Power Electronics Technology for Smart Grid

Power electronics technology is a modern technology that uses power electronic devices to transform and control electric energy. It can save energy by 10% to 40%, reduce the size of electromechanical equipment and achieve optimal working efficiency. At present, semiconductor power components are developing towards high voltage and large capacity. The power electronics industry has seen the emergence of flexible AC transmission technology represented by SVC, new ultra-high voltage transmission technology represented by high-voltage DC transmission, electrical drive technology represented by high-voltage frequency conversion, synchronous breaking technology represented by intelligent switches, and user power technology represented by static VAR generators and dynamic voltage restorers.

Flexible AC transmission technology is one of the key technologies for large-scale access of new energy and clean energy to the power grid system. It combines power electronics technology with modern control technology and continuously adjusts and controls power system parameters to significantly reduce transmission losses, improve the transmission capacity of transmission lines and ensure the stability of the power system.

HVDC transmission technology has unique advantages for long-distance power transmission and HVDC transmission. Among them, the light DC transmission system uses GTO, IGBT and other turn-off devices to form converters, making medium-sized DC transmission projects competitive even at shorter transmission distances. In addition, converters composed of turn-off devices can also be used to supply power to isolated small systems such as offshore oil platforms and islands. In the future, they can also be used in urban power distribution systems to access distributed power sources such as fuel cells and photovoltaic power generation. Light DC transmission systems are more helpful in solving the problem of clean energy access stability.

The biggest advantage of high-voltage frequency conversion technology is that the power saving rate can generally reach about 30%, but the disadvantage is that it is costly and produces high-order harmonics that pollute the power grid. Synchronous breaking (intelligent switch) technology is to complete the circuit opening or closing at the specified phase of voltage or current. At present, most high-voltage switches are mechanical switches, which have long breaking time and large dispersion, making it difficult to achieve accurate phase-fixed breaking. The fundamental way to achieve synchronous breaking is to replace mechanical switches with electronic switches.