针对故障情景下风电场等值模型精度偏低的问题,提出了一种考虑低压穿越(low voltage ride through,LVRT)功率特性的风电场多机聚合辨识等值建模方法。首先,基于风电机组LVRT期间有功功率动态特性的典型差异对风电场进行初次分群。其次,...针对故障情景下风电场等值模型精度偏低的问题,提出了一种考虑低压穿越(low voltage ride through,LVRT)功率特性的风电场多机聚合辨识等值建模方法。首先,基于风电机组LVRT期间有功功率动态特性的典型差异对风电场进行初次分群。其次,采用基于动态时间规整(dynamic time warping,DTW)度量的多路谱聚类(Ng-Jordan Weiss,NJW)算法实现机群的二次划分,得到最终两阶段分群结果。然后,针对聚合所得的风电场多机等值模型,采用参数灵敏度分析方法来确定需要优化的重点参数,以各参数聚合值为初值,同时结合单机分步辨识、多机依次辨识以及等值阻抗辨识3种策略,实现风电场整体等值参数的优化。最后,对比了不同方法的拟合曲线及等值误差,结果表明所提方法有效提高了等值模型的精确性与适应性。展开更多
Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observati...Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observations reveal that bottom currents are strongly influenced by the topography, being along valley axis or isobaths. Power density spectrum analysis shows that all the currents have significant peaks at diurnal and semi-diurnal frequencies. Diurnal energy is dominant at the open slope site, which is consistent with many previous studies. However, at the site inside the valley the semi-diurnal energy dominates, although the distance between the two sites of observation is quite small （11 kin） compared to a typical horizontal first-mode internal tide wavelength （200 km）. We found this phenomenon is caused by the focusing of internal waves of certain frequencies in the valley. The inertial peak is found only at the open slope site in the first deployment but missing at the inside valley site and the rest of the de- ployments. Monthly averaged residual currents reveal that the near-bottom currents on the slope flow southwestward throughout the year except in August and September, 2013, from which we speculate that this is a result of the interaction between a mesoscale eddy and the canyon/sag topography. Currents inside the valley within about 10mab basically flow along slope and in the layers above the 10mab the currents are northwestward, that is, from the deep ocean to the shelf. The monthly mean current vectors manifest an Ek- man layer-like vertical structure at both sites, which rotate counter-clockwise looking from above.展开更多
The muhiyear averaged surface current field and seasonal variability in the Kuroshio and adjacent regions are studied. The data used are trajectories and （1/4） ° latitude by （1/4） ° longitude mean curren...The muhiyear averaged surface current field and seasonal variability in the Kuroshio and adjacent regions are studied. The data used are trajectories and （1/4） ° latitude by （1/4） ° longitude mean currents derived from 323 Argos drifters deployed by Chinese institutions and world ocean circulation experiment from 1979 to 2003. The results show that the Kuroshio surface path adapts well to the western boundary topography and exhibits six great turnings. The branching occurs frequently near anticyclonic turnings rather than near cyclonic ones. In the Luzon Strait, the surface water intrusion into the South China Sea occurs only in fall and winter. The Kuroshio surface path east of Taiwan, China appears nearly as straight lines in summer, fall, and winter, when anticyclonic eddies coexist on its right side; while the path may cyclonically turning in spring when no eddy exists. The Kuroshio intrusion northeast of Taiwan often occurs in fall and winter, but not in summer. The running direction, width and velocity of the middle segment of the Kuroshio surface currents in the East China Sea vary seasonally. The northward intrusion of the Kuroshio surface water southwest of Kyushu occurs in spring and fall, but not in summer. The northmost position of the Kuroshio surface path southwest of Kyushu occurs in fall, but never goes beyond 31 °N. The northward surface current east of the Ryukyu Islands exists only along Okinawa-Amami Islands from spring to fall. In particular, it appears as an arm of an anti- cyclonic eddy in fall.展开更多
The South China Sea （SCS）, in particular the northern SCS, is one of ocean areas where energetic internal solitary waves （ISWs）occur most frequently （Cai et al., 2012; Zheng, 2017）. Based on the re-appearance pe...The South China Sea （SCS）, in particular the northern SCS, is one of ocean areas where energetic internal solitary waves （ISWs）occur most frequently （Cai et al., 2012; Zheng, 2017）. Based on the re-appearance period （RP） at an observation station, Ramp et al.（2004） divided the ISWs into two types：Type-a and Type-b. Type-a ISWs arrive regularly at the same time every day, i.e., the RP is about 24 h, and Type-b ISWs arrive about one hour late every day, i.e., the RP is about 25 h.展开更多
文摘针对故障情景下风电场等值模型精度偏低的问题,提出了一种考虑低压穿越(low voltage ride through,LVRT)功率特性的风电场多机聚合辨识等值建模方法。首先,基于风电机组LVRT期间有功功率动态特性的典型差异对风电场进行初次分群。其次,采用基于动态时间规整(dynamic time warping,DTW)度量的多路谱聚类(Ng-Jordan Weiss,NJW)算法实现机群的二次划分,得到最终两阶段分群结果。然后,针对聚合所得的风电场多机等值模型,采用参数灵敏度分析方法来确定需要优化的重点参数,以各参数聚合值为初值,同时结合单机分步辨识、多机依次辨识以及等值阻抗辨识3种策略,实现风电场整体等值参数的优化。最后,对比了不同方法的拟合曲线及等值误差,结果表明所提方法有效提高了等值模型的精确性与适应性。
基金funded by China National Offshore Oil Corporation (CNOOC)sponsored by the National Natural Science Foundation of China (Nos.41406031 and 41376038)NSFC-Shandong Joint Fund for Marine Science Research Centers (No.U1406404)
文摘Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observations reveal that bottom currents are strongly influenced by the topography, being along valley axis or isobaths. Power density spectrum analysis shows that all the currents have significant peaks at diurnal and semi-diurnal frequencies. Diurnal energy is dominant at the open slope site, which is consistent with many previous studies. However, at the site inside the valley the semi-diurnal energy dominates, although the distance between the two sites of observation is quite small （11 kin） compared to a typical horizontal first-mode internal tide wavelength （200 km）. We found this phenomenon is caused by the focusing of internal waves of certain frequencies in the valley. The inertial peak is found only at the open slope site in the first deployment but missing at the inside valley site and the rest of the de- ployments. Monthly averaged residual currents reveal that the near-bottom currents on the slope flow southwestward throughout the year except in August and September, 2013, from which we speculate that this is a result of the interaction between a mesoscale eddy and the canyon/sag topography. Currents inside the valley within about 10mab basically flow along slope and in the layers above the 10mab the currents are northwestward, that is, from the deep ocean to the shelf. The monthly mean current vectors manifest an Ek- man layer-like vertical structure at both sites, which rotate counter-clockwise looking from above.
基金The National Natural Science Foundations of China under contract Nos40406009,40333030and40706013
文摘The muhiyear averaged surface current field and seasonal variability in the Kuroshio and adjacent regions are studied. The data used are trajectories and （1/4） ° latitude by （1/4） ° longitude mean currents derived from 323 Argos drifters deployed by Chinese institutions and world ocean circulation experiment from 1979 to 2003. The results show that the Kuroshio surface path adapts well to the western boundary topography and exhibits six great turnings. The branching occurs frequently near anticyclonic turnings rather than near cyclonic ones. In the Luzon Strait, the surface water intrusion into the South China Sea occurs only in fall and winter. The Kuroshio surface path east of Taiwan, China appears nearly as straight lines in summer, fall, and winter, when anticyclonic eddies coexist on its right side; while the path may cyclonically turning in spring when no eddy exists. The Kuroshio intrusion northeast of Taiwan often occurs in fall and winter, but not in summer. The running direction, width and velocity of the middle segment of the Kuroshio surface currents in the East China Sea vary seasonally. The northward intrusion of the Kuroshio surface water southwest of Kyushu occurs in spring and fall, but not in summer. The northmost position of the Kuroshio surface path southwest of Kyushu occurs in fall, but never goes beyond 31 °N. The northward surface current east of the Ryukyu Islands exists only along Okinawa-Amami Islands from spring to fall. In particular, it appears as an arm of an anti- cyclonic eddy in fall.
基金The National Science and Technology Major Project of China under contract No.2016ZX05057015the National Natural Science Foundation of China under contract Nos 41376038 and 40406009+3 种基金the NSFC-Shandong Joint Fund for Marine Science Research Centers of China under contract No.U1606405the National Program on Global Change and Air-Sea Interaction of China under contract Nos GASI-03-01-01-02,GASI-02-IND-STSsum and GASI-IPOVAI-01-05the Public Science and Technology Research Funds Projects of Ocean of China under contract No.200905024the National Key Scientific Instrument and Equipment Development Projects of China under contract No.2012YQ12003908
文摘The South China Sea （SCS）, in particular the northern SCS, is one of ocean areas where energetic internal solitary waves （ISWs）occur most frequently （Cai et al., 2012; Zheng, 2017）. Based on the re-appearance period （RP） at an observation station, Ramp et al.（2004） divided the ISWs into two types：Type-a and Type-b. Type-a ISWs arrive regularly at the same time every day, i.e., the RP is about 24 h, and Type-b ISWs arrive about one hour late every day, i.e., the RP is about 25 h.
