Electrical Network Configuration Research Articles

Optimal electric distribution network configuration using adaptive sunflower optimization

Network reconfiguration (NR) is a powerful approach for power loss reduction in the distribution system. This paper presents a method of network reconfiguration using adaptive sunflower optimization (ASFO) to minimize power loss of the distribution system. ASFO is developed based on the original sunflower optimization (SFO) that is inspired from moving of sunflower to the sun. In ASFO, the mechanisms including pollination, survival and mortality mechanisms have been adjusted compared to the original SFO to fit with the network reconfiguration problem. The numerical results on the 14-node and 33-node systems have shown that ASFO outperforms to SFO for finding the optimal network configuration with greater success rate and better obtained solution quality. The comparison results with other previous approaches also indicate that ASFO has better performance than other methods in term of optimal network configuration. Thus, ASFO is a powerful method for the NR.

Optimisation of electrical network configuration: Complexity and algorithms for ring topologies

We consider power distribution networks containing source nodes producing electricity and nodes representing electricity consumers. These sources and these consumers are interconnected by a switched network. Configuring this network consists in deciding which switches are activated and the orientation of the links between these switches, so as to obtain a directed acyclic graph (DAG) from the producer nodes to the consumer nodes. This DAG is valid if the electric flow it induces satisfies the demand of each consumer without exceeding the production capacity of each source and the flow capacity of each switch. We show that the problem of deciding if such a valid DAG exists is NP-complete. In the case where such a valid DAG exists, we study the problem of determining a valid DAG that balances the ratio between the amount of electricity produced and the maximum production capacity for each source. We show that this minimization problem is also NP-complete in the general case but that it becomes polynomial in the case of ring network topologies.

Применение метода наложения для решения задачи определения места повреждения в сетях среднего напряжения

Medium-voltage networks are characterized by a long length and high degree of wear. Isolation of a failed network section requires significant time expenditures, a circumstance that makes accurate and fast determination of the fault location a topical problem. In view of specific features of emergency modes in medium voltage networks, the development of precise algorithms for fault location in the case of single and double ground faults involves certain difficulties. The arbitrary configuration of electrical networks, specific neutral grounding conditions, and lack of the possibility to perform multilateral measurements of emergency parameters complicate the development of universal fault location algorithms. In addition, technical solutions are as a rule limited by the need of using one-sided measurements of emergency mode parameters. The considered algorithms for calculating the distance to the fault location involve the use of emergency and normal electric network mode parameters. The proposed algorithms are based on using the superposition method and do not depend on the electrical network topology; they make it possible to decrease the influence of the current distribution pattern in lines with branches, as well as the influence of the load operating conditions on the accuracy of calculating the distance to fault location. The application of the proposed algorithms is justified by the results of simulation and makes it possible to calculate the distance to the fault location in networks with insulated neutral with high accuracy.

Optimization of electric distribution network configuration for power loss reduction based on enhanced binary cuckoo search algorithm

This paper presents a new network reconfiguration (NR) method using enhanced binary cuckoo search algorithm (EBCSA) to reduce power loss in the distribution system. Enhanced binary cuckoo search algorithm (EBCSA) is developed by transferring the continuous cuckoo search algorithm (CSA) to the binary domain and adding a new local search mechanism. Calculation results on different test systems demonstrate that EBCSA has capability for searching the optimal network configuration with greater success rate, better optimal solution quality and smaller number of average convergence iterations than those of binary CSA, binary coyote optimization algorithm, binary genetic algorithm and binary particle swarm optimization. Furthermore, the effect of the transfer function transferring from continuous domain to binary domain and the value of the parameters of EBCSA for the NR problem are also evaluated to choose the suitable values. The results show that EBCSA is a tool worth considering for the NR problem.

Incorporación de Generación Renovable y Segmentación de Redes Eléctricas

En el presente trabajo se desarrolla una metodología que facilita la transición de una red eléctrica centralizada tradicional a una configuración de red eléctrica basada en microredes. Se incorporan generadores inyectando potencia en posiciones estratégicas de la red. Además, partiendo de la topología de una red radial centralizada, se delimitan microredes con el propósito de otorgarles la mayor capacidad para que puedan funcionar de forma aislada. Esta optimización se realiza considerando la minimización de las pérdidas de la red y maximizando la autonomía potencial de las microredes obtenidas. Para desarrollar la metodología propuesta, se emplea recocido simulado como algoritmo metaheurístico de optimización.

Solid Oxide Fuel Cell Energy Conversion Networks

A powerful electrical network analyzer, PSpice, is used to explore alternative solid oxide fuel cell Energy Conversion Networks (ECN’s). The ECN’s electrical network configurations are important in determining where solid oxide fuel cells can best play in modern grid support and resiliency. A modeling methodology is used to relate microscopic solid oxide fuel cell solid-state ionic material properties like electrical conductivity to macroscopic solid oxide fuel cell Energy Conversion Networks’ electrical network performance. While many models could be used for the ECN components, such as fuel cells, storage, etc., the model chosen in this paper as an example to illustrate the methodology, allows heat engine component performance, when included, to be recast solely in electrochemical and electrical network terms. The analysis results in this paper include the power and efficiency responses of the ECN’s of interest, such as multiple solid oxide fuel cells in multi-loop electrical networks, smart grids and microgrids.

Research of the possibility of application of the superposition method for implementation of algorithms for determining damage locations in networks with isolated neutral

It is difficult to develop precise algorithms for determining fault locations for single-phase and double earth faults due to the features of emergency modes in medium voltage networks of 6-35 kV. The arbitrary configuration of electrical networks complicates the development of universal fault locations algorithms and, as a rule, technical solutions are limited by the need to use one-way measurements of emergency mode parameters. The article discusses new topology independent fault location algorithms that involve the use of the superposition method. The application of the proposed algorithms is justified by the results of simulation modeling and will allow implementation of calculating the distance to the fault in networks with isolated neutral with high accuracy.

MULTIPLE AGENT MANAGEMENT BY DISTRIBUTION ELECTRIC NETWORKS OPTIMAL DISPATCH

Solving the problem of management intellectualization is complicated by the large dimensionality and branching distribution network, low monitoring of its regime and limited set of adaptive management measures. Introduction the SmartGrid concept in modern distribution power networks makes it unnecessary to solve the problem of adaptation the topology of the working scheme to the electricity transmission mode current conditions in real time. The paper substantiates the special urgency of the problem of closing closed circuits in modern heterogeneous electrical networks, which are maintained by operators of electric networks of different hierarchical levels. Known methods of optimization disconnection of electrical networks provide a centralized approach to the relevant control systems that practically impossible to implement optimal commutation switching in real time. Therefore, it is expedient to use a decentralized approach, based on the principles of multi-agent management of the distribution grid. Obviously, operative optimization of the places of unplugging of distributive electric networks will cause the improvement of the quality of electric energy by voltage deviation. This situation has fallen to the basis of the developed mathematical apparatus supporting decisions by the multi-agent system of operational reconfiguration of distribution electrical networks. The proposed approach to the formation of a multi-agent control system for the configuration of distribution electrical networks is illustrated in the scheme of heterogeneous electrical networks 110-750 kV of the Southern power grid of UPS Ukraine. It is stated that the opening of circuits 110 (150) kV will result in decrease of active power losses by 9.5%, and energy losses during the year is approximately 8%. The operational adaptation of the working circuit of distribution networks further reduces energy losses by 3-5% during the year.

An improved cuckoo search algorithm for the problem of electric distribution network reconfiguration

Power loss reduction has an important role in operating electric distribution network system. There are a lot of methods for reduction power loss such as capacitor placement, distributed generation placement and electric distribution network reconfiguration (EDNR). Among these methods, the EDNR is an efficient technique to reduce power loss due to without taking any costs. However, the EDNR problem is a nonlinear, discrete problem and lots of extreme points. Therefore, it is necessary to have efficient methods for solving the EDNR problem. In this paper, an improved cuckoo search algorithm (ICSA) is proposed for solving the EDNR problem. In which, based on disadvantages of exploration and exploitation process of cuckoo search algorithm (CSA) for solving the EDNR problem, a local search mechanism is added to exploit candidate solutions existing around the current best solution. The calculated results on the simple distribution networks to complex distribution networks show that ICSA has ability for finding the global optimal solution with much smaller iterations and better quality of obtained solution compared with CSA and some other improved versions of CSA. The performance comparisons with other existing methods available in previous studies and the software of Power System Simulator/Advanced Distribution Engineering Productivity Tool (PSS/ADEPT) also lead to the better electric distribution network configuration with smaller total power losses. As a result, ICSA is a potential and reliable method for solving the EDNR problems.

Development of Optimum Repair Schedule of Electrical Network Equipment to Improve the Reliability of its Functioning

To ensure uninterrupted power supply to consumers, maintenance of the electrical networks in a working condition is today carried out through the use of a system of preventive maintenance. In the general case such a system allows building equipment repair schedules based on repair cycles for a long time predetermining the list of necessary material and labor resources in advance. However, in practice, the use of this system is rather difficult and not always effective. This is due to the need to change the repair schedule for emergency or urgent repairs taking into account the seasonality of work performed and the organizational structure of the production department of electrical networks and related departments as well as taking into account the specific features of the operation of specific equipment. Taking into account the current pace of development of electrical networks with a steady increase in the number of consumers (which also leads to a complication of the configuration of electrical networks) this is impossible without the use of appropriate mathematics and software that automates the planning processes for the maintenance and repair of electrical networks with a large number of factors. The minimum equipment downtime was taken as the main criterion for optimality, as a factor that largely determines the reliability of power supply. A planning algorithm has been developed that takes into account the ranking of works in order of importance, the possibility of their shift in time and the likely adjustment of the schedule based on the results of assessing the technical condition of the equipment. A method for minimizing the downtime of repair crews by using them in adjacent areas as well as a technique for identifying a set of equipment that may be under repair in the same period of time are proposed.

OPERATIONAL ACTIVITIES FOR ACHIEVING ENERGY EFFICIENCY IN ELECTRICAL NETWORKS

The energy efficiency improvement actions of the electrical networks are divided into two main groups: operational and technical. Technical events require significant investment. Operating events do not require investment and are limited to optimal solutions in operational conditions that achieve energy efficiency. The report presents a methodology for assessing of the energy efficiency when changing the configuration of distribution electrical power networks. It is summarizing the results of the reconstruction and exploitation of the distribution networks for medium and low voltage under optimized schemes, which achieve energy efficiency. Recommendations are made for the implementation of energy efficiency activities in the exploitation of distribution networks.

‘HVDC optimisation’ – driving down the cost of large‐scale offshore wind

The cost optimisation of 1-GW offshore wind farms is investigated in this study. The feasibility of combining AC collector platforms and an HVDC converter platform to form a combined platform is assessed. The evaluation of different electrical connection topologies is undertaken for a wide range of different electrical network configurations that lend themselves to consolidating the number of offshore platforms to reduce capital expenditure and operational expenditure, in order to arrive at a single preferred design option for further optimisation. Both quantitative evaluation based on project net present value and qualitative evaluation of technological aspects such as losses, availability, control/interface, technical complexity and project delivery aspects such as fabrication, yard capacity, transportation and installation are undertaken and ranked.

Исследование резонансных явлений в распределительных электрических сетях среднего напряжения систем внутризаводского электроснабжения промышленных предприятий

At present there is a tendency in the metallurgical industry to build mini-factories with a capacity of 1 to 2 million tons of steel per year. The largest supplier of technological equipment of such plants is the company Danieli (about 80% of the world's total). The main advantages of these factories are: combining ultra-compact sizes and high technologies with reduced in-vestment costs, extremely low cost of transformation, and also high ecological purity. That is why the demand for the construction of mini-plants is growing. In internal power supply systems of metallurgical mini-factories with an average produc-tion volume (1-2 million tons of steel per year) medium-voltage extended distribution networks of 6-35 kV are used. With a long length of cable lines, the total value of the distributed capacity of the cables can reach several microfarads. As a result of the interaction of an inductance of a network transformer and the capacitances of the cables in the frequency characteristic of the network, a resonance of the currents arises, the amplitude of which, with a large value of the cable capacity, can be located in the frequency range of higher harmonics generated by modern frequency converters with AR. In this case, there are strong high-frequency voltage distortions on the 10 kV BUS BARS, which can lead to the bread down of frequency converters due to errors in the operation of the control pulses forming units of power switches AR. For this reason, the actual task is to investigate various ways to eliminate resonances of current in the frequency characteristic of the power supply network, as well as strong distortions. The paper deals with investigations of the causes of high voltage distortions in the 10 kV grid of internal power supply of metallurgical enterprises, where powerful electric drives of rolling mill stands are built on the basis of multilevel frequency converters with active rectifiers installed. The processing of the experimental data was carried out in the Matlab - Simulink application, where the main coeffi-cients of the harmonic voltage components of the 10 kV network were calculated using by spectral analysis methods and developed signal processing algorithms. To study the methods of correcting the frequency response of a 10 kV network the mathematical modeling of the system of internal power supply was used. Currently, this problem is poorly understood and poorly covered in Russion and foreign literature. In this regard, the results of the research presented in the work have novelty, theoretical and practical significance. The main result of the research is the recommendation to eliminate current resonance by means the special connection R-L filter based on capucity banks and low inductance reactor with reactance about 100 ?H. The results of the research can be used in the design of power supply systems for industrial enterprises to implement the cor-rect choice of the configuration of medium voltage electrical networks, as well as in solving power quality problems at operating plants where strong high-frequency voltage distortions occur during the operation of powerful FC and AR

A Comparative Study on Power System Harmonics for Offshore Plants

The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.

Определение предельных параметров режимов для обеспечения успешной ресинхронизации объектов распределенной генерации в условиях предприятия черной металлургии

Development of distributed generation units and complication of electric network configuration result in growing number of possible emergency modes of industrial power supply systems. The plant and some consumers switch to separate operation at short circuits of the power supply system or frequency drop in the supply network. After the damaged lines have been switched off, automatic resynchronization of the network node is required. The algorithm for calculating transient electromechanical processes in industrial power supply systems has been developed to investigate these emergency modes. Based on the above algorithm, the authors have elaborated a software package to explore these electromechanical modes. As switch to a separate operation is possible with various power supply and load configurations, the methods determining the limit power imbalances at the set time of automatic reconnection have been obtained. Experiments were carried out at the industrial power plant including different power generators that provide energy-intensive industrial load. Developed activities will increase sustainability of this power supply system. The proposed software package can be used as an advising tool for control engineers to increase mode management efficiency of auxiliary industrial power plants.

A Markov Decision Model for Cooperative Virtual Power Plants Market Participation

The advent of renewable energy induces new problematic electrical network configurations. Indeed, the renewable energy characteristics (intermittency, production uncertainty) combined with their inherent spatial distribution implies to aggregate them and to design specific control tools to connect them to the grid and allow them to participate to the market. Based on an industrial case study, we propose in this work to gather and coordinate numerous independent producers through a Cooperative Virtual Power Plant (CVPP). To perform an efficient market participation of such coalition of producers, we model its behavior as a Markov Decision Process. Our model takes into account renewable generation prior uncertainty, market constraints and optimizes sequentially the utilization of available resources. Experiments realized using realistic datasets show the efficacy of the proposed model and speak in favor of renewable and controllable producers’ coalition in CVPP.

A Mixed-Integer Linear Programming Approach for the Computation of the Minimum-Losses Radial Configuration of Electrical Distribution Networks

The paper deals with the solution of the minimum-losses configuration problem of distribution networks including embedded generation by means of a mixed-integer linear programming (MILP) model. A model is proposed that takes into account the typical operating constraints of distribution networks (radial configuration, branch ampacity limits, and bus voltage requirements) and the presence of embedded generation. The accuracy of the results and the computational performances of the proposed MILP model are evaluated by using test networks already analyzed in the literature for the problem of interest.

Probabilistic life cycle analysis model for evaluating electric power infrastructure risk mitigation investments

One effect of climate change may be increased hurricane frequency or intensity due to changes in atmospheric and geoclimatic factors. It has been hypothesized that wetland restoration and infrastructure hardening measures may improve infrastructure resilience to increased hurricane frequency and intensity. This paper describes a parametric decision model used to assess the tradeoffs between wetland restoration and infrastructure hardening for electric power networks. We employ a hybrid economic input–output life-cycle analysis (EIO-LCA) model to capture: construction costs and life-cycle emissions for transitioning from the current electric power network configuration to a hardened network configuration; construction costs and life-cycle emissions associated with wetland restoration; and the intrinsic value of wetland restoration. Uncertainty is accounted for probabilistically through a Monte Carlo hurricane simulation model and parametric sensitivity analysis for the number of hurricanes expected to impact the project area during the project cycle and the rate of wetland storm surge attenuation. Our analysis robustly indicates that wetland restoration and undergrounding of electric power network infrastructure is not preferred to the “do-nothing” option of keeping all power lines overhead without wetland protection. However, we suggest a few items for future investigation. For example, our results suggest that, for the small case study developed, synergistic benefits of simultaneously hardening infrastructure and restoring wetlands may be limited, although research using a larger test bed while integrating additional costs may find an enhanced value of wetland restoration for disaster loss mitigation.

Optimización de Redes Eléctricas Mediante la Aplicación de Algoritmos Genéticos

This work proposes the optimization of the topological configuration of secondary electrical distribution networks to minimize technical losses produced during their exploitation due to Joule effect, using for this Genetic Algorithms. Through the application of the method to two systems, it was found that the optimization technique is able to find the optimum solution among all the possible combinations that switch operations offer. Its flexibility to adapt to the restrictions of radiality and voltage level in less time than that of exhaustive search is also proved. During the development of the application the genetic operators were validated, determining those that gave the best performance in the search of the solution. The results show the feasibility and viability of the application for the optimum configuration of electrical distribution systems.

An overview of present trends in energy management systems development

This paper starts with a brief overview of the situation in the electrical industry, with regards to electrical network configurations and operational Energy Management Systems. A concise description is provided of the network control levels, the transfer from electromechanical control to computer based control, and the types of centre-centre communication involved. The electrical utilities requirements on new systems are then discussed, not as just another «new functional specification for controlling the process» but from the point of view of second generation requirements on computer systems from a group of users now conversant with the application of computer techniques to their industry