HVDC TRANSMISSION Under Guidance Dr. Shahnaz Ayub Er.Kamini Prajapati Submitted By Mayank Kumar

INTRODUCTION The conversion of electrical current from AC to DC (rectifier) at the transmitting end, and from DC to AC (inverter) at the receiving end.

ORIGIN In 1882, a 50-km-long 2kV DC Transmission line was built between Miesbach and Munich in Germany.

TYPES OF HVDC Back-to-Back Converters Mono polar Transmissions Bipolar Transmissions

B ACK TO BACK CONVERTORS Back-to-back converters are mainly used for power transmission between adjacent AC grids which can not be synchronized Back to Back Convertor South East Vienna

M ONOPOLAR TRANSMISSION For very long distances and in particular for very long sea cable transmissions, a return path with ground/sea electrodes is the most feasible solution. Monopole with ground return path

B IPOLAR TRANSMISSION A bipolar is a combination of two poles in such a way that a common low voltage return path, if available, will only carry a small unbalance current during normal operation. Bipolar balanced operation

A RRANGEMENT OF HVDC POWER TRANSMISSION

M AIN CONSTITUENTS Thyristor Valves Convertor Transformer Smoothing Transformer Harmonic Filter DC Transmission Cables And Insulators

T HYRISTOR VALVES Thyristors are used as switches. Valve cooling Water Oil Flame Resistance SF 6 Thyristor valve stacks used for long distance transmission of power.

C ONVERTOR T RANSFORMER The converter transformers transform the voltage of the AC bus bar to the required entry voltage of the converter converter transformer at Siemens Plant

S MOOTHING REACTOR Prevention of intermittent current Limitation of the DC fault currents Prevention of resonance in the DC circuit Reducing harmonic currents including limitation of telephone interference

H ARMONIC FILTER AC Harmonic Filter absorb harmonic currents generated by the HVDC converter and thus to reduce the impact of the harmonics on the connected AC systems, like AC voltage distortion. DC filter circuits, which are connected in parallel to the station poles to smoothen dc and reduces interference with communication lines.

D C T RANSMISSION LINES DC transmission lines are part of overall HVDC transmission contract either within a turnkey package or as separately contracted stand-alone item.

HVDC Transmission Lines are used for crossing the sea lines

INSULATORS

AC VS DC TRANSMISSION No Inductive & Capactive elements in DC TransmissionDifferent frequency AC lines cannot be connected directly For distance more than 40 km HVDC offers only Transmission option

MERITS Economic Considerations Environmental Issues

C ONCLUSION A high-voltage, direct current (HVDC) electric power transmission system uses direct current for the bulk transmission of electrical power. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. The next 25 years‘ll be dominated by "force commutated converters“. Thyristor or semiconductors with gates that are actively controlled by separate switching circuituary.

REFERENCE classic/ - United States HVDC_Transmission ExpertOpinionreport Donald G. Fink and H. Wayne Beaty. Standard Handbook for Electrical Engineers. McGraw-Hill Professional..

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