Power management and control for solar-wind-diesel stand-alone hybrid energy systems

xiv, 88 leaves : ill. ; 29 cm.Includes abstract and appendix.Includes bibliographical references (leaves 81-86).A simulation based research on developing a power management and control system for stand-alone solar-wind-diesel hybrid energy systems is presented in this dissertation. The simulation model of stand-alone system is developed from mathematical models of solar photovoltaic system, wind turbines and diesel generators. A multi-variable control system is developed and implemented into the simulation models in order to achieve optimum performance. The model of solar photovoltaic energy conversion system is constructed with maximum power point tracking control to extract maximum power from the solar photovoltaic system. An improved control system is developed for wind energy conversion system to optimize the operation of wind turbine through speed regulation and maximum power point tracking control. In addition, a governor control system is developed for the diesel generation system. The frequency regulation system consist conventional phase locked loop system and a voltage regulator in order to regulate the load voltage. A power management strategy is introduced to share the generated power and to improve the power quality where priority is given to the wind energy conversion system. The power management algorithm controls the sharing of generated power and optimizes the hybrid operation. The complete model of stand-alone solar-wind-diesel hybrid energy system is simulated in Matlab®/Simulink® interface. Results obtained from the simulation are presented to validate the control algorithms developed in this work

Wind Technology: A Framework for the Evaluation of Innovations’ Impacts on the Diffusion Potential

This paper proposes a framework based on which innovations in wind power technologies can be evaluated from the standpoint of their contribution to diffusion expansion. The framework helps build up a missing link between the technical literature on innovations and policy-oriented contributions concerned with the diffusion potential of wind power in national energy systems. The ideas are applied for the evaluation of wind technology innovations adopted in Spain. The framework can help policy-makers prioritize their innovation objectives and funding, so as to support the adoption of innovations that deserve the highest priority, given the country’s resources and energy system characteristics

Battery sizing for a stand alone passive wind system using statistical techniques

In this paper, an original optimization method to jointly determine a reduced study term and an optimum battery sizing is investigated. This storage device is used to connect a passive wind turbine system with a stand alone network. A Weibull probability density function is used to generate different wind speed data. The passive wind system is composed of a wind turbine, a permanent magnet synchronous generator feeding a diode rectifier associated with a very low voltage DC battery bus. This study is essentially based on a similitude model applied on an 8 kW wind turbine system. Our reference model is taken from a 1.7 kW optimized system. The wind system generated power and the load demand are coupled through a battery sized using a statistical approach

Solar Photovoltaic and Thermal Energy Systems: Current Technology and Future Trends

Solar systems have become very competitive solutions for residential, commercial, and industrial applications for both standalone and grid connected operations. This paper presents an overview of the current status and future perspectives of solar energy (mainly photovoltaic) technology and the required conversion systems. The focus in the paper is put on the current technology, installations challenges, and future expectations. Various aspects related to the global solar market, the photovoltaic (PV) modules cost and technology, and the power electronics converter systems are addressed. Research trends and recommendations for each of the PV system sectors are also discussed.Junta de Andalucía P11-TIC-7070Ministerio de Ciencia e Innovación TEC2016-78430-

Power Quality Enhancement in Electricity Grids with Wind Energy Using Multicell Converters and Energy Storage

In recent years, the wind power industry is experiencing a rapid growth and more wind farms with larger size wind turbines are being connected to the power system. While this contributes to the overall security of electricity supply, large-scale deployment of wind energy into the grid also presents many technical challenges. Most of these challenges are one way or another, related to the variability and intermittent nature of wind and affect the power quality of the distribution grid. Power quality relates to factors that cause variations in the voltage level and frequency as well as distortion in the voltage and current waveforms due to wind variability which produces both harmonics and inter-harmonics. The main motivation behind work is to propose a new topology of the static AC/DC/AC multicell converter to improve the power quality in grid-connected wind energy conversion systems. Serial switching cells have the ability to achieve a high power with lower-size components and improve the voltage waveforms at the input and output of the converter by increasing the number of cells. Furthermore, a battery energy storage system is included and a power management strategy is designed to ensure the continuity of power supply and consequently the autonomy of the proposed system. The simulation results are presented for a 149.2 kW wind turbine induction generator system and the results obtained demonstrate the reduced harmonics, improved transient response, and reference tracking of the voltage output of the wind energy conversion system.Peer reviewedFinal Accepted Versio

Hydrogen vs. Battery in the long-term operation. A comparative between energy management strategies for hybrid renewable microgrids

The growth of the world’s energy demand over recent decades in relation to energy intensity and demography is clear. At the same time, the use of renewable energy sources is pursued to address decarbonization targets, but the stochasticity of renewable energy systems produces an increasing need for management systems to supply such energy volume while guaranteeing, at the same time, the security and reliability of the microgrids. Locally distributed energy storage systems (ESS) may provide the capacity to temporarily decouple production and demand. In this sense, the most implemented ESS in local energy districts are small–medium-scale electrochemical batteries. However, hydrogen systems are viable for storing larger energy quantities thanks to its intrinsic high mass-energy density. To match generation, demand and storage, energy management systems (EMSs) become crucial. This paper compares two strategies for an energy management system based on hydrogen-priority vs. battery-priority for the operation of a hybrid renewable microgrid. The overall performance of the two mentioned strategies is compared in the long-term operation via a set of evaluation parameters defined by the unmet load, storage efficiency, operating hours and cumulative energy. The results show that the hydrogen-priority strategy allows the microgrid to be led towards island operation because it saves a higher amount of energy, while the battery-priority strategy reduces the energy efficiency in the storage round trip. The main contribution of this work lies in the demonstration that conventional EMS for microgrids’ operation based on battery-priority strategy should turn into hydrogen-priority to keep the reliability and independence of the microgrid in the long-term operation

Analysis of the economic feasibility and reduction of a building’s energy consumption and emissions when integrating hybrid solar thermal/PV/micro-CHP systems

The aim of this paper is to assess the performance of several designs of hybrid systems composed of solar thermal collectors, photovoltaic panels and natural gas internal combustion engines. The software TRNSYS 17 has been used to perform all the calculations and data processing, as well as an optimisation of the tank volumes through an add-in coupled with the GENOPT® software. The study is carried out by analysing the behaviour of the designed systems and the conventional case in five different locations of Spain with diverse climatic characteristics, evaluating the same building in all cases. Regulators, manufacturers and energy service engineers are the most interested in these results. Two major contributions in this paper are the calculations of primary energy consumption and emissions and the inclusion of a Life Cycle Cost analysis. A table which shows the order of preference regarding those criteria for each considered case study is also included. This was fulfilled in the interest of comparing between the different configurations and climatic zones so as to obtain conclusions on each of them. The study also illustrates a sensibility analysis regarding energy prices. Finally, the exhaustive literature review, the novel electricity consumption profile of the building and the illustration of the influence of the cogeneration engine working hours are also valuable outputs of this paper, developed in order to address the knowledge gap and the ongoing challenges in the field of distributed generation

Storage Size Determination for Grid-Connected Photovoltaic Systems

In this paper, we study the problem of determining the size of battery storage used in grid-connected photovoltaic (PV) systems. In our setting, electricity is generated from PV and is used to supply the demand from loads. Excess electricity generated from the PV can be stored in a battery to be used later on, and electricity must be purchased from the electric grid if the PV generation and battery discharging cannot meet the demand. Due to the time-of-use electricity pricing, electricity can also be purchased from the grid when the price is low, and be sold back to the grid when the price is high. The objective is to minimize the cost associated with purchasing from (or selling back to) the electric grid and the battery capacity loss while at the same time satisfying the load and reducing the peak electricity purchase from the grid. Essentially, the objective function depends on the chosen battery size. We want to find a unique critical value (denoted as $C_{ref}^c$) of the battery size such that the total cost remains the same if the battery size is larger than or equal to $C_{ref}^c$, and the cost is strictly larger if the battery size is smaller than $C_{ref}^c$. We obtain a criterion for evaluating the economic value of batteries compared to purchasing electricity from the grid, propose lower and upper bounds on $C_{ref}^c$, and introduce an efficient algorithm for calculating its value; these results are validated via simulations.Comment: Submitted to IEEE Transactions on Sustainable Energy, June 2011; Jan 2012 (revision

Small-scale (≤6 kWe) stand-alone and grid-connected photovoltaic, wind, hydroelectric, biodiesel, and wood gasification system's simulated technical, economic, and mitigation analyses for rural regions in Western Australia

This research develops models and simulations of technical performance, net emission reductions, and discounted market values of thirteen small-scale (≤6 kWe) renewable energy projects. The research uses a simple methodology suitable for small private entities and governments to compare alternative investment options for both climate change mitigation and adaptation in the southwest of Western Australia. The system simulation and modelling results indicate that privately-owned, small-scale, grid-connected renewable energy systems were not competitive options for private entities relative to sourcing electricity from electricity networks, despite subsidies. The total discounted capital and operating costs, combined with the minimal mitigation potentials of the small-scale renewable energy systems resulted in unnecessarily high electricity costs and equivalent carbon prices, relative to grid-connection and large-scale clean energy systems. In contrast, this research suggests that small-scale renewable energy systems are cost-effective for both private entities and governments and exhibit good mitigation potentials when installed in remote locations far from the electricity network, mostly displacing diesel capacity