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Liu, Yunxin, Liangzhong Yao, Siyang Liao, Jian Xu, Di Wu, Wei Tang i Cheng Yang. "The Voltage Regulation Control Strategy with Distributed Photovoltaic Participation under Serious Failure Based on Transient Voltage Margin". E3S Web of Conferences 186 (2020): 01002. http://dx.doi.org/10.1051/e3sconf/202018601002.
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With the poor ability of distributed PV to withstand voltage fluctuation, the voltage fluctuation caused by DC blocking can lead to large-scale disorderly de-networking of distributed PV, especially those distributed PV which close to voltage weak buses. which means that more and more attentions are paid to the transient voltage stability (TVS). If distributed PV can participation in reactive compensation, we don’t need to add additional reactive power compensator, voltage stability of voltage weak buses will be increased, which can reduce PV off-grid. Therefore, for the HVDC receiving end system under distributed PV intensive access, first of all, we need to find the voltage weak bus, then increase the reactive power output of distributed PV near the voltage weak buses to increase transient voltage margin. Taking the simplified model of power system in Anhui Province as an example, the validity of the strategy is verified, and the results show that the transient voltage stability of the system has been improved.
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Verayiah, Renuga, Azah Mohamed i Syahirah Abd Halim. "Reactive Power Tracing Index LQP_LT for Voltage Unstable Load Bus Identification in Power Systems". Indonesian Journal of Electrical Engineering and Computer Science 12, nr 3 (1.12.2018): 889. http://dx.doi.org/10.11591/ijeecs.v12.i3.pp889-898.
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Existing power systems are significantly susceptible to voltage instability problem since such systems are stressed with the huge power transfers across the grids. To guarantee power system stability during stressed conditions, it is important to first identify the voltage unstable load buses to determine appropriate locations for under voltage load shedding. In this study, a new method is proposed for determining weak load bus locations by using reactive power tracing to develop a novel reactive power tracing capable index, named as LQP_LT. The reactive power tracing algorithm is integrated with the LQP_LT index formulation to generate priority ranking list of weak load buses. The LQP_LT index was tested on the 57 bus system and the resulting priority ranking list is found to have successfully determined the weak load buses for load shedding in the test system. Comparison with other stability indices revealed that the LQP_LT has better sensitivity and response towards determining the location of the weakest load bus for under voltage load shedding implementation.
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Amusan, Olumuyiwa T., Nnamdi I. Nwulu i Saheed Lekan Gbadamosi. "Identification of Weak Buses for Optimal Load Shedding Using Differential Evolution". Sustainability 14, nr 6 (8.03.2022): 3146. http://dx.doi.org/10.3390/su14063146.
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For the sustainability of power supply and operation systems, planners aim to deliver power at an optimum value to consumers, while maintaining stability in the system. The load-shedding approach has proven to be an effective means of achieving the desired stability. This paper presents a nodal analysis to establish critical bus identification in the power grid. A power simulation for load shedding was created using the power system analysis toolbox (PSAT) for identifying and isolating weak buses on the power system. A computational algorithm was developed using differential evolution (DE) for minimizing service interruptions and blackouts, and was tested against the conventional genetic algorithm (GA). The proposed algorithm was implemented on an IEEE 30-bus test system. The simulation results were analyzed before and after the application of DE. It was observed that after the application of DE, load shedding gives an efficient result of 10.6%, 8.7%, and 13.4% improvement at buses 26, 29, and 30, respectively, after being tested using a genetic algorithm (GA), with a result of 10.2%, 7.6% and 13.1% on the same respective buses. This work will further expand the reliability and availability of power systems toward a sustainable, steady power supply that is void of nodal or bus cutoffs.
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Song, Y. H., H. B. Wan i A. T. Johns. "Kohonen neural network based approach to voltage weak buses/areas identification". IEE Proceedings - Generation, Transmission and Distribution 144, nr 3 (1997): 340. http://dx.doi.org/10.1049/ip-gtd:19970913.
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Li, Jia Long, i Wei Wei. "Study on Voltage Stability Weak Buses of Power System with Multiple Power Sources Integrated". Applied Mechanics and Materials 391 (wrzesień 2013): 281–86. http://dx.doi.org/10.4028/www.scientific.net/amm.391.281.
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To obtain the distribution of voltage stability weak buses (VSWB) for power system with multiple power sources integrated, so as to provide a basis for voltage stability control, an analysis method under full time frame is proposed in this paper. Based on the modeling of multiple power sources, combined with the load prediction, the active power output prediction of wind and photovoltaic power and the generation scheduling of conventional power, considering different patterns of load increase and power output increase and allocation of multiple power sources, within a certain period of time and for the specifically selected time sections, the continuation power flow method is respectively used to get the voltage stability critical point (SNB point), where modal analysis is applied, so that the VSWB are obtained of the certain time section. The same calculation is carried out for all the time sections selected, and then the distribution and occurrence frequency of VSWB are summed up, thereby acquiring the concrete condition of VSWB within such certain time period. Its considered that the condition of VSWB can be affected by the different integration buses and penetration rates of multiple power sources. The proposed method is verified on the IEEE 118-bus system, as well as the fact with practical significance that the condition of VSWB varies with the difference of integration buses and the penetration rates of multiple power sources.
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Verayiah, Renuga, i Azah Mohamed. "Comparison of Weak Load Bus Detection using LQP_LT Index with PV and QV Analysis of PSS/E". Indonesian Journal of Electrical Engineering and Computer Science 12, nr 2 (1.11.2018): 577. http://dx.doi.org/10.11591/ijeecs.v12.i2.pp577-584.
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Identification of weak load buses which contributes to voltage instability problem is crucial in order for an appropriate mitigation action to be executed. The current power system transmission is not only stressed to deliver high load demand at the receiving end but also facing new challenges brought by the penetratrion of renewable energy sources. This new scenario requires power system operation and analysis to be robust and fast in detecting the accurate weak load bus for correction action. Due to this, many online indices to detect weak load bus during power system contingency have been developed. Nevertheless, LQP_LT is of the latest index developed which ultimately has the reactive power tracing capability for weak load bus detection and generate priority ranking list of the weak load buses. This index was tested on IEEE 14 bus test system for different contingency scenarios. The results obtained from the LQP_LT index is compared and validated with the PV and QV analyses obtained using industrial graded PSS/E software. It was concluded that the LQP_LT index is found to be robust, efficient and need less computation time as compared to the execution of voltage stability analysis using the PSS/E Tool.
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Dandotia, Ashish, Mukesh Kumar Gupta, Malay Kumar Banerjee, Suraj Kumar Singh, Bojan Đurin, Dragana Dogančić i Nikola Kranjčić. "Optimal Placement and Size of SVC with Cost-Effective Function Using Genetic Algorithm for Voltage Profile Improvement in Renewable Integrated Power Systems". Energies 16, nr 6 (10.03.2023): 2637. http://dx.doi.org/10.3390/en16062637.
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Given the concern for maintaining voltage stability in power systems integrated with renewable power systems due to a mismatch in generation and demand, there remains a need to invoke flexible alternating current transmission system (FACTS) devices in the distribution network. The present paper deals with identifying the locations of placement of a static var compensator in an experimental IEEE 14-bus system; the voltage drop in different buses in an IEEE 14-bus system is calculated by the standard formula. The total voltage drop in the network (TVDN) is also calculated as a reference. The ranking of buses in order of decreasing voltage drop is made, and the weak buses are identified as those showing the maximum or near-maximum voltage drop for the installation of a Static Var Compensator (SVC). The optimum usable size is calculated using a Genetic Algorithm approach to optimize the installation cost. After size optimization, installing a 2 MW solar generator is considered for the weak and most potential bus, which suffers from voltage drops or power loss. Based on the generator at the weakest bus, the total power loss in the network is calculated and compared with a similar method to assess the efficiency of the proposed model. Thus, the voltage stability enhancement problem is solved by applying a Genetic algorithm (GA) to optimize SVC size and using the Total Voltage Drop in Network (TVDN) method to identify weak buses in the systems. It is found that the performance of the proposed system is comparable with another existing system. It is further observed that a gain in power loss to 6.56% is achievable by adopting the proposed strategy, and the gain is better than the other system.
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Mogaka, Ombuki, Roy Orenge i Julius Ndirangu. "Static Voltage Stability Assessment of the Kenyan Power Network". Journal of Electrical and Computer Engineering 2021 (24.02.2021): 1–16. http://dx.doi.org/10.1155/2021/5079607.
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In recent years, the Kenyan Power Network has witnessed large growths in load demand. Although the increased load demand has somewhat been matched with an increase in transmission and generation capacity, the rate of expansion has not been matched with the rate of increase in load demand due to economic, environmental, and geographical constraints. This has led to the system being prone to instability since it is being operated under stressed conditions. In the recent past, several studies have been carried out on voltage stability analysis and improvement using various conventional methods. However, conventional methods have various limitations in their utilization for voltage stability analysis. One solution to overcome these limitations is to employ a combination of one or more methods so as to get more information and greater degree of accuracy in voltage stability studies. In this paper, a methodology is proposed involving the combination of QV modal analysis, sensitivity analysis (VQ) and power-voltage curves in assessing the static voltage stability analysis taking a case study of the Kenyan Power Network. V-Q sensitivity analysis and QV modal analysis have been used to identify the load regions most susceptible to voltage instability and the corresponding weak buses in the network for various V-Q responses. Reactive power loss sensitivities for branches in the network have been used to determine the critical (weak) lines in the network. Loading margins (LM) and voltage stability margins (VSM) have then been used to determine the proximity to voltage collapse of the voltage weak buses identified by QV modal analysis. The effect of tripping one the critical lines on the voltage weak buses is also investigated. The current high voltage power network under the average peak loading conditions during the year 2019 is considered for the study. The paper also reviews existing voltage stability analysis methods and their limitations.
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Hlaing, Ya Min Su, i Ze Ya Aung. "Performance Analysis on Transmission Line for Improvement of Load Flow". Advanced Materials Research 433-440 (styczeń 2012): 7208–12. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.7208.
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This thesis implements power flow application, Newton-Raphson method. The Newton-Raphson method is mainly employed in the solution of power flow problems. The network of Myanma electric power system is used as the reference case. The system network contains 90 buses and 106 brunches. The weak points are found in the network by using Newton-Raphson method. Bus 16, 17, 85 and 86 have the most weak bus voltages. The medium transmission line between bus 87 and bus 17 is compensated by using MATLAB program software. The transmission line is compensated with shunt reactors, series and shunt capacitors to improve transient and steady-state stability, more economical loading, and minimum voltage dip on load buses and to supply the requisite reactive power to maintain the receiving end voltage at a satisfactory level. The system performance is tested under steady-state condition. This paper investigates and improves the steady–state operation of Myanma Power System Network.
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Acharjee, P. "Identification of maximum loadability limit and weak buses using security constraint genetic algorithm". International Journal of Electrical Power & Energy Systems 36, nr 1 (marzec 2012): 40–50. http://dx.doi.org/10.1016/j.ijepes.2011.10.021.
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Acharjee, P., S. Mallick, S. S. Thakur i S. P. Ghoshal. "Detection of maximum loadability limits and weak buses using Chaotic PSO considering security constraints". Chaos, Solitons & Fractals 44, nr 8 (sierpień 2011): 600–612. http://dx.doi.org/10.1016/j.chaos.2011.05.008.
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Amin, Dara Hama. "Enhancement of Voltage Stability by Using SVC for 30-Bus Power System". Kurdistan Journal of Applied Research 4, nr 2 (28.11.2019): 128–36. http://dx.doi.org/10.24017/science.2019.2.14.
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Voltage stability refers to maintaining the value of the voltage in all busses of the electric network at a steady level (initial operating point) during any sudden disturbance. Voltage instability may happen due to an increase in the demand of the load or in case of any change in the reactive power, thus, the system will go into uncontrollable and unstoppable decline in the voltage level. The effect of Static Var Compensator (SVC) on voltage stability is discussed in the paper, as well as the improvement of the voltage profile. Usually, SVC and FACTS devices were used for enhancing the voltage level profile and so the stability. Choosing the optimal location for the FACTS devices is essential due to its expensive costs. This paper used sensitivity factor to helpful to determine the most correct placement of FACTS devices in the system. Simulations are performed on Kurdistan Region 30-bus Power System using MATLAB-PSAT tool. As a result, the voltage of all 30 buses calculated. Based on the “voltage sensitivity factor”, the nominated weak buses has been marked which are suitable for placing the FACTS devices in order to improve the limits of the voltage stability of the system. Moreover, depending on the obtained optimal locations, a full analysis of the voltage and powers for the system has applied in two cases, before and after placing SVC respectively which is result in notable stability improvement and losses reduction.
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Al Mamari, Adnan Saif, Siti Fauziah Toha, Salmiah Ahmad i Ali Salim Al Mamari. "A modal analysis based on reactive power compensation on 6-bus Oman electrical grid". International Journal of Power Electronics and Drive Systems (IJPEDS) 12, nr 2 (1.06.2021): 757. http://dx.doi.org/10.11591/ijpeds.v12.i2.pp757-764.
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This paper covers the modal analysis application (MATLAB 2019a) for improving the voltage profiles by optimum positioning of the capacitor banks for 6-bus Oman Electrical System because the Oman electricity TransmissionCompany (OETC) is suffering of drop voltage in these 6 buses especially during summer season as a peak period. The Newton-Raphson (N-R) method will help to determine the required reactive power for each load bus and as well the ideal position or point of capacitors. The process aims to maintain the Q-V relations of the electrical grid by correlating the lowest Eigen-values to related Eigen-vectors in obtained Jacobian matrix. It depends on the Eigen-values, if they are positive then the system’s voltage is stable otherwise it is not stable. In a stable system, the potential voltage collapse could be anticipated by checking the participation factors for a group of minimal positive Eigen-values. In general, the critical weak bus is associated with lowerEigen-values. Electrical system collapse is attributable to the weakest bus in the network and it could be avoided by determining the weak buses and providing capacitor banks at suitable locations which will lead to improve the voltage stability margin.
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Uzor, J. C., D. C. Oyiogu i C. O. Ikaraoha. "Reduction of Active and Reactive Power Losses on Transmission Lines using SSSC". International Journal of Research and Innovation in Applied Science VIII, nr IV (2023): 92–108. http://dx.doi.org/10.51584/ijrias.2023.8412.
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This paper discusses a comprehensive study on reduction of power (active and reactive) losses in transmission lines using a second generation FACTS device, Static Synchronons Series Compensator (SSSC). Modern restructured power systems sometimes operate with heavily loaded lines resulting in power losses and higher voltage deviations, which may lead to mal-operation of power system and eventual collapse of the system. This is mainly due to continuous and uncertain growth in demand for electrical power. The paper presents a methodology to solve the problem of power losses in the Nigerian 28 – bus power system by incorporating Static Synchronons Series Compensator in the network using Newton-Rahson power flow algorithm. Simulation of power flow solution without and with the FACTS device was done using a Matlab software. The results showed that the maximum power (active and reactive) loss in the system without SSSC occurred in the transmission line connecting bus 17 (Jebba) to bus 23(Shiroro) and a 19.32% loss reduction was obtained on the line after the incorporation of the SSSC FACTS device giving a power saving of 80.68%. The total system active and reactive power losses before the application of SSSC was 205.183MW and 1594.683MVAR respectively. However, when the FACTS device was applied at the weak buses the total system active and reactive power losses reduced to 144.571MW and 1136.863MVAR respectively giving a percentage loss reduction in active and reactive power of 29.54% and 28.71% respectively resulting in a power saving of 70.46% and 71.29%. Hence, more power was available in the network when compared to the base case due to the installation of SSSC. Also an improvement in the voltage magnitude at the weak buses and other buses were noticed as they were all maintained at 1.0 PU.
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Serem, Noah, Lawrence K. Letting i Josiah Munda. "Voltage Profile and Sensitivity Analysis for a Grid Connected Solar, Wind and Small Hydro Hybrid System". Energies 14, nr 12 (15.06.2021): 3555. http://dx.doi.org/10.3390/en14123555.
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Due to increase in integration of renewable energy into the grid and power quality issues arising from it, there is need for analysis and power improvement of such networks. This paper presents voltage profile, Q-V sensitivity analysis and Q-V curves analysis for a grid that is highly penetrated by renewable energy sources; solar PV, wind power and small hydro systems. Analysis is done on IEEE 39 bus test system with Wind power injection alone, PV power injection alone, with PV and wind power injection and with PV, wind and micro hydro power injection to the grid. The analysis is used to determine the buses where voltage stability improvement is needed. From the results, it was concluded that injection of the modeled wind power alone helped in stabilizing the voltage levels as determined from voltage profiles and reactive power margins. Replacing some of the conventional sources with PV power led to reduction of voltages for weak buses below the required standards. Injection of power from more than one renewable energy source helped in slightly improving the voltage levels. Distribution Static compensators (D-STATCOMs) were used to improve the voltage levels of the buses that were below the required standards.
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Wang, Zhen Po, Sheng Jie Shi, Yue Wang i Xiao Hui Sun. "The Simulation Analysis on Side Collision Safety of Electric Buses". Applied Mechanics and Materials 121-126 (październik 2011): 1130–37. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.1130.
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With energy and environmental issues outstanding, electric vehicles have got much room for developments, which also brings a lot of security risks different from the traditional internal combustion engine vehicle such as the electrolyte spillage; toxic fumes; electric shock and so on. This paper simulates the progress of a electric bus side collision with LS-DYNA, and analyzes its security mainly from aspects of the electrical injury and electrochemical injury: internal short-circuit occurs in battery monomer, external short-circuit outside the battery pack occurs or even cause a fire, BMS, fast fuse and other electronic components with too large deformation in a collision will lose its ability of monitoring external short-circuit of battery pack. Meanwhile, we analyze reasons for the three phenomena above and propose measures for improvement, fix methods and structure of the weak components in collision zone have been improved. Then this paper verifies vehicle security after improvement reducing the electrical injury and electrochemical injury the vehicle on passengers.
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Bhatti, Bilal Ahmad, Robert Broadwater i Murat Dilek. "Analyzing Impact of Distributed PV Generation on Integrated Transmission & Distribution System Voltage Stability—A Graph Trace Analysis Based Approach". Energies 13, nr 17 (1.09.2020): 4526. http://dx.doi.org/10.3390/en13174526.
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The use of a Graph Trace Analysis (GTA)-based power flow for analyzing the voltage stability of integrated Transmission and Distribution (T&D) networks is discussed in the context of distributed Photovoltaic (PV) generation. The voltage stability of lines and the load carrying capability of buses is analyzed at various PV penetration levels. It is shown that as the PV generation levels increase, an increase in the steady state voltage stability of the system is observed. Moreover, within certain regions of stability margin changes, changes in voltage stability margins of transmission lines are shown to be linearly related to changes in the loading of the lines. Two case studies are presented, where one case study involves a model with eight voltage levels and 784,000 nodes. In one case study, a voltage-stability heat map is used to demonstrate the identification of weak lines and buses.
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Zheng, Wei, Long Yue Zhang, Fu Bo Liang, Chao Ma i Yan Dong Xing. "A New Method to Optimize Locations of SVC Based on Risk and Static Load Margin". Advanced Materials Research 774-776 (wrzesień 2013): 1887–90. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.1887.
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A method was proposed selecting the location of SVC, considering the power system with large wind farms interconnected. The location can be determined by risk index, which comprises credibility and global severity, and static load margin simultaneously. The method could consider the weak links and buses under both fault and normal conditions thus make better contribution to the system security. Case study shows that the correctness and effectiveness of the proposed method, comparing with the usual one.
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Lorenzini, Giulio, Mehrdad Ahmadi Kamarposhti i Ahmed Amin Ahmed Solyman. "A Voltage Stability-Based Approach to Determining the Maximum Size of Wind Farms in Power Systems". International Journal of Design & Nature and Ecodynamics 16, nr 3 (30.06.2021): 245–50. http://dx.doi.org/10.18280/ijdne.160301.
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Current methods to determine the wind farms maximum size do not consider the effect of new wind generation on the Voltage Stability Margins (VSMs). Installing wind power in one area may affect VSMs in other areas of the power system. Buses with high VSMs before wind power injection may be converted into weak buses after wind power injections in other parts of power systems, which may lead to limited future wind farms expansion in other areas. In this paper, two methods are proposed to determine two new wind farms maximum size in order to maximize wind power penetration level. In both methods, the size of any new wind farm is determined using an iterative process which is increased by a constant value. Proposed methods were used in the IEEE 14-bus power system. The results of applying these new methods indicate that the second method results in higher maximum sizes than the first method.
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Bhongade, S., i Sachin Arya. "Optimal Capacitors in Radial Distribution System for Loss Reduction and Voltage Enhancement". Indonesian Journal of Electrical Engineering and Computer Science 2, nr 3 (1.06.2016): 566. http://dx.doi.org/10.11591/ijeecs.v2.i3.pp566-582.
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The work presented in this paper is carried out with the objective of identifying the optimal location and size (Kvar ratings) of shunt capacitors to be placed in radial distribution system, to have overall economy considering the saving due to energy loss minimization. To achieve this objective, a two stage methodology is adopted in this paper. In the first stage, the base case load flow of uncompensated distribution system is carried out. On the basis of base case load flow solution, Nominal voltage magnitudes and Loss Sensitivity Factors are calculated and the weak buses are selected for capacitor placement.In the second stage, Particle Swarm Optimization (PSO) algorithm is used to identify the size of the capacitors to be placed at the selected buses for minimizing the power loss. The developed algorithm is tested for 10-bus, 34-bus and 85-bus Radial Distribution Systems. The results show that there has been an enhancement in voltage profile and reduction in power loss thus resulting in much annual saving.
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Naik, S. D., M. K. Khedkar i S. S. Bhat. "Identification of weak buses and elements participation in voltage instability of large multi bus power system". International Journal of Power and Energy Conversion 4, nr 4 (2013): 339. http://dx.doi.org/10.1504/ijpec.2013.057030.
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Uche, Engr Obi, Fortunatus, Aghara, Jachimma i Prof Atuchukwu John. "Shunt Compensaton of the Integrated Nigeria’s 330KV Transimission Grid System". Volume 5 - 2020, Issue 9 - September 5, nr 9 (25.09.2020): 537–40. http://dx.doi.org/10.38124/ijisrt20sep230.
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The Nigerian Power system is complex and dynamic, as a result of this it is characterized by frequent faults and outages resulting to none steady supply of power to the teaming consumers. This has great effect on the activities and mode of living of Nigerians. The research work was carried out on contingency analysis on the existing integrated 330KV Nigeria grid system and to carry out a shunt compensation on the violated buses, the shutdown of Eket-Ibom line being the case study so as to determine the following; uncertainties and effects of changes in the power system, to recognize limitations that can affect the power reliability and minimize the sudden increase or decrease in the voltage profile of the buses through shunt compensation of buses. Determine tolerable voltages and thermal violation of +5% and -5% of base voltage 330 KV (0.95-1.05) PU and to determine the critical nature and importance of some buses. This is aimed at bridging the gap of proposing further expansion of the grid system which is not only limited by huge sum of finance and difficulties in finding right – of- way for new lines but also which faces the challenges of fixed land and longtime of construction. The data of the network was gotten and modeled. The power flow and contingency analysis of the integrated Nigeria power system of 51 buses (consisting of 16 generators and 35 loads) and 73 transmission lines were carried out using Newton-Raphson Load Flow (NRLF) method in Matlab environment, simulated with PSAT software. Shunt compensation of the weak buses were done using Static Var Compensator (SVC) with Thyristor Controlled Reactor- Fixed capacitor (TCR-FC) technique. Results obtained showed that the average voltage for base simulation was 326.25KV, contingency 323.67KV and compensation was 322.37 KV. Voltage violations for lower limit were observed at Itu as 309KV and Eket as 306.81 KV while violations for upper limit were recorded at Damaturu as 352.85KV, Yola as 353.62 KV, Gombe as 355.98KV, and Jos as 342.97 KV. However after shunt compensation there were improvements for the violations at lower limits and that of higher limit were drastically brought down as recorded below: Damaturu 329.93 KV, Jos 330 KV, Eket 327.2 KV, Gombe 333.55KV, Itu 330KV, and Yola 330.52KV
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Bhutta, Muhammad Shoaib, Muddassar Sarfraz, Larisa Ivascu, Hui Li, Ghulam Rasool, Zain ul Abidin Jaffri, Umer Farooq, Jamshed Ali Shaikh i Muhammad Shahzad Nazir. "Voltage Stability Index Using New Single-Port Equivalent Based on Component Peculiarity and Sensitivity Persistence". Processes 9, nr 10 (18.10.2021): 1849. http://dx.doi.org/10.3390/pr9101849.
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A voltage stability index is proposed using a new single-port equivalent depending on component peculiarity representation and sensitivity persistence to locate and determine long-term voltage instability in transmission and distribution power networks. The suggested single-port equivalent effectively represents the equivalence of various component types and assures the consistency of sensitivity information before and after the equivalence which is compulsory for the equivalent accuracy in estimating the voltage stability analysis. The stability index is derived from the new single-port equivalent to determine the system voltage instability. The proposed stability index is compared with indices based on virtual impedance and Thevenin impedance models. This new stability index shows more accuracy and effectiveness as compared to the indices based on virtual and Thevenin equivalent models. The index also determines the weak buses, where an improvement or functional measure can be used to reduce the system voltage instability. The validity of the proposed equivalent approach and stability index is presented by utilizing two radial systems, four IEEE systems and an actual system having bus size from five to 1010 buses.
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Mastinu, Giampiero, i Laura Solari. "Electric and biomethane-fuelled urban buses: comparison of environmental performance of different powertrains". International Journal of Life Cycle Assessment 27, nr 2 (12.01.2022): 238–54. http://dx.doi.org/10.1007/s11367-021-02013-w.
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Abstract Purpose The paper aims to promote the transition to low/zero emission of the local public transport, particularly, urban buses are taken into account. Method The life cycle assessment of electric and biomethane-fuelled urban buses is performed by exploiting SimaPro commercial software (v.9.1.1.). Attention is focused on powertrains. Both midpoint and endpoint analyses are performed. Referring to environmental impact, the best compressed biomethane gas (CBG) powertrain was compared to the best electric one. Additionally, the worst-case scenario has been considered for both CBG and electric powertrains. Results CBG powertrain outperforms the electric one if overall greenhouse gas emissions are considered. However, the electric powertrain seems promising for human health and ecosystem. Conclusions The environmental performance of the two powertrains is good. Both of the two technologies have strength and weak points that anyhow make them good candidates for a clean local public transport of the future. The analysis performed in the paper suggests a future investigation on hybrid electric-CBG powertrain. Actually, such a solution could benefit from both the strengths of the biomethane and the electric powertrain.
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Acharjee, Parimal. "Identification of voltage collapse points and weak buses under security constraints using hybrid particle swarm optimization technique". International Transactions on Electrical Energy Systems 23, nr 2 (3.01.2012): 230–48. http://dx.doi.org/10.1002/etep.657.
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Olabisi, Patrick O., i Gbenga Ayeni. "Voltage Quality Analysis on Power Transmission Networks: A Case Study of 330kV Power Transmission Networks in Nigeria". Journal of Engineering Research and Reports 25, nr 4 (20.06.2023): 42–50. http://dx.doi.org/10.9734/jerr/2023/v25i4901.
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The 330kV power transmission system in Nigeria is associated with numerous problems ranging from voltage instability, ageing network, long and weak transmission lines and insulators, absence of protection schemes on the distribution network, lack of spinning reserve to compensate for power shortages, obsolete substation equipment, and higher power losses which substantially affect the reliability of power supply in Nigeria. This study aimed at analysing this scenario and to propose stability improvement measures in the power Network. Voltage instability is a major factor responsible for several system collapse and blackout experienced in the country. This work used necessary data obtained from the National Control Centre (NCC) of Transmission Company of Nigeria (TCN) for load flow simulation with the help of MATLAB R2021a software. Newton-Raphson iterative technique was used to carry out the load flow analysis due to its ability to converge faster with less iteration than Gauss-seidel and fast decoupled iterative techniques. The simulation results revealed that buses 4 (Akangba), 5 (Jos), 7 (Ikeja-west), 10 (Alagbon), 19 (Damaturu), 23 (Sakette), 28 (Ajah), 33 (Oke-Aro), 34 (Ayede) and 42 (Lekki) violate the acceptable limits as its voltage magnitude falls below the standard limit of 0.95-1.05pu. It was also observed that buses 6 (Kaduna), 13 (Yola), 16 (Gombe), 22 (Kano) and 34 (Ayede) are close to the point of instability as their voltage magnitudes are between 0.95 and 0.96 pu. These buses need urgent compensation if stability improvement in the entire Nigerian transmission system is to be achieved.
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Narayana, P. Lakshmi, M. Venkatesan i S. Ravindra. "Fast Load Voltage Stability Index constrained PMU Placement for Complete Observability". International Journal of Engineering & Technology 7, nr 4.24 (27.11.2018): 20. http://dx.doi.org/10.14419/ijet.v7i4.24.21764.
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This paper proposes a Fast Load Voltage Stability Index (FLVSI) constrained Binary Integer Programming (BIP) method for Phasor Measurement Unit placement at optimal locations in network to obtain complete observability. Every load bus of network is considered to sort out weak load bus from proposed FLVSI approach. PMUs are constrained to place at weak load buses using BIP approach for observability of network. Zero Injection (ZI) modeling is suggested to reduce PMU placement locations in network. Single line outage or PMU loss constraints are formulated for placement of PMUs. Bus Redundancy Index (BRI) is formulated and considered for every bus of network. With and without ZI modeling under normal and line outage cases is compared to present effectiveness of approach. IEEE –14- 30-and 57- bus networks are tested with MATLAB Programming and compared with other methods to show its effectiveness.
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Mohamad Nor, Ahmad Fateh, i Marizan Sulaiman. "Voltage instability analysis based on modal analysis technique and artificial neural network". Indonesian Journal of Electrical Engineering and Computer Science 13, nr 3 (1.03.2019): 1274. http://dx.doi.org/10.11591/ijeecs.v13.i3.pp1274-1279.
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<span>One of the paramount importance in the operation of electrical power system operation order to sustain the equilibrium of the system is the stability of the load buses’ voltages. If the load buses voltages are not stable, this can cause serious problem especially power system blackout. This paper presents the analysis of voltage instability in electric power system by using modal analysis technique. However, one of the challenges of modal analysis is the intencive and complex calculation procedures. In order to overcome that, this paper implements Artificial Neural Network (ANN) to improve the implementation of modal analysis technique. ANN is used to determine the participation factors obtained from the modal analysis technique. The results show that modal analysis technique is able to show which bus is close towards experiencing voltage instability. In addition, the results also show that ANN is able to predict the values of participation factors. A load bus is considered a weak bus if the bus has high tendency towards experiencing voltage instability. IEEE-14 bus test power system has been chosen as the test power system.</span>
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Rasool, Ali Abdulqadir, Najimaldin M. Abbas i Kamal Sheikhyounis. "Determination of optimal size and location of static synchronous compensator for power system bus voltage improvement and loss reduction using whale optimization algorithm". Eastern-European Journal of Enterprise Technologies 1, nr 8(115) (25.02.2022): 26–34. http://dx.doi.org/10.15587/1729-4061.2022.251760.
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Power systems are usually expected to become heavily loaded as the demand for electrical energy grows and economic consideration limits the installation of additional transmission and generating capacity. Keeping the bus voltage in the power system within the standard permissible limits is an important concern to improve the voltage stability and avoid voltage collapse of the whole power system. The common and effective way to achieve this purpose is by adding flexible AC transmission line devices to the power system. One of these devices is static synchronous compensator. In this paper an approach is proposed to find optimal location and size of static synchronous compensator for improving bus voltage in the power system. A load flow is conducted to identify the low voltage buses which are the weak buses in the system and they are considered as suitable buses for static synchronous compensator connection. An objective function is formulated for optimization process which contains four parts, the voltage deviation, static synchronous compensator size, active and reactive power losses of the whole power system. Whale optimization algorithm is used for the optimization process. The proposed approach is applied on the real power system of Kurdistan Region using power system simulator for engineering software for simulating the power system and finding the optimal size and location of static synchronous compensator for bus voltage improvement. The results are encouraging for applying the approach to any power system. What distinguishes this method is that it accomplishes two things, namely reducing the bus voltage deviation to zero which means that all bus voltages are within the permissible limits and minimizing losses as well.
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Ben-Asher, Yosi, i Assaf Schuster. "Single Step Undirected Reconfigurable Networks". VLSI Design 9, nr 1 (1.01.1999): 17–28. http://dx.doi.org/10.1155/1999/71739.
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The reconfigurable mesh (RN-MESH) can solve a large class of problems in constant time, including problems that require logarithmic time by other, even shared memory, models such as the PRAM with a similar number of processors [3]. In this work we show that for the RN-MESH these constants can always be reduced to one, still using a polynomial number of processors. Given a reconfigurable mesh that computes a set of values in constant time, we show that it can be simulated by a single step reconfigurable mesh with maximum size that is polynomial in the size of the original mesh. The proof is constructive, where the construction of the single step RN-MESH holds for the relatively weak undirected RN-MESH model. In this model broadcasts made on buses arrive at all nodes that belong to the undirected connected component of the transmitting processor. A result similar to the one that is obtained in this work was previously obtained for the directed reconfigurable mesh model (DRN) [5]. However, the construction for the DRN-MESH relies on the fact that the buses are directed, and thus cannot be applied to the undirected case. In addition, the construction presented here is simpler and uses significantly fewer processors than the one obtained for the DRN-MESH.
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Amagai, Kenji, Hiroto Kotake, Masahiro Munemura, Sawako Shigeto i Masayuki Horio. "Co-development of Low-speed Electric Community Buses for Local Area Revitalization". Journal of Energy and Power Technology 05, nr 01 (2.02.2023): 1–14. http://dx.doi.org/10.21926/jept.2301005.
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This paper describes the development of low-speed electric community buses (LSECBs) designed by the author's group and their spread situation in Japan. LSECBs are electric vehicles that can travel on public roads at speeds of less than 5.56 m/s (20 km/h). The university, local government, local businesses, and residents with a co-design approach developed the LSECBs. They have various advantages such as safety due to low speed and low energy consumption. In particular, the LSECBs have features not found in ordinary vehicles, such as the ability to friendly talk with other passengers in the vehicle and to see the surroundings. The purpose of using LSECBs is mostly for sightseeing, but they are also used to enhance the mobility of elderly people in the community. In Japan, public transportation plans are formulated by each local government, but local governments with weak finances do not provide sufficient financial support to the companies responsible for public transportation. As a result, public transportation services have been reduced or eliminated due to the business conditions of private companies, and many elderly people with reduced mobility, called "people with shopping difficulties," have been left behind. Under these situations, it is necessary to discuss what kind of contribution LSECBs can make. Moreover, the LSECBs require special driving methods so as not to cause traffic congestion when mixed with other ordinal vehicles. In this paper, we report on the development concept, features of the LSECBs, their special driving method, positioning as a transportation policy, and their potential as stainable mobility.
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KAUFMANN, MICHAEL, HEIKO SCHRÖDER i JOP F. SIBEYN. "ROUTING AND SORTING ON RECONFIGURABLE MESHES". Parallel Processing Letters 05, nr 01 (marzec 1995): 81–95. http://dx.doi.org/10.1142/s0129626495000084.
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We consider routing and sorting problems on mesh connected processor arrays under a very weak model of reconfiguration: we allow only uni-directional row or column buses, point-to-point communication, one-port-at-the-time serve by each processor. We present a scheme which is asymptoticly optimal for k-k sorting, for any arbitrary k > 0. It works optimally on meshes of arbitrary dimensions d, from the linear array to hypercubic networks with d < n1/3. The algorithm can also be used to perform k-k routing in the same time bound. We give an alternative scheme for permutation routing, which is asymptoticly slower, but has much better performance for realistic problem sizes.
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Lu, Xiao Jun, Kai Wen Zeng, Shi Wu Liao, Jin Yu Wen, En Lu, Fei Long i Ning Wang. "Novel Indexes and Method for Power Grid Blackout Risk Assessment". Applied Mechanics and Materials 556-562 (maj 2014): 6665–68. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.6665.
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A set of blackout risk assessment indexes is established according to Electricity Accident (Incident) Investigation Procedures of China Southern Power Grid (CSPG) (pilot) and Guide on Operational Risk Evaluation of CSPG, which can calculate risk values of electricity accidents (incidents). The calculation process is discussed in detail. Based on the proposed indexes and OPA blackout model, a blackout risk assessment method for power system is put forward, with which blackout risk for all 500kV buses in Guangdong Power Grid are evaluated. Weak areas in power system are identified and their inducements are analyzed. The identification results accord with actual system long-term operation experience, which verifies the correctness of the indexes and method.
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Badi, Manjulata, Sheila Mahapatra, Bishwajit Dey i Saurav Raj. "A Hybrid GWO-PSO Technique for the Solution of Reactive Power Planning Problem". International Journal of Swarm Intelligence Research 13, nr 1 (styczeń 2022): 1–30. http://dx.doi.org/10.4018/ijsir.2022010104.
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Over the years the optimization in various areas of power system has immensely attracted the attention of power engineers and researchers. RPP problem is one of such areas. This is done by the placement of reactive power sources in the weak buses and thereafter minimizing the operating cost of the system which is directly dependent on the system transmission loss. The work proposed in this article utilizes FVSI method to detect the weak bus. GWO-PSO is proposed in the current work for providing optimal solution to RPP problem. To test the efficacy of the proposed technique, comparative analysis is then performed among the variants of PSO and hybrid GWO-PSO. The optimal solution rendered by the proposed method is compared with other heuristic algorithms. The proposed method of GWO-PSO generates a reduction of 4.25% in operating cost for IEEE 30 bus and 5.99% for New England 39 bus system. The comparison thus yields that the GWO-PSO hybrid method is superior in generating optimality, diversity and is efficient to generate solution strategies for RPP even in a practical power network.
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Hussain, S. M. Suhail. "Identification of weak buses using Voltage Stability Indicator and its voltage profile improvement by using DSTATCOM in radial distribution systems". IOSR Journal of Electrical and Electronics Engineering 2, nr 4 (2012): 17–23. http://dx.doi.org/10.9790/1676-0241723.
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Nadeem, Muhammad, Kashif Imran, Abraiz Khattak, Abasin Ulasyar, Anamitra Pal, Muhammad Zulqarnain Zeb, Atif Naveed Khan i Malhar Padhee. "Optimal Placement, Sizing and Coordination of FACTS Devices in Transmission Network Using Whale Optimization Algorithm". Energies 13, nr 3 (8.02.2020): 753. http://dx.doi.org/10.3390/en13030753.
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Flexible AC Transmission Systems (FACTS) play an important role in minimizing power losses and voltage deviations while increasing the real power transfer capacity of transmission lines. The extent to which these devices can provide benefits to the transmission network depend on their optimal location and sizing. However, finding appropriate locations and sizes of these devices in an electrical network is difficult since it is a nonlinear problem. This paper proposes a technique for the optimal placement and sizing of FACTS, namely the Thyristor-Controlled Series Compensators (TCSCs), Shunt VARs Compensators (SVCs), and Unified Power Flows Controllers (UPFCs). To find the optimal locations of these devices in a network, weak buses and lines are determined by constructing PV curves of load buses, and through the line stability index. Then, the whale optimization algorithm (WOA) is employed not only to find an ideal ratings for these devices but also the optimal coordination of SVC, TCSC, and UPFC with the reactive power sources already present in the network (tap settings of transformers and reactive power from generators). The objective here is the minimization of the operating cost of the system that consists of active power losses and FACTS devices cost. The proposed method is applied to the IEEE 14 and 30 bus systems. The presented technique is also compared with Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The findings showed that total system operating costs and transmission line losses were considerably reduced by WOA as compared to existing metaheuristic optimization techniques.
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Adegoke, Samson Ademola, Yanxia Sun i Zenghui Wang. "Minimization of Active Power Loss Using Enhanced Particle Swarm Optimization". Mathematics 11, nr 17 (24.08.2023): 3660. http://dx.doi.org/10.3390/math11173660.
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Identifying the weak buses in power system networks is crucial for planning and operation since most generators operate close to their operating limits, resulting in generator failures. This work aims to identify the critical/weak node and reduce the system’s power loss. The line stability index (Lmn) and fast voltage stability index (FVSI) were used to identify the critical node and lines close to instability in the power system networks. Enhanced particle swarm optimization (EPSO) was chosen because of its ability to communicate with better individuals, making it more efficient to obtain a prominent solution. EPSO and other PSO variants minimized the system’s actual/real losses. Nodes 8 and 14 were identified as the critical nodes of the IEEE 9 and 14 bus systems, respectively. The power loss of the IEEE 9 bus system was reduced from 9.842 MW to 7.543 MW, and for the IEEE 14 bus system, the loss was reduced from 13.775 MW of the base case to 12.253 MW for EPSO. EPSO gives a better active power loss reduction and improves the node’s voltage profile than other PSO variants and algorithms in the literature. This suggests the feasibility and suitability of EPSO to improve the grid voltage quality.
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Mokred, Salah, Yifei Wang i Tiancong Chen. "Modern voltage stability index for prediction of voltage collapse and estimation of maximum load-ability for weak buses and critical lines identification". International Journal of Electrical Power & Energy Systems 145 (luty 2023): 108596. http://dx.doi.org/10.1016/j.ijepes.2022.108596.
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Salman, Ghassan Abdullah, Hatim G. Abood i Mayyadah Sahib Ibrahim. "Improvement the voltage stability margin of Iraqi power system using the optimal values of FACTS devices". International Journal of Electrical and Computer Engineering (IJECE) 11, nr 2 (1.04.2021): 984. http://dx.doi.org/10.11591/ijece.v11i2.pp984-992.
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The detection of potential voltage collapse in power systems is essential to maintain the voltage stability in heavy load demand. This paper proposes a method to detect weak buses in power systems using two stability indices: the voltage stability margin factor (dS/dY) and the voltage collapse prediction index (VCPI). Hence, the paper aims to improve the voltage stability of Iraqi transmission grid by allocating FACTS devices in the optimal locations and optimal sizes. Two types of FACTS are used in this paper which are Thyristor controlled series compensator (TCSC) and static var compensator (SVC). The objective function of the problem is fitted using particle swarm optimization (PSO). The proposed method is verified using simulation test on Diyala-132 kV network which is a part of the Iraqi power system. The results observed that improvement the voltage stability margin, the voltage profile of Diyala-132 kV is increased and the power losses is decreased.
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Hussein, Husham Idan, Hassan Saadallah Naji i Ghassan Abdullah Salman. "Voltage stability assessment prediction using a guide strategy-based adaptive particle swarm optimisation-neural network algorithm". International Journal of Power Electronics and Drive Systems (IJPEDS) 13, nr 4 (1.12.2022): 2199. http://dx.doi.org/10.11591/ijpeds.v13.i4.pp2199-2206.
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<span lang="EN-US">In this work, the indicators of electrical power network stability and voltage stability (VS) are discussed and developed with the aim of using a power transfer stability index (PTSI) indicator as a predictor for voltage stability (VS) in electrical power networks. The power transfer stability index (PTSI) was thus used to detect abnormally weak voltages in buses within such power system networks (weak). The target data are obtained using the Newton Raphson method (NR) and include magnitude, phase angle, and active and reactive power. A new adaptive particle swarm optimization-neural network algorithm based on a guiding strategy (GSAPSO-NN) was also used to achieve the goal of the paper by improving the mixed particle updates and the weightings of the neural network to decrease the search time. All results were then compared with actual values as calculated using the PTSI NR method. The final results show only simple differences or approximately the same values using both the proposed and the classical methods. The MATLAB-PSAT package was employed to obtain most of these results and the testing of the new method was done on the IEEE14 bus system as well as the Iraqi 24-bus power system. The effectiveness validation of the new hybrid method for assessing voltage stability was thus achieved.</span>
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Hu, Yan Mei, Jun Yong Wu, Fang Li i Hong Jun Fu. "Impacts of UHVDC from Hami to Zhengzhou on Voltage Stability of Henan Power Grid". Applied Mechanics and Materials 347-350 (sierpień 2013): 1435–39. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1435.
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Based on the planning data of Henan power grid in 2014, the impacts of 800kV UHVDC from Hami to Zhengzhou on static voltage stability of Henan power grid are analyzed in details. Firstly, this paper introduces the principle of voltage stability analysis, the stability margin index has been established. Secondly, the analysis of static voltage stability for Henan power grid before and after the UHVDC from Hami to Zhengzhou putting into operation is carried out, the weak buses and regions in Henan power grid are pointed out. Finally, the operation patterns of Henan power grid after the UHVDC putting into operation are classified and optimized. Simulation results show that the improper operation pattern may significantly deteriorate the static voltage stability of power grid. The operation patterns of HVDC power multi-channel transferring from Henan to Central China grid combined with partly internal consumption are favorable to improve the static voltage stability of the whole system. The analysis results provide theoretical basis for the future operation of Henan grid.
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Le, Thi Hong Nhung, Trieu Tan Phung, Trong Nghia Le i Phuong Nam Nguyen. "Load Shedding Technique for Power System Using Neural Network Improved by Cuckoo Search Algorithm". Journal of Technical Education Science, nr 78A (28.08.2023): 63–72. http://dx.doi.org/10.54644/jte.78a.2023.1351.
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The present paper introduces a load shedding methodology that leverages an upgraded neural network that relies on the Cuckoo search (CS) optimization algorithm to compare the efficiency and applicability with other methods in terms of speed and feasibility. The proposed method will be tested on the IEEE-37 bus system. The results of the method are compared with other optimization methods. Thereby, this method gives good results and feasibility in application. The criteria of voltage are considered, specifically the sensitivity index dV/dQ is proposed to find weak buses in the system that need to be relieved of the active power burden. Then, the shedding priority bus ranking is created to ensure the most favorable load shedding plan for the system to maintain voltage stability. Besides, the frequency parameter is also considered to calculate the optimal amount of shed load. The model system was tested by using POWERWORLD software. After comparing the results with other methods outlined in the paper, it has been determined that the proposed approach is highly effective for optimizing grid shedding in the system.
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Fairushina, I. F., E. R. Kirillova, D. I. Abdulganieva, E. V. Sukhorukova i E. I. Mukhametshina. "Psoriatic arthritis: clinical and ultrasound parallels". Modern Rheumatology Journal 14, nr 3 (21.09.2020): 27–33. http://dx.doi.org/10.14412/1996-7012-2020-3-27-33.
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Objective: to assess the relationship of the clinical characteristics and laboratory inflammatory markers to the ultrasound signs of synovitis and enthesitis in patients with psoriatic arthritis (PsA).Patients and methods. Examinations were made in 63 patients diagnosed with PsA according to the 2006 Classification Criteria for Psoriatic Arthritis (CASPAR) criteria. Among the patients, the majority were females (54.2%); the mean age was 42.9±10.3 years; the median (Me) PsA duration was 7 [3; 10] years; Me Disease Activity in Psoriatic Arthritis (DAPSA) was 16.5 [11.6; 25] years.All the patients underwent estimation of tender joint count, swollen joint count, tender entheseal count, inter alia using the Leeds Enthesitis Index (LEI), Maastricht Ankylosing Spondylitis Enthesis Score (MASES), and Spondyloarthritis Research Consortium of Canada (SPARCC). The investigators determined PsA activity by DAPSA and the prevalence and severity of psoriasis by the Psoriasis Area and Severity Index (PASI) and also estimated erythrocyte sedimentation rate (ESR) and high-sensitivity CRP (hs-CRP) levels. Ultrasonography was used to assess bilateral upper and lower limb joints, by calculating joint counts (JC) with synovitis signs (SJC), as well as tendon and ligament entheses (a total number of 54 in one patient), by determining the presence of vascularized enthesis count (VEC) and structurally changed enthesis count (SCEC) and using the ultrasound indices (Glasgow Ultrasound Enthesitis Scoring System (GUESS), Belgrade Ultrasound Enthesitis Score (BUSES), Madrid Sonography Enthesitis Index (MASEI), Sonographic Enthesitis Index (SEI)).Results and discussion. There were no significant differences in the frequency of damage to the upper (15.7%) and lower (19.3%) limb joints (p>0.05), whereas inflammation in the entheses of the lower limbs (23.2%) was significantly more common than that in the upper limbs (15.3%) (p<0.01). A weak relationship was established between SPARCC and SEI (r=0.276; p<0.05). A positive correlation was found between VEC and hs-CRP levels (r=0.323, p=0.01), ESR (r=0.332, p<0.01). Ultrasound imaging showed that SJC (p<0.01), enthesitis count (p<0.01), and SCEC (p<0.05) increased with age. The relationship between SCEC and GUESS (r=0.724; p<0.01) and that between the VEC and BUSES (r=0.562, p<0.01) proved to be more pronounced.Conclusion. Ultrasound imaging indicates that the entheses of the lower limbs are more frequently affected in patients with PsA. There is no relationship between DAPSA and ultrasound inflammatory changes in the joints and extra-articular structures. A strong relationship is established between enthesiseal structural and inflammatory changes and GUESS and BUSES, respectively, which allows one to recommend the use of these indices for assessing enthesitis in PsA. Entheseal vascularization associated with inflammatory markers (hs-CRP, ESR) (p<0.05) is a manifestation of PsA activity regardless of age and DAPSA.
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Flórez Valero, Carlos Fabián, i Pedro Luís Jiménez Póveda. "Determining adjustment variables for rationalising a design for fleet operation in public passenger transport". Ingeniería e Investigación 27, nr 2 (1.05.2007): 85–91. http://dx.doi.org/10.15446/ing.investig.v27n2.14834.
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This investigation was aimed at establishing aspects leading to adjusting the operational design of public transport fleet operation to make it more profitable for private investors. Data obtained from more than a year’s operation by the Alianza Sat S.A. was used (this being a bus-company alliance grouping about 100 buses from some of Bogota’s collective transport companies) for carrying out the present investigation regarding fleet administration and operation. Simply implementing conventionally-designed routing plans is not enough for rationalising fleet operation, as most public collective transport is not directly operated by companies The Alianza Sat S.A. bus fleet was used for testing hypotheses demonstrating that current operational design for the company’s routes (in Bogota’s current public transport market conditions) leads to reducing the company’s income. The investigation revealed that public passenger transport bus fleet revenue can be increased if aspects different to those considered in standard route design methodology are controlled. The investigation has determined alternative rationalisation for operational collective public passenger transport company design regarding adjusting aspects such as the demand pattern, operating scheme, route variability, etc. This will provide an innovative and useful tool for rationalising the operational design of bus routes operating in cities having weak public transport control and excess bus supply.
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Haidari, Moazzam, i Vivek Kumar. "Restoration of a new age power distribution system". International Journal of Power Electronics and Drive Systems (IJPEDS) 13, nr 4 (1.12.2022): 2079. http://dx.doi.org/10.11591/ijpeds.v13.i4.pp2079-2085.
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The new age transformed distribution system became the most popular content in the literature. In that regard a simulation is attempted for the load flow with dynamically changing system data. Any topic of interest like electrical vehicle, distributed generators, FACTS devices were generalized and considered as an element and placed at different possible locations to observe their effect. The outcomes of the work were generalized to re-consider on site. As the power industry is undergoing a drastic change throughout the world. Restoration of a distribution system along with switching sequence has become a challenging task. In the last half of the twentieth century, analysis of transmission system was the prime concern and faced many challenges to power engineers. The chosen equivalent IEEE 33-bus electric power distribution system has been considered to analyze the system properties such as its maximum capacity, operating limits, restoration issues. The placement of static var compensator (SVC) was experimented for each and every bus. Considering the minimization of total power loss as a prime objective, the best location was found. This analysis also suggested a ranking of different buses and can be helpful in deciding the switching sequence, provided in case of fault, weak area clustering is done. So, congestion is managed in this distribution system.
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Hernandez, Michael, Kara M. Kockelman, James O. Lentz i Jooyong Lee. "Emissions and noise mitigation through use of electric motorcycles". Transportation Safety and Environment 1, nr 2 (1.11.2019): 164–75. http://dx.doi.org/10.1093/tse/tdz013.
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Abstract Gasoline-powered motorcycles contribute disproportionately to traffic noise and emissions, so motorcycle electrification merits investigation. Recent advances in battery efficiency allow electric motorcycles (EMCs) to join electric cars and bicycles as a viable consumer option. This study quantifies noise and emissions using both simulations and experimental data, examines the factors that make EMCs big offenders and uses popular EMC specifications to estimate the costs and benefits of electrification in the USA. Motorcycles produce more CO, CH4, NOx, HC and particulate matter than passenger vehicles per vehicle-mile travelled. Due to limited regulation of motorcycles and weak enforcement, the perceived noise of motorcycles exceeds that of most other vehicles, being roughly double that of automobiles at speeds of over 30 mph and surpassing even that of medium trucks and buses at speeds of over 50 mph, at which point motorcycles exceed the 80 dBA US standard limit. Electrification can resolve such issues, although range limitations and high prices are presently a barrier to widespread adoption. In order to realize these environmental benefits, it is important that electrification occur with a corresponding shift away from coal as an energy source. Stricter emission regulations and stronger enforcement of existing prohibitions on certain forms of customization could also reduce the outlier status of gasoline-powered motorcycles.
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Sundarajoo, Sharman, i Dur Soomro. "Particle Swarm Optimization Trained Feedforward Neural Network for Under-Voltage Load Shedding". ECTI Transactions on Electrical Engineering, Electronics, and Communications 21, nr 2 (27.06.2023): 249825. http://dx.doi.org/10.37936/ecti-eec.2023212.249825.
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This paper suggests an under-voltage load shedding (UVLS) approach to avoid voltage collapse in stressed distribution systems. Prior to a blackout, a failing system reaches an emergency state, and UVLS is executed as the final option to prevent voltage collapse. Hence, this article introduces an optimal UVLS method using a feedforward artificial neural network (ANN) model trained with the particle swarm optimization (PSO) algorithm to obtain the optimal load shedding amount for a distribution system. PSO is used to obtain the best topology and optimum initial weights of the ANN model to enhance the precision of the ANN model. Thus, the dispute between the optimum fitting regression of the allocation of ANN nodes and computational time was disclosed, while the MSE of the ANN model was minimized. Moreover, the proposed method uses the stability index (SI) to identify the weak buses in the system following an emergency state. Different overload scenarios are examined on the IEEE 33-bus distribution network to validate the efficacy of the suggested UVLS scheme. A comparative study is performed to further assess the performance of the proposed technique. The comparison indicates that the recommended method is effective in terms of voltage stability and remaining load.
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Dubey, Rabindra Nath. "Impact of fear of crimes on public transport usage: A case study of Delhi". National Geographical Journal of India 66, nr 3 (30.09.2020): 247–58. http://dx.doi.org/10.48008/ngji.1745.
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Delhi Transport Corporation (DTC and Delhi Metro-Rail System (DMRS) are two important public transport systems in Delhi. The DMRS has been attractive in respect to ridership but in 2015 it has shown a decrease in its ridership. It has also been found that ridership of the bus service, the most important public transport system for the poor in Delhi, has decreased over time whereas the numbers of private vehicles have recorded phenomenal increase resulting in traffic congestions and pollution problems in the city. The purpose of this study is to explore the role of the fear of crimes along with other reasons for decreasing trends in the usage of public transport in Delhi. The study is based on people opinion and perception for which 350 persons were interviewed with the structured questionnaire from ten transit places having varied socio-economic conditions. Fear of crimes within buses/coaches is considered an important reason for not using public transport in western countries but as per this study, the same is not true in the case of Delhi. Role of fear of crimes along with other factors was verified with the spearman’s correlation coefficient. The weak negative correlation has been found between the preference to public bus services and the fear of crimes; the crowing; the unavailability. It indicates that along with these other factors are equally responsible for the choice of public transports in Delhi.
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Matthews, James C., Chalida Chompoobut, Panida Navasumrit, M. Anwar H. Khan, Matthew D. Wright, Mathuros Ruchirawat i Dudley E. Shallcross. "Particle Number Concentration Measurements on Public Transport in Bangkok, Thailand". International Journal of Environmental Research and Public Health 20, nr 7 (29.03.2023): 5316. http://dx.doi.org/10.3390/ijerph20075316.
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Traffic is a major source of particulate pollution in large cities, and particulate matter (PM) level in Bangkok often exceeds the World Health Organisation limits. While PM2.5 and PM10 are both measured in Bangkok regularly, the sub-micron range of PM, of specific interest in regard to possible adverse health effects, is very limited. In the study, particle number concentration (PNC) was measured on public transport in Bangkok. A travel route through Bangkok using the state railway, the mass rapid transport underground system, the Bangkok Mass Transit System (BTS) Skytrain and public buses on the road network, with walking routes between, was taken whilst measuring particle levels with a hand-held concentration particle counter. The route was repeated 19 times covering different seasons during either morning or evening rush hours. The highest particle concentrations were found on the state railway, followed by the bus, the BTS Skytrain and the MRT underground with measured peaks of 350,000, 330,000, 33,000 and 9000 cm−3, respectively, though particle numbers over 100,000 cm−3 may be an underestimation due to undercounting in the instrument. Inside each form of public transport, particle numbers would peak when stopping to collect passengers (doors opening) and decay with a half-life between 2 and 3 min. There was a weak correlation between particle concentration on bus, train and BTS and Skytrain with carbon monoxide concentration, as measured at a fixed location in the city.
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Ghadban, Ahmed Majeed, Ghassan Abdullah Salman i Husham Idan Hussein. "Assessment of voltage stability based on power transfer stability index using computational intelligence models". International Journal of Electrical and Computer Engineering (IJECE) 11, nr 4 (1.08.2021): 2790. http://dx.doi.org/10.11591/ijece.v11i4.pp2790-2797.
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<span>In this paper, the importance of voltage stability is explained, which is a great problem in the EPS. The estimation of VS is made a priority so as to make the power system stable and prevent it from reaching voltage collapse. The power transfer stability index (PTSI) is used as a predictor utilized in a PSN to detect the instability of voltages on weakened buses. A PSI is used to obtain a voltage assessment of the PSNs. Two hybrid algorithms are developed. The (CA-NN) and the (PSO-NN). After developing algorithms, they are compared with the actual values of PTSI NR method. The algorithms installed on the 24 bus Iraqi PS. The actual values of PTSI are the targets needed. They are obtained from the NR algorithm when the input data is V<sub>i</sub>, δ<sub>i</sub>, P<sub>d</sub>, Q<sub>d</sub> for the algorithm. The results indicate that a weak bus that approaches voltage collapse and all results were approximately the same. There is a slight difference with the actual results and demonstrated classical methods are slower and less accurate than the hybrid algorithms. It also demonstrates the validation and effectiveness of algorithms (CA-NN, and PSO-NN) for assessing voltage-prioritizing </span><span>algorithms</span><span> (CA-NN). The MATLAB utilized to obtain most of the results.</span>