Optimal Power Allocation for Energy Harvesting and Grid Power Hybrid Systems

The power allocation problem in a hybrid system with power grid and energy harvesting is investigated to maximize system throughput. From the power grid, peak power constraints and the total energy budget constraint are considered. Water-Filling has been used as a fundamental algorithm to solve the target problem. We proposed the optimal power allocation solution by first applying water-filling to the available grid power, followed by applying water-filling recursively to allocate the harvest energy.% Our research shows that these two water-filling steps are not commutative for optimal solution. The steps of the proposed algorithm are precisely defined. The proposed algorithm provides the exact optimal solution via efficient finite computation. The optimality is strictly proved. Numerical examples are provided to illustrate the algorithm steps via finite computation to obtain the optimal exact solution. The results obtained by applying the proposed algorithm are compared with the primal-dual interior point method (PD-IPM). Significant enhanced throughput can be achieved. Algorithm complexity is analyzed. Therefore, even if the most promising algorithm of PD-IPM is implemented, the performance of our proposed algorithm still shows much better.