Optimum Resilient Operation and Control DC Microgrid Based Electric Vehicles Charging Station Powered by Renewable Energy Sources

This paper introduces an energy management and control method for DC microgrid supplying electric vehicles (EV) charging station. An Energy Management System (EMS) is developed to manage and control power flow from renewable energy sources to EVs through DC microgrid. An integrated approach for controlling DC microgrid based charging station powered by intermittent renewable energies. A wind turbine (WT) and solar photovoltaic (PV) arrays are integrated into the studied DC microgrid to replace energy from fossil fuel and decrease pollution from carbon emissions. Due to the intermittency of solar and wind generation, the output powers of PV and WT are not guaranteed. For this reason, the capacities of WT, solar PV panels, and the battery system are considered decision parameters to be optimized. The optimized design of the renewable energy system is done to ensure sufficient electricity supply to the EV charging station. Moreover, various renewable energy technologies for supplying EV charging stations to improve their performance are investigated. To evaluate the performance of the used control strategies, simulation is carried out in MATLAB/SIMULINK. Document type: Articl

Power management and control strategies for efficient operation of a solar power dominated hybrid DC microgrid for remote power applications

In this paper, a hybrid DC microgrid consisting of a diesel generator with a rectifier, a solar photovoltaic (PV) system, and a battery energy storage system is presented in relation to an effective power management strategy and different control techniques are adopted to power electronic interfaces. The solar PV and battery energy storage systems are considered as the main sources of energy sources that supply the load demand on a daily basis whereas the diesel generator is used as a backup for the emergency operation of the microgrid. All system components are connected to a common DC bus through an appropriate power electronics devices (e.g., rectifier systems, DC/DC converter). Also a detailed sizing philosophy of all components along with the energy management strategy is proposed. Energy distribution pattern of each individual component has been conducted based on the monthly basis along with a power management algorithm. The power delivered by the solar PV system and diesel generator is controlled via DC-DC converterand excitation controllers which are designed based on a linearquadratic regulator (LQR) technique as as proportional integral (PI)controllers. The component level power distribution is investigatedusing these controllers under fluctuating load and solar irradiationconditions and comparative results are presented

Bidirectional three port converter for power flow management of PV/Battery-Fed elevator system

The Bidirectional Three Port Converter (BTPC) proposed in this research work is addressed for an elevator application that is driven from a BLDC motor in all four quadrants sourced from solar Photovoltaic (PV). The converter design of a PV based system necessitates constant output voltage with high power density and efficiency. The Proposed BTPC tracks the maximum power, maintains constant output voltage and also deals with the bidirectional power flow management whenever there is a change in applied torque when the machine is switched from motoring to regenerating mode. Furthermore, single stage power conversion is achieved with power transfer from PV to dc link or battery to dc link based on the load requirement and surplus power is directly stored in the battery. Closed loop control ensures adjusting the duty cycle of the proposed converter switches thereby maintaining the bidirectional power flow management. The proposed converter is analysed in detail with operating principle, design considerations and verified in terms of simulation and through experimental results

An Energy Management System-Based Control Strategy for DC Microgrids with Dual Energy Storage Systems

In this work, a control strategy is developed for different components in DC microgrids where set points for all controllers are determined from an energy management system (EMS). The proposed EMS-based control scheme is developed for DC microgrids with solar photovoltaic (PV) systems as the primary generation units along with energy storage systems. In this work, the concept of dual energy storage systems (DESSs) is used, which includes a battery energy storage system (BESS) and supercapacitor (SC). The main feature of this DESS is to improve the dynamic performance of DC microgrids during severe transients appearing from changes in load demands as well as in the output power from solar PV units. Furthermore, the proposed EMS-based control scheme aims to enhance the lifetime of the BESS in DC microgrids with DESSs and voltage stability as compared to the same without SCs. The proposed EMS-based control strategy uses proportional-integral (PI) controllers to regulate the switching control actions for different converters within the DC microgrid based on the decision obtained from the EMS in order to achieve the desired control objectives. The performance of the proposed scheme was analyzed through simulation results in terms of improving the voltage stability, maintaining the power balance, and enhancing the lifetime of BESSs within a DC microgrid framework incorporated with the DESS. The simulations are carried out in the MATLAB/SIMULINK simulation platform and compared with a similar approach having only a single energy storage system, i.e., the BESS

New Topologies and Advanced Control of Power Electronic Converters for Renewable Energy based Microgrids

Solar energy-based microgrids are increasingly promising due to their many features, such as being environmentally friendly and having low operating costs. Power electronic converters, filters, and transformers are the key components to integrate the solar photovoltaic (PV) systems with the microgrids. The power electronic converters play an important role to reduce the size of the filter circuit and eliminate the use of the bulky and heavy traditional power frequency step-up transformer. These power converters also play a vital role to integrate the energy storage systems such as batteries and the superconducting magnetic energy storage (SMES) unit in a solar PV power-based microgrid. However, the performance of these power converters depends upon the switching technique and the power converter configuration. The switching techniques can improve the power quality, i.e. lower total harmonic distortion at the converter output waveform, reduce the converter power loss, and can effectively utilize the dc bus voltage, which helps to improve the power conversion efficiency of the power electronic converter. The power converter configuration can reduce the size of the power converter and make the power conversion system more efficient. In addition to the advanced switching technique, a supervisory control can also be integrated with these power converters to ensure the optimal power flow within the microgrid. First, this thesis reviews different existing power converter topologies with their switching techniques and control strategies for the grid integration of solar PV systems. To eliminate the use of the bulky and heavy line frequency step-up transformer to integrate solar PV systems to medium voltage grids, the high frequency magnetic linkbased medium voltage power converter topologies are discussed and compared based on their performance parameters. Moreover, switching and conduction losses are calculated to compare the performance of the switching techniques for the magnetic-linked power converter topologies. In this thesis, a new pulse width modulation technique has been proposed to integrate the SMES system with the solar PV system-based microgrid. The pulse width modulation technique is designed to provide reactive power into the network in an effective way. The modulation technique ensures lower total harmonic distortion (THD), lower switching loss, and better utilization of dc-bus voltage. The simulation and experimental results show the effectiveness of the proposed pulse width modulation technique. In this thesis, an improved version of the previously proposed switching technique has been designed for a transformer-less PV inverter. The improved switching technique can ensure effective active power flow into the network. A new switching scheme has been proposed for reactive power control to avoid unnecessary switching faced by the traditional switching technique in a transformer-less PV inverter. The proposed switching technique is based on the peak point value of the grid current and ensures lower switching loss compared to other switching techniques. In this thesis, a new magnetic-linked multilevel inverter has been designed to overcome the issues faced by the two-level inverters and traditional multilevel inverters. The proposed multilevel inverter utilizes the same number of electronic switches but fewer capacitors compared to the traditional multilevel inverters. The proposed multilevel inverter solves the capacitor voltage balancing and utilizes 25% more of the dc bus voltage compared to the traditional multilevel inverter, which reduces the power rating of the dc power source components and also extends the input voltage operating range of the inverter. An improved version magnetic-linked multilevel inverter is proposed in this thesis with a model predictive control technique. This multilevel inverter reduces both the number of switches and capacitors compared to the traditional multilevel inverter. This multilevel inverter also solves the capacitor voltage balancing issue and utilizes 50% more of the dc bus voltage compared to the traditional multilevel inverter. Finally, an energy management system has been designed for the developed power converter and control to achieve energy resiliency and minimum operating cost of the microgrid. The model predictive control-based energy management system utilizes the predicted load data, PV insolation data from web service, electricity price data, and battery state of charge data to select the battery charging and discharging pattern over the day. This model predictive control-based supervisory control with the advanced power electronic converter and control makes the PV energy-based microgrid more efficient and reliable

New and improved solutions for the configuration, management and operation of large-scale photovoltaic power plants using hybrid energy storage system

This thesis is presented in the context of multiple efforts being made by research groups in order to disseminate and evolve the technological knowledge in the renewable energy (RE) field. The motivation of this study is based on the main disadvantages of photovoltaic (PV) solar power generation compared to conventional energy sources, such as intermittency, non-dispatchability, and unreliability. From those drawbacks, the aim is to find creative solutions to mitigate these issues with a power plant combining PV and hybrid energy storage systems (HESS). In doing so, hybrid power plants represent a very interesting option for power generation and grid integration of PV systems, since they allow increased efficiency in the energy generation, as well as storing and supporting RE generation when needed.The storage systems are particularly important to deal with the intermittent nature of solar radiation. A wide variety of storage systems exists nowadays, all of them based on different operating principles and target applications. A thorough review of the literature has exposed that, depending on the application, a certain type of storage could be preferred above others. Besides, two or more different technologies working together can present complementary features. In this sense, the HESS can accomplish higher efficiencies and improved systems for grid connection. The objective is to develop new solutions to improve the configuration, management, and operation of PV plants with energy storage, designing the necessary control techniques and validating them through real-time simulations. In this context, this thesis presents a large-scale PV power plant with HESS, through a DC/DC impedance source converter (DC/DC-ZSC), and a new simplified model (SM) of the quasi Z-source inverter with battery energy storage (qZSI-BES) attached directly to the Z-network without an extra DC/DC converter. The HESS consists of battery arrays (BES) and ultracapacitors (UC). The newly designed SM is implemented, assessed, and validated experimentally in laboratory through a TYPHOON HIL system and a dSPACE MicroLabBox control board. Three different energy management strategies are implemented, using two of them advanced control techniques based on fuzzy logic. The control loops of the active, reactive, BES, and UC power have been conveniently deployed. The results obtained are coherent with the expected responses, observing an appropriate power balance and grid energy dispatch. This thesis aims for a relevant contribution in the development of low polluting energy sources that can fulfill the growing electricity demand. Following the global trends, and recognizing the importance of this knowledge for the scientific community and for society, this thesis will provide new solutions in the field of solar PV generation. In view of the fact that research has mainly focused on small-scale hybrid power plants so far, further studies are required regarding the configuration, design, control, energy management, operation, and problems associated with large PV power plants with hybrid storage

Solar energy management system with supercapacitors for rural application

Growing energy demands are expected to exceed the supply from current energy resources. Therefore, renewable energy and energy management systems will become more crucial for increasing supply and efficiency of energy usage. The novelty of this research is an energy management system (EMS) based on fuzzy logic for a solar house to ensure the maximum utilisation of renewable sources, protect components from being damaged due to overloading, and manage energy storage devices to increase stability in the power system. There is no published analysis of hybrid energy storage between battery and supercapacitor using fuzzy logic as EMS. The energy management system is implemented in a solar cabin system developed by IBC Solar to mimic a typical rural house. The solar cabin is equipped with solar photovoltaic panels, solar charger, battery and inverter. Supercapacitors and a custom made DC to DC converter were added to the system to support the batteries during high current load demand and manage energy flow. Three sets of experiments were conducted in the solar cabin system with the new energy management system. Power consumption usage of a typical rural household was studied to create two load profiles that were used as load for the experiments. The results show an efficiency of 95.9% by using the new energy management system and supercapacitors to the solar cabin, which is higher than recent research (95.2% and 84.4%). The result is on par with the Malaysian and International Standard in energy efficiency of around 95%. The energy management system controlled the charging and discharging of the battery and supercapacitor using fuzzy logic. The novelty of this thesis is use of supercapacitors to reduce stress on the battery and an energy management system to control and manage the system for efficient energy usage

Power Quality Enhancement in Hybrid Photovoltaic-Battery System based on three–Level Inverter associated with DC bus Voltage Control

This modest paper presents a study on the energy quality produced by a hybrid system consisting of a Photovoltaic (PV) power source connected to a battery. A three-level inverter was used in the system studied for the purpose of improving the quality of energy injected into the grid and decreasing the Total Harmonic Distortion (THD). A Maximum Power Point Tracking (MPPT) algorithm based on a Fuzzy Logic Controller (FLC) is used for the purpose of ensuring optimal production of photovoltaic energy. In addition, another FLC controller is used to ensure DC bus stabilization. The considered system was implemented in the Matlab /SimPowerSystems environment. The results show the effectiveness of the proposed inverter at three levels in improving the quality of energy injected from the system into the grid.Peer reviewedFinal Published versio