Renewable microgrid state estimation using the Internet of Things communication network

Traditional power grid is currently transforming to next generation via Smart Grid (SG). For Smart Grid operation it is necessary to provide two-way communication with field devices. Internet of Things (IoT) trend with rising communication requirements from the aspect of bandwidth influences Smart Grid. The amount of data that will be exchanged between the Control Center and field devices is going to grow significantly in the near future. This will put additional load on communication infrastructure. One of the challenges that Smart Grid communication infrastructure needs to address is providing adequate quality of service (QoS) while taking in consideration available bandwidth and requirements for Smart Grid Operational Technology (SG OT) applications. This paper presents the influence of communication infrastructure congestion on Smart Grid. Special focus was put on State Estimation as one of the most critical real-time Smart Grid applications. State Estimation communication traffic is emulated and observed when the network is under different levels of congestion. Obtained test results on analyzed network demonstrates congestion impact on State Estimation. Congestion can severely impact State Estimation performance by providing outdated field information. The results and possible solutions to this problem are discussed.

The smart grid, perceived as the next generation power grid, uses two-way flow of electricity and information to create a widely distributed automated energy delivery network. By grouping distributed renewable energy generations and loads, a microgrid, which is seen as one of the cornerstones of the future smart grids, can disconnect from the macrogrid and function autonomously. This intentional islanding of generations and loads has the potential to provide a higher local reliability than that provided by the power system as a whole. One of the fundamental issues for a user in an islanded microgrid is how to find the one among the distributed renewable energy resources (DRERs) in a microgrid, which can supply the power most efficiently, effectively and reliably, as its power supply source. This problem is difficult since the power pattern of renewable resources, such as wind and solar, is variable and generally speaking is not easy to accurately predict. In order to solve this problem, we first propose a distributed DRER discovery approach to discover all the available DRERs within a microgrid. Furthermore, based on the online machine learning theory, we propose two distributed algorithms according to the information the user can obtain, in order to compute a good DRER access strategy, with no assumption on what distribution the power patterns of the DRERs follow. We prove that when the time horizon is sufficiently large, on average the upper bound on the gap between the expected profit obtained at each time slot by using the global optimal strategy and that by using our algorithms is arbitrarily small.

This paper investigates the smart grid communication infrastructure with an upgrade of existing electricity networks and advanced ICT technologies, intelligent devices & system. Considering that the energy utilities have been play an increasingly important role in our modern world, smart grid technology also introduces new security challenges that must be addressed. This paper focuses on the implementation of smart grid communication architecture to develop a real time situation and study the security challenges that is occurring on its communication infrastructure. A micro grid structure with particular generation and distribution specification along with its relevant communication infrastructure is designed to analyze the security challenges. The studies have been performed on the basis of digital computer simulation approach using the Power Factory 14.1 software package. Some dynamic system events were formulated to link the designed micro grid architecture to the real time situation and to analyze the change in different system parameters due to cyber-attack and effect of these changes are examined on the smart grid generation and distribution network. This analysis is further used for identifying the cyberattack prone areas to ensure cyber security and determine the methods required for enabling cyber security in smart grid communication infrastructure.

Smart grids are electric grids that utilize advanced technologies of monitoring, control, and communication to supply reliable and secure energy, improve the efficiency of the system, and provide flexibility to the prosumers. The beginning of the smart grid era and the development in modern infrastructures of metering, communication, and energy storage have revolutionized the power grid. Smart grids are developed with complex physical networks and cyber systems thus enabling smart grids for the Internet of Energy (IoE). IoE is the cloud where sources of power generation and loads of power consumption are embedded with intelligence. Modern electric power grids are integrated with sensors used to provide measurements. The sensor measurements and the complex applications of various sensors cause a need for Cyber-Physical System (CPS). CPS is a class of systems that integrates physical process, computation, and networking. The CPS model of the smart grid helps in modeling and simulation for evaluation of the system performance and characteristics. The CPS model of the smart grid must enable the smart grid to be robust, 2allow future extensions, and compatible with web service technologies. The power generation sources and loads such as smart buildings are the physical layers, the sensors used for measurements form the cyber-physical integration and the data storage and processing using IOE forms the cyber layer of the smart grid. The CPS model of the smart grid helps in the integration of intelligent devices and allied information and communication technologies for robust and reliable operation in smart grids. In the smart grid paradigm, the energy management system has a vital role to increase the efficiency and reliability of the system. This chapter presents a CPS model for smart grid and the challenges associated with the development of the CPS model. In addition, this chapter describes the energy management system model of the smart grid.

This paper presents a real-time implementation of multi-agent based game theory reverse auction model for microgrid market operation featuring conventional and renewable distributed energy resources (DER). Studies were conducted for a grid connected microgrid consisting of a synchronous generator, two inverter-based generation units and a combined load. The Multi-agent based platform was applied to monitoring, controlling and per-forming the reverse auction process of the DER. A competitive game-theory reverse auction model was investigated to schedule the DER unit commitment with hour-ahead market approach for the twenty-four hours of the day. The proposed methodology was realistically implemented and operated at Florida International University, Smart Grid Test system. The investigation shows that the proposed algorithm and the industrial based hardware structure can be implemented in existing electric utility grid as new assets of the system are added.

Smart grids have benefits such as high reliability and availability due to distributed energy resources (DERs) which are integrated to the power transmission and distribution grid. These DERs will maintain an uninterrupted power supply for electricity consumers in a case of isolation from the primary electricity grid due to failure of the system. The integration of DERs into the transmission and distribution grid introduces new consequence for distributed network operators (DNOs). In traditional electricity grid, power flow is happening normally from the bulk generation stations to consumers and all control operations are done at the centralized control station. In the modern electricity grid with DERs, the energy follows in both directions via substations due to randomly spread energy sources at the lower voltage side. Although distribution network was considered as a static system without major control operations or reconfiguration requirements. For a smart grid, distribution network can be considered as a dynamic system due to DERs. Power routing is an emerging concept. Its main purpose is to make the distribution network more flexible which will help to solve the technical issues related to DERs. With the introduction of DERs, DNOs have faced many challenges. Communication is one of major challenges in DNO Technology. Nowadays most of the communication architectures are based on the Internet that creates major security issues with the system. Cyber-security Enabled Communication Architecture is the most important concept for Power Routing. In this paper we introduce a cyber-security enabled communication architecture that facilitates the security for the information of an electricity grid.

A multi-level multi-objective strategy for eco-environmental management of electricity market among micro-grids under high penetration of smart homes, plug-in electric vehicles and energy storage devices

In the last century, there was no major alteration in the structure of power grids. Studies have shown that existing infrastructure is no longer suitable to meet requirements of the future. To overcome the challenges and fulfil future requirements, we need a network that is reliable, efficient and intelligent. This has led to the development of emerging concept of smart grid (SG). Smart grids are the next generation of electrical power grids; a promising solution to overcome energy crises. Smart grid system is the integration of advanced computing and communication technologies with power system infrastructure. In this paper, we provide a survey of the communication infrastructure in smart grids that includes communication architecture and different network compositions, technologies, and intelligent functions that are employed in this architecture. This survey is expected to provide improved understanding of the technologies, its potential benefits and impact. Moreover, we intend to provoke interest amongst the research community to discover more about this emerging area to realize the potential of smart grid concept.

Modeling a complete Internet of Things (IoT) infrastructure is crucial to assess its availability and security characteristics. However, modern IoT infrastructures often consist of a complex and heterogeneous architecture and thus taking into account both architecture and operative details of the IoT infrastructure in a monolithic model is a challenge for system practitioners and developers. In that regard, we propose a hierarchical modeling framework for the availability and security quantification of IoT infrastructures in this paper. The modeling methodology is based on a hierarchical model of three levels including (i) reliability block diagram (RBD) at the top level to capture the overall architecture of the IoT infrastructure, (ii) fault tree (FT) at the middle level to elaborate system architectures of the member systems in the IoT infrastructure, and (iii) continuous time Markov chain (CTMC) at the bottom level to capture detailed operative states and transitions of the bottom subsystems in the IoT infrastructure. We consider a specific case-study of IoT smart factory infrastructure to demonstrate the feasibility of the modeling framework. The IoT smart factory infrastructure is composed of integrated cloud, fog, and edge computing paradigms. A complete hierarchical model of RBD, FT, and CTMC is developed. A variety of availability and security measures are computed and analyzed. The investigation of the case-study’s analysis results shows that more frequent failures in cloud cause more severe decreases of overall availability, while faster recovery of edge enhances the availability of the IoT smart factory infrastructure. On the other hand, the analysis results of the case-study also reveal that cloud servers’ virtual machine monitor (VMM) and virtual machine (VM), and fog server’s operating system (OS) are the most vulnerable components to cyber-security attack intensity. The proposed modeling and analysis framework coupled with further investigation on the analysis results in this study help develop and operate the IoT infrastructure in order to gain the highest values of availability and security measures and to provide development guidelines in decision-making processes in practice.

Several studies and field tests have shown the potential of conservation voltage reduction (CVR) to decrease peak demand, energy consumption, and system losses. Nonetheless, the energy savings achievable by CVR is dependent on the load model, which could be constant power, current, impedance, or any combination of these models. Also, the use of distributed energy resources (DERs) at the distribution level presents a challenge to successful CVR implementation as these resources could cause voltage fluctuations in the system. This paper studies the impact of load models on CVR implementation in a distribution system feeder interfaced with renewable DERs. Load flow analyses are carried out using constant power (PQ) and constant impedance (Z) load models, respectively, and the resulting effects on feeder losses and energy consumption are observed as CVR is implemented. In addition, the impacts of DERs and voltage regulation devices on the feeder voltage profile are analyzed. The feeder losses showed opposite trends with constant PQ and Z loads as CVR is implemented. Overall, the results showed varied impacts of load models and DER output on feeder losses, energy consumption, and bus voltages in the distribution network.

An alternative control design for dc-links used to connect distributed energy resources (DERs) with the main power grid, is proposed and studied for its stability. As DERs are considered to be weak, unpredictable power sources, ac voltage regulation is applied at the side of DER connection while at the grid side, dc voltage and reactive power control is implemented. The challenging issue of achieving these tasks effectively through the design of a rather simple control scheme is examined in this paper. While the traditionally proposed techniques involve parameter-dependent controllers in order to make possible simple linear designs, in this paper, the proposed controllers are clearly simpler ones, parameter-free of proportional-integral (PI) type, but require a more complicated and advanced nonlinear analysis. To that end, incorporating the controllers into the nonlinear dc-link model, the closed-loop system is analyzed by applying advanced Lyapunov techniques combined with input to state stability notions. As shown in the paper, stability and convergence to the equilibrium is guaranteed while the extended simulations presented, fully verify the theoretical analysis.

Evolution of existing power systems towards the Smart Grids has highlighted a great number of potential pitfalls and unsolved issues which are postponing its streamlined progress. Collective control of Distributed Energy Resources (DERs) through the model of Virtual Power Plant (VPP) is one of the key Smart Grid concepts lacking the capability of seamless integration. The IEC 61850 standard defines future-proof automation architecture with core relevance to the Smart Grid. One of the main IEC 61850 contributions are semantic data models describing variety of utility subsystems including DERs. The possibility of using DERs semantics with state-of-the-art industrial automation technologies, such as OPC UA (Unified Architecture), could significantly reduce VPP integration time frame. This article demonstrates how IEC 61850 can benefit from OPC UA technology and accelerate the Smart Grid development. OPC UA is based on Service Oriented Architecture (SOA). It is shown how SOA paradigm provides a value-added feature for controlling VPPs. As a result of analyzing integration methodology between IEC 61850 and OPC UA and by presenting DER servers as SOA-ready devices, VPP automation architecture is proposed.

As electrical power operations tend to be smart grid with strong penetration of renewable energy resources, the evolution of operational technology brings on board another dimension of vulnerabilities with the participation of cyber-physical systems (CPSs). Thus, it becomes essential to perform technical risk assessment and CPS prognosis to envisage the integrity of the system's operational resilience. The communication network elements such as cyber signal transmission, wireless sensor networks (WSNs) and the internet of things (IoTs) converges as a superhighway hub. This seeks to improve on network operations for efficient power delivery of distributed energy resources (DERs) integration grid. It then demands system configuration to be firewalled to avoid operational intrusions and malfunctions. The paper examines the technical threats involved in the paradigm of schemes and mitigation strategies. The areas of study are the vulnerabilities of the DERs integration with CPS, WSNs and IoTs layers. The risk aversion strategies of DERs integration with CPS are also discussed. The study aims to ascertain the intrusion level and responses of the integrated DERs grid in terms of power management. The paper's objective is to present an overview of current developments in the integrated cyber-power systems evolution and the implementation strategies with DERs.

Electricity networks are evolving rapidly with the large‐scale integration of power electronic (PE)‐interfaced distributed renewable energy resources (DRERs). With this rapid deployment of PE‐interfaced renewables, requirements set for the PE‐interfaced DRERs have also evolved to maintain grid security and reliability. Fault ride‐through (FRT) is an essential requirement which should be adhered by DRERs, which will ensure security and reliability of the power system during grid faults. This paper critically reviews the existing FRT standards (grid‐code requirements) and FRT strategies implemented/ proposed for major DRERs, such as wind energy conversion systems (WECSs), solar photovoltaic (PV) systems, and microgrids. According to the review, robust FRT strategies are implemented/proposed DRERs, however, the FRT grid codes are presently developed with the perspective of both synchronous and renewable generation operating in the power system. However, this current approach should be augmented considering 100% PE‐based renewable energy scenarios, and emerging issues, such as high penetration of PE‐interfaced small‐scale renewable generators (e.g., domestic solar‐PV systems) and recurring grid faults, to achieve a sustainable renewable energy future.This article is categorized under: Concentrating Solar Power > Systems and Infrastructure Wind Power > Systems and Infrastructure Photovoltaics > Systems and Infrastructure

Smart microgrids, as the foundations of the future smart grid, combine distinct Internet of Things (IoT) designs and technologies for applications that are designed to create, regulate, monitor, and protect the microgrid (MG), particularly as the IoT develops and evolves on a daily basis. A smart MG is a small grid that may operate individually or in tandem with the electric grid, and it is ideal for institutional, commercial, and industrial consumers, as well as urban and rural societies. A MG can operate in two methods (stand-alone and grid-connected), with the ability to transition between modes due to local grid faults, planned maintenance, expansions, deficits and failures in the host system, and other factors. Energy storage is the process of storing and converting energy that can be used for a variety of purposes, including voltage and frequency management, power backup, and cost optimization. IoT is designed to deliver solutions for optimal energy management, security protocols, control methods, and applications in the MG, with numerous distributed energy resources (DER) and interconnected loads. The use of IoT architecture for MG operations and controls is discussed in this research. With the use of power grid equipment and IoT-enabled technology, MGs are enabling local networks to give additional services on top of the essential supply of electricity to local networks that operate simultaneously or independently from the regional grid. Additionally, this review shows how hybrid AC/DC MGs are advantageous compared to AC and DC MGs. The state-of-the-art optimization techniques and trends in hybrid MG research are included in this work.