A microgrid (MG) is a local entity that consists of distributed energy resources (DERs) to achieve local power reliability and sustainable energy utilization. The MG concept or renewable energy technologies integrated with energy storage systems (ESS) have gained increasing interest and popularity because it can store energy at off-peak hours and supply energy at peak hours. However, existing ESS technology faces challenges in storing energy due to various issues, such as charging/discharging, safety, reliability, size, cost, life cycle, and overall management. Thus, an advanced ESS is required with regard to capacity, protection, control interface, energy management, and characteristics to enhance the performance of ESS in MG applications. This paper comprehensively reviews the types of ESS technologies, ESS structures along with their configurations, classifications, features, energy conversion, and evaluation process. Moreover, details on the advantages and disadvantages of ESS in MG applications have been analyzed based on the process of energy formations, material selection, power transfer mechanism, capacity, efficiency, and cycle period. Existing reviews critically demonstrate the current technologies for ESS in MG applications. However, the optimum management of ESSs for efficient MG operation remains a challenge in modern power system networks. This review also highlights the key factors, issues, and challenges with possible recommendations for the further development of ESS in future MG applications. All the highlighted insights of this review significantly contribute to the increasing effort toward the development of a cost-effective and efficient ESS model with a prolonged life cycle for sustainable MG implementation.

/pdf/review-of-energy-storage-system-technologies-in-microgrid-13f9i4hnhx.pdf

Review of Energy Storage System Technologies in Microgrid Applications: Issues and Challenges

https://pure.hw.ac.uk/ws/files/15657125/Dynamic_Power_Allocation_of_Battery_Supercapacitor_Hybrid_Energy_Storage_for_Standalone_PV_Microgrid_Applications.pdf

Dynamic power allocation of battery-supercapacitor hybrid energy storage for standalone PV microgrid applications

Optimal sizing of hybrid energy storage sub-systems in PV/diesel ship power system using frequency analysis

This study presents an approach of the voltage regulation of DC bus for the photovoltaic energy storage by using a combination of batteries and supercapacitors (SCs). The batteries are used to meet the energy requirements for a relatively long duration, whereas the SCs are used to meet the instantaneous power demand. The energy management strategy is developed to manage the power flows between the storage devices by choosing the optimal operating mode, thereby to ensuring the continuous supply of the load by maintaining the state-of-charge (SoC) of SCs (SoC
 sc
) and the SoC of the batteries (SoC
 bat
) at acceptable levels. This energy management strategy is performed by using the fuzzy logic supervisor. The validation results prove the effectiveness of the proposed strategy.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rpg.2016.0455

Battery and supercapacitor for photovoltaic energy storage: a fuzzy logic management

Hybrid energy storage systems (HESSs) have become an effective solution for smoothing the active power variations of photovoltaic (PV). In order to reduce the required capacities and costs of the HESS, a coordinated control scheme is developed to mitigate the power variations of a PV plant by using the HESS and the active power curtailment (APC) of PV. Furthermore, a multi-objective optimization model is established to dispatch the output power of batteries and supercapacitors, considering the overall losses and the state-of-charge (SOC) deviation of the supercapacitor. Based on the proposed smoothing strategy, an allocation model is developed to optimize the energy and power capacities of the HESS with the aim of maximizing the annual net income of the PV and HESS plant. The numerous simulations are carried out to verify the effectiveness of the proposed smoothing and allocation methods by using the real data of a PV plant. In addition, we also discuss the impacts of the different dispatching strategies of the HESS, grid requirements of power variations, and solution methods on the HESS allocation results.

/pdf/optimal-allocation-of-hybrid-energy-storage-systems-for-31vljm6c83.pdf

Optimal Allocation of Hybrid Energy Storage Systems for Smoothing Photovoltaic Power Fluctuations Considering the Active Power Curtailment of Photovoltaic

Battery/supercapacitor (SC) hybrid energy storage system (HESS) is an effective way to suppress the power fluctuation of photovoltaic (PV) power generation system during radiation change. This study focuses on the power sharing between different energy storage components with two optimisation objectives: energy loss and state of charge of SC. First, the topology of HESS and its connection with PV system are analysed. Second, the control targets of the HESS have been organised as optimisation objectives. A linear weighted summation algorithm based on variable weights is proposed to solve the multi-objective optimisation problem to obtain current reference of SC and battery. Third, the energy management system of the HESS is designed based on proposed algorithms. Simulation and experiment results verified the proposed algorithms and control strategy.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rpg.2015.0199

Research on power sharing strategy of hybrid energy storage system in photovoltaic power station based on multi-objective optimisation

The invention provides a device and method for charging a super capacitor. The charging efficiency of a charging power supply on the super capacitor can be improved by using the method for charging the super capacitor to charge the super capacitor. The charging method comprises the following steps of: a, using a soft start charging mode during a charging starting period; b, using a current limiting charging mode when product of a terminal voltage of the super capacitor and maximal charging current allowed by the super capacitor is less than maximal charging power provided by the charging power supply; and c, using a constant power charging mode when product of the terminal voltage of the super capacitor and the maximal charging current allowed by the super capacitor is more than the maximal charging power provided by the charging power supply.

Device and method for charging super capacitor

The utility model provides a charging device for a super capacitor, and is characterized in that: a detection unit (201) comprises a voltage sensor and a current sensor, and is used for detecting a terminal voltage, a charging current and a charging power supply maximum charging power of a super capacitor CL; a charging control chip (202) comprises an inner core, a sampling holder, a pulse width modulation module, and a universal interface; wherein the sampling holder in the charging control chip (202) is connected with the detection unit (201), and is used for calculating a charging current for the super capacitor CL according to the detected voltage value, the detected current value, and the detected power value; an output end of the pulse width modulation module is connected with a control end of a switching device Q in a DC (Direct Current) chopping circuit (203), the pulse width modulation module is used for sending a control command to the switching device Q in the DC chopping circuit (203), and controlling on-off of a short switch (205) through the universal interface. By adopting the charging device for the super capacitor in the utility model to charge the super capacitor, a charging efficiency of a charging power supply to the super capacitor can be raised.

Charging device for super capacitor

The invention discloses a cascading multi-level super capacitor energy storage system and a discharge mode control method. The system comprises at least two half-bridge converters, super capacitor energy storage units, an LC series circuit, a voltage detection unit and a controller, wherein the input end of each half-bridge converter is connected with one super capacitor energy storage unit in parallel, the half-bridge converters are connected between the anode and the cathode of a common direct current bus in a cascading manner, the LC series circuit is connected between the positive terminal of the output end of the first half-bridge converter and the negative terminal of the output end of the last half-bridge converter in parallel, the voltage detection unit is used for transmitting the end voltage of anode of the common direct current bus and end voltages of super capacitors to the controller, the controller is used for controlling each half-bridge converter to output a direct current power component and output/input a high-frequency alternating current component, the direct current power components are supplied to a load through the common direct current bus, and the high-frequency alternating current components flow between the cascading half-bridge converters and the LC series circuit for balancing energy of the super capacitors.

Cascading multi-level super capacitor energy storage system and discharge mode control method

The invention discloses a chained hybrid energy storage system with an LC tuned filter and a control method thereof The chained hybrid energy storage system comprises a chained hybrid energy storage structure formed by a capacitor power unit, a super capacitor energy storage unit and a storage battery energy storage unit, and the LC tuned filter which is connected with the chained hybrid energy storage structure so as to form an auxiliary power loop circuit The chained hybrid energy storage system controls each unit by outputting a PWM (pulse width modulation) modulating wave, wherein the modulating wave is composed of two portions which are respectively a power frequency modulating wave and a high frequency modulating wave The power frequency modulating wave controls power frequency alternating voltage and current output of the energy storage system The high frequency modulating wave controls power to transfer among all the units through the auxiliary power loop circuit, wherein the super capacitor energy storage unit charges the capacitor power unit through the auxiliary power loop circuit so as to keep terminal voltage of the capacitor power unit stable, when current output of the storage battery energy storage unit is insufficient, the super capacitor energy storage unit provides the power for the storage battery energy storage unit through the auxiliary power loop circuit, and when residual energy of a super capacitor is insufficient, a storage battery charges the super capacitor through the auxiliary power loop circuit

Huichun Huang

Papers

Research on power sharing strategy of hybrid energy storage system in photovoltaic power station based on multi-objective optimisation

Device and method for charging super capacitor

Charging device for super capacitor

Cascading multi-level super capacitor energy storage system and discharge mode control method

Chained hybrid energy storage system with LC tuned filter and control method thereof