Search results

To achieve the optimum performance of electric transmission power system performance, the possibility of generators’ failure and the consequences are amongst the most important and real assumptions which should be taken into consideration. This paper aims to recognize the most influential factors on generators’ failures that can have a deep effect on the total cost and environmental issues. The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow.

The data used in this study are gathered from a real case in USA in first step, the influential generator points that their failure has a significant effect on the objective function, have been recognized. Then, different failure scenarios are defined, and the optimum values in each of these scenarios through the GAMS modeling software are found. Consequently, by using a two-level factorial design approach, the critical generators across the power grid are determined.

The results show that by using such information, it is possible to detect the significant nodes in the power system grid and have a better maintenance plan. In addition, by means of this analysis and changing the capacity of main generators, it is possible to significantly reduce the operation costs. By comparing the indexes in case of the generator’s location, it seems that some of them are critical because of their capacity and position in the network (as their failure causes infeasibility in the model). Also, some of these deficiencies caused considerable index changes and critical consequences.

The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow.

This paper endeavors to recognize the most influential factors on generators’ failures that can have a deep effect on the total cost and environmental issues.

The integrated proposed approach is useful for investigating the generators’ failure effects on the performance of electric power transmission grids from the economic and environmental perspectives. In other words, the cost and pollution minimization policies are considered to decrease the unfavorable generators’ failure effects on electric power flow.

The paper aims to discuss problems of power and energy losses in a double-circuit overhead transmission line. It was observed from energy meters’ readings, that in such a line, active power losses can be measured as “negative”. The “negative” active power losses appear when the active power injected to the circuit is lower than the active power received at the circuit end. The purpose of this paper is to explain this phenomenon.

Theoretical considerations based on mathematical model of the transmission line of π-type confirming that effect are presented. Power losses related to series impedance of the line and to shunt admittance are calculated. The theoretical considerations are confirmed by measurements done on the real transmission line.

The calculations allow to indicate components of the active power losses, i.e. related to electromagnetic coupling among wires of a given circuit, related to electromagnetic coupling between circuits and related to shunt capacitance asymmetry. The authors indicate the influence of the line/wires geometry on the active power losses in a double-circuit overhead transmission line.

Explanation of the effect of “negative” active power losses’ measurement in a double-circuit overhead transmission line is provided in this paper.

Detection of deformation of devices in high voltage electricity transmission line systems is an important issue in terms of economy and reuse. This study is aimed to detect devices that are deformed or thought to have suffered due to environmental and electrical reasons.

In this experimental study, it was ensured that the sound and deformed insulators used in energy transmission lines were determined by the analysis of the sounds obtained by using the impact method. Equal intensity impact was applied to the isolator using the pendulum and the resulting sound noise signal analyses were made using power spectral density (PSD), magnitude scalogram (MS), multitape power spectrum density (MPSD) and continuous wavelet transform (CWT) methods in the study. In the analysis results, the isolators that are not visible to the eye and have certain damage were successfully separated from the intact insulators. Especially, MPSD and CWT analysis results are quite satisfactory.

Damage analysis of insulators used in electricity transmission lines has been made. A total of 40 insulators were examined in two categories in their group, both damaged and not damaged. Data collection system was established. The data obtained from the data collection system were analysed and compared using four analysis methods. PSD, MS, MPSD and CWT analyses were made in the study. All the analyses carried out generally contain features that distinguish damaged and undamaged insulators from each other, the most successful results are MS and CWT results. CWT results are very successful in terms of time and amplitude, and it has been proposed as a method that can be used to separate damaged and undamaged insulators.

It can be suggested as a result of experimental tests that the results of CWT analysis can be used in the pulse noise method in isolators to be tested for reuse in electrical power transmission lines.

This paper aims to survey the need for full capacity utilisation of transmission lines in power systems network operations. It proposes a review of the N-1 security criterion that does not ensure reliable dispatch of optimum power flow during outage contingency. The survey aims to enlarge the network capacity utilisation to rely on the entire transmission lines network operation.

The paper suggests transmission line switching (TLS) approach as a viable corrective mechanism for power dispatch. The TLS process is incorporated into a constraint programming language extension optimisation solver that selects the switchable line candidates as integer variables in the mixed integer programming problem.

The paper provides a practical awareness of reserve capacity in the lines that provide network security in outage contingency. At optimum power flow dispatch, the TLS is extended to optimal transmission line switching (OTLS) that indicates optimal capacity utilisation (OCU) of the available reserve capacity (ARC) in the network lines.

Computational efficiency influenced the extension of the OTLS to optimal transmission switching of power flow (OTSPF). The application of OTSPF helps reduce the use of flexible AC transmission systems (FACTS) and construction of new transmission lines..

The paper surveys TLS efforts in network capacity utilisation. The suggested ARC fulfils the need for an index with which the dispatchable lines may be identified for the optimal capacity utilisation of transmission lines network.

The non‐storable nature of electricity and the increasing complexity of financial instruments as a tool for hedging against risk make the area of research very useful in the real world. Many power portfolio optimization problems have been developed to combat the issue of risk tolerance, but very few (if any) have included transmission constraints. The purpose of this paper is to consider optimization of portfolios of real and contractual assets, including derivative instruments, in a multi‐period setting where transmission constraints also exist.

Rather than using a flowgate constraint as a representation of transmission congestion, the authors use fixed transmission rights. A model is introduced that involves a three‐node unidirectional network in order to evaluate the significance of transmission constraints. Data from the PJM, which is located in the eastern USA, were used for model implementation.

The stochastic nonlinear mixed‐integer model presented shows that transmission constraints and fixed transmission rights can have a significant effect on the choices a utility will make when dealing with power procurement. It is demonstrated that the inclusions drastically decrease the value of the objective function.

Conditional value at risk (CVaR) was chosen over VaR as a risk measurement for two different reasons. First, it is important to have a good representation of the trade‐off between the best expected profit and the volatility experienced when obtaining that profit. Second, it provides protection against very undesirable scenarios that may occur with low probability. In order to simplify the fixed transmission rights contracts, a three‐node network is used with unidirectional flow.

When markets were regulated, transmission lines were owned and operated by local utilities, and all power sent over the lines was either owned by the operating utility or wheeled for another utility based on existing agreements. With the advent of deregulation, utilities were forced to wheel other companies' power, which introduced more risk in terms of transmission constraints.

The contribution of this research is to help companies not only hedge the risk of unknown power prices but also unknown transmission congestion. One distinctive feature of the authors' research is to expand upon existing “power portfolio optimization with risk” literature by introducing a transmission constraint into the model. Historically, transmission congestion has been modeled in different ways, including flowgates, transmission rents and fixed transmission rights.

This paper aims to propose a novel methodology for optimal voltage source converter (VSC) station installation in hybrid alternating current (AC)/direct current (DC) transmission networks.

In this analysis, a unified power flow model has been developed for the optimal power flow (OPF) problem for VSC-based high voltage direct current (VSC-HVDC) transmission network and solved using a particle swarm optimization (PSO) algorithm. The impact of the HVDC converter under abnormal conditions considering N-1 line outage contingency is analyzed against the congestion relief of the overall transmission network. The average loadability index is used as a severity indicator and minimized along with overall transmission line losses by replacing each AC line with an HVDC line independently.

The developed unified OPF (UOPF) model converged successfully with (PSO) algorithm. The OPF problem has satisfied the defined operational constraints of the power system, and comparative results are obtained for objective function with different HVDC test configurations represented in the paper. In addition, the impact of VSC converter location is determined on objective function value.

A novel methodology has been developed for the optimal installation of the converter station for the point-to-point configuration of HVDC transmission. The developed unified OPF model and methodology for selecting the AC bus for converter installation has effectively reduced congestion in transmission lines under single line outage contingency.

This paper aims to assess all the Brazilian electric power transmission line auctions occurred between 1999 and 2017.

A copula-based Roy/endogenous switching regression model is used. The suitability of this model is twofold: it takes into account the selection bias problem involving auctions data and it allows more flexibility in modeling the joint distribution between the unobserved components of the selection and outcome equations; thus, normal distribution assumptions are not needed.

The main results suggest that stated-owned companies have the highest probability of winning an auction, and there is a non-competitive behavior among the players in the auction. The results also suggest some departure from joint normality in the data.

The copula-based sample selection approach used in this paper is consistent under non-normality and allows one to address different types of nonlinearities in the data such as asymmetry and heavy tails.

The purpose of this paper is to improve the operation and maintenance intelligence of power systems, and summarize the transmission line robots and their key technologies. High-voltage power cables are important channels for power transmission systems. Their special geographical environment and harsh natural environment can lead to many different faults. At present, such special operations in dangerous and harsh environments are performed manually, which have not only high labor intensity and low work efficiency but also great personal safety risks.

For maintenance works that are far away from the tower, power outages are required. With the increasing evaluation of transmission quality and operational safety, and the urgent need for automation and operation of modern power systems, the contradiction between this manual operation and modern high-quality power transmission has become increasingly prominent. An effective method to replace the manual maintenance work is to use the mobile robot to carry the operation manipulator and its end tool, that is, the live maintenance robot.

Some achievements have been made in the key technologies of live maintenance robots, the work to be done to meet the basic requirements of complex and changeable line environment and practical application. Based on the existing research results of live overhaul robot, the follow-up research will focus on the practical application needs and the frontier of scientific and technological development, and truly realize the human–machine integration between live overhaul robot–human working environment. Only in this way can the robot better serve the operation and maintenance of the power system.

This paper reviews the system platform, operation function, structural characteristics and key technologies involved in the power cable robot, and the combination of live maintenance robots and modern high-tech such as big data and cloud computing is also given, and finally, the future development direction of the special operation robot is pointed out.

The purpose of this paper is to present a method to calculate the transient induced voltages along the underground pipelines and analyze the transient interference generated in the pipelines due to the inductive coupling in the fault‐to‐ground condition of power lines in close proximity.

Based on finite difference‐time domain method, an improved method is proposed to calculate transient inductive interference in underground metallic pipelines due to a fault in nearby power lines. The frequency‐dependent problem in the analysis of transient interference is solved in phase domain. Compared with the traditional method, the disposal of phase‐modal transformation matrices’ frequency‐dependent characteristic is avoided and the calculation is simplified by using vector fitting approach and recursive algorithm greatly in the proposed method.

A novel improved method is proposed to calculate transient induced voltage distribution along underground metallic pipelines due to a fault in nearby power lines. Results show that the peak value of transient induced voltage at the most critical point is about 1.15 times of the magnitude in the steady state without the fault removed and the analysis of transient inductive interference is necessary in the fault‐to‐ground case of power lines.

In order to mitigate the interference from power lines to nearby pipelines, pipelines should be good grounded and positioned as far away from the power line as possible. In high soil resistivity areas, the common corridor should be avoided.

The paper presents a method to calculate the transient induced voltages along the underground pipelines and analyze the transient interference generated in the pipelines due to the inductive coupling in the fault‐to‐ground condition of nearby power lines. The proposed method is general and can also be applied to other transient interference studies such as crosstalk problems of communication networks and interference between power lines and aboveground pipelines or communication cables. Effects of various parameters upon the inductive interference generated in underground pipelines due to a fault in nearby power lines are analyzed to be a guide for controlling the inductive interference.

This study aims to examine the moderation role of human resource management (HRM) in the relationship between risk management and project success of electrical power transmission and distribution systems.

A questionnaire was used to collect data from the electrical companies of Pakistan. A 100 professionals working in power sector companies took part in it. To analyze the impact, correlation analysis and linear regression analyses have been performed using IBM SPSS V-22®.

The linear regression results obtained the significant impact of risk management on project success (p < 0.05). The moderated regression represented a change in the percentage variation (R²) that is 0.463 without moderating effect and it increased to 0.528 after including human resource (HR) moderator indicating a moderating effect of HRM.

Because of the theoretical significance of growing awareness about the importance of HRM and development, this study has significant practical implications. This study can be implemented practically to support the business strategies of the organization and HR competency and engineering will contribute in shaping those business strategies as well.

This study provides evidence on the impact of HRM on project success as a moderating variable with risk management. The study shows the increment in the ratio of project success in the electrical sector of Pakistan. This research provides the importance of HRM functions in the electrical sector of Pakistan.