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Series Hybrid Converter (SHC)

HVDC System

Adlan B Pradana

2010EEP3791

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SCC (Self Commutated Converter vs. LCC

(Line Commutated Converter)

SCC

Immune to the strength ofnetwork (+)

Controllable power factor (+)

Can be used in a voltagesupport role (+)

Permit the elimination oflower order harmonic filters

(+) Excessive cost (-)

Smaller ratings compare toLCC (-)

LCC

Extensively used (+)

Require reactive power

source (-)

Difficult to operate in weak

system (-)

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SCC + LCC = Hybrid HVDC System

There are 2 arrangements :

Back 2 back (B2B)

Series Hybrid Converter (SHC)

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Back to Back (B2B)

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Series Hybrid Converter (SHC)

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B2B vs. SHC

Hybrid HVDC

SCC only in one side, so its

advantages also only in one

side (inverter/rectifier)

Only for a new built system

SHC

SCC can be installed on both

side, so its advantages also

for both side (inverter &rectifier)

Can be used both for a new

built system or add on

(upgrade)

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SHC

Combination of LCC and VSC in one bus

LCC provides part of the required real power, VSCadd the remainder

VSC controls reactive power necessary for theLCC

2 types :

VSC as add on of existing LCC HVD VSC + LCC for a new system

SVSC = [PVSC2+QVSC

2] 1/2

= [(Pnom PLCC )2 + (0.6 *PLCC Qfilt )

2] 1/2

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Control

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Control (LCC)

Current order is generated using external PIpower regulator

Angle orders is based on :

Terminal power mismatch Current in HVDC circuit

Measured extinction angle at rectifier and

inverter

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Control (SCC)

VSC Control block P & Q orders are derived from external regulators for

dc & ac side voltages respectively

Magnitude and angle driving signals are issued based

on : Capacitor voltage (Vdc) mismatch generates P

Terminal voltage (Et) mismatch generates Q

Terminals d & q axis components of voltage (Et,Eq)

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Start Up Comparison

LCC Only SHC

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Step Response Comparison

LCC Only SHC

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Conclusion

SHC system combining advantages of LCC andVSC

SHC can be applied both as add on or as a new

system Response of SHC is better than LCC alone :

Excellent start up

Terminal voltage support

Superior step response Acceptable fault recoveries

The disadvantages is more complexity in control

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References

B. Qahraman (IEEE student member), A. Gole (IEEEmember), A VSC Based Series Hybrid Converter forHVDC Transmission, Canadian Conference Electricaland Computer Engineering on 1-4 May 2005

Li Guangkai, Li Gengyin (Member IEEE), Liang Haifeng,Zhao Chengyong, Yin Ming Research on HybridHVDC, Power System Technology - POWERCON 2004

Y Iwata, S Tanaka, K Sakamoto H Konishi, H Kawazoe,Simulation Study of a Hybrid HVDC System Composedof a Self-commutated Converter and a Line-commutated Converter

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Thank You