Electric Power Substations Research Articles

Improving reliability of porcelain post insulators at electric power Substations

At electric power substations, post insulators are designed for isolation and fastening of conductive parts of electrical installations. Insulators are installed on outdoor switchgear of substations as part of the main switching equipment. During operation, they are exposed to external atmospheric effects, mechanical and dynamic loads. Timely replacement of post insulators increases significantly the reliability of the main substation equipment at power substations. The question of improving reliability at transformer and traction substations is considered, external and internal factors associated with destruction of porcelain post insulators (PPI) are presented. It is established that the main cause of damage to PPI are sharp changes in ambient temperature, especially the transition of temperature values through 0°C. A model of a porcelain post insulator with an insulating body of elliptic shape is proposed. Operation of the proposed device is described. Analysis is presented of the ratio of the lengths of the axes of a circle and ellipse (major-to-minor) as related to spatial positioning in power loads. It has been determined by calculation that a post insulator should be installed in such a way that the major axis of the ellipse be aligned in the direction of the temperature gradient — sunlight, to reduce the impact of heating on the minor axis of the insulator.

Fusion of Infrared-Visible Images in UE-IoT for Fault Point Detection Based on GAN

In the development of modern intelligent Ubiquitous Electric Internet of Things (UE-IoT), infrared thermal imaging always plays an important role in automated early-warning detection of developing failures of critical assets such as transformers, disconnects and capacity banks in electrical power substation non-intrusively. However, the low resolution and contrast of infrared images hinder the subsequent analysis and recognition of fault points. In contrast, visible images present abundant texture details of the equipment without thermal information. In order to assist the detection of fault points, this paper proposes a Generative adversarial networks (GAN) based infrared and visible image fusion method to produce a composite image with enhanced edges and better quality. The edge loss function is added to represent the perceptual edges. In the discriminator, the proposed method improves the texture similarity between fusion image and visible image by minimizing the Wasserstein distance in VGG (Visual Geometry Group network) feature space. The experimental results show that the fault regions become more salient and the details are enhanced. In this way, it can facilitate the detection of fault points both reliably and accurately.

Dissolved Gas Analysis Equipment for Online Monitoring of Transformer Oil: A Review.

Power transformers are the most important assets of electric power substations. The reliability in the operation of electric power transmission and distribution is due to the correct operation and maintenance of power transformers. The parameters that are most used to assess the health status of power transformers are dissolved gas analysis (DGA), oil quality analysis (OQA) and content of furfuraldehydes (FFA) in oil. The parameter that currently allows for simple online monitoring in an energized transformer is the DGA. Although most of the DGA continues to be done in the laboratory, the trend is online DGA monitoring, since it allows for detection or diagnosis of the faults throughout the life of the power transformers. This study presents a review of the main DGA monitors, single- or multi-gas, their most important specifications, accuracy, repeatability and measurement range, the types of installation, valve or closed loop, and number of analogue inputs and outputs. This review shows the differences between the main existing DGA monitors and aims to help in the selection of the most suitable DGA monitoring approach according to the needs of each case.

Grounding grid design in electrical power substation using optimization methods

A good substation grounding grid is essential to ensure safety of personnel working in the substation, and also to protect the equipment to ensure continuous operation of the substation. The design of the substation grounding grid is often carried out to meet the IEEE Std 80-2000 requirements of grounding resistance, touch voltage and step voltage at an economical cost. However, the conventional grounding grid design is normally over calculated to meets these IEEE requirements without considering the total cost. The grounding grid is often costly to implement due to high number of grounding conductors and rods, and large area size of the interconnected bare conductors. In this study, Gravitational Search Algorithm (GSA) and Particle Swarm Algorithm (PSO) are proposed to achieve an effective grounding grid calculation. The reliability of these algorithms has been validated using a typical medium voltage substation grounding grid parameters. It was found both that GSA and PSO were capable to achieve a lower cost with of grounding grid with 29% cost saving as compared to the conventional calculation technique, without compromising the safety requirements of grounding grid.

Risk management during construction of electric power substations

Abstract The construction of electric power substations poses a great number of risks due to its dangerous environment. The objective of this work was to evaluate the perception of construction workers on risks, methods they use for evaluation and managing risks to which they are exposed. This study carried out a qualitative and quantitative analysis during the expansion of one electric substation, adding an additional 100 MVA power transformer. The risks were identified and analysed by using the Preliminary Risk Analysis (PRA). Additionally, a questionnaire on construction safety was created and applied on all 27 workers which participated in the construction. The results showed which activities are present during the construction of a power substation, which risks are involved and how to manage them. It was found that among several, the PRA and Checklists were the most commonly used analysis tools. Further on, it was found a relation between training and risk perception. Among perceived risks were: noise, working at heights, electric shocks, traffic accidents, poisonous animals, dust, fire and explosions. The conclusion of this study was that the construction of electric power substations brings several safety risks and that the instruction of workers allows an effective risk management, and can reduce the number of accidents in this type of working activity.

FARIMA model‐based communication traffic anomaly detection in intelligent electric power substations

The technological advances of intelligent electric substations have significantly improved the operational performance of power utilities by incorporating advanced monitoring and control functionalities. The data traffic patterns in substation communication network (SCN) need to be better understood to improve the SCN performance against different forms of cyber-attacks. To this end, this study presents a fractional auto-regressive integrated moving average (FARIMA)-based threshold model to characterise the SCN traffic flow based on the IEC 61850 protocol and carry out anomaly detection. The performance of the proposed anomaly detection solution is assessed and validated through numerical analysis under the condition of the cyber storm based on the collected SCN data traffic from a real 110 kV substation, and the numerical results clearly confirmed its effectiveness.

Availability analysis of power substation automation architectures with PRP and HSR protocols

Industrial automation has been widely used in electric power substations. In this context, the IEC 61850 standard provides for the utilisation of redundancy in the data link layer to increase frame reception probability. This study aims to evaluate the availability of two power substation automation architectures based on the IEC 62439-3 standard, which describes two redundancy protocols named parallel redundancy protocol (PRP) and high-availability seamless redundancy (HSR). The authors evaluate both architectures using either PRP or HSR protocol against using no redundancy protocols. The reliability block diagram method has been used, and afterwards, the mean time to failure and availability have been calculated. Results show that the utilisation of redundancy protocols allied to the repair during the mission allows classifying the architectures in the higher availability class according to CEI IEC 870-4.

Development of an improved earthing method for power and distribution transformers substations

Engineers and planners have realized that equipment grounding is a necessary part of installation process in Electrical power substations. Over years, grounding or earthing has been carried out primarily through preparation of Earth Mat which is interconnected with several Earth-rods buried around the equipment under consideration. This approach takes several efforts to have an acceptable and reliable result. However, this paper presents a more flexible, economical and results oriented approach. A flow chart which describes the procedures of carrying out the proposed method of earthing is developed. This was applied to two case studies: a proposed Power transformer substation and distribution Transformer substation located within the same geographical domain. On the two cases, the measured earth resistances are presented and discussed. The results from the case study indicates that the earth resistance values obtained from this new approach are reliable and in compliance with IEEE Standards 80,142, 81 and 1100. Keywords : Equipment, Grounding, Earthing, Earth-rod, Flowchart, Earth Mat, Flow Process, Injection Substation, Distribution Substation, Earth Resistance, IEEE Standard.

Methodology for Determining Reliability Indices of Electric Power Substations

This work proposes a new methodology for reliability/availability analysis in power substations. The proposed methodology is based on a combination of Fault Tree Analysis and Monte Carlo Simulations, which are typically used separately in reliability analysis. Results show that vulnerable points can be identified in the substation under analysis, thus providing a useful support when deciding about preventive maintenance schedule or investment direction. The solution here presented is compared to a conventional reliability analysis based on series-parallel networks connection, which allows to verify the effectiveness of this new approach.

Structural performance of cold-formed steel trusses used in electric power substations

This paper presents a detailed investigation of the lateral characteristics of cold-formed steel truss structures used in electric power substations. Five full-scale specimens were tested, and their responses were recorded under monotonic and cyclic loading regimes. Of particular interest were the specimens' maximum lateral load capacities and deformation behaviours. A rational estimation of the seismic response modification factor, R, of the truss structures is also provided. In addition, different types of stiffened sections were employed in order to examine the impact of the presence of stiffeners and lips on seismic behaviour, as well as on the lateral resistance of the structure. Detailed comparisons between relevant code methods, finite element modelling and an experimental study were then conducted to suggest an appropriate value for the R factor. A financial evaluation was also performed, to highlight the advantages of employing cold-formed steel trusses in the electric power substation industry. The results show that the cold-formed steel structural system is a reasonable alternative to the currently used hot-rolled steel structures, and that its use decreases the cost of the structures by almost 50%.

The calculations of conductive noise and heating of the screen in a control cable

Lighting strokes and short circuits (SCs) are the main sources of conductive noise that propagates along control cables and can lead to the failure of microprocessor equipment in the protection and control systems of electric power substations. Two-sided grounding of the screen of a control cable substantially reduces the pulse and high-frequency conductive noise level, but leads to heating of the screen under short-circuit conditions. The existing standards determine the conductive noise and screen heating as a function of screen voltage that is suitable for a single cable. A more general case that takes into account the cable magnetic coupling with other conductors when current is used as a calculation parameter has been considered. The conductive noise at the first pulse of lightning current is determined using the transfer impedance “screen–cable core” or 3D cable model in the general case. To calculate the heating, the formula of GOST (State Standard) 28895-91, which is rejected in modern standards because of the assumption that short-circuit current is invariable (in fact, the current decreases with heating of the screen), has been used. Using this formula in a step algorithm leads to correct results. The cable magnetic coupling with other conductors is expressed as insertion impedance that increases the screen impedance and decreases the current and screen heating. A numerical experiment for a typical cable has shown that conductive noise and heating of the screen of the cable can be substantially reduced because of the parallel laying of conductors. It has been concluded that, to decrease the conductive noise and heating of the screen of a control cable, it is necessary to decrease the screen current.

Hybrid system of power factor correction

The paper reviews research data of hybrid of reactive power compensation for Metro electric power substations. Comparative compensation analysis has been made and the control system for the suggested device has been developed; besides, mathematic simulation has been carried out, as a result of which the power factor of substation has been increased from 0.5 to 0.97-0.99.

Investigate and Analyze the Electromagnetic Field Levels Inside Electric Power Substation

Investigate and Analyze the Electromagnetic Field Levels Inside Electric Power Substation

Investigate and Analyze the Electromagnetic Field Levels Inside an Electric Power Substation

The electric power transformers are very important part of the modern electric power and transmission line network systems. They are a high level source of the electromagnetic fields which can effect the workers health in the station. In this research, an electric and magnetic fields are generated due to the operation of the substation power distribution of 132/33 kV that investigated in order to avoid the workers overexposure these fields workers. This research has two phases a mathematical calculations and practical measurements. The intensities of the electric and magnetic fields have been measured at a substation using EMF tester device. The safe zones around the dangerous equipment have been determined. A comparison between the obtained results and the standard safety guideline limits has been done and the comparison results shows that they are within the acceptable limits.

Semi-automatic methodology for augmented panorama development in industrial outdoor environments

The use of virtual reality (VR) environments based on augmented panoramas enables the creation of visualization scenarios in different application areas. These panorama-based environments significantly reduce the cost and the timeframe of developing VR applications. The use of this visualization modality in industrial environments is appropriate because in these scenarios there is little or no change of the viewable physical environment during long periods of operation. The combined use of VR concepts and augmented reality (AR) enables the creation of applications that use object detection based on image characteristics and the inclusion of information through an augmented environment. With this in mind, this paper presents a methodology for creating VR environments based on augmented panoramas that uses semi-automatic object detection using Haar-like features and real images of the operating environment. The methodology was used to create an augmented environment based on an electric power substation as a case study. This environment is used for visualizing power substation equipment variables, and it shows the possibilities of using several panorama formats for the visualization.

Study on a Harmonic Measurement and Analysis Method for Power Supply System

Abstract In the power supply system of high speed railway, the generated harmonics can not only influence the electric energy quality of power system, occur the voltage fluctuation and flicker, and affect the service life of traction equipment and traction transformer of electric power substation, but also cause the secondary protection misoperation of automatic control system, and affect the normal operation of the train. With the increase of overhead contact line transmission, the generated harmonics increased the communication interference. Therefore, on the basis of analyzing the generation and spectrum of harmonics in power system, an improved S transform method is introduced in order to propose a harmonic measurement and analysis method based on improved S transform for power supply system of high speed railway in this paper. The proposed method can effectively realize the harmonic measurement and analysis of power supply system. In order to testify the effectiveness of the proposed harmonic measurement and analysis method, Yingkou substation of Harbin-Dalian high speed railway is selected in here. The actual analysis calculation and experiment results show that the proposed method can effectively measure and analyze the harmonic in the power supply system of high speed railway. It provides a theoretical basis for solving the practical engineering problem of power supply.

On the Modeling and Analysis of Communication Traffic in Intelligent Electric Power Substations

The underlying substation communication network (SCN) is of paramount importance in facilitating the advanced functionalities of substation automation. To design and maintain an efficient SCN to guarantee high transmission availability and information integrity, an accurate traffic model is required and the traffic characteristics need to be understood. This paper exploits the challenge of modeling and analyzing SCN data traffic from the data generating mechanism to the transmission and retransmission mechanisms, and reveals the symbiosis of short-range dependence and self-similarity. Recognizing that there is little research effort available, this paper proposes a viable approach in modeling the SCN traffic and mathematically analyzes the associated parameters aiming to accurately model the self-similarity behavior of SCN traffic, describes the symbiotic characteristics, and effectively predicts the traffic pattern. Further, the proposed modeling approach is validated and assessed through a case study by using a realistic 24-h dataset collected from a 110 kV substation's supervisory-control-and-data-acquisition system. The result clearly demonstrates that the model can accurately describe and forecast the SCN traffic with the autocorrelation function mean square error as small as $\mathrm{MSE}\left(\mathrm{m}\right)=2.077\times {10}^{-3}$ . The insights obtained from this work can significantly promote the design and operation of SCNs.

STUDY OF KEY DESIGN PARAMETERS OF DIFFERENTIAL-PHASE PROTECTION OF BUSBARS OF POWER FACILITIES AND FACTORS OF ELECTRICAL NETWORKS AFFECTING THEIR CHOICE

The article deals with questions concerning to the main design parameters of differential-phase busbar protection switchgear with voltage 110–750 Kv of electric power stations and substations, the choice of which is provided by its selective and reliable operation in all possible power system conditions. Article contains the block diagram and operating characteristic of protection. The factors that have a direct impact on the determination error by the reacting body to protect the relationship between the phases of the currents circulating connections that are connected to the busbar system are determined. The influence degree of these factors as well as possible ways to tune away from its impact protection are given. Possibility of the differential-phase principle application for busbars protection on the basis of conditions for ensuring its sufficient sensitivity and selectivity in normal mode was analysed, when the external short circuit on the connections of the busbars and for faults in the protection zone of action. Guided by the assumptions made in carrying out an approximate calculation of the angular errors of the current transformers in the power system transient modes the characteristic which allows to set the dependence of the values of these errors on the lifetime of the transitional process in the electrical network is built

Mobile robot for power substation inspection: a survey

This paper presents the most important achievements in the field of electric power substation equipment's inspection by mobile robot. To accelerate the realization of unattended substation, which would improve the reliability, safety and intelligence of power substation, the field of automated power substation equipment's inspection has been greatly developed over the last decade. The paper addresses the power substation inspection robot, which is considered as one of the most active fields of research on mobile robot, from its history to design requirements, the robot system architecture analysis and modeling, reliability technology of the robot, autonomy and universality of substation equipment inspection. Besides, summaries and suggestions on the development and research trend of inspection robot, which should be addressed in the future, are given. The present work may serve as reference for initial design of robots for some complex and dangerous working environments. And some unique insights for the inspection robot provided in this paper may be of help to further research and application of power facilities inspection.

A MODEL‐BASED SYSTEMS ENGINEERING APPROACH TO RESILIENCY ANALYSIS OF AN ELECTRICAL DISTRIBUTION FACILITY

ABSTRACTThis article describes a model‐based systems engineering (MBSE) approach to cyberattack resilience modeling for an electrical power substation and demonstrates that (1) resiliency can be quantitatively characterized to enable design tradeoffs and (2) the analysis can be incorporated into a Systems Modeling Language (SysML) model to enable it to be incorporated into an MBSE development effort. The resiliency analytical model described here using the Markov model, derives from previous work on survivability analysis. For the system under analysis, it showed that the most important performance parameter for cyber resilience is propagation resistance followed by an attack rate mitigation. However, this applicability of this result is limited to this particular system with the parameter values described below. What is of more general importance is the value of such modeling, that when combined with SysML parametric analysis capability and the differential equation solvers in tools such as Matlab, has promise in improving resiliency with respect to cyber threats in the national energy.