The self-adaption STATCOM and line commutation converter (SLCC) system based on the static var generator and filter (SVF) utilizes the compensation capability of the SVF to reduce the commutation process’s dependence on the AC grid, thereby enhancing the SLCC’s ability to resist commutation failure. However, existing SLCC control strategies have not fully considered the boundary conditions for the safe and stable operation of the SVF (i.e., the SVF withstand capability), which limits or even deteriorates the ability of the SVF to provide commutation support for the SLCC under AC grid voltage fault conditions. To address this issue, this paper first analyzes the current and voltage limit boundaries of the SVF in the SLCC system from the perspective of SVF device stress, revealing the mechanism of SVF withstand capability exceedance under fault conditions. Based on this analysis, a voltage feedforward control strategy that accounts for the SVF withstand capability is proposed. This strategy accelerates the dynamic response of the SVF under fault conditions and enhances the SLCC’s ability to resist commutation failure, while strictly avoiding the risks of SVF current and voltage exceedance, thereby ensuring the SVF operates within its withstand capability boundaries and improving support security under fault conditions. Furthermore, based on the SVF withstand capability boundaries, the commutation margin required to maintain safe commutation for the SLCC is calculated, and the SLCC inversion angle is dynamically adjusted accordingly. This achieves coordinated control between the SLCC and the SVF, preventing SVF blocking due to exceeding its withstand capability and ensuring safe commutation of the SLCC. Simulation results verify that the proposed strategy can simultaneously achieve non-blocking operation of the SVF and safe commutation of the SLCC.
Mao et al. (Thu,) studied this question.