss the effectiveness of the investigated BS powering systems, we considered two locations, Torino and Aswan, with quite different solar energy generation patterns. The results show that hybrid systems are much more effective than pure solar energy system. In addition, in the case of Torino, hybrid systems also reduce cost with respect to the traditional power-grid system and to a diesel generator. In Aswan, hybrid systems are economically equivalent to diesel generators, and somewhat more expensive than an existing connection to the power grid, because the electricity and diesel prices are both very low in Aswan. Our study shows that powering BSs with renewable energy sources is today not only possible at reasonable costs, but also in many cases less expensive with respect to more traditional power supply approaches. The forecast technology advances in both solar cells and batteries will make the solar solution even more attractive in the years to come.