Efficiency Of Distribution System Research Articles

Comparison of Efficiency-Based Optimal Load Distribution for Modular SSTs with Biologically Inspired Optimization Algorithms

The battle of currents between AC and DC reignited as a result of the development in the field of power electronics. The efficiency of DC distribution systems is highly dependent on the efficiency of distribution converter, which calls for optimized schemes for the efficiency enhancement of distribution converters. Modular solid-state transformers (SSTs) play a vital role in DC distribution networks and renewable energy systems (RES). This paper deals with efficiency-based load distribution for solid-state transformers (SSTs) in DC distribution networks. The aim is to achieve a set of minimum inputs that are consistent with the output while considering the constraints and efficiency. As the main feature of modularity is associated with a three-stage structure of SSTs, this modular structure is optimized using ant lion optimizer (ALO) and validated by applying it to the EIA (Energy Information Agency) DC distribution network which contains SSTs. In the DC distribution grid, modular SSTs provide the promising conversion of DC power from medium voltage to lower DC range (400 V). The proposed algorithm is simulated in MATLAB and also compared with two other metaheuristic algorithms. The obtained results prove that the proposed method can significantly reduce the input requirements for producing the same output while satisfying the specified constraints.

Design of a Control System Using an Artificial Neural Network to Optimize the Energy Efficiency of Water Distribution Systems

Design of a Control System Using an Artificial Neural Network to Optimize the Energy Efficiency of Water Distribution Systems

Development of optimal pump schedules for improved energy efficiency in water supply systems (case of NWSC)

The water utility in Uganda (NWSC) was under pressure from regulators, environmentalists and board members to reduce energy costs. However, achieving energy efficiency in the water distribution systems of Kampala that is characterized by variable demands and prescribed pressures would be impossible if this utility continued operating on trial and error methods. This research was undertaken in the year 2016-2017 and aimed at exploring how pump schedule optimization could enable NWSC to deal with the challenge of high energy costs and improve water utility performance. In this research, the energy consumption of existing pumps was obtained from historical data, data was diagnosed and based on the diagnostic findings, decision variables were selected and optimal pump schedules were formulated. The formulated schedules were applied to the Gabba Muyenga supply system of National Water and Sewerage Company (Uganda) as a proof of concept. The formulated pump schedules when applied on different pumps classified as models 1, 2 and 3 based on pump flow ratings and motor voltage ratings, results show that scheduling pump operations based on time of the day tariffs enabled NWSC to save about 0.373 Million kWh annually. On the other hand pump scheduling based on pressure, modulation had the potential to reduce water losses enabling NWSC to save 12 m3/hr equivalent to 0.068 million kWh per year in energy terms without compromising customer service levels and this was only for the established DMA within the case study area and not for the entire NWSC water distribution network. The data presented were obtained through field measurements, statistical analysis and hydraulic design calculations

Information gap-based scheduling strategy of a multi-energy retailer with integrated demand response program

• Modeling a multi-energy retailer in the framework of multi-carrier energy systems. • Developing a multi-energy retailer based on gas/cooling/heating/power carriers. • Presenting an IGDT method to cope with uncertainties in the optimization model. • Integrating flexible options, e.g. hybrid energy storage in the optimization model. • Proposing integrated DR to control multiple energy demands simultaneously. Multi-energy systems (MESs) were introduced to enhance the flexibility and efficiency of conventional energy distribution systems. In this new trend, it is possible to supply different energy carriers simultaneously by the multi-energy retailer (MER), under which, without the need to transfer all of them to different locations, the loads are fed centrally, and the customers can purchase all the carriers they need from the desired MER. Motivated by these descriptions, this paper focuses on the optimal scheduling of MER in the integrated energy system, including natural gas, electricity, cooling, and heating, under the information gap decision theory (IGDT) framework. The MER's goal is to maximize profits by considering the uncertainty of the day-ahead power market. The proposed IGDT approach without a probabilistic distribution function analyzes the risk-aversion strategy associated with electricity price uncertainty. In this paper, integrated demand response (IDR) for natural gas, electrical, heating, and cooling loads are developed simultaneously as a flexible demand-side management resource. The proposed model contains multiple technologies owned by MER, including hybrid energy storage technology, combined heat and power, chiller, boiler units, and renewable resources. Numerical results from different cases illustrate the effectiveness of IDR installation in terms of profitability. Besides, the MER can serve multiple demands more efficiently. Under the IGDT approach, the purchasing power cost is reduced up to 24.23%.

Development of DSTATCOM Optimal Sizing and Location Technique Based on IA-GA for Power Loss Reduction and Voltage Profile Enhancement in an RDN

The efficiency of electrical distribution systems is being more affected by the increase in voltage drops and power losses. These issues of voltage drop and power loss can be significantly minimized by the incorporation of a Distribution Static Compensator (DSTATCOM) in the distribution network. However, inappropriate positioning and sizing of DSTATCOM can undermine its efficiency. Despite the contributions of many researchers to the optimal placement of DSTATCOM and other compensators in distribution networks, the problems of voltage drop, power losses, and power quality persist, necessitating the need for additional research in this area. In this paper, an innovative technique based on hybridized Immune and Genetic Algorithm (IA-GA) for optimal DSTATCOM placement and sizing for three distinct load levels is proposed. Simulation and analysis of the proposed algorithm were carried out using IEEE-33 bus radial distribution network (RDN) in MATLAB. The simulation results demonstrate a substantial decrease in power loss and a significant improvement in the voltage profile. Evaluation of the proposed method against existing techniques reveals that the proposed technique outperforms IA and PSO in terms of decreasing power loss and enhancement of voltage profiles. A cost-benefit analysis was performed, and it was discovered that the proposed technique yields improved annual cost savings.

Household dependence on fish-based farming systems in the Bons Sinais Estuary in Mozambique

Households in estuarine deltas of the Western Indian Ocean depend on small-scale fishing, farming in flood-recession and adjacent areas, and mangrove forest products for food security, energy and an income in so-called deltaic fish-based farming (FBF) systems. It was hypothesized that the relative importance of household activities would depend on location along the Bons Sinais Estuary in Mozambique, diversifying in peri-urban settings. Semi-structured interviews were undertaken at five sites, including rural sites near the estuary mouth and upstream, and peri-urban settings near Quelimane city. Fishing contributed the most to FBF livelihoods (54 %) followed by farming (15 %), small business operators (14 %), collection and use of mangrove products (6 %) and other activities such as wage-earning or formal employment (10 %). The highest diversity of activities was at a peri-urban site, Chuabo Dembe, which differed from all other sites in Cluster and Principal Components Analyses. Fishing dominated activities at four of five sites, with the highest preponderance near the estuary mouth. Women played an important role in generating household income, mainly through farming and operating small businesses in peri-urban areas. The education level declined in rural settings. Overexploitation and degradation of natural ecosystems to provide for an increasing urban population around Quelimane threaten estuarine functioning, making deltaic FBF systems vulnerable. Rural development programmes should focus on improving education levels and the efficiency of food production, processing and distribution systems.

Small-scale LNG projects: Theoretical framework for interaction between stakeholders

Currently, there is a beginning of liquefied natural gas (LNG) market transformation, which is deepening global supply chains through the growth of the number of small-scale projects. The main driver of this transformation was the creation of large-scale LNG hubs, which did not meet expectations for improving the efficiency of gas distribution systems (like in Europe). This has led to an understanding of the need of increasing flexibility and decentralization of gas supply projects, which is almost impossible to implement with traditional large and medium scale facilities. Increasing decentralization leads to a change in the role and composition of stakeholders, and, consequently, determines new algorithms and schemes for their interaction, which are poorly described in the scientific literature. This paper systematizes information about the specifics of such project implementation, defines a list of key stakeholders, their area of responsibility and area of interests. Proposed conceptual model of interaction between stakeholders has shown a significant dependence of small-scale projects on regional economic and infrastructure conditions, as well as on the availability of multiple distributed points of gas consumption.

Determining the probability of accidents on gas distribution and gas consumption pipelines

Introduction. The aim of this study is to analyze the current state of the Russian Federation gas distribution system, based on statistical material on accidents on gas distribution and gas consumption networks. The problem of ensuring reliable operation and safe operation of systems becomes most urgent in large cities and settlements with multi-stage and branched gas distribution networks, since every year the number of gas pipelines, equipment and fittings that have exhausted their design life increases. The objective of the study is to determine the causes and dynamics of accidents, identify the determining factors, develop an algorithm for quantitative assessment of the risk of emergencies and accidents at the facilities of the gas distribution system.
 
 Materials and methods. In the work, proven research methods were used, including analysis and generalization of theory and experience in the field of reliability of gas distribution pipelines, a systematic approach and mathematical modeling were used.
 
 Results. The materials on gasification of the territory of the Russian Federation using the methods of system analysis are generalized and systematized. Mechanisms of development of failures in gas distribution and gas consumption networks are considered, data on accidents are analyzed. The review of existing methods of troubleshooting and methods of assessing the state of gas pipelines, gas fittings and gas-using equipment is carried out. Methods for improving the efficiency, reliability and safety of gas distribution systems are proposed. The main results of the study are to summarize and systematize the materials of gas distribution organizations for the gasification of the territory of the Russian Federation using systems analysis methods.
 
 Conclusions. The results obtained during the analysis on the state of the accident rate of the structural elements of the gas distribution system can be used to monitor the technical condition of the system, including taking preventive measures to prevent accident incidents.

Local Graph Edge Partitioning

Graph edge partitioning, which is essential for the efficiency of distributed graph computation systems, divides a graph into several balanced partitions within a given size to minimize the number of vertices to be cut. Existing graph partitioning models can be classified into two categories: offline and streaming graph partitioning models. The former requires global graph information during the partitioning, which is expensive in terms of time and memory for large-scale graphs. The latter creates partitions based solely on the received graph information. However, the streaming model may result in a lower partitioning quality compared with the offline model. Therefore, this study introduces a Local Graph Edge Partitioning model, which considers only the local information (i.e., a portion of a graph instead of the entire graph) during the partitioning. Considering only the local graph information is meaningful because acquiring complete information for large-scale graphs is expensive. Based on the Local Graph Edge Partitioning model, two local graph edge partitioning algorithms—Two-stage Local Partitioning and Adaptive Local Partitioning—are given. Experimental results obtained on 14 real-world graphs demonstrate that the proposed algorithms outperform rival algorithms in most tested cases. Furthermore, the proposed algorithms are proven to significantly improve the efficiency of the real graph computation system GraphX.

Overview of grounding schemes for solid‐state transformers in distribution networks

Proposed to be the critical enabling component for future distribution networks, solid-state transformers (SSTs) have drawn much attention lately. They have a massive potential to help reduce size and weight, improve efficiency, integrate microgrids, renewables and energy storages in distribution systems, and can fulfil multiple grid functions such as bidirectional power flow control, fault isolation, system reconfiguration, and post-fault restoration. The introduction of these power electronics devices in distribution systems, however, also brings new challenges to the grid. Extra levels of electromagnetic interference, stray current, and personnel safety are among the most prominent practical issues that proper grounding arrangements can address. In this paper, considerations that should be factored into the grounding scheme design for SST ports with different voltage forms and levels are thoroughly reviewed and summarised. The characteristics of various grounding schemes used in AC and DC distribution systems are evaluated and compared in detail from different perspectives. Based on the comprehensive review, several combinations of grounding schemes are recommended for typical SSTs. In addition, the inclusion of new relay protection devices in the SST grounding scheme design, considering their characteristics and unique requirements, to enhance protection and reliability is also discussed.

Power supply capability evaluation of distribution systems with distributed generations under differentiated reliability constraints

With the increasing penetration of distributed generation and diversified reliability requirements of end-users, existing methods for evaluating power supply capability based on the N-1 criterion are no longer applicable. For fully exploiting the impact of differentiated reliability requirements and distributed generation integration on power supply capability, this paper proposes an innovative methodology to evaluate the power supply capability of distribution systems. First, the power supply capability is set as objective function, and the various reliability requirements of users are modelled as the main constraints. Then, an integrated reliability evaluation method is proposed based on the pseudo-sequential Monte Carlo simulation. A tailor-made genetic algorithm is employed to solve the black-box optimization problem. In the case study, a real distribution system is used to validate the proposed methodology. The simulation illustrates that the proposed method can improve the economic efficiency of distribution systems while enhancing the power supply capacity. It is found that the relaxation of reliability constraints can significantly improve power supply capability. In addition, the effect of increasing distributed generation capacity on reliability improvement is more obvious when system load is higher.

A basic mathematical testbed for energy efficiency analyses of DC power distribution systems/microgrids

DC power distribution has become a topic of interest in the recent past, despite being given up a long time. A number of research efforts have been carried out in this field; especially the idea of DC distribution for microgrids has witnessed a significant amount of time and attention. System efficiency is one of the under-research areas of this field that has witnessed a lot of research efforts which were generally simulation based studies. Detailed mathematical efficiency analysis is missing in the present body of knowledge. In this regard, the current research effort aims to present a foundation level mathematical efficiency analysis set-up that may be used as an analytical testbed for different efficiency studies especially those related to the comparative evaluation of DC and AC systems. The current effort highlights the strong dependence of AC and DC distribution system efficiency on the factor of time. The efficiency advantage of DC over AC or vice versa within a specified duration depends on the ratio of DC and AC grid powers summed over the duration.

Multiobjective Multiscenario Framework for RCS Placement in Unbalanced Distribution Systems Considering Uncertainty

This article presents a multiobjective multiscenario framework for the placement of remote-controlled switches (RCSs) to enhance the efficiency and reliability of the unbalanced distribution systems. Two scenarios are formulated, which include healthy and postfault persistent conditions. A healthy condition consists of cumulative power loss and aggregated RCS installation and maintenance costs as objectives. Postfault persistent condition includes the total number of restored load and aggregated RCS installation and maintenance costs as objectives. A set of optimal solutions are derived by employing the nondominated sorting genetic algorithm (NSGA-II) for multiple scenarios. Lastly, a set of optimal solutions are derived by employing a multiscenario integrated NSGA-II (MSNSGA-II) optimization technique utilizing the already obtained optimal solutions. The key contribution of this article is the design of an algorithm, which can deal with both healthy and persistent postfault conditions. The second significant contribution is the consideration of uncertainty in the load and renewable energy sources along with the network reconfiguration. Another vital contribution of this article includes the application of the holomorphic embedding power flow method in an unbalanced distribution system. The effectiveness of the proposed technique is demonstrated by implementing the proposed method on the IEEE 34-bus and IEEE 123-bus system.

Application of the resonant energy separation effect at natural gas reduction points in order to improve the energy efficiency of the gas distribution system

Maintaining the gas temperature and the formation of gas hydrates is one of the main problems in the operation of gas pipelines. Development and implementation of new effective methods for heating the gas during gas reduction will reduce the cost of gas transportation, solve the problem of resource and energy saving in the fuel industry. Study is aimed at increasing the energy efficiency of the natural gas reduction process by using a resonant gas heater to maintain the set temperature at the outlet of the gas distribution station (GDS) and prevent possible hydrate formation and icing of the station equipment. Paper considers the implementation of fireless heating of natural gas and fuel gas savings of heaters due to the introduction of a thermoacoustic reducer, operating on the basis of the Hartmann – Sprenger resonance effect, into the scheme of the reduction unit. By analyzing the existing methods of energy separation and numerical modeling, the effectiveness of the resonant-type energy separation device is substantiated. Modification of the reduction unit by introducing energy separating devices into it will allow general or partial heating of natural gas by its own pressure energy. Developed technology will allow partial (in the future, complete) replacement of heat energy generation at a gas distribution station by burning natural gas.

Theoretical Estimation of Energy Balance Components in Water Networks for Top-Down Approach

The energy balance calculation for pressurized water networks is an important step in assessing the energy efficiency of water distribution systems. However, the calculation generally requires mathematical modelling of the water networks to estimate three important energy components: outgoing energy through water loss (El), friction energy loss (Ef) and energy associated with water loss (EWL). Based on a theoretical energy balance analysis of simplified pipe networks, a simple method is proposed to estimate El, Ef and EWL with minimum data requirements: input energy, water loss (WL) and head loss between the source and the minimum energy point (ΔH). By inclusion of the head loss in water networks into the estimation, the percentages of El and EWL are lower and higher, respectively, than using only the percentage of WL. The percentage of Ef can be a function of the percentage of ΔH. By demonstrating our analysis with the simulation results from the mathematical models of 20 real water networks, the proposed method can be used to effectively estimate El, Ef and EWL as a top-down energy balance approach.

Statistical data of the study of the efficiency of gas distribution systems functioning

The article notes that the organized supply and distribution of gas fuel for the needs of agricultural enterprises, as well as the population, is of great importance. The conclusion is made about the necessity of mandatory energy inspection of gas transportation through pipelines.

Research on evaluation of port railway collection and transportation system

Ports play an essential role in economic and trade, which is an important node and hub in cargo transportation. The important evaluation index of port competitiveness is the efficiency of port collection and distribution system. This paper analyzes the development trend of port collection and distribution system. According to the principle of establishing evaluation index, a reasonable evaluation index system of port collection and transportation system is constructed. The port collection and distribution system as a whole. The index system of port transportation capacity, service level, coordination ability with port and external conditions are constructed. Finally, the paper analyzes the operation process of collection and distribution system of Port A

The role of digital marketing in improving the efficiency of the product distribution system of agricultural enterprises in the Krasnoyarsk Region

The article considers the system of product distribution and the possibilities of its development and improvement through the use of progressive, digital marketing technologies on the example of agricultural enterprises in the Krasnoyarsk Region in Russia. This problem becomes particularly relevant in times of crisis, when the need to reduce the cost of production increases. The process of product distribution is quite expensive, it has a number of organizational disadvantages. This process does not fully use modern digital marketing technologies to form a customer base, which would significantly speed up the process of product distribution. The article identifies the factors that restrain the development of the process of product distribution, which include: long distances between the subjects of the process, insufficient development of the transport network, its slow renewal, lack of distribution centers and their weak technical equipment, insufficiently developed infrastructure. Also, for a more effective organization of product distribution channels, it is necessary to actively implement modern digital marketing technologies in the process of product distribution, which will help to form a customer base and develop long-term communications with potential customers.

Multi-microgrid Energy Management Systems: Architecture, Communication, and Scheduling Strategies

The increasing penetration of various distributed and renewable energy resources at the consumption premises, along with the advanced metering, control and communication technologies, promotes a transition on the structure of traditional distribution systems towards cyber-physical multi-microgrids (MMGs). The networked MMG system is an interconnected cluster of distributed generators, energy storage as well as controllable loads in a distribution system. And its operation complexity can be decomposed to decrease the burdens of communication and control with a decentralized framework. Consequently, the multi-microgrid energy management system (MMGEMS) plays a significant role in improving energy efficiency, power quality and reliability of distribution systems, especially in enhancing system resiliency during contingencies. A comprehensive overview on typical functionalities and architectures of MMGEMS is illustrated. Then, the emerging communication technologies for information monitoring and interaction among MMG clusters are surveyed. Furthermore, various energy scheduling and control strategies of MMGs for interactive energy trading, multi-energy management, and resilient operations are thoroughly analyzed and investigated. Lastly, some challenges with great importance in the future research are presented.

A Novel Hybrid Technique of Frequency Control for Distributed Energy Resources

The rapid increase in the population and fastest development in the industrial sector has increased the energy demand throughout the world. Frequent outages and load shedding has seriously deteriorated the efficiency of the electrical power distribution system. Under such circumstances, the implementation of Distributed Generation (DG) is increasing. Small hydel generators are considered as the most-clean and economical for generating electrical energy. These are very complex nonlinear generators which usually exhibits low frequency electromechanical oscillations due to insufficient damping caused by severe operating conditions. These DGs are not connected to the utility in many cases because, under varying load, they cannot maintain the frequency to the permissible value. This work presents detailed analysis of operating characteristics and proposes a hybrid frequency control strategy of the small hydel systems. The simulation and testing is performed in MATLAB, the results verified the improved performance with the recommended method. The proposed method conserves half of the power consumption. The control scheme regulates the dump load by connecting and disconnecting it affectively. The application of presented methodology is convenient in the deregulated environment, especially under the severe shortage of energy. The proposed model keeps the frequency of system at desired level. It reduces the noise, thereby improving the response time of the designed controller as compared to conventional controllers. The innovative scheme also provides power for small scale industrial, agricultural and other domestic application of far-off areas where the supply of utility main grid is difficult to provide. The recommended scheme is environmental friendly and easy to implement wherever small hydel resources are available.