Control Of Storage System Research Articles

Modeling and control of dynamic battery storage system used in hybrid grid

AbstractIn renewable energy‐based grids, the most challenging tasks are to achieve uninterrupted, reliable, and continuous power supply from these grids. From literature, the problems in these grids and their associated solutions are (a) discrepancy between generation and demand: this is resolved by hybrid solar‐wind battery storage system (BSS), (b) requirement of improved efficiency and reliability: this is achieved by the use of state‐of‐the‐art controllers and innovative switching systems, (c) analysis of dynamic systems, optimization, and control: for these, mathematical modeling of systems is prepared, which is a tough task as solar, wind, and battery system contain nonlinear parameters. This article focuses on modeling and simulation of the wind turbine, photovoltaic (PV) arrays, and dynamic BSS. Moreover, control of variable speed wind turbines with pitch angle control, output power improvement of PV systems, and State‐of‐Charge (SoC) estimation of BSS with its characteristics parameters, temperature effects are analyzed in this work. The dynamic controller is provided which controls the charging/discharging of battery with the change in load, the power output of wind and solar system and makes the system reliable and efficient. In the result section, comparison of battery voltage and SoC is made by considering and neglecting the temperature effect.

Combined Control of DFIG-Based Wind Turbine and Battery Energy Storage System for Frequency Response in Microgrids

This paper presents a novel methodology for frequency control of a microgrid through doubly fed induction generator (DFIG) employing battery energy storage system (BESS) and droop control. The proposed microgrid frequency control is the result of the active power injection from the droop control implemented in the grid side converter (GSC) of the DFIG, and the BESS implemented in the DC link of the back-to-back converter also in the DFIG. This methodology guarantees the battery system charge during operation of the connected DFIG in the network, and the frequency control in microgrid operation after an intentional disturbance. In order for the DFIG to provide frequency support to the microgrid, the best-performing droop gain value is selected. Afterwards its performance is evaluated individually and together with the power injected by the battery. The power used for both battery charging and frequency support is managed and processed by the GSC without affecting the normal operation of the wind system. The simulation tests are performed using Matlab/Simulink toolbox.

A deep reinforcement learning method for managing wind farm uncertainties through energy storage system control and external reserve purchasing

In deregulated environment, the wind power producers (WPPs) will face the challenge of how to increase their revenues under uncertainties of wind generation and electricity price. This paper proposes a method based on deep reinforcement learning (DRL) to address this issue. A data-driven controller that directly maps the input observations, i.e., the forecasted wind generation and electricity price, to the control actions of the wind farm, i.e., the charge/discharge schedule of the relevant energy storage system (ESS) and the reserve purchase schedule, is trained according to the method. By the well-trained controller, the influence of the uncertainties of wind power and electricity price on the revenue can be automatically involved and an expected optimal decision can be obtained. Furthermore, a targeted DRL algorithm, i.e., the Rainbow algorithm, is implemented to improve the effectiveness of the controller. Especially, the algorithm can overcome the limitation of the conventional reinforcement learning algorithms that the input states must be discrete, and thus the validity of the control strategy can be significantly improved. Simulation results illustrate that the proposed method can effectively cope with the uncertainties and bring high revenues to the WPPs.

Using Bidirectional Converters in a Traction Drive

Modern means of power electronics are promoting a transition from standard locomotives with diesel motors and electric locomotives to traction drives with asynchronous motors and permanent magnet motors, as well as hybrid electric vehicles. This article focuses on unique aspects of power electronics related to hybrid electric vehicle applications. The efficacy of using a bidirectional converter in a connecting energy accumulating device, a battery or supercapacitors with a dc bus of a traction motor, and matching voltage of an energy storage system and traction motor control system is considered.

The Influence of the Solar Flywheel Energy Storage Control System Based on the Improved Disturbance Observation Method on the Improvement of New Energy Efficiency

The purpose of this study was to improve the utilization efficiency of solar energy, and accelerate the innovation and development of solar flywheel energy storage control system, so as to enhance the utilization value of new energy. Firstly, the definition and working method of flywheel energy storage control system were described, and the characteristics of flywheel energy storage control system were introduced in detail. Secondly, the concept and working principle of solar flywheel energy storage control system were introduced, and the principle and calculation method of perturbation and observation method (P&O) were described in detail. Finally, the improved P&O based on particle swarm optimization (PSO) algorithm was described in detail, and its principle and operation methods were explained. The research results show that the biggest characteristic of flywheel energy storage device is that it has no pollution to the environment, the energy stored per unit area is large, and the efficiency of converting it into electric energy is very high, which can be used for a long time. The working property of solar energy storage system is the introduction, maintenance, and output of electric energy. In order to obtain the best tracking data, the flywheel energy storage control system must control the disturbance amplitude and time accurately and make a comprehensive choice. The P&O improved by PSO algorithm is applied to the flywheel energy storage control system, and the experience time to reach the maximum efficiency position is relatively shortened. When the system’s derived power reaches the balance, the variation of wave shape in the improved dynamic observation method is also relatively reduced.

DC bus voltage control strategy based on hybrid energy storage

In view of the fluctuation of DC bus voltage caused by the load change of power system, a method based on hybrid energy storage system control is proposed to stabilize the bus voltage of microgrid. Based on the complementary characteristics of battery and supercapacitor, the voltage division strategy is adopted to improve the DC bus voltage. The simulation results show that the method can stabilize the voltage of DC bus.

Research on fuel cell energy storage control and power generation system

In order to realize the continuous stability of photovoltaic power generation system and the controllability of thermal energy storage, a photovoltaic fuel cell combined power generation system consisting of photovoltaic cell array, proton exchange membrane fuel cell, alkaline electrolysis cell and super capacitor is proposed. The system, at the same time, establishes the mathematical model of its various components and the system cost model, designs the thermal energy distribution of the thermal energy storage management coordination system, and uses the high efficiency battery to meet the load requirements of the power system. In addition, the paper uses simulation technology as a research method to build a simulation model of hybrid fuel cell thermal energy storage control and power generation system, and analyzes the system?s thermal energy supply and demand balance. The simulation results confirm that the photovoltaic fuel cell hybrid power generation system has high economic performance, can meet the user?s power and thermal energy requirements, and realizes the requirement of completely independent power supply.

Novel Droop Control of Battery Energy Storage Systems Based on Battery Degradation Cost in Islanded DC Microgrids

This paper presents a new droop control method to reduce battery degradation costs in islanded direct current (DC) microgrids for multiple battery energy storage systems (BESSs). BESSs may have varying installation costs and battery cycle life characteristics depending on battery type, energy capacity, and maximum output power. These differences cause different battery degradation costs among BESSs despite exchanging the same amount of energy. To autonomously reduce the total battery degradation cost, an incremental cost (IC) of a BESS is used as a criterion for determining the state-of-charge level of BESSs and is calculated based on the battery cycle life curve containing the battery degradation information. By adopting an IC–voltage droop control, the BESSs can maintain an operating point of equal IC, an optimal point for cost minimization. Subsequently, small-signal stability analysis is performed using the state-space model of the proposed method. The case study validates that the proposed method can reduce the total battery degradation cost with a small-signal stable operation in islanded DC microgrids.

Cooperative Control of A Flywheel Energy Storage System with Identical Damping

Motivated by the work of Cai and Hu (2018), this paper considers the dual objective control problem of a flywheel energy storage system targeting simultaneous state-of-energy balancing and reference power tracking. It is first shown that, in the presence of flywheel damping, the steady state solution subject to the dual control objective exists and is defined by a virtual dynamic system. Second, under the identical damping condition, it is proven that the control law proposed in Cai and Hu (2018) can still solve the dual objective control problem.

Formulation and simulation of a hybrid solar PV-wind generation system with photovoltaic concentration for non-interconnected areas to the energy grid

Different isolated systems with conventional generation sources are installed in Non-Interconnected Areas (ZNI) in Colombia while off-grid renewable systems are a trending answer for the energy supply in these regions. The complementarity between different energy sources, a storage system and adequate control can substantially improve the reliability of isolated generation systems. In this context, the sizing of a Hybrid Renewable Energy System (HRES) by means of a Genetic Algorithm (GA) is presented, considering the wind and solar resources specific to a representative rural location in Colombia. The methodology involves power curves for small wind turbines and the model for photovoltaic solar panels. The preliminary output consists of a weighted distribution for each technology, either wind or conventional photovoltaics, and is constrained by the Loss of Power Supply Probability (LPSP) and the Levelized Cost Of Electricity (LCOE). A second step consists of the optimization of the installed area for photovoltaic generation, considering a Concentrated Photovoltaic (CPV) system and aiming to maintain the initial fraction of generation for this resource. Finally, an analysis is performed on the reduction of area for solar generation to the increase in costs derived from the use of concentrators and other penalties associated with this technology.

Study on Hybrid Energy Storage Configuration and Control Strategy of Grid-connected Wind Hydrogen System

The randomness and volatility of wind energy bring great challenges to wind power grid-connected. The hybrid energy storage technology based on electrolysis cell hydrogen production and super capacitor has become an effective way to stabilize wind power fluctuations. Based on the establishment of the grid-type wind-hydrogen coupling system working characteristic constraint and the minimum initial investment cost of the hybrid energy storage system, an alkaline electrolytic cell-super capacitor hybrid storage based on low-pass filtering-fluctuation observation is proposed. The method can be configured, and a hybrid energy storage coordinated control strategy based on the super capacitor SOC (state of charge) is developed. The case study results show that the hybrid energy storage system configuration method and control strategy proposed in this paper are effective, which can reduce the fluctuation of wind power grid-connected power to meet the grid connection standard.

Optimal Operation Strategy of ESS for EV Charging Infrastructure for Voltage Stabilization in a Secondary Feeder of a Distribution System

The introduction of electrical vehicle charging infrastructure including electric vehicle (EV) charger renewable energy resource at the secondary feeder in a distribution system has been increased as one of countermeasure for global environmental issues. However, the electric vehicle charging (EVC) infrastructure may act as the peak load in the distribution system, which can adversely impact on the voltage stability when the electric vehicle is quickly charged. Therefore, to keep within the limit capacity of a secondary feeder and allowable limit for the feeder voltage, this paper proposes a stabilization method by an energy storage system (ESS) control strategy at the secondary feeder to not exceed the upper limit or fall below the lower limit. In addition, this paper presents an estimation method to keep the proper standard value of the state of charge (SOC). From the simulation results, the voltage stabilization operation by the ESS should make the feeder voltages of the distribution system (secondary feeder) introduced EVC infrastructure keep better voltage conditions. In addition, the estimation method was able to keep the proper standard value confirming that the SOC of the ESS when it is in standby can be kept within the proper reference range. Therefore, it is confirmed that this strategy is an effective tool to solve the voltage problems by ESS.

Practical Considerations For Customer-sited Energy Storage Dispatch On Multiple Applications Using Model Predictive Control

Government subsidies for energy storage and renewable generation have led to the cost of energy storage come down during recent years. This has motivated people to deploy behind-the-meter energy storage units, to reduce their monthly electricity bill. For optimal control of the battery to incorporate maximum photovoltaic energy generation as well as demand charge reduction, data-driven and advanced Battery Energy Storage System (BESS) control strategies are required. This paper explores different use cases where customers could deploy energy storage systems for demand charge reduction as well as when customers could deploy energy storage systems for demand charge reduction while satisfying a utility set objective. From historical load and PV data, different use cases are simulated using a Model Predictive Control (MPC) based BESS control model. MPC requires machine-learning (ML) based forecasts of photovoltaic (PV) as well as load as inputs. A sensitivity analysis on the effect of different energy forecasts on the performance of MPC is presented in the paper. A degradation analysis with as a function of charge/discharge cycles is also presented in the paper to evaluate the trade-off between economic objectives and battery health.

An Adaptive Power Oscillation Damping Controller for a Hybrid AC/DC Microgrid

High penetration of dynamic loads, such as induction motors (IMs) could give rise to sustained voltage/frequency and power oscillations in hybrid AC/DC microgrids during disturbances. Majority of the published literature has investigated these stability issues with aggregated models of IMs in hybrid AC/DC microgrids, which do not properly reflect the actual dynamics of parallel operating IMs; hence, power oscillation damping (POD) controllers must be designed explicitly considering various oscillations induced by parallel operating IMs. This paper proposes an adaptive neuro-fuzzy inference system (ANFIS) based POD controller to damp low-frequency oscillations (LFOs) induced by IMs in hybrid AC/DC microgrids. The proposed supplementary POD controller was embedded to the energy storage system (ESS) controller, which provides additional damping power proportional to the frequency deviation. The following two features namely: 1) ability to adjust the gain based on the frequency deviation, and 2) ability to handle more non-linearity in the system dynamics, make the proposed adaptive ANFIS based POD controller more unique compared to conventional POD controllers. The effectiveness of the proposed ANFIS-POD controller is verified using non-linear dynamic simulations considering a range of disturbances in a hybrid AC/DC microgrid and different combinations of parallel operating IMs. Results indicate improved oscillatory stability performance in the hybrid AC/DC microgrid with the proposed ANFIS-POD controller.

Performance Analysis of a Dq Power Flow-Based Energy Storage Control System for Microgrid Applications

This paper presents a dq power flow based energy storage control system for reliable and stable operation of a renewable power generation based microgrid system. The control objectives are storing the excess energy from the microgrid into the storage unit or supplying energy deficit from the storage unit to the microgrid to achieve power equity between the generation and load, and regulation of voltage and frequency during stand-alone microgrid operation. Whereas during grid-connected microgrid operation, the control objective is to ensure storing energy in the storage unit and exchange power between the microgrid and the utility grid. The proposed controller is developed for inverter interface energy storages using dq power flow. The dq power flow is formulated using bus voltage components and the bus admittance matrix in dq frame. The dq power flow in the developed controller generates command (reference) active and reactive powers for the inverter interfaced storage unit connected to the microgrid buses. In addition, the implemented current controller of the inverter assures such command powers exchange between the storage unit and the microgrid. The developed dq power flow based storage unit (DQPFSU) control system is tested under various operating conditions for both in grid-connected and stand-alone microgrid operation. The test results of the developed DQPFSU controller illustrates satisfactory performance in generating fast control actions to ensure reliable and stable microgrid operation under various changing conditions. Moreover, the validity of such control actions has examined from the frequency response and bus voltages of the case study microgrid under various tested operational conditions.

Research on thermal energy control of photovoltaic fuel based on advanced energy storage management

This paper proposes a photovoltaic fuel cell power generation system to convert solar thermal energy into electrical energy after storage. The energy conversion method of the system mainly utilizes hydrogen storage to realize long-term storage of thermal energy, and realizes continuous and stable power supply through the co-operation between the micro-gas turbine and the proton exchange membrane fuel cell. Based on the model of each component, the simulation platform of photovoltaic fuel cell hybrid thermal energy storage control power generation system is built. Based on the design principle and design requirements of photovoltaic power generation system, the photovoltaic fuel cell hybrid power generation system studied in this paper has a simple capacity. Match the design and conduct thermal energy storage management research on the system according to the system operation requirements. The paper studies the management of hybrid fuel energy storage control system for photovoltaic fuel cells. The paper is based on advanced thermal energy storage management for photovoltaic prediction and load forecasting, and through the organic combination of these three layers of thermal energy storage management to complete the thermal energy storage management of the entire system. Finally, the real-time thermal energy storage management based on power tracking control is simulated and analyzed in MATLAB/Simulink simulation environment.

Research on fuel cell based on photovoltaic technology

To investigate the hybrid thermal energy storage in photovoltaic fuel cells, a hybrid thermal energy storage control system for photovoltaic fuel cells is explored model construction and simulation. The correlations between the system components and the external factors are analyzed. The results show a positive correlation of the state of charges between the storage battery and the hydrogen storage tank at 0-15 hours, while no correlation exists between them at 15-35 hours. Meanwhile, the sunshine intensity and the photovoltaic output share a positive correlation. In summary, the hybrid thermal energy storage system is critical for photovoltaic fuel cells. The charging and discharging of the battery depends on the photovoltaic intensity. The constructed grouping management model for storage battery is outstanding and satisfies the operational requirements of photovoltaic fuel cells.

Hybrid energy storage system control method based on model predictive control

The traditional PI controller for a hybrid energy storage system (HESS) has certain drawbacks, such as difficult tuning of the controller parameters and the additional filters to allocate high- and low- frequency power fluctuations. This paper proposes a model predictive control (MPC) method to control three-level bidirectional DC/DC converters for grid-connections to a HESS in a DC microgrid. First, the mathematical model of a HESS consisting of a battery and ultra capacitor (UC) is established and the neutral point voltage imbalance of a three-level converter is solved by analyzing the operating modes of the converter. Secondly, for the control of the grid-connected converters, an MPC method is proposed for calculating steady-state reference values in the outer layer and the dynamic rolling optimization in the inner layer. The outer layer ensures the voltage regulation and establishes the current predictive model, while the inner layer, using the model predictive current control, makes the current follow the predictive value, thus reducing the system current ripple. This cascaded topology has two independent controllers and is free of filters to realize the high-and low- frequency power allocation for a HESS. Therefore, it allows two types of energy storage devices to independently regulate the voltage and realizes the power allocation of the battery and UC. Finally, simulation studies are conducted in PSCAD/EMTDC, and the effectiveness of the proposed HESS control strategy is verified in a case, such as a controller comparison and fault scenario.

TRADEOFF ANALYSIS OF HIGH-POWER ELECTRIC PROPULSION SYSTEMS BASED ON DOMESTIC ELECTRIC PROPULSION ENGINES AND POTENTIAL FOR THEIR USE IN ORBIT-TO-ORBIT TRANSFER SYSTEMS AND DEEP SPACE EXPLORATION

The paper discusses design solutions for increased-power and high-power electric rocket propulsion systems to be used in orbit-to-orbit transfer vehicles and advanced spacecraft. It reviews characteristics of their components from the standpoint of the mission to reboost the spacecraft to their target orbits, to perform the operations of transportation to the lunar orbit and to explore deep space. It discusses key criteria and procedures for selection of components, as well as problem areas in their development and ground developmental testing. The paper analyses pros and cons of using various versions of propulsion systems based on medium- and high-power electrical propulsion engines, the current status of their component development, as well as the technical feasibility of conducting developmental tests on the ground. Key words: electric propulsion engine, propulsion system, propulsion module, propellant storage system, power supply and control system, vacuum chamber, vacuum system.

Design and Implementation of Cascaded Multilevel qZSI Powered Single-Phase Induction Motor for Isolated Grid Water Pump Application

This article presents the design and implementation of solar-powered V/f controlled single-phase capacitor-start induction motor. Multilevel quasi impedance source inverter controls the power flowing from the photovoltaic (PV) array to a single-phase induction motor. In solar powered drive systems, the main concern is stable intended operation of drive when subjected to variations in power generation of the PV array. For same environmental conditions, the PV power extraction is different at different torques for constant speed application. Due to this, the extraction of maximum power with an MPPT algorithm is not achieved with only motor load. To address this concern, concept of the battery storage system is introduced in the system that helps in achieving maximum power when the PV power generation capability exceeds rated motor input power. In addition to this, battery storage system can supply power to the load when the PV power generation is less than the rated motor input power. Conclusively, the design of control algorithm must address issues of the MPPT algorithm, control of battery storage system, and stable operation of V/f-controlled induction motor drive operation. MATLAB/Simulink model of the proposed system with 4 kW PV array rating is developed. The proposed control algorithm achieves satisfactory operation of single-phase motor drive in all the three operation modes (depending upon PV power generation). The variation of the solar irradiation and temperature are simultaneously considered for introducing perturbation in the PV power generation. Hardware results for this system are also presented, which validates the effectiveness of the control algorithm for the proposed system.