Fault Crossing Control Method Based On SSPFM-MPC

MMC-HVDC can meet the needs of different capacity voltage level,only the number of sub-modules can be increased,with the development of large-capacity high,the harmonics will be reduced,do not increase Filter device,but its DC fault crossing problem has been difficult to study.The working principle and the working mode of the HBSM,FBSM and CDSM are described in detail.The common DC fault crossing modulation strategy is analyzed,and the formula derivation and analysis are carried out for CPS-SPWM and NLM.Based on the structure of HBSM sub-module,a sub-module capable of fault traversing capability is proposed,and its control strategy is designed.NLM modulation strategy,based on the control of the sub-module capacitor voltage balance,detailing the traditional bubble method of the capacitor voltage fluctuation principle,when the system level increases,the sorting index increases,in order to system failure through the smooth And the SSPFM algorithm is introduced to realize the sequencing of the sub-module capacitor voltage.At the same time,the MPC structure is used instead of the current loop on the basis of the traditional double PI structure due to the non-uniformity of the parameters of the three-phase line structure.Capacitor voltage,interphase circulation and AC side current parameters combined to construct the most function,so that the whole system to achieve the best DC fault through the run.After confirming that the MMC-HVDC system based on SSPFM-MPC DC fault traversing capability can run normally,the fault type that is converter station failure and DC side fault are briefly introduced,and the corresponding fault is simulated and the protection measures are put forward,The converter station failure generally take off the exchange side of the circuit breaker,and the two ends of the power supply system bipolar transmission unipolar ground fault,can still live running,you can delay the operation of protection,simulation experiments proved that it has a good fault crossing ability.