Transmission System Operators Research Articles

Natural gas consumption estimation in the European Union

On 5 August 2022, the European Commission adopted the Regulation (EU) 2022/1369 on coordinated demand reduction measures for gas to decrease, on a voluntary basis, 15 % the gas consumption in the European Union (EU) over the period 1 August 2022 – 31 March 2023 compared to the previous five years. In 2023, the prolongation of this regulation was proposed until 31 March 2024 in order to save gas, facilitate the refilling of storages during the summer, and avoid exhaustion at the end of next winter. Thus, there is a need to monitor as closely as possible the natural gas consumption in the EU and keep track of the accumulated demand reduction for natural gas. However, the most up-to-date figures from the statistical office of the EU (Eurostat) are provided with a delay of one to two months and with coarse granularity (monthly). This paper (i) proposes a methodology to estimate the EU natural gas consumption with daily granularity, and (ii) presents two applications for monitoring the gas demand reduction with coarser granularity (weekly and monthly). The methodology, benchmark, and applications exclusively rely on publicly available sources such as Eurostat, the transparency platforms from the European Network of Transmission System Operators for Gas (ENTSOG), Gas Infrastructure Europe (GIE), as well as ENaGaD. ENaGaD is the in-house Joint Research Centre’s database of time series of natural gas consumption of the EU Member States.

A highly robust gas network simulation approach through an inherently solvable problem formulation for network states far from intended design points

Pipeline networks are an efficient and widespread transportation system for supplying natural gas as well as increasingly green gas to Europe. However, they are exposed to risks arising from environmental factors, accidents, crime and political issues. This work contributes to the assessment of gas transmission networks and enables a targeted improvement of their resilience. Therefore, the objective of this work is to develop a simulation tool that enables gas transmission system operators (TSOs) to identify weak spots, e.g. potential bottle necks, in their pipeline networks. To this end, a steady-state gas network simulation approach is developed that provides fast results for gas supply deficiencies for complete sets of multi-event disruption scenarios, enabling the identification of the most important network elements. This paper describes how to implement a computationally fast, numerically robust, and physically accurate gas network simulation and assessment tool. By solving mass and momentum balance equations, it accounts for key network elements such as flow control valves, pressure control valves, compressor stations, gas sources, and gas consumers. The central feature that distinguishes this approach from classical steady state solvers is the robustness of the gas flow calculation through the choice of a problem boundary condition formulation, which results in an inherently solvable system of equations. This feature is key in ensuring mathematical convergence of predictions for gas network states that strongly deviate from their original design point, where boundary conditions must not become mathematically invalid but need to reflect physically reasonable behavior. The capabilities of the system are demonstrated using a fictitious gas network and a representative national gas transmission network. Finally, the limits of applicability are outlined based on the size of the network under consideration and the types of analyses.

The 2015–2019 excavation of the bronze foundry site at the Huanbei Shang City in Anyang, Henan

Abstract The Anyang Team of Institute of Archaeology, Chinese Academy of Social Sciences conducted five excavations of a bronze foundry site at the Huanbei Shang City from 2015 to 2019. A variety of archaeological features were discovered, ranging from the foundation built from calcareous nodules and rammed earth, bronze melting and casting area, refuse area, sacrificial pit, ash pit, well, and cache pit. Many artifacts related to metallurgy were also unearthed, including clay molds, models, cores, bellow nozzles, slag, furnace fragments, charcoal, bone gravers, and whetstones. The discovery of this bronze foundry site is of great value for the study of the Huanbei Shang City layout, the operation, and management of bronze casting, technological transmission, and other questions. Bronze casting technology at Huanbei Shang City was still in its early stages of development, but it laid a solid foundation for the later flourishing of the bronze civilization at Yinxu.

Enhancing the transient stability of interconnected power systems by designing an adaptive fuzzy-based fractional order PID controller

The reliable and efficient operation of the electrical energy transmission system heavily relies on maintaining stability as a key requirement. Interconnected power systems often experience low-frequency oscillations (LFOs), which have the potential to initiate instability and, subsequently, necessitate careful attention and investigation. To tackle this issue, researchers have focused on various controllers, including Fractional-Order Proportional-Integral-Derivative (FOPID) controllers. The FOPID controller, with its increased number of design parameters, has proven to be more successful than the traditional PID controller in various engineering applications. However, determining the optimal parameters for the controller becomes more challenging due to the increased design space. Moreover, the performance of fixed-gain FOPID controllers may be degraded when confronted with highly nonlinear and uncertain controlled objects such as power systems. This issue is primarily attributed to the static nature of fixed-gain FOPID controllers. To overcome these challenges associated with fixed-gain FOPID controllers and to instill an adaptive quality, this article introduces a novel power system control methodology. This adaptive approach combines a FOPID control strategy with a fuzzy logic system and is denoted as EOA-AFFOPID. The proposed adaptive controller dynamically tunes its coefficients through a fuzzy block, which significantly improves the overall performance of the control system. To establish a performance benchmark, we have also created an alternative controller, named EOA-FOPID, a version of the optima FOPID controller with fixed coefficients. The proposed methodology is applied to multi-machine interconnected power systems equipped with Static Synchronous Series Compensators (SSSCs), and comparative evaluations are conducted with other popular recent control strategies. The comparisons demonstrate the effectiveness of the EOA-AFFOPID control strategy in damping system fluctuations and achieving significant performance improvements in terms of different metrics including overshoot, undershoot, and settling time.

Extreme Gradient Boosting Model for Day-Ahead STLF in National Level Power System: Estonia Case Study

Short-term power load forecasting refers to the use of load and weather information to forecast the Day-ahead load, which is very important for power dispatch and the establishment of the power spot market. In this manuscript, a comprehensive study on the frame of input data for electricity load forecasting is proposed based on the extreme gradient boosting algorithm. Periodicity was the first of the historical load data to be analyzed using discrete Fourier transform, autocorrelation function, and partial autocorrelation function to determine the key width of a sliding window for an optimization load feature. The mean absolute error (MAE) of the frame reached 52.04 using a boosting model with a 7-day width in the validation dataset. Second, the fusing of datetime variables and meteorological information factors was discussed in detail and determined how to best improve performance. The datetime variables were determined as a form of integer, sine–cosine pairs, and Boolean-type combinations, and the meteorological features were determined as a combination with 540 features from 15 sampled sites, which further decreased MAE to 44.32 in the validation dataset. Last, a training method for day-ahead forecasting was proposed to combine the Minkowski distance to determine the historical span. Under this framework, the performance has been significantly improved without any tuning for the boosting algorithm. The proposed method further decreased MAE to 37.84. Finally, the effectiveness of the proposed method is evaluated using a 200-day load dataset from the Estonian grid. The achieved MAE of 41.69 outperforms other baseline models, with MAE ranging from 65.03 to 104.05. This represents a significant improvement of 35.89% over the method currently employed by the European Network of Transmission System Operators for Electricity (ENTSO-E). The robustness of the proposal method can be also guaranteed with excellent performance in extreme weather and on special days.

OSAT Production Testing of 5G, Power Discretes & 3D packaged ICs

The presentation will be segmented into three. OSAT production testing challenges of three vital product families that are important to our semiconductor industry will be showcased in each segment. The first segment will describe the products and impacts to RF production testing of both Sub-8GHz carrier frequency range and the mmWave frequency range of operation. The second segment will explore emerging MOSFET technologies that enable faster switching rates and higher voltage and current topologies. The third segment will describe the challenges of production test content for 3D-stacked advanced packages. 5G RF has enabled mmWave carrier frequencies, small cell deployment, massive MIMO (Multiple In, Multiple Out), beam forming, and full duplex wireless transmission and reception operations. These features require new production test methodologies. There is an astronomical rise in battery powered applications like toys, consumer goods, automotive and trains. Power path turn on/off with MOSFETs is in the critical path. The technology has advanced from the traditional Si to GaN and SiC based products that have a smaller size and allow for higher application efficiencies. Test specifications and limits are improving and production testing methods are evolving to account for these changes. Advanced packaging has enabled the path to integrate chiplets within a single package. Heterogeneous Integration (HI) is a powerful design innovation that allows tighter integration and, in some cases, improved signal and power performance at the system level. Production test methodologies are being streamlined to make test a competitive advantage for our customers.

Blockchain based sustainable energy transition of a Virtual Power Plant: Conceptual framework design & experimental implementation

Sustainable frameworks are being introduced by technological breakthroughs to address the continuously increasing demand for energy and this article presents a novel framework for a Virtual Power Plants to sustain and optimize Distributed Energy Resources (DERs) administration through blockchain technology. The multi-layered architecture integrates blockchain technology with other VPP components, such as a cloud service provider, grid and transmission operator, and forecasting of DERs, to optimize bidding and scheduling in real-time across multiple markets to enhance energy efficiency and grid stability. By employing a system engineering methodology, this framework incorporates smart meters to facilitate the transmission and reception of data i.e., voltage, and current between participants, and DERs within the network. This strategy makes it easier to advance sustainable energy sources, which advances predictive capabilities, strengthens the framework’s resilience, and protects the environment. The investigation of demand response, functional and system trade-off analysis, configuration selection, and other subsystems within a decentralized network offers insights into the necessary components and challenges involved in the construction of such a system. This study contributes comprehensive assistance and valuable insights to both practitioners and researchers involved in the field of sustainable energy transition through Virtual Power Plant.

ADAPTIVE EDUCATIONAL MODELS OF ENERGY SYSTEMS

The article examines the need to use dispatching simulators for the training of operational personnel in the networks of the transmission system operator and the distribution system operator. Differences between types of educational models are studied. An

Experimenting with co-ownership of energy storage facilities - A case study of the Netherlands

This article discusses how shared ownership of energy storage facilities between grid managers (Distribution System Operators and Transmission System Operators) and third-party market participants may help to resolve congestion issues. The article uses the Netherlands as a case study on how congestion issues may lead to a stalemate: increasing energy storage capacity may help to resolve grid congestion but may cause additional congestion if used to trade in profitable markets. As a result, it is not installed, or installation is delayed until the grid is fortified. The article discusses how shared ownership may lead to the co-optimization of investment decisions by different stakeholders and of the operation of the storage facility. It also discusses how the exemption to unbundling obligations under art. 36 (2) of Directive 2019/944 can be used to allow for these ownership constructions. The article argues that national regulatory authorities can use regulatory experimentation to find the desirable conditions and uses of the exemption and to stimulate regulatory learning. The use of experimentation can help to resolve congestion issues in certain localities in the short term and help to develop principles for regulation of the future energy system in the long-term.

Log specification and intelligent analysis method based on oil and gas pipeline SCADA system

Abstract As the control center of the natural gas long-distance pipeline network, the SCADA system shoulders the important tasks of data collection and monitoring of the whole long-distance pipeline, gas transmission management, production scheduling, operation and maintenance coordination in production, and plays a very important role in the whole oil and gas pipeline. In this paper, firstly, the SCADA system for localized long-distance pipelines is explained in detail, including its basic structure and special solutions to problems. Secondly, the AdaBoost algorithm, which combines the MapReduce parallel computing framework, is introduced to collect and process data from the operation logs of the SCADA system and normalize the logs. Finally, to test the interaction between the improved AdaBoost algorithm and the SCADA system, a system test was conducted. The results show that the average latency of scheduling the logs of the SCADA system by AdaBoost algorithm with MapReduce parallel computing framework is only 39.82ms, the average processing speed of the log normalization file data under the multi-threaded mode of the system reaches 86.51GB/s, and the effective accuracy of the fault diagnosis is as high as 90.36%. This shows that the oil and gas pipeline SCADA system interacting with data visualization technology can process operation logs more quickly and can carry out real-time intelligent supervision of the working status and operation parameters of the whole auxiliary system, promoting the intelligent development of the oil and gas pipeline SCADA system.

Research on the Attack Strategy of Multifunctional Market Trading Oriented to Price

In the context of energy transformation and power market system reform, it is crucial to address the network risks associated with enhancing the integration of the “Energy–Information–Market” paradigm. This necessitates research on multi-energy market trading modes and the corresponding offensive and defensive technologies. This paper proposes a novel approach centered around a node-local Energy Hub (EH) that represents large industrial users with diverse energy demands. To facilitate multi-energy two-way trading, a price-oriented Transactive Energy (TE) market clearing strategy is developed. Building upon this transaction network framework, a data-driven attack strategy targeting the state estimator of the Transmission System Operator (TSO) is introduced and implemented in two stages, encompassing real-time topology estimation and False Data Injection attacks. By leveraging Matrix Transfer Entropy (MTE), the optimal attack target is identified to disrupt the economic stability of the system and the profit of the attacker increases significantly. The proposed attack strategy is validated through simulations conducted on a 30-node system, yielding conclusive evidence of its effectiveness while offering vital insights for system defense.

Analysis of the Implementation of Virtual Power Plants and Their Impacts on Electrical Systems

The increasing penetration of Distributed Energy Resources (DERs) in Distribution Systems (DSs) has motivated studies on Virtual Power Plants (VPPs). However, few studies have jointly assessed the sizing and economic attractiveness of VPPs from the entrepreneur’s perspective and the potential benefits and impacts on power systems while maintaining the scope to DSs. This study proposes a methodology for sizing VPPs and simulating their economic optimal dispatch and economic attractiveness with a focus on the entrepreneur’s viewpoint. In addition, it also evaluates VPPs’ potential benefits and impacts on a DS or Transmission System (TS) while considering the interface between the Distribution System Operator (DSO) and the Transmission System Operator (TSO). The methodology employs optimization to minimize the Net Present Cost (NPC) of the project, in relation to sizing the DERs, and to obtain the economic optimal dispatch of the BESSs that comprise the VPP. Moreover, a power flow analysis and probabilistic reliability assessment are used to evaluate the benefits and impacts on the power system. The methodology was applied to a case study involving Photovoltaic (PV) systems and Battery Energy Storage Systems (BESSs) used by aggregated medium voltage consumers, which configure Technical Virtual Power Plants (TVPPs) participating in Demand Response (DR) via incentives, with a network model of the Brazilian National Interconnected System (SIN) adapted from the 2030 Ten-Year Energy Expansion Plan (PDE) of the Energy Research Office (EPE), along with data from the Geographic Database of the Distribution Utility (BDGD). The results indicate the economic attractiveness of DERs according to the premises adopted and indicate improvements in TS reliability indexes with the possibility of TVPPs’ dispatch after transmission contingencies.

Design and Synthesis of Low Surface Energy Coating with Functionalized Al2O3 Nanoparticles.

In a high-moisture environment where dust and coastal saltwater are prevalent, the stability of power equipment can be adversely affected. This issue can result in equipment downtime, particularly for transformers, severely disrupting the continuous operation of DC transmission systems. To address this challenge, a superhydrophobic modified fluorosilicone coating was developed, incorporating anti-stain properties. To tackle this issue comprehensively, an orthogonal experiment was conducted, involving six factors and three levels. The study focused particularly on assessing the impact of water-repellent recovery agents, nanofillers, antistatic agents, anti-mold agents, leveling agents, as well as wetting and dispersing agents on the coating's surface tension. The results demonstrate that selecting an appropriate base resin and incorporating well-matched functional additives played a central role in effectively reducing the surface tension of the coating. Consequently, optimized coatings exhibited exceptional resistance to stains and displayed strong corrosion resistance.

Optimal combined wake and active power control of large‐scale wind farm considering available power

AbstractThe high‐order nonlinear complex characteristics of traditional static wake model (SWM) restrict the fast optimization of wake effect. Therefore, this paper introduces a dynamic wake model (DWM) to describe the time‐varying wake characteristics of wind turbines (WTs) with low computational cost. The traditional SWM is linearized to derive the wake wind speed sensitivity coefficients, which represents the sensitivity of wake wind speed deficit with respect to the active power reference. Considering the natural propagation characteristics of wake effect, a wake delay function is added to realize the future wind speed prediction of different locations of the wind farm. And a joint control strategy of wake and active power based on model predictive control (MPC) is proposed to optimize the power contribution of each WT to minimize wake effects, and maximize total available power. Thus, the increased available power is able to satisfy the power demand from Transmission System Operator (TSO) for ancillary services and enhance power support capability. The control performance of the proposed control strategy is evaluated by simulations under constant and varying incoming wind speed.

Electric vehicle charging as a source of nordic fast frequency reserve—proof of concept

AbstractDemand‐side flexibility or demand response (DR) has long been recognized as a potential source of balancing capacity. The charging of electric vehicles (EVs) is a known source of flexible capacity, and the vast amount of charging capacity available can be utilized for valuable applications, including ancillary power markets, by controlling the charging sessions according to the needs of the power system. One identified and unexplored potential market for EV DR capacity is the Fast Frequency Reserve (FFR) market for the Nordic system area. This article proposes and demonstrates that a home charger can participate in this extremely fast reacting ancillary service market with only software modifications made to the charger. The biggest challenge in the FFR market is the response time requirement for capacity activation. When a certain frequency limit is exceeded, the activation must happen within 0.7 s in the worst case. In this study, a laboratory test setup was constructed to test the capabilities of the FFR‐enabled EV charger. The tests were conducted by building a laboratory microgrid capable of changing the grid frequency. Additionally, an economic feasibility study was carried out to evaluate the business potential of the concept in Finland. The economic study included an analysis of the concept's potential with different levels of DR service availability. The laboratory tests demonstrated the FFR capabilities of the charger and as a final outcome of the research, the Norwegian transmission system operator (TSO) approved the tested charger as a type‐prequalified FFR‐providing entity. The economic study revealed that the approach has good business potential, primarily because of the almost non‐existent cost side even if the availability rate decreases significantly.

Reactive power management considering Transmission System Operator and Distribution System Operator coordination

The increasing integration of Distribution Energy Resources (DER) in the distribution system has brought the necessity of a change in grid management and also for better coordination between the Transmission System Operator (TSO) and the Distribution System Operator (DSO). This work proposes a reactive power management model to be used by DSOs, in which reactive power flexibility from DER, and also from On-Load Tap Changer (OLTC) transformers and capacitor banks are used to handle voltage problems that may arise in both transmission and distribution grids due to the uncertain production of Renewable Energy Sources (RES). Besides, it is proposed that the DSO may provide a service to the TSO, in which the latter requests a reactive power setpoint from the first one, in the TSO-DSO boundary. Adaptive robust optimization on an Alternating Current Optimal Power Flow (AC-OPF) is modelled, ensuring that the DSO receives a feasible solution and is able to manage congestion and voltage problems. The proposed model is compared with its stochastic equivalent to assess its strengths and drawbacks. To test and validate the proposed models, a 37-bus Medium Voltage (MV) distribution grid with high RES penetration is used. An important conclusion is that, though the robust model presents a safer solution than the stochastic model, the operator must be aware of the trade-off between the desired level of robustness and the expected operating cost.

Provision of ramp-rate limitation from distribution networks to transmission systems as preventive action towards frequency disturbances

The high proliferation of Converter-Interfaced Renewable Energy Sources (CIRES) poses several challenges to electric power system operators regarding frequency stability and control. Some of these issues are related with the high active power Ramp Rates (RRs) of CIRES, stemming from their inertia-less and stochastic nature. To deal with such problems, Transmission System Operators (TSOs) often commit excessive amounts of conventional spinning reserves, while in weak Transmission Systems (TSs) regulations are imposed, aiming to mitigate RRs of CIRES. Moreover, several technical studies have proposed control approaches for RR Limitation (RRL). Nevertheless, the influence of RRL on frequency quality and mainly the impact of RRL control capability of small-scale CIRES, connected to Distribution Networks (DNs), on frequency deviations have not been fully explored and quantified. To fill this gap, a detailed investigation is performed in this paper. For this purpose, simulations are conducted on a simplified System Frequency Response (SFR) model as well as on an analytical power system model. The latter is a modified version of the IEEE 9-bus Test System, consisting of three conventional Synchronous Generators (SGs) and three Medium Voltage (MV) DNs, which include CIRES equipped with SuperCapacitors (SCs), thus presenting RRL control capability. To thoroughly evaluate the impact of RRL on frequency dynamics, a set of metrics is introduced and frequency duration curves are created for various scenarios. Finally, the influence of several factors, such as the total system inertia, the RRL target value, the SC size, etc, is quantified by using the proposed indices.

The economic impacts of integrating European balancing markets: The case of the newly installed aFRR energy market-coupling platform PICASSO

The coupling of European balancing markets is one of the latest steps towards integrating Europe’s internal electricity market. From mid-2022 onwards, besides imbalance netting, the activation of the automated frequency restoration reserves (aFRR) has also been increasingly integrated between European transmission system operators (TSOs) in the so-called PICASSO framework. The possible benefits of this balancing market integration include cost savings and a reduced use of activation energy.The goal of this paper is to quantify the effects of the joint activation of balancing power in European markets in terms of welfare gains and increases in consumer rents due to lower prices. The paper also aims to demonstrate the reduced use of activation energy under the latest market-coordination framework. For this purpose, the coupling of aFRR markets is modelled by formulating and solving the optimisation problems for economic activation using linear programming. A PICASSO market structure with imbalance netting and cross-border activation of reserves is compared to the non-collaborative reference arrangement and to the existing IGCC set-up with imbalance netting only. A case study of the Belgian, Dutch and German electricity systems is modelled over a full year using historic data from 2021. The study indicates overall welfare gains of €400 million per year, the same order of magnitude as the increase in economic welfare of earlier balancing platforms such as TERRE. In addition, the cross-border effects on activation volumes and prices and their distributional effects are discussed. The results suggest that within the three countries, the primary beneficiaries of PICASSO are balancing service providers in the Netherlands and Belgium, and consumers in Germany.

Grid supply point operations with TSO-DSO interaction: A comprehensive assessment of operating voltage feasibility

The feasible operating voltage at grid supply point is significantly affected by the high level of distributed energy resources (DERs) integration. However, while the operating voltage is typically defined by the transmission system operator (TSO), often the integration of DERs at specific nodes within the distribution system is not taken into account. This oversight can lead to security issue for the distribution system operator (DSO). Addressing this critical gap, this manuscript offers an in-depth analysis of voltage feasibility at the grid supply point. The TSO-DSO interaction has been utilized to estimate the revised limits of voltage, and the influence of several factors such as the level of DER integration, associated flexibility cost, system's demand level, and regulation of the reactive-to-active power ratio (Q/P) has been highlighted. For this, IEEE 9 bus system for TSO and 33 bus for DSO, are considered to estimate the balance condition between them. The revised voltage limits are estimated on DSO’s 33-bus system. The study shows that DER integration reduces voltage range at the transmission-distribution (T-D) interface. However, high DER integration increases the feasible voltage range by enhancing flexibility. Cost willingness and activation cost widen the voltage range with minimal impact during peak load, while demand levels affect limits throughout the operation window. Furthermore, Q/P regulations have the potential to expand the feasible voltage range.

Plausibility and Implications of Converter-Driven Oscillations Induced by Unstable Long-Term Dynamics

For decades, synchronous generators have dominated power system dynamics and have been the foundation for the comprehension of the physical phenomena involved in power system stability. This paradigm is rapidly changing; large synchronous generators that contribute to system strength are being replaced by inverter-based generators. Consequently, new kinds of instabilities are emerging. Slow-interaction converter-driven instability is one example in which undamped oscillations occur when inverter-based generators operate in weak areas. Transmission system operators have observed the phenomenon under the scope of short-term dynamics following a disturbance during a weak operating condition. This paper suggests that converter-driven oscillations can occur even in the case when the system's initial operating condition is strong. It concludes that the phenomenon can be triggered by long-term dynamics that slowly weaken the system in which small-signal and short-term simulations show an ample stability margin. The outcome is a combination of unstable long-term dynamics and undamped oscillations. Furthermore, this work suggests that classical emergency controllers that are effective against long-term instability may not be successful if undamped oscillations are also present. A method for instability detection and counteraction is proposed based on Prony analysis and time-domain simulations on the IEEE test system for voltage stability assessment.