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Netra Gyawali, PhD (Associate Professor) IOE, Pulchowk Campus, TU. HVDC Network as Infrastructure for Smart SAARC Power Grid . Contents. Background Key Attributes of High Voltage Direct Current (HVDC) Transmission HVDC Transmission: Configuration and Modalities
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Netra Gyawali, PhD (Associate Professor) IOE, Pulchowk Campus, TU HVDC Network as Infrastructure for Smart SAARC Power Grid
Contents Background Key Attributes of High Voltage Direct Current (HVDC) Transmission HVDC Transmission: Configuration and Modalities HVDC Transmission: World Picture HVDC Transmission: SAARC Context HVDC Network in SAARC: Possibilities Conclusions
Background Requirement of Modern Transmission GRID • Effective ( Functions as desired) • Speed and accuracy • Efficient (Low Loss) • Asset Management (Optimum use the asset) • Resilience • Interoperability • Accommodate Large Scale Renewable Power
Key HVDC Attributes • No reactive losses • Provision for high cable length • Lower electrical losses • Accommodate Renewable Power • BTB connection • Better Voltage Ride through Capability • The Power Flow on an HVDC link is Fully Controllable (Fast and Accurate) • The operator or automatic controller determines how much power flows via the link and in which direction Irrespective of the interconnected AC system conditions
Key HVDC Attributes • An HVDC Link is asynchronous • The ac voltage and frequency in the two ac networks can be controlled independently of each other • No need for common frequency control • The HVDC link can be used to improve the dynamic conditions in both of the interconnected ac networks (power system damping) • Can be controlled independently of AC system variations • HVDC links do not increase the Short Circuit Level of the connected systems • Faults and oscillations don’t transfer across HVDC interconnected systems • Firewall against cascading outages
Key HVDC Attributes • HVDC can transport energy economically and efficiently over longer distances than ac lines or cables • Increased Transmission Capacity in a fixed corridor Up to 3 times more power per tower, therefore narrower rights of way
Key HVDC Attributes Source: IEEE Magazine 2008
HVDC Transmission: Concept Source: IEEE Magazine 2008
HVDC Transmission: Concept Natural Commutation Based HVDC • Thyristor or mercury-arc valves • Reactive power source needed • Large harmonic filters needed
HVDC Transmission: Concept VSC Based HVDC • Natural Commutation Based HVDC • IGBT valves • P and Q (or U) control • Can feed in passive networks • Smaller footprint • Less filters needed
HVDC Transmission: Configuration Source: IEEE Magazine 2008
NORMAL POWER DIRECTION Source: VG Rao 2005
HVDC Transmission: Some Examples Norway Netherland Line
HVDC Transmission: Some Examples The first HVDC Light transmission
HVDC Transmission: Some Examples VSC HVDC example: troll (north sea) • Commissioning year: 2005 • Power rating: 2 x 42 MW AC Voltage:132 kV at Kollsnes, 56 kV at Troll • DC Voltage: +/- 60 kV • DC Current: 350 A • Length of DC cable:4 x 70 km
HVDC Network in SAARC (BTB Link) NR ER ER SR SR Source power grid India
HVDC IN INDIA Bipolar Source power grid India
SAARC HVDC Link: Possibilities • India-Pakistan • Nepal-India • Srilanka-India • Bangladesh-India • Bhutan-India • Afghan-Pakistan
Conclusions • HVDC transmission has number of benefits for bulk power transmission; namely efficiency, resilience, interoperability etc. • In short distance, BTB HVDC provides smart link for frequency conversion and renewable power integration. • In SAARC Country, the development of HVDC is only limited to India. For cross-border transmission link, HVDC is a good candidate. • Combining with FACTS technology, HVDC provides a infrastructure of the future Smart Transmission Grid for SAARC.
References • Understanding Facts: Concepts and Technology of Flexible AC Transmission Systems, Narain G. Hingorani, Laszlo Gyugyi • Flexible AC transmission systems, Song & Johns • Thyristor-based FACTS controllers for electrical transmission systems, MathurVama