Integration Of Energy Storage Systems Research Articles

Challenges of existing grid codes and the call for enhanced standards

<abstract> <p>The escalating penetration of renewable energy, notably wind and solar, introduces unique complexities into power systems, particularly in frequency and voltage regulation. Current grid codes are inadequate for these emerging dynamics, necessitating significant enhancements to cope with the evolving energy landscape. The paper highlights several pivotal areas of improvement, including increased flexibility within power systems, integration of energy storage systems, expansion of ancillary services, the inclusion of grid-forming inverters, and the international harmonization of grid codes. The research underscores that conventional power system methodologies, primarily reliant on traditional power plants, fail to manage the fluctuating supply-demand dynamics of renewable energy effectively. By proposing improvements in grid codes, the research contributes towards resolving this issue. Furthermore, the paper underlines the paramount importance of international harmonization of grid codes for system interoperability, efficient operation, and exchange of best practices across diverse regions. Through its exhaustive exploration and recommendations, the study empowers policymakers, grid operators, and energy producers to advance grid code frameworks. Consequently, this facilitates renewable energy integration, ensures grid stability, and paves the way for a more sustainable energy future.</p> </abstract>

Planning method for joint operation of integrated energy storage system considering reliability

A joint operation planning method for integrated energy storage systems considering reliability is proposed. Firstly, the planning of the power exchange level of the energy storage system is achieved by calculating the optimal power exchange level of the supercapacitor, constructing a model for the optimal configuration of the two-layer energy storage, and using an algorithm for the solution of the model to optimise it. In the experiments, the joint operation planning performance of the proposed method is verified. The experimental results show that the model prediction accuracy is high when the proposed method is used for the joint planning of the integrated energy storage system, and has a more satisfactory joint operation planning performance.

Inertia compensation of power grid with flywheel-integrated synchronous condenser

<abstract><p>This paper studies the integration of flywheel energy storage system (FESS) to a synchronous condenser (SC) and its effect on the stability margin of the power system. To show the applicability of FESS-integrated SC in mitigating sudden power loss and sudden load implementation, the experimental and simulation results are presented.</p></abstract>

Environmental and Techno-economic Life Cycle Assessment of Energy Storage Systems in Railway supply system

During rush hours, catenary voltage drop is a significant issue on the 1,5kV – DC lines. Indeed, when voltage drop occures between two substations, the trains can't accelerate as they should. Among the solutions that could solve such a problem, the development of a new traditionnal substation in the middle of two others, also the integration of wayside Energy Storage Systems (ESS). This paper deals with the development on Energy Storage Systems (ESS) in the SNCF (French Railway Company) railway network. It aims to study the techno-economic interests of such innovations, also to investigate the environmental impact they could have. The assessment is based on the comparison of a traditional railway 1,5kV–DC substation and a battery-based substation.

An SOC Based Adaptive Energy Management System for Hybrid Energy Storage System Integration to DC Grid

In this paper, an efficient adaptive energy management strategy (EMS) is presented for a hybrid energy storage system (HESS) application to compensate power fluctuation. The HESS consists of a battery and super-capacitor, which are integrated into the DC grid using a modified triple active bridge converter (m-TAB). The conventional EMS uses a low pass filter (LPF) to distribute high and low-frequency components of power. However, the time constant of the LPF is fixed throughout the process, which discharges the battery at the same rate even near the low state of charge (SOC) region. This increases the degradation rate of the battery. The proposed EMS employs an adaptive time constant LPF-based power allocation method to distribute the total power between the energy storage devices. The adaptive feature of the EMS changes the power distribution ratio dynamically to increase the utilization of the super-capacitor and battery operation time, thereby enhancing the life cycle. The proposed EMS is simulated in MATLAB/SIMULINK platform with the m-TAB converter, and the results are compared with the conventional EMS to prove its superiority. The system is also tested on an experimental prototype of 500 W for different test cases, and the outcomes are presented to support the proposed EMS.

Bidirectional Interleaved DC–DC Converter for Supercapacitor Energy Storage Integration with Reduced Capacitance

This paper analyzes the control method of a multiphase interleaved DC–DC converter for supercapacitor energy storage system integration in a DC bus with reduced input and output filter size. A reduction in filter size is achieved by operating only in modes with duty cycles that correspond to smaller output current ripples. This leads to limited control of the charging and discharging process of the supercapacitor energy storage system. Therefore, a detailed analysis of the optimal charging strategy is provided in this paper for interleaved converters with different numbers of phases. The results show that such control can be used, albeit with some percentage loss in efficiency. Experimental results are presented in this paper to verify the theoretical results.

Review on Recent Strategies for Integrating Energy Storage Systems in Microgrids

Energy security and the resilience of electricity networks have recently gained critical momentum as subjects of research. The challenges of meeting the increasing electrical energy demands and the decarbonisation efforts necessary to mitigate the effects of climate change have highlighted the importance of microgrids for the effective integration of renewable energy sources. Microgrids have been the focus of research for several years; however, there are still many unresolved challenges that need to be addressed. Energy storage systems are essential elements that provide reliability and stability in microgrids with high penetrations of renewable energy sources. This study provides a systematic review of the recent developments in the control and management of energy storage systems for microgrid applications. In the early sections, a summary of the microgrid topologies and architectures found in the recent literature is given. The main contributions and targeted applications by the energy storage systems in the microgrid applications is defined for each scenario. As various types of energy storage systems are currently being integrated for the reliable operation of the microgrids, the paper analyses the properties and limitations of the solutions proposed in the recent literature. The review that was carried out shows that a hybrid energy storage system performs better in terms of microgrid stability and reliability when compared to applications that use a simple battery energy storage system. Therefore, a case study for a DC microgrid with a hybrid energy storage system was modelled in MATLAB/Simulink. The presented results show the advantages of hybrid energy storage systems in DC microgrids.

Expansion planning of joint medium- and low-voltage three-phase distribution networks considering the optimal integration of distributed energy resources

This article proposes a novel hybrid approach based on the three-phase bus impedance matrix to solve the medium and low voltage planning problem of three-phase distribution systems considering the optimal integration of battery energy storage systems (BESSs) and different renewable energy sources (RESs). The mathematical formulation to describe the problem involves a mixed-integer non-linear model that considers the allocation and selection problem of distribution substations and transformers, medium and low voltage branches, RESs, and BESSs. Furthermore, the optimal operation of BESSs, the load balancing among low voltage system phases, the upgrading of existing elements, and the uncertainty of RESs, demands, and energy prices are considered. To solve the investment problem, an Iterated Local Search algorithm with neighborhood structures is applied, which uses the electrical information from the three-phase bus impedance matrix to generate new solutions. In addition, a two-step decomposition stochastic optimal power flow is proposed to solve the operational problem considering the stochastic scenarios. The performance of the new methodology is tested on a real distribution system. The numerical results show that integrating RESs and BESSs in the planning problem minimizes the cost of energy losses by 14.16% and the energy purchased from substations by 18.78%.

Levelling the Photovoltaic Power Profile with the Integrated Energy Storage System

The extensive penetration in the energy mix of variable renewable energy sources, such as wind and solar, guarantees boosting of the transition toward a decarbonized and sustainable energy system as well as tackling of climate targets. However, the instability and unpredictability of such sources predominantly affect their plant production. Thus, utility-scale energy storage is required to aid in balancing supply and demand and, as a result, to prevent unbalances that might cause issues at different grid levels. In the present study, the authors’ patented energy storage technology, known as Integrated Energy Storage System (I-ESS), is combined with a 10 MWp solar plant. The PV plant and the I-ESS unit function as a Virtual Power Plant (VPP). The selected VPP management strategy attempts to optimize the daily hours during which the plant supplies steady power output. Numerical simulations show that the VPP plant can effectively smooth the PV peak and manage the power supply. In particular, by the definition of a novel metric expressing the ratio between regular hours of power provided to the grid plus the energy stored in the backup unit and the total number of hours in a year, the results show that the VPP regularity is relatively high in terms of PV output, ranging from a low of 50% in December to a high of 87% in August. Thus, the proposed VPP arrangement seems to be a promising technology for pushing toward the carbon-neutral transition.

Techno-economic evaluation of combined cycle gas turbine and a diabatic compressed air energy storage integration concept

More and more operational flexibility is required from conventional power plants due to the increasing share of weather-dependent renewable energy sources (RES) generation in the power system. One way to increase power plant's flexibility is integrating it with energy storage. The energy storage facility can be used to minimize ramping or shutdowns and therefore should lower overall generating costs and CO2 emissions.In this article, we examined the effects of a combined cycle gas turbine (CCGT) power plan and a compressed air energy storage (CAES) system integration. The main feature of the CCGT-CAES integration concept is using the CCGT installation as a heat recipient and provider for the CAES installation. This approach was applied to a real-life case study of the PGE Gorzów CCGT power plant. First, technical feasibility of itegrating a CCGT plant with a CAES system was verified and the restrictions on the operating conditions were identified. Next, the improvement in flexibility was quantified by the additional profits gained from the integration. Polish day-ahead electricity prices were used as a measure for remunerating flexibility.Two models were developed in the Python computer programming language: a thermodynamic one and an economic one. The former was buit without the use of flowsheeting software or purpose-built industry specific tool. The latter was implemented within the frame of the PuLP library and solved using its default solver (CBC). By means of mixed integer linear programming (MILP) optimal generation schedules and maximum profits were found for three cases: an independent operation of the CCGT, an integrated CCGT-CAES plant and an integrated CCGT-ES plant with 81% storage efficiency.The results of the computational simulations contradict the supposition that the integration is economically viable, even if mechanical energy storage efficiency of 81% is assumed. Regarding the impact of the integration on the optimal schedule, although it is negligible for the 56% mechanical energy storage efficiency case, a significant change in operation profiles is observed for the 81% case. The model developed here can be used either when making decisions about investment in flexibility improvements or for planning daily operation of a generating unit.

Assessing the Potential Increase in the Energy Storage Density of Subsea Hydro-Pneumatic Accumulators Using Carbon Dioxide in Lieu of Air

Abstract The integration of energy storage systems (ESS) on a large scale is becoming essential to mitigate intermittency issues in power supply from offshore wind farms. This paper deals with an offshore hydro-pneumatic energy storage (HPES) system comprising of a subsea accumulator pre-charged with a compressed gas. The paper applies a simplified thermodynamic model to investigate the potential increase in the energy storage density of the proposed HPES system by replacing air with carbon dioxide (CO2) that is able to undergo a phase change (gas-liquid-gas) during the storage cycle when limiting the peak operating pressure below the critical point. The study is based on a numerical model for simulating the thermodynamics of the entire storage cycle. A sensitivity study is conducted to examine the influence of main operational parameters, primarily the seawater temperature, peak working pressure, and sea depth, on the storage density of the HPES system operating with a dual phase fluid. It is shown that the storage density of HPES accumulators can be increased substantially by using CO2 in lieu of air. The increase in density is found to depend considerably on the seawater temperature and sea depth.

Energy management in Converter-Interfaced Renewable Energy Sources through ultracapacitors for provision of ancillary services

The ever-growing penetration of Converter-Interfaced Renewable Energy Sources (CI-RES) and the gradual decommission of synchronous generators (SGs) are posing several challenges to guarantee the stability and robustness of the electric power system. A possible solution to overcome the foreseen problems is to enable the provision of ancillary services (AS) by advanced CI-RES emulating the SG performance. However, given the fact that most of the CI-RES operate at maximum power point, it will be required to rely on energy storage systems (ESS) to deal with active power related ASs. The ESS integration can be done in a straightforward manner within the CI-RES DC bus by means of a DC/DC converter. It is required, however, an adequate DC energy management to properly control the DC bus voltage, the ESS energy and the power delivered to the grid by the primary power source. This is a major challenge which must be solved to unlock the AS provision by means of CI-RES. With this regard, the main contribution of the paper is the design of an energy management system to simultaneously regulate the CI-RES DC bus voltage using the UC and also maintain the UC voltage within their safety limits while a given AS is provided. The control strategy is validated experimentally using a prototype with results that reveal a reliable and stable operation. • Three-layer hierarchical Energy Management System (EMS) for a Converter Interfaced Renewable Energy Source (CI-RES) comprising an ultracapacitor (UC) for ancillary service (AS) provision. • The DC bus voltage is controlled by the UC being possible to provide accurate AS since the point of interconnection (POI) active power can be precisely defined. • The UC voltage is regulated with a variable gain proportional controller which provides accurate AS while preventing the UC voltage from reaching its technical limits. • The proposed EMS has been tested using a laboratory prototype involving an integrated power electronic stack with a voltage source converter (VSC) and a DC/DC converter, a primary energy source and an UC.

Recent Advancements in Evacuated Tube Solar Water Heaters: A Critical Review of the Integration of Phase Change Materials and Nanofluids with ETCs

Evacuated tube solar water heaters are gaining more attention in the present market scenario as compared to conventional collectors. Such collectors are versatile because no solar tracking is required and the operating temperature range is also broad. Comparatively, it is cost-effective and may attain higher thermal efficiency. However, like other collectors, continuous energy supply is sometimes hampered by the intermittent nature of solar radiation. This problem can be partially resolved by using phase change materials (PCM) in the evacuated tube solar collector (ETC). PCMs can store the energy during the sunshine hours, which can be released when solar energy is not available. In the literature, several studies are available pertaining to the use of PCMs in ETC-based solar water heaters. The literature indicates that the integration of PCMs with ETCs has several merits. Nevertheless, systematic, and comprehensive review papers dedicated to such integrated energy storage systems with ETC solar water heaters are not available. Hence, the objective of this work is to compile the relevant experimental, numerical, and theoretical works reported in the literature. The present paper broadly reviews the recent design modifications, PCM integration with different kinds of ETC water heaters, and their life cycle assessment. Furthermore, studies in the literature pertaining to the application of nanoparticles in ETC systems are also discussed, and finally, a roadmap for this energy storage system is provided.

Impact of Small Scale Storage and Intelligent Scheduling Strategy on Cost Effective and Voltage Secure Operation of Wind+PV+Thermal Hybrid System

AbstractThe growing concern on climate change and environmental pollution has created enormous pressure on shifting the generation toward cleaner and environmental friendly sources. Among different clean energy producers, wind power and solar photovoltaic (PV) systems are the most attractive ones due to their abundant availability, substantial power production capability, and cost effective attributes. But, their intermittent availability makes the system operation extremely vulnerable. Therefore, optimum utilization of renewable energy in hybrid power system (HPS) may not be achievable without the integration of energy storage facilities. In this context, integration of battery energy storage (BES) systems with Wind+PV+Thermal (WPT) hybrid configuration is considered in this work to meet the sudden and short term disharmony between actual and available renewable power output. Moreover, to maintain a secure system voltage of the WPT+BES system, the impact of reactive power (Q) capability of doubly fed induction generator has also been analyzed. The scheduling problem of the proposed HPS is solved by formulating in an optimization framework. Intelligent technique is applied to evaluate the optimal operational paradigm at multiple percentage of renewable energy penetration scenarios at which the proposed HPS may operate in a voltage secure and cost effective manner. The validation of the proposed operating strategy on the comparative performance evaluation of WPT and WPT+BES systems is portrayed on IEEE30 bus benchmark power system configuration.

Thermally integrated energy storage system for hybrid fuel cell electric bike: An experimental study

The hybrid fuel cell/battery technology is an attractive option for a sustainable mobility with zero emissions. In fact, this solution owns system scalability features and high efficiency and, compared to battery electric solutions, it offers advantages in terms of flexibility of use and fast charging times. However, the thermal management for the battery in this type of powertrain is a crucial issue, since operating temperatures can significantly affect safety and performance. In this study, an innovative system aimed at providing high storage energy density and improving the battery pack performance of hybrid fuel cell/battery vehicles is investigated for use on-board of a plug-in fuel cell electric bike. The proposed system, developed by the authors in previous studies, integrates the battery pack with a hydrogen storage based on metal hydrides. The idea behind this solution is to exploit the endothermic desorption processes of hydrogen in metal hydrides to cool down the battery pack during operation. An experimental analysis is conducted to assess the thermal management capabilities of this system: by considering a typical duty cycle designed on the base of road test measurements, battery pack temperature profiles are evaluated and compared against those from a control experiment where no battery thermal management is enabled (i.e. no hydrogen desorption from the metal hydride tank). The results show that, beside enhancing the on-board stored energy capacity, the proposed system represents an effective solution to provide an efficient thermal management for the battery pack, with significant advantages in terms of attainable riding range.

Optimizing Fuel Efficiency on an Islanded Microgrid under Varying Loads

Past studies of microgrids have been based on measurements of fuel consumption by generators under static loads. There is little information on the fuel efficiency of generators under time-varying loads. To help analyze the impact of time-varying loads on optimal generator operation and fuel consumption, we formulate a mixed-integer linear optimization model to plan generator and energy storage system (ESS) operation to satisfy known demands. Our model includes fuel consumption penalty terms on time-varying loads. We exercise the model on various scenarios and compare the resulting optimal fuel consumption and generator operation profiles. Our results show that the change in fuel efficiency between scenarios with the integration of ESS is minimal regardless of the imposed penalty placed on the generator. However, without the assistance of the ESS, the fuel consumption increases dramatically with the penalty imposed on the generator. The integration of an ESS improves fuel consumption because the ESS allows the generator to minimize power output fluctuation. While the presence of a penalty term has a clear impact on generator operation and fuel consumption, the exact type and weight of the penalty appears insignificant; this may provide useful insight for future studies in developing a real-time controller.

Progress in research and development of phase change materials for thermal energy storage in concentrated solar power

Concentrated solar power (CSP) technologies are seen to be one of the most promising ways to generate electric power in coming decades. However, due to unstable and intermittent nature of solar energy availability, one of the key factors that determine the development of CSP technology is the integration of efficient and cost-effective thermal energy storage (TES) systems. Sensible heat TES system is the most widespread technology in commercial CSP plants, however, due to the requirement of high specific heat of the storage material, large size and bigger temperature difference between the heat transfer fluid and the storage material, sensible energy storage systems suffer from a low energy density and temperature degradation during discharging. In this context, over the past ten years, interest in phase change materials (PCM) has resurfaced considerably, mainly motivated for the deployment of latent heat TES system for CSP application that utilizes PCM. Though there have been some review studies on the application of PCM in CSP plants, however these are either over 5 years old or give a general overview of PCM application in CSP plants. To bridge this gap, this work presents a comprehensive review on the actual state of all major components of cutting-edge PCM based TES technologies for CSP application and condenses all the available information and categorizes them considering the main functional parts and remarking the current research progress in each part as well as the future challenging issues. It intends to understand and explain the foundations of the innovative concepts, future research directions and strategies developed over the past 10 years to tune the engineering and thermal sciences of PCM based TES systems. Insight into classes of PCM TES storage materials with details like their geometrical configurations, design parameters, physical properties, operational issues, cost, technology readiness level, suitability to CSP application and comparative assessment of various PCM based TES systems is provided.

Chance-constrained model predictive control-based operation management of more-electric aircraft using energy storage systems under uncertainty

On more electric aircraft (MEA), reducing fuel consumption and guaranteeing flight safety are pursued by efficient operational management of the electrical power system (EPS). Considering the growing number of onboard electric loads and the increasing complexity of EPS architecture due to the integration of multiple power converters and energy storage systems (ESSs), system-level operation control is required to manage power distribution, load scheduling, and ESSs. In this paper, a chance-constrained stochastic model predictive control (CC-SMPC) method is proposed to improve both the system operation in terms of the system's cost and reconfiguration activities as well as the ability to cope with uncertainties due to fluctuating load demands. Both normal and faulty operating conditions are investigated with multi-failure cases, resulting in different uncertainty propagation paths. The system's operational and technical requirements are formulated as a set of deterministic and probabilistic constraints in the CC-SMPC model. To verify the effectiveness of the proposed strategy, a comprehensive comparison study is conducted. Two uncertainty/failure cases are taken into account and simulations are performed for both offline and online control strategies while the Monte-Carlo algorithm is used for scenario generation. The results are evaluated using the proposed evaluation framework, showing that the CC-SMPC achieves better performance compared to deterministic MPC (DMPC) in both cases. In an offline testing framework, comparing the performance of DMPC and CC-SMPC strategies shows that CC-SMPC reduces the power constraint violations for batteries and generators in all cases following the selected confidence level. In addition, in an online testing framework with 1 % violation probability, the following results are observed in the two cases: In the EPS normal condition, CC-SMPC reduces the total cost by 31.4 % and the overall constraint violation cost by 93 %; while in the EPS faulty condition, CC-SMPC reduces the total cost by 4.37 %, and the overall constraint violation cost by 96 %.

Technical and economic evaluation, comparison and optimization of a Carnot battery with two different layouts

Integrating energy storage systems into electricity distribution systems can improve flexibility, stability and reliability. This issue becomes even more important in renewable resources-assisted energy production systems; because such systems are less reliable due to the intermittent nature of renewable resources. Carnot battery energy storage is a relatively new and emerging approach that is able to solve many challenges of available storage technologies (cost and geographical dependencies). In this regard, in the present article a Carnot battery based on pumped thermal energy storage system (PTESS), organic Rankine cycle (ORC) and vapor heat pump (VHP) has been assessment and discussed in two different modes from the perspectives of thermodynamics, exergy, costing and optimization. In the first case, both charge and discharge modes have a waste heat recovery process (using a regenerator). However, in the latter case, both mentioned modes do not have a waste heat recovery process. Therefore, the purpose of the current article is to examine and compare two different modes of a Carnot battery. Additionally, the minimum value of Levelized cost of storage (LCOS) (as an objective problem) is determined based on the artificial bee colony algorithm. The outcomes revealed that at 120 °C, the LCOS and net investing cost values for the considered storage configuration were almost 0.293 USD/kWh and 5450 thousand USD. Furthermore, a comparison of the considered storage configuration with the no-regenerators mode confirmed that the embedding of regenerators in both the charge and discharge sub-cycles could reduce the LCOS value by nearly 10 %.

Optimal economic dispatch of hybrid microgrids integrating Energy Storage Systems with Grid-Forming Converters

New control strategies based on Grid-Forming converters make possible the operation of isolated microgrids without the support of synchronous generation. This paper proposes an Energy Management System algorithm that optimizes the operation of a microgrid, maximizing the integration of renewable energy and considering the possibility of disconnecting all synchronous generators. The algorithm is applied to a microgrid modelled with real data and two economic dispatch strategies are analysed: the first requires keeping at least one synchronous generator connected to provide frequency regulation following standard practice; and the second considers the disconnection of all conventional generation relying on the capabilities of Grid-Forming converters when sufficient reserve is available. The results show that the proposed strategy reduces the operational cost of the system, as well as solar PV curtailment and diesel consumption.