Inter-regional Transmission Research Articles

Humidity Diffusion Process Analysis and Life Prediction of a VSC-HVDC Control Protection Device Based on a Finite Element Simulation Method

Voltage Source Converter-based High-Voltage Direct Current Transmission (VSC-HVDC) is essential for integrating renewable energy sources and facilitating inter-regional power transmission. This study evaluates the reliability of control and protection devices within these systems, which are crucial for the stable operation of power grids. Humidity significantly affects both the operational conditions and lifespan of these devices. Previous studies, reliant on extensive full-condition fatigue testing, have lacked effective test models and detailed analyses of mechanisms. To address this gap, a humidity diffusion model was developed to comprehensively investigate moisture diffusion mechanisms. Using the insights gained, the Hallberg–Peck model was applied to predict the lifespan of these devices, quantitatively assessing how changes in humidity affect their reliability. This approach employs a stringent failure criterion, leading to a conservative predicted lifespan. This method achieved a prediction accuracy of 85.648% compared to the benchmarks in GB/T 2423.50-2012, validating the accuracy of our model and the effectiveness of our simulation technology under stringent conditions. This research provides vital theoretical data and serves as an essential tool for guiding the precise maintenance of equipment in varying environmental humidity levels.

Nanopore sequencing of influenza A and B in Oxfordshire and the United Kingdom, 2022–23

We evaluated Nanopore sequencing for influenza surveillance. Influenza A and B PCR-positive samples from hospital patients in Oxfordshire, UK, and a UK-wide population survey from winter 2022-23 underwent Nanopore sequencing following targeted rt-PCR amplification. From 941 infections, successful sequencing was achieved in 292/388(75%) available Oxfordshire samples: 231(79%) A/H3N2, 53(18%) A/H1N1, and 8(3%) B/Victoria and in 53/113(47%) UK-wide samples. Sequencing was more successful at lower Ct values. Most same-sample replicate sequences had identical haemagglutinin segments (124/141, 88%); 36/39(92%) Illumina vs. Nanopore comparisons were identical, and 3(8%) differed by 1 variant. Comparison of Oxfordshire and UK-wide sequences showed frequent inter-regional transmission. Infections were closely-related to 2022-23 vaccine strains. Only one sample had a neuraminidase inhibitor resistance mutation. 849/941(90%) Oxfordshire infections were community-acquired. 63/88(72%) potentially healthcare-associated cases shared a hospital ward with ≥1 known infectious case. 33 epidemiologically-plausible transmission links had sequencing data for both source and recipient: 8 were within ≤5 SNPs, of these, 5(63%) involved potential sources that were also hospital-acquired. Nanopore influenza sequencing was reproducible and antiviral resistance rare. Inter-regional transmission was common; most infections were genomically similar. Hospital-acquired infections are likely an important source of nosocomial transmission and should be prioritised for infection prevention and control.

Assessing and enhancing the regional sustainability of electricity generation technologies in an energy-importing megaregion in China

Decision-makers are increasingly concerned about the sustainability of power generation technologies to achieve a secure and sustainable electricity supply in the future. This study aims to assess the sustainability of the eight key electricity generation technologies in the energy-importing Yangtze River Delta region of China and further enhance the regional sustainability of the electricity generation mix. We employed the multi-criteria decision-making process to rank the sustainability of the eight electricity generation technologiesfrom the perspective of various decision-makers. First, the results revealed that no technology is absolutely most sustainable. Second, the subjective findings show that hydropower is the most sustainable technology among the assessed ones, followed by nuclear and onshore wind power. Third, policymakers regard fossil fuel energy as more sustainable than investors and experts. Furthermore, local renewable diffusion and substantial electricity imports from renewable-rich areas can enhance the sustainability of the localelectricity system. In addition,an interregional electricity transmission grid with the neighbor Anhui province as the primary backup power supplier can sufficiently enhance the sustainability of the electricity system in the Yangtze River Delta region.

Assessing the carbon emission reduction effect of flexibility option for integrating variable renewable energy

Integrating a high-penetration level of variable renewable energy into power systems requires the pro-rata deployment of flexibility technology in the recent trends of low-carbon transition. This study proposes a multi-regional power system optimization model to assess the carbon emission reduction effect of different flexibility options in the Chinese power sector, including total carbon emissions, peaking timetables and values, carbon emission transfer between regional power systems, and carbon emission source changes between technologies. The results reveal that the combinations of dispatchable generation, inter-regional transmission, energy storage, and demand-side response can significantly reduce carbon emissions from power systems, but will lead to higher expenditure. Carbon emissions would peak 1–6 years in advance under the integrated flexibility option consisting of all flexibility technologies, and the corresponding peaking value would decrease by 0.26–0.48 billion tonnes compared to other configuration scenarios. However, this does not apply to all the regions. The coupling relationship between the flexibility option and carbon emission reduction in regional power systems changes with the disparities in power demand, system structure, and renewable energy consumption targets.

Coal Control and Carbon Reduction Path in Henan Province's Power Industry Under the Carbon Peak and Neutralization Target: A Medium- and Long-term Study

Achieving peak carbon dioxide emissions and accelerating decarbonization progress in the power industry is of paramount significance to Henan Province's objective of achieving carbon peak and neutrality. In this study, the Carbon Emission-Energy Integrated Model (iCEM) was employed to conduct scenario studies on the coal reduction and carbon reduction paths under the "dual-carbon" goal of Henan's power industry. The results indicated that, by considering measures such as optimizing the power source structure and technological progress, Henan Province's power industry carbon emissions will reach their peak between 2028-2033, with coal consumption in the power industry continuing to grow during the "14th Five-Year Plan" period. With a peak range between 2027-2031, the peak value increased by 1881, 1592, and 11.48 million tce, respectively, compared with that in 2020. To control coal in Henan Province under the constraint of carbon peak goals, it is proposed to develop clean energy sources such as wind and solar power, use more low-carbon or zero-carbon heat sources, increase the proportion of external electricity supply, and enhance energy-saving transformation in coal-fired power plants. Accelerating the elimination of backward units and energy-saving transformation of existing units, accelerating non-fossil energy development, advanced planning for external electricity supply, improving market mechanisms for the exit of coal-fired power plants and peak regulation, increasing system flexibility, and accelerating external policies to ensure clean energy security are effective paths for controlling coal and reducing carbon emissions in Henan's power industry. Additionally, inland nuclear power layout is one of the crucial paths to alleviate coal control pressure in Henan Province and achieve "dual-carbon" goals during the carbon-neutral stage. Therefore, it is imperative to conduct research on demonstrations in advance. Henan Province is highly dependent on energy from other provinces, and the power supply and demand situation in Henan Province will become increasingly tense in the future. It is necessary to support Henan Province from the State Grid and coordinate the construction of inter-provincial and inter-regional power transmission channels.

Frequency Control and Optimal Operation of Low-Inertia Power Systems With HVDC and Renewable Energy: A Review

With the integration of large-scale renewable energy sources (RES) and high voltage direct current (HVDC) based inter-regional transmission, modern power systems are facing low-inertia issues and poor frequency regulation capabilities. This paper conducts a comprehensive review on frequency control and optimal operation methods in this context. First, the frequency characteristic of a low-inertia power system is analyzed covering the whole frequency response process. Secondly, the impacts of RES and HVDC integration on system inertia and frequency performance are studied, and the system frequency characteristics considering RES and HVDC are analyzed. Then, the frequency response modes of various frequency regulation resources are compared from the perspective of “source-grid-load-storage”, including their basic control principles and frequency control strategies. Further, from the operation dispatch perspective, the frequency security-constrained power system optimal operation methods are reviewed. Finally, future research trends in this area are discussed.

텍스트마이닝을 통해 본 구비설화의 지역 간 전승 경향의 유사성

This paper analyzed the similarities in the inter-regional transmission trends of oral tales handed down in nine regions using two data collections, 『Comprehensive Korean Oral Literature』 and 『Complementary Edition of Comprehensive Korean Oral Literature』. To this end, we used text mining techniques to go through the analysis process of “data collection → local information pre-processing → regional narrative analysis → visualization”.
 First, 26,542 tale title data were collected from the digital archive of 〈Comprehensive Korean Oral Literature〉, and regional information that was not organized into administrative districts at the “province” level was preprocessed. The data was then divided into nine regions, and these data were again classified based on the year of recording. Next, the corpus morphemes created by collecting only titles from the preprocessed data were analyzed to extract the top 100 frequencies of nouns by region. Then, the extracted noun frequencies were normalized to accurately compare the proportion of oral speech between regions. The distribution of stories between regions was compared by calculating the cosine similarity between regions using the normalization value calculated here. This targeted 384 nouns extracted from 『Comprehensive Korean Oral Literature』 and 435 nouns from 『Complementary Edition of Comprehensive Korean Oral Literature』.
 The results derived through the analysis process were presented through a word cloud for each of the nine regions, the numbers of cosine similarity values ​​between regions, and data visualizing the cosine similarity values ​​on a map. The results indicate that, excluding Jeju, narratives transmitted in the Gyeonggi region show relatively low similarity with those of other regions, making it the most heterogeneous in terms of transmission tendencies across the nation in 『Comprehensive Korean Oral Literature』. On the other hand, in the 『Complementary Edition of Comprehensive Korean Oral Literature』 the regions of Chungcheongbuk-do and Jeollabuk-do exhibit the most heterogeneous transmission tendencies, with Gyeonggi region showing a relatively higher similarity with other regions.

Bridging the Gaps: The Impact of Interregional Transmission on Emissions and Reliability

Bridging the Gaps: The Impact of Interregional Transmission on Emissions and Reliability

An indeterministic fractional two-stage inter-regional energy system optimization model: A case study for the Province of Shanxi, China

The inter-regional power trade inevitably leads to transmissions of carbon and air pollutant emissions (CAEs), which is unfair for energy-dependent regions. Therefore, this study develops an indeterministic fractional two-stage inter-regional energy system (IFTS-IRES) optimization model for planning the energy system in Shanxi Province. The developed model can deal with uncertain parameters expressed as interval values and modify the pre-made policies, which could be an effective method to solve multi-objective optimization problems. Multiple mitigation-policy scenarios are analyzed based on imposing CAEs compensation taxes on electricity consumption regions (ECRs), adjusting renewable energy power targets, and upgrading traditional power plants with carbon capture and storage technology (CCS). The comparison results show that IFTS-IRES is able to detailly reflect the tradeoff between economic development and environmental protection, and the maximal amount of CO2 mitigation will be [1.80, 3.34] K tonne/million RMB. By 2040, wind and biomass would account for [24.55%, 29.02%] and [33.38%, 35.48%] of the power generation capacity, and renewable energy will gradually substitute traditional fossil fuels. Therefore, Shanxi's power system should develop renewable energy rather than upgrade with CCS to realize the goal of carbon peak and carbon neutrality. In addition, the future electricity export will keep increasing, among which the share of wind and biomass power will be [50.86%, 51.69%] and [21.25%, 21.78%]. It is suggested that the mitigation responsibility of inter-regional CAEs should be shouldered by ECRs through paying for compensation taxes. These findings could help decision makers analyze economic and environmental effects with multiple objectives under uncertainties. It provides new insight into regulating the mitigation responsibility existing in inter-regional power transmission grid. The developed model is expected to be applied to other regions heavily dependent on energy resources.

Can inter-provincial transmission reduce regional carbon emissions? Evidence from China

Plagued by worsening pollution in load centers along the eastern coastal regions such as Beijing-Tianjin -Hebei, China is reducing local coal-fired power plants in those regions and relying more on inter-regional power transmission. In recent years, China has accelerated the construction of the West-East Electricity Transmission Project and planned and constructed a number of Ultra-high Voltage (UHV) transmission lines. However, how the impact of inter-regional transmission on carbon emissions needs empirical verification. This paper aims to study the carbon emission reduction effect of inter-regional transmission under nested models of the spatial econometric model for panel data. The empirical results show that although the non-dynamic spatial econometric analysis can find the carbon emission reduction effect of inter-provincial transmission, the long-term effect obtained by the dynamic spatial econometric analysis indicates that the inter-provincial transmission can bring about a slight increase in carbon emissions. The inter-provincial power transmission needs to be supported by sustainable share growth of renewable energy to achieve the targeted mitigation of carbon emissions.

Appropriate transmission grid representation for European resource adequacy assessments

To manage power shortages, system operators must rely on involuntarily demand curtailment to keep the grid operational. Curtailment causes damages to consumers, the cost of which should be balanced against investments in a more reliable power system. To understand the behavior of the system and the expected character of shortages, we rely on resource adequacy studies. These studies provide a probabilistic quantitative framework by emulating system operation over many future years. However, the methods to emulate the power system must balance computational efficiency with accuracy and rely on different simplifications and approximations of the power system and its behavior. Here we show that the transmission model choice particularly impacts the results of these studies, especially for large systems where scarcity risk is shared through markets with significant inter-regional transmission capacities. Our results demonstrate that the most commonly used simple transmission grid models highly distort key adequacy metrics and are likely to cause the misinterpretation of system needs.

Recognizing the nexus between grid infrastructure, renewable energy, net interregional transmission and carbon emissions: Evidence from China

AbstractOver the past few decades, China has undergone an unprecedented structural transformation, stupendously transforming its energy and environmental systems and decarbonizing pathways. Nevertheless, around the share of clean and renewable energy generation with the goal of low‐carbon, it is still ambiguous how the dynamic relationship between the upgrading of grid infrastructure, interregional power trading and the investment and economic foundation that support their collaborative promotion forms. Thus, under the framework of panel vector autoregressive models, we study the bridge that links the key dominant factors in the pattern of electricity supply and demand such as grid infrastructure, power generation share of clean and renewable energy, net power input and carbon emissions. The results show that the governance framework dominated by power grid infrastructure upgrading, interregional power input dependence and carbon constraint mechanism to promote clean‐oriented energy mix is still flawed. In addition to improve the utilization rate of power grid infrastructure, relevant policy makers should devote more efforts to software conditions including interregional and interprovincial power trading and grid‐connecting mechanisms of clean and renewable energy.

Market bidding method for the inter-provincial delivery of cascaded hydroelectric plants in day-ahead markets considering settlement rules

Chinese electricity market reform poses huge challenges to hydropower operations and electricity trading. This study proposes a scheduling method coupling priority electricity and day-ahead trading for large hydropower plants. The study focuses on complex factors such as tariff uncertainty, different types of electricity settlement rules, and inter-provincial electricity transmission links. Spot market tariff scenarios are determined through the Latin hypercube and the K-means methods. A performance formulation of priority electricity deviation considering settlement assessment rules is established. A transmission description for different sub-plants and a triangular linear interpolation method based on binary independent branching mode are proposed to solve inter-regional transmission connections and hydraulic coupling in cascaded hydropower plants, respectively. Finally, the Big M method is employed to equivalently transform the complex non-linear problem into a mixed-integer linear programming (MILP) model. The method is verified with the day-ahead operation of four large hydropower plants downstream of the Jinsha River in China as a case study. Settlement assessment rules, inter-regional power transmission, and price uncertainty are analyzed in three different cases. Three conclusions are obtained: 1) the priority electricity performance rate and the price are positively correlated, which is useful to guide hydropower plants to actively participate in the market. 2) Introducing the prediction error of electricity price in the model can help avoid market decision risk and improve the expected return by approximately 1.2%. 3) Considering the settlement penalty rule is helpful for power generation enterprises to improve power allocation and thus seek higher revenue compared to traditional methods without considering it.

The Spatiotemporal Changes of China's Inter-provincial Power Transmission Network from 2005 to 2020

This study integrates the downscaling model of electricity production consumption, the balance equation of electricity inflow and outflow, and the actual connectivity between provincial power grids into a research framework, and develops a downscaling method for inter-regional power transmission data, thereby obtaining a complete inter provincial power transmission dataset. It was found that from 2005 to 2020, the source of power supply gradually shifted from the Central China Power Grid to the Southwest Power Grid. Sichuan, Yunnan, and some provinces in the southwest region have become important sources of electricity supply. The scale of power transfer from the source point and the scale of power transfer from the sink point are both showing an increasing trend, and the scale of inter provincial and inter regional power transmission is constantly expanding, resulting in a strengthening trend of the close density of network connections.

Study on the efficiency of air pollution control and responsibility allocation in the Yangtze River Delta region in China from the perspective of ecological compensation

Ecological compensation is a critical strategy that can be used to promote regional cooperation for the improvement of air pollution control. Overall, this study considers the relationship between air pollution production and economic growth; through this, we incorporate elements such as ecological compensation, technological progress, and PM2.5, into the framework of sustainable development theory. Under the constraints of the air pollution control objectives, a dynamic computable general equilibrium model was constructed to analyze the efficiency of air pollution control and responsibility allocation in the Yangtze River Delta region. Overall, this study yielded several findings. First, with each 10 billion yuan allocated for ecological compensation in the Yangtze River Delta region, there was an annual average carbon emission reduction of approximately 0.26%; this equated to an annual total carbon emission reduction of approximately 8.3 million tons per 10 billion yuan of ecological compensation. Additionally, the annual average PM2.5 concentration was determined to reduce by 0.72 μg/m3 per 10 billion yuan of ecological compensation; this indicated that effective ecological compensation can lead to a significant improvement in air pollution control. Second, the initial allocation of ecological compensation was distributed in the following order, from the highest to lowest burden: Jiangsu, Zhejiang, Anhui, and Shanghai. Third, we calculated the responsibility for air pollution control; this indicated that local contributions to the inter-regional external transmission of air pollution by the Jiangsu, Zhejiang, Shanghai, and Anhui regions were 65%, 62%, 53%, and 84%, respectively; in contrast, the external contributions to their surrounding regions were 35%, 38%, 47%, and 16%, respectively. Overall, Anhui possessed a higher responsibility for internal responsibility transfers among Jiangsu, Zhejiang, and Shanghai, highlighting the role of Anhui in the fossil fuel industry within the Yangtze River Delta region. Finally, the present study established that there were significant variations in the redistribution of ecological compensation among provinces and cities within the Yangtze River Delta region. Redistribution lead to a reduction in ecological compensation by approximately 1/4 in Zhejiang and Shanghai and approximately 4% in Jiangsu; conversely, this redistribution nearly doubled the ecological compensation allocated to Anhui. Overall, the appropriate allocation of responsibility pertaining to internal trade transfers (i.e., fossil fuels trade) in air pollution and inter-regional external transmission (i.e., air spillover) is crucial for effective air pollution control in the Yangtze River Delta region and other parts of China and, therefore, requires immediate attention.

Estimating the value of energy storage: The role of pumped hydropower in the electricity supply network

This study explores the role of storage systems in reducing the variability of renewable power, focusing on pumped hydropower storage (PHS) systems. We regress the hourly storage by PHS on the hourly solar power generation to estimate the average amount of solar power generation stored by PHS systems. We adopt an instrumental variable approach to mitigate any endogeneity concerns, in which a weighted sunshine duration serves as the instrument for solar power generation. Our estimation results show that PHS systems alleviate the intermittency of solar power generation: an additional 1 MWh of solar power generation corresponds to an additional 0.249 MWh of storage by PHS systems. The relationship between PHS and solar power is more pronounced when the demand is relatively low and solar power generation is large. Inter-regional transmission grids also respond to an increase in solar power generation but to a lesser extent than PHS systems. Based on the estimated coefficients in the empirical analysis, we quantified the value of the existing PHS systems as storage systems that mitigated intermittent solar power generation. The estimated social benefit of avoiding curtailment is 180–280 million yen for a 10 MW scale plant, accounting for 7.7–11.7% of the cost of constructing a new PHS system. The result highlights the importance of effectively utilizing the current PHS capacity.

Persistent transmission of carbapenem-resistant, hypervirulent Klebsiella pneumoniae between a hospital and urban aquatic environments

The increasing prevalence of infections caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae strains (CR-hvKP) prompts the question of whether these strains also circulate outside of clinical settings. However, the environmental occurrence and dissemination of CR-hvKP are poorly studied. In the current study, we investigated the epidemiological characteristics, and dissemination dynamics of carbapenem-resistant K. pneumoniae (CRKP) isolated from a hospital, an urban wastewater treatment plant (WWTP), and adjacent rivers in Eastern China during one year of monitoring. A total of 101 CRKP were isolated, 54 were determined to be CR-hvKP harboring pLVPK-like virulence plasmids, which were isolated from the hospital (29 out of 51), WWTP (23 out of 46), and rivers (2 out of 4), respectively. The period with lowest detection rate of CR-hvKP in the WWTP, August, corresponded with the lowest detection rate at the hospital. Comparing the inlet and outlet of the WWTP, no significant reduction of the detection of CR-hvKP and relative abundance of carbapenem resistance genes was observed. The detection rate of CR-hvKP and the relative abundance of carbapenemase genes were significantly higher in the WWTP in colder months compared to warmer months. Clonal dissemination of CR-hvKP clones of ST11-KL64 between the hospital and the aquatic environment, as well as the horizontal spread of IncFII-IncR and IncC plasmids carrying carbapenemase genes, was observed. Furthermore, phylogenetic analysis showed that the ST11-KL64 CR-hvKP strain has spread nationally by interregional transmission. These results indicated transmission of CR-hvKP clones between hospital and urban aquatic environments, prompting the need for improved wastewater disinfection and epidemiological models to predict the public health hazard from prevalence data of CR-hvKP.

Impacts of RPS and FIT on inter-regional power transmission line layout in China: Considerations of high renewable energy penetration

Given China's severely separated renewable energy (RE) supply area and load area, the power transmission capacity across regions restricts RE penetration and is directly affected by RE-related support policies. Thus, a multi-objective optimization model is developed to explore the impacts of changes in renewable portfolio standard (RPS) and feed-in tariff (FIT) policies on the optimal transmission line layout. The model regards the maximization of RE power grid-on and minimization of the total cost for the optimal line layout, transmission capacity, and technology selection. We found that power transmission in "West-to-East" and "North-to-South" is strengthened, with the capacity expected to expand 2.2 times between 2020 and 2040. 2024–2026 is the period with the most new lines. The new line grows when the RPS target increase. Compared with the business-as-usual scenario, in the two scenarios where RPS increased by 10% and 15%, the newly built lines' number could grow by 35% and 21%, respectively. On the contrary, if the FIT subsidy continues beyond 2020, the demand for new line construction may decrease, reducing 480 TWh (FIT2025) and 330 TWh (FIT2040) of RE power on-grid. Further, the penetration proportion of renewable generation could be 55.8%–61.8% in 2040, achieving high penetration of RE in China.

Power coming from the sky: Economic benefits of inter-regional power transmission in China

Broader trading opportunities usually lead to higher economic benefits, and this is also true for cross-regional electricity transmission. However, few studies have rigorously confirmed the economic benefits of cross-regional power transmission for both power-input-region and power-output-region. In this paper, we take the spatial effects as a perspective to demonstrate the economic benefits of inter-regional power transmission (IRPT) at both theoretical and empirical levels. Especially, after the first phase of the West to East electricity transmission project in China, IRPT across regions plays a more critical role in achieving balanced regional development and cross-regional common prosperity. This paper first estimates the economic impacts of electricity transfer to the power-importing and exporting provinces through the fixed-effect and instrumental variable methods. Further, the study relaxes the original assumptions and innovatively constructs spatial weight matrices of electricity transmission, and estimates the spatial direct, indirect, and total effects of cross-regional electricity transfers. Arguing the economic benefits to both local and other regions brought about by power import and export in the IRPT, this paper refutes the view of trade protectionism and reaffirms that IRPT is conducive to widespread economic prosperity.

Interbank Networks and the Interregional Transmission of Financial Crises: Evidence from the Panic of 1907

Interbank Networks and the Interregional Transmission of Financial Crises: Evidence from the Panic of 1907