Deployment Of Energy Storage Systems Research Articles

Analysis of the evolution path of new energy system under polymorphic uncertainty—A case study of China

The exploration and promotion of new energy constitute a significant initiative for numerous countries in their pursuit of sustainable development and efforts to alleviate climate change. However, the influence of a multitude of uncertain factors on the evolutionary path of new energy is currently poorly studied. By establishing a dynamic evolution model for new energy under polymorphic uncertainty, this paper analyses the complex interaction between new energy, economic growth, and carbon trading over the period 2020–2060, using China as a case study. We employ numerical simulation and sensitivity analysis to investigate the evolutionary trajectories of the new energy system under various parameter value scenarios. We show that the evolutionary trajectories will undergo substantial fluctuations before 2030, subsequently stabilizing from 2030 onwards. The study highlights that an excessively rapid pace of new energy development is detrimental to new energy systems, whereas energy storage system deployment has the opposite effect. There exists a significant risk of the system collapsing as a result of slow new energy development, over-building energy storage facilities, or over-intervening in carbon trading. We also find that overdevelopment of energy storage system may have greater negative impacts on the economic system than underdevelopment.

Environmental impact analysis of lithium iron phosphate batteries for energy storage in China

The deployment of energy storage systems can play a role in peak and frequency regulation, solve the issue of limited flexibility in cleaner power systems in China, and ensure the stability and safety of the power grid. This paper presents a comprehensive environmental impact analysis of a lithium iron phosphate (LFP) battery system for the storage and delivery of 1 kW-hour of electricity. Quantities of copper, graphite, aluminum, lithium iron phosphate, and electricity consumption are set as uncertainty and sensitivity parameters with a variation of [90%, 110%]. The results show that global warming potential is 9.08E+01 kg CO2 eq. and fossil resource use is 1.21E+03 MJ, with uncertainty ranges of [8.54E+01, 9.23E+01] and [1.15E+03, 1.23E+03], respectively. Electricity consumption during the manufacture and installation process is the greatest contributor to climate change (CO2 eq. emissions), accounting for 39.71% and largely owing to non-renewable sources, followed by cathode materials at 27.85% and anode materials at 18.36%. The disposal and recycling process offers emission reductions but requires an additional 1.17% use of fossil resources. Sobol T indices for the quantity of electricity are the highest for acidification, climate change, fossil resource use, and ionizing radiation. By considering the pathway of China’s electricity mix from 2020 to 2050 under the Paris Agreement’s 2° target, the potential for environmental emission reduction in the system is evaluated. The results show that the greener electricity mix could lead to a 24.59% reduction in acidification impact, a 35.74% reduction in climate change impact, a 33.24% reduction in fossil resource use, and a 44.13% reduction in ionizing radiation impact. This study offers a comprehensive view of the environmental impact reductions associated with the lithium iron phosphate battery and its industry.

Battery Electric Storage Systems: Advances, Challenges, and Market Trends

The increasing integration of renewable energy sources (RESs) and the growing demand for sustainable power solutions have necessitated the widespread deployment of energy storage systems. Among these systems, battery energy storage systems (BESSs) have emerged as a promising technology due to their flexibility, scalability, and cost-effectiveness. This paper aims to provide a comprehensive review of the diffusion and deployment of BESSs across various applications, analyzing their impact on grid stability, renewable energy integration, and the overall energy transition. The paper examines the key drivers and challenges associated with BESS adoption, as well as market trends influencing their proliferation. Through an analysis of empirical data, this study aims to shed light on the current state of BESS diffusion. Finally, this research contributes to the knowledge base surrounding battery storage technology and provides insights into its role in achieving a sustainable and reliable energy future.

Navigating the Cost-Efficiency Frontier: Exploring the viability of Grid-Connected energy storage systems in meeting district load demand

In this investigation, we explored the cost-effectiveness and operational efficiency of grid-connected Energy Storage System (ESS) technologies—specifically, Proton Exchange Membrane-Reversible Fuel Cell (PEM-RFC) and Li-ion Battery (LIB)—with the goal of meeting load demand. Our conclusion reveals that integrating ESS isn't the optimal solution due to impractical implementation costs, making reliance solely on grid electricity a more pragmatic choice. Despite this, a secondary optimum value emerged, suggesting economic viability for ESS integration and introducing a dynamic trade-off between cost considerations and energy storage utilization. Furthermore, our study conducted a sensitivity analysis, anchored in the target costs set by the US Department of Energy, to identify conditions under which ESS systems could transition from impractical to feasible. The results outlined the potential to reduce the levelized cost of energy (LCOE) but also emphasized the prospect of increasing the storage factor by optimizing various system characteristics. Crucial factors like capital cost, efficiency, and lifetime were identified as pivotal in shaping the economic landscape of ESS integration. The study showcased tangible outcomes upon sensitivity analysis, including a 12% reduction in PEM-RFC LCOE and 58.5% reduction in LCOE for LIB, indicating improved cost efficiency and feasibility of ESS integration to the grid. To address a critical research gap, this study provides a novel comparison between PEM-RFC and LIB technologies as ESS, considering dynamic grid electricity prices. It sheds light on intricate dynamics that must be considered in ESS deployment decisions, emphasizing the delicate balance between cost-effectiveness and operational efficiency. Focused on the electricity load demand of commercial buildings in the Santa Barbara district, our techno-economic assessment contributes valuable insights for informed decision-making in ESS integration.

Applications of energy storage systems in power grids with and without renewable energy integration — A comprehensive review

Energy storage system (ESS) is recognized as a fundamental technology for the power system to store electrical energy in several states and convert back the stored energy into electricity when required. Some excellent characteristics such as availability, versatility, flexible performance, fleet response time, modularity etc., make ESS more attractive for power system applications. The ESS has signification contributions and applications to operate the power system optimally in power grids with and without integrating renewable energy (RE) systems. This paper presents a comprehensive review of ESS technologies and their applications in power grids. Five different types of ESS, namely mechanical, chemical, electrical, electro-chemical and thermal, are elaborately explored with their key characteristics and applications. A summary of comparative analysis to find the appropriate ESS for power system applications and an analysis of the practical implementation of different ESS worldwide have been presented briefly, reflecting the suitability of ESS for power system applications. The comparative analysis further demonstrates the nature of various ESS, including their advantages and limitations in specific applications. The major challenges from these analyses are identified to be the capacity of ESS, RE integration, high maintenance and implementation cost of ESS, ESS degradation, waste management and associated environmental pollution. Moreover, the review finds out that there are still numerous challenges in terms of technology and economy that need to be addressed to make the practical applications of ESS viable for power industries. The reviews also identify recent key researches that can effectively address those issues and explore the future directions researchers can undertake to improve various characteristics of ESS. Finally, the transition pathway to promote ESS for power systems applications with and without integration of RE systems is discussed to demonstrate the possibility and potentiality of large-scale ESS deployment for a sustainable climate-friendly future.

Energy storage systems for commercial buildings in dense urban regions: NYC case study

In response to the mounting interest in Battery Energy Storage Systems (BESS) from a wide range of entities—commercial, private, and governmental—this paper analyzes the decision-making criteria for BESS implementation. The structure of electricity bills are analyzed to understand the current cost structure of building utility tariffs. In addition, the potential revenue streams provided by various incentive programs, including demand response contracts, when implementing BESS were investigated. Highlighting the need for a pragmatic and efficient ranking system, we propose a model that leverages load profile data to determine the suitability of BESS implementation within a portfolio of buildings. This approach offers property owners a streamlined method to prioritize which buildings to equip with BESS. To validate the efficacy of our load profile-based model, we compare it against established financial models, specifically employing the System Advisory Model (SAM) from the National Renewable Energy Lab (NREL). Our findings indicate that a load profile-centric ranking system can effectively determine the most appropriate buildings for ESS implementation. This paper provides a substantial contribution to the field of BESS sizing, offering a simplified yet robust methodology for ranking that aligns well with more complex financial models. By focusing on the practical utility of load profile data, we enable a simplified and informed process for property managers to make sound decisions in the deployment of energy storage systems.

Operation optimisation of integrated energy systems based on cooperative game with hydrogen energy storage systems

The presence of distributed energy sources in integrated energy systems make it difficult to meet the real-time balance between supply and demand, requiring the deployment of energy storage systems. Hydrogen storage can compensate for the lack of electrochemical energy storage in the energy, time and space dimensions. Meanwhile, the cooperative operation of participants within an integrated energy system, compared to individual operation, can help generate additional benefits and reduce carbon emissions. Therefore, this paper proposes a method for optimising the operation of integrated energy systems based on a cooperative game containing hydrogen energy storage systems. Firstly, a model for optimising the operation of an integrated energy system with hydrogen storage energy system considering the revenue from hydrogen sales is constructed. Secondly, a benefit allocation mechanism for the cooperative game based on the shapley value method is proposed. Finally, the BPSO-SA optimisation algorithm is proposed for solution. The total operating cost of the collaborative operation scenario is reduced by 22.96% and the carbon emissions are reduced by 80.11% compared to the independent operation scenario, the operating cost savings and carbon emissions reduction are allocated to the participants according to their contribution, encourage participants to build integrated energy systems through collaboration.

Lessons learned from large‐scale lithium‐ion battery energy storage systems incidents: A mini review

AbstractThe deployment of energy storage systems, especially lithium‐ion batteries, has been growing significantly during the past decades. However, among this wide utilization, there have been some failures and incidents with consequences ranging from the battery or the whole system being out of service, to the damage of the whole facility and surroundings, and even personnel injury and casualties. Some of these events have documentations on the event details and findings. This mini review paper contributes to the existing literature related to lithium‐ion batteries thermal incidents by presenting and discussing the documented findings of these most recent incidents. In some cases, the lithium‐ion battery system has complied to the most recent standards related to battery systems such as UL 9540 and UL 9540A thermal runaway propagation test; yet fire incident and propagation nonetheless occurred. Hence, the lessons learned from these documentations are valuable for the next development of the battery system and technology. Some key lessons from selected cases will be discussed, including specific lithium‐ion battery system risks and their countermeasures, while covering several related standards, and identifying possible gaps in the existing standards.

A Two-stage Stochastic Mixed-integer Programming Model for Resilience Enhancement of Active Distribution Networks

Most existing distribution networks are difficult to withstand the impact of meteorological disasters. With the development of active distribution networks (ADNs), more and more upgrading and updating resources are applied to enhance the resilience of ADNs. A two-stage stochastic mixed-integer programming (SMIP) model is proposed in this paper to minimize the upgrading and operation cost of ADNs by considering random scenarios referring to different operation scenarios of ADNs caused by disastrous weather events. In the first stage, the planning decision is formulated according to the measures of hardening existing distribution lines, upgrading automatic switches, and deploying energy storage resources. The second stage is to evaluate the operation cost of ADNs by considering the cost of load shedding due to disastrous weather and optimal deployment of energy storage systems (ESSs) under normal weather condition. A novel modeling method is proposed to address the uncertainty of the operation state of distribution lines according to the canonical representation of logical constraints. The progressive hedging algorithm (PHA) is adopted to solve the SMIP model. The IEEE 33-node test system is employed to verify the feasibility and effectiveness of the proposed method. The results show that the proposed model can enhance the resilience of the ADN while ensuring economy.

A Low-Pass Virtual Filter for Output Power Smoothing of Wind Energy Conversion Systems

As theincrease of wind power penetration, the fluctuations of wind power results in serious power system frequency turbulences. This article proposes a low-pass virtual filter (VF) for wind energy conversion systems (WECSs) to smoothen output power. First, a linearized model is established for a WECS. Then, a low-pass VF is derived for the active power control loop in WECS to modulate the kinetic energy stored in rotating mass for output smoothing. The principle is to modify the traditional wind power controller to emulate a physical energy storage system controlled as a low-pass filter to smooth the wind power output. The proposed low-pass VF does not need the physical deployment of energy storage system but still can filter the high-frequency fluctuations in the output wind power. Furthermore, in order to ensure operation stability of the wind turbine (WT), a stability-constrained coefficient is determined according to the proposed stability criteria to ensure the stability of WTs. Simulation and experiment results verify the effectiveness of the proposed VF in WECS for output wind power fluctuation reduction and the stability-constrained coefficient for stability ensuring.

Planning the deployment of energy storage systems to integrate high shares of renewables: The Spain case study

The intermittent nature of the renewable energy sources with the greater potential, wind and solar, requires dealing with temporary mismatches between demand and supply. The object of this study is to assess the Spanish energy plan from a system perspective regarding the energy storage requirements to meet electricity demand with high penetrations of renewable energy generation. We use a model that builds on existing literature and commercial software and integrates features such as demand response modelling, the correlation between reserve requirements and the technology mix, and hydrogen as an energy vector. This representation is applied to the Spanish electricity system to assess the consistency of the targets of the national energy strategy. Several scenarios of costs, demand and variation of other parameters are simulated to analyse their relative influence on the solution of minimum cost, especially assessing the sensitivity of energy storage capacity. The simulation results show that the Spanish goals for decarbonising the electricity system are based on optimistic assumptions. Also, energy storage will play a more important role than expected, and the use of hydrogen for energy storage is only needed for a 100% penetration of renewable energies.

Near Neutral Aqueous Fe-Cr Complex Flow Battery

A redox-flow battery (RFB), as schematically shown is a unique type of rechargeable battery in which the electrochemical energy is stored in soluble redox couples contained in electrolyte tanks, and the electrical energy and the chemical energy are converted back and forth inside a device called “stack”. This unique structure successfully separates the power (stack) and the energy (electrolyte) of the battery system and can be economically designed for long-duration energy storage applications. While vanadium flow batteries have achieved initial commercial deployments, the cost of a four-hour system at deployment-scale is still more than $300/kWh, more than 50% of which comes from the cost of the energy storage media – Vanadium element. DOE’s multiple programs clearly indicates that future capital cost reductions will require replacing vanadium with lower cost raw materials to approach the $100/kWh targets required for wider-scale deployment of energy storage systems. Since 2018, attracted by its low electrolyte cost, our team have been working on the legendary Fe-Cr redox flow battery system, which was first invented by Dr. Lawrence Thaller of US NASA in 1975, to develop a low[1]cost flow battery product. The energy storage capacity decay caused by H2 generation, which comes from the negative electrode due to the low standard potential of Cr 2+ /Cr 3+ , makes it not practical for long-term energy[1]storage operations. After two years’ research, we have successfully developed an advanced Fe-Cr redox flow battery system. In this system, no capacity decay over continuous charge and discharge operation has been successfully achieved by an extremely low H2 generation design and a unique capacity recovery technology using a reductant and a homogeneous catalyst. Continuous operation of a test stand using a kW-scale stack and 100L electrolyte for a total 1000 cycles has been successfully achieved. Related information and results were published in the granted US patents US 10,826,102 and US 10,777,836, and the US patent applications 20200373594, 20200373595, 20200373600, 20200373601. During our previous development of the advance Fe-Cr redox flow battery, we discovered that the stability and electrochemical activity of Fe- and Cr-containing species in the aqueous solution can be remarkably improved by complexing them with some ligands. The acidity of this novel electrolyte solution is much weaker than that of the traditional Fe-Cr flow battery system, i.e., ~0.1M vs. >2M, which largely reduces the corrosivity of the electrolyte and allows for wider applications of this system with minimal environmental impact, especially for residential users and small-scale commercial and industrial users. Several different complexing ligands were identified. All showed very stable performance and low side reactions. Up to now, the test has been continuously carried out for more than three months and more than 500 cycles, using a kW-scale stack and 100 L electrolyte solution. Much-improved electrochemical reactivity of the Fe- and Cr-complex also eliminates the need for metal catalysts for the Cr 2+ +e ↔ Cr 3+ reaction, significantly improved the stability of the system for long-term operation.

Uncovering the dynamics and uncertainties of substituting coal power with renewable energy resources

China aims to curb “peak carbon dioxide emission” by 2030 and achieve “carbon neutrality” by 2060, which are undoubtedly ambitions and challenging objectives. An important way to achieve this goal is to substitute coal power plants (CPPs) with renewable energy power plants (REPPs). In this context, this study establishes a government-CPPs-REPPs evolutionary game framework combined with the Hotelling model to uncover the dynamics and uncertainties in substitution. The results are as follows: (i) the substitution goes through three stages with significant heterogeneity: the initial, intermediate, and mature stages. The strategy profiles in the mature stage are an ideal choice, and it is essential to strengthen the willingness of power plants to adopt carbon capture and storage (CCS) and energy storage technology. (ii) The electricity market share evolves with the changing strategies mix, and the competition shows a variation state of “inefficient–Prisoner's dilemma–Pareto optimality” in three stages. Additionally, renewable energy is the main power source at the mature stage. (iii) Furthermore, it is necessary to decrease the adoption cost of energy storage and CCS technology and maintain a reasonable subsidy phase-out level. Finally, effective policies of the feed-in tariff and carbon market tend to facilitate CCS retrofitting and energy storage system deployment.

Decentralized approach for security enhancement of wind‐integrated energy systems coordinated with energy storages

Wind speed fluctuations in wind-integrated energy systems render the need for the fast and proper response of the conventional thermal generating units. This is while ramping constraints of these units as the backbone of the traditional power generation cycle depreciate their response, which poses a serious security challenge. This article is aimed at enhancing the security of multiarea wind-integrated energy systems by the coordinated deployment of energy storage systems (ESSs). To realize a practical model, a probabilistic reformulation of decentralized security-constrained optimal power flow by taking into account the thermal units' ramping constraints is developed, which tackles the uncertainties of wind speed fluctuations through a proper provision of ramping requirements by ESSs. Moreover, the optimality condition decomposition algorithm is used to solve security-constrained optimal power flow at each area of the energy system in a decentralized manner. Furthermore, to reduce the computational burden, a contingency filtering approach is employed that filters the uncritical conditions during the solution process. Different scenarios of transmission line and generator outages are explored by linear outage factors, including the line outage distribution factor and the power transfer distribution factor. In the established model, the value of loss of load and the value of wind curtailment factors are employed to reflect the economic impact of load shedding and wind energy curtailment. For supplying the lost power in generation outages, the participation factor of the connected sources is modified, which considers the remained generation capacity of sources. To assess the efficiency of the proposed model, the New England 39-bus testbed is put under extensive investigation. The results are discussed in depth.

Near Neutral Aqueous Fe-Cr Complex Flow Battery: Reducing Electricity Storage Cost to < $100/kWh

A redox-flow battery (RFB), as schematically shown is a unique type of rechargeable battery in which the electrochemical energy is stored in soluble redox couples contained in electrolyte tanks, and the electrical energy and the chemical energy are converted back and forth inside a device called “stack”. This unique structure successfully separates the power (stack) and the energy (electrolyte) of the battery system and can be economically designed for long-duration energy storage applications.While vanadium flow batteries have achieved initial commercial deployments, the cost of a four-hour system at deployment-scale is still more than $300/kWh, more than 50% of which comes from the cost of the energy storage media – Vanadium element. DOE’s multiple programs clearly indicates that future capital cost reductions will require replacing vanadium with lower cost raw materials to approach the $100/kWh targets required for wider-scale deployment of energy storage systems. Since 2018, attracted by its low electrolyte cost, our team have been working on the legendary Fe-Cr redox flow battery system, which was first invented by Dr. Lawrence Thaller of US NASA in 1975, to develop a low-cost flow battery product. The energy storage capacity decay caused by H2 generation, which comes from the negative electrode due to the low standard potential of Cr2+/Cr3+, makes it not practical for long-term energy-storage operations. After two years’ research, we have successfully developed an advanced Fe-Cr redox flow battery system. In this system, no capacity decay over continuous charge and discharge operation has been successfully achieved by an extremely low H2 generation design and a unique capacity recovery technology using a reductant and a homogeneous catalyst. Continuous operation of a test stand using a kW-scale stack and 100L electrolyte for a total 1000 cycles has been successfully achieved. Related information and results were published in the granted US patents US 10,826,102 and US 10,777,836, and the US patent applications 20200373594, 20200373595, 20200373600, 20200373601.During our previous development of the advance Fe-Cr redox flow battery, we discovered that the stability and electrochemical activity of Fe- and Cr-containing species in the aqueous solution can be remarkably improved by complexing them with some ligands. The acidity of this novel electrolyte solution is much weaker than that of the traditional Fe-Cr flow battery system, i.e., ~0.1M vs. >2M, which largely reduces the corrosivity of the electrolyte and allows for wider applications of this system with minimal environmental impact, especially for residential users and small-scale commercial and industrial users. Several different complexing ligands were identified. All showed very stable performance and low side reactions. Up to now, the test has been continuously carried out for more than three months and more than 500 cycles, using a kW-scale stack and 100 L electrolyte solution. Much-improved electrochemical reactivity of the Fe- and Cr-complex also eliminates the need for metal catalysts for the Cr2+ +e ↔ Cr3+ reaction, significantly improved the stability of the system for long-term operation.

Exploring and Predicting the Knowledge Development in the Field of Energy Storage: Evidence from the Emerging Startup Landscape

The distribution and deployment of energy storage systems on a larger scale will be a key element of successfully managing the sustainable energy transition by balancing the power generation capability and load demand. In this context, it is crucial for researchers and policy makers to understand the underlying knowledge structure and key interaction dynamics that could shape the future innovation trajectory. A data-driven approach is used to analyze the evolving characteristics of knowledge dynamics from static, dynamic and future-oriented perspective. To this end, a network analysis was performed to determine the influence of individual knowledge areas. Subsequently, an interaction trend analysis based on emergence indicators was conducted to highlight the promising relations. Finally, the formation of new knowledge interactions is predicted using a link prediction technique. The findings show that ensuring the energy efficiency is a key issue that has persisted over time. In future, knowledge areas related to digital technologies are expected to gain relevance and lead the transformative change. The derived insights can assist R&amp;D managers and policy makers to design more targeted and informed strategic initiatives to foster the adoption of energy storage solutions.

Comparative Study of Energy Storage Systems (ESSs)

Renewable energy (RE) resources have shown impressive growth globally, as these sources do not provide enough amount that is readily adaptable to consumer needs, it can rarely allow an immediate response to demand. However, intermittency in RE supply (RES) sources, combined with fluctuating demand shifts over time, has caused a high risk of sustaining system reliability to provide customers with sufficient supply. The excess energy produced by RESs can be stored in a myriad of ways and used later during shortages or intermittent periods. This study was carried out to understand how to provide energy storage to create a future built environment where RE systems play an essential role. There are different types of a storage system with different characteristic, parameters, and costs. This paper highlights the chronology, classification, characteristic, comparison, and assessment of ESSs and energy storage systems deployment.

Optimal Allocation and Control of EV Energy Storage in Microgrids

Next Generation smart grid (SG) systems blend legacy power system networks and the latest state-of-the-art ICT technologies to ensure the efficiency, robustness as well as reliability of the former (power systems). The duplex flow of both information and energy enhances energy supply and de-mand response, as well as SG-related innovative business-oriented applications and services. Renewable generators (RGs) and Electric Vehicles (EVs) are becoming prominent in any SG setup as they promote environmental friendliness. The presence of both necessitates the optimal allocation of dis-tributed renewable generation (DRG) and energy storage sys-tems (ESS) at both SG and microgrid (MG) levels. In that way, grid stability will be always ensured. The paper describes and discusses an optimized ESS deployment approach for serving EVs (as they are one of the largest consumers of stored energy) and DRGs. Careful consideration of the state of the ESS is also considered by developing and applying a dynamic capacity adjustment algorithm to deal with the none-smooth cost func-tions. The proposed cost function takes into consideration the operation as well as investment cost minimization concurrently. The matrix real-coded genetic algorithm (MRCGA) is used to minimize the cost function of the system while constraining it to meet the customer demand, as well as the security of the system overall. The computational simulation results are presented to verify the effectiveness of the proposed method. The electricity network model is simplified using a virtual subnode concept to alleviate the computational load burden of a node's agent. Simulation results demonstrate the feasibility and stability of this dispatch strategy. Overall, our proposed framework and obtained results set a benchmark for the realization of agent-based coordination algorithms to solve the optimal dispatch problem

Optimized Energy Storage System Configuration for Voltage Regulation of Distribution Network With PV Access

With the large-scale integration of renewable energy such as wind power and PV, it is necessary to maintain the voltage stability of power systems while increasing the use of intermittent renewable energy sources. The rapid development of energy storage technologies permits the deployment of energy storage systems (ESS) for voltage regulation support. This paper develops an ESS optimization method to estimate the optimal capacity and locations of distributed ESS supporting the voltage regulation of a distribution network. The electrical elements of the network integrated with PV and ESS are first modelled to simulate the voltage profile of the network. Then an improved multi-objective particle swarm optimization (PSO) algorithm is employed to minimise a weighted sum of the overall nodal voltage deviation from the nominal level across the network and across the time horizon and the energy capacity of ESS reflecting the associated investment. The improved PSO algorithm adaptively adjusts the inertia weight associated with each particle based on its distance from the best known particle of the population and introduces the cross-mutation operation for a small distance to avoid falling into local optimal solutions. Then the dynamic dense distance arrangement is taken to update the non-inferior solution set and indicate potential global optimal solutions so as to keep the scale and uniformity of the optimal Pareto solution set. To mitigate the impact of decision makers’ preference, the information entropy based technique for order of preference by similarity to ideal solution is used to select the optimal combination of the ESS access scheme and capacity from the Pareto solution set. The proposed ESS optimization method is tested based on the IEEE 24-bus system with additional imports from high-voltage power supply. The voltage profile of the network simulated without the ESS or with the random or optimized ESS placement is compared to illustrate the effectiveness of the optimized ESS in performing voltage regulation under normal operation and supporting emergency power supply during high-voltage transmission failures.

Impedance Methods for Analyzing Stability Impacts of Inverter-Based Resources: Stability Analysis Tools for Modern Power Systems

Power systems around the world are undergoing a major transformation because of the increasing shares of renewable energy, growing deployment of energy storage systems, proliferation of distributed energy resources, electrification of other sectors, and so on. In the United States, wind and solar provided almost 10% of electricity in 2019. The U.S. Energy Information Administration, in its 2020 Annual Energy Outlook, forecasted that the share of electricity from renewables will reach 38% by 2050, of which more than 80% will come from wind and solar. Wind and solar, along with battery energy storage systems, interface with the grid using power electronic inverters; hence, they are collectively referred to as inverter-based resources (IBRs). The increasing annual share of electricity from IBRs in a power system means that during more times of the year, the system will operate at a much higher concentration of IBRs. Figure 1 presents the hourly share of wind and solar generation in the Electric Reliability Council of Texas (ERCOT) system in Texas in 2019. While the annual wind share was at 20%, the instantaneous percentage share was much higher. Moments of high shares of IBRs (g50%) will continue to grow as more IBRs will be deployed in a power system.