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Resilience of High Voltage Transmission System

Resilience of High Voltage Transmission System

The resilience of a system can be achieved by reducing its probability of failure as well as reducing the con- sequences from such failures and the time to recovery. Quantification of resilience is first approached from the broader societal context, from which the engineering sub-problem is formulated as an important building block of the integrated tool ultimately needed. Nonlinear structural responses are considered, as well as the impact of retrofit or repair. Impact on time to recovery is considered in all cases. The proposed framework makes it possible to relate probability functions, fragilities, and resilience in a single integrated approach, and to further develop general tools to quantify resilience. The high voltage transmission system is typical engineering system which requires the assessment of the resilience as the measure for evaluation of the po- tential hazard event development. In this respect the resilience of the high voltage transport system is highly vulnerable: central generation creates high value targets, long vulnerable transmission lines, unique high voltage transformers, vulnerable substations. The assessment of the resilience of the high voltage transmis- sion system is based on the evaluation of the resilience index as the result of the sudden changes of the char- acteristic indicators.
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1. ELECTRICAL SYSTEM

1. ELECTRICAL SYSTEM

service. The transmission and distribution network include sub-stations, lines and distribution transformers. High voltage transmission is used so that smaller, more economical wire sizes can be employed to carry the lower current and to reduce losses. Sub-stations, containing step-down transformers, reduce the voltage for distribution to industrial users. The voltage is further reduced for commercial facilities. Electricity must be generated, as and when it is needed since electricity cannot be stored virtually in the system.
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Cost Effective Design of Extra High Voltage Transmission Lines for Minimizing Transmission Congestion Problems

Cost Effective Design of Extra High Voltage Transmission Lines for Minimizing Transmission Congestion Problems

all these fields in vicinity of overhead transmission lines is an obvious feature in transmission line design procedure. Increasing transmission line voltages are found to have effects related to health on human being and other living objects in its neighborhood [4]. Sufficient Transmission corridor width throughout the length of transmission line is the foremost requirement. Right of way is provided to confine immediate hazards due to Electric fields and long term health related issues due to Magnetic Field (EMF) on occupants [5]. Required corridor width for a transmission line is decided by peak value of electric field, dB value of audible noise, radio interference and magnitude of magnetic field in its surrounding area due to flow of power in the line. All the non-ionizing fields and corona effects must have their effective values within limits as specified in standards [5-7]. Major factors affecting Electric field strength are Voltage rating, Phase to Phase Distance, Conductor height above the ground, No. of sub conductors and conductor cross section area. Magnetic fields mostly are affected by current flowing through the line. Electromagnetic field and Corona effects near ground surface throughout the transmission corridor need to be plotted for analysis and minimization purpose. Fields values are measured at 2 meter height from ground level which is average human height and also on the edge of ROW the values are measured. Values of field effects and corona should be less than maximum permissible values within entire corridor width.
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High Voltage Direct Current Transmission

High Voltage Direct Current Transmission

During the planning stage of a HVDC project, prelimi- nary studies are carried out in order to establish the basic design of the whole HVDC transmission project. This includes the co-ordination of all relevant technical parts of the transmission system like HVDC converters, AC and DC overhead lines as well as the submarine cable, if applicable. All specified requirements will be taken into account and are the basis for the preliminary design of the HVDC transmission link. In addition, special attention is paid to improving the stability of both connected AC systems. Several additional control functions like power modulation, frequency control and AC voltage limiter can be included in order to provide excellent dynamic behaviour and to assist the AC systems if the studies show it necessary. Sub- synchronous oscillation will be avoided by special control functions, if required. All the AC system con- ditions and the environmental conditions as given in the relevant documents will be considered in the design calculations. The final design of the HVDC transmission system, including the operation charac- teristics, will be defined during the detailed system studies. All necessary studies are carried out to confirm the appropriate performance requirements and ratings of all the equipment. Due consideration is given to the interaction with the AC systems on both sides, the generation of reactive power, system frequency variations, overvoltages, short circuit levels and system inertia during all system configurations.
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Robot for High Voltage Transmission Line Inspection

Robot for High Voltage Transmission Line Inspection

In HSV, it is easier to represent a color than RGB color- space. So, image is converted from BGR color space (the default one) to HSV color space. There are many color-space conversion methods available in OpenCV. For color conversion, function used is cv2.cvtColor (input image, flag), where flag determines the type of conversion. For BGR to HSV, we use the flag cv2.COLOR_BGR2HSV. After converting the image in HSV format, we can use this to extract a colored object. So, the object in our case is the corroded transmission line and in order to detect it, while specifying the range of color, we have specified the range of brownish color (like corrosion) by trial and error method.
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Environmental Impacts of Electromagnetic Radiation Inducted by High Voltage-Power Lines

Environmental Impacts of Electromagnetic Radiation Inducted by High Voltage-Power Lines

The possible effect of e lectric current upon the growth of plants has been the object of various types of research for more than 150 years. In recent years many phases of this problem have been studied by English, French, Finnish, German and A me rican observers and scientists . A number of the m have reported apparent significant increases in crop yields resulting fro m treat ment with electric current; others have found little or no difference. A mong these later t ria ls, which, in most instances, appear to have been conducted und er carefully controlled conditions, the majo rity show significant yie ld increases for the e lectrical treat ment. In the few e xpe riments where the e ffect of e lectric current upon the physiologic functions of plants has been investigated, the results obtaine d have failed to provide a satisfactory e xplanation for y ield d ifferences, therefore, fie ld study of high voltage on natural vegetation is highly required. Most of the recent studies focus on the growth of plants and the germination of their seeds.According to some studies these fie lds e xerts beneficia l effects as it increases rate of growth and early germination of seeds (Flo rezet al., 2004; Dardenizet al., 2006; Liang et al., 2009). On the other hand, some studies suggested harmful effects like inhibit io n of growth and seed germination (Apashevaet al., 2006; Ahmad et al., 2007). In fact, EM F causes an oxidative stress that increases the activity, concentration and lifetime of free radica ls (Tka lec et al., 2005). EMF a lters protein b iosynthesis, enzy me activ ity, ce ll reproduction and cellula r metabolis m (Nirma la and Rao, 1996). Exposure to EMF leads to cell death as a result of increase in free o xygen rad icals and DNA da mage (Ivancsits et al., 2003). Several studies have been conducted to find out the effect of EM F on the growth and physiology of the plants (Yao et al., 2006; Shabrangi and Majd, 2009), such as studying effects of EMF on seeds germination and seedlings growth and seed vigor (Moon and Chung, 2000 and Ph irkeetal., 1996).
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Stability Assessment of Pipeline Cathodic Protection Potentials Under the Influence of AC Interference

Stability Assessment of Pipeline Cathodic Protection Potentials Under the Influence of AC Interference

Abstract—Metallic pipelines are protected from induced corrosion by the application of coating and Cathodic Protection (CP) systems. The latter is achieved by keeping the pipeline at a constant Direct Current (DC) voltage in relation to the surrounding soil. While this is conventionally meant to arrest corrosion, the Alternating Current (AC) interference from high voltage transmission lines has been a major problem to the CP potential systems of buried steel pipelines. Several research studies dealing with this problem have been published, and a lot of research work is still on going. This work focuses on assessing the stability of the CP potentials under the influence of AC interference. Seven different CP potentials varying from −800 mV to −1200 mV were applied on steel pipe specimen exposed to the AC interference with a varying AC voltage from 0–50 V. The results of the laboratory investigation revealed that CP potential of − 1150 mV was more stable under the influence of AC interference, with just a minimal shift from the set value. The results from the corrosion morphology tests on the pipelines using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) reveal the need for optimising the CP potential to provide adequate or optimum protection to the pipelines. Thus, more research studies involving simulation and field studies may lead to a major breakthrough in improving protection potentials.
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STUDY OF TRANSMISSION LINES EFFECT ON THE SYSTEM OPERATIONON OF CONTINUOUS AUTOMATIC CAB SIGNALLING

STUDY OF TRANSMISSION LINES EFFECT ON THE SYSTEM OPERATIONON OF CONTINUOUS AUTOMATIC CAB SIGNALLING

Purpose. To conduct an effect research of the electromagnetic field of high-voltage transmission lines (HVTL) (750 kV, 50 Hz) on the track circuits and continuous automatic cab signalling (CACS) with a signal current of 50 Hz in the areas of convergence and intersection with the transmission lines and to propose possible methods to improve noise immunity of CACS. Methodology. The measurements were performed both by means of car-laboratory and directly on rail lines. During the study the electric field strength in the range of industrial frequency directly under the transmis- sion lines and at the distance from it to the railway lines was measured, as well as the time dependence of CACS codes with signal current frequency of 50 Hz directly under the transmission lines and at a distance from it in the absence of the train and its passing. Findings. The root causes analysis of CACS faults and failures was carried out. The effect of the electromagnetic field of high-voltage transmission lines (750 kV, 50 Hz) on the track circuit and CACS with signal current of 50 Hz in the areas of convergence and intersection with the transmission line was investigated. Possible methods to improve noise immunity of CACS were considered. Originality. The effect research of transmission lines (750 kV) on the operation of the automatic cab signalling on spans Prishib-Burchatsk and Privolnoye-Yelizarovo, Prid- neprovsk railway in places of oblique railroads crossing and transmission lines (750 kV, 50 Hz) was conducted. Elec- tric field strength in the range of industrial frequency directly under the transmission lines and at a distance from it to the railway line, as well as the time dependences of ALSN codes with signal current frequency of 50 Hz directly under the transmission lines and at a distance from it in the absence of the train and as its passing were measured. It was found that CACS codes in track circuits under transmission lines are strongly distorted, as strength measurements of electric field are shown, it can be explained by the electromagnetic field effect of transmission lines on track circuits. Practical value. Possible methods of CACS safety enhancement by improving the reliability of signaling from a track on the locomotive were considered.
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Networks of high frequency inhomogeneous transmission lines

Networks of high frequency inhomogeneous transmission lines

Abstract. It is well known from classical transmission line theory, that transmission lines can be folded into impedances and thereby used in an electrical network setting. But it is also possible to create large networks of transmission lines consisting of tubes and junctions. The tubes contain the trans- mission lines and the junctions consider the mutual influ- ences of the adjacent tubes or the terminals. The calculation of the currents and voltages at the junctions can be performed with the help the BLT-equation. So far this method is not ap- plicable for nonuniform transmission lines described in a full wave method, because the lack of a distinct voltage gives no possibility for junctions. Junctions only make sense, when the considered network offers the possibility to propagate a TEM-Mode. If this requirement is fullfilled, nonuniform transmission lines could be included in an electrical network. This approach is validated in this paper in form of numerical simulations as well as measurements.
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Issues on High Speed Relaying in High Voltage Transmission lines using Full Cycle Discrete Fourier Transform and Phaselet Transform

Issues on High Speed Relaying in High Voltage Transmission lines using Full Cycle Discrete Fourier Transform and Phaselet Transform

In [12],[13],a new approach for computation of Fourier transform using phaselets has been introduced and applied in transmission line differential relay. This improved the operating time of the relay. But phaselets are initiated only after the fault has been triggered. The fault has to be sensed by the relay or by some fault sensing algorithms in order to initiate the phaselet. This sensing time should also be considered while evaluating the performance of this new approach.

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Rental Value Around HVOTL Facilities in Residential Neighborhoods of Metropolitan Lagos,Nigeria

Rental Value Around HVOTL Facilities in Residential Neighborhoods of Metropolitan Lagos,Nigeria

For instance, a study conducted by Hamilton and Caruthers (1993) on the effects of transmission lines on property values in Vancouver, British Colombia. The authors analysed a six year property market data and found a diminution value of 5% on property proximal to power lines by 120 meters. A further study by Hamilton and Schwann (1995) surveyed 12,907 residential dwellings within four neighbourhoods in Vancouver, British Colombia within a period of 6 years (1985-1991). The result of the duo found a 6.3% diminution effect on properties located 100 meters to a 230Kv power lines and a 1.1% diminution effect on properties 200 meters from another 500Kv power lines. Complete removal of the pylon and power lines increased value by a 6.3% margin. Rosiers (1998), agreed with the findings of Colwell (1990) which portrayed a diminution in property values as a result of the visual effects of pylons and power lines. After a survey carried out on 507 single family sales, analysis showed a lesser diminution value on a property physically closer to a HVOTL but with its glare shielded by a wood, unlike other less proximal properties which had the direct glare of the power lines unshielded.
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Power transmission line fault location based on current traveling waves

Power transmission line fault location based on current traveling waves

the ‘mother wavelet’. Wavelets are functions that satisfy the requirements of both time and fre- quency localization. The necessary and sufficient condition for wavelets is that it must be oscil- latory, must decay quickly to zero and must have an average value of zero. In addition, for the discrete wavelet transform considered here, the wavelets are orthogonal to each other. Wavelet has a digitally implementable counterpart called the discrete wavelet transform (DWT). The generated waveforms are analyzed with wavelet multiresolution analysis to extract sub-band information from the simulated transients. Daubechies wavelets are commonly used in the analysis of traveling waves [118]. They were found to be closely matched to the processed signal, which is of utmost importance in wavelet applications. Daubechies wavelets are more localized i.e., compactly supported in time and hence are good for short and fast transient analysis and provide almost perfect reconstruction. However, there are some other wavelets show a good correlation with the transient signals and may be used in the analysis. Several wavelets have been used in this thesis. The comparison is presented in section (3.3.4). Due to the unique feature of providing multiple resolution in both time and frequency by wavelets, the sub-band information can be extracted from the original signal. When applied to faults, these sub-band information are seen to provide useful signatures of transmission line faults, so that the fault location can be done more accurately. By randomly shifting the point of fault on the transmission line, a number of simulations are carried out employing the ATP/EMTP. The generated time domain signals for each case are transferred to the modal domain using Clark’s transformation. Then, the aerial mode signal is analyzed using wavelet transform. From the different decomposed levels, only one level is considered for the analysis. This level has the highest energy level output and the dominant frequency of the transient.
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Impulse Breakdown Characteristics of Main Gap in the Presence of a Local Discharge

Impulse Breakdown Characteristics of Main Gap in the Presence of a Local Discharge

The characteristics of impulse breakdown voltages and the influence of the position of third electrode in air gap are investigated experimentally to study the parameters influencing the breakdown voltage in the presence of metallic objects around the high voltage power apparatus with air insulation. Experimental results show that the factors affecting the breakdown voltage are the shape and the size of the grounded electrode, the third metallic electrode location and the gap length. A comparison between negative and positive polarities of the applied voltages indicates an important influence of the polarity in the dielectric breakdown mechanism. The possible mechanism by which the local electric discharge initiates the main dielectric breakdown seems to be the high electric field around the local discharge channel and the streamers protruding from its surface.
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Contingency Analysis in 14-Bus Power System with TCSC

Contingency Analysis in 14-Bus Power System with TCSC

The Line Outage Distribution Factor (LODF) is one of the important linear sensitivity factors which play a key role in result the effect of the critical contingencies and hence suggesting possible preventive and corrective actions to solve the violations in the system. LODFs are used to approximate change in the flow on one line caused by the outage of a second line. Typically they are only used to determine the change in the MW flow compared to the pre contingency flow. Flexible Alternating Current Transmission Systems are inject in transmission lines so to minimize the problems and FACTS used for control of voltage, phaseangle andimpedance of highvoltage transmission lines.The strategic benefitsof incorporating FACTS devices are improved reliability, better utilization of existing transmission system,improvedavailability,increased transientanddynamicstability and increased quality of supply Thyristor Controlled Switching Compensator (TCSC) is connected in series with transmission lines and which transport not intermittent and variable control of line impedance with much faster response compared to conventional control devices. To determine the suitable location for FACTS devices a loss sensitivity method is used.
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Improving the Performance of a Real High Voltage Network in the Casablanca Region

Improving the Performance of a Real High Voltage Network in the Casablanca Region

on the transport line which compensates for the inductive voltage drop. They also modify the effective reactance of the line. The inserted voltage is proportional and perpendicular to the current flowing in the line. Types of series FACTS are TCSC (Thyristor Controlled Series Capacitors) and SSSC (Static Synchronous Series Compensator)

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Recovery of Oregon Coast Coho Salmon (Onchorhynchus kitsutch) through Restoration of Freshwater Habitats

Recovery of Oregon Coast Coho Salmon (Onchorhynchus kitsutch) through Restoration of Freshwater Habitats

In addition to causing outages, vegetation can also result in fires, which can damage land and property. If arcing or direct contact between vegetation and electricity occur parts of the tree or plant can fall to the ground and cause wildfires. Cal Fire estimates that 1 to 3% of wildfires in California are the result of vegetation conflicts with power lines (Mitchell, 2009). The potential for fire can be especially worrisome during years of drought. Trees become stressed when there is not enough water and can become susceptible to disease and insect infestation. Combined, this can lead to widespread tree decline and death. Dead and dying trees can then drop branches on, or fall into electrical facilities, leading to downed wires, broken equipment, and fire. Electric transmission lines run through very remote forested areas of the state. If a fire were to start it could cause significant damage before it is discovered and addressed (Mitchell, 2009).
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A Literature Survey on Artificial Neural Network for Fault Detection of HVDC Transmission

A Literature Survey on Artificial Neural Network for Fault Detection of HVDC Transmission

the faults in converter can be detected [33]. The faults such as valve short circuit, misfire and arc through faults are d iscussed in this paper. With the help of ANN and wavelet transformation, the fau lt is easily classified and detected respectively. Wavelet analysis expands functions not in terms of trigonometric polynomials but in terms of wavelets, which are generated in the form of translations and dilations of a fixed function called the mother wavelet. Co mpared with Fourier transform, wavelet can obtain both time and frequency information of signal, while only frequency information can be obtained by Fourier transform. Each wavelet is created by scaling and translation operations in a special function called mother wavelet. A mother wavelet is a function that oscillates, has finite energy and zero mean value [32]. When fault occurs on a DC line, the travelling waves propagate along the line and are reflected at discontinuous points of surge impedance. This leads to an abrupt change in the voltage and current and hence in the reverse voltage travelling wave. The sudden changes are the edges in signal processing. The wavelet theory is used to detect the sudden changes, and the fault location can be identified along with the recognition of the fault by obtaining the time delay ∆t in seconds between the two absolute maximu m values of the wavelet coefficients. By denoting
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Outages On Nigerian Integrated High Voltage Transmission Grid

Outages On Nigerian Integrated High Voltage Transmission Grid

The high voltage transmission in Nigeria is separated into two; the 330KV high voltage transmission and the 132KV high voltage transmission. The 330KV transmission is from the generating stations to the sub-transmission system. The sub-transmission system which works at 132KV is the National Control Centre (NCC) which is at Oshogbo. This 132KV system disseminates voltages at diverse levels relying upon the kind of dissemination example. These voltages are 33KV, 11KV and 415/240V distribution levels [Ibe .A.O. and Okedu .E.K, 2009].
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STATCOM Device to Regulate PF of Grid Using Multi-Level Inverter

STATCOM Device to Regulate PF of Grid Using Multi-Level Inverter

A new multilevel voltage-source inverter with separate DC sources is proposed for high-voltage, high power applications, such as flexible AC transmission systems (FACTS) including static VAr generation (SVG), power line conditioning, series compensation, phase shifting, voltage balancing, fuel cell and photovoltaic utility systems interfacing, etc. The new M-level inverter consists of (M-1)/2 single phase full bridges in which each bridge has its own separate DC source. This inverter can generate almost sinusoidal waveform voltage with only one time switching per cycle as the number of levels increases. It can solve the problems of conventional transformer-based multi pulse inverters and the problems of the multilevel diode-clamped inverter and the multilevel living capacitor inverter. To demonstrate the superiority of the new inverter, a SVG system using the new inverter topology is discussed through analysis, simulation and experiment [11-15]. The D-STATCOMs are normally placed in parallel with the distributed generation systems as well as the power systems to operate as a source or sink of reactive power to increase the power quality issues of the power lines. Using regular STATCOMs for small-to-medium size single-phase wind applications does not make economic sense and increase the cost of the system significantly. This is where the idea of using smarter WEIs with FACTS capabilities shows itself as a new idea to meet the targets of being cost- effective as well as compatible with IEEE standards. The proposed inverter in this paper is equipped with a D-STATCOM option to regulate the reactive power of the local distribution lines and can be placed between the wind turbine and the grid, same as a regular WEI without any additional cost. The function of the proposed inverter is not only to convert dc power coming from dc link to a suitable ac power for the main grid, but also to fix the PF of the local grid at a target PF by injecting enough reactive power to the grid [16]. In the proposed control strategy, the concepts of the inverter and the D-STATCOM have been combined to make a new inverter, which possesses FACTS capability with no additional cost
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design guidelines for development near high voltage overhead lines

design guidelines for development near high voltage overhead lines

Recent Government policy statements on creating well designed environments and an emphasis on the quality of the public realm, together with the broader professional and public debate about urban design and regeneration issues, all help to create a clear context for these guidelines. Design is seen as central to achieving the objectives of sustainable development. Design can not only raise the visual quality of the urban environment, but can assist in stimulating varied communities that offer greater choices to residents and workers and also rely much less on private car use. Achieving the objectives of sustainable development implies a more compact urban form, to which fresh design ideas can add value and bring high levels of amenity and quality.
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