Potential for grid efficiency based on a combination of leakage reactances of transformers of a transmission interconnecting line: Application of an exhaustive search algorithm

Transmission interconnecting lines (called interconnectors in this study) are built to facilitate the exchange of active and reactive power between two areas of a network. Step-up and step-down transformers are required at the ends of the interconnector when interconnectors are at a different voltage, usually higher, than the networks to be connected. A study was carried out to examine the impact on active power losses of a combination of leakage reactances of the transformers at the ends of an interconnector. The study assessed whether combinations can lead to different levels of active power losses and can thus affect the efficiency of the system. It was found that the combinations of reactance have a tangible impact on the power that flows through the interconnector and, consequently, on the sharing of apparent power between the interconnector and the rest of the network. The total active power losses varied appreciably with the various combinations of reactances, resulting in the life-cycle cost of active power losses also varying with the combinations. The study showed that the combination needs to be carefully made, considering that such a choice can have a significant impact on techno-economic aspects of the power system

Evaluation of the impact of distributed synchronous generation on the stochastic estimation of financial costs of voltage sags

Abstract: Power system faults can cause voltage sags that, if they are less than voltage sensitivity threshold of equipment, can lead to interruption of supply and lead to incurring of financial losses. The impact of distributed generation (DG) on these financial losses is investigated in this work. Using the method of fault positions, a stochastic approach to determine voltage sag performance, profiles of magnitudes of remaining voltages at a monitoring point for faults occurring along lines in the network is developed. It follows that an expected number of critical voltage sags at a monitoring point is calculated and the expected cost of these sags is derived for various voltage sensitivity threshold limits. An illustrative study is carried out comparing the expected costs of voltage sags for a network without DG with a DG case, for various mixes of customers. It is shown that in the presence of DG, the expected costs of voltage sags are lesser for all voltage sensitivity criteria assumed and for all customer mixes. The study demonstrates that the impact of incorporating DG sources results in a reduction in the expected cost of voltage sags

The effect of a warm electron beam on slow electron-acoustic solitons

The effects of the inclusion of finite drift speed of a warm electron component on the existence of arbitrary amplitude slow electron-acoustic solitons are investigated in a model with ions and cool, warm, and hot electrons. All plasma species are treated as adiabatic fluids. For fixed densities of the cool, warm, and hot electrons, the admissible Mach number ranges of the supported negative potential solitons are found to widen with increasing warm electron beam speed, up to a maximum value of vdbwo = 0.7. Beyond this maximum value, the soliton Mach number ranges become narrower and vanish completely at vdbwo = 1.084 where a switch to positive polarity solitons occurs. For a fixed value of the drift speed of the warm electrons, the cool electron density value at which the switch to positive polarity soliton occurs is the lowest when there is no streaming of the warm electrons but increases with increasing drift speed

Climate Change and Small Farmers’ Vulnerability to Food Insecurity in Cameroon

There is interconnectedness between small farmers’ productivity, climate change, and the state of food security in Africa south of the Sahara. The neglect of small farmers amidst climate change challenges in the Global South suggests the existence of a vicious circle of low productivity and deprivation that exacerbates the vulnerability of small-scale farmers, who largely depend on rain-fed agriculture to feed their families and nations. The limited adaptive capacity of these farmers in the face of growing instability in rainfall and temperatures is affecting the output, profitability, and survival of these small-scale farmers, whose production is principally for the local market and therefore critical for community food security. The underdeveloped local agricultural sector and limited investment in climate-smart agriculture also affect small farmers’ productivity and ability to meet the food demands of increasing populations. This paper examines the challenges of small-scale farmers in a resource-rich economy, their vulnerability to climate change, and the effects on food insecurity. It is based on an in-depth qualitative case study of 30 residents from the Tiko and Santa areas in the South West and North West regions of Cameroon, respectively. The paper argues that small farmers’ vulnerability to climate-induced agricultural losses increases the risks of food insecurity for the growing Cameroonian population

Factors associated with farmers’ use of fee-for-service advisors in a privatized agricultural extension system

The privatization of agricultural advisory and extension services in many countries and the associated pluralism of service providers has renewed interest in farmers’ use of fee-for-service advisors. Understanding farmers’ use of advisory services is important, given the role such services are expected to play in helping farmers address critical environmental and sustainability challenges. This paper aims to identify factors associated with farmers’ use of fee-for service advisors and bring fresh conceptualization to this topic. Drawing on concepts from service ecosystems in agricultural innovation and using the theory of planned behavior to define a plausible directed acyclic graph, we conducted a cross-sectional study of 1003 Australian farmers and their use of fee-for service advisors, analyzing data using generalized ordinal logistic regression models. We defined three categories: farmers who used fee-for-service advisors as their main source of advice (‘main source'), farmers who used them but did not consider them their main source of advice (‘non-main source’), and farmers who did not use them (‘non-user’). The factors most strongly associated with use of fee-for-service advisors (both as 'main source' and 'non-main source') were: the farm being in a growth/expanding business stage; behavioral beliefs that paying for advice provides control and helps identify new opportunities in farming; endorsement of paying for advice from others in the farm business and farmer peers; attitudes relating to the benefit and value for money from advice; and perceived behavioral control related to confidence in accessing advice. These findings can inform strategies to enable use of fee-for-service advisors. For example, they highlight the need to increase the social acceptance of paying for advice and to assist advisors to better articulate the value of their services in terms that farmers view as important. Currently, mechanisms for professionalizing and certifying advisory services are a focus for policy makers in enabling farmers’ use of advisors. Our findings indicate that these mechanisms on their own would not necessarily lead to greater use of fee-for-service advice, because use is also based on several social and attitudinal factors in addition to perception of quality. Greater emphasis on the social and attitudinal factors found in this study is required when developing strategies to enable the use of fee-for-service advisors

Factors associated with farmers’ use of fee-for-service advisors in a privatized agricultural extension system

The privatization of agricultural advisory and extension services in many countries and the associated pluralism of service providers has renewed interest in farmers’ use of fee-for-service advisors. Understanding farmers’ use of advisory services is important, given the role such services are expected to play in helping farmers address critical environmental and sustainability challenges. This paper aims to identify factors associated with farmers’ use of fee-for service advisors and bring fresh conceptualization to this topic. Drawing on concepts from service ecosystems in agricultural innovation and using the theory of planned behavior to define a plausible directed acyclic graph, we conducted a cross-sectional study of 1003 Australian farmers and their use of fee-for service advisors, analyzing data using generalized ordinal logistic regression models. We defined three categories: farmers who used fee-for-service advisors as their main source of advice (‘main source'), farmers who used them but did not consider them their main source of advice (‘non-main source’), and farmers who did not use them (‘non-user’). The factors most strongly associated with use of fee-for-service advisors (both as 'main source' and 'non-main source') were: the farm being in a growth/expanding business stage; behavioral beliefs that paying for advice provides control and helps identify new opportunities in farming; endorsement of paying for advice from others in the farm business and farmer peers; attitudes relating to the benefit and value for money from advice; and perceived behavioral control related to confidence in accessing advice. These findings can inform strategies to enable use of fee-for-service advisors. For example, they highlight the need to increase the social acceptance of paying for advice and to assist advisors to better articulate the value of their services in terms that farmers view as important. Currently, mechanisms for professionalizing and certifying advisory services are a focus for policy makers in enabling farmers’ use of advisors. Our findings indicate that these mechanisms on their own would not necessarily lead to greater use of fee-for-service advice, because use is also based on several social and attitudinal factors in addition to perception of quality. Greater emphasis on the social and attitudinal factors found in this study is required when developing strategies to enable the use of fee-for-service advisors