Interconnected Electric System Research Articles

Evaluation of primary frequency regulation in Dominican Republic mine using scooptrams and electric trucks as battery storage systems

The use of electric vehicles in the mining sector aligns with the growing demand for tools that reduce energy consumption in productive processes. This study investigates how electric mining vehicles with vehicle-to-grid (V2G) technology can be integrated into power grids to improve system stability and frequency regulation. In the context of mining operations and the provision of auxiliary services (such as primary frequency regulation) to an interconnected electrical system, a regulatory framework that enables V2G integration should be established. This issue is addressed through a case study involving DIgSILENT PowerFactory simulations. The goal is to evaluate the productive process of a mine and the contribution of V2G technology to the primary frequency regulation of the electrical system under different scooptram integration parameters and battery electric trucks. This study also explores the challenges of V2G implementation in the absence of a regulatory framework. Different configurations of electric scooptrams and shovel that can affect frequency regulation are assessed. The obtained optimal configuration involves two truck loaders and three shovel loaders; the capacity of the current electrical infrastructure can support this configuration without affecting the capacity of the mine's electrical system. The simulations verify that applying V2G technology to mining vehicles helps stabilise the frequency of electrical systems and reduces the probability of component failure.

A Distributed Market-clearing Framework for Highly Interconnected Electricity and Gas Systems

A Distributed Market-clearing Framework for Highly Interconnected Electricity and Gas Systems

Experimental evaluation of conducted disturbances induced during high frequency switching of active components

Introduction. Power electronics devices are among the most widely used equipment in all fields. The increasing performance of these devices makes their electromagnetic interference factor very important. On the other hand, electromagnetic compatibility research is more and more interested in studies on the sources of electromagnetic disturbances, their propagation paths and the methods of reducing these electromagnetic disturbances. The purpose is to study the behavior of the various active power components at high frequency as well as the evaluation of their electromagnetic noise by using simulation and experimental measurement. Methods. In first time, the simulation was realized with the Lt-spice software which presents many advantages in its use and we validate in the second time the results obtained with experimental measurements. We start by study of the behavior of the diode, then the behavior of MOSFET transistor and finally the study of the behavior of the IGBT transistor. Results. All the simulations were performed using the Lt-spice software and the results obtained are validated by experimental measurements performed in the APELEC Laboratory at the University of Sidi Bel-Abbes in Algeria. The waveforms of the current and voltage across each component during its opening are presented. The results of the simulations are compared and validated with the realized measurements in order to better present the influence of the fast switching of semiconductors on the electrical quantities, which causes electromagnetic disturbances in the interconnected electrical system.

Development a Low-Cost Wireless Smart Meter with Power Quality Measurement for Smart Grid Applications.

Developing a low-cost wireless energy meter with power quality measurements for smart grid applications represents a significant advance in efficient and accurate electric energy monitoring. In increasingly complex and interconnected electric systems, this device will be essential for a wide range of applications, such as smart grids, by introducing a real-time energy monitoring system. In light of this, smart meters can offer greater opportunities for sustainable and efficient energy use and improve the utilization of energy sources, especially those that are nonrenewable. According to the 2020 International Energy Agency (IEA) report, nonrenewable energy sources represent 65% of the global supply chain. The smart meter developed in this work is based on the ESP32 microcontroller and easily accessible components since it includes a user-friendly development platform that offers a cost-effective solution while ensuring reliable performance. The main objective of developing the smart meters was to enhance the software and simplify the hardware. Unlike traditional meters that calculate electrical parameters by means of complex circuits in hardware, this project performed the calculations directly on the microcontroller. This procedure reduced the complexity of the hardware by simplifying the meter design. Owing to the high-performance processing capability of the microcontroller, efficient and accurate calculations of electrical parameters could be achieved without the need for additional circuits. This software-driven approach with simplified hardware led to benefits, such as reduced production costs, lower energy consumption, and a meter with improved accuracy, as well as updates on flexibility. Furthermore, the integrated wireless connectivity in the microcontroller enables the collected data to be transmitted to remote monitoring systems for later analysis. The innovative feature of this smart meter lies in the fact that it has readily available components, along with the ESP32 chip, which results in a low-cost smart meter with performance that is comparable to other meters available on the market. Moreover, it is has the capacity to incorporate IoT and artificial intelligence applications. The developed smart meter is cost effective and energy efficient, and offers benefits with regard to flexibility, and thus represents an innovative, efficient, and versatile solution for smart grid applications.

Grid-supported electrolytic hydrogen production: Cost and climate impact using dynamic emission factors

Hydrogen production based on a combination of intermittent renewables and grid electricity is a promising approach for reducing emissions in hard-to-decarbonise sectors at lower costs. However, for such a configuration to provide climate benefits it is crucial to ensure that the grid electricity consumed in the process is derived from low-carbon sources. This paper examined the use of hourly grid emission factors (EFs) to more accurately determine the short-term climate impact of dynamically operated electrolysers. A model of the interconnected northern European electricity system was developed and used to calculate average grid-mix and marginal EFs for the four bidding zones in Sweden. Operating a 10 MW electrolyser using a combination of onshore wind and grid electricity was found to decrease the levelised cost of hydrogen (LCOH) to 2.40–3.63 €/kgH2 compared with 4.68 €/kgH2 for wind-only operation. A trade-off between LCOH and short-term climate impact was revealed as specific marginal emissions could exceed 20 kgCO2eq/kgH2 at minimum LCOH. Both an emission-minimising operating strategy and an increased wind-to-electrolyser ratio was found to manage this trade-off by enabling simultaneous cost and emission reductions, lowering the marginal carbon abatement cost (CAC) from 276.8 €/tCO2eq for wind-only operation to a minimum of 222.7 and 119.3 €/tCO2eq respectively. Both EF and LCOH variations were also identified between the bidding zones but with no notable impact on the marginal CAC. When using average grid-mix emission factors, the climate impact was low and the CAC could be reduced to 71.3–200.0 €/tCO2eq. In relation to proposed EU policy it was demonstrated that abiding by hourly renewable temporal matching principles could ensure low marginal emissions at current levels of fossil fuels in the electricity mix.

Development of a Short-Term Electrical Load Forecasting in Disaggregated Levels Using a Hybrid Modified Fuzzy-ARTMAP Strategy

In recent years, electrical systems have evolved, creating uncertainties in short-term economic dispatch programming due to demand fluctuations from self-generating companies. This paper proposes a flexible Machine Learning (ML) approach to address electrical load forecasting at various levels of disaggregation in the Peruvian Interconnected Electrical System (SEIN). The novelty of this approach includes utilizing meteorological data for training, employing an adaptable methodology with easily modifiable internal parameters, achieving low computational cost, and demonstrating high performance in terms of MAPE. The methodology combines modified Fuzzy ARTMAP Neural Network (FAMM) and hybrid Support Vector Machine FAMM (SVMFAMM) methods in a parallel process, using data decomposition through the Wavelet filter db20. Experimental results show that the proposed approach outperforms state-of-the-art models in predicting accuracy across different time intervals.

The cost dynamics of hydrogen supply in future energy systems – A techno-economic study

This work aims to investigate the time-resolved cost of electrolytic hydrogen in a future climate-neutral electricity system with high shares of variable renewable electricity generation in which hydrogen is used in the industry and transport sectors, as well as for time-shifting electricity generation. The work applies a techno-economic optimization model, which incorporates both exogenous (industry and transport) and endogenous (time-shifting of electricity generation) hydrogen demands, to elucidate the parameters that affect the cost of hydrogen.The results highlight that several parameters influence the cost of hydrogen. The strongest influential parameter is the cost of electricity. Also important are cost-optimal dimensioning of the electrolyzer and hydrogen storage capacities, as these capacities during certain periods limit hydrogen production, thereby setting the marginal cost of hydrogen. Another decisive factor is the nature of the hydrogen demand, whereby flexibility in the hydrogen demand can reduce the cost of supplying hydrogen, given that the demand can be shifted in time.In addition, the modeling shows that time-shifting electricity generation via hydrogen production, with subsequent reconversion back to electricity, plays an important in the climate-neutral electricity system investigated, decreasing the average electricity cost by 2%–16%. Furthermore, as expected, the results show that the cost of hydrogen from an off-grid, island-mode-operated industry is more expensive than the cost of hydrogen from all scenarios with a fully interconnected electricity system.

OSeMOSYS Global, an open-source, open data global electricity system model generator

This paper describes OSeMOSYS Global, an open-source, open-data model generator for creating global electricity system models for an active global modelling community. This version of the model generator is freely available and can be used to create interconnected electricity system models for both the entire globe and for any geographically diverse subset of the globe. Compared to other existing global models, OSeMOSYS Global allows for full user flexibility in determining the time slice structure and geographic scope of the model and datasets, and is built using the widely used fully open-source OSeMOSYS energy system model. This paper describes the data sources, structure and use of OSeMOSYS Global, and provides illustrative workflow results.

Reliability standards and generation adequacy assessments for interconnected electricity systems

This paper studies the consistency between two contradictory policies in the electricity industry. On the one hand, electricity systems are increasingly interconnected. On the other hand, reliability standards, whose value was typically set when countries were hardly interconnected, are still enforced at the national level. We show that enforcing autarky reliability standards may still reach the welfare optimum in the presence of interconnections, but only under two conditions. First, installed generation capacities should be determined jointly, while considering the whole power system. Second, reliability calculations should fully internalize external adequacy benefits occurring in neighboring systems. We run a numerical application for a set of European countries and find that existing interconnections may lead to generation adequacy benefits of around one billion euros per year, by enabling a 18.9 GW decrease in generation capacity. In our case study, regional coordination is found to be more important than fully internalizing external reliability benefits in adequacy simulations.

Seismic performance of UHV composite post electrical equipment interconnected using a rigid bus with a sliding fitting

To evaluate the influence of a rigid bus on the interconnected post electrical equipment with a sliding fitting, this article conducted shaking table tests on two full-scaled ±800 kV ultra-high voltage post insulators. Simplifying the rigid bus with a sliding fitting serving as a linear spring and damper allowed us to create a dynamic model of the stand-alone insulators and establish advanced two-piece interconnected post electrical equipment. Later, parametric analyses were carried out on the dynamic model. The results showed that the frequencies of the interconnected system were similar to those of the stand-alone counterparts if the dynamic characteristics of the two interconnected items were similar. The seismic responses of the interconnected system generally decrease compared with those of the stand-alone insulators. Thus, the seismic performance of the rigid bus interconnected electrical equipment system could qualify as having a stand-alone status if the dynamic characteristics of the equipment items are similar. The connection stiffness greatly affects the seismic responses of UHV composite post electrical equipment.

Optimal scheduling of bidirectional coupled electricity-natural gas systems based on multi-port gas network equivalent model

Electricity and natural gas are combined in many technological fields such as gas-fired generation and power-to-gas. However, the information set is not fully shared between the operators of electricity system and natural gas system. When the natural gas network model is unknown and the measurement information is insufficient, assessing the state of the gas network is crucial for the reliable and efficient operation of interconnected electricity and natural gas system (IEGS). In order to solve this problem, this paper investigates an optimal scheduling method based on a multi-port gas network equivalent model, which is extracted from the real-time monitoring information. Firstly, Taylor's expansion is used to approximate the non-linear pipeline network Weymouth flow equation. Then use the matrix form to model the natural gas network with non-pipe elements. On the basis of this model, the multiple linear regression equivalent model is derived to represent the multi-port gas network. Finally, based on the established gas network equivalent model, a two-way IEGS optimized scheduling strategy is proposed to minimize system operating costs and carbon emissions. The results show that the complexity of the model is significantly reduced without reducing the accuracy and robustness.

Cross-country spillovers of renewable energy promotion—The case of Germany

Electricity generation based on renewable energy (RE) sources such as wind and solar replace the most expensive generators that often rely on fossil fuels. In response to RE promotion, wholesale electricity prices and carbon emissions are therefore expected to decrease. In interconnected electricity systems, this so-called merit-order effect stimulates a change in electricity trade flows. Therefore, conventional generation and prices in neighboring countries are also likely to decrease. The impact of these trade reactions on carbon offsets is ambiguous and depends on installed generation and interconnector capacities. Moreover, the cross-border merit-order effect causes opposing effects on consumers and producers: generators’ profits decline, while consumers benefit from lower electricity costs and an increase in the consumer surplus. Using a rich data set of hourly technology-specific generation and wholesale market price data for ten central European countries, we estimate the domestic and cross-border impacts of German RE for the years 2015–2020. We find that German RE generation offset 79–113 MtCO2 per year. The major emission effect took place in Germany (64–99 MtCO2). The average cost of emission offset of 212–321€/t were almost entirely borne by German market participants. Neighboring countries do not bear costs, but a significant shift from producer to consumer rents is observed.

Reliability Standards and Generation Adequacy Assessments for Interconnected Electricity Systems

Reliability Standards and Generation Adequacy Assessments for Interconnected Electricity Systems

Reduction of operational restrictions of the transmission system in electrical systems through facts implementation

Operational constraints cause an increase in complexity, operating cost, and environmental and socioeconomic impact on electrical systems; operational constraints can be due to power flow, voltage, or frequency deviations. These restrictions force the grid operator to perform unplanned actions. This article identifies the various Alternating Current Flexible Transmission Systems (FACTS) devices with their characteristics, attributes, and implementation methods to lessen operating constraints on isolated and relatively small transmission systems with frequent power flow limit violations and voltage deviations. The case study is carried out in the National Interconnected Electric System (SENI) of the Dominican Republic, where the Fast Stability Voltage Index is used as an indicator to see the impact of the implementation of FACT to mitigate the operational restrictions of the electric system. Simulations are performed in the PowerFactory DIgSILENT software to obtain the results when modeling the interconnected FACTS devices on the transmission lines. The use of FACTS reduces the loadability of transmission lines, which is an essential factor in the emergence of power flow control and voltage constraints in isolated power systems.

GROUNDING METHODOLOGY IN A 550 kV AC POWER TRANSMISSION LINE IN THE AMAZON - A CASE STUDY

Atmospheric discharges are indispensable for the electrical sector due to their responsibility on the shutdown of the power lines, what may trigger a sequence of events that led the interconnected electrical system to collapse. The aim of this case study is to demonstrate the development of a viable methodology in order to reduce the resistance values of the grounding system of the power lines, reducing shutdown occurrences due to returning disruptive discharges, or backflashover, mitigating the damages caused to the electrical system and to society, in order to improve the quality of the electrical power distribution. Considering the factors of implementation costs, technical environmental viability, the encompassment of this solution for other structures lines, and the reduction of the implementation percentage, it was concluded that the most adequate solution to implement a more robust grounding system in the transmission power lines is the solution 03 tested on the tower 585, with a reduction of 66,98%.

Automated Generation Control of Multiple-Area Electrical System with an Availability-Based Tariff Pricing Scheme Regulated by Whale Optimized Fuzzy PID Controller

In this research, a whale-optimized fuzzy PID controller was developed to manage automatic generation control in multiple-area electrical energy systems with an availability-based tariff (ABT) pricing scheme. The objective of this work is to minimize the power production costs, area control errors (ACEs), and marginal costs of the multiple-area electrical energy system with real-time load and frequency variation conditions. The generation of power, deviation of power in the tie line, and deviation of frequency of the interconnected three-area electrical energy system, including the hydrothermal steam power plant and gas power plant, will be measured and analyzed rigorously. Based on the output from the whale optimization, the fuzzy PID controller regulates the deviation of power in the tie line and the deviation of frequency of the interconnected three-area electrical energy system. The reliability and suitability of the proposed optimization, i.e., whale-optimized fuzzy PID controller, are investigated against already presented methods such as particle swarm optimization and genetic algorithms.

Methodology for improvement protection systems performance associated to overhead lines

Power systems are permanently with failures risk, caused by electrical faults, human mistakes, harmonic component, flickers, among others. At the operational level, the impact of the incorrect operations of the Protection Systems in faults clearing has been documented, different studies cases of electrical failures not detected or not desired in a timely manner, they have led to the disconnection of the load of entire regions and even the total collapse of an electrical system. The foregoing is evident that the adequate selection of protection systems favors the reliable and safety operation of the grid. This paper introduces a novel methodology for the selection of protection systems for transmission lines, in the Peruvian National Interconnected Electric System. This methodology was structured for the revision of regulatory parameters related to the characteristics and performance of the protection systems and the technical aspects such as the redundancy of the protection system, the SIR estimation (source impedance ratio) and critical fault clearance times. Finally, the methodology studied in the Expansion Plan for Peru for the years 2019-2028, by means of electrical analysis, which allowed determining the way to have the characteristics of the protection systems of the new national grid expansion projects.

A power optimization model for the long‐term planning scenarios: Case study of Mexico's power system decarbonization

AbstractMexico is committed to reducing its CO2 emissions according to the Paris Agreement. A relevant effort must be made for the analysis of Mexico's electric energy system towards a progressive decarbonization with a larger participation of intermittent renewable energies. The analysis of power planning scenarios, with different assumptions on costs, emissions, and intermittent performance of the power generating technologies, is needed to make sustainable decisions in the transition toward a cleaner power sector. Tools for energy modelling are required to develop and analyze scenarios with minimum costs subject to environmental constraints. The purpose of the article is to explain the modelling approach of a novel and flexible power planning tool, which is based on a well‐known linear programming optimization method combined with a computing strategy to optimize time consumed for reading, processing calculations, and writing the huge number of economic and technical parameters required for the hourly power dispatch in complex interconnected electric systems. The time consumed has been optimized by means of a binary matrix that activates the input and use of only the data needed for the solution of the problem. The paper describes the MC model and demonstrates some of its analytical capabilities through a Mexican case study with a least cost scenario and two decarbonization scenarios of the power interconnected system for the period from 2020‐2050.

Cross-country Spillovers of Renewable Energy Promotion – The Case of Germany

Electricity generation based on renewable energy (RE) sources such as wind and solar replace the most expensive generators that often rely on fossil fuels. In response to RE promotion, wholesale electricity prices and carbon emissions are therefore expected to decrease. In interconnected electricity systems, this so-called merit- order effect stimulates a change in electricity trade ows. Therefore, conventional generation and prices in neighboring countries are also likely to decrease. The impact of these trade reactions on carbon offsets is ambiguous and depends on installed generation and interconnector capacities. Moreover, the cross-border merit-order effect causes opposing effects on consumers and producers: Generators' profits decline, while consumers benefit from lower electricity costs and an increase in the consumer surplus. Using a rich data set of hourly technology-specific generation and wholesale market price data for ten central European countries, we estimate the domestic and cross-border impacts of German RE for the years 2015 to 2020. We find that German RE generation offset 79 to 113 MtCO2 per year. The major emission effect took place in Germany (64 - 99 MtCO2). The average cost of emission offset of 212 to 321e/t were almost entirely borne by German market participants. Neighboring countries do not bear costs, but a significant shift from producer to consumer rents is observed.

An Improved Algorithm for AC Impedance Extraction

The overall system stability of interconnected electrical and electronic systems is associated with the input and output impedances of each individual system, therefore, accurate AC impedance measurement for a linear and nonlinear systems are imperative. These impedances are normally measured using small-signal frequency injection techniques. However, the harmonic transfers from the output side to the input side and vice versa deteriorates the measured results, making them ambiguous. These harmonic transfers cause the problems of frequency aliasing as well as spectral leakages leading to inaccurate measurements of results. In order to achieve the precise and accurate results, there is a need to adopt such an impedance measuring technique which is the best among the available techniques. A new algorithm is proposed to modify the range of frequencies of interest and inject such small-signal frequencies which do not interfere with the system harmonics. The measurement of the AC impedance of the three-phase RL circuit utilizing three different small-signal injection techniques is performed. From the results displayed, it is clear that all the techniques perform well, therefore, the most simple, single phase line-current injection was selected for the AC impedance measurement of the nonlinear switching circuit such as six-pulse rectifier. The issues discussed above are more serious in nonlinear switching circuit because of the presence of higher order switching harmonics in the circuit. The proposed algorithm is applied to measure the output-impedance of the three-phase AC power supply as well as the AC input-impedance of the six-pulse rectifier. These results of the switch vs average model and that of average model vs. experimental prototype are displayed for comparison, and it is clear that the proposed algorithm offers much-improved results.