针对经长距离交流海缆送出的海上风电并网谐振问题,首先建立典型设备模型,开展计及海缆容抗特性的谐振机理分析。在此基础上,提出基于高压有源谐振抑制器HARS(high-voltage active resonance suppressor)的海上风电谐振抑制技术。采用...针对经长距离交流海缆送出的海上风电并网谐振问题,首先建立典型设备模型,开展计及海缆容抗特性的谐振机理分析。在此基础上,提出基于高压有源谐振抑制器HARS(high-voltage active resonance suppressor)的海上风电谐振抑制技术。采用降压变+H桥级联型阀组的两级式变换结构,实现220 kV高电压等级可靠并网。基于阻抗重塑思想,提出以网侧电流谐振分量为反馈的谐振阻尼控制策略,并给出阻尼系数和带通中心频率2个关键参数的可行域解析方法。最后,通过仿真和工程实践验证了所提技术的可行性和有效性。展开更多
Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications.The microstructure and corrosion behavior of AZ31Mn-xEr(x=0.1,0.5,1.2)alloys were systematicall...Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications.The microstructure and corrosion behavior of AZ31Mn-xEr(x=0.1,0.5,1.2)alloys were systematically investigated using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray photoelectron spectroscopy(XPS),combined with Tafel polarization and electrochemical impedance spectroscopy(EIS)analyses.The findings showed that the alloying element Er refined the grain structure during solidification by increasing the nucleation rate and forming a secondary phase of Al_(3)Er with Al.The Er and Mg in the matrix co-oxidize to form a dense MgO/Er_(2)O_(3)composite oxide,preventing the formation of loose magnesium hydroxide/basic magnesium carbonate.The trace alloying element Mn interacts with impurities Fe in the magnesium matrix to form an AlFeMn second phase,reducing micro-galvanic corrosion driving force.Electrochemical testing in a 3.5%NaCl solution demonstrated a marked reduction in corrosion rate from 10.46 mm/a(AZ 31 Mn alloy)to 0.44 mm/a(AZ31Mn-1.2Er alloy).This research offers a reference for searching for corrosion-resistant magnesium alloy and degradable medical magnesium alloy materials.展开更多
文摘针对经长距离交流海缆送出的海上风电并网谐振问题,首先建立典型设备模型,开展计及海缆容抗特性的谐振机理分析。在此基础上,提出基于高压有源谐振抑制器HARS(high-voltage active resonance suppressor)的海上风电谐振抑制技术。采用降压变+H桥级联型阀组的两级式变换结构,实现220 kV高电压等级可靠并网。基于阻抗重塑思想,提出以网侧电流谐振分量为反馈的谐振阻尼控制策略,并给出阻尼系数和带通中心频率2个关键参数的可行域解析方法。最后,通过仿真和工程实践验证了所提技术的可行性和有效性。
基金Projects(82171030,81870678)supported by the National Natural Science Foundation of China。
文摘Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications.The microstructure and corrosion behavior of AZ31Mn-xEr(x=0.1,0.5,1.2)alloys were systematically investigated using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray photoelectron spectroscopy(XPS),combined with Tafel polarization and electrochemical impedance spectroscopy(EIS)analyses.The findings showed that the alloying element Er refined the grain structure during solidification by increasing the nucleation rate and forming a secondary phase of Al_(3)Er with Al.The Er and Mg in the matrix co-oxidize to form a dense MgO/Er_(2)O_(3)composite oxide,preventing the formation of loose magnesium hydroxide/basic magnesium carbonate.The trace alloying element Mn interacts with impurities Fe in the magnesium matrix to form an AlFeMn second phase,reducing micro-galvanic corrosion driving force.Electrochemical testing in a 3.5%NaCl solution demonstrated a marked reduction in corrosion rate from 10.46 mm/a(AZ 31 Mn alloy)to 0.44 mm/a(AZ31Mn-1.2Er alloy).This research offers a reference for searching for corrosion-resistant magnesium alloy and degradable medical magnesium alloy materials.
