Transmission System Operators Research Articles

An angular stable ultra-broadband asymmetric transmission chiral metasurface with efficient linear-polarization conversion

Abstract In this paper, a chiral metasurface is presented to effectively attain an ultra-broadband operation of asymmetric transmission with highly efficient cross-polarization conversion. The efficiency of the asymmetric transmission operation in the frequency band ranging from 6.5 to 13 GHz is above 70%. Additionally, in the frequency range from 3.7 to 14 GHz, the cross-polarization conversion realizes greater than 90% polarization conversion ratio. Asymmetric transmission as well as cross-polarization conversion show angular stability against the incident angle of electromagnetic waves up to 45°. To validate the simulation results, the fabricated chiral metasurface is tested and compared with simulation results. The concepts of asymmetric transmission and linear-polarization conversion are demonstrated and physically explained through the distributions of surface currents over metallic layers. This anticipated work has significant applications in telecommunications and radar, as well as potential use in equipment designed for the manipulation of electromagnetic waves.

Cleaning up while Changing Gears: The Role of Battery Design, Fossil Fuel Power Plants, and Vehicle Policy for Reducing Emissions in the Transition to Electric Vehicles.

Plug-in electric vehicles (PEVs) can reduce air emissions when charged with clean power, but prior work estimated that in 2010, PEVs produced 2 to 3 times the consequential air emission externalities of gasoline vehicles in PJM (the largest US regional transmission operator, serving 65 million people) due largely to increased generation from coal-fired power plants to charge the vehicles. We investigate how this situation has changed since 2010, where we are now, and what the largest levers are for reducing PEV consequential life cycle emission externalities in the near future. We estimate that PEV emission externalities have dropped by 17% to 18% in PJM as natural gas replaced coal, but they will remain comparable to gasoline vehicle externalities in base case trajectories through at least 2035. Increased wind and solar power capacity is critical to achieving deep decarbonization in the long run, but through 2035 we estimate that it will primarily shift which fossil generators operate on the margin at times when PEVs charge and can even increase consequential PEV charging emissions in the near term. We find that the largest levers for reducing PEV emissions over the next decade are (1) shifting away from nickel-based batteries to lithium iron phosphate, (2) reducing emissions from fossil generators, and (3) revising vehicle fleet emission standards. While our numerical estimates are regionally specific, key findings apply to most power systems today, in which renewable generators typically produce as much output as possible, regardless of the load, while dispatchable fossil fuel generators respond to the changes in load.

Alignment of aFRR and mFRR prequalification process in Croatia with the target market design

Commission Regulation (EU) 2017/1485 of 2 August 2017 establishing a guideline on electricity transmission system operation defines a prequalification process as a process to verify the compliance of a reserve providing unit or a reserve providing group with the requirements set by the transmission system operator. Croatian Transmission System Operator Plc. (HOPS) carries out a prequalification process in order for (potential) ancillary service providers to prove their capability of providing ancillary services, which means that the prequalification process is a prerequisite for the provision of ancillary services. As part of the European Network of Transmission System Operators for Electricity, HOPS participates in the European implementation projects PICASSO and MARI, which aim is to establish a single European platform for aFRR and mFRR balancing services. Within the PICASSO and MARI projects, the technical characteristics of the products traded on unique European platforms were defined. This paper analyzes the difference between the requirements from the existing prequalification process rules and the technical requirements for products within the PICASSO and MARI projects, explores practice in Slovenia and Germany and suggests the required adoptions of aFRR and mFRR prequalification processes in Croatia.

The Devil in the details: The factors determining the selection of intrazonal congestion management methods across Europe

The European electricity market is becoming increasingly interconnected, raising questions about how intrazonal congestion management, typically governed by national regulations, interacts with the coupled cross-zonal markets. A major concern is the lack of information regarding intrazonal congestion management methods. This paper addresses this issue by examining different ways in which European transmission system operators (TSOs) use third-party resources to manage congestion in short-term electricity markets. We create a decision-tree-based classification to represent all identified congestion management methods and select three cases for comprehensive evaluation using predefined assessment criteria. While doing so, we identify a trade-off between efficiency and ease of implementation. The balance between these two factors is determined by the severity of the congestion. In a severely congested grid, locational signals are critical, requiring a better alignment between the network representation in the market clearing and the physical network constraints. When the congestion is less severe, TSOs can choose other congestion management methods based on factors such as the predictability of congestion and resource availability. These findings shed light on the complexities of congestion management in an integrated European market and can inform future policy decisions.

Performance analysis of the combination of a pitching wave surge energy converter and floating breakwaters

ABSTRACT Wave Energy Converters (WEC) captured the wave energy while Floating Breakwaters (FB) attenuated the wave energy to make a calm area for harbour activities. This study investigates the combination of a pitching Wave Energy Converter (WEC) and Floating Breakwater (FB) for simultaneous wave energy capture and wave attenuation in harbour areas. Three different configurations were analyzed in nine different hydrodynamic conditions to optimise the performance of both FB and WEC. The results show that the optimised combined device with rectangular draft has the most promising performance, with an average wave transmission operation of 38.8% and a captured power of 533.2 kW across all conditions. Longer arms of the device also lead to better performance. Additionally, wave steepness was found to be a significant factor in the performance of the combined device.

ANALYSIS OF THE POSSIBILITY OF APPLICATION OF HYDRAULIC MOTOR-WHEELS IN TRANSMISSIONS HIGH-SPEED TRACTORS

Goal. The purpose of the article is to assess the possibility of developing a hydraulic fluid power in accordance with the standard traction-speed characteristics of the KhTZ-17021 wheeled tractor with the of using gearless drives of the driving wheels. For this purpose, the calculation of the hydraulic fluid power of the wheeled tractor was performed when using the latest radial piston multi-cycle hydraulic motor-wheels with a wide range of rotation frequency and adjustment of the working volume. Research methodology. An analysis of the traction-speed characteristics of the KhTZ- 17021 wheeled tractor and, based on it, a review of modern high-torque radial-piston multi-cycle hydraulic motors from the point of view of meeting the characteristics of torque and rotation frequency with power limitations relative to the serial model in the full speed range of the tractor. The maximum values of the working volumes of the 4 driving hydraulic motor-wheels and the power supply pump of these hydraulic motors, the torque and pressure drop in the hydraulic drive are calculated, and the modes in which it is necessary to change the working volume of the hydraulic motors from the maximum to the minimum values to work out the traction-speed characteristics. A comparative analysis of radial-piston multi-cycle hydraulic motors was carried out, and for the hydromotor-wheel model MHP27 of the "Poclain Hydraulics" company, which was chosen for the study, the hydraulic principle diagrams were considered with the use of a hydraulic regulation system of four stages of the working volume in hydraulic motors, the use of combined parking and service brakes, as well as an anti-skid system using means of proportional electro-hydraulic automation. The results. High-torque hydraulic motor-wheels of the radial piston type were selected, which make it possible to ensure the operation of the tractor transmission without intermediate gearboxes between the hydraulic motors and wheel hubs, and the calculated value of the working volume of the axial piston pump, which ensures the operation of the tractor transmission in the full speed range. Based on the results of the calculations, it was established that the pressure in the hydraulic drive does not exceed 35 MPa, while values from 40 MPa to 50 MPa are achieved in modern pumps and hydraulic motors. The possibility of increasing the speed of the tractor from standard 35 km/h to promising 50 km/h is shown.

Unbundling of Transmission System Operators – The general European Union Policy and the Case in Georgia

Georgian Transmission System Operator has been certified and nominated as the sole transmission licensee in Georgia upon the specific conditions. Therefore, with the fulfillment of all criteria, the main objective of ownership unbundling (prevention of discrimination, optimization of the use of infrastructure, incentivizing economic investment) can be reached. However, in case of non-compliance with the unbundling ownership requirements and, thus, re-certification of Georgian TSO, the Government of Georgia shall consider the costs of such procedure for the country and, precisely, the state-owned company. Therefore, the responsible public entities shall work with the Regulatory Commission and the Transmission System Operator to ensure timely and proper planning and implementation of necessary activities to meet unbundling ownership requirements.

Reliability based computational model for stochastic unit commitment of a bulk power system integrated with volatile wind power

Reliable and economic operation of transmission systems is one of the most onerous problems faced by the grid operators as a penetration rate of wind energy is on rise. It is a crucial carbon-free source and alleviates dependency upon the conventional resources, though its stochastic and unpredictable nature can cause the risk of random component failures. Therefore, reliability evaluation of the system under wind power is of paramount importance and is suggested as the proposed study. A Reliability based Stochastic Unit Commitment (RSUC) model is proposed for a bulk power system integrated with volatile wind power. It is formulated using Mixed Integer Linear problem considering networks and spinning reserve constraints. The volatility of wind speed is modeled by generating different scenarios using K-means clustering approach with computation of correlation among them using autocorrelation factor and their transition probabilities is proposed using Markov Chain (MC). Further, the system's reliability is evaluated using Loss of Load Probability (LOLP) and Expected Energy Not Supplied (EENS). The proposed approach is investigated on the IEEE 24 Reliability Test System (RTS) under the various overloading and random component outage conditions. Further, its results effectiveness is compared and validated with the other existing approaches.

Regulatory incentives for transmission system operators under flow-based market coupling

Flow-based market coupling is a critical element of the electricity market in Europe. Transmission System Operators determine the commercial transmission capacity that can be implicitly traded in a zonal day-ahead market. However, this entails a trade-off: higher commercial transmission capacities increase market efficiency, affecting the electricity market prices, but also increase redispatch costs, affecting the network tariff. The decision on the commercial transmission capacity should optimally balance day-ahead welfare and redispatch costs, but depends on the rules and regulated incentives enforced on the TSOs. A MinRAM criterion, i.e., imposing minima for the commercial transmission capacity, is a one-size-fits-all policy without variation in time and space that unlikely leads to optimal transmission capacity allocation and is hard to tune because regulators have incomplete information. Incentive regulation is an alternative policy instrument promoting welfare-maximizing commercial transmission capacities, robust against information asymmetry. We provide a set of mathematical conditions to properly design an incentive scheme that rewards price convergence and penalizes excessive redispatch costs. Therefore, this paper serves as a stepping stone towards tapping the full potential of cross-border trade in zonal markets for policymakers, regulators, TSOs and market participants.

Enhancing Automation with Label Defect Detection and Content Parsing Algorithms

The stable operation of power transmission and distribution is closely related to the overall performance and construction quality of circuit breakers. Focusing on circuit breakers as the research subject, we propose a machine vision method for automated defect detection, which can be applied in intelligent robots to improve detection efficiency, reduce costs, and address the issues related to performance and assembly quality. Based on the LeNet-5 convolutional neural network, a method for the detection of character defects on labels is proposed. This method is then combined with squeezing and excitation networks to achieve more precise classification with a feature graph mechanism. The experimental results show the accuracy of the LeNet-CB model can reach up to 99.75%, while the average time for single character detection is 17.9 milliseconds. Although the LeNet-SE model demonstrates certain limitations in handling some easily confused characters, it maintains an average accuracy of 98.95%. Through further optimization, a label content detection method based on the LSTM framework is constructed, with an average accuracy of 99.57%, and an average detection time of 84 milliseconds. Overall, the system meets the detection accuracy requirements and delivers a rapid response. making the results of this research a meaningful contribution to the practical foundation for ongoing improvements in robot intelligence and machine vision.

Compounding or Curative? Investigating the impact of electrolyzer deployment on congestion management in the German power grid

Integrating large amounts of hydrogen production capacities for decarbonizing energy-intensive industries in Germany can be challenging for transmission system operators. This research investigates interactions of hydrogen production deployment pathways and associated congestion management policies with the operation of the German electricity transmission system for future market projections. Hydrogen electrolysis imputes additional electricity loads above conventional levels. A scenario framework is created representing different geographic electrolyzer deployment pathways and congestion management regulations for electrolyzer operation. Fundamental electricity market modeling and load flow optimization are proposed to evaluate resulting congestion management volumes to resolve grid bottlenecks associated with the market clearing dispatch. Overall results of this work highlight the importance of designing congestion management frameworks that enable efficient utilization of electrolyzers as a redispatch capacity, primarily if a demand-oriented deployment of electrolyzer installations near energy-intensive industries is assumed to support renewable energy integration. Differences in congestion management cost between demand- and supply-oriented deployment pathways of electrolyzer capacity lie in the range of 0.77–0.97 bn Euro if electrolyzers cannot be redispatched but almost diminish to 0.10–0.21 bn Euro in the scenarios that include electrolyzer as a redispatch capacity. The findings of this work assist policymakers and regulators with valuable insights into design options for future congestion management frameworks.

Distributed Energy Resource and Energy Storage Investment for Enhancing Flexibility Under a TSO-DSO Coordination Framework

This paper presents a distributed energy resource and energy storage investment method under a coordination framework between transmission system operators (TSOs) and distribution system operators (DSOs), which simultaneously addresses two main aspects of the flexibility aggregation of DSOs, i.e., flexibility enhancement and dynamic flexibility provision. First, to characterize the key flexibility features of power distribution networks, a multi-port multi-period feasible region formulation is designed using the robust optimization conception while avoiding over-parameterized formulations that require extensive information exchange. Second, a two-stage robust planning model is built to enhance distribution system flexibility by maximizing the volume of feasible regions, in which the uncertainty of dispatch instructions is modeled as a decision-dependent uncertainty (DDU) set and the worst realization is identified for the operational security evaluation. The proposed two-stage robust planning model is solved via a customized column-and-constraint generation algorithm. Finally, a distributed framework for TSO-DSO coordination is proposed to enable the dynamic adjustment of feasible region provision of DSO, given the TSO’s preference, which is then solved by a DDU-based two-stage robust extension of the alternating direction method of multipliers algorithm. Numerical results verify the effectiveness of our proposed models and the scalability of the associated algorithm. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The increasing integration of renewable energy resources has stimulated the need for aggregated flexibility provided by power distribution networks (PDNs). However, there are three challenges: i) using the currently feasible region formulation of PDN requires extensive information exchange with the transmission system operator (TSO), thus not compatible with the current structure. ii) the optimal investment of various assets to leverage their cost-effectiveness in feasible region enhancement needs to be addressed. iii) lack of a proper coordination mechanism between TSO and distribution system operators (DSOs) to facilitate the optimal feasible region provision and leverage the spatiotemporal flexibility. To address the above challenges, we design an easy-to-implement feasible region formulation to characterize the key flexibility features of PDNs. Upon this, we propose a feasible region enhancement planning method based on an extended two-stage robust model to address the decision-dependent uncertainty. Furthermore, we facilitate the optimal feasible region provision through the TSO-DSO coordination process in a distributed manner. The numerical results show that the proposed planning method and coordination mechanism could effectively achieve optimal flexibility enhancement and dynamic flexibility provision. In practical application, our proposed planning method can be readily implemented with advanced analytical tools. The coordination mechanism is also compatible with the current TSO-DSO structure and can be easily integrated into it.

ANALYSIS OF METHODS TO INCREASE QOE PARAMETERS FOR VIDEO STREAMING SERVICES

Video streaming services represent a new generation of television (DTV), which have become an integral part of modern digital culture. With the development of Internet technologies and the spread of broadband access, video streaming has become a popular and convenient way to consume multimedia content. Unlike traditional television, video streaming services provide the user with the ability to choose content, watch it at a convenient time and on different devices, which leads to new challenges and opportunities in improving the quality of user experience (QoE). One of the key elements that determine the quality of a video streaming service is the operator's transmission equipment and platform servers. These components provide content streaming over the Internet and affect such parameters as download speed, data stream stability and playback quality. Efficient management and optimization of the transmission equipment and servers can reduce latency, improve video quality and provide smoother streaming of content to end users. This research project aims to analyze methods for improving QoE parameters for video streaming services to better understand how technologies, algorithms and strategies can be applied to optimise the user experience in this new type of digital content. By considering factors such as video quality, adaptive streaming, traffic management, and many others, we aim to highlight key aspects that contribute to improving QoE and providing a more satisfactory user experience in video streaming services.

Development of a simulation model for assessing the technical condition of the magnetic circuit of oil power transformers by measuring the temperature of the tank and the external environment

In the article, the authors analyzed how oil-filled power transformers ensure reliable and stable operation of power transmission systems by providing efficient transmission of electricity of different voltages. In the article, the authors found that the main elements of oil-filled power transformers - the magnetic circuit, the coil and the technical condition of the oil - directly determine the performance of oil-filled power transformers. In this work, a simulation model was developed to evaluate the magnetic circuit of power oil transformers based on the measured temperature of the tank and the external environment during express diagnosis. A simulation model has been developed that allows to calculate the technical condition of oil power transformers operating in city power networks. It is shown that the developed model allows to calculate the value of the technical condition of the oil power transformer with the help of diagnostic parameters. In order to represent the technical state of the magnetic circuit of the oil power transformer, the functions of changing the state value of the output variable in the Mamdani fuzzy logic method are shown and the block diagrams are drawn up. Author’s using the Mamdani fuzzy logic method, express diagnosis of the technical condition of the “Magnetic core of the oil power transformer” was carried out in the Matlab simulink program. During the evaluation, the value of the output parameter is taken from 0 to 100, and each step is divided by 10, the smallest value is 0, and the largest is 100.

Modeling and Rapid Prototyping of Integrated Transmission-Distribution OPF Formulations With PowerModelsITD.jl

Conventional electric power systems are composed of different unidirectional power flow stages of generation, transmission, and distribution, managed independently by transmission system and distribution system operators. However, as distribution systems increase in complexity due to the integration of distributed energy resources, coordination between transmission and distribution networks will be imperative for the optimal operation of the power grid. However, coupling models and formulations between transmission and distribution is non-trivial, in particular due to the common practice of modeling transmission systems as single-phase, and distribution systems as multi-conductor phase-unbalanced. To enable the rapid prototyping of power flow formulations, in particular in the modeling of the boundary conditions between these two seemingly incompatible data models, we introduce PowerModelsITD.jl, a free, open-source toolkit written in Julia for integrated transmission-distribution (ITD) optimization that leverages mature optimization libraries from the InfrastructureModels.jl-ecosystem. The primary objective of the proposed framework is to provide baseline implementations of steady-state ITD optimization problems, while providing a common platform for the evaluation of emerging formulations and optimization problems. In this work, we introduce the nonlinear formulations currently supported in PowerModelsITD.jl, which include AC-polar, AC-rectangular, current-voltage, and a linear network transportation model. Results are validated using combinations of IEEE transmission and distribution networks.

Vulnerability of the Load Frequency Control Against the Network Parameter Attack

By integrating the communication-enabled high-voltage electronic devices into the supervisory control and data acquisition (SCADA) system, the smart grid achieves flexible, economic, controllable operations of remote and real-time electricity transmission and distribution. However, it has been widely recognized that the SCADA system is vulnerable to unprecedented cyberattacks. In this paper, we propose a novel attack, namely, a network parameter attack (NPA), on the physical parameter of the branch to affect the load frequency control. The idea is to modify the control signal sent to the thyristor-controlled series compensator (TCSC) device to change the reactance of the transmission line, thus, inflicting the grid frequency stability. We first provide a sufficient condition for NPA to cause frequency instability. To further provide more insights, we analyze the impact of NPA on frequency stability based on the eigenvalue sensitivity. The vulnerable transmission lines are screened out based on the error caused by the NPA on the eigenvalues. Furthermore, we develop a least-effort but maximum-impact attack strategy considering the attacker’s limited resources. Finally, we conduct extensive simulations to validate the effectiveness of the attack and evaluate its impact on the system’s operation.

The European natural gas system through the lens of data platforms

European Union legislation obliges natural gas transmission system operators to publish key transport indicators on a transparency platform operated by the European Network of Gas Transmission System Operators for Gas (ENTSOG). Gas Infrastructure Europe (GIE) maintains similar transparency initiatives, providing data on the use of liquefied natural gas (LNG) terminals as well as underground gas storage facilities. These platforms have become a useful source of information for researchers, practitioners, and policy makers that is available to the general public at no cost. We demonstrate that these data platforms essentially represent an archive of the European natural gas system and how the security of supply situation of Europe can be monitored in almost real time by analyzing the evolution of flow patterns on a daily basis as well as longer time horizons. In particular, we show how the system has reacted to infrastructure expansions, disruptions, and an evolving geopolitical context.

Reinforcement-Learning-Based Proactive Control for Enabling Power Grid Resilience to Wildfire

Industrial electric power grid operation subject to an extreme event requires decision-making by human operators under stressful conditions. Decision making using system data informatics under adverse dynamic events, especially if forecasted, should be supplemented by intelligent proactive control. Power transmission system operation during wildfires requires resiliency-driven proactive control for load shedding, line switching, and resource allocation considering the dynamics of the wildfire and failure propagation to minimize the impact on the system. However, the possible number of line and load switching in an extensive industrial system during an event make traditional prediction-driven and stochastic approaches computationally intractable, leading operators to often use pre-planned or greedy algorithms. In this work, we model and solve the proactive control problem as a Markov decision process and introduce an integrated testbed for spatio-temporal wildfire propagation and proactive power-system operation. Our approach allows the controller to provide setpoints for all generation fleets in the power grid. We evaluate our approach utilizing the IEEE test system mapped onto a hypothetical terrain. Our results show that the proposed approach can help the operator to reduce load outage during an extreme event. It reduces power flow through lines that are to be de-energized, and adjusts the load demand by increasing power flow through other lines.

Драйвери сталого розвитку країн в умовах глобалізації

The article substantiates the drivers of sustainable development of countries in the context of globalization, namely: the development of alternative energy, low-carbon economy, circular economy. It is argued that with the establishment of the model of sustainable development in the world practice, the issue of a significant reduction in the segment of energy-intensive types of global production and a decrease in the scale of consumption of energy resources is of particular importance. It is substantiated that in order to disseminate an energy-efficient model of economic development on a global scale, it is necessary to form an active State policies of the countries of the world by creating economic, administrative, social and infrastructural conditions, eliminating State subsidies to environmentally harmful industries, using market incentives, increasing public procurement in energy-saving industries, along with stimulation of their investment financing. The prospects for the development of the world energy sector until 2030 are outlined. The synchronization of Ukraine with ENTSO-E, the European network of electricity transmission system operators, is examined. It is found that synchronization with ENTSO-E is a step towards expanding the opportunities and prospects for attracting investment in the energy sector of Ukraine. Recommendations on finding effective ways of transition of countries’ economies to the use of alternative energy sources, low-carbon development and application of the principles of circular economy (the conception of combining linear production lines into a closed cycle) are provided. It is substantiated that the transition to sustainable low-carbon development can be successful due to the implementation of the global energy conversion of the economy.

Algorithm for synthesis of plane gears according to the constant curvature criterion

This paper presents an algorithm for synthesizing plane gears based on the constant curvature criterion. The derived formulas for pinion gears can be applied in various mechanisms, including clockwork mechanisms, gun turret aiming systems, lifting and transport mechanisms, and planetary gearboxes with tracked propellers. These formulas enable effective analysis of transmission operation and optimal value selection, leading to more rational design and increased efficiency of the entire mechanism. Internal gearing technology allows for significant reductions in drive dimensions and metal consumption compared to traditional involute gears. Improving the technical characteristics of mechanical drives can be achieved by optimizing pinion gear design. This study focuses on the analysis of pinion gears, which reduce profile slippage and transmission wear, resulting in increased efficiency and convenience of operation. Additionally, pinion gears are technologically advanced and reliable. This work develops a mathematical model of a pinion transmission as a flat gearing with a constant gear ratio, providing a foundation for further research and practical applications.