Large-scale Farms Research Articles

Economic and environmental analyses of the construction of on-site, large-scale photovoltaic farms

This paper addresses the construction of large-scale photovoltaic farms. The paper describes the issues of the current overconsumption of energy from traditional sources and the associated overuse of fossil fuels. Alternatives to these processes are presented based on literature sources, and the use of renewable energy sources, focusing on solar energy, is recommended here. In the research section, attention was focused on the economic and environmental aspects of ventures involving the construction of large-scale farms by manufacturing companies with high monthly energy consumption. In the first stage of the work, economic analyses were carried out based on data obtained from photovoltaic installation companies. For the simulation, an assessment of the costs and benefits of building a photovoltaic farm for a steel construction company located in eastern Poland was used. Another element of the research part of the study was an analysis of the results of a questionnaire survey, which was conducted among people living in the vicinity of such farms. On this basis, the environmental impact of neighbouring areas of this type of investment was estimated. Positive conclusions from the analyses made it possible to recommend the construction of this type of facility, especially for manufacturing plants with high electricity consumption.

Life cycle environmental analysis of offshore wind power: A case study of the large-scale offshore wind farm in China

China's decarbonization is indispensable for the large-scale utilization of renewable energy. In this process, the development of offshore wind energy has become an important support, because in the eastern region of China, especially the coastal areas, there's the most load requirements but limited onshore renewable resources. Under the goals of both carbon neutral and sustainable development, however, there's still a research gap in evaluating the environmental impacts of large-scale offshore wind plants in China. In this study, the research performed a comprehensive process-based life cycle environmental analysis of a large-scale (400 MW) offshore wind farm with large wind turbine units (5 MW) in China. Global Warming Potential is 25.73 g CO2-eq/kWh and greenhouse gas payback time is calculated as 12.05 months. Fossil fuel consumption amounts to 0.31 MJ/kWh with an energy payback period of 25.56 months. Material resources and ecotoxicity to freshwater need more attention with the values of 1.68 CTUe/kWh and 3.32 10−6 kg Sb-eq/kWh, respectively. The manufacturing stage contributes most to all the impacts examined. The disposal and recycling process shows significant environmental benefits for most impacts but exerts burdens on the particulate matter. Focusing on Global Warming Potential, the wind turbine generation set has the highest effect, among which the blades contribute 73.2% of it. Further, the evolution of electricity and heating mix of China and use of biomass-based precursors could decrease 57% of the blades' greenhouse gas emissions in 2050. This study could provide guidance on the sustainable design and policy-making of offshore wind farms.

The impact of smart input subsidy program on farm productivity: Evidence from Tanzania

Policymakers have a renewed interest in input subsidy programs in sub-Saharan Africa. However, the evidence of the program's impact is mixed. This paper uses the case of Tanzania's National Agricultural Input Voucher Scheme (NAIVS) to examine its effect on farm productivity. To account for the endogeneity problem arising from the non-random targeting of beneficiaries, this study employed a staggered difference-in-differences approach with a double robust estimator method on a three-wave panel survey. This approach is relevant because the treatment variable—NAIVS participation was gradually rolled out to households over multiple periods and groups. The results do not show evidence that the NAIVS program increased farm productivity. However, the group aggregate effects suggest that the group initially treated in 2010 experienced a positive and significant impact on maize production and income. This could indicate that during the early stages of the NAIVS program, extra effort was likely invested to ensure its effectiveness. Furthermore, the heterogeneous effect of farm size reveals that the NAIVS program increased the participation of beneficiary households with large-scale farms rather than small-scale farms. This suggests that the program did not effectively target resource-poor households. Finally, this paper calls for effective targeting and careful implementation of programs to improve farmer productivity.

Development strategy of non-GMO organism for increased hemoproteins in Corynebacterium glutamicum: a growth-acceleration-targeted evolution

Heme, found in hemoproteins, is a valuable source of iron, an essential mineral. The need for an alternative hemoprotein source has emerged due to the inherent risks of large-scale livestock farming and animal proteins. Corynebacterium glutamicum, regarded for Qualified Presumption of Safety or Generally Recognized as Safe, can biosynthesize hemoproteins. C. glutamicum single-cell protein (SCP) can be a valuable alternative hemoprotein for supplying heme iron without adversely affecting blood fat levels. We constructed the chemostat culture system to increase hemoprotein content in C. glutamicum SCP. Through adaptive evolution, hemoprotein levels could be naturally increased to address oxidative stress resulting from enhanced growth rate. In addition, we used several specific plasmids containing growth-accelerating genes and the hemA promoter to expedite the evolutionary process. Following chemostat culture for 15 days, the plasmid in selected descendants was cured. The evolved strains showed improved specific growth rates from 0.59 h−1 to 0.62 h−1, 20% enhanced resistance to oxidative stress, and increased heme concentration from 12.95 µg/g-DCW to 14.22–15.24 µg/g-DCW. Notably, the putative peptidyl-tRNA hydrolase-based evolved strain manifested the most significant increase (30%) of hemoproteins. This is the first report presenting the potential of a growth-acceleration-targeted evolution (GATE) strategy for developing non-GMO industrial strains with increased bio-product productivity.

Modelling of bifacial photovoltaic farms to evaluate the profitability of East/West vertical configuration

East/West (E/W) vertical bifacial photovoltaic (PV) modules can achieve higher profits than the conventional North/South (N/S) tilted configuration depending on the design choices and external conditions. In this study a model based on 2D view factor concept is developed to estimate the power generated by a large-scale bifacial PV farm, considering the non-uniformity of the incident irradiance and the spectral impact. A validation using measured data is performed, focusing on the non-uniformity of the rear irradiance. This model is used to compare the profitability between E/W vertical and N/S tilted PV farm configurations, considering higher prices during noon with respect to morning/evening periods. The results identify the ratio between these two price values as the key variable that influences the comparison between the PV farm configurations. Specifically, a sufficiently high price ratio ensures the higher profitability of E/W vertical modules, however, the exact value is dependent on the location and the design variables. In general, higher row-to-row distance and lower diffuse fraction enhance the profitability of the E/W vertical over the N/S tilted configuration. On the other hand, elevation of the modules, curtailment strategies and hybrid solutions have a minor influence.

Online dynamic ATC computation with large-scale wind farms

Online dynamic ATC computation with large-scale wind farms

Vietnamese cassava varieties progression across 50 years

Vietnamese cassava varieties constitute the fundamental and pivotal element in the sustainable development programme for cassava. This article aims to encapsulate the advancements made over nearly five decades in breeding and enhancing Vietnamese cassava varieties. It delineates the suitable cassava variety structures for each period and ecological region. The selection of cassava varieties exhibiting high starch yield and disease resistance, coupled with the establishment of a suitable and efficient cassava cultivation model, exemplified by 10T for Vietnamese cassava varieties KM568, KM539, KM537, KM569, and KM94, stands as a cornerstone for sustaining cassava development over the years. Presently, we advocate for farmers to cultivate promising cassava varieties such as KM568 or KM539 (an enhanced version of the International Center for Tropical Agriculture (CIAT) cassava variety C39, refined through multiple breeding cycles from 2004 onwards), KM537, KM569, or HN1 (originally known as TMEB419), alongside popular cassava varieties: KM440, KM419, KM94, KM7, STB1, KM414, KM98-7, KM140, KM98-5, KM98-1. We have conducted Distinctness, Uniformity, and Stability (DUS) and Value for Cultivation and Use (VCU) tests, showcasing outstanding cassava varieties in large-scale farming, thereby providing compelling evidence for the prudent conservation and sustainable development of cassava. Vietnamese cassava progression (1975 to date) has traversed six stages, with five waves of restructuring cassava varieties, aligning with target orientations, farming conditions, and market demands, culminating in 16 popular cassava varieties and four promising cassava varieties KM568, KM539, KM537, and KM569.

A retrospective study of thermal events on the mortality rate of hutch-reared dairy calves.

Heat stress in hutch-reared dairy calves (Bos taurus) is highly relevant due to its adverse effects on animal welfare, health, growth, and economic outcomes. This study aimed to provide arguments for protecting calves against heat stress. It was hypothesized that the thermal stress caused by high ambient temperature in summer months negatively affects the survival rate in preweaning calves. In a retrospective study, we investigated how calf mortality varied by calendar month and between thermoneutral and heat stress periods on a large-scale Hungarian dairy farm (data of 46,899 calves between 1991 and 2015). The daily mortality rate was higher in the summer (8.7-11.9 deaths per 10,000 calf days) and winter months (10.7-12.5 deaths per 10,000 calf-days) than in the spring (6.8-9.2 deaths per 10,000 calf-days) and autumn months (7.1-9.5 deaths per 10,000 calf-days). The distribution of calf deaths per calendar month differed between the 0-14-day and 15-60-day age groups. The mortality risk ratio was highest in July (6.92). The mortality risk in the 0-14-day age group was twice as high in periods with a daily mean temperature above 22°C than in periods with a daily mean of 5-18°C. Heat stress abatement is advised in outdoor calf rearing when the mean daily temperature reaches 22°C, which, due to global warming, will be a common characteristic of summer weather in a continental region.

Serological investigation and isolation of Salmonella abortus equi in horses in Xinjiang

BackgroundSalmonella enterica subspecies enterica serovar abortus equi (S. abortus equi) is one of the main pathogens that causes abortion in pregnant horses and donkeys, which was highly infectious and greatly restricts the healthy development of the horse industry.ObjectivesIn order to investigate the prevalence and biological characteristics of S. abortus equi in different regions and breeds of horses in Xinjiang.MethodsThis study conducted ELISA detection of S. abortus equi antibodies on serum samples of 971 horses collected from three large-scale horse farms and five free-range horse farms in Yili Prefecture and Bayingol Mongolian Autonomous Prefecture of Xinjiang from 2020 to 2023. On this basis, bacterial isolation, culture, identification, and drug sensitivity tests were conducted on 42 samples of aborted foal tissues and 23 mare vaginal swabs.ResultsThe results showed that the positive rate of S. abortus equi antibody was as high as 20.91% in 971 horse serum samples. Among them, the positive rate in the Ili region (29.09%) was significantly higher than that in the Bayingole region (11.24%), and the positive rate in mares (22.45%) was higher than that in stallions (14.05%). In terms of horse breeds, the positive rates of self-propagating thoroughbred horses, half-bred horses, Ili horses and Yanqi horses were 43.22%, 28.81%, 14.72% and 11.24% respectively. In addition, S. abortus equi was more susceptible to juvenile and elderly horses, with positive rates of 70.00%and 41.86%, respectively, both of which were significantly higher than young (10.97%) and adult (19.79%) horses. Further, 9 strains of S. abortus equi were obtained through bacterial isolation, culture and identification, which were resistant to five antibiotics (Clarithromycin, Clindamycin, penicillin, Sulfamethoxazole and Rifampicin), and sensitive to 13 antimicrobial agents (Amoxicillin, Ciprofloxacin and Gentamicin, et al.).ConclusionThere was a high infection rate of S. abortus equi in Ili Prefecture and self-propagating thoroughbred horses, and juvenile or old mares were more susceptible, which will provide scientific basis for the prevention of S. abortus equi infection in different regions and breeds of horses in Xinjiang.

Assessing the inhibitory effect and intervention mechanism of food traceability system on reducing hog farmers’ overuse of animal antibiotics in China

The use of animal antibiotics is a double-edged sword. It can be used for disease treatment, health protection, and growth promoters. It also creates antibiotic residues and resistance, poses risks, and damages food safety, ecosystems, and public health. Under the pressure of disease risk and expected losses, farmers' overuse of animal antibiotics exacerbates this dual objective incompatibility. In this study, we employ the endogenous switching regression (ESR) model and the mediating effect method to empirically analyze the inhibitory effect and intervention mechanism of the food traceability system (FTS) on reducing farmers’ overuse of antibiotics by using the survey data of hog farmers from China. This paper measures the “dose” unit of antibiotics farmers use regarding cost and the active ingredients of antibiotics per kilogram of treated infected hogs. The study finds evidence that the FTS exerts a significant inhibitory effect on the overuse of antibiotics by farmers. The counterfactual hypothesis unveils that non-participation in the FTS by the involved farmers will increase the cost of antibiotics overuse by 0.080 yuan/kg, while if the farmers currently not participating are to engage with the FTS, the price will decrease by 0.126 yuan/kg. This effect persists across control variables controlled in turn and the unit doses of active ingredients of tetracycline, sulfonamides, β-lactam, chloramphenicol, and macrolide antibiotics. Moreover, our results reveal thatthe inhibitory effects of the FTS on over-the-counter and broad-spectrum antibiotics are more significant than on prescription and narrow-spectrum antibiotics. The results show that the inhibition effect of the FTS on the overuse of antibiotics by free-range, professional, and large-scale farmers exhibits an approximately inverse-U curvilinear relationship. Besides, the intervention mechanism of the FTS on the overuse of antibiotics by farmers mainly consists of social reputation maintenance, liability traceability for antibiotic residues, and biosafety enhancement, and the proportion of their mediating effects in the total impact are 24.22%, 21.84%, and 10.87%, respectively. Our empirical study has yielded several implications, such as strengthening the FTS construction, improving farmers’ antibiotic use skills, promoting standardized breeding levels, and increasing the market premium for food products that adhere to antibiotic residue standards. These outcomes not only contribute to the improvement of livestock production safety but also reduce the problem of antibiotic overuse.

Risk level assessment of typhoon-induced wave fields around a large-scale suspended mussel farm

Suspended shellfish aquaculture, utilizing longlines and buoys fixed on the sea surface, is a crucial source of global seafood. However, typhoons, as the most common disasters in coastal regions, can generate massive waves and pose a threat to the safety of suspended aquaculture facilities. Therefore, it is essential to investigate the risk levels associated with suspended aquaculture farms during typhoon waves. The example of a large-scale suspended mussel farm in the East China sea was examined in this study. The wave conditions under extreme wind conditions (25m/s) and different typhoon paths were predicted using the SWAN model and modeled results compared well with the observed wave and wind data. The results indicated that when the center of the east-side typhoon was located at the same latitude as the farm, it will face the highest risk level. However, for the west-side and intermediate sweeping typhoons, the risk level reached highest in the farm, when the typhoon center is lower than the latitude of it. Under the combined effects of wind fetch and topography, the risk level in the southeast farming area of the island is the highest under different wind conditions. The farms to the northwest of the island face a higher risk level during the passage of east-side sweeping typhoons, while the southern farms of the island experience an elevated risk level during the west-side and intermediate sweeping typhoons. It is suggested that farming regions with lower risk levels are more conducive to the cultivation of species with longer culture cycles. Conversely, regions considered at higher risk are more suitable for species with shorter culture cycles. The study affords a reference for the optimization and insurance of suspended aquaculture farms.

Agricultural subsidies in a political economy: Can collective action make smallholder agriculture contribute to development?

Malawi’s economy is heavily dependent on agriculture, of which a majority are smallholder farmers. With smallholder farmers constituting more than 80% of the population, the government’s policies have mainly focused on achieving redistribution goals of the society, minding less about the inefficiencies in smallholder farming. The current study assessed and compared the efficiency levels of large scale and small-scale farmers amidst huge government expenditures in agricultural subsidies on smallholder farmers. Through a SWOT analysis and literature review approach that dwelt much on the qualitative case study approach, the study found that it is only through attaining economies of scale that small farms can attain the efficiency levels of large-scale farms. Following this finding that large farmers are more efficient; the study proposes models that would mimic the behaviour of large farmers. In this study, we evaluated the strengths, weaknesses, opportunities and threats of various models proposed to improve efficiency of small farms. Three models were evaluated namely, contract farming, cooperative development and land consolidation models. These models were selected for review because the theory of collective action ensures that they mimic the farm behaviour of a large farmer. The paper recommends a hybrid of land consolidation model with selected elements of contract and cooperative development models.

The Government–Farmer Cooperation Mechanism and Its Implementation Path to Realize the Goals of Optimizing Grain Planting Structure

In order to alleviate the grain supply–demand structural contradictions and ensure the realization of grain planting structure optimization goals, it is necessary to clarify the interactive relationship between multiple entities, establish a cooperation mechanism, and explore its implementation paths. To this end, a differential game model is built to compare and analyze the optimal strategies, optimal benefits, and overall system outcomes for both the government and farmers under three scenarios: the Nash non-cooperative game, the Stackelberg game, and the collaborative cooperation game. Then, key factors and their influencing mechanisms that affect the government–farmer cooperation mechanism are revealed. Finally, the csQCA model is used to explore the implementation paths for different stakeholders to ensure the sound operation of the cooperation mechanism. The results show the following: (1) The government–farmer cooperation mechanism should consist of an inner core system with the government–farmer interaction as the core and an outer system comprising the market environment, cooperation environment, and institutional environment. These two systems should coordinate with each other, respond to each other, and drive progress together. (2) The cooperation mechanism can optimize behavioral enthusiasm, resulting in individual and overall benefits for both the government and farmers. However, its scientific and orderly implementation is affected by factors such as the cost coefficient. Additionally, subsidies serve as a powerful policy tool to enhance farmers’ enthusiasm, thereby increasing the benefits for both parties and maximizing the effectiveness of the cooperation mechanism. (3) There are three implementation paths corresponding to large-scale farmers, rural elites, and small-scale farmers: being led by external policy tools, linkage guidance between decision-making environment and willing subjects, and factor allocation and environmentally driven decision-making. These findings can provide theoretical support and case reference for marginal farmland management and planting structure optimization management in underdeveloped areas.

Impacts of large-scale suspended mussel farm on seston depletion

The productivity of a suspended mussel farm depends on the abundance of naturally available food. This study constructs a tracer decay model that incorporates mussel filtration and integrates it with a well-established 3D ocean circulation model to examine the spatiotemporal variation of seston depletion at a large-scale suspended mussel farm on Gouqi Island, located offshore in the East China Sea. A novel Wirewalker ocean-wave-powered vertical profiling system was deployed to monitor chlorophyll-a concentration at the edge of the mussel farm. The observed profiles of chlorophyll-a concentration revealed that the current exiting the farm during ebb tide is associated with a lower concentration compared to the current entering the farm during flood tide. This suggests that the filter feeding activity of mussels within the farm is primary contributor to this reduced chlorophyll-a concentration. This finding is consistent with the tracer model results, which indicates a higher tracer concentration entering the farm and a lower tracer concentration exiting it. The model results suggest that the blocking effect of the farm can significantly exacerbate seston depletion, particularly during neap tide as opposed to spring tide. The interplay of tidal characteristics and topography has resulted in two areas that are particularly vulnerable to seston depletion: one centrally situated within the mussel farm, and another near the islands. However, it is possible to alleviate seston depletion by aligning the waterway within the farm with the major axis of the tidal ellipse. Consequently, it is crucial to consider tidal conditions surrounding the farm for optimal farm layout design, increased production, and enhanced stock quality in shellfish farms facing seston depletion.

Meat and morality: The moral foundation of purity, but not harm, predicts attitudes toward cultured meat

Cultured meat (also referred to as cultivated, cell-based, or cell-cultured meat) is a novel food technology that is presented as a method of meat production without reliance on large-scale industrial farming. The pro-cultured meat narrative rests, in part, on a moral foundation: cultured meat is purported to alleviate the environmental and animal welfare harms associated with farmed meat. Despite this narrative, no research has examined which moral values underpin attitudes towards cultured meat. To examine this, we surveyed 1861 participants from the United States and Germany about their moral foundations and their attitudes towards cultured meat. In line with predictions, people who more strongly endorse moral values about purity (i.e., had higher scores on the purity subscale of the moral foundations scale) held more negative attitudes towards cultured meat. However, this relationship was much more consistent among participants from the United States than participants from Germany. Against predictions, attitudes towards cultured meat were not reliably associated with the extent to which people focus on harm as a moral foundation. The latter finding was particularly surprising in light of harm-reduction narratives around cultured meat. These findings demonstrate the need for a more nuanced discussion about, and understanding of, consumer concerns around cultured meat and the values that underpin them.

Case reports involving coinfection with Avibacterium paragallinarum and Ornithobacterium rhinotracheale in broiler chickens and Avibacterium endocarditis in broiler breeding hens in Poland

ABSTRACT The study describes three clinical cases of infection with Avibacterium spp.. In case no. 1, respiratory clinical signs and high mortality (0.7–4.2% daily; total 21.2%) in Ross 308 broiler chickens were shown to be caused by coinfection with sequence type 9 of O. rhinotracheale presumptive serotype A and A. paragallinarum presumptive serotype B. The identical (pulsed-field gel electrophoresis) restriction pattern (pulsotype) of seven A. paragallinarum isolates indicated that infectious coryza in broilers was caused by the same clone. In cases 2 and 3, sudden increased deaths in Ross 308 broiler breeders (especially males) with lesions in the endocardium (valvular or mural endocarditis) were shown to be caused by A. endocarditis. Among nine antibiotics tested, florfenicol was the only antibiotic to which all A. paragallinarum and O. rhinotracheale isolates were susceptible. Out of the eight antibiotics tested, 11 A. endocarditis isolates from both clinical cases of infective endocarditis were susceptible to penicillin, amoxicillin, doxycycline and florfenicol. The A. endocarditis isolates tested in both clinical cases had different PFGE patterns (pulsotypes), but identical within a case. The causes of infectious coryza and infective endocarditis in the cases presented have not been determined. In the prevention of infectious diseases in large-scale livestock farming, it is very important to follow the rules of biosecurity.

Research Progress in Facility Agriculture and Lighting by Bibliometric Analysis Based on CiteSpace

Given the pressures of internation-al market competition, the dual constraints of domestic resources and the environment, and the uncertainties posed by climate change, bolstering agricultural infra-structure construction is a realistic demand and a crucial approach for implementing emerging grain security strat-egies, particularly in developing countries. Facility agriculture is characterized as a modern agricultural production mode that improves or creates favorable environmental conditions within a specific locality. With the rapid expansion of large-scale facility agriculture, there has been an increased demand for various types of energy, including electricity, gas, cold, and heat. Agricultural lighting equipment used in facility agriculture is a modern agricultural technique that applies engineering technology to regulate light supplementation in the production process. Facility lighting offers several advantages over traditional methods, such as higher photovoltaic conversion efficiency, adjustable spectrum, high photosynthetic efficiency, energy efficiency, environmental friendliness, long lifespan, monochromatic light, cold light source, and compact size. Promoting national food security, carbon neutrality, returning farmland to forests, and implementing low-carbon green agricultural policies all contribute to the favorable use of facility agriculture lighting. This study aims to provide a systematic summary of the relevant research conducted in the past decade using Citespace software. The advantage of facility agriculture for carbon sequestration capacity can effectively reduce net carbon emissions from facility agricultural production activities. In addition, the combination of agriculture and the Internet of Things can effectively improve agricultural production efficiency and economic returns. Combining artificial intelligence and other technologies with facility agriculture engineering, based on multi-source data fusion, intelligent early warning for facility agriculture energy internet can be used to prevent agricultural meteorological disasters. More importantly, it helps maintain global food security, eliminate hunger, and reduce economic inequality. The findings of this study will contribute to a deeper understanding of agricultural lighting equipment, serving as a new theoretical foundation for achieving agricultural emission reduction targets and promoting agricultural technical cooperation.

The Impact of Crop Insurance on Fertilizer Use: Evidence from Grain Producers in China

This study aims to examine the influence of crop insurance on the utilization of chemical fertilizers using plot-level data. The dataset utilized in this analysis consists of information obtained from 1039 participants residing in four major grain-producing provinces (Heilongjiang, Zhejiang, Henan, and Sichuan) in China. To address the potential issue of endogeneity, instrumental variables were employed to establish a causal relationship within the empirical model. The findings of this study indicate that crop insurance does not exert a statistically significant impact on overall fertilizer input in China. Nonetheless, the effect varies across different categories of farmers. Specifically, large-scale farmers experience a moderate reduction in fertilizer input as a result of crop insurance, while small-scale farmers do not demonstrate a significant effect. It is essential to strike a balance between risk protection and the potential influence of moral hazard in order to enhance future crop insurance policies.

Recovering farming supply chains from animal epidemics via government subsidies

In recent years, animal epidemics – such as African swine fever and bird flu – break out more frequently in both developed and developing economies, causing serious economic losses and animal product shortages. To restore animal product supply, many governments offer two agricultural subsidies to farms: (i) the culling compensating subsidy (CCS), which guarantees a floor price for culled animals, and (ii) the scaled construction subsidy (SCS), which supports large-scale farms to enhance their production capacities. We develop a three-stage Stackelberg game framework to capture the strategic interactions among the government, large- and small-scale farms. In particular, the two types of farms differ in their epidemic prevention and control capabilities and must operate under yield uncertainty. We study two cases regarding whether the government requires a minimum BS for the SCS. In each case, we analyze the equilibrium decisions of the profit-seeking farms and characterize the structure of the government’s optimal subsidy programs with an earmarked budget to maximize social welfare. Moreover, we identify the conditions under which the government should adopt the “SCS only strategy”, “CCS only strategy”, or offer the two subsidies simultaneously. Furthermore, we examine the effectiveness of the subsidy programs in terms of consumer surplus, farms payoffs, and social welfare. We show that in both cases, these programs can make the three stakeholders achieve a win–win–win situation by prioritizing a reasonable CCS according to the subsidy budget. We leverage our analyses to offer insights that can help generate policy recommendations for stakeholders in countries suffering from animal epidemics.

Sub-Synchronous Oscillation Constrained Communication-Free Grid Frequency Control of Offshore Wind Farm Linked HVDC System

This paper proposes a frequency control method of a voltage source converter (VSC) high-voltage direct current (HVDC) system for large-scale offshore wind farms (OWFs) integration into an AC grid. Without frequency control, power output of OWFs varies with the wind velocity and it causes a grid frequency fluctuation. This fluctuation on the AC grid is becoming more severe as the level of wind power penetration increases. The previously suggested communication-free controls are vulnerable to continuously changing frequency fluctuations owing to concerns about its excessive energy releases. Therefore, our proposed control enables OWFs with HVDC to participate in grid frequency regulation continuously by considering its energy state when AC grid frequency fluctuates. In addition, there is a concern about sub-synchronous oscillation (SSO) instability owing to its cascading frequency control structure. A simplified small-signal model is developed to reveal out the existence of these SSO problems and its main factors in the frequency control scheme. Using developed model, overall system stability is comprehensively investigated. Also, a damping controller to mitigate SSO instability is also suggested and validated through simulation. To demonstrate the effectiveness of overall proposed frequency control, time-domain simulations were also carried out utilizing PSCAD/EMTDC under varying wind velocity condition.