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In present day scenario, the focus is reallocating towards integration of small and medium scale power plants based on renewable energy sources into the power distribution system. Solar is the fastest growing form of renewable energy and a single phase voltage source inverter is used to interface photovoltaic based plants with the distribution system. The grid integrated inverter has stringent control requirements. A current controller is employed to mitigate the harmonics in the current injected into the grid and regulate the power exchange between the plant and the grid. This paper presents a review of the current control strategies implemented for a single phase grid tied photovoltaic inverter. A comparative performance evaluation of the current control techniques is also presented through simulation and experimental results. [ABSTRACT FROM AUTHOR]

The evolution of existing electricity grids to smart grids is aimed at accommodating increasing shares of renewable generation thus contributing for the de-carbonization of economy, offering more diversified services to consumers, enhancing different types of markets (energy, capacity, ancillary services) and improving the system's overall efficiency. As the economic characteristics of the electricity sector tend to discourage investments in smart grids, many countries have adopted incentive policies to foster the deployment of new technologies, which vary according to the particular characteristics of each country. Therefore, the design of specific public policies for Brazil must consider not only the motivations involved, but also the existing challenges for the implementation of smart grids and the socio-economic context. Moreover, the relevance of the proposed policies can be seen from different perspectives. This justifies the need to elicit information from multiple stakeholders for decision support purposes. This paper presents and assesses a set of policies identified by different stakeholders as having a potential to foster the development of smart grids in Brazil. The methodology to shape this set of policies consisted of a thorough literature review of international experiences, combined with meetings with experts in several domains. Then, these policies were assessed by applying a Delphi questionnaire aiming at measuring their effectiveness in fulfilling the objectives associated with investments in smart grids. A first conclusion is that all policies were assessed as having a positive impact taking into account each of the objectives, differing only in the priority to be assigned to each one. The policies that were considered more relevant were: "Incentive Policies for Promoting Demand-Side Management, Distributed Generation and Storage", "Regulatory Changes to Foster Innovation in the Energy Sector" and "Regulation of New Business Models". Among the policies with the worst scores, "Mandatory Rollout of Smart Meters" and "Establishing Quality Standards for the Telecommunications Industry" were ranked as the two lower-ranked policies, i.e., they were assigned lower priority under all objectives. [ABSTRACT FROM AUTHOR]

Recent improvements in computer processing power have enabled the development of intelligent electronic devices (IEDs) to be capable of interpreting a substantial quantity of data at high speeds. The distribution industry is one of the largest users of real-time data during the operation of their energy distribution network and as such, has an inherent need for data processing technology. The development of intelligent devices and communication protocols has given rise to the concept of distribution system automation (DSA). In this paper the major features of DSA development are discussed. A method of communication along with the integration of wired and wireless communication solutions with IED and Mote technology is described. Protection scheme automation is investigated, showing that automated response to network fault conditions is possible. Network reconfiguration is another key aspect of DSA research and two distinct calculation techniques are discussed. The current index (CI) and the load balance index (LBI) calculation methods are presented and the benefits of LBI are highlighted. Distributed generation (DG) is addressed in the context of automation with a demand side management (DSM) program proposed to manage load during peak and off-peak periods. The paper discusses switching DG sources, load deferral strategies and direct load control to effect a reduction in load during peak periods. The paper furthers this load management by load filling during off-peak periods. Finally, conclusions on the effectiveness of the proposed method are drawn and recommendations are made for further research. [ABSTRACT FROM AUTHOR]

DC microgrids have recently attracted research interest. A DC microgrid is composed of different dispatchable and non-dispatchable power generators and energy buffers, such as fuel cells and ultracapacitors, which are employed to provide the steady-state and transient power demanded by the load. To interface these generation resources to a common DC bus-bar, different configurations of power electronic converters have been proposed in the literature. For the fuel cell, a unidirectional DC–DC converter is utilised, for the ultracapacitor, however, a bidirectional DC–DC converter is needed to maintain the state-of-the-charge of the ultracapacitor. The overall efficiency of the microgrid will depend on the efficiency of these converters. High efficiency and low cost converters are very important to obtain a cost-effective solution. In addition, the power electronics converters must be chosen in respect to the characteristics of these generation resources. In this regard, this paper introduces an overview on different of DC–DC converter topologies and investigates their applicability for fuel cell and ultracapacitor electricity generators based on the electrical output characteristics of these resources. Thus, the fuel cell and ultracapacitor characteristics and properties are presented in this paper. A number of configurations that can be employed to interface the ultracapacitor with the fuel cell generator forming part of a DC bus microgrid are also presented. [ABSTRACT FROM AUTHOR]

The energy sector has links to various local and global issues. Wind energy, a low carbon renewable energy source, exhibits promise in dealing with many crucial issues, such as sustainable development and global warming. While the synergy between many advantages of wind energy and favorable laws makes the wind market bloom, efficient and reliable utilization of a wind system requires investment in the infrastructure beyond power generation facilities. To increase the reliability of the current electrical systems and to make them more capable of dealing with the challenges of wind energy would be possible with the utilization of smart grid systems. The integration of sustainable energy resources with smart grids such that energy becomes bidirectional has many far-reaching advantages in the sector. Therefore, this paper addresses the main topics of wind energy and smart grids and proposes a framework for the implementation of a smart grid in İzmir for wind energy. This application model is an example and can be of interest to researchers from many countries seeking to integrate renewable resources with fossil fuels to meet their future energy needs. [ABSTRACT FROM AUTHOR]

With the advancement in technologies, the power requirement around the globe is tremendously increasing, putting extra loads on grids. The existing grids cannot bear that load and also do not provide the interface with Distributed Renewable Energy Sources (DRES). Building new lines and substations alone do not serve the purpose of overcoming energy shortfall. Thus a major transformation in electricity infrastructure is need of the hour to meet the ever growing demands of electricity. Converting current power management system to a smart autonomic system is pertinent to achieve an increasing amount of renewable energy generation. This paper presents a comprehensive review of advances in control of smart grids. Various robust and adaptive strategies are spotlighted with a detailed description of control of overloads and power smart grids. Also, power generation, storage and management techniques and development of operational schedule of sources and loads are elaborated. Recently reported systems and Information and Communication Technologies (ICT) techniques in smart grid are highlighted. Renewable energy has potential to eliminate the current electricity crisis in Pakistan's energy sector. The solar, wind, hydro and biogas/biomass are the alternative energy resources found abundantly in the country, which have tremendous potential to offer environment-friendly energy solutions. This in-depth study reveals that a lot of opportunities and potential of smart grid technology exist in developing countries like Pakistan that need to be exploited so as to cope with energy crisis. [ABSTRACT FROM AUTHOR]

The high penetration of renewable generations in the distribution system (DS) has introduced more uncertainties and technical challenges in the operation of the grid-like voltage variation; degraded protection; altered transient stability; two-way power flow; and increased fault level. The reverse power flow due to high penetration of renewable generation may result to voltage rise which distribution network operators (DNOs) may not be able to control effectively. To that effect, this paper therefore reviews the impact of renewable generations such as solar photovoltaic (PV) and wind energy on distribution system with voltage control strategies. The work reveals that the application of smart grid technologies such as demand side integration (DSI) and energy storage (ES) mitigates voltage variation problems with minimum network reinforcement. [ABSTRACT FROM AUTHOR]

Electric vehicles can become integral parts of a smart grid, since they are capable of providing valuable services to power systems other than just consuming power. On the transmission system level, electric vehicles are regarded as an important means of balancing the intermittent renewable energy resources such as wind power. This is because electric vehicles can be used to absorb the energy during the period of high electricity penetration and feed the electricity back into the grid when the demand is high or in situations of insufficient electricity generation. However, on the distribution system level, the extra loads created by the increasing number of electric vehicles may have adverse impacts on grid. These factors bring new challenges to the power system operators. To coordinate the interests and solve the conflicts, electric vehicle fleet operators are proposed both by academics and industries. This paper presents a review and classification of methods for smart charging (including power to vehicle and vehicle-to-grid) of electric vehicles for fleet operators. The study firstly presents service relationships between fleet operators and other four actors in smart grids; then, modeling of battery dynamics and driving patterns of electric vehicles, charging and communications standards are introduced; after that, three control strategies and their commonly used algorithms are described; finally, conclusion and recommendations are made. [ABSTRACT FROM AUTHOR]

Interconnection between countries and surrounding countries provides a large power grid. With the improvement of wind power technology, increase of wind power capacity, the impact of wind power on the grid has become an important research topic as well. Large power systems are facing new challenges, such as increasing penetration of renewable energy sources, in particular wind generation, growing demands, limited resources, and competitive electricity markets. Under these conditions, the large power systems have had to confront some major operating problems in voltage regulation, power flow control, protection, and stability. The traditional stand alone (unit) protection schemes are not capable to protect large scale grid system, particularly after large disturbances. As it is known large disturbances might provoke a series of cascading outages, which can lead to the total system blackout and catastrophic consequences to the equipment and society. Current approaches adopted for implementing protection are not significant advancement in such configuration. Advancements in the protection and control have to be brought into the domain of wind farm application to address the specific needs and challenges of this configuration. This paper introduces a complete survey about traditional protection techniques for transmission line connected with renewable resources and the main shortcoming points for such techniques. Also the most recent techniques and new trends of the protection available nowadays for applying and facing such challenges are given. Smart devices deployed on the smart grid and smart based wireless devices can enhance and provide novel ideas for facing such challenges. [ABSTRACT FROM AUTHOR]

The paper presents a literature review on smart grid concepts, considering generation, transmission and distribution of electricity besides smart consumption, including smart home, Demand-Side Response Programs, and Active Demand-Side Management. An analysis of the smart grid development in Brazil is performed, presenting the policy and regulation efforts beyond investments. This analysis takes account a pattern for smart grid development, and one may observe that Brazil is going towards a smart grid full implementation; however it could take decades and requires adjusts from govern, regulatory agency, utilities and consumers, and more investments. Moreover, some of the major smart grid projects in Brazil are presented, and their characteristics are compared considering the technologies used, location and electric utility goals. Depending on the electric utilities objectives, one may observe similarities and differences between concepts adopted and location of the Brazilian smart grid pilot projects. The first objective is the validation and replicability of the pilot project implemented; once, the project location is a sample of the utility׳s energy market or it is a particular area of interest, like an off-grid powered island with high environmental restrictions, for instance. The second objective is creating a model of sustainable smart grid with national visibility, once the project location is a touristic place. The conception of smart grid is aligned with sustainability, and it is a tendency in Brazil a massive entry of smart grid technologies in the next years. [ABSTRACT FROM AUTHOR]

Smart grids and smart meters are central for the integration of distributed, renewable electricity generation. For smart grids to operate smoothly, technology standards are essential. In Europe, a multitude of different standards have been developed, making standard selection a complex task for electric utilities. With this paper we make three contributions: firstly, we identify 17 wired and wireless communication standards for smart metering in Europe. Secondly, we develop and describe a comprehensive set of technical and non-technical criteria for standard selection. Finally, we compare the existing standards against these criteria. We find that none of the standards is superior in all aspects, resulting in major trade-offs for decision makers. Moreover, we reveal the competing nature and missing interoperability of standards, which makes a seamless integration of smart grids across different regions difficult and poses major challenges for the development of complementary smart grid technologies. [ABSTRACT FROM AUTHOR]

In some countries, photovoltaic (PV) technology is at a stage of development at which it can compete with conventional electricity sources in terms of electricity generation costs, i.e., grid parity. A case in point is Germany, where the PV market has reached a mature stage, the policy support has scaled down and the diffusion rate of PV systems has declined. This development raises a fundamental question: what are the motives to adopt PV systems at grid parity? The point of departure for the relevant literature has been on the impact of policy support, adopters and, recently, local solar companies. However, less attention has been paid to the motivators for adoption at grid parity. This paper presents an in-depth analysis of the diffusion of PV systems, explaining the impact of policy measures, adopters and system suppliers. Anchored in an extensive and exploratory case study in Germany, we provide a context-specific explanation to the motivations to adopt PV systems at grid parity. [ABSTRACT FROM AUTHOR]

Micro-grids have been developed for over two decades as building blocks for future smart grids. Micro-grids have appeared with the advantages such as control flexibility, easy connection of renewable resources, high efficiency and immunity to large area blackouts. Similar to other countries, development of micro-grids in China has gone through from the early stage of AC microgrids to the current varieties of AC, DC and hybrid AC/DC micro-girds based on their applications. Many technical problems have been solved and new problems are continuously appeared during the development process. This paper presents a past, today and future for development of micro-grids in China. The current status of micro-grids and renewable energy sources in China is presented first. The topologies of the micro-grids in China are then introduced and classified into three types. Different control techniques of the micro-grids are introduced. Finally, technical challenges and future prospect of micro-grids in China are discussed. [ABSTRACT FROM AUTHOR]

Traditional electricity grid offers demand side management (DSM) programs for industrial plants and commercial buildings; there is no such program for residential consumers because of the lack of effective automation tools and efficient information and communication technologies (ICTs). Smart Grid is, by definition, equipped with modern automation tools such as home energy management system (HEMS), and ICTs. HEMS is an intelligent system that performs planning, monitoring and control functions of the energy utilization within premises. It is intended to offer desirable demand response according to system conditions and price value signaled by the utility. HEMS enables smart appliances to counter demand response programs according to the comfort level and priority set by the consumer. Demand response can play a key role to ensure sustainable and reliable electricity supply by reducing future generation cost, electricity prices, CO 2 emission and electricity consumption at peak times. This paper focuses on the review of HEMSs and enabled demand response (DR) programs in various scenarios as well as incorporates various DR architectures and models employed in the smart grid. A comprehensive case study along with simulations and numerical analysis has also been presented. [ABSTRACT FROM AUTHOR]