| dc.description.abstract | The current distribution systems are typically not designed to accommodate a high level of renewable sources. Customer impact assessment studies are usually required by the distribution utility prior to the connection of DG. In these studies, the impacts of Distributed Generator (DG) on the system voltage profile, reverse power flow, short circuit level, and the system voltage unbalance are evaluated. If the DG failed to fulfill the distribution system technical requirement, the DG project application might be rejected. In some cases, the DG capacity may be reduced to fulfill the technical constraints. In other cases, the renewable based DG power may be curtailed (especially at peak generation). The reduction in DG capacity, as well as the DG active power curtailment, will badly affect the DG project investment.
In order to eliminate the DG active power curtailment, the investor may connect a battery at the same point of the renewable DG. The battery can dispatch the DG generation; therefore, the peak DG power, that causes the violation to the system technical constraints, is shaved. However, the high capital cost of the batteries may negatively affect the investor profit. In such cases, the usage of second life (SL) batteries represents the most useful solution. SL batteries have significantly cheaper capital costs compared to new batteries. Thereby, the major driver for using SL batteries is the possibility of reducing costs and maximizing the DG investment by avoiding the utilization of new Li-ion batteries.
The main aim of this research is to use batteries, which have lost part of their original performance during their first life, with the distribution system applications. The general objective is to utilize the SL batteries for smoothing the photovoltaic based DG power to increase the DG penetration while fulfilling the utility technical constraints. Another objective is to use the SL batteries connected at the same bus of the DG to maximize the DG project investment.
Towards the execution of the proposed research work, some ancillary studies are presented in chapter (3); the results of these studies are used to solve the main problems under study presented in chapter (4). The studies presented in Chapter (3) comprises a probabilistic model for the PV DG, a long-term forecasting technique for the system load, a load flow study to determine the maximum allowable injected DG power, and an economic assessment study to determine the best PV DG capacity that increases the net present value of the profit of the PV DG project.
The results of the aforementioned studies are integrated with the main problems under study that were formulated and solved in Chapter (4). Two main objectives were presented in this chapter; i.e. the first objective is to obtain the optimal size of the SL batteries that achieve zero curtailment while minimizing the battery cost, the second objective is to obtain the optimal schedule of the batteries that maximize the net present value of the profit.
The results obtained show that the SL batteries are adequate for the application, and they have superiority over the brand-new batteries in terms of cost. SLB batteries give a chance to the investor to purchase batteries at low prices at later years of the project rather than purchasing all the required batteries at the beginning of the project. Thus, the SL batteries offer a competitive solution for the cost problems associated with the battery integration with the distribution systems. | en |
