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This paper presents a cloud energy storage (CES) architecture for reducing energy costs for residential microgrid users. The former of this article concentrates on identifying an appropriate battery technology from various battery technologies with the aid of a simulation study. The later part addresses the economic feasibility of the storage architecture with three different scenarios namely grid connected energy storage, distributed energy storage (DES) and CES. The performance of the proposed architecture has been evaluated by considering five residential users with suitable battery technology identified from the former part of the study. For the purpose of the analysis, PV and load profiles including seasonal effects and grid price were taken from IIT Mumbai, India and IEX portal, respectively. In addition, this article also examines the impact of increased number of users with CES. The value of this study is that the proposed CES architecture is capable of reducing the cost of electricity experienced by the user by 11.37% as compared to DES. With this, CES operator’s revenue can be increased by 6.70% in summer and 16.97% in winter in the case of fixed number of users. Finally, based on the analysis and simulation results, this paper recommends CES with Li-ion battery technology for residential application.

Energy storage is essential for balancing the generation and load in power systems. Building a battery energy storage system (BESS) with retired battery packs from electric vehicles (EVs) or plug-in hybrid electric vehicles (PHEVs) is one possible way to subsidize the price of EV/PHEV batteries, and at the same time mitigating forecast error introduced by load and renewable energy sources in power systems. This paper proposes a detailed framework to evaluate end-of-life (EOL) EV/PHEV batteries in BESS application. The framework consists of three parts. A generalized model for battery degradation is first introduced. It is followed by modeling the battery retirement process in its first life. Two vehicle types—EV and PHEV—as well as two retirement modes—nominal and realistic modes—are considered. Finally, the application of the second-life BESS in power systems is modeled in a detailed economic dispatch (ED) problem. This is how second-life BESS’s performance translates into cost savings on power generation. An optimization problem is formulated to maximize total cost savings in power generation over the battery’s second life. This is done by striking a balance between short-term benefit (daily cost savings) and long-term benefit (cost savings through service years). Numerical results validate the effectiveness of the proposed framework/models. They show that battery usage and retirement criterion in its first life directly affect the performance in its second life application. In our case study, EV battery packs possess larger EOL energy capacities and consequently generate more cost savings in the second life. However, the BESS built from retired PHEV batteries has higher cost savings per MWh. It is because, with the proposed degradation model, battery health is better preserved in PHEV applications. Compared to nominal retirement mode, realistic retirement mode results in extra cost savings due to the reduced first-life service years.

This paper presents a literature review on current practices and trends on cyberphysical security of grid-connected battery energy storage systems (BESSs). Energy storage is critical to the operation of Smart Grids powered by intermittent renewable energy resources. To achieve this goal, utility-scale and consumer-scale BESS will have to be fully integrated into power systems operations, providing ancillary services and performing functions to improve grid reliability, balance power and demand, among others. This vision of the future power grid will only become a reality if BESS are able to operate in a coordinated way with other grid entities, thus requiring significant communication capabilities. The pervasive networking infrastructure necessary to fully leverage the potential of storage increases the attack surface for cyberthreats, and the unique characteristics of battery systems pose challenges for cyberphysical security. This paper discusses a number of such threats, their associated attack vectors, detection methods, protective measures, research gaps in the literature and future research trends.

Seeking 100% renewable energy source (RES) penetration in low-inertia, isolated grids presents major challenges, including frequency control and stability. This is the case in small island systems relying on variable RES and pumped-hydro storage, where the limited ramping capabilities of hydro turbines compromise their frequency response. In this study, solutions are examined to allow the operation of such systems under 100% RES conditions. The Greek island of Ikaria is used as a study case, supplied by a hybrid RES-storage facility, consisting of hydroelectric units, a pumping facility and a wind farm. Solutions under study include the implementation of deflector control to allow provision of fast reserves by the Pelton hydro turbines, primary reserves provision by the wind farm, the enhancement of the variable speed pump control to contribute to primary frequency regulation, and, at a further step, the installation of battery energy storage to provide fast response for effective frequency regulation. All solutions are comparatively assessed via simulation to demonstrate that the proposed deflector control allows effective frequency regulation, albeit at the detriment of energy efficiency, whereas the variable speed pumps may also contribute to primary regulation in case of contingencies. It is battery storage that would decisively enhance frequency control and security of operation, while also allowing for improved tracking of wind power variations in normal operation; best results are achieved when batteries are combined with the other supplementary regulation measures, allowing a reduced battery capacity.

Flexibility has become a requirement for modern power systems dominated by renewable generation sources. It can be extracted from different assets, ranging from demand response to fast generating units. This paper proposes an investment model that finds an optimal mix of transmission-level non-generation flexible assets: battery energy storage (BES), thyristor-controlled series compensators (TCSC), and transmission lines. The role of BES is to offset renewable generation in time, but its power converter is additionally utilized to provide voltage regulation by injecting/withdrawing reactive power. TCSC is used to alter power flows and increase existing lines' capacity, while new power lines are used to increase bulk power transfer. The proposed planning model uses a linearized AC OPF and employs Benders' decomposition to develop an iterative procedure for obtaining the optimal solution. The presented case study illustrates usefulness of the model for different BES costs and investment policies.

With the increasing application of battery energy storage in buildings, networks and transportation, an emerging challenge to overall system resilience is in understanding the constituent asset health. Current battery energy storage considerations focus on adhering to the technical specification of the service in the short term, rather than the long-term consequences to battery health. However, accurately determining battery health generally requires invasive measurements or computationally expensive physics-based models which do not scale up to a fleet of assets cost-effectively. This paper alternatively proposes capturing cumulative maloperation through a physics model-free proxy for cell health, articulated via the strong influence misuse has on the internal chemical state. A Hidden Markov Chain approach is used to automatically recognize violations of chemistry specific usage preferences from sequences of observed charging actions. The resulting methodology is demonstrated on distribution network level electrical demand and generation data, accurately predicting maloperation under a number of battery technology scenarios.

The number of used batteries is increasing in quantity as time passes by, and this amount is to expand drastically, as electric vehicles are getting increasingly popular. Proper disposal of the spent batteries has always been a concern, but it has also been discovered that these batteries often retain enough energy perfectly suited for other uses, which can extend the batteries' operational lifetime into a second one. Such use of batteries has been termed as the “second-life,” and it is high time to adopt such usage in large scale to properly exploit the energy and economics that went into battery production and reduce the environmental impacts of battery waste ending up in landfills. This paper aids in that quest by providing a complete picture of the current state of the second-life battery (SLB) technology by reviewing all the prominent work done in this field previously. The second-life background, manufacturing process of energy storage systems using the SLBs, applications, and impacts of this technology, required business strategies and policies, and current barriers of this technology along with potential solutions are discussed in detail in this paper to act as a major stepping stone for future research in this ever-expanding field.

The renewable-plus-storage power plant is becoming economically viable for power producers given the maturing technology and continued cost reduction. However, as batteries and power conversion systems remain costly, the power plant profitability depends on the capacity determination of the battery energy storage system (BESS). This study explored an approach for optimal capacity determination of a BESS combined with renewable energy considering the complex degradation of lithium-ion batteries. The proposed sizing algorithm iteratively evaluates the effect of BESS operation on battery degradation and estimates the cash flows of the power plant. In addition, we studied battery augmentation that adds the storage capacity in the base system to sustain the BESS capacity throughout the project planning horizon. Using data from South Korea, we showed that both the optimal storage capacity and project profitability are higher when the BESS is combined with solar generation than when combined with wind generation. Moreover, simulation results demonstrated that the proposed battery augmentation scheme improves the project profitability by deferring the upfront cost of batteries and increasing the total revenue. The proposed approach can provide a comprehensive framework for the parties involved in a BESS project to accurately calculate the BESS sizes and maximize the project profitability.