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Subject: search.filters.subject.Energy storage

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    Evaluation of grid-scale battery energy storage system as an enabler for large-scale renewable energy integration
    (2022-09-29) Loji, Nomhle; Davidson, Innocent Ewaen; Akindeji, Timothy Kayode
    Because of many substantial benefits over other renewable energy resources (RES), photovoltaic (PV) and wind technologies are the most important emerging renewable energy sources (RES) and they are rapidly and widely propagating. However, they are nondispatchable and, the stochastic and intermittent natures of solar irradiation and wind, are some of the fundamental barriers and challenges to their development and their large-scale deployment. As a result, power systems operators have no control over DG’s available resources and are compelled to operate conventional generators to both cater for normal changes in load demand and make provision for DG’s output variations. These concerns lead to increase the uncertainty in power systems operation as they modify both the structure and the operation of the distribution network by affecting inter alia, the voltage profile and stability, the direction of network power flow and the overall performance of the power system. Enabling PV penetration into electrical grids require a balance of supply and demand that cannot be achieved by oneself. Because of the flexibility to control their real power output, batteries are suggested as a suitable and cost effective solution to mitigate the adverse effects of intermittency and shape the fluctuation of the system’s output into relatively constant power. There is a need to quantitatively investigate and evaluate the performance of the use of BESS that adequately smoothen the output of the PV-BESS sub-system for over-voltage reduction and peak load shaving during the high PV generation – low consumption time in lieu of power curtailment or reactive power injection. Using DigSILENT™ - PowerFactory™ this research work investigated the impacts of BESS on voltage stability and power losses with the aim of increasing system loadability and enhancing stability. A modified standard IEEE 9-Bus was used to perform the studies using four cases and various scenarios and the simulation results and comparative analysis first reveal that the combined effect of the Solar PV-BESS system has a substantial positive impact on the system loadability improvement and reduction of the total power system losses. Results further confirmed the BESS’s ability to act as generator, or load, respectively during high load demand/lower PV generation and lower demand//higher Solar PV generation to contribute to the voltage regulation and power system stability, offsetting effectively the intermittency of Solar PV energy sources and subsequently enabling greater RE penetration.
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    Viability of supercapacitors for energy storage to mitigate renewable energy sources intermittency
    (2019-10) Thakoordeen, Renesh Rajan; Ojo, Evans Eshiemogie
    Energy storage is seen as a solution to assist in the integration of renewable energy by meeting intermittency. Such energy sources suffer from the widely known obstacle of intermittency. To overcome this issue, a formidable energy storage system is required. While large scale energy storage systems such as pumped-storage schemes and compressed air energy storage systems exist, renewable energy sources such as solar and wind power use batteries as a form of energy storage. Additionally, these large scale energy storage systems suffer from a number of drawbacks such as specific location and geophysical requirements. Photovoltaic arrays and wind turbines almost exclusively use batteries as the preferred method of energy storage. Recent years has seen a surge in the advancement of supercapacitor technology. The two main characteristics of supercapacitors are: high power density and low charging time. This has drawn considerable attention to the technology and has thus been implemented in electric buses and hand tools. Other desirable characteristics, as compared to electrochemical batteries, include: smaller weight; lifespan and fewer toxic materials. The last characteristic mentioned is of notable concern since lead-acid batteries are known to emit dangerous gases such as hydrogen and also use sulphuric acid and lead in their production which can lead to laryngeal carcinoma. Latest developments have seen an increase in the overall capacitance (and decrease in cost price) of supercapacitors which may allow supercapacitors to be used as energy storage system, either in a stand-alone or hybrid capacity or both. This study attempts to prove that supercapacitors can replace electrochemical batteries on a domestic scale through simulation where the number of supercapacitors required to supply a domestic load for 24 hours is determined. The time required to charge these supercapacitors is also ascertained. However, it was found that supercapacitor technology is limited to smaller applications or a hybrid design working in conjunction with batteries as protection surge currents.