Conventional Distribution System Research Articles

Implementation of ANFIS-based UPQC for Power Quality and Thermal Management Enhancement in the Distribution System

Conventional distribution systems generally operate with voltage and current waveforms being sinusoidal, though they slightly deviate from the ideal sinusoidal waveform, which is measured as distortion. The increase in power demand has led to the local generation and storage of power (Micro Grid systems). For its adoption, we need to implement smart grid architecture. Power electronics is a technologically sound way to limit different kinds of power quality (PQ) disturbances. It can also be used to control power flow, boost energy transmission capacity, enhance dynamic behavior and voltage stability, and ensure better power quality at distribution within established bounds. Unified Power Quality Conditioners (UPQC), one of the well-known Flexible AC Transmission System (FACTS) devices, are typically used to address problems in distribution systems such as voltage surges, flickers, neutral current reduction, and PQ. Additionally, thermal management is crucial for maintaining system stability and preventing overheating. While dealing with sensitive loads, a UPQC injects harmonics into the system, which can compromise system stability. This article describes an artificial neural network with harmonics elimination techniques for a modified UPQC connected with a Smart Grid. The performance of the proposed system is evaluated using MATLAB/Simulink software.

Short-circuit current analysis of DC distribution system in a ship with non-electric propulsion

Converting conventional AC radial shipboard distribution system to DC system has been recognized as a potential high impact solution to reduce ship’s fuel consumption. As big ships in Indonesia commonly use low voltage AC (LVAC) distribution system an effort to apply low voltage direct current (LVDC) distribution system without replace the propulsion system is a plausible choice. However, technical and economical investigations are required before recommendation to convert the shipboard distribution system to LVDC is officially launched. In this study, technical aspect in the term of short-circuit current is discussed. The goal of this study is to analyze how much the impact on the short-circuit current when LVDC system replaces LVAC system. The impact may affect the feasibility of LVDC system as the short-circuit current in a system dictate the scheme and capacity of the protection devices. Numerical simulations on a sample vessel are performed to obtain the profile of maximum short-circuit currents on all panels. The results show that the utilization of LVDC system decreases the short-circuit current by 10 times. Further investigations on the economic aspect needs to be performed to give clearer view of the feasibility of the LVDC system.

Distribution Network Reconfiguration in Effective Presence of DGs, EVCSs and DRP: A Novel Multi-Objective Approach

By determining the ideal combination of switch on/off status, distribution network reconfiguration (DNR), a critical operational problem in distribution systems, has been employed to increase system efficiency. Additionally, benefits such as improved voltage profiles and loss reduction through reactive power compensation are provided by placing capacitors in the distribution network optimally. Thus, this study formulates multi-objective DNR with optimal allocation of distributed generators (DGs), electric vehicles charging stations (EVCSs) and capacitors. Additionally, the demand response programme (DRP) is employed to enhance the distribution system’s operation performance. Losses and voltage variation, which are significant objectives for conventional distribution systems, are typically the focus of the DNR problem. Modern distribution systems’ security concerns caused by DGs that could jeopardize power system security have been all but ignored in terms of the issue of power system operation. As a result, the primary objective of this study is to address the DNR issue in order to increase reliability. This study specifies the energy not provided (ENS) in order to do this. This work uses a modified shuffled frog leaping algorithm (MSFLA), which benefits from a novel mutation technique, to reduce processing time and improve solution quality, in particular to avoid becoming stuck in local optima. To evaluate the efficiency and adaptability of the suggested method, it is applied to three distribution systems, comprising 33, 69, and 86-node test networks. After that, the outcomes are contrasted with those of various approaches. Power loss and ENS are reduced by around 45% and 5.5%, respectively, by executing the suggested strategy on a 33-node test system compared to the initial value before the DNR.

Microgrid control system architecture for improving energy efficiency and demand response integration

Smart-grids have several advantages over conventional electrical energy distribution systems. On the one hand, they enable smart measuring and control of both, consumption and energy production. On the other hand, they contribute to the integration of renewable energy sources, distributed energy resources and demand response. However, some aspects of smart-grids have not been solved, such as the control of all the components. In this study, some control equipments have been analyzed to establish the control system architecture. As a result of the tests shown in this paper, a suitable design of the control system of a micro-grid is proposed. The power meters, quality analyzers and programmable logic controller to be used in the micro-grid control system have been tested to ensure their suitability for this purpose.

Wavelet-based rapid identification of IGBT switch breakdown in voltage source converter

The power electronic converters have drawn a lot of attention from investigators in recent years. Modern power electronics converters rely heavily on insulated gate bipolar transistors (IGBT). Conventional distribution systems may be made more reliable, stable, and secure by using a microgrid (MG). An acceptable, enticing, and useful option for power distribution networks is inverter-based MGs. This article describes a method for identifying the IGBT switch breakdown failure (IBDF) in a 3-phase, 3-level Voltage Source Converter (VSC) linked to the photovoltaic (PV) grid. The VSC's output phase voltage was subjected to an analysis based on the Discrete Wavelet Transform (DWT) methodology. Kurtosis, skewness, and root-mean-square (RMS) values of the wavelet coefficients of the output phase voltage harmonic spectra of the VSC are all factored in during studies. For the detection of IBDF, comparative learning has been used to identify the specific parameter that is most suitable. Moreover, the comparative analysis and unique contribution of this investigation have been demonstrated.

FOOD HUBS AS TOOL FOR DEVELOPING ENTREPRENEURSHIP IN GASTRONOMY: THE CASE STUDY OF DUBROVNIK

As the planning profession begins to embrace food and agriculture as important opportunities for sustainable cities and towns, planners are searching for ideas that can be implemented at the local level. Food hubs are gaining popularity as a way to build strong local food systems and healthy communities. Food hubs are innovations in local food systems that serve as an alternative to the conventional food distribution system. Hubs help connect small farmers with local markets and increase food access for local residents. But it is clearly that focusing on the local cuisine as a tourist destination product is worthwhile. Food hub operators are skilled business people who have identified a challenge how to satisfy retail and institutional market demand to source from small and middle size producers and have deftly come up with regionally appropriate solutions that not only result in positive economic outcomes but also provide valuable services to producers and their wider community. Food hub operators represent a new kind of food entrepreneur, one that is increasingly demonstrating a financially sound business model that can be both market and mission driven. This paper examines the importance of the establishment of a food hub for the development of entrepreneurship and innovation in gastronomy, i.e. for the development of the gastronomic offer in Dubrovnik. The survey was conducted in June 2022 among 93 graduates of the School of Tourism and Hospitality to find out their opinion about the establishment of a food hub and whether they are inclined to become its users. Research has proven that most graduates would use food hub services and as such they are necessary for business creation and innovation in the food service industry.

Three-stage resilience-oriented active distribution systems operation after natural disasters

Increasing energy demand and the industrialization of communities have been the leading causes of climate change. As a result, natural disasters have increased blackouts in power systems. Climate change mitigation should be a global goal of communities. Since natural disaster occurrence has risen recently, rapid system restoration after natural disasters is essential. Mitigation of global warming is inextricably linked to the mechanisms and architecture of energy systems. Energy resilience is a multi-dimensional solution to this problem. In this research, resilient strategies for dealing with natural disasters have been examined. Implementing distributed energy resources (DERs), smart distribution networks, and defining load priority based on consumers’ preferences have made a viable solution to the post-disaster operation. Previous efforts cared more about the generation and transmission sectors. This study focused on active distribution systems (ADSs) because distribution systems, as a vital part of energy systems, have not sufficiently contributed to crisis management. A framework for resilience enhancement to smartening conventional distribution systems against natural disasters has been proposed. Three-stage socio-technical optimization was investigated, including optimal allocation of battery storage systems (BESSs), intentional islanding, and optimal power flow (OPF) in MATLAB and DIgSILENT. This optimization presents a decision-making tool for distribution system operators to quickly prepare the system against natural disasters. By applying eight scenarios in the proposed system, in the best scenario (CS4), the recovered power value (RPV) has increased from 38% to more than 99% (more than 61% increase in the resilience index). The amount of supplied load increased from 56% to 92%. Furthermore, prioritizing crucial consumers and reconfiguration are two primary crisis management tools. This approach creates a solid ground for avoiding the social consequences of natural disasters like electrocution and power outages of priority consumers. Failure to apply these two techniques would result in a 21% reduction in the RPV.

Diagnostics and Fault Tolerance in DC–DC Converters and Related Industrial Electronics Technologies

The deployment of DC energy systems is an attractive alternative to conventional AC-based energy distribution systems, improving the efficiency of energy supplies and promoting renewable energies [...]

Solar PV-Powered Separately Excited Biogas DC Generator Suitable for Operation in a DC Microgrid

This article aims to manifest a new way of the utilization of renewable resources in a distribution network. Solar power acts as a source of excitation in the field winding of a separately excited biogas DC generator for the generation of DC power. The amount of DC power required by the generator’s field winding is supplied by harnessing a minimum amount of solar energy from a solar photovoltaic (solar PV) for the operation of the bio-power generator of a rated capacity of 5 kW. It is observed, that the availability of 5% peak solar power can be utilized for full excitation of the generator and, it is observed that the full load demand at the time around 16:00 pm can be catered only by the bio-generator. In this work, it has been acknowledged that solar power can be effectively used in low insolation. In addition, it has been revealed, no auxiliary power source is needed for the operation of the generator approximately, 330.22 W of DC power is required by the field winding for full excitation of the DC generator. The present research developed a unique way of power management strategy, which can mitigate the delicate problems in a conventional distribution system.

Conservation Voltage Reduction Strategy for Autonomous Microgrid with Improved Voltage-CurrentDroop-Based Inverter Control Framework

In a conventional AC distribution system, the conservation voltage reduction (CVR) strategy is widely employed to lower down the voltage of specific load to lower the power consumption. The wide applicability of demand side management (DSM) using CVR in a stand-alone microgrid through VSI-based energy sources is a thrust area, that is, not examined yet and needs to be explored. The fast dynamics and flexible control are the characteristics of the voltage-current droop method which further increases the inertia of the voltage source inverter. For utilizing these advantages of this droop method, it is required to determine the accurate droop gain to properly coordinate the distribution of power among DGs. In this paper, the voltage-current droop method is utilized to carry out the function of DSM, and a modified droop computation method for voltage-current droop is formulated to determine the impedance from initial of the DG point to the downstream end for multifeeder network. As most of the droop control techniques emulate the conventional power grid such as Q-V droop control which reduces voltage with the increase of reactive power, the research prospect is very high in devising the new droop computation method for voltage-current droop for accurate control of power. In addition to it, the work is extended to apply the benefits of voltage-current droop to execute DSM strategy in standalone MG. Moreover, the capability of the proposed estimation of droop parameter is implemented on a standalone 5-bus single-feeder multi-DGs network, and furthermore, the scheme is applied to IEEE-9 bus multifeeder multi-DGs network to show the applicability of the proposed scheme. The simulation results produced from MATLAB/Simulink are compared with the decentralized power-based droop method and conventional voltage-current droop technique to analyse the performance of the devised scheme.

Capacity Market for Distribution System Operator – With Reliability Transactions – Considering Critical Loads and Microgrids

Conventional distribution system (DS) asset planning methods consider energy only from transmission systems (TS) and not from distributed energy resources (DER), leading to expensive plans. Newer transactive energy DS (TEDS) asset planning models, built on capacity market mechanisms, consider energy from both TS and DERs, leading to lower-cost plans and maximizing social welfare. However, in both methods the cost of higher reliability requirements for some users are socialized across all users, leading to lower social welfare. In this article, a novel transactive energy capacity market (TECM) model is proposed for DS asset planning. It builds on TEDS incremental capacity auction models by provisioning for critical loads to bid and receive superior reliability as a service. The TECM model considers these reliability transactions, in addition, to selling energy transactions from TS and DERs, buying energy transactions from loads, and asset upgrade transactions from the network operator. The TECM model allows for islanded microgrids and network reconfiguration to maximize social welfare. The TECM model is assessed on several case studies, demonstrating that it achieves higher social welfare and a lower plan cost.

Characteristic Evaluation of Wind Power Distributed Generation Sizing in Distribution System

Energy consumption and environmental issues have become major drivers of increasing renewable energy penetration levels. The electricity generated from renewable energy sources is decentralized throughout distributed generation (DG), which is located at the distribution level. However, the presence of DG can change distribution system characteristics and affect protection systems. Thus, this study aims to investigate the impact of DG in term of its sizing and placement on distribution systems under both normal and fault conditions. In addition, the effects on voltage improvement under normal conditions and current under fault conditions are also considered. The case study system in this study was modelled after an actual section of a 22 kV distribution line from the Provincial Electricity Authority of Thailand using PSCAD software. For DG, wind turbine generation was selected as a renewable energy source. The simulation results demonstrated that the presence of DG has a significant impact on both voltage and current characteristics under both normal and fault conditions. These impacts on the distribution system caused by DG can affect the operation of conventional distribution systems, which require further analysis and preventive measures in order to ensure good system reliability.

Data Analysis Techniques Applied to Distribution Systems: A Systematic Mapping Study

The increasing electricity demand has led the conventional distribution system to evolve into the smart grid context. One of the advantages of this intelligent system is the ability to estimate the states of a grid. Implementing a state estimator in distribution networks requires much analysis – such as the observability of an extensive system, big data techniques for data processing, and the use of artificial intelligence to generate predictions and protect the control system against cyber-attacks. This systematic mapping study covers 15148 articles, selecting 37 for further research and discussion. The reports offer different state estimators and techniques to improve performance, for instance, solutions against malicious data, optimal meter allocation, and voltage control. In addition to these topics, this article discusses different approaches to generate pseudo measurements. Probabilistic and deterministic, machine learning, and neural network models appear as a trend. The studies show the main methods used for data collection, offering a trend toward smart meters.

Combined DC-Link Fed Parallel-VSI-Based DSTATCOM for Power Quality Improvement of a Solar DG Integrated System

In present day power systems, Power Quality (PQ) issues are causing great concern owing to the increased use of power electronic controlled drives and fluctuating and other non-linear loads. This problem is further aggravated by a steady increase in the integration of renewable energy-based Distribution Generation (DG), employing power electronic converters to distribution systems. Custom power devices with suitable control strategies provide an effective solution to these power quality issues. In this work, a typical three-phase distribution system supplying non-linear load and with DG integration is considered. A shunt connected DSTATCOM at PCC of the system is employed to mitigate power quality concerns. Initially, a parallel-VSI based DSTATCOM configuration, employing individual DC-Link and working basically on the principle of current sharing, has been proposed. The analysis is carried out for variable load conditions for PQ enhancement making use of a more effective control theory viz. Instantaneous Real-Reactive Power (IRP) theory for the generation of suitable switching patterns to the individual VSIs of the parallel DSTATCOM. Further, an improvement over the above configuration viz. combined/common DC-Link-fed parallel DSTATCOM is proposed. This configuration has the advantages of minimized sensing elements, reliable operation and low-cost compensation. A similar analysis is carried out for PQ improvement, making use of the same IRP theory with some modifications (known as MIRP theory). The effectiveness of this configuration is established from the simulation results. In all the above cases, the analyses are carried out using MATLAB/Simulink platform and the simulation results are presented in detail. Thus, the proposed parallel VSIs-based DSTATCOM configurations employing suitable control strategies provide effective solutions for power quality issues under varying load conditions in conventional distribution systems.

Optimal Placement and Sizing of Distributed Generation (DG) Units in Electrical Power Distribution Networks

Researchers' attention has recently been on the best ways to integrate Distributed Generation (DG) into the conventional centralized electrical power distribution systems, particularly in the context of the smart grid idea due to its reputation as a viable remedy for the lack of electric power supply. To optimize the environmental, financial, and technological advantages of DG units’ integration for distribution network operators, it is crucial to determine their ideal position and size. The main objective of this study was to develop and simulate an optimization system for the placement and sizing of distributed generation units in electrical power distribution networks for power losses reduction and voltage profile improvement. The specific objectives were to model and develop the load flow algorithm and codes; develop a meta-heuristic optimization algorithm and codes that selects the best location and size of the DG unit; simulate the nested load flow and optimization algorithms and codes on MATLAB and analyze the effectiveness of the developed algorithm via testing on the standard IEEE 33-bus radial electrical power distribution benchmark network. The Backward-Forward Sweep (BFS) technique was employed in the load flow modelling owing to its maximization of the radial structure of distribution systems. The optimization algorithm was developed based on the Multi-objective Particle swamp optimization (PSO) meta-heuristic technique due to its effective global searching characteristic. The line and load data for the IEEE 33-bus test network being a cutting-edge benchmark for contemporary power distribution networks; were obtained from the Power Systems Test Case Archive- a secondary data source. For this network fed by a synchronous generator, the chosen base MVA (Mega Volt Amp) was 10MVA and the base voltage was 12.66kV. The total active and reactive power demand were 3.715MW and 2.3Mvar respectively. The simulation was done on R2021a version of MATLAB/Simulink. The total real and reactive power losses obtained from base case simulation without the placement of any DG unit in the network were obtained as 201.8925kW and 134.6413kvar respectively while the per unit (p.u) average bus voltage was 0.948594 p.u. After the optimal allocation of one, two, three and four DG units, the total real power loss (in kW) in the network reduced by 140.89, 173.89, 189.89 and 195.89 respectively while the total reactive power loss (in kvar) reduced by 86.64, 114.64, 124,64 and 128.64 respectively. Likewise, the per unit average bus voltage improved by 0.0376p. u, 0.0458p.u, 0.0480p.u and 0.0498p.u respectively. Also, the decrease in the total real and reactive power losses and the improvement in bus voltage profiles varies proportionally with the number of DG units optimally placed. In conclusion, the results shows that the total real power loss and the total reactive power loss of the network, were significantly decreased; and the voltage profile of the system was drastically enhanced by incorporating DG units at predetermined buses. The developed algorithm is recommended for application in a real electrical power distribution network for more efficient integration of new distributed generation units in the current electrical power distribution networks.

A Revisit to Recent Developments in the Underfloor Air Distribution Systems

Underfloor air distribution, also known as UFAD, is a technique of providing the space conditioning in offices as well as other public spaces. Because of the substantial benefits which it can provide, it is progressively being regarded as a major alternative to the conventional ceiling-based air distribution systems. This is due to the fact that the UFAD is a technique of providing the space conditioning in the public spaces. This method delivers cooled air directly into the inhabited zone of the building by making advantage of the open space that is created (the underfloor plenum) that exists between the structural concrete slab as well as the underside of a raised access floor system. Air may be supplied through a multiplicity of the supply outlets positioned at the floor level (this is the most typical configuration), or it can be integrated into the structure of the furniture and walls. This paper provides a recent development in the field of HVACs that have employed UFAD systems for improving their effectiveness as well as thermal comfort of humans. UFAD has the potential to assist in the enhancement of a building’s energy efficiency, indoor air quality, occupant comfort, and sustainable practises. The future scope of UFAD is significant, and it has the potential to become a mainstream technology in the building industry.

Deregulated Distribution System Planning - Incremental Capacity Auction Mechanism With Transactive DERs

High penetrations of distributed energy resources (DERs) are driving the transformation of traditional distribution networks into transactive energy distribution systems (TEDS). TEDS depart from conventional distribution system constructs to 1) enable a local distribution operator to maximize social welfare, 2) enable peer-to-peer energy transactions, 3) extract maximum participation and benefits from DERs, 4) usher in competition in the distribution sector to supply electricity via DERs, and 5) hold the potential for a lower asset cost solution, greater customer choice, and higher reliability. The conventional distribution system planning is inadequate for this purpose. Following the new TEDS paradigm, an incremental capacity auction (ICA) is proposed in this paper considering: 1) bids for power capacity from all energy sources (DERs and transmission), 2) bids for network asset upgrades from equipment vendors, and 3) bids from new loads. A holistic auction settlement procedure is developed for the proposed ICA mechanism that can concurrently determine the optimal power capacity to be procured and network asset upgrading, while maximizing social welfare. Further, locational marginal price for power capacity demand is estimated as a by-product of the ICA solution. Benefits are demonstrated via case studies and include increased participation of DERs to supply energy, maximizing the social welfare, and enabling assets deferral considering the available local resources.

Tar cracking enhancement by air sparger installation in the combustion zone of the downdraft gasifier

In the present article, experimental studies are performed on Imbert downdraft gasifier using two different air distribution systems (two-nozzle and air-sparger) for the combustion zone. A novel air distribution system (air-sparger) is designed to supply uniform air across the combustion zone for achieving uniform temperature and enhancing the tar cracking. The effect of operating parameters (Equivalence ratio, temperature, air flow rate, and biomass consumption) on the tar cracking and producer gas compositions are investigated. Tar is measured in the producer gas before and after the gas cleaning units using a stack monitoring system. The experiments are performed by varying the airflow rate between 3 and 7 Nm3 h−1, and the equivalence ratio varies from 0.24 to 0.38. The operating parameters and air-sparger have significantly influenced the zone's temperature, producer gas composition, and the tar content in the producer gas. The maximum temperature of the combustion zone and reduction zone increases from 764 to 975 °C and 467 to 760 °C respectively with the air-sparger compared to the two-nozzle conventional air distribution system at the airflow rate of 7 Nm3 h−1. The lower heating value of the producer gas and the cold gas efficiency of the gasifier increased from 4.28 to 4.37 MJ Nm−3 and 48.55–55.05%, respectively, with the air-sparger. The incorporation of air-sparger reduces tar in producer gas from 23.95 to 0.97 g Nm−3 before gas cleaning unit at the airflow rate of 7 Nm3 h−1. Air-sparger has shown the adequate potential to enhance tar cracking and improve the overall gasifier performance.

Microbial Water Quality through a Full-Scale Advanced Wastewater Treatment Demonstration Facility.

The fates of viruses, bacteria, and antibiotic resistance genes during advanced wastewater treatment are important to assess for implementation of potable reuse systems. Here, a full-scale advanced wastewater treatment demonstration facility (ozone, biological activated carbon filtration, micro/ultrafiltration, reverse osmosis, and advanced oxidation) was sampled over three months. Atypically, no disinfectant residual was applied before the microfiltration step. Microbial cell concentrations and viability were assessed via flow cytometry and adenosine triphosphate (ATP). Concentrations of bacteria (16S rRNA gene), viruses (human adenovirus and JC polyomavirus), and antibiotic resistance genes (sul1 and bla TEM ) were assessed via quantitative PCR following the concentration of large sample volumes by dead-end ultrafiltration. In all membrane filtration permeates, microbial concentrations were higher than previously reported for chloraminated membranes, and log10 reduction values were lower than expected. Concentrations of 16S rRNA and sul1 genes were reduced by treatment but remained quantifiable in reverse osmosis permeate. It is unclear whether sul1 in the RO permeate was from the passage of resistance genes or new growth of microorganisms, but the concentrations were on the low end of those reported for conventional drinking water distribution systems. Adenovirus, JC polyomavirus, and bla TEM genes were reduced below the limit of detection (∼10-2 gene copies per mL) by microfiltration. The results provide insights into how treatment train design and operation choices affect microbial water quality as well as the use of flow cytometry and ATP for online monitoring and process control.

Optimal DG allocation and sizing in distribution systems with Thevenin based impedance stability index

The applications of Distributed Generation (DG) play a significant role to provide the benefit to conventional distribution systems. However, the sizing and location of these DG units should be taken into consideration to get maximum gain and benefit. If DGs are not located and sized properly, the distribution system can be adversely affected. So, optimal allocation and sizing are needed to avoid instability problems and more costs to increase the efficiency and quality of energy in distribution systems. This paper addresses the optimal sizing and allocation of DGs for power losses, voltage profile and stability improvement, introducing a proposed stability index based on Thevenin impedance in a distribution network. The stability index is calculated by the proposed approach based on Thevenin. Thevenin is obtained based on a two-bus system by reduction of more than two bus systems. The optimal sizing and location of DGs are also obtained by operating DGs under different power factors. The reactive capability of DGs is also shown by simulations with DGs operated under different power factors. The problem of optimal sizing and location of DGs, which is a nonlinear optimization problem with discrete and continuous variables, is solved based on the mixed integer Genetic Algorithm (GA). Also, the proposed approach is verified by using Grey Wolf Optimization (GWO) method. The problem contains multi-objectives with three objective functions: system power losses, voltage deviation and the Thevenin based stability index. The proposed approach has been tested on the IEEE-69 and 118-bus test system to demonstrate its effectiveness. The comparison with some other methods shows that the proposed approach gives better results than other methods while reducing the power losses and improving voltage and system stability in all suggested scenarios by finding the optimal placement and sizing of DG units. It is also shown that the reduction in power loss, voltage and stability improvements are increased more by using the reactive power capability of DGs. The results show that optimum located and sized DGs not only decreases the power loss, but also improve the voltage profile and stability of the system.