Mathematical modeling of the reliability of a hybrid micro-power plant

In the conditions of regions with relatively low solar and wind potentials, interruptions in power supply to consumers powered by micro-power plants based on renewable energy sources may be due to a decrease in the power of wind power plants, photovoltaic modules with insufficient wind speed and insolation, respectively, to provide power to consumers. A study of the reliability of a system including a wind power plant, photovoltaic modules, a hybrid charge controller, an energy storage device and an inverter was carried out using a logical-probabilistic method. As part of the study, an analysis was made of the structure of the power supply system and its modes of operation in the event of various events: failure of system elements, replacement of failed elements, diagnostics of elements, decrease in the power of the wind power plant and photovoltaic modules. Combinations of events leading to a power failure of consumers connected to a hybrid micro-power plant have been determined. A fault tree was built for the hybrid micro-power plant. Expressions are obtained for calculating the probability of short-term, long-term power supply interruptions, the probability of power supply interruptions occurring when off-design insolation and wind speed occur. Mathematical modeling of the reliability of the hybrid micro-power plant for the conditions of the central part of the Republic of Mari El has been carried out. It has been determined that the probability of a system failure is determined mainly by the probability of long power outages. In this case, the reliability indicators of the system as a whole are largely determined by the values of the reliability indicators of the hybrid controller and inverter. Keywords: YBRID MICRO-POWER PLANT, RENEWABLE ENERGY SOURCES, RELIABILITY, RURAL POWER SUPPLY

Supply chain of some medicines in health facilities in Jos, Nigeria: post Federal Ministry of Health mapping survey

The Nigerian health system is fraught with inadequate personnel, weak logistics systems and poor service delivery. The Federal Ministry of Health (FMoH) report on mapping of partners’ procurement and supply management systems for medical products with its recommendations was evaluated. An assessment of Supply Chain Management (SCM) of health facilities as well as the different categories of personnel that manage them was conducted. The study indicated 79.5% of the facilities received free antimalarials, 46.2% received free ARV and 23.1% received free antituberculosis. Facilities (94.9%) were not involved in the product selection as it was undertaken by providers. Also, 65.4% of the facilities received expiring drugs, 87.2% did not have well trained and efficient staff. In addition, 88.5% admitted that supplies were sometimes delayed and they (65.4%) are usually not intimated of the reasons, 66.2% do not calculate average monthly consumption, 59.5% submit LMIS report monthly while 60.0% do not have inventory control system. The study indicated that stock out and supply interruptions still exist several years after FMoH survey and recommendations. This study found that logistic challenges still exist at the SDPs implying that either FMoH recommendations were not implemented or implementation was ineffective in addressing the challenges. Keywords: inventory management, logistics, procurement and supply management, supply chain management

Principles of electrical grid configuration management and tasks of their implementation

THE PURPOSE. To consider and analyze the definitions of the concepts "configuration of the electrical grid", "control of the configuration of the electrical grid ", "parameters of the configuration of the electrical grid ". To justify the need to manage the configuration of electrical grid, describe the principles and methods of managing the configuration of the electrical grid. To demonstrate the implementation of the principles of managing the configuration of the electrical grid on the example of an electrical grid with a nominal voltage of 0.4 kV with the use of proprietary technical configuration management tools. METHODS. Based on the literature review, the study identified the wording of key concepts, such as" configuration of the electrical grid"," management of the electrical grid configuration", "parameters of the electrical grid configuration". Methods of managing the configuration of the electrical grid are shown. The principles of electrical grid configuration management proposed by the authors are considered, which include observability, manageability, segmentability, flexibility of the electrical grid configuration, equipment intellectualization, and integration into the economy. The essence of each of the management principles is revealed and the effects of their implementation are shown. The effects of implementing the configuration management principles are to reduce the number of power supply interruptions and reduce the time of power supply interruptions to consumers, mismatch the quality parameters of the electricity supplied to them, as well as to increase the availability of electricity infrastructure. The rationale for the need to manage the configuration of electrical grid is given. Within the framework of the conducted research, the method of system analysis, methods of comparisons and analogies, and expert assessments were used. RESULTS. On the example of the scheme of power supply to consumers at a voltage of 0.4 kV, the implementation of the principles of control of the configuration of electrical grid with the use of proprietary technical means – multi-contact switching systems, input-accounting-distribution devices integrated into the monitoring systems of the parameters of the operating modes of electrical grid and other devices is illustrated. CONCLUSION. The implementation of the principles of configuration management of electrical grid allows to increase the efficiency of power supply systems for consumers and at the same time causes the need to develop new technical means of automation and monitoring of parameters of operating modes of electrical grids.

Power quality issues: Power supply interruptions as key constraint to development in Ekiti State, Nigeria

The power quality issues in the world today are critical to the development of different nations. Prosperity of each nation depends on availability of constant power supply and the quality of supply of power is very important to the required developments in world in the past, the present and the future. Constant power supply is a major challenge in Africa particularly in Nigeria where the generated power is less than thirty percent of the required power. The metrics of power quality are voltage sag, flickers, spikes, harmonics, notching, transients and interruptions. This paper reviewed power quality issues and the interruptions as they affect the development of the State. The level of interruptions in Ekiti State was thoroughly examined and the causes of power interruption in the State were investigated. The method used was the collection of data in respect of power interruptions on Ekiti feeders from the Benin distribution company, assessment of the collected data through simple programming as a command for plotting the graphs through the use of MATLAB 2015 depicting the behavioural pattern of the interruption for a period of six months in 2016. The result shows that the interrelationship between the interruptions and development particularly as it affects domestic consumers, small and medium scale enterprise adversely. Recommendations were suggested with the objective of solving the problems being set up by interruptions in the State and these include installation of reactors, automatic voltage regulators and effective tap changing system on the lines, busses and transformer substation respectively.

Dual-Source Procurement and Supplier Pricing Decision under Supply Interruption

The occurrence of major public health events usually leads to interruptions in the supply chain. This article studies the supply chain consisting of two suppliers and one manufacturer. In the case of supply interruptions, the manufacturer adopts two models of unit cost subsidies and proportional subsidies. The reliability of the supplier’s supply is incentivized and ensured. A Stackelberg game model is established in which the manufacturer is the leader and the supplier is the follower. The research results show that the optimal order quantity of the supplier manufacturer and the optimal wholesale price of the supplier will be affected by the reliability level, and the optimal supply chain profits of the two models under different parameters are compared.

The Eastern Baltic LNG Terminal as a Prospect to Improve Security of Regional Gas Supply

One of the crucial issues in Europe at the moment is securing reliable gas supply. Achieving security of gas supply implies diversifying gas sources, while having enough supply, transportation, and storage capacity to meet demand peaks and supply interruptions. In 2013, the Baltic States still remain disintegrated from the rest of Europe in one crucial way: their natural gas infrastructure isolates them into “energy islands”. The Eastern Baltic Sea European Union (EU) member states of Finland, Estonia, Latvia and Lithuania are the only ones which remain isolated from the present integrated EU natural gas transmission system. The gas demand in these isolated member states is approximately ten billion cubic meters (bm3) of natural gas per year. The third energy package of EU proposes a new series of measures to promote competition and create a single European energy market. Estonia, Latvia, Lithuania and Finland now for the first time have a chance to secure their energy independence by connecting their natural gas systems with those of their European allies and evolving them into market-based trading systems. Liquefied natural gas (LNG) is an important energy source that contributes to energy security and diversity, therefore a concept of a regional LNG terminal has been proposed. In this paper the authors give an overview of the current situation and present possible future scenarios with the development of Eastern Baltic regional LNG terminal. 2013 is a crucial time as in September the decision will be made regarding weather the regional LNG terminal will be chosen as a project of common interest in the trans-European energy networks.

Optimization-driven distribution of relief materials in emergency disasters

The distribution of relief materials is an important part of post-disaster emergency rescue. To meet the needs of the relief materials in the affected areas after a sudden disaster and ensure its smooth progress, an optimized dispatch model for multiple periods and multiple modes of transportation supported by the Internet of Things is established according to the characteristics of relief materials. Through the urgent production of relief materials, market procurement, and the use of inventory collection, the needs of the disaster area are met and the goal of minimizing system response time and total cost is achieved. The model is solved using CPLX software, and numerical simulation and results are analyzed using the example of the COVID-19 in Wuhan City, and the dispatching strategies are given under different disruption scenarios. The results show that the scheduling optimization method can meet the material demand of the disaster area with shorter time and lower cost compared with other methods, and can better cope with the supply interruptions that occur in post-disaster rescue.