HVDC INTERCONNECTION SYSTEM
Thailand and Malaysia have long enjoyed close cooperation,particularly in the energy sector,which has significantly contributed to the enjoy security and development of both nations.Among those cooporative efforts is the interconnection of transmission networks.The 300 MW Thailand – Malaysia High Voltage Direct Current (HVDC) Interconnection System is the second stage of the grid interconnection between EGAT of Thailand and TNB of Malaysia.The new interconnection,which represents of the first cross-border DC link in the ASEAN region.is an important stepping – stone to the realization of the ASEAN Power Grid which will significant enhance the greater energy security and economic integration of the region.
300 MW Thailand – Malaysia HVDC interconnection system consits of Khlong Ngae converter station on the Thai border and
Gurun converter station on the Malaysia border.Both stations are linked by a
300 KV DC overhead transmission line of 110 km. EGAT’s Khlong Ngae converter station is situated at Sadao district in
Southern Songkhla province ,about
24 km.from Thai-Malaysia border. TNB’s Gurun converter station is located in Kedah,about 86 km. from
Power Supply System of
Demand in southern province has previously been met by generation from the above mentioned power sources,the power transfer via the 115 kv and 230 kv central – southern tie lines,and the power exchange with Malaysia.In 2002 ,maximum power demand of Thailand’southern system amounted to 1,356.20 MW.According to the recent load forecast, the demand is projected to increase to 3,547 MW by the year 2016,or an average annual growth of 7% over the next 15 year period.Although EGAT plans to upgrade to central-southern tie line with the addition of 500 kv system,no power generating facilities will be put into the system after the oil-fired Krabi power plant.Thus the new HVDC interconnection system will help improve reliability of the power system of Southern Thailand.
Historical Background of EGAT – TNB Interconnection
A concept of interconnection the electric power networks of Thailand and Malaysia was first the conceived in the early 1970s with the prime objective of emergency assistance and economic power exchange due to the time difference in peak demand of the two systems.The first alternating current (AC) interconnection between EGAT’s Sadao substation and TNB’s Bukit Keteri(Chuping) substation became operation since February 1981,allowing a power of up to 80 MW via a 115/132 kv transmission line of 24.5 km length.
However ,the existing interconnection was too small to tie the two system for synchronous operation.As a result ,during the power exchange , the power system had to be operated in such a way that EGAT’s southern system or TNB’s northern system had to be isolated from their own main grid in order to be connected to the network of the other system. Due to the capacity and stability restriction of the existing AC interconnection, in 1988 EGAT and TNB explored the feasibility of upgrading the interconnection to future expand the power transfer capability. Following the studies, and HVDC interconnection was adopted by the two utilities as the HVDC system could provide solutions to the synchronization problem. It also allows full bi-directional control of power interchange and improves reliability and dynamic performance of both AC transmission systems.
Sophisticated Transmission Technology for the 21st Century
The Thailand – Malaysia HVDC interconnection project establishes a new efficient interconnection between Khlong Ngae converter station in southern Thailand and Gurun converter station in northern Malaysia.Both converter stations are linked by a 300 kv DC overhead line of 110 km (approximately 24 km on the Thai border and 86 km on the Malaysian border). Initially,the converter station is configured as a monopolar converter with the power transfer capacity of 300 MW.Provision has also been made for adding a second 300 MW pole in the future to extend the system into a bipolar configuration with a total transfer capability 600 MW.
Project implementation started in August 1997.A joint implementation
Committee was set up by EGAT and
TNB to oversee and ensure the
consistent project implementation by
both utilities. Each of the utilities is responsible for the HVDC station and
the DC transmission line in the
The new DC transmission system includes the contruction of a new Khlong Ngae converter station and a 300 kv bipolar DC line of 24 km linking Khlong Ngae station with the HVDC system on the Malaysian border.The converter station features major components including smoothing reactor.converter transformers,thyrister valves.DC hybrid filters, AC filter banks, DC measuring device as well as state -of - the art decentralized control and protection system.
The reinforcement of EGAT’s existing AC transmission system involves the construction of the following transmission facilities :
· A 230 kv AC substation at the side of Khlong Ngae station
· A 230 kv AC double circuit line of 30 km linking Khlong Ngae station with Hat Yai 2 substation
· A 230 kv AC double circuit line of 210 km linking Khlong Ngae station with Thung Song substation
· A 230/115/33 kv AC Thung Song substation,and
· The reinforcement of the existing 230 kv AC Hat Yai 2 substation.
Construction of the 300 MW Thailand – Malaysia HVDC Interconnection on the Thai side was completed in September 2001 at a total cost 4,980 millions baht.A new HVDC system interconnection Agreement was sign between EGAT and TNB on May 14,2002.Commercial operation of the new HVDC interconnection officially started on June 3,2002.
The DC monopolar converter station is currently capable of transmitting a full rated power of 300 MW(300 kv,1,000 A) in either direction up to a maximum ambient temperature of 39° C.The DC transmission line also permits a 10-minutes – overload of 450 MW of power once per day.According to the agreement, both EGAT and TNB agreed to initially generate and deliver 30 MW power as an obligatory energy to enable the continuous operation of the HVDC interconnection .Commercial energy is the energy sold and purchased at any time request by either utility.
Enhancing Mutual Energy Security
· Economic exchange of power between two different networks
· Enhancing system reliability
· Reduction of reserve capacity of both countries’power systems by sharing spinning reserve
· Sharing of HVDC system operational and maintenance experience
A Stepping – stone to the Integrated ASEAN Power Grid
The HVDC interconnection system marks another successful cooperation effort between Thailand and Malaysia in future building up mutual energy security.The project will not only benefit the two nations,but also all ASEAN countries as a whole.As the first cross-border DC link in the region,the Thailand – Malaysia HVDC interconnection system has been included in the ASEAN Interconnection Master Plan Study as part of the ASEAN Power Grid.The success of the Thailand – Malaysia interconnection will greatly help accelerate the integration of the ASEAN power networks which will significantly enhance the region’s sustainability and security of energy supply for the benefit of the people of all countries in the region.
ASEAN POWER INTERCONNECTION PROJECTS
100 mh,single core
3 x 116 MVA, 1 phase – 3 winding
T 1501 N75T-S34
12 group valves indoor air insulation suspension type
No. of thyristor per valve : 48,
Blocking voltage : 8 kv /1550 A
DC hybrid filters
Passive part filter (12/24 harmonics)
Active part filter (6/15/21/24/27/33/36/42/48 harmonics)
DC, 110 km (24 km on
Pole conductor : 546 mm2 (ASCR Cardinal)
Neutral conductor :298 mm2 (ASCR Hen)
Siemens AG ,