Abstract
The stochastic and intermittent nature of renewable energy poses grave challenges to the energy scheduling of micro-grids. The exploitation of batteries has been considered as an effective way to cope with such challenges. However, fluctuation in renewable process causes batteries to charge/discharge frequently, reducing the lifetime and increasing the maintenance cost. This paper presents a hierarchical two-layer energy management, a combination of battery and supercapacitor, to lessen daily energy costs. The upper layer is equipped with a battery to minimize the economic cost, optimizing the energy usage by employing a mixed-integer nonlinear programming (MINLP) model; the lower layer is equipped with a supercapacitor to treat the uncertain nature of renewable energy. The optimization process includes load shifting and battery degradation costs. The upper layer determines the optimal schedule of interruptible appliances and the profile for energy storage for the next 24 hours. The schedule results are then passed to the lower layer, which deals with the forecast uncertainties with a supercapacitor with a 15 minutes interval. The effectiveness of the proposed algorithm is examined by a single-layer scheduling system without forecast errors and a two-layer scheduling system with forecast errors. The obtained results show the capability and effectiveness of the proposed scheduling system to reduce operating costs and forecast errors.
Highlights
T HE sustained growth of energy demand and gas emissions has become a crucial issue of world concern
The investigations on energy scheduling methods have stimulated great interest [1]; uncertainty such as forecasting error is inevitable for energy scheduling, which increases the difficulty of energy control
The battery storage system, which acts as bidirectional mediators to improve energy efficiency with the utility grid, is often integrated into scheduling to deal with uncertainty [2]–[8]
Summary
T HE sustained growth of energy demand and gas emissions has become a crucial issue of world concern. This paper presents a hierarchical two-layer micro-grid energy scheduling framework that combines an optimization layer and a real-time control layer to deal with the differences between an ideal scheme and a real operation. 3) A lower layer strategy is developed to accommodate the imbalanced power mainly due to the uncertainty of the renewable energy and loads, while extending the lifetime of the battery. Compared with other micro-grid energy system publications considering layered and multi-layer, this paper proposes an active error eliminate method to evaluate the impact of uncertainty timely and provides cost-effective real-time optimal measures after occurring uncertainty. It is basically different from the double-layer structure proposed in the literature [12], [13]. The leading purpose of energy scheduling is to control the load for minimizing the financial costs by considering the physical characteristics of appliances
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