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  • MARCH 2018


    Training Calendar


    Piyush Patel (Managing Director)

    Customer’s Voice

    Swami Vivekanand was traveling in a train, in a first class compartment. There were two British officers, traveling in the same compartment. Looking at his simple saffron clothes and thinking that he is a Sanyasi and does not know English, they started commenting. "These Sanyasies are parasites on our society, they do nothing and are simply a burden on us!" Swamiji kept his cool. After some time the train stopped. The station master, another British person, came to the train and

    spotted Swamiji. They happened to know each other. "Oh, how are you Swamiji? Do you want anything?", asked the station-master looking respectfully at Swamiji. "Just a glass of water", replied Swamiji. The train started again. The two britishers were little embarrassed. "You know English", said one of them to Swamiji."Yes!" replied Swamiji . "That means you understood whatever we were saying about you. You had nothing to say?". Swamiji looked at them and said "It is not for the first time, that I met with fools!. Fools try to judge a person by his clothes and draw their own baseless conclusions!" Ashamed of themselves, the two Britishers apologized Swamiji and touched his feet.

    High oltage V DC T HVDCransmission ( )

    and armonics H

    Digital excitation and control system


    Aging Furnace Application

    STALL NO : 8 HALL NO : H8B18 -Amtech Family

    ¨ Happy Holi-Dhuleti ¨ Happy Cheti Chand ¨ Happy Ram Navmi ¨ Happy Mahavir Jayanti ¨ Happy Good Friday

    The test of a good coach is that when they leave, others

    will carry on successfully

    Shree Kumaran Alloys


  • 3



    Introduction :

    High Voltage DC Transmission involves stepping up and rectification of the voltage to be transmitted, to convert it into high voltage DC and transmit it to a long distance of the order of hundreds of miles. At the receiving end the high voltage DC is inverted and stepped down to make it suitable for power distribution at the receiving end. This type of transmission has advantages of economy and efficiency at the same time it has side effects of harmonic generation. This paper gives the details of these advantages and also gives the methods of harmonic mitigation.

    Historical back ground of HVDC transmission:

    1950 : 116 km transmission line was commissioned between Moscow to Kasira at 200 V. k

    1954 : The first commercial HVDC line was built with 98 m Submarine cable with ground return between island k

    of Gotland and Swedish Mainland.

    1972 : The Nelson River HVDC transmission line of 550 miles delivered electric power of 2500 MW, from Kettle

    generating station to Winnipeg.

    1990 : In India 1000 MW Rihand to Dadri HVDC line was commissioned.

    1997 : The first application of DC distribution system in Sweden of HVDC is known as "HVDC light".

    2000 : 600 V DC 785 transmission line in Brazil. k km

    Advantages of High Voltage DC transmission:

    1) HVDC is more efficient. This is because it is a DC transmission at high voltage which reduces the current and

    hence the I²R losses.

    2) Transmitter and receiver can operate at different frequencies this is advantageous in some countries like

    J apan where part of the country works at 50 Hz and remaining works at 60 Hz.

    3) Power flow can be in both the directions.

    4) DC interconnection does not increase the maximum fault current in either AC systems.

    5) Delivery of power is almost at unity power factor.

    6) The power flow through HVDC transmission line can be regulated against line and load regulations.

    Dis-advantages of HVDC transmission:

    1) HVDC transmission generates harmonics when at transmission end AC power is rectified. At the receiving

    the output of inverter needs to be filtered to get pure sine wave.

    Effects of Harmonics:

    1) Each transmission line has many natural resonant frequencies determined by its length, geometry and

    termination. The input impedance of the transmission line can be closed to zero and resistive during series

    resonance or infinitely large during parallel resonance at natural resonance frequencies. If a series

    resonance frequency is close to any of the dominant harmonics generated by converter at transmission end

    severe telephone interference is expected.

    2) Current harmonics injected by converter on transmission side lead to voltage distortion.

    3) Harmonics increase copper, iron and eddy current losses in transformers, motors and generators.

    4) Power factor improvement capacitors are stressed due to high frequency voltage harmonics.

    5) The fuses, switchgear and relays lead to premature failure/tripping causing shut downs of plants.

    6) Harmonics also reduce effective power factor.

    Mitigation of harmonics:

    1) 3-phase converter gives total current distortion of nearly 62%. However, 12 pulse converter gives 8% total

    harmonic distortion of current and 18 pulse converter result in further reduction in total harmonic distortion of

    current by reducing it to less than 2%.

    2) Passive harmonic filter and Active harmonic filter which are connected in shunt with the harmonics source

    can reduce the current harmonics and can bring it within limits specified by IEEE 519:1992 standard.

    Conclusion :

    , If harmonics are taken care of HVDC transmission is the ideal power transmission over long distance.


    Payback period Approximately 8-10 Months

    Industry : Steel Application : anID F Motor rating : AC Induction Motor, 3 Phase - kW : 810 olt V : 3300 RPM : 741 Hz : 50 mp A : 188 Previous system : Motor was running on DOL starter. Problem observed : 1) High maintenance cost. 2) Energy losses due to flow control by damper. Present system : 870 kW Axpert-Hivert Series Medium Voltage Drive used. kW (Consumption) Damper Position Previous system (Without drive) : 589 kW 80 % Open Present system (With drive ) : 341 kW 100 % Open System block diagram :

    Merits of new system : 1. Easy & Smooth Operation. 2. Energy Saving due to flow control by VFD. Economical analysis :

    8Energy consumption without VFD - P1 = 589 kW 8Energy consumption with VFD - P2 = 341 kW 8Energy saving per day ((P1-P2) 24) = 5952 Units. x 8Saving per day @ Rs. 3/- Unit = Rs 17856/- . 8Saving per year (Approx. 300 Days) = Rs 53,56,800/- .



    3300 V,


    870 kW ID FAN



    Title: Digital excitation and control system DECS-150

    Additional Features and Functions:

    Ÿ Automatic voltage matching to the bus voltage when being paralleled

    Ÿ Bumpless transfer between active and inactive modes of operation

    Ÿ Integrated Power System Stabilizer (optional) • Allow for up to three (3) preposition settings

    Limiter functions:

    • Over excitation Limiting • Under excitation Limiting• Stator Current Limiting • Under frequency.

    Protection :

    • Loss of sensing • Generator over voltage • Generator under voltage • Generator over frequency

    • Generator under frequency • Exciter eld over voltage • Exciter diode open detection • Exciter diode short detection • User

    programmable protection • Syn-check Protection • Generator frequency Less than 10 Hertz • Congurable Protection

    PC software:

    Set up via PC using BESTCOM Plus Software and integrated PLC for Customizable logic

    Password protection


    USB type B port (front or rear panel optional) Ethernet: RJ45 jack (rear panel) 10BASE- T/100BASE-TX (copper)

    Diagnostics and event recording

    Ÿ R • Oscillograph • Sequence of events record up to 1000 time.eal time monitoring

    Physical requirements

    • HMI Eleven (11) LED indicators will be located on the front of the unit and will indicate the following conditions :

    • Manual Mode Active • Var/PF Active • Loss of Generator Sensing • OEL Active • UEL Active • Generator Over voltage • Over

    excitation Shutdown • Under frequency Active • Exciter Field Current Limit • PSS Active* • Customer Alarm



    A microprocessor based, high performance, digital excitation system ( ) will be DECS-150 supplied to provide the required excitation to the exciter eld of a synchronous generator. The digital excitation system will provide controls, limiters, and protection for the generator as outlined below. The will use BESTCOM Plus® PC software to DECS-150 monitor, control, and program the controlled parameters of the excitation system.

    Inputs and Outputs:

    Ÿ 63 V DC and 125 V DC @10 A DC pulse width modu