Floating wind turbines are attracting more attention as more than three-quarters of the total offshore technical potential is located in deep water, leading to a growing trend in floating wind farm projects. Consequently, it becomes necessary to develop Floating Offshore Substation (FOSS) to step up voltage and efficiently transmit power to the shore with minimal losses. However, the harsh environment of the sea/ocean imposes significant challenges on the substation’s electrical equipment, which need to be addressed. This research aims to address the challenges with the primary electrical equipment and provide some recommendations and considerations within the framework of offshore wind. An in-depth literature study was conducted to describe the concepts of the floating application mechanically and electrically. The fatigue analysis theory was explained, and concrete examples were presented and evaluated. Moreover, a standard offshore substation design was presented with the primary high-voltage equipment, where the offshore considerations were highlighted based on the existing standards. Ultimately, a communication channel between the windfarm developer Vattenfall AB and the manufacturer Siemens Energy was established to enable cooperation between industries to discuss the topic, and obtain results from experts’ opinions and experiences. The literature study found that the semi-submersible platform structure performs better than other concepts in different water depths and environmental conditions. The electrical equipment onboard experiences similar equivalent damage regardless of the weight. Furthermore, some specific technical challenges and recommendations on the high-voltage equipment were identified through the mentioned cooperation. For instance, oil-immersed transformers and shunt reactors have better potential than dry-type or gas-insulated types, despite decaying the oil dielectric property due to the vibrations. High-voltage Gas Insulated Switchgear (GIS) is a preferable choice to the air-insulated types. Lastly, there is a lack of standards regarding equipment testing for floating application. Identifying a valid methodology to determine the equipment’s fatigue load capability, and alternatives to the shake table test is a necessity to make this substation happen. / Flytande vindkraftverk lockar alltmer uppmärksamhet då över tre fjärdedelar av det totala tekniska potentialen för havsbaserad vindkraft finns i djupt vatten, vilket leder till en växande trend av projekt med flytande vindparker. Följaktligen blir det nödvändigt att utveckla FOSS för att höja spänningen och effektivt överföra energi till land med minimala förluster. Dock medför den hårda havsmiljön betydande utmaningar för den elektriska utrustningen på stationen, vilka behöver hanteras. Denna forskning syftar till att identifiera utmaningarna med den primära elektriska utrustningen och ge rekommendationer och överväganden inom ramen för havsbaserad vindkraft. En grundlig litteraturstudie genomfördes för att beskriva koncepten för flytande tillämpningar både mekaniskt och elektriskt. Utmattningsanalysteorin förklarades och konkreta exempel presenterades och utvärderades. Dessutom presenterades en standarddesign för havsbaserad station med den primära högspänningsutrustningen, där havsrelaterade överväganden betonades baserat på befintliga standarder. Slutligen etablerades en kommunikationskanal mellan utvecklaren Vattenfall AB och tillverkaren Siemens Energy för att möjliggöra samarbete mellan industrierna för att diskutera ämnet och få resultat från experternas åsikter och erfarenheter. Litteraturstudien visade att den halvsumpade designen presterar bättre än andra koncept i olika vattendjup och miljöförhållanden. Den elektriska utrustningen ombord upplever liknande ekvivalenta krafter oavsett vikten. Vidare identifierades vissa specifika tekniska utmaningar och rekommendationer för högspänningsutrustningen genom det nämnda samarbetet. Till exempel har oljeisolerade transformatorer och strömspolar bättre potential än torr- eller gasisolerade typer, trots att oljans dielektriska egenskaper försämras på grund av vibrationer. Högspännings-GIS är ett föredraget val jämfört med luftisolerade typer. Slutligen finns det brist på standarder för utrustningstestning för flytande tillämpningar. Att identifiera en giltig metodik för att bestämma utrustningens förmåga att hantera belastning vid utmattning, samt alternativ till shake table-test, är nödvändigt för att genomföra denna flytande havbaserad station.

Transformers emit a characteristic humming noise due to magnetostriction which is the continuous change in dimensions during magnetization. The noise is amplified if the induced frequencies match the core’s natural frequencies, consequently avoiding geometries that create resonance is critical in order to fulfill customer sound level requirements. In this thesis, a high voltage direct current transformer core with two main limbs and two return limbs is studied. Using finite element analysis (FEA), the core can be modeled and analyzed in a computer environment. The main contributors of noise are the first bending and longitudinal resonance modes. Data for how these modes change with geometric alterations is collected and stored through parametric studies. An analytical expression is then constructed through Rayleigh’s energy method with added coefficients that can be correlated to FEA datasets achieving a verified model via data-fitting. A satisfactory model is created for both resonance modes. / Transformatorer avger ett karaktäristiskt surrande ljud. Ljudet uppkommer på grund av magnetostriktion vilket är förändringar i geometri som uppkommer då kärnan kontinuerligt magnetiseras. Ljudet förstärks om induktionsfrekvenserna matchar kärnans naturliga frekvenser, så att undvika kärngeometrier som skapar resonans är viktigt för att klara ljudnivåkrav som kunden har. I denna studie betraktas resonansfenomenet i en högspänningstransformator för likström (HVDC) med två lindade ben och två sidoben. Med avstamp i en finita elementanalys (FEA) kan kärnan modelleras och analyseras i en datormiljö. Data för hur resonansmoderna som bidrar mest till ljud förändras med förändringar av geometriska parametrar samlas genom parametriska studier. I detta fall analyseras de första böj- och longitudinella resonansmoderna. Ett analytiskt uttryck skapas sedan med hjälp av Rayleigh’s energimetod där coefficienter anpassas efter FEA-datan. Detta leder slutligen till en verifierad modell som fungerar väl för uppskattning av de båda relevanta resonansmoderna.

<p>A short, 30cm, test section was used to study the effect of electrohydrodynamic (EHD) forces on flow redistribution in a horizontal, shell and tube heat exchanger subject to both boiling and condensation. The use of a short test section allows for a consistent flow pattern across the test section length which provides further insight into the true effect of EHD.</p> <p>It was found that the voltage polarity of the applied voltages influences the flow distribution. For the current geometry studied, it was found that positive polarity voltages tend to pull liquid away from heat transfer surface and that negative voltages tended to repel more liquid toward the heat transfer surface. Using this knowledge we were able to show that positive voltages were more effective for convective condensation heat transfer enhancement, whereas negative voltages were more effective for convective boiling heat transfer enhancement. A twofold enhancement of convective boiling heat transfer was achieved for positive voltages and a 4fold enhancement was achieved for negative voltages. Similar pressure drop penalties were seen for both cases, approximately twice that of the no EHD case.</p> <p>Furthermore, the effect of DC level, peak to peak voltage, frequency and duty cycle waveform parameters on convective boiling enhancement were studied to explore the range of controllability for the current set of flow parameters. It was found that these various waveform parameters can induce different flow patterns and consequently different heat transfer and pressure drop configurations. In general the heat transfer is enhanced by EHD, but different pressure drop penalties can be achieved for a given enhancement ratio using different waveforms. High heat transfer for relatively low pressure drop was achieved using either negative DC signals or 50%duty cycle pulse waveforms. In some cases the enhancement is quite little compared to the pressure drop, for example the zero DC level, varying peak to peak voltage data. It is suggested that in a system where the heat exchanger pressure drop due to EHD is more dominant than the system pressure drop, it may be possible to use EHD as a method of retarding the system rather than enhancing it thereby broadening the scope of controllability.</p> <p>Finally we showed the proof of concept of using DC EHD as a rapid control mechanism for the load conditions. Using -8kVDC the water side heat flux could be varied by approximately ±3.2 kW/m² within 5 seconds. As a comparison, the same experiment was repeated using the refrigerant flow rate to control the load. Response times were similar for both experiments and although the power required for the flow rate control was less, the minimal variability in flow parameters for the EHD control make it a more attractive method of load control.</p> / Master of Applied Science (MASc)

No description available.

One of the requirements for the next generation of power supplies for distributed power systems (DPSs) is to achieve high power density with high efficiency. In the traditional front-end converter based on the two-stage approach for high-power three-phase DPSs, the DC-link voltage coming from the power factor correction (PFC) stage penalizes the second-stage DC/DC converter. This DC/DC converter not only has to meet the characteristics demanded by the load, but also must process energy with high efficiency, high reliability, high power density and low cost. To meet these requirements, approaches such as the series connection of converters and converters that reduce the voltage stress across the main devices have been proposed. In order to improve the characteristics of these solutions, this dissertation proposes high-efficiency, high-density DC/DC converters for high-power high-voltage applications. In the first part of the dissertation, a DC/DC converter based on a three-level structure and operated with pulse width modulation (PWM) phase-shift control is proposed. This new way to operate the three-level DC/DC converter allows soft-switching operation for the main devices. Zero-voltage switching (ZVS) and zero-voltage and zero-current switching (ZVZCS) soft-switching techniques are studied, analyzed and compared in order to improve the characteristics of the proposed converter. This results in a series of ZVS and ZVZCS three-level DC/DC converters for high-power high-voltage applications. In all cases, results from 6kW prototypes operating at 100 kHz are presented. In addition, with the ultimate goal of improving the power density of the DC/DC converter, a study of several resonant DC/DC converters that can operate at higher switching frequencies is presented. From this study, a three-element ZVS three-level resonant converter for applications with wide input voltage and load variations is proposed. Experimental results at 745 kHz obtained without penalizing the efficiency of the PWM approaches are presented. The second part of the dissertation proposes a quasi-integrated AC/DC three-phase converter that aims to reduce the complexity and cost of the traditional two-stage front-end converter. This converter improves the complexity/low-efficiency tradeoff characteristics evident in the two-stage approach and previous integrated converters. The principle of operation for the converter is analyzed and verified on a 3kW experimental prototype. / Ph. D.

The advent of wide band-gap semiconductors in power electronics has led to the scope of efficient power conversion being pushed further than ever before. This development has allowed for systems to operate at higher and higher voltages than previously achieved. One area of consideration during this high voltage transition is the synchronous rectifier, which is traditionally designed as an afterthought. Prior research in synchronous rectifiers have been limited to low voltage, high current converters. There is practically no research in high voltage synchronous rectification. Therefore, this dissertation focuses on discovering the unknown nuances behind high voltage synchronous rectifier design, and ultimately developing a practical, scalable solution. There are three main issues that must be addressed when designing a high voltage synchronous rectifier: (1) high voltage sensing; (2) light load effects; (3) accuracy. The first hurdle to designing a high voltage SR system is the high voltage itself. Traditional methods of synchronous rectification (SR) attempt to directly sense voltage or current, which is not possible with high voltage. Therefore, a solution must be designed to limit the voltage seen by the sensing mechanism without sacrificing accuracy. In this dissertation, a novel blocking solution is proposed, analyzed, and tested to over 1-kV. The solution is practical enough to be implemented on practically any commercial drain-source SR controller. The second hurdle is the light load effect of the SR system on the converter. A large amount of high voltage systems utilize a LLC-based DC transformers (DCX) to provide an efficient means of energy conversion. The LLC-DCX's attractive attributes of soft-switching and high efficiency allure many architects to combine it with an SR system. However, direct implementation of SR on a LLC-DCX will result in a variety of light load oscillation issues, since the rectifier circuitry can excite the resonant tank through a false load transient phenomena. A universal limiting solution is proposed and analyzed, and is validated with a commercial SR controller. The final hurdle is in optimizing the SR system itself. There is an inherent flaw with drain-source sensing, namely parasitic inductance in the drain-source sense loop. This parasitic inductance causes an error in the sensed voltage, resulting in early SR turn-off and increased losses through the parallel diode. The parasitic will always be present in the circuit, and current solutions are too complex to be implemented. Two solutions are proposed depending on the rectifier architecture: (1) multilevel gate driving for single switch rectifiers; (2) sequential parallel switching for parallel switch rectifiers. In summary, this dissertation focuses on developing a practical and reliable high voltage SR solution for LLC-DCX converters. Three main issues are addressed: (1) high voltage sensing; (2) light load effects; (3) accuracy. Novel solutions are proposed for all three issues, and validated with commercial controllers. / Doctor of Philosophy / High voltage power electronics are becoming increasing popular in the electronics industry with the help of wide band-gap semiconductors. While high voltage power electronics research is prevalent, a key component of high voltage power converters, the synchronous rectifier, remains unexplored. Conventional synchronous rectifiers are implemented on high current circuits where diode losses are high. However, high voltage power electronics operate at much lower current levels, necessitating changes in current synchronous rectifier methods. This research aims to identify and tackle issues that will be faced by both systems and IC designers when attempting to implement high voltage synchronous rectifiers on LLC-DCXs. While development takes planes on a LLC-DCX, the research is applicable to most resonant converters and applications utilizing drain-source synchronous rectifier technology. This dissertation focuses primarily on three areas of synchronous rectifier developments: (1) high voltage compatibility; (2) light load effects; (3) accuracy. The first issue opens the gate to high voltage synchronous rectifier research, by allowing high voltage sensing. The second issue explores issues that high voltage synchronous rectifiers can inadvertently influence on the LLC-DCX itself - a light load oscillation issue. The third issue explores novel methods of improving the sensing accuracy to further reduce losses for a single and parallel switch rectifier. In each of these areas, the underlying problem is root-caused, analyzed, and a solution proposed. The overarching goal of this dissertation is to develop a practical, low-cost, universal synchronous rectifier system that can be scaled for commercial use.

The trend towards more and all-electric apparatuses and more electrification will lead to higher electrical demand. Increases in electrical power demand can be provided by either higher currents or higher voltages. Due to "weight" and "voltage" drop, a raise in the current is not preferred; so, "higher voltages" are being considered. Another trend is to reduce the size and weight of apparatuses. Combined, these two trends result in the high voltage, high power density concept. It is expected that by 2030, 80% of all electric power will flow through "power electronics systems". In regards to the high voltage, high power density concept described above, "wide bandgap (WBG) power modules" made from materials such as "SiC and GaN (and, soon, Ga2O3 and diamond)", which can endure "higher voltages" and "currents" rather than "Si-based modules", are considered to be the most promising solution to reducing the size and weight of "power conversion systems". In addition to the trend towards higher "blocking voltage", volume reduction has been targeted for WBG devices. The blocking voltage is the breakdown voltage capability of the device, and volume reduction translates into power density increase. This leads to extremely high electric field stress, E, of extremely nonuniform type within the module, leading to a higher possibility of "partial discharge (PD)" and, in turn, insulation degradation and, eventually, breakdown of the module. Unless the discussed high E issue is satisfactorily addressed and solved, realizing next-generation high power density WBG power modules that can properly operate will not be possible. Contributions and innovations of this Ph.D. work are as follows. i) Novel electric field grading techniques including (a) various geometrical techniques, (b) applying "nonlinear field-dependent conductivity (FDC) materials" to high E regions, and (c) combination of (a) and (b), are developed; ii) A criterion for the electric stress intensity based upon accurate dimensions of a power device package and its "PD measurement" is presented; iii) Guidelines for the electrical insulation design of next-generation high voltage (up to 30 kV), high power density "WBG power modules" as both the "one-minute insulation" and PD tests according to the standard IEC 61287-1 are introduced; iv) Influence of temperature up to 250°C and frequency up to 1 MHz on E distribution and electric field grading methods mentioned in i) is studied; and v) A coupled thermal and electrical (electrothermal) model is developed to obtain thermal distribution within the module precisely. All models and simulations are developed and carried out in COMSOL Multiphysics. / Doctor of Philosophy / In power engineering, power conversion term means converting electric energy from one form to another such as converting between AC and DC, changing the magnitude or frequency of AC or DC voltage or current, or some combination of these. The main components of a power electronic conversion system are power semiconductor devices acted as switches. A power module provides the physical containment and package for several power semiconductor devices. There is a trend towards the manufacturing of electrification apparatuses with higher power density, which means handling higher power per unit volume, leading to less weight and size of apparatuses for a given power. This is the case for power modules as well. Conventional "silicon (Si)-based semiconductor technology" cannot handle the power levels and switching frequencies required by "next-generation" utility applications. In this regard, "wide bandgap (WBG) semiconductor materials", such as "silicon carbide (SiC)"," gallium nitride (GaN)", and, soon, "gallium oxide" and "diamond" are capable of higher switching frequencies and higher voltages, while providing for lower switching losses, better thermal conductivities, and the ability to withstand higher operating temperatures. Regarding the high power density concept mentioned above, the challenge here, now and in the future, is to design compact WBG-based modules. To this end, the extremely nonuniform high electric field stress within the power module caused by the aforementioned trend and emerging WBG semiconductor switches should be graded and mitigated to prevent partial discharges that can eventually lead to breakdown of the module. In this Ph.D. work, new electric field grading methods including various geometrical techniques combined with applying nonlinear field-dependent conductivity (FDC) materials to high field regions are introduced and developed through simulation results obtained from the models developed in this thesis.

In this dissertation, a design approach for medium voltage (MV) PCB-based components, such as the dc bus, is detailed. Key considerations, including electric field (E-field) grading near power terminals and PCB edges, cable feedthroughs, and the integration of components, are explored from the perspective of E-field management. A design example of a 3-level dc bus for a 6 kV-1 MW Power Electronics Building Block (PEBB) is presented. This PEBB was assembled using an array of low-voltage (LV) capacitors to create 3 kV PCB-based capacitor daughtercards, applying the same design principles as the dc bus. The scalability of this design approach is demonstrated with a 9-level dc bus rated for 24 kV. The insulation quality and MV performance of all PCBs have been assessed through partial discharge (PD) analysis using an Omicron MPD 600. The high-voltage (HV) design approach takes into account the mitigation of peak electric field intensity to minimize insulation degradation caused by electrical stress. In addition to electrical stress, the current carrying capacity (CCC) of these printed circuit boards (PCBs) was assessed concerning steady-state thermal performance and short-circuit (SC) robustness. Multiple configurations were examined to determine the current density, with the aim of reducing temperature. The insulation performance following repetitive fault events was monitored. Although the Partial Discharge Inception Voltage (PDIV) reduced by 50% after 140 SC faults, it remained higher than the operational voltage. This demonstrates the feasibility of utilizing HV PCBs in practical applications. Finally, the insulation performance of a complete 6 kV PEBB assembly was assessed. The PEBB was assembled component by component, with a focus on tracking the PDIV at each stage. This approach allowed for the qualification of the PEBB for use in a 24 kV PEBB-based converter with a common mode (CM) PDIV of 33.2 kV. Subsequently, multiple PEBBs underwent testing to simulate their operation within a 24 kV converter configuration, ensuring dependable performance when assembled. Custom support structures were also designed and tested to accommodate the 24 kV PCB bus and dc-link capacitors, serving as interconnections between multiple phase legs and the external voltage source. / Doctor of Philosophy / Power electronic converters are used in many applications ranging from low power to high. Some applications include cellphone chargers, electric vehicle chargers, and even power distribution systems on land and sea. The electronics devices that are at the heart of these converters are rapidly advancing. Newer devices are being fabricated using so-called wide bandgap (WBG) materials such as silicon carbide as opposed to their older silicon counterparts. These WBG devices allow power converters to shrink in size due to their enhanced performance. As these device technologies evolve, the need to completely redesign systems to fully leverage their benefit arise. In this dissertation, the work centers around computer based simulations, coupled with hardware experiments, to design custom components that will allow engineers to significantly reduce the size and weight of medium voltage (MV) power electronic converters while also increasing their power. The printed circuit board (PCB) is a standard component used in every day electronics. They are used to host electronic components while creating precise electrical connections between them. Although these are very useful in circuits operating at lower voltages, their use has not been widely explored for applications requiring higher voltage such those as where these advancing WBG devices would provide the most benefit. A design method is introduced which allows these boards to be used at relatively high voltage (HV). The robustness of these HV PCBs were evaluated to ensure the feasibility of their continued use after multiple fault events. The size of power converter can be largely affected by the cooling system. Although the WBG devices can withstand higher temperature operation, the temperature of the device can still be a limiting factor. It is preferred to extract heat from the devices, allowing them to process more power. A standard component of cooling systems using forced air is the heatsink. The standard heatsink has corners that create sharp corners which are not ideal in high voltage systems; spacing between components must be increases to mitigate the effects caused by these sharp corners. Computer simulations were used to aid in the design of a heatsink profile which eliminates these sharp corners and was shown to reduce the clearance between cooling system components by up to 50%. Each component was individually designed and tested to ensure its reliable operation. However, it's crucial to verify their performance when assembled with other components. In addition to designing components for high voltage operation, the insulation system for a complete converter assembly was evaluated. Once a full converter was successfully qualified, a similar approach was taken to evaluate multiple converters when assembled together, much like building blocks, to construct even larger converters. This rigorous testing and assembly process ensures the reliable operation of the entire system.

Satisfaire les besoins en énergie de manière responsable est possible grâce aux énergies renouvelables, notamment éoliennes et solaires. Cependant ces centres de captation d’énergie sont éloignés dans zones de consommation. Le transport de l’énergie via des réseaux HVDC (haute tension courant continu) permet un rendement et une flexibilité avantageuse face au transport HVAC (haute tension courant alternatif). Ceci est rendu possible grâce aux convertisseurs utilisant l’électronique de puissance. Les récents développements sur les semi-conducteurs à large bande interdite, plus particulièrement le carbure de silicium (SiC) offrent la possibilité de concevoir ces convertisseurs plus simples, utilisant des briques technologiques de plus fort calibre (≤ 10 kV). Cependant le packaging, essentiel à leur bon fonctionnement, ne suit pas ces évolutions. Dans cette thèse, nous explorons les technologies actuelles ainsi que les limites physique et normatives liées au packaging haute tension. Des solutions innovantes sont proposées pour concevoir un module de puissance haute tension, impactant que faiblement les paramètres connexes (résistance thermique, isolation électrique et paramètres environnementaux). Les éléments identifiés comme problématiques sont traités individuellement. La problématique des décharges partielles sur les substrats céramiques métallisés est développée et une solution se basant sur les paramètres géométriques a été testée. Le boitier standard type XHP-3 a été étudié et une solution permettant de le faire fonctionner à 10 kV à fort degré de pollution a été développée. / The supply of carbon-free energy is possible with renewable energy. However, windfarms and solar power plants are geographically away from the distribution points. Transporting the energy using the HVDC (High Voltage Direct Current) technology allow for a better yield along the distance and result in a cost effective approach compared to HVAC (High Voltage Alternative Current) lines. Thus, there is a need of high voltage power converters using power electronics. Recent development on wide bandgap semiconductors, especially silicon carbide (SiC) allow a higher blocking voltage (around 10 kV) that would simplify the design of such power electronic converters. On the other hand, the development on packaging technologies needs to follow this trend. In this thesis, an exploration of technological and normative limitation has been done for a high voltage power module design. The main hot spot are clearly identified and innovative solutions are studied to provide a proper response with a low impact on parasitic parameters. Partial Discharges (PD) on ceramic substrates is analyzed and a solution of a high Partial Discharge Inception Voltage (PDIV) is given based on geometrical parameters. The XHP-3 like power modules are studied and a solution allowing a use under 10 kV at a high pollution degree (PD3) is given.

Ever increasing demand for electricity, exploitation of large hydro and nuclear power at remote location has led to power evacuation by long EHV/UHV transmission systems. This thesis concentrates on transient analysis of EHV/UHV transmission systems for improved planning and protection. In this thesis, the uncontrolled and controlled switching methods to limit the switching surges during energization of 765kV and 1200k VUHV transmission lines are studied. The switching surge over voltages during the energization of series compensated line are compared with uncompensated line. A Generalized Electromagnetic Transients Program has been developed. The program incorporates specific models for studying the effectiveness of various means for control of switching surge over voltages during UHV transmission line energization and also simulation of various types of faults. Since power grids may adopt next higher UHV transmission level 1200kV, these studies are necessary for insulation coordination as well as transmission line protection relay settings. A new fault detection/location technique is presented for transmission line using synchronized fundamental voltage and current phasors obtained by PMUs at both ends of line. It is adaptive to fault resistance, source impedance variation, line loading and fault incidence angle. An improved Discrete Fourier Transform (DFT) algorithm to estimate and eliminate the decaying dc component in a fault current signal is proposed for computing the phasors. The settings for digital distance relays under different operating conditions are obtained. The relay should operate faster and be more sensitive to various faults under different conditions without loosing selectivity. An accurate faulted transmission line model which considers distributed shunt capacitance has been presented. The relay trip boundaries are obtained considering transmission line model under realistic fault conditions. For different loading conditions ideal relay characteristic has been developed. The obtained trip boundaries can be used for proper settings of practical relay. An adaptive relaying scheme is proposed for EHV/UHV transmission line using unsynchronized/synchronized fundamental voltage and current phasors at both ends of line. For fault location, the redundancy in equations is achieved by using two kinds of Clarke’s components which makes the calculations non-iterative and accurate. An operator for synchronization of the unsynchronized measurements is obtained by considering the distributed parameter line model. The distance to fault is calculated as per the synchronized measurements. Support Vector Machine(SVM) is used for high speed protection of UHV line. The proposed relaying scheme detects the fault and faulted phase effectively within few milli seconds. The current and voltage signals of all phases at the substation are fed to SVM directly at a sampling frequency of 1.0kHZi.e20 samples/cycle . It is possible to detect faulted phase with in 3msec, using the data window of 1/4th cycle. The performance of relaying scheme has been checked with a typical 765kV Indian transmission System which is simulated using the developed EMTP.