Application of Power Electronics


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Application of Power Electronics

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Application of Power Electronics

  1. 1. APPLICATION OF POWER ELECTRONICS IN TRANSMISSION OF ELECTRICAL ENERGY GUNJAN GUPTA 10BEC112 Dept. of Electronics and Communication Institute of Technology, Nirma UniversityINTRODUCTION during the next 5 to 10 years, viz. the line Application of Power Electronics in commutated thyristor, the gate turn-offthe field of power distribution and thyristor, and the insulated gate bipolartransmission systems is attracting wide transistor.attention because of its anticipated large scaleapplication in future. Traditional industry Line Commutated Thyristors: LTT and ETTstructure and operating principles have built are available. The peak blocking voltage isaround tightly and centrally controlled single expected to be limited to the 10 kV - 12 kVentity in a typical vertically integrated utility. range. With new or further improvedThe demands that are made on the power manufacturing technologies, improvement insystem because of unbundling of vertically current handling capability as well as inintegrated utilities to allow open access to conduction losses and dynamic parametersthird parties for transmission of power will appear possible (e.g. recovery charge, di/dt,force application of advanced controllers. It is dv/dt).then relevant to take a look at how and to whatextent power electronics can contribute to Gate turn-off thyristor. (GTO): The blockingeffective control of power distribution on the voltage and current handling capabilities arenetwork. In this paper, trends and future still increasing: 6kV, 6kA have beenprospects in utility applications of power announced and higher ratings are expected.electronics are presented. Idea is to highlight Progress in manufacturing technologies shouldsome practical applications particularly related result in reduced switching losses and snubberwith FACTS (Flexible AC Transmission requirements. However gate powerSystems) which cover a wide range of power requirements are not expected to reduce.electronics equipment in power systems. Insulated Gate Bipolar Transistor (IGBT): ItPOWER ELECTRONICS DEVICES appears reasonable to expect that for future modules, blocking voltages will increase In the past decade, there has been a above 5kV and current handling capability forremarkable progress in the high-power semi- modules to at least 2kA. To fully make use ofconductor devices such as GTO (Gate Turn- such parameters for FACTS applications, itoff) thyristors and light-triggered thyristors would be necessary that matching fast(LTT); both due to sophisticated semi- switching diodes are also available. Muchconductor technology and also owing to work seems to be necessary to substantiallydemand of higher reliability in the power reduce the high on-state Newer circuits are now evolvingwhich utilize turn-off devices to achieve self- Different Power Electronics Systems andcommutated configurations. In all utility Applications are:applications the semiconductor devices whichare used as switches offer a whole new 1. High Voltage DCdimension in controlling the high voltage The first application of power electronicssystems which was not feasible earlier. Not in power transmission is the technology ofonly are these switches much faster, they also HVDC which started by using mercurydo not wear out like the mechanical switches.From the many variations of power electronic ionic valves, then switched to thyristorsdevices it appears that three types will be and has been instrumental in pushingdominant for FACTS and HVDC applications thyristor technology to ever increasing
  2. 2. device ratings. Adoption of LTT has made The application of a static synchronousa great contribution to the development of generator to regulate reactive power and/orcompact and reliable thyristor values. The ac voltage magnitude is calledHVDC system would control bi- STATCOM. The reactive power of adirectional flow of 2.8 GW on 50.5 KM STATCOM can be adjusted continuouslylong submarine transmission cables and 50 from 100% inductive to 100% capacitivekm long overhead transmission lines by controlling the internal voltagebetween two electric power companies in magnitude.Japan thus resulting in a higher degree ofstability in power systems. 8. Unified Power Flow Controller2. Flexible AC Transmission Systems In case of UPFC, an AC voltage vectorFACTS controllers can be used to increase generated by a thyristor based inverter isthe transmission capacity up to the thermal injected in series with the phase voltage. Thelimit of transmission lines, aid in fast driving DC voltage for the inverter isvoltage control in event of contingencies obtained by rectifying the AC to DC fromand avoid loop flows causing undesirable the same transmission line.loading of certain transmission facilities.They also enhance system stability and 9. Active Filterssecurity. Trend seems to be in favour of a combined system of active and passive filter rather3. Static VAR Compensator than passive filter alone. Such a system reduces initial costs and improves efficiency.The SVC uses the conventional thyristor toachieve fast control of shunt connectedcapacitors and reactors. The SVC provides a 10. Energy Storage Systemsrapid and fine control of voltage without Battery energy storage systems and adjustablemoving parts and is readily available in speed pumped-storage generator / motorcurrent market. systems are other applications of advances in power electronics.4. Thyristor Controlled Series CapacitorThe thyristor controlled series capacitor canvary the impedance continuously to levels LIMITATIONSbelow and up to the lines natural impedance. Although application of power electronics is gaining momentum, the total5. Phase Angle Regulator revolution in power system on this accountThe phase shift is accomplished by adding or is still far ahead. Power electronics basedsubtracting a variable voltage component technologies will not appeal to the systemthat is perpendicular to the phase voltage of planners and operators till such time theythe line. This perpendicular voltage are absolutely sure that such schemes cancomponent is obtained from a transformer perform properly and reliably and theconnected between the other two phases. matters like maintenance, training covered. It and quality management are also can be6. Static Synchronous Generator easily appreciated that dependability andThe SSG consists of a self-commutated reliability are utmost important for electricconverter connected to an AC power system power industry.through a magnetic interface. CONCLUSION Power Electronics application to7. Static Synchronous Compensator power system is steadily coming up. Over the (STATCOM) years, there has been increased understanding of Power Electronic Equipment to cope up
  3. 3. with versatile applications. Devices have been TRANSMISSION OF ELECTRICALimproved to suit the applications expected of ENERGY T Adhikari Transmissionthem. Further, the unbundling of vertically Projects Division BHEL, New Delhiintegrated utilities is also forcing power 2. Semiconductor Power Devices for use in HVDC and FACTS controllers. Preparedsystem planners to adopt these applications by CIGRE working group 14.17 onwherever viable. “Semiconductor Power Devices”. 3. FACTS Overview (Draft 2, January 1994);REFERENCES CIGRE WG 14.14 1. IEEE - APPLICATION OF POWER ELECTRONICS IN THE