适用于光伏直流升压变换器的故障诊断及保护策略

以输入并联输出串联（IPOS）型Boost全桥隔离变换器（BFBIC）为研究对象,针对其内部故障发生后无法迅速定位的问题,提出基于波形积分法的故障诊断策略。该策略通过选取变换器内部固定测量点,基于运行机理分析变换器发生硬故障或直流汇集线路故障时各电气量的波形特征,并通过总结特征规律对故障位置进行识别。针对现有冗余桥臂方案在BFBIC-IPOS上不适用的问题,提出利用冗余升压单元实现内部故障穿越的保护策略。该策略通过更改器件参数及冗余单元备用状态,避免升压单元投切过程中的过流、过压问题。最后,通过PSIM建模仿真,验证故障诊断策略及冗余保护策略的有效性。

FAULT DIAGNOSIS AND PROTECTION STRATEGY FOR PHOTOVOLTAIC DC-DC CONVERTER

Taking the input-parallel output-series（IPOS）type boost full bridge isolated converter（BFBIC）as the research object. Aiming at the problem that its internal fault cannot be located quickly after it occurs,a fault diagnosis strategy based on the waveform integration method is proposed. This strategy selects fixed measuring points inside the converter, analyzes the waveform characteristics of each electrical quantity when the converter has a hard fault or a DC collection line fault based on the operating mechanism, and identifies the fault location by summarizing the characteristic rules. Aiming at the problem that the existing redundant bridge arm scheme is not applicable to BFBIC-IPOS, a protection strategy using redundant boost units to achieve internal fault ride-through is proposed. This strategy avoids over-current and over-voltage problems in the switching process of the boost unit by changing the device parameters and the standby state of the redundant unit. Finally,through PSIM modeling and simulation,the effectiveness of the fault diagnosis strategy and the redundancy protection strategy is verified.