Optimizing daily operation of battery energy storage systems under real-time pricing schemes

Modernization of electricity networks is currently being carried out using the concept of the smart grid; hence, the active participation of end-user consumers and distributed generators will be allowed in order to increase system efficiency and renewable power accommodation. In this context, this paper proposes a comprehensive methodology to optimally control lead-acid batteries operating under dynamic pricing schemes in both independent and aggregated ways, taking into account the effects of the charge controller operation, the variable efficiency of the power converter, and the maximum capacity of the electricity network. A genetic algorithm is used to solve the optimization problem in which the daily net cost is minimized. The effectiveness and computational efficiency of the proposed methodology is illustrated using real data from the Spanish electricity market during 2014 and 2015 in order to evaluate the effects of forecasting error of energy prices, observing an important reduction in the estimated benefit as a result of both factors: 1) forecasting error and 2) power system limitations

Structural Evaluation for Distribution Networks with Distributed Generation Based on Complex Network

Structural analysis based on complex network theory has been considered promising for security issues of power grids. At the same time, modern power distribution networks with more Distributed Generations (DGs) and Energy Storage Systems (ESS) have taken on more challenges in operation and security issues. This paper proposed a dedicated metric named as Power-Supply-Ability for power distribution networks based on net-ability. Special features of DGs, such as relations of capacities, identification of effective supply area, and limitation in continuous power supply, have been considered in definition. Furthermore, a novel opinion is proposed that the extent of improvement for operation and security by adding DGs also depends on the original structure of the distribution networks. This is an inherent ability of the original networks and could be quantitatively analyzed. Through case studies, this method has been proved to be effective in identifying potential structural vulnerabilities of distribution networks; particularly the impact of DGs on security has been studied. Furthermore, it can help in site selection for DGs by providing different priorities of locations compared with results of other works. This can help to complement other methods to construct a more comprehensive methodology by considering aspects of security, economy, and quality

Optimal Management of an Integrated Electric Vehicle Charging Station under Weather Impacts

The focus of this Dissertation is on developing an optimal management of what is called the “Integrated Electric Vehicle Charging Station” (IEVCS) comprising the charging stations for the Plug-in Electric Vehicles (PEVs), renewable (solar) power generation resources, and fixed battery energy storage in the buildings. The reliability and availability of the electricity supply caused by severe weather elements are affecting utility customers with such integrated facilities. The proposed management approach allows such a facility to be coordinated to mitigate the potential impact of weather condition on customers electricity supply, and to provide warnings for the customers and utilities to prepare for the potential electricity supply loss. The risk assessment framework can be used to estimate and mitigate such impacts. With proper control of photovoltaic (PV) generation, PEVs with mobile battery storage and fixed energy storage, customers’ electricity demand could be potentially more flexible, since they can choose to charge the vehicles when the grid load demand is light, and stop charging or even supply energy back to the grid or buildings when the grid load demand is high. The PV generation capacity can be used to charge the PEVs, fixed battery energy storage system (BESS) or supply power to the grid. Such increased demand flexibility can enable the demand response providers with more options to respond to electricity price changes. The charging stations integration and interfacing can be optimized to minimize the operational cost or support several utility applications

Battery Energy Storage System Mitigation Strategies for the Grid Impacts of Electric Vehicle Charging Infrastructure

The face of transportation is changing as a greater number of companies and private individuals switch from traditional automobiles to electric vehicles. This surge has been bolstered by improvements in technology, increased marketing, and a heightened focus on the role humanity plays in climate change. This advancement brings a growth in electrical demand caused by the charging loads of these vehicles. Due to the quick, sudden rise of this technology, the utility energy industry is still in the early stages of preparing for electric vehicle loads beyond the traditional load growth. Though the technology for battery energy storage has been around for some time, there has been a recent resurgence of interest in using it at the grid level. Improvements in technology have made batteries cheaper and more efficient, while the interest in integrating more renewable energy sources has increased their production. With these improvements, battery energy storage may now be useful in mitigating the adverse effects of electric vehicle integration and improving the otherwise accelerated financial impact of these new charging loads. In this thesis, the grid impacts of electric vehicle growth and integration are observed on provided models of real-world feeders. Using this data, the effectiveness of battery energy storage systems in mitigating these impacts in a manner that is economical and beneficial to the utility, the customer, and the environment is analyzed. Following this, a general approach for analyzing electric vehicle impacts and potential mitigation strategies is presented

Smart Energy Management for Smart Grids

This book is a contribution from the authors, to share solutions for a better and sustainable power grid. Renewable energy, smart grid security and smart energy management are the main topics discussed in this book

Energy storage systems and grid code requirements for large-scale renewables integration in insular grids

This thesis addresses the topic of energy storage systems supporting increased penetration of renewables in insular systems. An overview of energy storage management, forecasting tools and demand side solutions is carried out, comparing the strategic utilization of storage and other competing strategies. Particular emphasis is given to energy storage systems on islands, as a new contribution to earlier studies, addressing their particular requirements, the most appropriate technologies and existing operating projects throughout the world. Several real-world case studies are presented and discussed in detail. Lead-acid battery design parameters are assessed for energy storage applications on insular grids, comparing different battery models. The wind curtailment mitigation effect by means of energy storage resources is also explored. Grid code requirements for large-scale integration of renewables are discussed in an island context, as another new contribution to earlier studies. The current trends on grid code formulation, towards an improved integration of distributed renewable resources in island systems, are addressed. Finally, modeling and control strategies with energy storage systems are addressed. An innovative energy management technique to be used in the day-ahead scheduling of insular systems with Vanadium Redox Flow battery is presented.Esta tese aborda a temática dos sistemas de armazenamento de energia visando o aumento da penetração de energias renováveis em sistemas insulares. Uma visão geral é apresentada acerca da gestão do armazenamento de energia, ferramentas de previsão e soluções do lado da procura de energia, comparando a utilização estratégica do armazenamento e outras estratégias concorrentes. É dada ênfase aos sistemas de armazenamento de energia em ilhas, como uma nova contribuição no estado da arte, abordando as suas necessidades específicas, as tecnologias mais adequadas e os projetos existentes e em funcionamento a nível mundial. Vários casos de estudos reais são apresentados e discutidos em detalhe. Parâmetros de projeto de baterias de chumbo-ácido são avaliados para aplicações de armazenamento de energia em redes insulares, comparando diferentes modelos de baterias. O efeito de redução do potencial de desperdício de energia do vento, recorrendo ao armazenamento de energia, também é perscrutado. As especificidades subjacentes aos códigos de rede para a integração em larga escala de energias renováveis são discutidas em contexto insular, sendo outra nova contribuição no estado da arte. As tendências atuais na elaboração de códigos de rede, no sentido de uma melhor integração da geração distribuída renovável em sistemas insulares, são abordadas. Finalmente, é estudada a modelação e as estratégias de controlo com sistemas de armazenamento de energia. Uma metodologia de gestão de energia inovadora é apresentada para a exploração de curto prazo de sistemas insulares com baterias de fluxo Vanádio Redox

Improving Grid Hosting Capacity and Inertia Response with High Penetration of Renewable Generation

To achieve a more sustainable supply of electricity, utilizing renewable energy resources is a promising solution. However, the inclusion of intermittent renewable energy resources in electric power systems, if not appropriately managed and controlled, will raise a new set of technical challenges in both voltage and frequency control and jeopardizes the reliability and stability of the power system, as one of the most critical infrastructures in the today’s world. This dissertation aims to answer how to achieve high penetration of renewable generations in the entire power system without jeopardizing its security and reliability. First, we tackle the data insufficiency in testing new methods and concepts in renewable generation integration and develop a toolkit to generate any number of synthetic power grids feathering the same properties of real power grids. Next, we focus on small-scale PV systems as the most growing renewable generation in distribution networks and develop a detailed impact assessment framework to examine its impacts on the system and provide installation scheme recommendations to improve the hosting capacity of PV systems in the distribution networks. Following, we examine smart homes with rooftop PV systems and propose a new demand side management algorithm to make the best use of distributed renewable energy. Finally, the findings in the aforementioned three parts have been incorporated to solve the challenge of inertia response and hosting capacity of renewables in transmission network

Grid-Scale Battery Storage for Variable Renewable Electricity in Sweden

This thesis explores how a market for grid-scale battery energy storage systems (BESS) can become reality in Sweden. Higher penetration levels of distributed, variable renewable energy (VRE) from wind power challenge the incumbent energy regime and require new solutions for the grid integration of renewables. As a consequence, a more flexible power system is needed in order to deal with the induced supply-side variability. Batteries, as one flexibility solution among several other options, have shown promising technological development and are a versatile electricity storage option. BESS can provide multiple benefits for different application areas on the grid at various scales. The emergence of grid-scale BESS in Sweden was analysed using the multi-level perspective (MLP) framework on socio-technical transitions. Despite the great potential and the rapid technological progress of BESS, it was found that regulatory factors, both in Sweden and the EU, currently constitute a major barrier for the deployment of large-scale electricity storage. Moreover, Sweden looks set to continue to increase the uptake of VRE from wind power, whilst a gradual phase out of nuclear power over the next decades is also likely. Whereas this would normally have negative implications for the power system, the ample hydropower capacity and sufficient interconnection to the neighbouring Nordic countries provide, at least for the near future, enough system flexibility and therefore reducing the need for the installation of BESS. However, the uneven geographic distribution of electricity consumption and generation across Sweden might give rise to flexibility solutions for enhancing local distribution networks in the future in order to eliminate potential regional bottlenecks

Impact Analysis and Mitigation of Voltage Regulation Issues in PV Rich Low Voltage Residential Distribution Networks

Modern distribution networks are undergoing major changes with the increased uptake of rooftop photovoltaic (PV) units in low voltage (LV) residential distribution networks. These renewable based distributed energy resources (DERs) impose adverse effects which can propagate from LV to medium voltage (MV) and high voltage (HV) levels. Some of the major areas of concern to network operators include reverse power flow, voltage unbalance, voltage rise, increased harmonics, increased potential of islanding, and component and line overloading. These issues create both an operational mitigation requirement and a need for Distribution Network Service Providers (DNSPs) to adjust LV network design procedures. In Australia DNSPs are bound by strict regulation to provide supply to customers complying with several power quality standards. Australian Standard AS 61000.3.100 requires the voltage at the consumer point of supply to be within +10%, -6% of the 230 V nominal for single phase LV customers. Since residential peak load is typically observed during evening time and power generated from PV during daytime, rooftop PV does little to reduce peak demand. Increased numbers of rooftop PV systems in future LV feeders, combined with increased demand, means DNSPs need to invest in infrastructure to alleviate issues related to overgeneration or overloading and voltage regulation. Traditionally, voltage regulation devices such as on-load tap changers (OLTCs), regulators and capacitor banks have been sufficient to regulate voltage within mandated limits. Bidirectional power flow that arises as a result of DER in LV limits the ability of these devices, as LV voltage issues cannot be detected or do not propagate further up the network. Compared to HV/MV networks, residential LV networks experience more variable loads, have inherent unbalance due to the overhead 4-wire structure, and lack visibility with respect to operational states. This thesis aims to contribute new knowledge and understanding to the field of power distribution network voltage regulation. This includes investigation and analysis of different approaches to voltage regulation in power distribution networks in the literature, and to propose new methods and improvements to existing methods. Specifically, this thesis aims to highlight the shortcomings of the current voltage regulation techniques available to DNSPs in LV feeder. The case studies to be provided in this thesis presents 24 h time series simulation to investigate the performance with varying load and PV generation