ANALYSIS AND SIMULATION OF PHOTOVOLTAIC SYSTEMS INCORPORATING BATTERY ENERGY STORAGE

Solar energy is an abundant renewable source, which is expected to play an increasing role in the grid\u27s future infrastructure for distributed generation. The research described in the thesis focuses on the analysis of integrating multi-megawatt photovoltaics (PV) systems with battery energy storage into the existing grid and on the theory supporting the electrical operation of components and systems. The PV system is divided into several sections, each having its own DC-DC converter for maximum power point tracking and a two-level grid connected inverter with different control strategies. The functions of the battery are explored by connecting it to the system in order to prevent possible voltage fluctuations and as a buffer storage in order to eliminate the power mismatch between PV array generation and load demand. Computer models of the system are developed and implemented using the PSCADTM/EMTDCTM software

Multi-function power electronic interface for hybrid mini-grid systems

In the past five years, global interest regarding the development of renewable energy technologies has significantly increased. The conventional electric power generation methods sourced from fossil fuels is now problematic, from both the supply and emission points of view. Fossil fuels are non-renewable limited resources that have taken millions of years to form; eventually they will be exhausted and the current cost of automotive fuel is evidence of them becoming diminished. The carbon dioxide emissions created through the energy conversion process are causing an increase in the overall atmospheric concentrations, which through global warming may have serious consequences for humanity.Natural sources of energy production can be derived from the Sun through the use of solar and wind generation methods. Converting these sources to electricity requires the technology of power electronics, the central area of research for this dissertation. Solar energy can most easily be harnessed through the photo-electric effect which creates DC electricity. However, the majority of electric loads and transmission require AC electricity. The inverter is the electronic device required for this power conversion. Wind turbines usually create variable voltage and frequency AC that is rectified to DC and then converted to grid type AC through an inverter.Voltage source inverters, their topologies and control are investigated within this dissertation. Voltage control methods are adopted for both stand-alone and grid connected techniques where control of active and reactive power is required. Current control techniques in the form of PI and hysteresis are applied to allow novel interfaces between generation sources to be achieved. Accurate control of the power electronics allows an enhancement in the power production from the renewable energy source. The power electronic device of the DC-DC converter, either buck or boost is controlled to allow the renewable resource to operate at its optimum power point. The control aspects and algorithms of these converters are central to this research. The solar algorithms of perturb and observe, and incremental conductance are developed with the latter being more favourable to changing levels of irradiation. The author draws a parallel between rapidly changing solar conditions with normally changing wind states. This analogy with an understanding of the mechanics of PMSG allows a novel wind MPPT algorithm to be developed which is simulated in PSIM. Methods to analyse the usefulness of the algorithm are developed and general conclusions are drawn.Another aim central to the research is the efficient combination of renewable energy sources into a single reliable power system. This forms the multi-function aspect of the research. The interconnection of the sources on the AC or DC sides is investigated for both stand-alone and grid connected topologies. A requirement of the stand-alone system is to provide power when no renewable resources are available causing some form of energy storage to be utilised. Conventional batteries are used, causing the VC-VSI to become bi-directional allowing charging. This is simulated in PSIM and demonstrated as part of the Denmark and Eco Beach projects. Many differing topologies of stand alone, grid connected and edge of grid systems are developed, simulated and some are demonstrated.While investigating the currently used topologies the author invents the novel complimentary hybrid system concept. This idea allows a single inverter to be used to feed energy from either the wind or solar resource. With careful engineering of the PV array and wind turbine characteristics only a small loss of energy is caused, deemed the crossover loss. This original concept is mathematically modelled, simulated and demonstrated with results presented from the Denmark project. The strength of this idea is from the quite complimentary nature of wind and solar resources, for only a small proportion of the year are high solar and strong wind conditions occurring simultaneously.Compared to a solar resource, the wind resource is much more complicated to model. An analysis of readily available wind source data is presented with a statistical analysis of the scaling methods; a novel box and whiskers plot is used to convey this information. New software is presented to allow a more accurate and digital model of a power curve to be recreated, allowing a more precise annual energy generation calculation. For various wind turbines a capacity factor analysis is presented with its disadvantages explained. To overcome these issues the concepts of economic efficiency and conversion efficiency are explained. These prevent some of the typical methods to enhance the standard capacity factor expression. The combination of these three methods allows selection of the most suitable wind turbine for a site.The concept of a mini-grid is an isolated power generation and distribution system, which can have its renewable energy sources, centralised or decentralised. The methods used to coalesce conventional generation with renewable energy technology forms another key piece of this research. A design methodology for the development of a hybrid power system is created with examples used from projects attributed to the author. The harmonising of the renewable energy sources with the conventional generation while providing a stable and robust grid is explained in detail with respect to the generator loading and control. The careful control of the renewable resource output is shown to allow a greater overall penetration of renewable energy into the network while continuing network stability. The concept of frequency shift control is presented, simulated and demonstrated with reference to the Eco Beach project. This project epitomises much of the research that has been presented in this dissertation. It combines centralised and decentralised inverters, with battery storage and the control of diesel generators. An overall controller dictates the optimum times to charge or draw from the battery based upon the local environmental and time of day variables. Finally, the monitoring aspects of this project are representative of a future smart grid where loads may be shed on demand through under frequency or direct control

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Design description of the Schuchuli Village photovoltaic power system

A stand alone photovoltaic (PV) power system for the village of Schuchuli (Gunsight), Arizona, on the Papago Indian Reservation is a limited energy, all 120 V (d.c.) system to which loads cannot be arbitrarily added and consists of a 3.5 kW (peak) PV array, 2380 ampere-hours of battery storage, an electrical equipment building, a 120 V (d.c.) electrical distribution network, and equipment and automatic controls to provide control power for pumping water into an existing water system; operating 15 refrigerators, a clothes washing machine, a sewing machine, and lights for each of the homes and communal buildings. A solar hot water heater supplies hot water for the washing machine and communal laundry. Automatic control systems provide voltage control by limiting the number of PV strings supplying power during system operation and battery charging, and load management for operating high priority at the expense of low priority loads as the main battery becomes depleted

A SRM for a PV Powered Water Pumping System Based on a Multilevel Converter and DC/DC Dual Output Converter

Trabalho apresentado em 7th International Conference on Smart and Sustainable Technologies - Splitech 2022, 5-8 julho 2022, Bol, CroatiaThis paper focuses on a proposal for a system based on a photovoltaic (PV) supply for a powered water pumping. The system consists in a switched reluctance machine (SRM) controlled by a multilevel converter and fed by PV panels associated to a DC/DC converter. The multilevel power converter proposed to control the SRM was designed to minimize the switches and to support the balance of the two input capacitors. The DC/DC converter consists in a hybrid solution that merges a Buck- Boost converter with a Sepic converter. They use a topology solution in which the input current presents a reduced ripple and only requires one switch. This DC/DC converter is also characterized by a dual output to adapt to the multilevel converter. The control system and a maximum power point tracking (MPPT) algorithm are also presented. The operation of this system will be verified by tests that are done by computer simulations.N/

A SRM for a PV powered water pumping system based on a multilevel converter and DC/DC dual output converter

This paper focuses on a proposal for a system based on a photovoltaic (PV) supply for a powered water pumping. The system consists in a switched reluctance machine (SRM) controlled by a multilevel converter and fed by PV panels associated to a DC/DC converter. The multilevel power converter proposed to control the SRM was designed to minimize the switches and to support the balance of the two input capacitors. The DC/DC converter consists in a hybrid solution that merges a Buck-Boost converter with a Sepic converter. They use a topology solution in which the input current presents a reduced ripple and only requires one switch. This DC/DC converter is also characterized by a dual output to adapt to the multilevel converter. The control system and a maximum power point tracking (MPPT) algorithm are also presented. The operation of this system will be verified by tests that are done by computer simulations.info:eu-repo/semantics/publishedVersio

Control of Solar Photovoltaic (PhV) Power Generation In Grid-connected and Islanded Microgrids

With the ever increasing electricity demand, fast depletion of fossil fuel and the growing trend towards renewable energy resources, the integration of green distributed energy resources (DERs) such as solar photovoltaic (PhV) generation and wind power in the utility grid is gaining high popularity in the present years. The capability of these modular generators needs to be harnessed properly in order to achieve the maximum benefit out of such integrated systems. Most DERs are connected to the utility grid or microgrids with the help of power electronics interface. They are capable of producing both active and reactive power with the proper control of the inverter interface. This dissertation focuses on examination of the capability of the renewable energy based DERs, such as solar PhV array and battery energy storage system (BESS) in providing voltage support in grid connected low-voltage microgrids and both voltage and frequency support in islanded microgrids. In addition, active and reactive (a.k.a. nonactive) power control capability of the PhV generators to supply the local loads assigned by the microgrid central operator in grid connected mode is also investigated. The control methods are developed by using a Proportional and Integral (PI) controller. A new method of Maximum Power Point Tracking (MPPT) of solar array including the MPPT at solar PhV array side and a new control method of transferring this MPP power to the inverter side insuring the DC voltage stability by using the concept of power balance at various conversion stages is proposed and studied. The dissertation also proposes a new coordinated control method for voltage and frequency regulation of microgrid with solar PhV generator operating at MPP and backed up by battery energy storage systems. A coordinated active and reactive power control for solar PhV generator with MPPT control and battery storage is also proposed and investigated. Various case studies are presented to validate the proposed methods. The simulation results clearly prove the effectiveness of the proposed control method

Technology for large space systems: A special bibliography with indexes (supplement 03)

A bibliography containing 217 abstracts addressing the technology for large space systems is presented. State of the art and advanced concepts concerning interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments are represented