Interruption method for commutation failure caused cascading reaction of HVDC with wind farm integration under grid fault

Abstract

Line-commuted converter based high voltage direct current (LCC-HVDC) is a typical mode for wind power transmission. The fault of the receiving-end grid of LCC-HVDC can easily lead to the commutation failure at the inverter station. Improper controls during the recovery process of first commutation failure may cause the subsequent commutation failure, and lead to the high voltage ride through of wind generators at the sending-end grid. The regional and inter-regional cascading reactions are produced by commutation failure. Existing researches severally focus on control of suppressing subsequent commutation failure or overvoltage. The demand for commutation failure recovery of the inverter and overvoltage suppression at the sending-end grid cannot be satisfied simultaneously, and may even aggravate the cascading process. The stability of the power system will be threatened. Therefore, the new idea of feasible power region and adaptive current control of inverter station is proposed to interrupt commutation failure caused cascading reaction. The feasible ranges of DC current to avoid subsequent commutation failure and overvoltage are derived. The feasible power region is modeled by the active power and exchanged reactive power of inverter station. The principle of interrupting commutation failure caused cascading reaction based on adaptive current control of inverter station is proposed. Then, the command value calculation and implementation method of adaptive current control are further proposed. Finally, the performance of the proposed control method and voltage-dependent current order limiter (VDCOL) control is compared based on the CIGRE LCC-HVDC standard system, and the effectiveness of theoretical research is verified by the simulation results.