Supercapacitor Energy Storage System Research Articles

Biosynthesis of zinc oxide-cobalt oxide nanocomposite as electrode material and its performance evaluation for the sustainable hybrid supercapacitor energy storage devices

Novel energy storage techniques and systems have gained increasing importance in recent times to overcome the variability in the output of non-dispatchable renewable energy sources. Supercapacitors are energy storage systems that have attracted considerable attention from various stakeholders. However, the performance of an effective supercapacitor energy storage system depends mainly on the electrochemical behavior of the electrodes, and the methods used to fabricate the electrode materials. Sustainable methods for the fabrication of electrode materials such as green synthesis have recently attracted researchers. In this work, a method is proposed to synthesize zinc oxide and cobalt oxide nanocomposite using green synthesis to take advantage of their superior electrochemical properties and stability. Evaluation of the morphological and electrochemical performance of the fabricated nanocomposite showed good results. Further, the electrode material fabricated using the synthesized nanocomposite has shown energy density values in the range of 3.8 Wh/kg to 9.54 Wh/kg for the power density values of the range 3000 W/kg to 375.3 W/kg for the different chosen current densities. A retention capacity of approximately 85% was observed even after 5000 cycles which is one of the most important features of supercapacitors. Thus, green synthesis with its intrinsic advantages over chemical methods is expected to be a promising approach for the fabrication of electrode materials for supercapacitors in sustainable energy storage applications in the future.

An adaptive energy management strategy for supercapacitor supported solar-powered electric vehicle charging station

Abstract Large-scale electric vehicle integration into the grid is expected in the imminent future. Congestion caused by these integrations can be addressed through a hybrid AC/DC microgrid. The DC sub-grid is exclusively dedicated to incorporating electric vehicles. Solar-powered charging station supported with a supercapacitor energy storage system in the DC sub-grid reduces the stress on the AC sub-grid. This paper presents a hybrid AC/DC microgrid voltage/frequency stability improvement strategy based on adaptive DC-link voltage regulation assisted by energy storage. The proposed volatility-based approach is an efficient strategy to enhance the microgrid stability during generation intermittency and load fluctuations. The combined control scheme of the interlinking converter and supercapacitor energy storage in the independent and hybrid operation modes achieve energy balance with the variations in solar irradiation and the addition/disconnection of electric vehicles. The proposed energy management strategy is tested in real-time under various volatile conditions to validate the performance. The hybrid microgrid with proposed energy management strategy provided a frequency improvement of 0.55% and voltage improvement of 5.4%.

Improvement of Low-Voltage Ride-Through Capability for Wave Energy Conversion System

With the wave energy conversion system (WECS) integrated to grid, the lack of satisfactory ability to ride through transient voltage faults will reduce the stability and reliability of the grid. In this article, in order to enhance the low-voltage ride-through (LVRT) capability of the WECS, the structure and the mathematical model of a magnetic-gear permanent magnet synchronous generator (MG_PMSG) and a float-type wave energy converter are introduced first. The output power characteristic of the WECS is analyzed. Then, a novel coordinative LVRT control scheme based on supercapacitor energy storage system (SC_ESS) is proposed. The control scheme includes four modes, which are determined by the severity of voltage sags and active power deviation of the WECS. Machine-side converter control, grid-side converter, control and SC_ESS control are used coordinately in the four operation modes. The results of simulation and experiment have verified the effectiveness of the proposed control scheme in normal running conditions.

Enhancing energy management of a stationary energy storage system in a DC electric railway using fuzzy logic control

In DC electric railways, energy storage systems (ESSs) have been addressed to assist in the energy efficiency improvement, which is achieved by exploiting the captured excess braking energy of decelerating trains in order to reduce the traction energy demand of the accelerating trains. Conventionally, stationary ESSs are assumed to have access to the substations and grid, which is being a significant shortcoming since the ESS in many locations such as the London Underground has neither access to the traction substations nor external sources. Since ESSs cannot have infinite capacity and have practical restrictions on the state of charge (SOC), much of the regenerative energies during braking are being lost, which reduces the benefits of ESSs in enhancing energy efficiency of electric railways. In this paper, boosting the energy efficiency of the system is achieved by proposing a new adaptive control method based on fuzzy logic control (FLC) to dynamically control a stationary ESS connected to a DC track system. Therefore, the power flow between the track and the ESS with respect to the storage capacity is managed without affecting the benefits yielded by the system. The proposed control method is simulated and tested experimentally on a real prototype including a supercapacitor ESS. Three traffic scenarios are applied to evaluate the feasibility and the performance of the proposed controller with respect to the undefined traffic scenarios matching the case in the London Underground. The proposed control method applied to three traffic scenarios have achieved energy savings of 39.2–41.4%. The experimental results are compared against the simulation results, showing a percentage error ranging from 1.8 to 3.6%.© 2017 Elsevier Inc. All rights reserved.

Comprehensive Control Strategy Considering Hybrid Energy Storage for Primary Frequency Modulation

The increase in the number of new energy sources connected to the grid has made it difficult for power systems to regulate frequencies. Although battery energy storage can alleviate this problem, battery cycle lives are short, so hybrid energy storage is introduced to assist grid frequency modulation. In this paper, a hybrid energy storage system composed of battery energy storage and super-capacitor energy storage systems was studied, and a comprehensive control strategy was proposed. Firstly, by setting the frequency dead zone of the energy storage to be smaller than that of the thermal power unit, the frequent action of the thermal power unit was avoided. Secondly, virtual inertial control and virtual droop control were effectively combined. Then, the state of charge of battery energy storage and super-capacitor energy storage was considered so that they could operate in harmony. Finally, a simulation model was built in MATLAB/SIMULINK, and case studies were conducted to verify the proposed control strategy. Results showed that the proposed control strategy could effectively reduce the frequency deviation of the power grid, and maintain the state of charge, reduce the number of operated batteries, and improve cycle life.

A multi-objective control scheme of a voltage source converter with battery–supercapacitor energy storage system used for power quality improvement

Conventionally, an energy storage system and two Voltage Source Converters (VSCs) are required to combine the operation of Distribution Static Compensator (DSTATCOM) and Uninterruptible Power Supply (UPS). The DSTATCOM’s VSC can compensate for the source voltage sag and swell. However, it cannot compensate for the voltage interruption. On the other hand, the VSC of the UPS can compensate for the source voltage interruption, but it cannot compensate for the voltage sag and swell. This paper proposes a control algorithm that uses a single VSC and a battery–supercapacitor energy storage system to function as DSTATCOM and UPS. The VSC and the battery–supercapacitor energy storage system mitigates the sag, swell, and interruption of the source voltages. Under the normal source voltages, this system mitigates the load current harmonics, unbalance, and reactive power. The proposed control algorithm uses a State of Charge (SoC) based scheme to control the battery–supercapacitor energy storage system. This control scheme protects the battery and supercapacitors from overcharging. Also, it eliminates the ripples in the load angle and increases the battery cycle life. The efficacy of the proposed control scheme has been verified through the experimental setup of the VSC with the battery–supercapacitor energy storage system in the laboratory.

A fast adaptive bus voltage regulation strategy for supercapacitor energy storage systems

Supercapacitors undergo wide terminal voltage fluctuations, which makes it difficult to maintain a stable bus voltage and develop a satisfactory dynamic response. To solve this problem, a fast adaptive bus voltage regulation strategy is proposed in this paper. Firstly, the dual-loop controller with an external voltage loop and an internal current loop is applied to the supercapacitor energy storage systems. Secondly, an adaptive proportional–integral controller is designed for the outer voltage loop to accommodate the variations of the system characteristics. Furthermore, in order to improve the dynamic response, the set-point automatic modulation is integrated into the voltage control loop to compensate the stochastic load demanded fluctuations. The simulation and experimental results show that the proposed method ensures the stability of the bus voltage and provides a lower fluctuation and shorter settling time compared with the conventional method.

Super-capacitor energy storage system to recuperate regenerative braking energy in elevator operation of high buildings

<span>In operating phases of elevators, accelerating, braking modes occur frequently, so braking energy recuperation of elevators has contributed considerably to decrease the total electric energy consumption for operating elevators in multi-floor buildings. In this paper, the supercapacitor energy storage system is used to recover regenerative braking energy of elevators when they operate down full-load and up no-load, reducing fluctuation of voltage on DC bus as well. Therefore, super-capacitor energy storage system (SCESS) will be parallel with line utility to recuperate regenerative braking energy in braking phase and support energy for acceleration phase. The surplus energy will be stored in the supercapacitors thanks to a DC-DC converter capable of exchanging energy bidirectionally in buck/boost modes, and designing control strategy including two control loops. Inner loop-current loop: controlling charge/discharge process of supercapacitors by current iL complying with operation characteristic of elevator; Outer loop-voltage loop: managing UDC-link at a fixed value. Simulation results with elevator system of the ten-floor building, Hanoi, Vietnam installed SCESS have been verified on MATLAB Simulink, SimPowerSystem with saving energy level about 30%.</span>

Review of Peak Shaving Features of the Power Box

In this review article, a considerable discussion and details on peak shaving strategies involving incorporation of the electric vehicles to the grid, integration of energy storage system, demand‐side management, and renewable energy sources have been presented. Three types of peak shaving using energy storage systems, such as the battery energy storage system, supercapacitor energy storage system, and flywheel energy storage system, have been explained with the advantages and disadvantages of the different approaches. In one of these studies, the integration of a renewable photovoltaic source with battery energy storage in peak shaving has successfully produced an annual savings of $155 675.00. The introduction to the cost–benefit and sustainable second‐life batteries energy storage and their relationship with electric vehicles is also described. Another study involving electric vehicles BYD e6, which have the cheapest energy storage cost of 0.1208 $ kWh−1 and participated the most in peak shaving, obtains the most significant individual net income compared to other vehicles. Different demand‐side management practices and their advantages are thoroughly discussed. Finally, this article also includes the challenges, importance, perspectives, future work suggestions, and improvements on peak shaving performance, such as implying the smart grid energy storage technology to achieve the Sustainable Development Goal 7.

A nonlinear double‐integral sliding mode controller design for hybrid energy storage systems and solar photovoltaic units to enhance the power management in DC microgrids

In this paper, a nonlinear decentralized double-integral sliding mode controller (DI-SMC) is designed along with an energy management system (EMS) for the DC microgrid (DCMG). This DCMG includes having a hybrid energy storage system (HESS) that incorporates a battery energy storage system (BESS) and supercapacitor energy storage system (SCESS) while the load demand is met through the power generated from solar photovoltaic (SPV) units. First, dynamical models of each subsystem of DCMGs such as the SPV system, BESS, and SCESS are developed to capture highly nonlinear behaviors of DCMGs under various operating conditions. The proposed nonlinear DI-SMC is then designed for each power unit in DCMGs to ensure the desired voltage level at the common DC-bus and appropriate power dispatch of different components to fulfill the load requirement of the DCMG. On the other hand, an energy management system (EMS) is designed to determine the set point for the controller with an aim of ensuring the power balance within DCMGs under various operating conditions where the overall stability is assessed using the Lyapunov theory. Simulation studies along with the processor-in-loop validation, including a comparative study with a proportional-integral (PI) controller, verify the applicability and effectiveness of the EMS-based DI-SMC under different operating conditions of the DCMG.

Optimal supercapacitor placement in an urban railway line

Supercapacitors (SCs) are important devices used in renewable energy storage applications on urban railways due to their high power density, good performance, and long maintenance-free lifetime. The position and capacity of supercapacitors play an essential role in increasing energy efficiency and improving the operating condition of the power supply system. This paper proposes an optimal methodology to place a supercapacitor energy storage system (SESS) for urban railway lines. The proposed method uses simulation tools to determine the level of renewable energy as well as the cycle of renewable energy occurrence at substations. Next, based on the working characteristics of the supercapacitor to calculate the accumulated energy that can be reused. Finally, the problem of the optimal siting and sizing of the SESSs is solved to maximize the economic benefits. A case study is applied to evaluate the algorithm. The simulation results demonstrate that installing the optimal SESS can increase energy efficiency, lower transient power, and the solution found is the best choice for economic goals

Bidirectional Power Control Strategy for Super Capacitor Energy Storage System Based on MMC DC-DC Converter

In order to equip more high-energy pulse loads and improve power supply reliability, the vessel integrated power system (IPS) shows an increasing demand for high-voltage and large-capacity energy storage systems. Based on this background, this paper focuses on a super capacitor energy storage system based on a cascaded DC-DC converter composed of modular multilevel converter (MMC) and dual active bridges (DAB). The cascaded converter is called MMC-DAB for short. This paper analyzes the topology and modulation strategy of the system in detail. Taking into account the shortcomings of the traditional bidirectional power control strategy, this paper proposes a control strategy where the DAB module of each branch independently controls the voltage of the sub-module capacitor. The mathematical models of the traditional and the proposed control strategy are established. The stability of the two control strategies is analyzed and compared. Finally, a MW-level engineering prototype of the MMC-DAB energy storage system is designed and manufactured, and the effectiveness of the proposed control strategy was verified through experiments.

Adaptive Sliding Mode Control Method for Onboard Supercapacitors System

Urban rail trains have undergone rapid development in recent years due to their punctuality, high capacity and energy efficiency. Urban trains require frequent start/stop operations and are, therefore, prone to high energy losses. As trains have high inertia, the energy that can be recovered from braking comes in short bursts of high power. To effectively recover such braking energy, an onboard supercapacitor system based on a radial basis function neural network-based sliding mode control system is proposed, which provides robust adaptive performance. The supercapacitor energy storage system is connected to a bidirectional DC/DC converter to provide traction energy or absorb regenerative braking energy. In the Boost and Buck modes, the state-space averaging method is used to establish a model and perform exact linearization. An adaptive sliding mode controller is designed, and simulation results show that it can effectively solve the problems of low energy utilization and large voltage fluctuations in urban rail electricity grids, and maximise the recovery and utilization of regenerative braking energy.

A Coordination Control between Battery and Supercapacitor Energy Storage Systems to Segregate Power for On-Grid Application

Abstract The present work describes a control methodology for a hybrid energy storage system (HESS) to improve its transient performance under dynamic load conditions. The proposed coordination control enhanced life cycle performance by segregating the power between battery energy storage systems (BESS) and a supercapacitor (SC). The BESS and SC are connected parallel to each other, and two individual DC–DC bidirectional converters connect them to a common DC bus. The coordination control is established between the controllers of BESS and the SC of HESS, which helps to utilise the usable energy capacity of the HESS. The charging/discharging current of the BESS is controlled within the allowable safety range based on the slope and magnitude of the BESS current. The high-frequency power component is handled by the SC, which helps to reduce the extra exhaustion on the BESS during operation with a higher current. The proposed coordination control of HESS is validated through simulation and the results show the effectiveness of the proposed controller.

Research on super-capacitor fast power control system

In the context of carbon peak and carbon neutrality targets, high-proportion new energy power systems exhibit low inertia and weak damping characteristics. The frequency stability of the new power system has become a major problem for the safe and stable operation of the power grid. The traditional primary frequency modulation technology based on thermal power units or hydropower units has the defects of slow response speed and long frequency detection delay time. Therefore, we propose a multi-functional multiplexing super capacitor fast power control system, which has the functions of frequency stability control and voltage sag management. In the meantime, we proposed a fast frequency detection algorithm for cascaded signal delay, and the frequency detection delay is less than 10 ms. The system uses a high-speed communication ring network, and the communication delay is less than two milliseconds. Finally, we built a super capacitor energy storage system with a capacity of 50kW to verify that the super-capacitor has the ability to quickly and actively support the power system under frequency disturbances.

Development of a Smart Supercapacitor Energy Storage System for Aircraft Electric Power Systems

This paper presents the development of a supercapacitor energy storage system (ESS) aimed to minimize weight, which is very important for aerospace applications, whilst integrating smart functionalities like voltage monitoring, equalization, and overvoltage protection for the cells. The methodology for selecting the supercapacitor cells type/size is detailed to achieve the safest and most energy-dense ESS. Additionally, the development of the interface electronics for cells’ voltage monitoring and overvoltage protection is presented. The proposed design implements a modular distributed architecture coordinated using communication buses to minimize the wirings and associated complexity and to enable system reconfiguration and expansions, as well as fault diagnoses. Validating the proposed ESS functionalities has been done via experimental testing and the results are presented and discussed.

Fault Ride Through Capability Enhancement of Permanent Magnet Synchronous Generator-based Wind Energy Conversion System

With the speedy increase of wind energy in electric networks, many important issues could emerge, where the most important matter is to maintain the connection of wind generators during fault conditions. With different faults in the electrical network, the voltage at the point of common coupling (PCC) decreases causing unwanted transients in the stator currents. This results in substantially increased fluctuations in the DC-link voltage (Vdc). To avoid this negative impact, it is a must to maintain the capability of wind generators to continue linked to the network during faults, which is depicted as low voltage ride through (LVRT) capability. This paper investigates the LVRT enhancement by two techniques, the first is based on Braking Chopper (BC) and the second method is based on electrical double-layer capacitors (EDLC), or Supercapacitor Energy Storage System (SCESS), under abnormal conditions. The full model of the permanent magnet synchronous generator (PMSG) system and FRT technique are performed in MATLAB/Simulink platform. As a consequence of the findings, both the BC and SCESS are capable to provide satisfactory performance with superior FRT capability for the SCESS compared to the BC.

Improved direct model predictive control for variable magnitude variable frequency wave energy converter connected to constant power load

Archimedes wave swing (AWS) is the first direct-drive wave energy converter (WEC). The AWS is coupled to a linear permanent magnet synchronous generator (LPMSG) and generates a variable magnitude, variable frequency voltage. This paper presents an improved version of direct model predictive control (DMPC) which called improved DMPC (I-DMPC) for a hybrid system containing WEC, supercapacitor (SC) energy storage system (ESS), and constant power load (CPL). This method is implemented based on discrete incremental model of generator and modified objective function, therefor steady-state error is reduced. Simulation results in the MATLAB/SIMULINK environment show the proposed control can maintain stability of the system under different CPL demand and systems faults and improve robustness and fault-tolerant capability of the system in regular and irregular waves. The Comparing results with the conventional DMPC indicate, that by using I-DMPC, d-axis and q-axis errors under regular wave can be reduced 37.5% and 50%, respectively. Also, under irregular wave, I-DMPC reduce the peak of q-axis errors from 73A to 1.5 A when loss of one leg occurred.

Energy Management System for Hybrid PV/Wind/Battery/Fuel Cell in Microgrid-Based Hydrogen and Economical Hybrid Battery/Super Capacitor Energy Storage

The present work addresses the modelling, control, and simulation of a microgrid integrated wind power system with Doubly Fed Induction Generator (DFIG) using a hybrid energy storage system. In order to improve the quality of the waveforms (voltages and currents) supplied to the grid, instead of a two level-inverter, the rotor of the DFIG is supplied using a three-level inverter. A new adaptive algorithm based on combined Direct Reactive Power Control (DRPC) and fuzzy logic controls techniques is applied to the proposed topology. In this work, two topologies are proposed. In the first one, the active power injected into the grid is smoothened by using an economical hybrid battery and supercapacitor energy storage system. However, in the second one, the excess wind energy is used to produce and store the hydrogen, and then a solid oxide fuel cell system (SOFC) is utilized to regenerate electricity by using the stored hydrogen when there is not enough wind energy. To avoid overcharging, deep discharging of batteries, to mitigate fluctuations due to wind speed variations, and to fulfil the requirement of the load profile, a power management algorithm is implemented. This algorithm ensures smooth output power in the first topology and service continuity in the second. The modelling and simulation results are presented and analysed using Matlab/Simulink.

Stability Improvement of Electric Ship Propulsion System Using Supercapacitor

Owing to the serious greenhouse gas emissions and inflexible control of traditional ship propulsion system, the electric ship propulsion system has been widely introduced into the ship’s power system. However, the variations of ship propellers will lead to the instability of electric propulsion system so this paper studied the transient characteristics of electric ship propulsion system by performing a series of experiments on a real electric ship propulsion system platform. Based on the experimental results, a detailed model of supercapacitor energy storage system (SCESS) is proposed to improve the voltage and frequency response for the electric ship propulsion system. To enhance the stability and reliability, a double closed-loop control method combined with Pulse-Width Modulation algorithm (PWM) is utilized to control the energy storage system for smoothing the power fluctuations caused by the electric propulsion system. The simulation results demonstrate the high efficiency of supercapacitor to improve the transient stability of the whole power system of the ship.