CAJ | 학술논문

针对中点钳位型三电平变换器的故障和保护进行研究,主要讨论系统的单相接地故障和电力电子器件短路故障。单相接地故障会引起变换器直流母线中点接地阻抗上的电压明显变化,提出一种通过检测接地阻抗电压从而检测系统接地故障的方法。变换器桥臂内侧电力电子器件的短路可以导致直流母线电容电压的不平衡,会出现电容电压的翻倍现象,须采取措施保护直流母线电容和电力电子器件。在分析电压翻倍现象产生原因的基础上,提出了抑制电容电压翻倍的方法。对以上两种故障状态的检测和保护进行了仿真和试验验证,仿真和试验结果验证了所提出方法的有效性。
침대중점겸위형삼전평변환기적고장화보호진행연구,주요토론계통적단상접지고장화전력전자기건단로고장。단상접지고장회인기변환기직류모선중점접지조항상적전압명현변화,제출일충통과검측접지조항전압종이검측계통접지고장적방법。변환기교비내측전력전자기건적단로가이도치직류모선전용전압적불평형,회출현전용전압적번배현상,수채취조시보호직류모선전용화전력전자기건。재분석전압번배현상산생원인적기출상,제출료억제전용전압번배적방법。대이상량충고장상태적검측화보호진행료방진화시험험증,방진화시험결과험증료소제출방법적유효성。
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.