Non-characteristic Harmonic Analysis of CLCC-HVDC System

State Grid Shanghai Municipal Electric Power Company proposes a new type of controllable grid phase shifting converter CLCC, which adopts a hybrid design of converter valves to improve the stability of high-voltage direct current transmission system operation. Aiming at the problem of non-characteristic harmonic currents generated by controllable grid phase-change converter, firstly, we theoretically introduce the principle of CLCC model, analyze the reasons for the generation of non-characteristic harmonic currents in the system, and put forward the scheme of filtering by improving the existing STATCOM device. PSCAD software is used as a platform to establish a simulation model and design cases to calculate and analyze the non-characteristic harmonic currents. The simulation results show that when the converter trigger angle is unbalanced, it has the greatest influence on the system net-side non-characteristic harmonic current, and the proposed STATCOM improvement measures have better non-characteristic harmonic suppression effect.