Electrical Energy Supply System Research Articles

Verification of the uninterrupted transition from grid parallel to island grid operation of the Virtual Synchronous Machine in a microgrid

The classic energy supply system is mainly based on the stabilising properties of electromechanical synchronous generators. The structural change of the electrical energy supply system towards a decentralised grid structure means that ancillary services must now also be provided at the distribution grid level. The Virtual Synchronous Machine (VISMA) was developed at the Institute of Electrical Power Engineering at the Clausthal University of Technology with the aim of making a decentralised generation unit in the grid behave like a real synchronous machine and thus actively provide relevant ancillary services. The VISMA is based on a three-phase inverter that can comply with grid requirements by adding an energy storage device in the DC link and using a special control algorithm. The focus of the investigations shown here is on the uninterrupted transition from grid-parallel operation of the VISMA to island grid operation and the subsequent stable continued operation of this island grid. A controller changeover, as most feed-in inverters would require in order to change the operating mode, is not necessary here. It is shown that the transients have subsided after 5 ms, which means that the VISMA has completely taken over the

Change Character of Electric Conductive Properties of Weeds Plants Tissue at Electric Impulse Damage

Currently, in order to obtain pre-planned results and increase the efficiency of using existing technologies, electrotechnological operations are applied in the processes of agricultural production, food and processing industries, including those that implement the effects of high voltage impulses. One of such promising technologies in agriculture can be considered to be electric impulse weeding that is the fight against unwanted and weed vegetation. Such operation, which is carried out with high rates of technological efficiency, is environmentally friendly and refers to high-tech processes. For practical applications and technical implementations, it is necessary to study various properties and parameters of effected objects – weeds. The partial dependence of the electrical resistance of the plant tissue or the dispersion of resistance over the frequency of the measuring current was decided to be used as the studied characteristic. This approach allows to consider weeds not only as a load with which the electrical energy supply system is in contact but also to thoroughly study how this resistance changes during processing. The conducted experimental studies made it possible to clarify the nature of the change in resistance under the damage process to plant tissue, as well as to estimate the quantitative indicators of both the energy absorbed by the plant tissue and the ranges of variations of its resistance. The change character in the plant tissue resistance at the process of the electrical impulse damage remains unchanged, only the resistance value at low frequencies decreases. The total damage corresponds to the period of processing when the resistance of the plant tissue is practically equal at low and high frequencies. This behavior of the mentioned parameter is typical for internal and surface tissues of weeds, as well as for their root systems and leaf-stem parts. Theoretical verification of the change character in the plant tissue resistance of destroyed weeds confirmed the description of the proposed mechanism of change in resistance in the process of irreversible electrical impulse damage.

Rural Household Space Cooling and Lighting through a Solar Power-based Electric Supply System

Quite a number of households in the world still lack electricity, especially in the sub-Saharan African continent. However, the abundance of solar irradiation in tropical Africa can be advantageously exploited to serve the inhabitants in this region, particularly the extremely low-income earners who not only have access to very inadequate power supply but also experience much discomfort in terms of poor ventilation and heat-triggered infections. This paper focuses on developing a small household-sized solar power-based electric energy supply system together with a temperature control circuit to power a direct current (DC) fan, and a light-regulating circuit to control LED lamps—with additional features such as a digital clock, a remote control, and mobile phone charging units. The system also has a provision for power supply through the mains (whenever it is available). The overall intent is to provide the rural dwellers with a cost-effective way of powering essential devices for basic economic living. This affordable solution is designed, simulated, and constructed to have hardware and software sections supported by various components and devices such as Arduino Mega, Lm35 sensor, RF transceivers, diodes, transistors, regulators, batteries, lamps, a DC fan, etc. The sensor senses room temperature, which is compared with the reference temperature of 25°C programmed on the Arduino microcontroller. When the temperature is less than 25°C, the fan remains stationary but when the temperature is higher than the reference value, the fan begins to run. As the temperature rises further, the speed of the fan increases to maintain adequate ventilation.

Coronavirus, infrastructures and the sociotechnical (dis)entanglements in Brazil

The text provides an analysis of the disorganization of large sociotechnical networks and infrastructure in Brazil, due to the coronavirus epidemic. Special attention is paid to the entanglement of infrastructural networks, such as the health system and the electrical energy supply system in the country. The effects of COVID-19 in economic activities and in some key social dynamics cause disorganization in these and other sectors, in levels rarely seen, and in doing so provide evidence of how they are entangled. The concept of disentanglement is proposed, as a development of the widely employed concept of entanglement in the social sciences.

Smart grid planning method based on multi-objective particle swarm optimisation algorithm

Smart grid refers to a modern electric energy supply system to tackle a lot of problems in grid management, such as, resource shortage, environment pollution and so on. In this paper, we propose a novel smart grid planning method using multi-objective particle swarm optimisation algorithm. The goal of smart grid plan is to calculate the minimum investment and annual operating costs, when we obtain the planning level of load distribution, substation capacity and power supply area to satisfy the load requirement and optimised substation location. Afterwards, we propose a multi-objective particle swarm optimisation algorithm which integrates the estimation of distribution algorithm. Furthermore, the propose approach divides the particle population into a lot of sub-populations and then build probability models for each population. Finally, experimental results demonstrate that the proposed method can effectively arrange new substation, which is able to make up for deficiencies of current existing substations.

The Impact of Hydropeaking on Juvenile Brown Trout (Salmo trutta) in a Norwegian Regulated River

The Norwegian electrical energy supply system is based on hydropower. The now deregulated energy market has led to increased use of hydropeaking production, leading to greater fluctuations in discharge and water levels below hydropower stations. The power station HOL 1, with an outlet to the Storåne River, is a large hydropeaking facility. With over 300 rapid flow increases and decreases per year since 2012, it is a river subjected to frequent hydropeaking. To quantify the stranding risk downstream of the power plant, the effect of a series of different turbine shutdown scenarios was simulated in an earlier study. The residual flow of 6 m3·s−1 and a full production of 66 m3·s−1 were considered as the baselines for the calculation of dewatered areas. A three-year study of juvenile fish density both upstream as a reference and downstream of the power plant was undertaken. There were very low densities or even an absence of brown trout (Salmo trutta) older than young-of-the-year (YoY) below the outlet of the power station, despite high densities of YoY in previous years. This is probably due to the large and rapid changes in flow below the power station. Hydropeaking has less impact on the earliest life stages of brown trout during spring and summer, as well as on spawning and egg development during winter. This is attributed spawning in late autumn occurring at a low flow seldom reached during hydropeaking. The high survival of YoY during the first summer and early autumn is likely due to a lower frequency of hydropeaking and higher residual flows, leaving a larger wetted area.

State Estimation for DC Microgrids using Modified Long Short-Term Memory Networks

The development of state estimators for local electrical energy supply systems is inevitable as the role of the system’s become more important, especially with the recent increased interest in direct current (DC) microgrids. Proper control and monitoring requires a state estimator that can adapt to the new technologies for DC microgrids. This paper mainly deals with the DC microgrid state estimation (SE) using a modified long short-term memory (LSTM) network, which until recently has been applied only in forecasting studies. The modified LSTM network for the proposed state estimator adopted a specifically weighted least square (WLS)-based loss function for training. To demonstrate the performance of the proposed state estimator, a comparison study was done with other SE methods included in this paper. The results showed that the proposed state estimator had high accuracy in estimating the states of DC microgrids. Other than the enhanced accuracy, the deep-learning-based state estimator also provided faster computation speeds than the conventional state estimator.

A safe, reliable and regenerative electrical energy supply to power the future

Today, three phenomena are developing into critical global problems, requiring urgent attention from leaders all over the world. The first of these is the increase in carbon dioxide (CO2) emissions due to the escalated use of coal, resulting in the gradual increase of the Earth’s average temperature. The second is the continually diminishing fossil fuel resources, e.g. oil and natural gas, which are the primary sources of energy for vital services like transportation and domestic heating. The third is the unforeseen and rapid “world population boom” since the beginning of the 19th century after the invention of the steam engine by JamesWatt. The combination of these three factors signal imminent danger. With the increase of the world population, there is a subsequent rise in the usage of both electrical and non-electrical types of energy. At the same time, not only are the sources of these energy forms, i.e. the fossil fuels, depleting because they are non-renewable but their usage is also severely detrimental to the environment. Therefore, it is of utmost importance to reduce the dependence on fossil fuels and switch to renewable or even nuclear resources as alternatives, in order to prevent an impending climate disaster. Hence, taking the aforementioned problems into account, a method is proposed in this paper to create a safe, reliable and regenerative electrical energy supply system using renewable wind and solar energy as well as hydrogen storages.

Wind Turbine Electrical Energy Supply System for Oil Well Heating

In this article, the authors reviewed a new technology to prevent the formation of asphalt-resin-paraffin deposits by the thermal method of electrothermal impact on the oil wellbore shaft using a wind-electric installation as an autonomous power source. The advantage of this thermal stimulation technique lies in its continuous nature, which will allow keeping the clear opening of the tubing constant. The scheme of the autonomous system for down-hole electric heating of oil is presented. A tubular or induction heater can serve as an electric heating element placed in the well. The heating element of the system can be used in the wells exploited by freeflow, gas lift and mechanized methods, while its installation does not require an overhaul. The paraffin oil saturation temperature and temperature distribution over the depth of the well were defined. The amount of heat, which must be transferred to the oil mixture in the tubing in order to ensure effective operation of the well, taking into account the dynamic state of the system, is calculated. The optimal depth of the heating element's location in the well and its power was determined. The calculation of the required power for wind-electric installation to maintain the set temperature in the wellbore was performed. Having conducted the studies, it was revealed that in order to prevent the asphalt-resin-paraffin deposits formation on the tubing walls of oil wells, it is expedient to use the in-line heater, which maintains the average steady-state temperature along the wellbore and at the wellhead above the initial crystallization point of the asphaltresin-paraffin deposits. The application of the developed electrothermal system is relevant in the conditions of formation of asphalt-resin-paraffin deposits in the wellbore shaft at the fields, which do not have a connection to the centralized power grid.

Анализ аварийности и причин выхода из строя конденсаторных установок в системе электроснабжения нефтегазодобывающего месторождения

Анализ аварийности и причин выхода из строя конденсаторных установок в системе электроснабжения нефтегазодобывающего месторождения

System analysis and approaches to the developement of the automated electrical energy consumption and supply system of the food industry enterprise

System analysis and approaches to the developement of the automated electrical energy consumption and supply system of the food industry enterprise

Promises and limitations of nuclear fission energy in combating climate change

The most serious problem facing humanity is that we have only a few decades in which to implement effective measures to stop global warming. For these years up to about 2065, fission energy from light water thermal reactors is relevant as an available, developed and proven non-carbon technology with the potential to make an essential contribution to the mitigation of global warming, in addition to renewable energy. Nuclear power is expected to have more economic advantages than intermittent renewable sources for generating base load electrical energy requirements. This would be especially important in the years from about 2025 up to 2065, during which one cannot expect a serious contribution from nuclear fusion and even less from fossil fuels with carbon capture and storage (CCS) facilities. In a strategy to eliminate all non-CCS coal power stations, some 1600 MW of nuclear power would be required and sufficient to cover the base load for the electrical energy supply system. This nuclear expansion should be accompanied by effective international safety assurances, including a mandate to stop construction of unsafe nuclear power plants. In the long term, after 2065, we expect inherently safe molten salt thorium reactors to compete with fusion reactors.

Power Re-Dispatch Reduction with Nodal Voltage Angle Control in Electrical Energy Supply Systems

Abstract In the future, the electrical power supply networks will be transformed from conventional power plant structures with inertia to a complete inertia independent system. Such systems will include storages for different generation speed together with power electronic converters. In this paper, a novel method is proposed to control the electrical power distribution by these new power plants. All the control principles necessary involving spinning reserve, primary control and secondary control depending on frequency are substituted by a comprehensive angle control of the nodal voltages in the transmission and distribution network. It is observed that whenever the power requirement of the loads increase, the slack generators satisfy this rising demand with the power stations closest to the point of increasing consumption automatically producing the most power. This drastically reduces the heavy load flow and the need for general power re-dispatch measures. Reducing power re-dispatch would not only save millions of Euros on an annual basis but also lead to the formation of a more secure electrical network.

A Mean Field Game Theoretic Approach to Electric Vehicles Charging

Electric vehicles (EVs) provide environmentally friendly transport and they are considered to be an important component of distributed and mobile electric energy storage and supply system. It is possible that EVs can be used to store and transport energy from one geographical area to another as a supportive energy supply. Electricity consumption management should consider carefully the inclusion of EVs. One critical challenge in the consumption management for EVs is the optimization of battery charging. This paper provides a dynamic game theoretic optimization framework to formulate the optimal charging problem. The optimization considers a charging scenario where a large number of EVs charge simultaneously during a flexible period of time. Based on stochastic mean field game theory, the optimization will provide an optimal charging strategy for the EVs to proactively control their charging speed in order to minimize the cost of charging. Numerical results are presented to demonstrate the performance of the proposed framework.

Conceptual framework for integrated strategic planning and development of electrical energy supply and delivery system

This paper provides a conceptual integrated strategic energy planning and development framework for host countries with the ultimate goal of achieving sustainable and climate-friendly energy systems. The conceptual planning framework links up energy planning goals, inputs/outputs and resources, economic/regulatory/technological strategic initiatives, and energy system value chains. The paper examines linkages and interactions between the aforementioned planning modules and proposes implementation process and planning directions for different stages of a country's development. The paper ends with an empirical study on Hong Kong electricity supply industry that deems compatible with the conceptual framework.

리튬폴리머 전지의 전기적 모델링

전기 장치용 리튬폴리머 전지의 전기적 모델링은 전기에너지 공급시스템의 특성을 파악하는데 매우 중요하다. 본 논문은 리튬폴리머 전지의 동적특성을 모사하기 위한 전기적 등가 모델을 제안하였다. 리튬폴리머 전지의 충/방전 실험은 Maccor 8500 충방전시험장치를 사용하였다. 측정된 데이터를 이용하여 전지의 R-C 값을 선정하였으며, 선정된 값은 다항식 함수와 지수 함수를 사용하여 수식으로 나타내었다. 시뮬레이션 결과와 실험결과를 비교하여 제안된 모델의 타당성을 검증하였다 Electrical modeling of lithium-polymer battery is very important for electric energy supply system. In this paper, electric equivalent circuit of lithium-polymer battery is proposed to simulate its dynamic characteristics. Maccor 8500 charge/discharge system is used to obtain the experimental data of lithium-polymer battery. Model parameters are calculated by using Matlab. This paper defines a R-C model for charging/discharging of battery and polynomial functions are used for OCV (Open Circuit Voltage) modeling. The proposed model is simulated with PSiM and then compared the simulation results with the experimental results to verify the validity of the proposed model.

Computer Aided Design Tool For The Study OfElectric Traction Fixed Installations And TrainOperation

The complexity in design and dimensioning of electric traction fixed installations necessitates the development of a methodology for dimensioning based on numerical simulation models. This solution gives faster and more reliable results than those obtained by the empirical and inaccurate methods previously used. A computer aided design tool implementing this methodology is presented in this paper. Various elements such as truck data, catenary, traction substations, rolling stock, train composition, railway network and schedule conditions are considered. The analysis of the resulting simulated output allows optimisation and selection of the best solution for the power supply system of a railway network, as far as traction substations and overhead line systems are concerned. Therefore, the final choice of the electrical energy supply system that fulfils the technical requirements and ensures the programmed traffic, should be submitted to the analysis of a minimum cost criterion, regarding available feeding points of the energy supplier network.

都市環境の保全と分散エネルギーシステム

都市環境の保全と分散エネルギーシステム