Abstract：This paper presents the detection and protection methods uniquely associated with three-level neutral-point-clamped voltage source converters. The line-to-ground fault can cause significant change of dc-link neutral voltage and therefore can be effectively detected and located through monitoring the voltage without extra hardware. The inner device short circuit in the three-level phase-leg can lead to dc-link voltage unbalance and doubling the stress on capacitors and devices, which must be suppressed for the safe operation of the converter. Two methods are proposed to limit the overvoltage. The design of both the ground fault detection and overvoltage limiting is covered in the paper. The schemes are verified through simulation and experiments.
原熙博, 李永东. 中点钳位型三电平变换器两种故障状态的检测和保护[J]. 电工技术学报, 2010, 25(6): 70-76.
Yuan Xibo, Li Yongdong, Wang Fred. Two Fault Detection and Protection Methods for Three-Level Neutral-Point-Clamped Converters. Transactions of China Electrotechnical Society, 2010, 25(6): 70-76.
[1] Lyons J. Innovation IGCT main drives[C]. IEEE Industry Application Society Annual Conference, 1999: 2655-2661. [2] Kolar J W, Zach F C. A novel three-phase utility interface minimizing line current harmonics of high-power telecommunications rectifier modules [J]. IEEE Transactions on Industrial Electronics, 1997, 44 (4): 456-467. [3] Nabae A, Takahashi I, Akagi A. A new neutral-point clamped PWM inverter[J]. IEEE Transactions on Industry Applications, 1981, 19(5): 518-523. [4] Sinha G, Hochgraf C, Lassctcr R H, et al. Fault protection in a multilevel inverter implementation of a static condenser[C]. IEEE Industry Application Society Annual Conference, 1995, 3: 2557-2564. [5] Hu Zhaoqing, Mao Chengxiong, Lu Jiming, et al. Fuse protection of IGCTs against rupture in three- level commutated inverter[C]. International Conference on Power System Technology, 2002, 1: 611-615. [6] Steimer P K, Steinke J K, Gruning H E. A reliable, interface-friendly medium voltage drive based on the robust IGCT and DTC technologies[C]. IEEE Industry Application Society Annual Conference, 1999, 3: 1505-1512. [7] Manoel Eustaquio dos Santos, Braz de J Cardoso Filho. Short circuit and overcurrent protection of IGCT-based three-level NPC inverters[C]. IEEE Power Electronics Specialist Conference, 2004: 2553- 2558. [8] Son Ho In, Kim Tae Jin , Kang Dae Wook, et al. Fault diagnosis and neutral point voltage control when the 3-level inverter faults occur[C]. IEEE Power Electronics Specialist Conference, 2004: 4558-4563. [9] Chen Alian, Hu Lei, Chen Lifeng, et al. A multilevel converter topology with fault-tolerant ability[J]. IEEE Transactions on Power Electronics, 2005, 20(2): 405- 415. [10] Li Shengming, Xu Longya. Strategies of fault tolerant operation for three-level PWM inverters[J]. IEEE Transactions on Power Electronics, 2006, 21(4): 933- 940. [11] Edison R Da Silva, Wellington S Lima, et al. Detection and compensation of switch faults in a three level inverter [C]. IEEE Power Electronics Specialist Conference, 2006, 3: 1-7. [12] Das J C, Richard, Osman H. Grounding of AC and DC low-voltage and medium-voltage drive systems[J]. IEEE Transactions on Industry Application, 1998, 34 (1): 205-216.
2010, Vol. 25 
