First, domestic and foreign technology status and development trend

High voltage direct current (HVDC) technology, since its rise in the 1950s, has experienced more than 40 years of development, has become an increasingly mature technology. By 1995, 62 HVDC projects had been successfully put into operation in the world, and it is expected that about 20 more HVDC projects will be put into operation by 2002.

In the 1980s, with the development of thyristor technology and the world power grid technology, HVDC technology has achieved a step development. First, due to the requirements of networking, there are 14 back-to-back projects, accounting for about half of the new projects; Second, it has built the longest DC line in the world. The 1,700 km Inga-Saba project in Zaire and the 3,150MW Itap Project in Brazil, which has a high voltage rating (600KV) and a large transmission capacity (3,150MW).

In the 1990s, a complex three-end HVDC project (Quebec-New England Project) was completed and the world's longest sea cable (250km)HVDC Project (BALTIC Project from Sweden to Germany) was built.

HVDC technology is starting to take off in Asia. The Philippines, South Korea, Malaysia, Thailand, India, Japan and China have all started the construction and research of HVDC projects, and about 15 projects have been built or are planned.

With the development of power grid technology and power electronics technology, HVDC technology will continue to deepen its strong controllability characteristics, while overcoming some adverse factors (such as harmonics) brought to the power grid and the weakness of the high cost of the casting station, to strengthen its role in the development of the power grid.

Ii. Overall objectives and tasks of technological development

According to the needs of the Geshanghe Tianguang HVDC project, the Three Gorges Project, the west-east power transmission project and the national networking project, develop our HVDC technology; Develop long distance HVDC transmission and back-to-back HVDC technology, learn from domestic and foreign experience, to ensure the successful construction and operation of the Three Gorges HVDC project; Implement the HVDC master equipment localization project.

Iii. Main technology development contents and indicators

(I) Formulating HVDC technical standards and HVDC engineering design specifications in line with international standards.

(2) Engineering operation technology

1. Research on control protection strategy of DC system;

2. Research on the coordination and cooperation of DC and AC systems and equipment control protection;

3. Study on the interaction between AC and DC systems;

4. Study on AC harmonics and their filters in converter station;

5. Development and research of new converter station operator monitoring system;

6. Research on grounding.

(3) The improvement and development of HVDC technology research means

l.HVDC engineering system research, design software package perfection and specification;

2. Improvement and development of new mathematical models of HVDC primary and secondary equipment;

3. Development of HVDC grounding research software.

(4) The study of the HVDC system, including the selection of voltage levels, the selection of main equipment parameters, the study of the system and its control strategy, etc.

(5) Research on new DC transmission technologies, including the development of automatic adjustable AC filters and active DC filters, outdoor valve technology, converter technology of series capacitors (CCC), deep-buried ground pole technology, multi-terminal DC technology, etc.

(VI) Localization of HVDC master equipment.

Iv. Economic and Social benefits and market prospects

The above research and development work will directly serve the Three Gorges power transmission and transformation project and the national networking project, as well as the HVDC project already built or under construction. It will promote China's own engineering specification design and the demand for the localization of some main equipment, and improve the reliability of HVDC project operation, which will produce great social and economic benefits.