Energy Storage Configuration Research Articles

Application of Double-Layer Optimization Model in Energy Storage Configuration of Distributed Power

Application of Double-Layer Optimization Model in Energy Storage Configuration of Distributed Power

Enter Paper Title]PV Based Hybrid Energy Storage for DC Motor Applications

This paper presents a PV based hybrid energy storage(HES) configuration for DC motor application. A three port bidirectional buck boost converter is used to interface both PV and HES with the dc link. A hybrid energy storage system as a combination of battery and supercapacitor is used for the better performance by balancing the power fluctuations due to both PV and load disturbances with increased life time and reduced size of battery. Power balance along with maximum power point operation of PV, Inherent PV voltage boosting and supercapacitor voltage regulation with a simple control structure having lesser number of sensors is used. The proposed model is designed and simulated in MATLAB/SIMULINK environment.

Optimal configuration of hybrid energy storage in integrated energy system

The integrated energy system (IES) with combined heat and power (CHP) generation units is regarded as an effective way to improve energy efficiency. The installation of hybrid energy storage can further improve the system’s economy. This paper proposes an optimal sizing method for electrical/thermal hybrid energy storage in the IES, which fully considers the profit strategies of energy storage including reducing wind curtailment, price arbitrage, and coordinated operation with CHP units, etc. The minimum energy cost of the system in the energy storage life cycle is taken as the objective function. Meanwhile, the power constraints connected with the distribution network/district heating network and the two-part price mechanism are considered. The results in the case study show the effectiveness of the approach.

Double-layer energy management system based on energy sharing cloud for virtual residential microgrid

The idea of energy sharing can contribute to achieving the goal of resource optimization by redistributing and sharing idle energy assets. How to design an appropriate energy management strategy in the energy sharing environment has been the focus of intensive research in energy sharing field. In this paper, a new effective double-layer energy management system (EMS) based on the energy sharing cloud (ESC) is developed for a virtual residential microgrid (VRMG). The proposed ESC can be regarded as an open energy sharing environment, where the cloud platform helps cloud users build their VRMGs by providing energy services including renewable energy sources (RESs) generation and energy storage. The mathematical model of the VRMG is formulated, and the energy service prices for RESs generation and energy storage are monthly set separately. Moreover, considering the changes in household load and RESs generation, an energy management strategy of double-layer EMS is designed. The upper-layer EMS helps VRMG obtain the monthly optimal capacity configuration of RESs and energy storage, and the lower-layer EMS realizes the daily electricity scheduling optimization for the VRMG whose objectives are to minimize the total operational cost and maximize the electrical comfort level. Simulation studies demonstrate that the proposed energy sharing mechanism can meet the changing energy needs of the cloud user, and numerical experiments also confirm the performance and effectiveness of the proposed double-layer EMS.

Thermal storage analysis of a foam-filled PCM heat exchanger subjected to fluctuating flow conditions

A dynamic heat transfer model is developed to investigate the transient thermal storage characteristics of a heat exchanger with foam-filled phase change material (PCM) under the fluctuating flow conditions. The thermal energy storage (TES) configuration of double pipe is considered, while using the highly porous metal foam to intensify the heat transfer in both the PCM and heat transfer fluid (HTF) regions. The paraffin RT50 is used as the PCM and water is selected as the HTF. The energy transport between the inner and outer pipes is thoroughly taken into account. The Darcy-Forchheimer equation is adopted to model the fluid flow through metal foam, and the enthalpy-porosity method is employed to simulate the phase change process within the PCM/foam composite under the local thermal non-equilibrium (LTNE) condition. The performance of heat exchanger during the charging process is firstly predicted under steady HTF flow, and then the effects of fluctuating inlet temperature and velocity are examined respectively. In the case of steady flow, compared with the pure PCM case, inserting metal foam in both the PCM and HTF regions shortens the melting time by 93.6% and augments the heat storage rate by 9 times. Fluctuation in the inlet temperature leads to a visibly oscillating variation in the PCM temperature and heat storage, which are 15 K, 65 kJ at a fluctuation amplitude of 30 K and 17 K, 105 kJ at a periodicity of 400 s. However, fluctuation in the velocity has no considerable influence. The heat exchanger with lower porosity foam presents more sensitive to the fluctuating inlet temperature.

Study of optimal system configuration and charge-discharge strategy of user-side battery energy storage

Study of optimal system configuration and charge-discharge strategy of user-side battery energy storage

Research on Hybrid Energy Storage Configuration in Grid Wind Power Scheduling Tracking Under Statistics and Frequency Decomposition

AbstractThe low accuracy of wind power scheduling influences the grid dispatch adversely, increasing the demand for spinning to reserve capacity and obstructing the grid frequency regulation. Considering the throughput characteristics of energy storage system, which can be used to compensate for wind farm power scheduling deviations, and smooth the grid power fluctuations, the hybrid energy storage (HES) is employed to enhance the dispatch ability of wind power generation. As one of the key techniques, desirable energy storage capacity configuration (ESCC) and control methods would accelerate the application of energy storage in the field of new resource. Combined with statistics and frequency decomposition of scheduling power deviation, HES capacity configuration and online dynamic power allocation method are proposed. First, by analysis of grid assessment indexes of wind power, scheduled wind power data are produced by improved adaptive error factor correction particle swarm optimization back-propagation neural network (AEFC-PSO-BPNN) prediction followed by wavelet packet smooth (WPS). After comparing with actual power, scheduling deviation statistics and frequency decomposition are applied in capacity and power configuration of energy storage, as well as dynamic power distribution control. With wind/storage simulation platform, then, feasibility of energy storage embedded in grid wind power scheduling deviation, regulation is verified under several combined methods, and the proposed ESCC methods are tested in application case by grid wind power indexes of root-mean-square error rate (RMSE), average volatility (AV), maximum throughout power and current (MTP, MTC), actual supercapacitor (SC), battery consumption capacity, and the number of crossings of state of charge (SOC) of HES. Finally, analyses and comparison of energy storage capacity requirements are carried out on different scheduling deviation control methods so as to explore the significant factors influencing capacity allocation. Applying these methods can improve the scheduling accuracy of grid wind power, reduce power fluctuations at the power common connected (PCC) point, and minimize the impact of accessed wind power to the grid as much as possible.

Analysis of tubular receivers for concentrating solar tower systems with a range of working fluids, in exergy-optimised flow-path configurations

Central tower concentrating solar power (CSP) systems typically focus solar radiation upon a tubular solar receiver where radiation is absorbed and then transferred, by conduction and convection, into a heat transfer fluid. In this paper, a range of heat transfer fluids are compared, using energy and exergy analysis, and varying the tube diameter, tube wall thickness, and tube-bank flow configuration. The model optimises exergy efficiency including pumping work, assuming uniform flux, and neglecting the effects of thermal stresses, circumferential tube temperature variations and cost. Suitable temperature and pressure conditions are chosen for each fluid, based on a realistic configuration of an applicable thermal energy storage (TES) and power block (PB). The examined heat transfer fluids are molten salt (60% NaNO3, 40% KNO3), liquid sodium, supercritical carbon dioxide (sCO2), air, and water/steam. Results showed that liquid sodium at an elevated (540–740 °C) temperature range performed best, with a solar-to-fluid exergy efficiency of 61%. At a low temperature range (290–565 °C), sodium was still marginally superior to molten salt, even after allowing for some exergy destruction in a sodium-to-salt heat exchanger. Water/steam also performs relatively well in the receiver, although the difficulties of integrating it with large-scale storage make it a challenging heat transfer fluid for an integrated system. Using sCO2 as the heat transfer fluid appears infeasible due to excessively-high pressure stresses on the tubes. Air also appears unsuitable for simple tubular receivers, since poor heat internal transfer results in high losses due to much hotter external surfaces.

Review of Optimal Allocation Methods of Energy Storage in Different Applications of Power System

With widely application of energy storage technology in power system, the function and configuration method of energy storage system (ESS)in different scenarios have become the focus. In the grid side, energy storage can participate in safety accident response, power grid frequency control, peak shaving, power grid upgrading delay and easing transmission line congestion, etc. In the power supply side it is mainly used to improve the power supply flexibility and controllability; In the user side it is mainly used to improve power quality, arbitrage through peak valley, as well as providing uninterrupted power supply to ensure reliability. Due to different application conditions and purpose under different scenarios, energy storage configuration requirements are also vary. So it leads to various configuration method and lack of a unified evaluation index. In this paper, the existing optimization configuration method their respective advantages and disadvantages are analyzed, and then, the ideas, principles and basic evaluation index in common scenario are summarized. It provides reference basis for energy storage optimization in power system.

Research on optimal allocation strategy of multiple energy storage in regional integrated energy system based on operation benefit increment

Wind power generation curve generally has the reverse characteristic with the peak regulation of electricity load curve, which will lead to serious wind abandonment and energy waste. The development of integrated energy systems and energy storage maybe change this predicament. Based on the infrastructure and operation model of regional integrated energy system, this paper studied the allocation priority of cooling, heating, electricity storage and electricity to gas (P2G) system, considering multiple energy complementary and collaborative operation of combined cooling heating and power (CCHP) units and other equipment. Firstly, the operation benefit increment index was proposed to quantify the operation cost variation, also named promotion effect in this paper, between the scenarios of integrated energy system without/with certain form energy storage added. Then, an configuration optimization model of multiple energy storage devices based on operation benefit increment was put forward. By employing an industrial district integrated energy system in northern China as the study case, the operation scheduling scheme and the priority of energy storage configuration were solved by the optimization strategy proposed in this paper. And the promotion effects of different energy storage configurations were analyzed from the viewpoint of operation economy of the integrated energy system. The results show that the abandoned wind power and the cost of environmental pollution control are reduced in the integrated energy system with four kinds of energy storage. And the economic efficiency is greatly improved.

Research on capacity planning and optimization of regional integrated energy system based on hybrid energy storage system

Some regional integrated energy systems (RIES) have installed equipments such as wind turbine and photovoltaic, but the fluctuation of these intermittent power supply is large, resulting in a certain amount of energy waste. Because energy storage can improve the utilization rate of renewable energy, this paper establishes a storage capacity expansion planning model considering multiple functions of hybrid energy storage in the RIES. In this model, the wavelet packet decomposition method is used to reasonably decompose the high-frequency fluctuation and low-frequency fluctuation of renewable energy to achieve the function of stabilizing fluctuation. Meanwhile, an operation strategy for hybrid energy storage to participate in demand response is proposed. Rain flow counting method is used to research the life of hybrid energy storage system, which improves the accuracy of energy storage annual cost calculation. In the Simulation and Analysis section, the genetic quantum algorithm is used for simulation and analysis of the role and benefits of hybrid energy storage. The simulation results show that the benefit of hybrid energy storage in capacity expansion construction is increased by 10.4%, and when the electricity and gas prices fluctuate by ±20%, the hybrid energy storage configuration proposed in this paper has a stable advantage in more than 95%.

Numerical analyses of concrete thermal energy storage systems: effect of the modules’ arrangement

This paper is focused on modularized concrete sensible thermal energy storage systems with thermal oil as heat transfer fluid; the thermal storage systems have been conceived to be integrated into a concentrated solar power plant. This work is mainly focused on the effect of the modules’ arrangement on the overall performance of the thermal energy storage system. Series and parallel arrangements are investigated, to determine the most performant solutions in terms of exchanged thermal energy as a function of the main operating conditions: oil mass flow rate and pressure drop, both in heating and cooling phase. Two different boundary conditions are considered: adiabatic and diabatic external walls. The simulations are carried out using an extended version of a model proposed by the present authors for a single concrete block, that was validated with experimental data. The exchanged thermal energy, the oil mass flow rate, the pressure drops, and the duration of the process are changed to evaluate the storages under different operating conditions. The best thermal energy storage configuration is determined by a thermal energy assessment: it coincides with the first one that reaches the asymptotic values with the minimum number of elements. Furthermore, in the diabatic case, the loss heat flux toward the environment has a significant role and highlights the differences between charging and discharging phases, its presence contributed to a more aware choice of the most suitable and performant modularized system.

Calculation and analysis of the storage capacity configuration of Shanxi power grid based on time series simulation

In recent years, with the energy transformation and the continuous innovation of new energy technology, the installed capacity of new energy continues to increase, the high proportion of new energy access increases the peak pressure of the power grid, but also increases the possibility of de-electric power. As a key solution, energy storage and wind power and other new energy in-depth integration, can effectively improve the power grid adjustment capacity, to ensure the benefits of new energy generation. Using the time series production simulation method, aiming at the utilization rate of new energy, this paper calculates the principle of energy storage configuration in different regions of Shanxi Province, and provides theoretical support for the analysis of energy storage configuration in Shanxi Province.

Thermal performance of structured packed bed with encapsulated phase change materials

Packed bed latent heat storage system with simple construction and efficient heat transfer has been extensively applied in the field of renewable energy. This study aimed to select a proper structured packing format by comparing the thermal performance of different structured packed bed thermal energy storage (TES) configurations, with encapsulated paraffin as the phase change material (PCM). The 3D numerical models of the structured packed beds were constructed, and the numerical results are in agreement with the experimental ones. The performance indexes, including the average heat storage rate, total energy, discharging time and construction cost, were evaluated under consistent working condition. The analysis results indicate that the packed bed TES configuration with face centre cubic packing (FCC) possesses superior characteristics, such as high charging rate, low investment cost, large total heat storage energy and stable output temperature, compared with that with body center cubic packing or simple cubic packing. A detailed parametric investigation of the packed bed TES configuration with FCC is implemented to analyse the effect of Reynolds number (Re), inlet temperature and Prandtl number (Pr) of the heat transfer fluid (HTF). Results showed that the uniform extraction of heat is obtained by the packed bed with small inlet Re. The larger the temperature difference between PCM and HTF is, the faster the discharging rate is and the bigger the total heat recovery energy is. By selecting water, fuel oil JP-4, ethylene glycol and hydraulic oil as HTFs, the change in the HTF's Pr is determined to be irrelevant to the thermal characteristic variations of the structured packed bed TES configuration, whereas the thermal conductivity of the HTF positively affects the heat transfer inside the structured packed bed.

Optimal configuration of energy storage for remotely delivering wind power by ultra-high voltage lines

Abstract Power generated by large-scale wind farms in northwest China needs to be remotely delivered by ultra-high voltage lines (UHVs) before consumption. However, fluctuation and intermittency of wind power output results in high costs and low efficiency of transmission. This study proposes a novel optimal model and practical suggestions to design an energy storage involved system for remotely delivering of wind power. Based on a concept model of wind-thermal-storage-transmission (WTST) system, an optimization model is established to determine optimal configurations of the system. As validated by a case study, the model is capable of determining installed capacities of wind power plants, thermal power plants, pumped hydro storage stations, and maximum transmission capability of UHVs; and it can be fast solved by mixed integer programming. According to the results of case simulation, the best configuration can significantly reduce wind curtailment rate and improve operational efficiencies of UHVs by load shifting before and after power transmission. Specifically, improving energy storage capacity and remolding thermal power plants to be flexible ones are feasible ways to realize the objectives, which are vital to increase the penetration rate of wind power in China.

Two‐stage robust optimisation of user‐side cloud energy storage configuration considering load fluctuation and energy storage loss

Recently, many industrial users have spontaneously built energy storage (ES) systems for participation in demand-side management, but it is difficult for users to benefit from participating in demand response (DS) because of the expensive costs of ES construction. Therefore, this study proposes a cloud ES (CES) architecture that can reduce these costs by utilising users' complementary load characteristics and the scale benefits resulting from large-scale construction of ES equipment. Considering the DR and the uncertainty of the user load, this study applies two-stage robust optimisation to solve for the optimal configuration of CES. The proposed optimisation model is verified using the load data of an industrial park in Jiangsu Province, and the results clearly indicate that the proposed CES can be more beneficial than self-built distributed ES during the warranty period. The robust configuration results can be applicable even when the load changes within the maximum and minimum range.

Research on Energy Storage Capacity Allocation Technology of PV-Storage Microgrid for Balancing Source-Load Power

The low matching degree of photovoltaic output and load in the pv-storage microgrid will reduce the reliability of its power supply. Therefore, it is necessary to configure a certain capacity energy storage device to support source-load balance.This article first analyzes the impact of different load configurations and application scenarios on energy storage configuration, and then proposes an energy storage capacity configuration scheme with the minimum operating cost of the microgrid as the objective function and the constraints of the minimum power fluctuation in the network, and uses an improved particle swarm algorithm solve the solution. Finally, a numerical example is used to verify that the solution can stably support the source-load balance in the microgrid, reduce the power exchange at the common connection point of the microgrid, and improve the microgrid’s own power supply capacity.

Fuzzy Logic Energy Management Strategy of a Multiple Latent Heat Thermal Storage in a Small-Scale Concentrated Solar Power Plant

Latent heat thermal energy storage (LHTES) systems allow us to effectively store and release the collected thermal energy from solar thermodynamic plants; however, room for improvements exists to increase their efficiency when in operation. For this reason, in this work, a smart management strategy of an innovative LHTES in a micro-scale concentrated solar combined heat and power plant is proposed and numerically investigated. The novel thermal storage system, as designed and built by the partners within the EU funded Innova MicroSolar project, is subdivided into six modules and consists of 3.8 tons of nitrate solar salt kNO3/NaNO3, whose melting temperature is in the range 216 ÷ 223 °C. In this study, the partitioning of the storage system on the performance of the integrated plant is evaluated by applying a smart energy management strategy based on a fuzzy logic approach. Compared to the single thermal energy storage (TES) configuration, the proposed strategy allows a reduction in storage thermal losses and improving of the plant’s overall efficiency especially in periods with limited solar irradiance. The yearly dynamic simulations carried out show that the electricity produced by the combined heat and power plant is increased by about 5%, while the defocus thermal losses in the solar plant are reduced by 30%.

Influence of centralized and distributed thermal energy storage on district heating network design

Future district heating networks have to be flexible enough to absorb the heat load variations and additional heat production variations imposed by increasing intermittent renewable energy sources. Thermal energy storage is a proven, efficient and cost effective technology to provide such flexibility. A centralized hot water storage tank near the source is the most common thermal energy storage configuration in district heating systems today. Though this configuration provides flexibility and reduces peak load capacity, it doesn’t impact the network peak transport capacities since the heat still needs to be transported from the source location during peak demand periods. This paper investigates the benefits of placing thermal storage tanks in the distribution networks to decrease the network peak transport capacities and balance the heat loads locally. Building heat demand data is extracted using the open source street level gas consumption data and appropriate heat demand profiles are chosen based on the building type. A case study comparing centralized and distributed storage is carried out using these input data with Comsof Heat, an automated district heating network routing and planning tool. The effect of these storage configurations on total network cost is compared and several scenarios are explored with different storage sizes. The case study results show that centralized storage can reduce the total network investment cost by 4%, the substation level storage can reduce the costs by 5% and the building level storage can reduce the costs up to 7% for the given inputs.

Optimal configuration of the energy storage system in ADN considering energy storage operation strategy and dynamic characteristic

To meet the needs of energy storage system configuration with distributed power supply and its operation in the active distribution network (ADN), establish the dynamics of the all-vanadium redox flow battery energy storage system (BESS). On this basis, an energy storage operation of ADN strategy is proposed to stabilise the power fluctuation of the system. The energy storage configuration model with optimising objectives such as the fixed cost, operating cost, direct economic benefit and environmental benefit of the BESS in the life cycle of the energy is constructed, and the energy storage installation capacity, power and installation position are used as decision variables, which are solved by the dynamic programming algorithm. On the basis of case 33 and case 69 node examples and typical daily load and distributed generations output curve, the simulation analysis is carried out to obtain the optimal configuration result. At the same time, the system tie-line power and the dynamic characteristics of the energy storage system before and after the installation of the energy storage device are obtained. The simulation results show the validity of the model.