Background：Premature ovarian failure （POF） is a disease that affects female fertility but has few effective treatments.Ovarian reserve function plays an important role in female fertility.Recent studies have report...Background：Premature ovarian failure （POF） is a disease that affects female fertility but has few effective treatments.Ovarian reserve function plays an important role in female fertility.Recent studies have reported that hydrogen can protect male fertility.Therefore,we explored the potential protective effect of hydrogen-rich water on ovarian reserve function through a mouse immune POF model.Methods：To set up immune POF model,fifty female BALB/c mice were randomly divided into four groups：Control （mice consumed normal water,n =10）,hydrogen （mice consumed hydrogen-rich water,n =10）,model （mice were immunized with zona pellucida glycoprotein 3 [ZP3] and consumed normal water,n =15）,and model-hydrogen （mice were immunized with ZP3 and consumed hydrogen-rich water,n =15） groups.After 5 weeks,mice were sacrificed.Serum anti-M＆#252;llerian hormone （AMH） levels,granulosa cell （GC） apoptotic index （AI）,B-cell leukemia/lymphoma 2 （Bcl-2）,and BCL2-associated X protein （Bax） expression were examined.Analyses were performed using SPSS 17.0 （SPSS Inc.,Chicago,IL,USA） software.Results：Immune POF model,model group exhibited markedly reduced serum AMH levels compared with those of the control group （5.41 ± 0.91 ng/ml vs.16.23 ± 1.97 ng/ml,P =0.033） and the hydrogen group （19.65 ± 7.82 ng/ml,P =0.006）.The model-hydrogen group displayed significantly higher AMH concentrations compared with that of the model group （15.03 ± 2.75 ng/ml vs.5.41 ± 0.91 ng/ml,P =0.021）.The GC AI was significantly higher in the model group （21.30 ± 1.74%） than those in the control （7.06 ± 0.27%）,hydrogen （5.17 ± 0.41%）,and model-hydrogen groups （11.24 ± 0.58%） （all P 〈 0.001）.The GC AI was significantly higher in the model-hydrogen group compared with that of the hydrogen group （1 1.24 ± 0.58% vs.5.1 7 ± 0.41%,P =0.021）.Compared with those of the model group,ovarian tissue Bcl-2 levels increased （2.18 ± 0.30 vs.3.01 ± 0.33,P =0.045） and the Bax/Bcl-2 ratio decreased in the model-hydrogen group.Conclusions：Hydrogen-rich water may improve serum AMH levels and reduce ovarian GC apoptosis in a mouse immune POF model induced by ZP3.展开更多
This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indi...This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indicates that the local CF is not influenced by MIIF,whereas this paper concludes that both the local CF and concurrent CF are influenced by MIIF.The ability of remote converter to work under reduced reactive power enables its feature to support local converter via inter-connection link.The MIIF measures the strength of electrical connectivity between converters.Higher MIIF gives a clearer path to remote converter to support local converter,but at the same time,it provides an easy path to local converter to disturb remote converter under local fault.The presence of nearby converter increases the local commutation failure immunity index(CFII)while reducing concurrent CFII.Higher MIIF causes reactive power support to flow from remote converter to local converter,which reduces the chances of CF.A mathematical approximation to calculate the increase in local CFII for multi-infeed HVDC configurations is also proposed.A power flow approach is used to model the relation between MIIF and reactive power support from remote end.The local and concurrent CFIIs are found to be inverse to each other over MIIF;therefore,it is recommended that there is an optimal value of MIIF for all converters in close electric proximity to maintain CFII at a certain level.The numerical results of established model are compared with PSCAD/EMTDC simulations.The simulation results show the details of the influence of MIIF on local CF and concurrent CF of multi-infeed HVDC,which validates the analysis presented.展开更多
Large-scale synchronous condenser (LSC) has a broad application prospect in China's ultra-high voltage direct current (UHVDC) to provide dynamic reactive power. Loss of excitation (LOE) is an important grid-relate...Large-scale synchronous condenser (LSC) has a broad application prospect in China's ultra-high voltage direct current (UHVDC) to provide dynamic reactive power. Loss of excitation (LOE) is an important grid-related fault of LSC, resulting in uncontrolled reactive power consumption. However, due to the un obvious fault feature and UHVDC's diverse reactive power demands, LSC's LOE protection faces challenges in criterion and action mode configurations. Thus, this paper proposes a complete LOE protection strategy for the LSC used in UHVDC, including effective criterion and proper action mode. First, the defect of existing reverse reactive power-based protection is presented through an in-depth analysis of the LOE LSC's reactive power behavior. Then, excitation current difference between the measured value and equivalent actual value is identified as the new fault feature. Compared with existing reverse reactive power features which also appear in healthy LSC's leading phase conditions, this current difference feature only appears in the LO E process and thus is more typical. Since actual excitation current is unmeasurable in practice, an estimation model is built and validated by experiment and simulation. Moreover, the novel LOE protection strategy including current-based criterion and improved action mode is proposed. Through comparative simulation studies in PSCADIEMTDC, the novel protection exhibits superior performances compared to existing protection in LOE detection and commutation failure immunity improvement, as well as overvoltage suppression.展开更多
文摘Background：Premature ovarian failure （POF） is a disease that affects female fertility but has few effective treatments.Ovarian reserve function plays an important role in female fertility.Recent studies have reported that hydrogen can protect male fertility.Therefore,we explored the potential protective effect of hydrogen-rich water on ovarian reserve function through a mouse immune POF model.Methods：To set up immune POF model,fifty female BALB/c mice were randomly divided into four groups：Control （mice consumed normal water,n =10）,hydrogen （mice consumed hydrogen-rich water,n =10）,model （mice were immunized with zona pellucida glycoprotein 3 [ZP3] and consumed normal water,n =15）,and model-hydrogen （mice were immunized with ZP3 and consumed hydrogen-rich water,n =15） groups.After 5 weeks,mice were sacrificed.Serum anti-M＆#252;llerian hormone （AMH） levels,granulosa cell （GC） apoptotic index （AI）,B-cell leukemia/lymphoma 2 （Bcl-2）,and BCL2-associated X protein （Bax） expression were examined.Analyses were performed using SPSS 17.0 （SPSS Inc.,Chicago,IL,USA） software.Results：Immune POF model,model group exhibited markedly reduced serum AMH levels compared with those of the control group （5.41 ± 0.91 ng/ml vs.16.23 ± 1.97 ng/ml,P =0.033） and the hydrogen group （19.65 ± 7.82 ng/ml,P =0.006）.The model-hydrogen group displayed significantly higher AMH concentrations compared with that of the model group （15.03 ± 2.75 ng/ml vs.5.41 ± 0.91 ng/ml,P =0.021）.The GC AI was significantly higher in the model group （21.30 ± 1.74%） than those in the control （7.06 ± 0.27%）,hydrogen （5.17 ± 0.41%）,and model-hydrogen groups （11.24 ± 0.58%） （all P 〈 0.001）.The GC AI was significantly higher in the model-hydrogen group compared with that of the hydrogen group （1 1.24 ± 0.58% vs.5.1 7 ± 0.41%,P =0.021）.Compared with those of the model group,ovarian tissue Bcl-2 levels increased （2.18 ± 0.30 vs.3.01 ± 0.33,P =0.045） and the Bax/Bcl-2 ratio decreased in the model-hydrogen group.Conclusions：Hydrogen-rich water may improve serum AMH levels and reduce ovarian GC apoptosis in a mouse immune POF model induced by ZP3.
基金This work was supported by science and technology project of China Southern Power Grid(No.ZBKJXM20180104).
文摘This paper provides a comprehensive analysis of local and concurrent commutation failure(CF)of multi-infeed high-voltage direct current(HVDC)system considering multi-infeed interaction factor(MIIF).The literature indicates that the local CF is not influenced by MIIF,whereas this paper concludes that both the local CF and concurrent CF are influenced by MIIF.The ability of remote converter to work under reduced reactive power enables its feature to support local converter via inter-connection link.The MIIF measures the strength of electrical connectivity between converters.Higher MIIF gives a clearer path to remote converter to support local converter,but at the same time,it provides an easy path to local converter to disturb remote converter under local fault.The presence of nearby converter increases the local commutation failure immunity index(CFII)while reducing concurrent CFII.Higher MIIF causes reactive power support to flow from remote converter to local converter,which reduces the chances of CF.A mathematical approximation to calculate the increase in local CFII for multi-infeed HVDC configurations is also proposed.A power flow approach is used to model the relation between MIIF and reactive power support from remote end.The local and concurrent CFIIs are found to be inverse to each other over MIIF;therefore,it is recommended that there is an optimal value of MIIF for all converters in close electric proximity to maintain CFII at a certain level.The numerical results of established model are compared with PSCAD/EMTDC simulations.The simulation results show the details of the influence of MIIF on local CF and concurrent CF of multi-infeed HVDC,which validates the analysis presented.
文摘Large-scale synchronous condenser (LSC) has a broad application prospect in China's ultra-high voltage direct current (UHVDC) to provide dynamic reactive power. Loss of excitation (LOE) is an important grid-related fault of LSC, resulting in uncontrolled reactive power consumption. However, due to the un obvious fault feature and UHVDC's diverse reactive power demands, LSC's LOE protection faces challenges in criterion and action mode configurations. Thus, this paper proposes a complete LOE protection strategy for the LSC used in UHVDC, including effective criterion and proper action mode. First, the defect of existing reverse reactive power-based protection is presented through an in-depth analysis of the LOE LSC's reactive power behavior. Then, excitation current difference between the measured value and equivalent actual value is identified as the new fault feature. Compared with existing reverse reactive power features which also appear in healthy LSC's leading phase conditions, this current difference feature only appears in the LO E process and thus is more typical. Since actual excitation current is unmeasurable in practice, an estimation model is built and validated by experiment and simulation. Moreover, the novel LOE protection strategy including current-based criterion and improved action mode is proposed. Through comparative simulation studies in PSCADIEMTDC, the novel protection exhibits superior performances compared to existing protection in LOE detection and commutation failure immunity improvement, as well as overvoltage suppression.
