A Cascaded H-bridge Hybrid SVG in LCC-HVDC Applied Research

Aiming at the problem that the current grid commutated converter high voltage direct current (LCC-HVDC) system needs to be equipped with a large number of capacitor banks and AC filter banks, the floor space is too large. The hybrid static var generator (SVG) is proposed to be connected to the AC bus of the LCC-HVDC system, aiming to achieve the functions of reactive power compensation and harmonic filtering. It can effectively reduce the investment cost. This paper first analyzes the basic working principle of the hybrid SVG based on cascaded H-bridges, and makes a reasonable design of the LC parameters. Then, the reactive current and harmonic current of the system are detected and tracked. On this basis, a coordinated control strategy of the LCC-HVDC system and the hybrid SVG is proposed to stabilize the delivery of DC power. Finally, a simulation model is built in PSCAD/EMTDC for verification.