Reliability improvement and loss reduction in radial distribution system with network reconfiguration algorithms using loss sensitivity factor

<p>Studies on load flow in electrical distribution system have always been an area of interest for research from the previous few years. Various approaches and techniques are brought into light for load flow studies within the system and simulation tools are being used to work out on varied characteristics of system. This study concentrates on these approaches and the improvements made to the already existing techniques considering time and the algorithms complexity. Also, the paper explains the network reconfiguration (NR) techniques considered in reconfiguring radial distribution network (RDN) to reduce power losses in distribution system and delivers an approach to how various network reconfiguration techniques support loss reduction and improvement of reliability in the electrical distribution network.</p>

A Comparative Study of the Electrical and Electromechanical Responses of Carbon Nanotube/Polypropylene Composites in Alternating and Direct Current

The electrical and electromechanical responses of ~200 µm thick extruded nanocomposite films comprising of 4 wt.% and 5 wt.% multiwall carbon nanotubes mixed with polypropylene are investigated under an alternating current (AC) and compared to their direct current (DC) response. The AC electrical response to frequency (f) and strain (piezoimpedance) is characterized using two configurations, namely one that promotes resistive dominance (resistive configuration) and the other that promotes the permittivity/capacitive contribution (dielectric configuration). For the resistive configuration, the frequency response indicated a resistive–capacitive (RC) behavior (negative phase angle, θ), with a significant contribution of capacitance for frequencies of 104 Hz and above, depending on the nanotube content. The piezoimpedance characterization in the resistive configuration yielded an increasing impedance modulus (|Z|) and an increasing (negative) value of θ as the strain increased. The piezoimpedance sensitivity at f = 10 kHz was ~30% higher than the corresponding DC piezoresistive sensitivity, yielding a sensitivity factor of 9.9 for |Z| and a higher sensitivity factor (~12.7) for θ. The dielectric configuration enhanced the permittivity contribution to impedance, but it was the least sensitive to strain.

Creep evaluation and temperature dependence in self-sensing micro carbon polymer-based composites for further development as an Internet of Things Sensor device

This article investigates the dependency of temperature on electrical resistance (R) change in micro carbon fiber polymer composites (MCFPC), for further development as an Internet of Things sensor from previous research works. Three mixtures were prepared using Dow Corning’s Silastic 145 as base polymer and made vary fiber content weight percentages: fiber diameter to length ratio ∅⁄l 0.13 and carbon fiber content of 13%; ∅⁄l:0.66 and carbon fiber contents of 40% and 50%. Composites tested were submitted to temperature loading, with a constant strain of 0.0%, for assessment of R when a change in the composite’s temperature occurs. The composite response was observed to follow an Arrhenius function, for temperatures ranging from −10°C to 40°C. The apparent activation energy was calculated to evaluate further differences between carbon fiber contents and the sensitivity factor, [Formula: see text] due to temperature is determined. The specimens were also tested with a constant strain of 2.86% to assess creep. It was found that creep and R, over the period of time in the analysis, best fit a discrete latent variable model. The sensitivity factor change is determined in regard to stress relaxation, [Formula: see text]. The properties of MCFPC investigated here can be used to establish relationships between electrical resistance outputs and environmental loading conditions for this type of composites, enabling the possibility of deployment as part of a management system network for structural monitoring with real-time data acquisition.

The Study of the Effect of Capacity Increase and Photovoltaic Placement on Power Loss, Voltage Profile by Considering THDv

The application of Photovoltaic (PV) is one solution to the increasing demand for electrical energy. However, the application of photovoltaic (PV) must be in the right location and capacity so that the power loss you want to reduce is large and the voltage profile is good. Photovoltaic (PV) generates DC voltage which is then required by an inverter to convert it to AC. The inverter is a non-linear load that produces harmonics. Harmonics in an electric power system can be known from Total Harmonic Distortion (THD). The purpose of this study is to determine the optimal location of placement (PV) and its maximum capacity so that the power loss is smaller. The resulting voltage and THD profile conform to the permitted standards. The methods used in determining the optimal location of photovoltaic (PV) are Loss Sensitivity Factor (LSF) and Voltage Sensitivity Index (VSI). ETAP 16 software is used for power and harmonic flow simulation. From this research, the most optimal photovoltaic (PV) placement is on bus 10 (bus 283 T) with a maximum capacity of 3255 kVA. This placement location provides minimal power loss and a good voltage profile taking into account the permitted standard THDv.

Investigation of Additively Manufactured PEEK Modified With Glass Microballons as a Function of Density and Volume Fraction

Low density and strong mechanical characteristics make hollow glass microballons (HGM) filled polyehteretherketone (PEEK) composites excellent for aerospace, transportation and civil applications. In this study, PEEK was filled with different densities of HGMs (low, medium, and high) and varied volume fractions (Vf) of HGMs (10%, 15%, and 20%) and exposed to different strain rates to investigate thermal, physical, energy absorption, and other physico-mechanical responses. PEEK/HGMs composites demonstrated a substantial strain rate impact, with the strain rate sensitivity factor increasing as the strain rate increased while decreasing as the filler Vf increased. The density of the composites was also shown to be inversely related to their strength properties. Incorporating high-density HGMs into the PEEK resulted in the lowest composite density so far reported while ensuring mechanical properties. Scanning electron microscopy images revealed that the HGM dispersion is uniform inside the matrix. Thermal stability of the syntactic foam was investigated by using Thermo Gravity Analysis (TGA) under inert atmosphere and oxidative environment conditions. The infusion of microspheres enhances the thermal stability of LDPEs, MDPEs, and HDPEs samples in an inert environment, with HDPEs samples being the most thermally stable. This might lead to the formation of a strong bond between polymer chains and HGM particles.

RISK ASSESSMENT MODEL OF COASTAL SEA POLLUTION BY BLACK (SEWAGE) WATERS FROM VESSELS

Qualitative risk assessment using the risk matrices recommended by International Maritime Organization (IMO) and International Standards Organization (ISO) cannot be used for the risk assessment of the pollution of precisely determined part of the coastal sea by black waters from various vessels. Therefore, an original model has been set for risk assessment by means of multiplicative matrices at three levels, allowing risk assessment for very complex assessments with a lot more input factors unlike the classic risk matrix that has two input factors (frequency of occurrence, intensity of consequences). The proposed model of risk assessment uses matrices which first determine the vessel risk index taking into consideration the factor of device for the processing of black waters and the factor of regulations that are applied to the respective vessels. Later, the location sensitivity index is determined, which takes into consideration the sensitivity factor of the location and the factor of impact on the location. Finally, at the third level the assessed risk of sea pollution by black waters is determined according to the type of vessel at precisely defined maritime zone locations. The offered model of risk assessment using multiplicative matrices has practical application and can be used also for many other risk assessments that take into consideration many input factors that affect the risk. The result of risk assessment of the pollution of the coastal sea can be used in decision-making in risk management for undertaking measures in order to protect the coastal sea, human health, and economic activities of a certain area in the coastal sea.

Investigation on Strain Rate Sensitivity of 3D Printed sPEEK-HAP/rGO Composites

Nanofillers can be added to polymers to improve their mechanical behavior. However, the yield behaviour of most polymer composites is influenced by strain rate. The majority of the research focused on the behaviour of polymer composites at high strain rates. This work aims to investigate how hydroxyapatite (HAP) and reduced Graphene Oxide (rGO) nanofillers affect the mechanical properties of sulphonated polyetheretherketone (sPEEK) at low (tensile and compression behaviour) and high strain rates (compression behaviour). The thermal, mechanical, and energy absorption responses of sPEEK filled with HAP and varying mass fraction (Mf) of rGO (0.5%, 1%, and 1.5%) at different strain are studied in detail. The strong strain rate effect was seen in HAp and rGO loaded sPEEK composites. The strain rate sensitivity factor of sPEEK-HAP/rGO improved as the strain rate increased, but decreased when the Mf of rGO increased. Under low strain rate compression, HAp and rGO loaded sPEEK absorbed more energy at Mf about 4%. SEM micrography was used to study the microstructures of the fractured interfaces of the components, revealing that the HAp and sPEEK materials formed a good compatibility in presence of rGO.

Optimal allocation of Multiple Distributed Generators and Shunt Capacitors in a Distribution System using Political Optimization Algorithm

To meet the increasing real & reactive power demand of a distribution system (DS), it is essential to allocate the Distributed Generators (DGs) and Shunt capacitors (SCs) optimally. In this article, multiple DGs and SCs are allocated simultaneously in the DS aiming minimal power loss (PL), improved voltage stability index (VSI) and voltage profile of the system. A combined approach considering loss sensitivity factor (LSF) and political optimization algorithm (POA) is proposed to solve the allocation and sizing of DGs and SCs. The analysis is performed on an IEEE 33 bus system considering 9 different scenarios and results are compared with other Meta heuristic techniques. The analysis is extended for a 24 hour case study to prove the efficacy of the proposed combined approach. From all the performed simulations it can be observed that the combined approach helps in minimizing power loss and improving voltage profile and VSI for dynamic load variations effectively.

Engineering the sensitivity of macroscopic physical systems to variations in the fine-structure constant

Experiments aimed at searching for variations in the fine-structure constant α are based on spectroscopy of transitions in microscopic bound systems, such as atoms and ions, or resonances in optical cavities. The sensitivities of these systems to variations in α are typically on the order of unity and are fixed for a given system. For heavy atoms, highly charged ions and nuclear transitions, the sensitivity can be increased by benefiting from the relativistic effects and favorable arrangement of quantum states. This article proposes a new method for controlling the sensitivity factor of macroscopic physical systems. Specific concepts of optical cavities with tunable sensitivity to α are described. These systems show qualitatively different properties from those of previous studies of the sensitivity of macroscopic systems to variations in α, in which the sensitivity was found to be fixed and fundamentally limited to an order of unity. Although possible experimental constraints attainable with the specific optical cavity arrangements proposed in this article do not yet exceed the present best constraints on α variations, this work paves the way for developing new approaches to searching for variations in the fundamental constants of physics.

Modified Analytical Approach for PV-DGs Integration into a Radial Distribution Network Considering Loss Sensitivity and Voltage Stability

Achieving the goals of distribution systems operation often involves taking vital decisions with adequate consideration for several but often contradictory technical and economic criteria. Hence, this paper presents a modified analytical approach for optimal location and sizing of solar PV-based DG units into radial distribution network (RDN) considering strategic combination of important power system planning criteria. The considered criteria are total planning cost, active power loss and voltage stability, under credible distribution network operation constraints. The optimal DG placement approach is derived from the modification of the analytical approach for DG placement using line-loss sensitivity factor and the multiobjective constriction factor-based particle swarm optimization is adopted for optimal sizing. The effectiveness of the proposed procedure is tested on the IEEE 33-bus system modeled using Matlab considering three scenarios. The results are compared with existing reports presented in the literature and the results obtained from the proposed approach shows credible improvement in the RDN steady-state operation performance for line-loss reduction, voltage profile improvement and voltage stability improvement.