Supercapacitor Storage System Research Articles

Power Allocation based on ANN for Hybrid Battery and Supercapacitor Storage System in EV

The paper focuses on presented an ArtificialNeural Network (ANN) approach to allocate power for a hybridenergy storage system (HESS) in an Electric Vehicle (EV). TheHESS is comprised of a battery and supercapacitor, and theANN algorithm aims to optimize power allocation between thesetwo energy storage devices. The data for ANN training wasbased on cost optimization-based power allocation fromprevious research. While optimization can often take highcomputational resource and time, it is expected that a welltrained ANN can allocate power for the EV HESS more quickly.In this research, the inputs to the ANN are the required powerderived from the drive cycle, energy and power capacity of thebattery and supercapacitor, and state of charge (SoC) of thebattery and supercapacitor. The trained ANN was trained withvarious inputs not used in the training and it shows satisfactoryperformance.

“Adaptive virtual synchronous generator control using optimized bang-bang for Islanded microgrid stability improvement”

In this paper, a virtual synchronous generator (VSG) controller is applied to a hybrid energy storage system (HESS) containing a battery energy storage system and supercapacitor storage system for maintaining the frequency stability of an isolated microgrid. The microgrid contains a photovoltaic generation system and a diesel generator in addition to the HESS and two constant impedance loads that are fed through a medium voltage radial feeding system. The adaptive virtual inertia constant (H) with constant virtual damping coefficient (D) based on ‘ bang-bang’ control for the microgrid’s frequency stability enhancement is investigated and compared with the constant parameter VSG. In addition, the bang-bang control is modified to adapt the D beside the adaptive H, and the system response is investigated and compared with the conventional adaptive H technique. The VSG parameters are evaluated based on two different methods. The first is a computational method based on the simplified small signal stability analysis, while the other is based on an optimization method using two different objective functions and the particle swarm optimization technique. This paper also investigates the superiority of the proposed technique compared to other techniques in enhancing frequency stability, accelerating steady-state frequency restoration, and reducing the energy requirement of the HESS. The required power from the HESS is shared between the two energy storages using the low pass filter technique so as to reduce battery peak current.

A Novel Fuzzy-Logic-Based Control Strategy for Power Smoothing in High-Wind Penetrated Power Systems and Its Validation in a Microgrid Lab

Wind power generation has undergone significant development in recent decades due to its environmental advantages and its economic competitiveness. However, its increasing level of penetration is not exempt from drawbacks, such as those derived from the fluctuating nature of the wind. To reduce its negative incidence on grid power quality and stability, different techniques have been developed, such as those based on power smoothing. In these techniques, there is a research gap on the adjustment of the time constant that adapts to the needs of the smoothing, avoiding uncertain results, computational efforts and delays in the response of the control. This paper addresses the problem, proposing a novel method for power smoothing in a wind turbine by using a fuzzy-logic-based supercapacitor storage system and time-constant fitting, with a first-order adaptive transfer function. The method considers as input variables the active power generated by the wind turbine and the state of charge of the supercapacitor, both sampled simultaneously. After a computation process, the proposal generates active power set-point values that the supercapacitor must produce to compensate for the intermittency of the wind, seen from the point of connection to the grid. The results were validated experimentally with comprehensive laboratory tests.

Relating the Electrochemical Behavior of Birnessite to the Morphology and Specific Surface: Interest of Studying the Surface Reactivity

This article focuses on understanding the link between the morphologies and specific surfaces of well-known birnessites with electrochemical performance by studying the surface reactivity of each material. Our study is especially dedicated to show the impact of the material’s surface on the faradaic and pseudocapacitive mechanisms involved in the energy storage of the supercapacitors. For this purpose, a multiscale study was carried out on three birnessites, nonprotonated (Na-MnO2, K-MnO2 and HT-MnO2) and protonated (HNa-MnO2, HK-MnO2 and HHT-MnO2), to ensure the investigation of the surface reactivity on birnessites for each step of the nanocomposite conception based on birnessite. Scanning electron microscopy (SEM) was used to characterize the morphology of the materials. Coupling X-ray photoemission spectroscopy (XPS) and SO2 gas probe adsorption are especially devoted to determine the nature of active sites and the electronic structure of the material’s surface. Thus, we provide evidence that the surface properties, such as specific surface area and surface active sites, are linked to the electrochemical mechanism (faradaic or pseudocapacitive) of storage depending on the scan rate. We show that the site concentration determined by XPS can be directly linked to the contribution of the pseudocapacitive mechanism observed at low and moderate scan rates. As the capacitive mechanism is discriminated at a high scan rate, its contribution is related to the Brunauer–Emmett–Teller (BET) surface. The largest specific surface is obtained for HK-MnO2 with its eroded veils (85 m2/g). Redox reactivity was evaluated from XPS quantification comparing the S/M values, i.e., atom % of S/atom % of Mn. HT-MnO2, its protonated derivative HHT-MnO2, and Na-MnO2 exhibit the largest redox reactivity, with, respectively, S/M values of 0.49, 0.46, and 0.31, according to their smooth platelet morphology. Except for the high temperature birnessite, the change of morphology after protonation decreases the concentration of redox active sites while the BET surface increases. This work shows that HK-MnO2 presents the best performance, 46.6 F/g at 100 mV/s, to be used as an electrode material in supercapacitor storage systems.

Model predictive control of solar photovoltaic‐based microgrid with composite energy storage

SummaryThe renewable energy (e.g., solar photovoltaic)‐based grid‐connected microgrid (MG) with composite energy storage system (CESS) is feasible to ensure sustainable and quality power to the commercial and domestic load demands. Effective control systems provide the dynamic performance of such deployed MGs. This paper investigates the application of the finite control‐set model predictive controller (FCS‐MPC) for solar photovoltaic‐based grid‐connected MGs with composite energy storage. FCS‐MPC considers the discrete nature of interfacing (DC–AC and DC–DC) converters into the control algorithm to predict the optimal control command for reference current tracking. Compared to classical control approaches, FCS‐MPC provides a fast‐dynamic response, discards the modulation stage, and effectively handles the effects of dynamic source and load variations and nonlinear loads. The control system encapsulates a proportional–integral (PI) controller, low‐pass filter (LPF), power management algorithm (PMA) unit, and followed by the FCS‐MPC approach. The CESS unit consists of a battery and supercapacitor storage system. The efficacy of the FCS‐MPC approach is verified through the MATLAB/Simulink results. Solar photovoltaic variation due to irradiance, utility grid availability, electricity pricing, and dynamic load variations are considered in the implementation. Furthermore, real‐time simulation of the proposed method is validated using OPAL‐RT OP4510 real‐time simulator.

Topology, Analysis, and Modeling of Voltage Equalizers Based on Reutilization Technique for Supercapacitor Storage System

The voltage equalizers based on the switched capacitor are widely used in energy storage system because of its simple circuit structure and easy realization. However, the voltage stress and the number of bypass capacitors in traditional switched-capacitor equalizers are enormous due to the large number of energy storage cells, and they can only realize balance of a single string. Therefore, three improved switched-capacitor equalizers based on reutilization technique are proposed to solve the problems. The supercapacitors in the circuit can be used as energy storage cells and energy transfer cells through the reutilization of energy, thus avoiding the extensive use of bypass capacitors and achieving the balance between strings. Meanwhile, the design difficulty of equivalent equalization resistance and the switch number are greatly reduced. The circuit configuration, operation principle, and modeling are illustrated in detail. Finally, three experiment prototypes are established. The results verify the feasibility of the proposed topologies.

Improving the Transient Response of Hybrid Energy Storage System for Voltage Stability in DC Microgrids Using an Autonomous Control Strategy

In renewable microgrid systems, energy storage system (ESS) plays an important role, as an energy buffer, to stabilize the system by compensating the demand-generation mismatch. Battery energy storage system serves as a decisive and critical component. However, due to low power density and consequently slow dynamic response the lifetime of BESS is observably reduced due to high current stress, specifically experienced during abrupt/transient power variations. Hence, hybridization with supercapacitor storage system is conferred. Additionally, the controllers designed for energy storage systems should substantially respond for compensating the transient requirement of the system. In this article, we propose a decoupled control strategy for batteries and supercapacitors based on k - Type compensators and a nonlinear PI controller (NPIC) respectively. The formulated control design is tested for voltage regulation in a standalone microgrid. Furthermore, a comparative analysis is presented with benchmark low-pass-filter (LPF) based controller. The results obtained shows the proposed control technique possess a faster response with improved voltage regulation capabilities. For the test system regulated at 48 V for various abrupt load-generation various case studies presented, the proposed methodology maintains a significantly reduced voltage deviation between 47 V - 51 V in contrast to 45 V - 56 V observed in the LPF methodology. Furthermore, the complexity is simpler in comparison to LPF based control strategy and a comparative obviation of additional sensing devices is achieved, that inherently reduces the detrimental effect on ESS response during transient condition.

Design and testing of a supercapacitor storage system for the flash recharge of electric buses

This paper proposes a hybrid storage for urban transport systems in order to reduce recharge time and increase its life and reliability. Proposed system is applied to a pre-existing electric vehicle, introducing through proposed revamping procedure a methodology for a fast integration of proposed systems on different vehicles. Finally, the system is calibrated and tested showing how the proposed control layout really simplifies the vehicle commissioning.

Design and testing of a supercapacitor storage system for the flash recharge of electric buses

This paper proposes a hybrid storage for urban transport systems in order to reduce recharge time and increase its life and reliability. Proposed system is applied to a pre-existing electric vehicle, introducing through proposed revamping procedure a methodology for a fast integration of proposed systems on different vehicles. Finally, the system is calibrated and tested showing how the proposed control layout really simplifies the vehicle commissioning.

Hybrid four‐level FC inverter using an internal supercapacitor storage system for a microgrid connected application

In this study, a new topology of grid-connected four-level inverter is introduced. The proposed structure, based on intermediate supercapacitors energy storage, is introduced to ensure two operation modes: to provide power to a microgrid from renewable energy sources and to regulate its voltage during short-term power disturbances. The main idea is to replace ordinary capacitors of a four-level flying capacitor (FC) inverter by supercapacitors and operate them under variable voltage conditions. The control strategy applies linear matrix inequalities approach as well as space vector modulation technique to generate the appropriate switching states. The latter part of this study is dedicated to the redundant state selection method for supercapacitors voltages balancing. Through experimental implementation, presented results highlight the efficiency of the proposed hybrid inverter in ensuring microgrid stability.

Integrated standalone hybrid solar PV, fuel cell and diesel generator power system for battery or supercapacitor storage systems in Khorfakkan, United Arab Emirates

Renewable energy resources play a very important rule these days to assist the conventional energy systems for doing its function in the UAE due to high greenhouse gas (GHG) emissions and energy demand. In this paper, the analysis and performance of integrated standalone hybrid solar PV, fuel cell and diesel generator power system with battery energy storage system (BESS) or supercapacitor energy storage system (SCESS) in Khorfakkan city, Sharjah were presented. HOMER Pro software was used to model and simulate the hybrid energy system (HES) based on the daily energy consumption for Khorfakkan city. The simulation results show that using SCESS as an energy storage system will help the performance of HES based on the Levelized cost of energy (LCOE) and greenhouse gas (GHG) emissions. The HES with SCESS has renewable fraction (68.1%) and 0.346 $/kWh LCOE. The HES meets the annual AC primary load of the city (13.6 GWh) with negligible electricity excess and with an unmet electrical load of 1.38%. The reduction in GHG emissions for HES with SCESS was 83.2%, equivalent to saving 814,428 gallons of diesel.

An innovative approach of optimizing size and cost of hybrid energy storage system with state of charge regulation for stand-alone direct current microgrids

• This paper proposed a mathematical model for multi-objective optimization of hybrid energy storage system (HESS) in detail. • A novel penalty cost function for the HESS and a new SOC regulation concept for supercapacitor storage system have been introduced. • The proposed model was analysed under a case study. • An optimal HESS sizing was achieved to obtain the minimum total investment cost of HESS including the future replacement costs. • The best value for the energy ratio between supercapacitor storage and battery storage for the considered load profile was found as 25%. This study proposed a novel approach to optimize size and cost of hybrid energy storage systems (HESS) based on a solar photovoltaic (PV) fed stand-alone DC microgrid, while considering the state of charge (SOC) of both batteries and supercapacitors to assure the long life of batteries and well-being during the operation. The sizing strategy is combined with an optimization model and a HESS Assessment Algorithm. The strategy differs from traditional strategies since it comprises of not only the system cost, but also SOC regulation of both batteries and supercapacitors. A unique penalty cost function depending on the unutilized solar power generation and unserved demand power after HESS is fully charged or discharged has been introduced. By this penalty cost function, SOC of HESS can be kept within a safer margin to guarantee the system stability. Also, system availability can be assured by penalizing the unserved demand power. A new SOC regulation concept for supercapacitors has been introduced. SOC of supercapacitors is maintained in between a predefined focused band to ensure the supercapacitors availability to absorb or deliver sudden power fluctuations. The lifetime of HESS and the solar PV system are considered in the objective function to find the optimum sizing of HESS. The simulation was performed under Hambantota Solar Park weather conditions using MATLAB. Multi-objective genetic algorithm is used to optimize the objective functions. Comparing with a traditional sizing method, it shows that the novel optimal sizing strategy can reduce the BS system capacity by 18% by the hybridization of supercapacitors. The best value for the energy ratio between supercapacitors and batteries, for the considered load profile was found to be 25%. Results prove that the number of penalties, surplus solar power generations and unserved demand power were made minimum while obtaining an optimal sizing of HESS with a minimum system investment cost.

Energy management and control strategy for a DFIG wind turbine/fuel cell hybrid system with super capacitor storage system

This paper deals with a modeling and control of a hybrid power system based on fuel cell and wind turbine (WT) system based a Doubly Fed Induction Generator (DFIG). To improve the performance of the hybrid energy system, a super-capacitor storage system is associated with a fuel cell which is not able to compensate the fast variation of the load power demand. In this case, rule based energy management algorithm should be applied to share energy between three source elements in order to satisfy load power demand. The main originality of this work lies in the new topology of the WT-DFIG/Full cell/super capacitor hybrid power system which presents an easier accessibility of DC and AC grid. For the wind energy conversion system, the proposed control is the Maximum Power Point Tracking algorithm based a torque control loop (OTC). The wind turbine is equipped with a DFIG operated at variable speed which the control is based on direct power control. Simulation results show the effectiveness of the proposed control strategy and the energy management algorithm. A dSpace 1104 real-time board is used for management algorithm implementation. The obtained experimental results prove the efficiency of the proposed control strategy.

Extending the Autonomy of a Battery for Electric Motorcycles

Electric motorcycles use a battery storage system and a controlled inverter (motor drive) to drive the wheels. Given that the sale of electric motorcycles is expected to grow significantly over the next decade, the aim of this research is to add a supercapacitor storage system to this simple network in order to extend the autonomy of the motorcycle. This paper analyzes and demonstrates the benefits of two different structures for adding a supercapacitor bank to a lithium-ion battery pack: a passive filter and a buffer for the battery. The advantages of each structure are presented and design guidelines are provided. In addition, we propose a synthetic inductor filter typology based on the two analyzed structures in order to increase the autonomy of the motorcycle. Simulations and experimental results using real data validate the analysis. This paper then uses real data extracted from an electric motorcycle to compare the four topologies: batteries only, the passive filter, the buffer, and the synthetic inductor semi-active hybrid storage system. The comparison shows that battery capacity is extended up to 7.8% with a smoother current profile. However, due to the losses from the added converter in cascade, the net capacity of the whole system is extended only up to 3.7%. Therefore, improvements in the dc/dc converter can further increase the entire system capacity.

Self-Excited Induction Generator Based Microgrid with Supercapacitor Energy Storage to Support the Start-up of Dynamic Loads

A supercapacitor storage system (SCSS) is used for improving the dynamic performances of a microgrid (MG) fed by a self-excited induction generator (SEIG), in the case of the direct ...

Electromagnetic processes of charging of on-board supercapacitor storage system during the regenerative braking mode of DC electric rolling stock with series-wound DC motors

The paper is dedicated to the task of improving of regenerative braking of a DC train with the series-wound DC traction motors. It is proposed the schematic solution for the trains with DC motors, which is based on the storing of recovered energy by the on-board supercapacitor storage system and extending the speed range of regenerative braking. The scheme is described by expressions which allowed to build the time dependences of main values. In addition, the experimental researches with the multiple-unit train were performed to find initial data for calculations and verification the results. The transient processes of charging are analyses for different cases of storage capacitances, residual voltages and initial speed of braking. It was proved, that the scheme allows to increase the value of recovered energy up to 40%, but its value strongly depends on the initial conditions and parameters of the system.

Optimal Operation for Supercapacitor Storage System Using Piecewise LQR Voltage Equalization Control

A closed-loop piecewise linear quadratic regulation (PLQR) voltage equalization controller is proposed for a supercapacitor storage system to optimize supercapacitor operation in terms of voltage differences among supercapacitor cells with the desired voltage tracking. In this study, under constant current charging mode, a model system is built based on the switched-capacitor method. The state equation of the errortracking system is derived. By adopting an idea derived from Lyapunov elliptic domains, the PLQR algorithm is proposed to change the feedback gain dynamically to satisfy the control input constraints. Simulation results verify the effectiveness and feasibility of the proposed algorithm.

Design and Analysis of Novel Control Strategy for Battery and Supercapacitor Storage System

In this paper, a simple novel control strategy is designed and analyzed for a hybrid energy storage system (HESS). In the proposed method, batteries are used to balance the slow changing power surges, whereas supercapacitors (SC) are used to balance the fast changing power surges. The main advantage of the proposed control strategy is that, the slow response of battery system including dynamics of battery, controller, and converter operation, is overcome by diverting the power surges to the SC system. The proposed method inherits charge/discharge rate control to improve the life span and reduce the current stresses on battery. The proposed method features less computational burden as it uses simple control strategy. The detailed experimental results presented validate the proposed control strategy for sudden changes in photovoltaic (PV) generation and load demand.

The Energetic Macroscopic Representation Modeling of Super Capacitor Storage System and Capacity Configuration Research

Super capacitor bank operating characteristics have an important impact on the energy conversion efficiency and the construction cost of the hybrid energy storage system. To research the parameters and control properties of super capacitor in energy storage system, to establish a practical mathematical model and to propose the optimal design is important to improve the overall performance of the hybrid energy storage system. This paper presents the mathematical modeling of battery super capacitor hybrid energy storage system, studies the target parameters setting of hybrid energy storage system and the capacity configurations of super capacitor, and proposes an optimized design of the super capacitor bank. Finally, based on EMR verifies the theory.

A statistical model to determine the capacity of battery–supercapacitor hybrid energy storage system in autonomous microgrid

Battery–supercapacitor hybrid energy storage system (BSHS) is a key component for regulating the frequency in autonomous microgrid. The lifetime and capacity are two important aspects for the efficient and economic use of BSHS. In this paper, the above two aspects are investigated in detail. Firstly, a new frequency control strategy based on hysteretic loop is developed for BSHS to extend the battery lifetime by avoiding small charge/discharge cycles. Then a capacity statistical model which is composed of statistical analysis, time-domain simulation and a capacity determination algorithm is proposed. Monte Carlo simulation is implemented to the statistical model to obtain the capacity distributions of BSHS. Finally, a benchmark low voltage microgrid is established as the test system using the commercial software DIgSILENT. Simulation results verify the effectiveness of the hysteretic loop control strategy and the capacity statistical model. The obtained capacity distributions of BSHS are used to determine the optimum capacity according to the needs of operation. The results also show that the hysteretic loop control strategy can reduce the capacity of Battery Energy Storage System (BESS) while increase the capacity of Supercapacitor Storage System (SCSS).