Reducing the vulnerability of a platform,i.e.,the risk of being affected by hostile objects,is of paramount importance in the design process of vehicles,especially aircraft.A simple and effective way to decrease vulne...Reducing the vulnerability of a platform,i.e.,the risk of being affected by hostile objects,is of paramount importance in the design process of vehicles,especially aircraft.A simple and effective way to decrease vulnerability is to introduce protective structures to intercept and possibly stop threats.However,this type of solution can lead to a significant increase in weight,affecting the performance of the aircraft.For this reason,it is crucial to study possible solutions that allow reducing the vulnerability of the aircraft while containing the increase in structural weight.One possible strategy is to optimize the topology of protective solutions to find the optimal balance between vulnerability and the weight of the added structures.Among the many optimization techniques available in the literature for this purpose,multiobjective genetic algorithms stand out as promising tools.In this context,this work proposes the use of a in-house software for vulnerability calculation to guide the process of topology optimization through multi-objective genetic algorithms,aiming to simultaneously minimize the weight of protective structures and vulnerability.In addition to the use of the in-house software,which itself represents a novelty in the field of topology optimization of structures,the method incorporates a custom mutation function within the genetic algorithm,specifically developed using a graph-based approach to ensure the continuity of the generated structures.The tool developed for this work is capable of generating protections with optimized layouts considering two different types of impacting objects,namely bullets and fragments from detonating objects.The software outputs a set of non-dominated solutions describing different topologies that the user can choose from.展开更多
处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检...处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。展开更多
针对模块化多电平换流器型高压直流输电(modular multilevel converter-high voltage direct current,MMC-HVDC)系统,提出了一种创新的换流器桥臂保护方法。首先,分析了在换流器单桥臂接地以及单相桥臂间接地情况下电流的流通路径,构建...针对模块化多电平换流器型高压直流输电(modular multilevel converter-high voltage direct current,MMC-HVDC)系统,提出了一种创新的换流器桥臂保护方法。首先,分析了在换流器单桥臂接地以及单相桥臂间接地情况下电流的流通路径,构建了等值电路,并推导了换流器闭锁前后桥臂电流的表达式。基于此,剖析了故障后三相桥臂电流之和的独有特征,提出了通过检测三相桥臂和电流的基频分量是否为零来区分桥臂内部故障与外部故障的保护策略。鉴于现有桥臂保护方法无法有效应对换流器单相桥臂间短路的问题,进一步研究了此类短路情况下的特性,发现故障相上、下桥臂电流仅包含基频分量而不含直流分量,从而制定了相应的动作判据。将三相桥臂和电流保护与单相桥臂间短路保护判据进行,能够全面识别换流器桥臂上发生的各种故障,丰富和完善了换流器桥臂的保护原理。最终,通过在MATLAB/SimulinK中搭建双极MMC-HVDC系统仿真模型验证了所提出保护方法的有效性和可靠性。展开更多
文摘Reducing the vulnerability of a platform,i.e.,the risk of being affected by hostile objects,is of paramount importance in the design process of vehicles,especially aircraft.A simple and effective way to decrease vulnerability is to introduce protective structures to intercept and possibly stop threats.However,this type of solution can lead to a significant increase in weight,affecting the performance of the aircraft.For this reason,it is crucial to study possible solutions that allow reducing the vulnerability of the aircraft while containing the increase in structural weight.One possible strategy is to optimize the topology of protective solutions to find the optimal balance between vulnerability and the weight of the added structures.Among the many optimization techniques available in the literature for this purpose,multiobjective genetic algorithms stand out as promising tools.In this context,this work proposes the use of a in-house software for vulnerability calculation to guide the process of topology optimization through multi-objective genetic algorithms,aiming to simultaneously minimize the weight of protective structures and vulnerability.In addition to the use of the in-house software,which itself represents a novelty in the field of topology optimization of structures,the method incorporates a custom mutation function within the genetic algorithm,specifically developed using a graph-based approach to ensure the continuity of the generated structures.The tool developed for this work is capable of generating protections with optimized layouts considering two different types of impacting objects,namely bullets and fragments from detonating objects.The software outputs a set of non-dominated solutions describing different topologies that the user can choose from.
文摘处于改建阶段的智能变电站采样模式复杂,继电保护装置难以发现采样回路轻微异常,导致回路隐患暴露时间严重滞后。针对上述问题,分析改建时期智能变电站的采样模式和二次设备配置情况,提出基于同源录波数据比对的继电保护采样回路异常检测方法。首先,利用双向编码器表征(bidirectional encoder representations from transformers,BERT)语言模型与余弦相似度算法,实现同源录波数据的通道匹配。然后,利用重采样技术和曼哈顿距离完成波形的采样频率统一与时域对齐。最后,基于动态时间规整(dynamic time warping,DTW)算法提出改进算法,并结合采样点偏移量共同设置采样回路的异常判据。算例分析表明,该方法可以完成录波数据的同源通道匹配,实现波形的一致性对齐,并且相比于传统DTW算法,改进DTW算法对异常状态识别的灵敏性和准确性更高。根据异常判据能够有效检测继电保护采样回路的异常状态,确保了智能变电站的安全可靠运行。
基金国家自然科学基金(62272077,72301050)重庆市教委科技重大项目(KJZD-M202400604)资助+1 种基金the Natural ScienceFoundation of Chongqing,China(No.cstc2021jcyj msxmX0557)the MOE Layout Foundation of Humanities and Social Sciences,China(No.20YJAZH102).
文摘针对模块化多电平换流器型高压直流输电(modular multilevel converter-high voltage direct current,MMC-HVDC)系统,提出了一种创新的换流器桥臂保护方法。首先,分析了在换流器单桥臂接地以及单相桥臂间接地情况下电流的流通路径,构建了等值电路,并推导了换流器闭锁前后桥臂电流的表达式。基于此,剖析了故障后三相桥臂电流之和的独有特征,提出了通过检测三相桥臂和电流的基频分量是否为零来区分桥臂内部故障与外部故障的保护策略。鉴于现有桥臂保护方法无法有效应对换流器单相桥臂间短路的问题,进一步研究了此类短路情况下的特性,发现故障相上、下桥臂电流仅包含基频分量而不含直流分量,从而制定了相应的动作判据。将三相桥臂和电流保护与单相桥臂间短路保护判据进行,能够全面识别换流器桥臂上发生的各种故障,丰富和完善了换流器桥臂的保护原理。最终,通过在MATLAB/SimulinK中搭建双极MMC-HVDC系统仿真模型验证了所提出保护方法的有效性和可靠性。
