Solar Energy Storage System Research Articles

Model‐based control of a VSC‐based power generator with synthetic inertia provision in an isolated micro‐grid

Distributed energy resources such as solar photovoltaic, wind and energy storage systems are increasingly being utilised within isolated and grid-connected microgrids. Their integration has prompted the move towards more advanced coordinated control for flexible, efficient and secure operation of microgrid-based power systems. This study presents a new power control method based on a canonical inverse model and implied synthetic inertia (SI), which is implemented on a voltage source converter-based power generator (VSC-PG) for frequency response support. The control method augments a traditional power controller whilst the SI technique is blended with a new switching mechanism which enhances the performance of the VSC-PG when it is utilised with SI provision capability. The switching mechanism acts only when necessary, without contradicting the main frequency regulating sources. For assessment, the above method and SI technique have been designed and modelled for a 630 kVA VSC-PG with DC-link battery bank. The VSC-PG was connected within an isolated/remote microgrid formed by an 11 kV feeder, 1 MVA diesel generator and variable load. The performances of the proposed power controller and SI provider have been tested and analysed using detailed Matlab/Simulink simulations and found to compare favourably with methods published in the literature.

Multi-level interactive unit commitment of regional power system

Distributed energy resource (DER) including wind power, solar energy and energy storage system (ESS) are connected to the active distribution network (ADN) in various combination ways, which makes the distribution network have interaction. As a bridge connecting the transmission grid (TG) and micro grid (MG), ADN breaks the traditional operation pattern of TG + ADN + MG. Considering the physical connections and shared information among TG, ADN and MG, this paper proposes a decentralized and parallel analytical target cascading (ATC) algorithm for interactive unit commitment (UC) implementation in regional power systems. To explore the synergistic ability of the TG + ADN + MG coping with uncertainties of DER, i.e., wind power, the primary and secondary frequency regulation of TG are implemented to cope with uncertainties. Furthermore, the distributional uncertainty of wind power is well modeled by data driven, which is proposed in our previous work (Zhang et al., 2019) [1]. Both the startup/shutdown variables of the thermal units and the variables in TG + ADN + MG are integrated into the multi-level interactive UC model to optimize simultaneously, thus realizing the optimal goal of the whole network, resources complementary and optimal allocation of power system. An improved 6-bus system is used to test the proposed model, the numerical results show that the proposed decentralized algorithm is a fully parallelized procedure. And it also demonstrates the parallel implementation significantly enhances computations efficiency of the ATC algorithm.

Comparison of economic model predictive control and rule‐based control for residential energy storage systems

This study quantifies the benefits of implementing model predictive control on residential solar PV and energy storage systems considering a time-of-use demand tariff, feed-in tariff and varying PV system sizes and battery life-cycle costs. The control system analysed makes use of economic model predictive control (EMPC) whereby the objective function is directly tied to the economics of the system. Using residential load and PV data from an Australian distribution network service provider, the EMPC controller is compared to a rule-based controller, highlighting the benefits of EMPC in regards to annual economic performance and battery energy throughput. The EMPC algorithm is then tested using 10 residential customers at the low voltage feeder level showing the capacity for the EMPC controller to shift peak demand and flatten the aggregated load profile of 30 residential customers.

Performance of Hybrid Filter in a Microgrid Integrated Power System Network Using Wavelet Techniques

Nowadays, the application of distributed energy sources (DES) has been extensively employed to serve the power system by supplying the power into the grid and improving the power quality (PQ). Therefore, DES is one solution that can efficiently overcome the energy crisis and climate change problems. The DES, such as solar photovoltaic (PV), wind turbine (WT), and battery energy storage systems (BESS), are incorporated to form the microgrid (MG), which are interfaced with the power system. However, interfacing MG to the power system is undoubtedly a big challenge. Therefore, more focus is required on the control strategy to control the MG with the power system. To address the PQ problems, a controlled MG integrated with a hybrid shunt active power filter (HSAPF) is provided in this work. For controlling the MG integrated HSAPF, different control strategies are applied. In this work, a learning-based incremental conductance (LINC) technique is used as a maximum power point tracking (MPPT) for tracking the maximum power in PV and WT. The voltage source inverter (VSI) of HSAPF is controlled using a wavelet-based technique with a synchronous reference frame (SRF). The main focus is to improve the PQ by compensating the harmonics and regulating the reactive power in both grid-interactive and islanded condition and also supply continuous and adequate power to the non-linear load. The power system model has been developed with MATLAB/Simulink tool, which shows the efficiency of the proposed method. The results obtained have been satisfactorily under various operating conditions and can be validated further using the real-time dSPACE.

Numerical modeling and performance comparison of high-temperature metal hydride reactor equipped with bakery system for solar thermal energy storage

The current study provides an optimal design strategy for the metal hydride reactor for the thermal energy storage system for solar bakery applications. The sensitivity analysis of the annular truncated hollow conical fins type reactor was conducted by using COMSOL Multiphysics 5.3a software. The gravimetric exergy output rate and exergy output of different designs were compared. It was found that the optimal geometric parameters and operating conditions for the annular truncated hollow conical fins type reactor are fin angle (θ)=20°, fin radius (Rf) = 0.07 m, number of fins (Nf)= 32 and fin spacing (Sf) = 0.02 m, fin thickness (thf) = 0.008 m, hydrogen supply pressure (Pin, H2) = 5 MPa and inlet heat transfer fluid velocity (VHTF,in) = 20 m/s. Finally, it was concluded that the Deign IV is the most favorable design, which has a uniform reaction, faster reaction time (15,000 s), and higher values of gravimetric exergy output rate and exergy output (1.23 W/kg, 0.028 kW).

Thermal performance of a coupled solar parabolic trough collector latent heat storage unit for solar water heating in large buildings

This paper deals with the feasibility of using a coupled solar parabolic trough collector-latent heat thermal energy storage system for large buildings hot water production. A detailed dynamic thermal model is developed to investigate the thermal performance of the studied system under realistic meteorological conditions. The validation of the developed model is carried out through comparing numerical results with existing numerical and experimental data and a good agreement is obtained. Three kinds of phase change materials are studied and the optimal design of the storage system is determined for weather conditions of a typical summer day in the south of France. Both charging and discharging processes of the latent heat storage system are investigated and obtained results show that using the storage system is suitable to provide hot water all the night. These results indicate also that for a mass flow rate of 1800 l/h, using RT-55 as phase change material in the studied system is preferable compared to RT-42 and RT-65. Finally, it is concluded that using the proposed system with RT-55 as storage medium is suitable for large buildings hot water production and the system is able to produce hot water within the ranges of 85–36 °C and 63-38 °C, during daytime and nighttime operation, respectively. • A novel solar water heater for large buildings with latent heat storage is proposed. • An optimal design of the solar concentrator-heat storage system is determined. • PCM type and water mass flow have a significant influence on water temperature. • PCM RT-55 is suitable in this system compared to RT-42 and RT-65. • Hot water is produced all the night within the range 63–38 °C.

Systems approach to end-of-life management of residential photovoltaic panels and battery energy storage system in Australia

Understanding the complexities around managing the end-of-life (EoL) residential solar photovoltaic (PV) and battery energy storage systems (BESS) is a precursor to a better decision-making process that mitigates unintended product life-cycle impacts. In this paper, a participatory Systems Thinking approach was utilised to build a causal loop diagram (CLD) for this system based on the collective knowledge of stakeholders. The developed CLD was categorised into three sub-systems: (1) waste flows; (2) regulatory aspects; and (3) industry strategies and government incentives. Two main system archetypes were identified in a reflection to the CLD, namely fixes that fail and drifting goals. The identified feedback loops indicate the need to introduce a comprehensive national product stewardship scheme, complimentary landfill restrictions, and provide sufficient incentives to industries for promoting recovery activities within residential PV panels and BESS sectors. An effective waste management system for these renewable energy technologies is most effective if industries are required to participate through regulation which also specifies certain targets, such as product and material recovery rates and establishes a sustainable funding model to meet operational requirements and future needs. The increasingly prohibitive overseas waste export market will require local industries and governments to collaboratively improve domestic recycling capability and capacity. In this light, the failure to build an effective EoL management system for residential PV and BESS will result in valuable and hazardous materials in both technologies to be disposed of in the landfill, stockpiled or illegally dumped; consequently, reinforcing unintended and adverse environmental impacts.

Study on the Development of Measurement Technology for Direct Current Power Systems in Insulation State Using AHRD Algorithm

In this study, an algorithm was developed to represent the insulation state of uninterruptible direct current power supply systems, including circuitry. The existing insulation monitoring system in uninterruptible state was only possible with attachment type devices, but there was no portable inspection equipment at the site. This algorithm is called asymmetric high resistance detection (AHRD), which can compensate for the shortcomings of existing pulse and passive measurement methods, like not being able to measure when both positive and negative electrodes are poorly insulated. The researchers then developed a device that uses this algorithm for the on-site testing of direct current power supply systems, such as solar power generation units and energy storage systems (ESSs). Conversion and estimation formulas were also developed and verified by analyzing the correlation between the measurement values and simulation results of the device’s sensor parameter settings. A standard power supply and standard resistance were used on the newly developed insulation meter to assess it using a lab test and a performance test. Its performance is verified through a comparative analysis between the newly developed insulation meter with the existing insulation monitoring device at an ESS site. Applying the technology proposed in this study at testing sites can enable the verification of the insulation state of circuitry and direct current power supply systems, thereby preventing accidents by ensuring electrical safety.

LFP based Solar Energy Storage System

LFP based Solar Energy Storage System

Establishment of Solar –Wind –Biogas –BESS Based Hybrid Micro-grid

The demand for energy increased due to industrialization, urbanization and population growth. In order to meet the demand for energy, Renewable Energy Sources (RES) are exploited because of its advantages such as developed economic growth and sustainability etc. The micro-grid implemented with isolated distributed generators (DGs) of coordinated operation within it. A hybrid system with all available sources of renewable energy such as solar PV, wind, biogas and battery energy storage system (BESS) for the purpose of 24hrs uninterrupted power supply for the no grid or weak grid regions of rural sectors of India has been recently established in IIEST Shibpur. The design and establishment of solar-wind-Biogas with battery energy storage-based hybrid micro-grid system presented. In this paper design, development and installation of micro-grid consisting of 10kWp solar PV plant, 1kW wind generating system, 35 cubic meter bio digester with 15kVA biogas engine and 1kW, 6kWh VRF battery are described.

High-performance solar flow battery powered by a perovskite/silicon tandem solar cell.

The fast penetration of electrification in rural areas calls for the development of competitive decentralized approaches. A promising solution is represented by low-cost and compact integrated solar flow batteries; however, obtaining high energy conversion performance and long device lifetime simultaneously in these systems has been challenging. Here, we use high-efficiency perovskite/silicon tandem solar cells and redox flow batteries based on robust BTMAP-Vi/NMe-TEMPO redox couples to realize a high-performance and stable solar flow battery device. Numerical analysis methods enable the rational design of both components, achieving an optimal voltage match. These efforts led to a solar-to-output electricity efficiency of 20.1% for solar flow batteries, as well as improved device lifetime, solar power conversion utilization ratio and capacity utilization rate. The conceptual design strategy presented here also suggests general future optimization approaches for integrated solar energy conversion and storage systems.

Improved thermal energy storage behavior of polyethylene glycol-based NEOPCM containing aluminum oxide nanoparticles for solar thermal applications

In the present investigation, a novel composite of Polyethylene glycol (PEG) with molecular weight 10,000 (10 k) and aluminum oxide nanoparticle were prepared for solar thermal energy storage system. A composite of nanoparticles of Al2O3 in different mass fraction (1%, 2%, 3%, 4%, and 5%) and PEG 10,000 was prepared. The thermal properties of these composites and their chemical stability were studied by DSC and FT-IR analysis. The XRD technique was adopted for analyzing the crystallization of prepared composite materials. The TGA curves was also obtained and utilized to check the thermal stability of nano-enhanced organic phase change materials (NEOPCMs). The chemical and thermal reliability was tested by conducting an aging test on an in-housed designed thermal cycler for 1500 melt/freeze cycles. The results show that the thermal properties of the NEOPCMs do not change considerably after the thermal cycle test. An increment of 52.09% in thermal conductivity was found in the developed composite with 5% incorporation of nanoparticles. On the basis of results obtained, it can be ascertained that the composites possess significant thermal properties and are a good candidate for the latent heat thermal energy storage systems having temperature requirement around 60 °C such as solar water heater, etc.

Challenge from Transpower: Determining the effect of the aggregated behaviour of solar photovoltaic power generation and battery energy storage systems on grid exit point load in order to maintain an accurate load forecast

With limited data beyond the grid exit point (GXP) or substation level, how can Transpower determine the effect of the aggregated behaviour of solar photovoltaic power generation and battery energy storage systems on GXP load in order to maintain an accurate load forecast? In this initial study it is assumed that the GXP services a residential region. An algorithm based on non-linear programming, which minimises the financial cost to the consumer, is developed to model consumer behaviour. Input data comprises forecast energy requirements (load), solar irradiance, and pricing. Output includes both the load drawn from the grid and power returned to the grid. The algorithm presented is at the household level. The next step would be to combine the load drawn from the grid and the power returned to the grid from all the households serviced by a GXP, enabling Transpower to make load predictions. Various means of load forecasting are considered including the Holt--Winters methods which perform well for out-of-sample forecasts. Linear regression, which takes into account comparable days, solar radiation, and air temperature, yields even better performance.

Photochemical Phase Transitions Enable Coharvesting of Photon Energy and Ambient Heat for Energetic Molecular Solar Thermal Batteries That Upgrade Thermal Energy.

Discovering physicochemical principles for simultaneous harvesting of multiform energy from the environment will advance current sustainable energy technologies. Here we explore photochemical phase transitions-a photochemistry-thermophysics coupled regime-for coharvesting of solar and thermal energy. In particular, we show that photon energy and ambient heat can be stored together and released on demand as high-temperature heat, enabled by room-temperature photochemical crystal↔liquid transitions of engineered molecular photoswitches. Integrating the two forms of energy in single-component molecular materials is capable of providing energy capacity beyond that of traditional solar or thermal energy storage systems based solely on molecular photoisomerization or phase change, respectively. Significantly, the ambient heat that is harvested during photochemical melting into liquid of the low-melting-point, metastable isomer can be released as high-temperature heat by recrystallization of the high-melting-point, parent isomer. This reveals that photon energy drives the upgrading of thermal energy in such a hybrid energy system. Rationally designed small-molecule azo switches achieve high gravimetric energy densities of 0.3-0.4 MJ/kg with long-term storage stability. Rechargeable solar thermal battery devices are fabricated, which upon light triggering provide gravimetric power density of about 2.7 kW/kg and temperature increases of >20 °C in ambient environment. We further show their use as deicing coatings. Our work demonstrates a new concept of energy utilization-combining solar energy and low-grade heat into higher-grade heat-which unlocks the possibility of developing sustainable energy systems powered by a combination of natural sunlight and ambient heat.

Networked microgrids with roof-top solar PV and battery energy storage to improve distribution grids resilience to natural disasters

Electric power systems are prone to several threats. However, some potential threats e.g., extreme weather or natural disasters, are unavoidable and this can affect socio-economic activities, energy security, and also quality of life. Hence, improving the electric power grid resilience in order to reduce the impact from natural disasters has to be thoroughly studied and understood. This paper presents the challenges and advantages of having sections of a power distribution system constituted by networked microgrids (MGs) to efficiently manage distributed energy resources (DERs), in particular roof-top solar photovoltaic and battery energy storage systems, in order to improve the power distribution system resilience to natural disasters. In this regard, this paper provides a detailed resilience analysis process considering two major case studies, moderate damage and heavy damage, which are tested under different scenarios and levels of disruption, that are evaluated utilizing various resilience metrics. Test results indicate that networked MGs incorporating DERs show the potential to provide support to the power distribution system by scheduling the discharge of battery energy storage systems during outages and improve the resilience of the distribution grid to natural disasters.

Meta-analysis of concrete as a thermal energy storage medium

Solar energy is a renewable energy source however sunlight is only available during limited hours in the day. Researchers are looking towards an efficient energy storage system to ensure constant energy output. Concrete can be used as a filler material in a solar thermal energy storage system. This meta-study compared the heat capacity and thermal conductivity of concrete to other solid materials and concrete aggregates, allowing for the viability of concrete storage systems to be examined. The heat capacity of concrete was 5-10% higher than the comparative solid materials like brick and sand. Additionally, concrete without cement replacement materials were found to be more thermally conductive than concrete with added fly ash, blast furnace slag or silica fume with conductivity decreasing between 81-87%. However, concrete with the supplementary cementitious materials possess a higher heat capacity than concrete without cement replacement with capacity increasing by 25% at 30% replacement by fly ash with a grain size 300-600µm. When compared to the energy efficiency of other thermal energy systems, a concrete thermocline is shown to be less efficient than a molten salt two-tank energy storage system by less than 5%. Therefore, while concrete is a viable solid filler material in thermal energy storage systems, a molten salt two-tank thermal energy storage system is marginally more efficient. However, a partial cement replacement by supplementary cementitious materials can extend the effectiveness of the concrete thermal storage.

Performance Evaluation of Lead Acid Battery -Backup Power System of Solar Hybrid Power Plant

This work is concentrated on determining and evaluating the performance of the lead acid battery energy storage system of the solar hybrid power plant existing at Bahir Dar University. Evaluating the performance of solar battery energy storage system and other integrated units in a stand-alone or grid connected solar power plants having prominent significance and contribution with respect to adapting and utilizing the indispensable solar power (PV) technology in Ethiopia. The battery performance evaluation was done by analyzing the long day performance data of the battery backup unit and by carrying out experimental discharging operation. The battery backup unit performance evaluation was done by analyzing the long day performance, the battery efficiency, charging factor, depth of discharge and capacity of the battery. The results shows that the battery was charged without being discharged a number of times. This can be the result of loss energy by self-discharge of the battery, or wrong setting in recording of input output values or failure of the Xtender inverter charger RCC - 02/03 recording, displaying and control units..

Thermal and hydraulic characteristics of packed bed solar energy storage system having spheres as packing element with pores

Abstract The thermal performance of packed bed storage system can be improved by increasing the heat transfer coefficient between the packing element and heat transfer fluid. The shape of the packing element is one of the factors that influences the heat transfer coefficient. The present experimental investigation is carried out to obtain the influence of spheres having pores as packing element in packed bed storage system. The effects of pore diameter, pore depth, number of pores and mass flow rate is discussed and presented in the present paper. In order to investigate the performance, non-dimensional parameters such as pore to sphere diameter ratio (d/D), pore depth to sphere diameter ratio (t/D), perforation index (PI) and Reynolds number (Re) are considered. The experimentations are carried out for d/D, t/D, PI and Re for the range of 0.066 to 0.20, 0.05 to 0.20, 0.06 to 0.22 and 200 to 800, respectively. The maximum value of thermo-hydraulic parameter is obtained as 0.245 correspond to d/D of 0.20, t/D of 0.06, PI of 0.18 and Re of 800 within the considered range of the investigated parameters. On the basis of the experimental investigation, it is found that the use of sphere with pores as packing element improves the thermal and hydraulic performance of the packed bed storage system.

Experimental investigation of heat transfer and fluid flow behavior of packed bed solar thermal energy storage system having spheres as packing element with pores

Packed bed storage system is one of the viable options of solar thermal energy storage which can be utilized in various applications of wide temperature range. The enhancement in heat transfer coefficient between heat transfer fluid and packing element results in improved thermal performance of it. The heat transfer coefficient is also a function of shape of packing elements. From the literature review, it was found that the solid spheres as packing element comes out with best thermo-hydraulic performance in category of large size packing elements. In this paper, an experimental study has been conducted to investigate the heat transfer and fluid flow characteristics of packed bed solar thermal energy storage system. The outcomes of the experimental investigation are carried out on using large size spherical shaped packing element having pores of various diameters and depths on their surface in packed bed solar thermal energy storage system for low temperature applications. The experimentations are performed for different values of sphere diameter to pore diameter ratio (D/d) from 5 to 15, sphere diameter to pore depth ratio (D/t) from 5 to 20 and Reynolds number from 200 to 800. For the range of parameters investigated, the maximum value of thermo-hydraulic parameter has been obtained as 0.241 correspond to D/d of 5, D/t of 15 and Reynolds number of 800. Based on experimental results it is found that using spheres having pores on the surface as packing elements improve the thermal performance and momentum transport in packed bed solar thermal energy storage system.

Low-energy opportunity for multi-family residences: A review and simulation-based study of a solar borehole thermal energy storage system

The multi-family residential building sector is the least energy efficient in the United States, thus allowing for ample opportunities for significant cost-effective energy and carbon savings. In the present study, we propose a district solar borehole thermal solar energy storage (BTES) system for both retrofit and new construction for a multi-family residence in the Midwestern United States, where the climate is moderately cold with very warm summers. Actual apartment interval power and water demand data was mined and used to estimate unit level hourly space and water heating demands, which was subsequently used to design a cost-optimal BTES system. Using a dynamic simulation model to predict the system performance over a 25-year period, a parametric study was conducted that varied the sizes of the BTES system and the solar collector array. A life-cycle cost analysis concluded that is it possible for an optimally-sized system to achieve an internal rate of return (IRR) of 11%, while reducing apartment-wide energy and carbon consumption by 46%. Both a stand-alone and solar-assisted ground-source heat pump system were designed and simulated for comparison to the BTES system, and found to be less economically favorable than the solar BTES system. Thus, the promise for district-scale adoption of BTES in multi-family residences is established, particularly for new buildings.