Influence of single and multiple dry bands on critical flashover voltage of silicone rubber outdoor insulators: simulation and experimental study

Dry band formation on the surface of outdoor insulators is one of the main reasons leading to flashover and power outages. In this paper, a dynamic arc model is proposed for single and multiple dry bands configuration to predict the critical flashover voltage for silicone rubber outdoor insulators. An arc is modelled as a time dependent impedance consisting of a Resistor Inductor Capacitor (RLC) circuit. The effect of dry band location and existence of multiple dry bands on critical flashover voltage is investigated. To validate the proposed model, experiments were conducted in a climate chamber under controlled environmental conditions on rectangular silicone rubber sheets polluted using improved solid layer method based on IEC 60,507. Tests were conducted at different dry band configurations and pollution severity levels. A good correlation was found between experimental results and simulation results. This model can provide a good foundation for the development of mathematical models for station post insulators having multiple dry and clean bands and can be used in the design and selection of outdoor insulators for polluted conditions

ERBM-SE: Extended Restricted Boltzmann Machine for Multi-Objective Single-Channel Speech Enhancement

Machine learning-based supervised single-channel speech enhancement has achieved considerable research interest over conventional approaches. In this paper, an extended Restricted Boltzmann Machine (RBM) is proposed for the spectral masking-based noisy speech enhancement. In conventional RBM, the acoustic features for the speech enhancement task are layerwise extracted and the feature compression may result in loss of vital information during the network training. In order to exploit the important information in the raw data, an extended RBM is proposed for the acoustic feature representation and speech enhancement. In the proposed RBM, the acoustic features are progressively extracted by multiple-stacked RBMs during the pre-training phase. The hidden acoustic features from the previous RBM are combined with the raw input data that serve as the new inputs to the present RBM. By adding the raw data to RBMs, the layer-wise features related to the raw data are progressively extracted, that is helpful to mine valuable information in the raw data. The results using the TIMIT database showed that the proposed method successfully attenuated the noise and gained improvements in the speech quality and intelligibility. The STOI, PESQ and SDR are improved by 16.86%, 25.01% and 3.84dB over the unprocessed noisy speech

Protocol of a scoping review of outcome domains in dermatology

Introduction: Core outcome sets (COSs) are agreed outcomes (domains (subdomains) and instruments) that should be measured as a minimum in clinical trials or practice in certain diseases or clinical fields. Worldwide, the number of COSs is increasing and there might be conceptual overlaps of domains (subdomains) and instruments within disciplines. The aim of this scoping review is to map and to classify all outcomes identified with COS projects relating to skin diseases. Methods and analysis: We will conduct a scoping review of outcomes of skin disease-related COS initiatives to identify all concepts and their definitions. We will search PubMed, Embase and Cochrane library. The search dates will be 1 January 2010 (the point at which Core Outcome Measures in Effectiveness Trials (COMET) was established) to 1 January 2024. We will also review the COMET database and C3 website to identify parts of COSs (domains and/or instruments) that are being developed and published. This review will be supplemented by querying relevant stakeholders from COS organisations, dermatology organisations and patient organisations for additional COSs that were developed. The resulting long lists of outcomes will then be mapped into conceptually similar concepts. Ethics and dissemination: This study was supported by departmental research funds from the Department of Dermatology at Northwestern University. An ethics committee review was waived since this protocol was done by staff researchers with no involvement of patient care. Conflicts of interests, if any, will be addressed by replacing participants with relevant conflicts or reassigning them. The results will be disseminated through publication in peer-reviewed journals, social media posts and promotion by COS organisations

Effect of Neutral Grounding Protection Methods for Compensated Wind/PV Grid-Connected Hybrid Power Systems

The effects of the wind/PV grid-connected system (GCS) can be categorized as technical, environmental, and economic impacts. It has a vital impact for improving the voltage in the power systems; however, it has some negative effects such as interfacing and fault clearing. This paper discusses different grounding methods for fault protection of High-voltage (HV) power systems. Influences of these grounding methods for various fault characteristics on wind/PV GCSs are discussed. Simulation models are implemented in the Alternative Transient Program (ATP) version of the Electromagnetic Transient Program (EMTP). The models allow for different fault factors and grounding methods. Results are obtained to evaluate the impact of each grounding method on the 3-phase short-circuit fault (SCF), double-line-to-ground (DLG) fault, and single-line-to-ground (SLG) fault features. Solid, resistance, and Petersen coil grounding are compared for different faults on wind/PV GCSs. Transient overcurrent and overvoltage waveforms are used to describe the fault case. This paper is intended as a guide to engineers in selecting adequate grounding and ground fault protection schemes for HV, for evaluating existing wind/PV GCSs to minimize the damage of the system components from faults. This research presents the contribution of wind/PV generators and their comparison with the conventional system alone

Reconfiguration and Analysis of PV Array based on Particle Swarm Optimization of Solar Plant

The major shortcoming in the extraction of electrical energy occurs due to partial shading over a limited area of vast spread solar panels underpinning reduction of efficiency. A number of panels are interconnected in series and parallel to form a photovoltaic (PV) array for large power plants and a shadow over a single cell deteriorates overall performance. As a consequence, several peaks are added to the P-V curve causing hotspots in PV panels, degradation of the PV system, and collapse of tracking algorithms. In order to minimize such issues in PV panels, an effective optimization technique is developed by reconfiguring the panels which are capable of reaching the full global power point in a PV system under partial shading conditions. The study proposes particle swarm optimization (PSO) using PV characteristics of Quaid-e-Azam Solar Plant (QASP) in Punjab, Pakistan1. In PSO, electrical connections of PV modules are changed keeping their physical locations unaltered aiming to improve the performance of the PV system. After reconfiguration, the algorithm finds the best combination of PV modules by equalizing the row currents followed by the comparison of row current, voltages, and power of panels. The proposed PSO is proved to be an efficient method for reconfiguring PV modules in very less computational time by increasing the output power of shaded modules

Modelling and Simulation of SCADA and PLC System for Power System Protection Laboratory

The protection of power system is an essential trait in a huge network to efficiently detect and isolate the sections undergoing faults or abnormal behaviour. The key components of a protection scheme include circuit breakers, relays, switchgears and fuses which employ communication from one station to another to achieve high-speed tripping. The automation of these components at the laboratory level using programmable logic controller (PLC) along with supervisory control and data acquisition (SCADA) system owns paramount importance for intelligent decision making, sensing, actuating, monitoring and maintaining the record in the host server. This paper discusses such a technique for conventional power system protection laboratory at a new level of development to promote a control system through PLC and SCADA. The control system has indication of over and under values of voltage, load and frequency, which can trigger malfunctioning of equipment and must be rectified. Furthermore, ground fault and inverse current indication are added to the system for monitoring and controlling purposes. The proposed system enhances the efficiency and safety of the expensive equipment and the personnel to the next level and also introduces new standards of automated protection schemes for modern technical institutes

Modeling and Simulation of SCADA and PLC System for Power System Protection Laboratory

The protection of power system is an essential attribute in a huge network to efficiently detect and isolate the sections undergoing faults or abnormal behavior. The key components of a protection scheme include circuit breakers, relays, switchgears and fuses which employ communication from one station to another to achieve high speed tripping. The automation of these components at loboratory level using programmable logic controller (PLC) along with supervisory control and data acquisition (SCADA) system owns paramount importance for intelligent decision making, sensing, actuating, monitoring and maintaining the record in the host server. This paper discusses such a technique for conventional power system protection laboratory at a new level of development to promote control system through PLC and SCADA. The control system comprises of indication of over and under values of voltage, load and frequency which can trigger malfunctioning of equipment and must be rectified. Furthermore, ground fault and inverse current indication are also added to the system for monitoring and controlling purposes. The proposed system enhances the efficiency, safety of the expensive equipment and the personnel to the next level and also introduces new standards of automated protection schemes for modern technical institutes

Economic Dispatch with Transmission Losses in a Distributed Generation Network of Bahawalpur

In an electrical power system, the ultimate aim is to generate and deliver electrical energy to consumer side with minimum cost involved. As there are a number of ways to generate electrical power such as wind, solar, thermal etc. and different fuel costs and incremental fuel costs associated with them. So, least fuel cost, effective unit commitment, least transmission losses involvement are desirous to achieve economic dispatch in a distributed generation network. In this research, we are committed to do study of economic load dispatch with transmission losses consideration in a distributed generation network of Bahawalpur since earlier, there is no consideration of economic load dispatch in Bahawalpur. As different fuel cost, incremental fuel cost and transmission losses involve with each power station, designing an algorithm considering all these factors and then giving optimal combination is the ultimate solution to achieve economic load dispatch of Bahawalpur district. A MATLAB algorithm is designed in this research paper which gives optimum division of power between two thermal power plants with consideration of transmission losses as well. The two power plants considered here are thermal power plant Muzafargarh and Kot Addu Power Company (KAPCO), the former being located at smaller distance from Bahawalpur district. Then, at the end, load trend of Bahawalpur district, optimum generation verses power demand, associated transmission losses, penalty factor for each generation level and fuel cost economy using the algorithm is shown in results section through graphs and tables. It is concluded that thermal power plant shares higher contribution of load power due to smaller distance from load and thus smaller transmission losses ensuring minimum cost operation

Economic Dispatch with Transmission Losses in a Distributed Generation Network of Bahawalpur

In an electrical power system, the ultimate aim is to generate and deliver electrical energy to consumer side with minimum cost involved. Thus, least fuel cost, effective unit commitment and minimum transmission losses are desirous to achieve economic dispatch in a distributed generation network. In this research, economic dispatch considering transmission losses in a distributed generation network of Bahawalpur is reported. A MATLAB algorithm is designed which gives optimum division of power between two power plants and their transmission losses. Power plants considered here are thermal power plant Muzafargarh and Kot Addu Power Company (KAPCO), the former being located at smaller distance from Bahawalpur district. Finally, load trend of Bahawalpur district, optimum generation verses power demand, associated transmission losses, penalty factor and fuel cost economy are shown in the Results Section through graphs and tables. It is concluded that thermal power plant shares higher contribution of load power due to smaller distance from load and, thus, smaller transmission losses ensuring minimum cost operation

Critical Analysis and Application of Net-Metering Practice in MEPCO

The electrical infrastructure around the globe is expanding at a rapid rate for the sake of fulfilling power demands in the domestic, commercial and entertainment industries aiming to boost the living standards. In this regard, renewable energy sources (RES) are globally accepted potential candidates for maintaining inexhaustible, clean, and reliable electricity with a supplementary feature of economic prospect. The efficiency of power distribution at reduced cost to the consumers can be further enhanced by introducing a two-way billing system so-called net-metering which has the potential to overcome issues such as voltage regulation, power blackouts, overstressed grid and need for expensive storage systems thereby making it beneficial for the grid and the end user. This envisioning has encouraged the Government of Pakistan to install net-metering infrastructure at places which accommodate surplus renewable energy reserves. According to the Electric Power Act 1997, the National Electric Power Regulatory Authority (NEPRA) issued the net-metering rules and regulations in September 2015 by the endorsement of Federal Government which allowed the distribution companies in Pakistan to buy surplus electricity units generated by the consumers in order to partly reimburse the units imported from the utility grid. The aim behind this research work is to promote renewable energy utilization through net-metering mechanism in order to achieve maximum power. The export of units from consumer side to utility grid and vice versa can be made through bidirectional energy meter. In this paper, a solar net-metering analysis has been carried out on ETAP software to determine its benefits in a distribution network. Different scenarios have been investigated, and it is concluded that solar net-metering technique has multiple influential benefits, e.g., improvement in voltage regulation, reduction in transmission and distribution losses, increase in power availability, less billing to consumers, and reduction of loading on utility grid