The document discusses multi-terminal DC (MTDC) systems. MTDC systems are used when there are multiple terminals in an HVDC transmission system. There are two main types of MTDC configurations: series and parallel. Series MTDC connects terminals in series, while parallel MTDC allows terminals to adjust currents independently and keep voltages constant. Radial and mesh are examples of parallel MTDC network topologies. MTDC systems provide benefits over multiple two-terminal HVDC links such as reduced costs and losses as well as increased transmission capacity and flexibility.

1. HIGH VOLTAGE DIRECT CURRENT TRANSMISSION
“MULTI TERMINAL DC SYSTEMS”
V.KALAIRAJAN M.E;
ASSISTANT PROFESSOR,
ELECTRICALAND ELECTRONICS ENGINEERING
KONGUNADU COLLEGE OF ENGINERING AND TECHNOLOGY,TRICHY
KONGUNADU COLLEGE OF ENGINERING AND TECHNOLOGY, TRICHY MULTI TERMINAL DC SYSTEMS 1

2. “MULTI TERMINAL DC SYSTEMS”
VIEWS :
 MULTI TERMINAL DC SYSTEMS.
 APPLICATIONS OF MTDC.
 TYPES OF MTDC.
 SERIES MTDC.
 PARALLEL MTDC.
 RADIAL AND MESH.
 CONCLUSION.
 REFERENCES.
KONGUNADU COLLEGE OF ENGINERING AND TECHNOLOGY, TRICHY MULTI TERMINAL DC SYSTEMS 2

3. “MULTI TERMINAL DC SYSTEMS”
MULTI TERMINAL DC SYSTEMS:
 Hvdc systems designed as point to point with terminals.
 MTDC used when multi terminals present in the system.
 Terminals – Rec and Inv.
 Tapping –simple way to build MTDC from existing two terminal
system.
 Complexity, production and controls are increased in MTDC.
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4. “MULTI TERMINAL DC SYSTEMS”
APPLICATIONS OF MTDC:
 Tapping power.
APPLICATION 1:
 Bulk power transmission from remote gen stations to different
load centres.
 No need of AC Collectors. Gen unit directly connected to Rec
Station.
 In load side also no need of additional lines.
 Consider two converter and two inverter system by MTDC Type.
 For the same flexibility power exchange get by three two terminal
system .
 increases additional DC links to connecting the receiving systems.
 So lines, increased losses and cost compare than MTDC.
 Elimination of AC collector give good efficiency .
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5. “MULTI TERMINAL DC SYSTEMS”
APPLICATION 2:
For more than two systems,
• In Asynchronous interconnection between power systems MTDC
is best than several two terminal DC links.
APPLICATION3:
• Power inject by one line is create over load in Ac output side. So
MTDC is better to reduce the overloaded systems.
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6. “MULTI TERMINAL DC SYSTEMS”
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7. “MULTI TERMINAL DC SYSTEMS”
TYPES OF MTDC:
 Series system
 Parallel system
 Radial type
 Mesh type
SERIES MTDC:
 Natural extension of two terminal systems which is a series connected system
 Three Terminal MTDC System:
 In this series connected three terminal system act as monopolar system.
 Ground is only at one point.
 Insulation cost is high.
 Current is same all station which is set by one station.
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8. “MULTI TERMINAL DC SYSTEMS”
SERIES MTDC:
 Fault clearance, power reversal, are same as two terminal systems.
 High speed power reversal.
 Voltage rating of valves related to power.
 Cheaper (insulation cost is high).
 Line and valve losses are high.
 Insulation coordination problems.
 Permanent fault in line of one station means it affects other
stations also.
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9. “MULTI TERMINAL DC SYSTEMS”
PARALLEL MTDC:
 Current of all converter station can adjust for power requirement.
 Voltage is constant.
RADIAL AND MESH:
 Disconnection of one segment affects other stations power transfer
(Radial).
 Power reversal is not possible without mechanical switching.
 Current rating of valves related to power.
 Adding parallel converters in stations for development of power
requirement.
 Less losses.
 Just remove the faulted converter segment. So it not affect others
directly.
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10. “MULTI TERMINAL DC SYSTEMS”
RADIAL TYPE PARALLEL:
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11. “MULTI TERMINAL DC SYSTEMS”
MESH TYPE PARALLEL:
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12. “MULTI TERMINAL DC SYSTEMS”
CONCLUSION:
 In this above presentation we can learn about basic concept of
multi terminal dc systems, applications of MTDC, types of
MTDC, series MTDC, parallel MTDC, radial and mesh.
REFERENCES:
 Padiyar, K. R., “HVDC power transmission system”, New Age
International (P) Ltd., New Delhi, Second Edition, 2010.
 Edward Wilson Kimbark, “Direct Current Transmission”, Vol. I,
Wiley interscience, New York, London, Sydney, 1971.
 Kundur P., “Power System Stability and Control”, McGraw-Hill,
1993.
 Google and wikipedia.
12KONGUNADU COLLEGE OF ENGINERING AND TECHNOLOGY, TRICHY MULTI TERMINAL DC SYSTEMS