目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态...目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态变量易发生大范围变化,暂态稳定性问题突出。Lyapunov方法是分析暂态稳定性问题的常用方法,但在直流微电网领域中缺少指导构建Lyapunov函数的通用策略,很难直接进行应用。此外,为了提高稳定性,亟待开展以提升暂态稳定性为导向的控制参数优化设计研究。针对以上问题,针对直流微电网系统,考虑DC-DC变换器控制环路,基于平方和(sum of squares,SOS)规划方法开展暂态稳定域估计与参数优化研究,首先,通过设计SOS优化问题,改进传统拓展内部算法求解并获得最大化Lyapunov函数水平集实现对系统稳定域的估计,通过与系统实际稳定域进行对比,验证了所提方法的准确性,与其他现有方法估计的稳定域相比,所提方法保守性大幅降低。随后,基于SOS规划,以拓展稳定域为目标,对电压控制环路参数进行优化。最后,硬件在环仿真实验结果表明,采用优化控制参数后,直流微电网系统稳定域得到扩展,抗扰动能力有效提升,暂态稳定性进一步增强。展开更多
Background: In Togo, the maternal mortality rate in 2017 was estimated at 396/100,000 live births. Maternal death before admission is an increasingly growing phenomenon in the gynecology-obstetrics clinic of the CHU S...Background: In Togo, the maternal mortality rate in 2017 was estimated at 396/100,000 live births. Maternal death before admission is an increasingly growing phenomenon in the gynecology-obstetrics clinic of the CHU SO. No epidemiological data is available on the subject. Objective: Determine the epidemiological and etiological profiles of a pregnant, parturient, or woman who has given birth dead before or within 10 minutes of her admission. Methods: This was a descriptive cross-sectional study from January 1, 2014, to December 31, 2021. All maternal deaths occurring before admission and within 10 minutes of admission to the clinic were included in the study of gynecology and obstetrics at CHU SO. The data were processed by Epi info version 7 software. Results: In total, 654 maternal deaths, including 153 maternal deaths before admission, were recorded, corresponding to 23.4% of all maternal deaths. The median age was 30.2 years. 37.2% of women were uneducated. 41.2% were resellers. 79.1% of women were cohabiting. 47.1% of women had performed less than 3 ANC. 43.8% of the women who died had completed their ANC in a medical center. 54.3% by a midwife, 37.3% by unqualified personnel. 62.7% of deaths occurred postpartum and 36.3% during pregnancy. 79.1% were referrals. 88.9% of the women who died arrived in a non-medical taxi car. Among the 57 patients who died during their pregnancy, 40.3% were carrying a pregnancy of 28 to 36 weeks, and 36.3% were full-term pregnancies. Among the 96 women who died postpartum, 93.3% had given birth vaginally. Among the 121 referrals, 34.7% came from a birthing center, 56.2% were referred by a state midwife and 30.6% by unqualified personnel;46.3% were referred without a reference form, 94.3% were referred without venous access. In 10.7%, the reason for evacuation was bleeding from the delivery, with an average evacuation time of one-hour 5minutes. 60.3% of women who died had an evacuation delay of more than one hour. 94.8% of patients died of direct obstetric causes, including immediate postpartum hemorrhage in 60.1% of cases. Conclusion: Deaths before admission constitute an increasingly growing problem at CHU SO. A late referral is a determining factor in maternal deaths before admission.展开更多
文摘目前,直流微电网在全球范围内快速发展,开展充分的稳定性分析工作是其稳定运行的前提。伴随着大量电力电子装置的接入,相较于传统电网,直流微电网系统等效惯性不足,在经历电网故障、电压暂降或恒功率负载接入接出等大扰动场景后,其状态变量易发生大范围变化,暂态稳定性问题突出。Lyapunov方法是分析暂态稳定性问题的常用方法,但在直流微电网领域中缺少指导构建Lyapunov函数的通用策略,很难直接进行应用。此外,为了提高稳定性,亟待开展以提升暂态稳定性为导向的控制参数优化设计研究。针对以上问题,针对直流微电网系统,考虑DC-DC变换器控制环路,基于平方和(sum of squares,SOS)规划方法开展暂态稳定域估计与参数优化研究,首先,通过设计SOS优化问题,改进传统拓展内部算法求解并获得最大化Lyapunov函数水平集实现对系统稳定域的估计,通过与系统实际稳定域进行对比,验证了所提方法的准确性,与其他现有方法估计的稳定域相比,所提方法保守性大幅降低。随后,基于SOS规划,以拓展稳定域为目标,对电压控制环路参数进行优化。最后,硬件在环仿真实验结果表明,采用优化控制参数后,直流微电网系统稳定域得到扩展,抗扰动能力有效提升,暂态稳定性进一步增强。
文摘Background: In Togo, the maternal mortality rate in 2017 was estimated at 396/100,000 live births. Maternal death before admission is an increasingly growing phenomenon in the gynecology-obstetrics clinic of the CHU SO. No epidemiological data is available on the subject. Objective: Determine the epidemiological and etiological profiles of a pregnant, parturient, or woman who has given birth dead before or within 10 minutes of her admission. Methods: This was a descriptive cross-sectional study from January 1, 2014, to December 31, 2021. All maternal deaths occurring before admission and within 10 minutes of admission to the clinic were included in the study of gynecology and obstetrics at CHU SO. The data were processed by Epi info version 7 software. Results: In total, 654 maternal deaths, including 153 maternal deaths before admission, were recorded, corresponding to 23.4% of all maternal deaths. The median age was 30.2 years. 37.2% of women were uneducated. 41.2% were resellers. 79.1% of women were cohabiting. 47.1% of women had performed less than 3 ANC. 43.8% of the women who died had completed their ANC in a medical center. 54.3% by a midwife, 37.3% by unqualified personnel. 62.7% of deaths occurred postpartum and 36.3% during pregnancy. 79.1% were referrals. 88.9% of the women who died arrived in a non-medical taxi car. Among the 57 patients who died during their pregnancy, 40.3% were carrying a pregnancy of 28 to 36 weeks, and 36.3% were full-term pregnancies. Among the 96 women who died postpartum, 93.3% had given birth vaginally. Among the 121 referrals, 34.7% came from a birthing center, 56.2% were referred by a state midwife and 30.6% by unqualified personnel;46.3% were referred without a reference form, 94.3% were referred without venous access. In 10.7%, the reason for evacuation was bleeding from the delivery, with an average evacuation time of one-hour 5minutes. 60.3% of women who died had an evacuation delay of more than one hour. 94.8% of patients died of direct obstetric causes, including immediate postpartum hemorrhage in 60.1% of cases. Conclusion: Deaths before admission constitute an increasingly growing problem at CHU SO. A late referral is a determining factor in maternal deaths before admission.
