HVDC Light Valve Control System Research And Prototype Design

The power electronics technology is rapidly developing and the modern power systemnetwork continues to expand, so the conventional DC transmission has been unable to meetthis demand. With the innovation of new energy technologies, the expansion of the powertransmission electric field and the development of different grid electricity trading,Whichpromoted innovation in the field of direct current transmission.The HVDC flexible technology as a new generation of DC transmission technology,which greatly extends the the DC transmission range of applications. This new DCtransmission technology has more advantages in the era of large power grids and complexsystems. And, compared to the conventional DC transmission, it has excellent characteristicsin the control flexibility, environmental protection, simplifying the converter station, greeningenergy grid and improving power quality. Therefore, it has become one hot of the currentresearches in the HVDC fields. Especially, in the situation of this new DC transmissiontechnology application in China are basically blank, many applied infrastructure issues stillneed be further studied. The main features of this new DC transmission technology is theadoption by the full-controlled power electronic devices consisting of voltage sourceconverter (Voltage-Sourced Converter，VSC), to replace the conventional DC transmissionbased on a semi-controlled thyristor devices current source converter, and it highlights thethree technical characteristics of the control of power electronic devices, voltage sourceconverter and pulse-width modulation (Pulse Width Modulation，PWM). It has used theinsulated gate bipolar transistor IGBT voltage source converter, and has the strong currentcapacity, the application of pulse-width modulation technology can be more effective passiveconverter. This function of the voltage source converter has small size, and it could reduce thefiltering device in the converter station and simplify the structure of converter station, so wecalled it HVDC flexible or HVDC Light.In addition to the advantages of the conventional HVDC, HVDC Light has moretechnical preponderances in terms of grid back-to-back, high capacity power access, silossupply and construction of multi-terminal DC networks.The new DC transmission technologybased on the voltage source converter, as the development and innovation of the conventionalDC transmission technology, has important theoretical significance and value in use of thestudy in the HVDC Light valve control system.This paper describes the basic structure, working principle, technical characteristics of HVDC Light technology, and the valve control system as a core part of the entire DCtransmission networks, its focus on the research.We design a prototype of a small-capacityHVDC Light Valve System, And make detail theoretical analysis and computer simulations inthe design of valve control system, composition and function principle. Finally, we develop avalve control system control strategy.The results show that the prototype system has goodstability, excellent anti-interference performance, strong adaptability and ability toautomatically adjust, which can meet the basic requirements of engineering applications, andit has laid a good foundation for the future engineering applications.