Application Analysis and Prospect Forecast of HVDC Control System: A Survey
In this paper, the development and actuality of high voltage direct current (HVDC) transmission technology in China are presented firstly. Then, taking the HVDC control system for a survey objective, the comparison and analysis of two different HVDC control systems produced by ABB and Siemens respectively are carried out. Besides, aiming at practical HVDC projects, the existing problems and defects of their control systems are summarized, and accordingly some possible solutions are suggested. At the end, the application trends of the HVDC control system are forecasted. Introduction High voltage direct current (HVDC) technology has been considered as a viable alternative to AC for long distance power transmission and interconnection of power systems. According to China’s energy distribution and load demand, HVDC technology may play an important role in promoting power grid construction and optimizing energy configuration [1, 2]. In addition, it is predicted that the total installed capacity will exceed 1.2 billion kilowatts by the end of 2020, and in consideration of transmitting the new added power securely and reliably, the application and development of HVDC power transmission system will be indispensable. Based on the power network planning established by State Grid Corporation of China (SGCC), by the end of the 11th Five-Year Plan (from 2006 to 2010), SGCC has 17 HVDC projects whose transmission power can reach 40 million kilowatts. In the “twelfth Five-Year" period, seven ±800kV Ultra HVDC projects and a ±660kV HVDC project will be completed, and their total transmission power can be up to 80 million kilowatts. Furthermore, in the Five-Year Plan from 2016 to 2020, SGCC will have 39 HVDC projects, and their transmission power can rise to 187 million kilowatts [3]. Since the successful construction and reliable operation of Xiangjiaba-Shanghai project fully proved the performance of ±800kV UHVDC technology, considering the huge power export of Sinkiang and Tibet area, SGCC has started the R&D of a UHVDC technology with higher voltage level, and its selected rated voltage is ±1100kV. In 2012, the ±1100kV converter transformer prototype passed type test, and it could well meet the capability demands of national standard. In addition, the ±1100kV/5000A UHVDC thyristor valve has been developed by China XD Group [4]. The effective design of the above-mentioned main components can lay a good foundation for future UHVDC project. As a matter of fact, whether for classic HVDC transmission project or for UHVDC transmission project, its control system, which can directly adjust the amplitude and direction of HVDC transmission power to meet the operating requirements, is certainly the project’s heart. In other words, the performance of each HVDC project will dramatically depend on the correct and credible operation of its control system. But the existing HVDC control system still has some problems and defects, and along with the interconnection of national power grids and the introduction of smart grid step-by-step, many new requirements are put forward for the HVDC control system.