Electric Power Grid Research Articles

Battery storage systems in electric power grid: A review

Renewable energy within the utility grid has increased during the previous decade. Severe issues have been raised about the dependability, effectiveness, and efficiency of energy infrastructure. Therefore, energy storage devices have considerably enhanced the network’s accuracy and reliability. Battery energy storage systems (BESS) are among the greatest widely used storage solutions because they have several advantages over traditional power sources, including fast and accurate response, flexibility, and predictability. They are regarded as a reasonable alternative to the threat of climate change. This paper provides a comprehensive evaluation of the BESS’s optimum size targets, limitations, methodology, benefits and disadvantages. Furthermore, energy storage technologies and improved application targets have been presented and discussed for greater clarity. This study focuses primarily on BESS deployments, methodologies, and environmental impact. BEES innovations and achievements for electrical networks are also compared to other energy storage technologies. Concerns and obstacles are discussed to offer researchers in BESS a comprehensive picture. Finally, this study provides several essential ideas that economists and practitioners can use to design a fruitful, robust, efficient, and resilient BESS for a brighter and more optimal deployment.

Powering Through Wildfires: An Integrated Solution for Enhanced Safety and Resilience in Power Grids

Safeguarding the nation’s electrical infrastructure and personnel against natural and man-made disasters, and ensuring a continuous, reliable, and resilient supply of energy are among the top priorities for the electric industry. In recent years, wildfires have been remarkably threatening the safety and security of electric power grids demanding innovative frameworks for ensured resilience. Our proposed approach focuses on mitigation of wildfire disruptions that, once occur, can jeopardize the well-being of electrical equipment and the safety of the personnel. The proposed framework first offers a comprehensive wildfire characterization package that can spatiotemporally monitor and analyze the wildfire behaviors, i.e., wildfire intensity, arrival time, and binding paths from ignition points to electrical equipment. This allows power system operators to make proactive decisions before the fire approaches the electrical elements, e.g., power distribution lines. Next, a decision support tool for wildfire management in power grids is proposed such that various local generation resources,—i.e., distributed renewable energy resources and energy storage systems, can be effectively employed to mitigate the wildfire impacts on the power grid. The proposed integrated solution technology ensures a significant reduction in power outages and enhances the safety and resilience of the power grid and the operating personnel.

Dynamic stability of electric power grids: Tracking the interplay of the network structure, transmission losses, and voltage dynamics.

Dynamic stability is imperative for the operation of the electric power system. This article provides analytical results and effective stability criteria focusing on the interplay of network structures and the local dynamics of synchronous machines. The results are based on an extensive linear stability analysis of the third-order model for synchronous machines, comprising the classical power-swing equations and the voltage dynamics. The article addresses the impact of Ohmic losses, which are important in distribution and microgrids but often neglected in analytical studies. We compute the shift of the stability boundaries to leading order, and thus provide a detailed qualitative picture of the impact of Ohmic losses. A subsequent numerical study of the criteria is presented, without and with resistive terms, to test how tight the derived analytical results are.

Expert-Guided Security Risk Assessment of Evolving Power Grids

Electric power grids, which form an essential part of the critical infrastructure, are evolving into highly distributed, dynamic networks in order to address the climate change. This fundamental transition relies on extensive automation solutions based on communications and information technologies. Thus, it also gives rise to new attack points for malicious actors and consequently, increases the vulnerability of the electric energy system. This study presents a qualitative assessment of power grid cybersecurity through expert interviews across countries in Europe and the U.S. to gain understanding of the latest developments and trends in the cybersecurity of future electric energy systems. The horizon of the assessment is 10 years spanning until the early 2030s. Thereafter, the study identifies how and to which extent the risks identified to be most significant are understood and addressed in the latest research and industry publications aiming at identifying areas deserving specific further attention. The most significant threats based on the assessment are False Data Injection (FDI), Denial of Service (DoS) supply chain, and ransomware and malware attacks.

Aerodynamic limits air injection for heavy-duty gas turbine: Compressor aerodynamic limits for power augmentation and ramp-up capabilities

Improved operational flexibility of gas turbines can play a major role in stabilising the electric power grid, by backing up intermittent renewable power. Gas turbines offer on-demand power and fast dispatch of power that is vital when renewable power reduces. This has brought about increasing demand to improve the ramp-up rate of gas turbines. One approach is through the injection of compressed air from energy storage or an auxiliary compressor. This method is the focus of the present work, which shows for the first time, the implications and limits of compressor air injection in a high-fidelity Computational Fluid Dynamics model (CFD). The 3D multi-stage model of the compressor was developed in ANSYS CFX v19.2, while the boundary conditions related to the injection cases have been obtained from a corresponding 0D engine model. The upper limits to air injection determine how much air can be injected into the engine, providing indicative values of power augmentation and ramp-up rate capabilities. These have been previously addressed by the authors using 0D models that do not consider the compressor aerodynamics in great detail. The CFD study has shown that for power augmentation, 16% of compressed air (based on compressor exit) is allowed based on the onset of stall. It also shows that increasing air injection amplifies losses, blockage factor and absolute velocity angle. Also, about 30% of the blade span from the hub is dominated by a rise in the total pressure loss coefficient, except the outlet guide vane for which separation occurs at the tip. For the ramp-up rate analysis, up to 10% air injection is shown to be sustainable. The work shows that the improvements in the 0D analytical engine model are plausible, in addition to demonstrating similar limits at different ambient temperatures.

A novel scheme for control by active and reactive power utilized in gearless variable speed wind turbine system with PMSG connected to the grid

Introduction. As a result of increasing fossil fuel price and state-of-the-art technology, more and more residential and commercial consumers of electricity have been installing wind turbines. The motivation being to cut energy bills and carbon dioxide emissions. Purpose. The main goal of this work is developing a control scheme for a variable speed wind turbine generator in order to produce utmost power from varying wind types, and variable wind speed. Novelty. This research paper presents an IGBT power converter control scheme for active power in relation to wind speed and reactive power by adjusting Q-reference (Qref) value in a gearless variable speed wind turbine with permanent magnet synchronous generator. Methods. An effective modelling and control of the wind turbine with the suggested power converter is executed by utilizing MATLAB/Simulink software. The control scheme consists of both the wind turbine control and the power converter control. Simulation results are utilized in the analysis and deliberation of the ability of the control scheme, which reveals that the wind turbine generator has the capability to actively sustain an electric power grid network, owing to its ability to independently control active and reactive power according to applied reference values at variable wind speed. Practical value. This research can be utilized for assessing the control methodology, the dynamic capabilities and influence of a gearless variable-speed wind energy conversion system on electric power grids. A case study has been presented with a (3×10 MW = 30 MW) wind farm scheme.

Digital Twin Concept Developing on an Electrical Distribution System—An Application Case

Through the transformation that the electrical sector has been passing by, improvements in asset management and the guarantee of sustainable and quality services have become essential aspects for power companies. Thus, the digitalization of energy utilities presents itself as an important and crucial process. A concept that involves a variety of innovative trends is the digital twin. It consists of a 3D virtual replica of existing physical objects and real-time monitoring of certain measures. By developing a digital twin in the electrical power grid, a virtual replica of the network is obtained providing network virtual maps, 3D asset models, dynamic and real-time data of grid assets, and IoT sensing. All these data can feed a platform where AI-based models and advanced field operation technologies and solutions will be applied. With a Network Digital Twin©development, applications involving on-field activities can be improved through augmented reality (AR) and virtual reality (VR) to enhance workforce operations. This paper discusses the best practices for the development of a digital twin for the electrical power sector. These practices were found during the development of a project carried out by Enel Distribuição São Paulo, applying a living lab concept in the densest region of Brazil. The results of this paper present 3D images captured with specialized tools, and how they influence the workforce activities of human interface operation. Furthermore, financial and operational returns are presented through a cost–benefit analysis for each relevant aspect.

Short-Term Forecasting of Hourly Electricity Power Demand

The optimal use of electric power consumption is a fundamental indicator of the normal use of energy resources. Its quantity depends on the loads connected to the electric power grid, which are measured on an hourly basis. This paper examines forecasting methods for hourly electrical power demands for 7 days. Data for the period of 1 January 2015 and 24 December 2020 were processed, while the models' forecasts were tested on actual power load data between 25 and 31 December 2020, obtained from the Energy System Operator of the Republic of Bulgaria. Two groups of methods were used for the prognosis: classical regression methods and clustering algorithms. The first group included "moving window" and ARIMA, while the second examined K-Means, Time Series K-Means, Mini Batch K-Means, Agglomerative clustering, and OPTICS. The results showed high accuracy of the forecasts for the prognosis period.

Multi-dimensional evaluation method for new power system

New power system that takes strong smart grid as the platform is supported by source-grid-load-storage interaction and multi-energy complementarity, because the system is green, efficient, flexible and digital. This paper focused on the research of multi-dimensional evaluation method of the new power system. Firstly, the internal and external elements of the new power system were sorted out, and KPI indicators were obtained through the analysis of the logical relationship of indicators. Secondly, this paper innovatively proposed to use “Generation Side Grid and Load” (GSGL) as the internal element and “Reliable Efficient Green and Intelligent” (REGI) as the evaluation effect. Meanwhile, this paper innovatively put forward a new multi-dimensional evaluation system of power system, with 4 secondary indicators and 16 tertiary indicators. Finally, the AAHM-weighted grey relational TOPSIS comprehensive evaluation model was constructed, and the validity and applicability of the proposed evaluation index system and model method were verified by numerical examples. Through the example analysis, under the new multi-dimensional evaluation system of power system, the comprehensive evaluation results and ranking of different provincial power enterprises were obtained. This paper provides theoretical support to further promote the transformation and upgrading of energy and electric power industry and power grid enterprises to speed up the construction of safe, reliable, green, efficient and intelligent modern power grid.

Space Solar Power- An Option for the Future

In the movie "Apollo 13" the engineers had a discussion on howto get the astronauts home safely. A number of suggestions were madeand they began to debate the options. One engineer stopped the conver-sation, and said: "Power is everything."None of the options was possible without power.Our energy resources are indeed finite, on a much larger scale ofcourse, but they must be managed. Today, more than 40% of the earth'sfive billion people are not connected to electric power grids. Althoughthe United States' more than 250 million citizens, along with other in-dustrialized nations , are the largest consumers of electricity, ourconsumption grows by only 1.4% per year. The rest of the world is in-creasing consumption by 2.5% per year.The US Department of Energy has estimated that by the year 2015,the consumption of electricity in developing countries (80% of theworld's population) will equal that of industrialized nations. Buildingmore power plants that burn nonrenewable fuels has environmentalimpacts and nuclear energy receives significant oppos ition from thegeneral public. No one energy source will satisfy this demand, so Iwould like to introduce to you an option that to the best of my knowl-edge has not been discussed in this or any AEE publication, that is SpaceSolar Power (SSP).

Cascading failures in isotropic and anisotropic spatial networks induced by localized attacks and overloads

Cascading failures are catastrophic processes that can destroy the functionality of a system, thus, understanding their development in real infrastructures is of vital importance. This may lead to a better management of everyday complex infrastructures relevant to modern societies, e.g., electrical power grids, communication and traffic networks. In this paper we examine the Motter–Lai model (2002 Phys. Rev. E 66 065102) of cascading failures induced by overloads in both isotropic and anisotropic spatial networks, generated by placing nodes in a square lattice and using various distributions of link lengths and angles. Anisotropy has not been earlier considered in the Motter–Lai model and is a real feature that may affect the cascading failures. This could reflect the existence of a preferred direction in which a given attribute of the system manifests, such as power lines that follow a city built parallel to the coast. We analyze the evolution of the cascading failures for systems with different strengths of anisotropy and show that the anisotropy causes a greater spread of damage along the preferential direction of links. We identify the critical linear size, l c, for a square shaped localized attack, which satisfies with high probability that above l c the cascading disrupts the giant component of functional nodes, while below l c the damage does not spread. We find that, for networks with any characteristic link length, their robustness decreases with the strength of the anisotropy. We show that the value of l c is finite and independent of the system size (for large systems), both for isotropic and anisotropic networks. Thus, in contrast to random attacks, where the critical fraction of nodes that survive the initial attack, p c, is usually below 1, here p c = 1. Note that the analogy to p c = 1 is also found for localized attacks in interdependent spatial networks (Berezin et al 2015 Sci. Rep. 5 8934). Finally, we measure the final distribution of functional cluster sizes and find a power-law behavior, with exponents similar to regular percolation. This indicates that, after the cascade which destroys the giant component, the system is at a percolation critical point. Additionally, we observe a crossover in the value of the distribution exponent, from critical percolation in a two-dimensional lattice for strong spatial embedding, to mean-field percolation for weak embedding.

Authenticated Key Agreement Protocol for Secure Communication Establishment in Vehicle-to-Grid Environment With FPGA Implementation

Vehicle-to-grid (V2G) technology enables bidirectional energy flow between the electric vehicle and power grid thereby making the electric vehicle as a virtual power plant. This seamless exchange of energy flow is possible only when the entities involved communicate wirelessly in a secured manner. In order to ensure privacy-preserving in the V2G communication, development of a novel key establishment protocol is an active area of research. This article presents a lightweight mutual authentication and key establishment protocol for secure V2G communication among the electric vehicle user, charging station, and utility service provider. The correctness of the proposed protocol is verified using the formal method BAN logic, and many of its security threats are analyzed informally. Further, the protocol is compared for its security and efficiency with the related protocols in the literature under various aspects, and the comparison results show that our protocol outshines the others. The functional correctness of the protocol is also verified in Xilinx Zynq-7000 series FPGA board so that it can be deployed in any real-time applications.

Absence of pure voltage instabilities in the third-order model of power grid dynamics.

Secure operation of electric power grids fundamentally relies on their dynamical stability properties. For the third-order model, a paradigmatic model that captures voltage dynamics, three routes to instability are established in the literature: a pure rotor angle instability, a pure voltage instability, and one instability induced by the interplay of both. Here, we demonstrate that one of these routes, the pure voltage instability, requires infinite voltage amplitudes and is, thus, nonphysical. We show that voltage collapse dynamics nevertheless exist in the absence of any voltage instabilities.

Online Ensemble Approach for Probabilistic Wind Power Forecasting

Probabilistic wind power forecasting is an important input in the decision-making process in future electric power grids with large penetrations of renewable generation. Traditional probabilistic wind power forecasting models are trained offline and are then used to make predictions online. However, this strategy cannot make full use of the most recent information during the prediction process. In addition, ensemble learning is recognized as an effective approach for further improving forecasting performance by combining multiple forecasting models. This paper studies an online ensemble approach for probabilistic wind power forecasting by taking full advantage of the most recent information and leveraging the strengths of multiple forecasting models. The online ensemble approach is first formulated as an online convex optimization problem. On this basis, a quantile passive-aggressive regression model is proposed to solve the online convex optimization problem. Case studies and comparisons with other online learning methods are conducted on an open wind power data set from Belgium. Results show that the proposed method outperforms competing methods in terms of pinball loss and Winkler score with high reliability.

An Inrush Current Limiting Method for Grid-Connected Converters Considering Grid Voltage Disturbances

To support the electric power grid, some grid-connected converters are required to ride through abnormal grid conditions, including voltage disturbances. However, at the moment, when a grid voltage disturbance happens, a large inrush current could be induced due to the large difference between the grid and converter output pulsewidth modulation (PWM) voltages. This inrush current could be more severe in the faster switching SiC-based multilevel converter, which only needs a small filter inductance to meet its normal operation requirements, such as harmonics and peak ripple currents. In this article, a PWM mask method is used to limit the inrush current. With this method, the inrush current can be effectively limited to a preset value and can help the converter ride through grid voltage disturbances. The method is validated through experiments conducted on a single-phase SiC-based five-level converter considering low voltage, high voltage, and phase angle disturbances.

A residential labeled dataset for smart meter data analytics

Smart meter data is a cornerstone for the realization of next-generation electrical power grids by enabling the creation of novel energy data-based services like providing recommendations on how to save energy or predictive maintenance of electric appliances. Most of these services are developed on top of advanced machine-learning algorithms, which rely heavily on datasets for training, testing, and validation purposes. A limitation of most existing datasets, however, is the scarcity of labels. The SustDataED2 dataset described in this paper contains 96 days of aggregated and individual appliance consumption from one household in Portugal. The current and voltage waveforms were sampled at 12.8 kHz, and the individual consumption of 18 appliances was sampled at 0.5 Hz. The dataset also contains the timestamps of the ON-OFF transitions of the monitored appliances for the entire deployment duration, providing the necessary ground truth for the evaluation of machine learning problems, particularly Non-Intrusive Load Monitoring. The data is accessible in easy-to-use audio and comma-separated formats.

Power quality enhancement through ancillary services provided by power electronic converters

Modern electrical power grids are susceptible to several problems in terms of power quality due to the integration of renewable energy sources, the connection of nonlinear loads, and power electronics-based devices. In this sense, this work proposes a novel nonlinear control scheme that allows, through the use of a power electronic converter, to provide ancillary services to the electrical power grid, intending to achieve three different control objectives: voltage regulation, harmonic distortion compensation, and the power factor correction at a power system node, depending on the end-user requirements, and by doing so enhance the power quality. The proposed control scheme uses nested control loops based on super-twisting sliding modes, nonlinear optimal tracking control, and a fast-convergent harmonic estimator with a decentralized structure. Simulation results validate the effectiveness of our proposed scheme.

Generalized Contingency Analysis Based on Graph Theory and Line Outage Distribution Factor

Identifying the multiple critical components in power systems whose absence together has severe impact on system performance is a crucial problem for power systems known as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(N-x)$</tex-math></inline-formula> contingency analysis. However, the inherent combinatorial feature of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N-x$</tex-math></inline-formula> contingency analysis problem incurs by the increase of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$x$</tex-math></inline-formula> in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(N-x)$</tex-math></inline-formula> term, making the problem intractable for even relatively small test systems. We present a new framework for identifying the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N-x$</tex-math></inline-formula> contingencies that captures both topology and physics of the network. Graph theory provides many ways to measure power grid graphs, i.e., buses as nodes and lines as edges, allowing researchers to characterize system structure and optimize algorithms. This article proposes a scalable approach based on the group betweenness centrality concept that measures the impact of multiple components in the electric power grid as well as line outage distribution factors that find the lines whose loss has the highest impact on the power flow in the network. The proposed approach is a quick and efficient solution for identifying the most critical lines in power networks. The proposed approach is validated using various test cases, and results show that the proposed approach is able to quickly identify multiple contingencies that result in violations.

Grid-Forming Inverters for Grid-Connected Microgrids: Developing “good citizens” to ensure the continued flow of stable, reliable power

The electric power grid is in transition. For nearly 150 years it has supplied power to homes and industrial loads from synchronous generators (SGs) situated in large, centrally located stations. Today, we have more and more renewable energy sources—photovoltaic (PV) solar and wind—connected to the grid by power electronic inverters. These inverter-based resources (IBRs) do not have the same characteristics as SGs, such as inertia and high fault current. This mismatch has not been a problem until now. Inverters have assumed that the grid is strong and will provide a stable and clean voltage and that they are able to inject real power into the grid without undue impact on its operation.

Rotor Loss and Thermal Analysis of Synchronous Condenser Under Single-Phase Short-Circuit Fault in the Transmission Line

A synchronous condenser (SC) can provide the reactive power for the Ultra High Voltage Direct Current (UHVDC) converter station to keep voltage stability and prevent commutation failure. The single-phase short circuit at a transmission line is prevalent and it can result in not only the voltage drop but also the increase of the rotor loss and temperature of the SC. In order to study the ability of the SC to withstand a single-phase short-circuit fault, the rotor loss and temperature field of a 300-MVar SC are studied by coupling the electromagnetic and temperature field models of the SC with the models of the electric circuit and power grid. The loss distributions in the rotor core and slot wedges are calculated under a single-phase short-circuit fault at the different positions of the transmission line. The rotor temperature distributions of the SC under over- and under-excitations are calculated and verified by the experiments. The influence of short-circuit duration on the rotor temperature of the SC is calculated under the single-phase short circuit. The study can provide a theoretic basis for the improvement of the operating ability of the SC under the single-phase short-circuit faults.