An innovative hybrid PWM technology for VSC in application of VSC-HVDC transmission system

This paper presents an innovative hybrid PWM technology, its corresponding structures and characteristics suitable for high voltage direct current transmission system based on voltage source converter (VSC-HVDC). The features of optimized PWM (OPWM) are presented and a new algorithm based on the theory of power sums for solving non-linear transcendental equations is introduced. The properties of 3^rd harmonic injection SPWM are also presented. The working mechanism and configuration of the hybrid PWM are discussed in detail. The features of mode detector (the key building block) are also presented. A two terminals VSC-HVDC transmission system is simulated by the simulation software PSCAD/EMTDC linked to Matlab/Simulink, demonstrating the good performances of this new hybrid PWM technology. The theory analyses and simulation results show that this new hybrid PWM technology has great potentiality in the application of VSC-HVDC projects in future.