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Fuzzy-based Energy Management System for a MVDC PV Power Plant with Battery Stored Quasi-Z-Source Inverter
The energy-stored quasi-Z-source inverter (ES-qZSI) has attracted much attention for photovoltaic (PV) power generations, due to its capability to stabilize the PV power fluctuations with simple structure and other advantages of Z-source inverter. The improved dual-mode (DM) ES-qZSI is able to support all-weather operation even at night or cloudy days when PV power is extremely low. Whereas, the traditional proportional-integral (PI) based control suffers from complicated controller design and poor dynamic response during mode transition, due to two sets of PI control required for the daytime and night operation modes. In order to overcome that, this paper proposes a model predictive control strategy for the DM-ES-qZSI PV power system. The system predictive models in both day and night operating modes are derived. The control strategy is disclosed to ensure high performance of the system, through calling the predictive models and defined cost functions of the two modes within a single control loop. Simulation and experiment are carried out to verify the effectiveness of proposed control strategy.
Lithium-ion batteries have recently been in the spotlight as the main energy source for the energy storage devices used in the renewable energy industry. The main issues in the use of lithium-ion batteries are satisfaction with the design life and safe operation. Therefore, battery management has been required in practice. In accordance with this demand, battery state indicators such as the state-of-charge (SOC), state-of-health (SOH), state-of-function (SOF), and state-of-temperature (SOT) have been widely applied. The use of these indicators ensures safe operation without overcharging and over-discharging. In addition, it can also help satisfy the design life. This paper presents a literature review of battery state indicators over the last three years and proposes the requirement of state-of-the-art battery state indicators. It also suggests future developments for battery management system (BMS) in stationary energy storage systems (ESSs).
Increasing Renewable Energy Sources (RES), impact the power system. Moreover, the system equilibrium and stability are difficult because constant generation cannot be generated from RES concerning conventional energy sources. This paper studies the effect of RES on the power system through the actual application of the Egyptian power system. The strategy of the Egyptian power system aims at increasing the proportion of RES, especially, Wind Power (WP) and photovoltaic (PV). Therefore, Different operation scenarios are presented to illustrate the impact of RES on the Egyptian network. Also, the economic and environmental benefits of increasing the Penetration of Renewable Power Generation are presented by calculating the expected annual reductions of CO2 emission (ER), certified emission reduction (CER) and the fuel-saving amount. Therefore, how to decrease the cost of electricity (DCOE) model when calculating the cost-benefit analyses from RES. The results show the economic benefits of the point of view of the amount of savings achieved when bringing renewable energy to each scenario. Finally, the economic study shows the benefits renewable energy sources have provided, where the RES by the end of 2022 will reduce the emission of carbon dioxide to 46405×103 tCO2 which yield a return of 433427.6×103 $ according to CER price and the savings of the fuel will reach 19066 ktoe. The model was created using DIgSILENT power factory software. Keywords: Wind, Photovoltaic, Economic, Fuel consumption, CO2 emission
This paper suggests improved control strategies using Fuzzy Gain Scheduling of Proportional-Integral-Derivative (FGS-PID) controller for a hybrid Photovoltaic (PV) and Battery Energy Storage (BES) system under different weather conditions. The proposed scheme is implemented using a two-level control system structure, combining the benefits of the PID as well as the fuzzy logic controller (FLC) for maximum power point tracking (MPPT). Ziegler-Nichols tuning method is also employed to select the initial values of PID gains. Within the period of steady-states and transients, FGS-PID adopts the gains to ensure the stability of the control scheme. It also damps out transient fluctuations and reduces settling time. Also, BES could be employed to provide a stable and reliable power from the output of PV sources to loads. It can enhance the performance of the entire power system during the grid-connected mode. The simulation results under Matlab/Simulink show that the suggested control strategies are robustness, fast transient response and proper steady-state performance in the grid-connected mode in comparison other presented methods.
Hybrid renewable energy systems (HRES) are attractive configurations used for different applications and especially in standalone power generation systems as electrification, water pumping, and telecommunications. Considering the multitude of sources, energy management control (EMC) will be necessary. In this paper, supervision of hybrid Wind/Photovoltaic/Diesel system with battery storage is presented. The power balance of the suggested system is made on an intelligent supervisor based on fuzzy logic control (FLC). It is simple, easy and makes it possible to determine the various operating processes of the hybrid system according to the weather conditions. The decisions of criterion required by this method are presented. The study was implemented under Matlab/Simulink and an application is made for Bejaia a site in the coastal region of Algeria. The obtained results are presented and show the feasibility of the proposed control system.
This paper highlights the modeling and the simulation of a micro-grid renewable power system. It comprises wind turbine (WT) doubly fed induction generators (DFIGs), photovoltaic generator (PV), a proton exchange membrane (PEM) fuel cell (FC) generator, a water electrolyzer used for long-term storage, a Hydrogen tank, and a battery bank (BB) utilized for short-term storage. Based on the given configuration and the different characteristics of the main components in the micro-grid, an overall control and a power management strategy are proposed for this system. This strategy consists in charging the BBs and producing hydrogen from the water electrolyzer in the case of excess power from the WT-DFIGs and PV generators. Therefore, the FC and the BBs will be used as a backup generator to supply the demand required power, when the WT-DFIGs and the PV energy are deficient. The effectiveness of this contribution is verified through computer simulations, where very satisfactory results are obtained.
This paper highlights the modeling and the simulation of a micro-grid renewable power system. It comprises a wind turbine (WT) doubly fed induction generators (DFIG), photovoltaic generator (PV), a proton exchange membrane (PEM) Fuel Cell (FC) generator, a water Electrolyzer, a Hydrogen tank, and a battery banks (BBs). The system configuration and the characteristics of the main components in the proposed system are given; and the overall control and power management strategy for this latter are presented. In addition, the dynamic models of a boost DC-DC converter and a bidirectional DC-DC (Buck-Boost) converter are considered. A battery bank (BB) is used for short-term energy storage and an electrolyzer is used for long-term energy storage. The excess power from the WT-DFIGs and PV generators is then used for charging BB and for water electrolyzer to produce hydrogen. The (FC) and the (BB) work as a backup generator to supply the demand required power, when the WT-DFIGs and the PV energy are deficient. All the work is undertaken under Matlab/Simulink environment.
Impedance networks cover the entire of electric power conversion from dc (converter, rectifier), ac (inverter), to phase and frequency conversion (ac–ac) in a wide range of applications. Various converter topologies have been reported in the literature to overcome the limitations and problems of the traditional voltage source, current source as well as various classical buck–boost, unidirectional, and bidirectional converter topologies. Proper implementation of the impedance-source network with appropriate switching configurations and topologies reduces the number of power conversion stages in the system power chain, which may improve the reliability and performance of the power system. The first part of this paper provides a comprehensive review of the various impedance-source-networks-based power converters and discusses the main topologies from an application point of view. This review paper is the first of its kind with the aim of providing a “one-stop” information source and a selection guide on impedance-source networks for power conversion for researchers, designers, and application engineers. A comprehensive review of various modeling, control, and modulation techniques for the impedance-source converters/inverters will be presented in Part II.
The quasi-Z-source inverter (qZSI) with battery can balance the stochastic fluctuations of PV power injected to the grid/load, but there is no literature to disclose its modelling and controller design in detail. This study proposed a dynamic small-signal model of qZSI with battery and a control strategy for photovoltaic (PV) power generation system. The built model discloses the dynamic relationship of PV panel voltage, battery current, quasi-Z-source inductor currents and capacitor voltages. The proposed control method achieves the grid-tie operation with unity power factor, PV panel??s maximum power point tracking and battery management. The novel space vector modulation for the qZSI divides the total shoot-through time interval into six equal parts per control cycle to be combined into the six switching moments, and lower inductor current ripple and higher inverter efficiency are performed. The experimental and simulation results verify the theoretical analysis and proposed control methods.
The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system.
This review article critically highlights the latest trends in energy storage applications, both cradle and grave. Several energy storage applications along with their possible future prospects have also been discussed in this article. Comparison between these energy storage mediums, as well as their limitations were also thoroughly discussed. Suggestions and solutions in mitigating some of these challenges in order to improve the overall performance of these energy systems have also been analysed in this investigation. In spite of the accelerated growth in energy storage systems, there is still a grave need for further investigations, in order to reduce their costs. Further research activities will reduce the cost of some of these novel technologies, thereby accelerating their commercialization as well as making them better competitors against traditional energy storage mediums.
This paper presents an improved performance of coordinated control scheme for exchanging power between a single phase electrical grid and battery energy storage system (BESS) using adaptive neuro-fuzzy inference system (ANFIS). The grid connected BESS has several practical applications in respect of storage of excess energy, reduction of maximum demand and reduction of power fluctuation on local grid/micro-grid. In these scenarios, the coordinated closed loop control strategy facilitates charging and discharging operation of the battery via dc-ac bidirectional converter. During charging mode of operation, the grid supplies active power to the battery for restoring back its energy. On the other hand, the closed loop action is also capable to control active and reactive power in decoupled way by discharging battery and the required electrical powers can be injected into the nearby grid conveniently. At first, the required closed loop control schemes are implemented using proportional-integral (PI) controller and the performance of the BESS using PI based control schemes is investigated. Then, the ANFIS based control strategy is used for improving overall control capability and it provides superior dynamic performance in comparison to the PI based control scheme under charging and discharging operation cycle of the battery. Various simulation studies are performed on 230 V, 50 Hz single phase ac grid connected 100 Ah, 120 V battery using MATLAB-SIMULINK 2014b software to validate the improved control concept.
Power system blackouts harm economic activities and worsen the customers’ welfare. Smart grids’ self-healing capacity is an important feature for future power systems and it should also include the ability to manage the distributed energy resources to ensure power supply for a longer time. This is required because the duration of a blackout is unknown and bulk power system blackstart is a complex task. The deployment of microgrids can overcome these challenges since they may be operated in an autonomous way. This paper proposes a methodology for microgrid management in islanded conditions aiming to maximize the duration of power supply taking into account the availability of renewable sources and stored energy. In order to accomplish this goal, some management options are considered, such as load shedding, dispatch of expensive fossil fuel sources, and demand response actions. The control actions are determined with the help of a fuzzy logic methodology. The proposed approach is validated with a modified IEEE 34 node sample system.
This paper describes a new maximum-power-pointtracking method for a photovoltaic system based on the Lagrange Interpolation Formula and proposes the particle swarm optimization method. The proposed control scheme eliminates the problems of conventional methods by using only a simple numerical calculation to initialize the particles around the global maximum power point. Hence, the suggested scheme will utilize fewer iterations to reach the maximum power point. The proposed algorithm is verified with the OPAL-RT real time simulator and the Matlab Simulink tool, with several simulations being carried out, and compared to the Perturb and Observe method, the Incremental Conductance method, and the conventional Particle Swarm Optimization based algorithm. The simulation results indicate the proposed algorithm can effectively enhance stability and fast tracking capability under fastchanging non-uniform insolation conditions.
This paper presents a quasi-Z-source inverter (qZSI) that is a new topology derived from the traditional Z-source inverter (ZSI). The qZSI inherits all the advantages of the ZSI, which can realize buck/boost, inversion and power conditioning in a single stage with improved reliability. In addition, the proposed qZSI has the unique advantages of lower component ratings and constant dc current from the source. All of the boost control methods that have been developed for the ZSI can be used by the qZSI. The qZSI features a wide range of voltage gain which is suitable for applications in photovoltaic (PV) systems, due to the fact that the PV cell's output varies widely with temperature and solar irradiation. Theoretical analysis of voltage boost, control methods and a system design guide for the qZSI in PV systems are investigated in this paper. A prototype has been built in the laboratory. Both simulations and experiments are presented to verify the proposed concept and theoretical analysis.
The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW's has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion, lowered cost pr kW, and increased power density and the need for higher reliability. Substantial efforts are made to comply with the more stringent grid codes, especially grid faults ride-through and reactive power injection, which challenges power converter topologies, because the need for crowbar protection and/or power converter over-rating has been seen in the case of a doubly-fed induction generator. In this paper, power converter technologies are reviewed with focus on single/multi-cell power converter topologies. Further, case studies on the Low Voltage Ride Through demand to power converter technology are presented including a discussion on reliability. It is concluded that as the power level increases in wind turbines, medium voltage power converters will be a dominant power converter configuration.
Haitham Abu-Rub, Baoming Ge, Frede Blaabjerg, Omar Ellabban, Impedance Source Power Eletronic Converters
- P C L Liu
Day-ahead hourly price
- Omie
Overview of Space Vector Modulations for Three-Phase Z-Source/Quasi-Z-Source Inverters
- Yushan Liu
- B Ge
- H Abu-Rub
- F Blaabjerg