With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier un...With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.展开更多
A monolithic integrated full-wave bridge rectifier consisted of horizontal Schottky-barrier diodes(SBD)is prepared based on 100 nm ultra-thin β-Ga_(2)O_(3)and demonstrated the solar-blind UV(SUV)light-modulated chara...A monolithic integrated full-wave bridge rectifier consisted of horizontal Schottky-barrier diodes(SBD)is prepared based on 100 nm ultra-thin β-Ga_(2)O_(3)and demonstrated the solar-blind UV(SUV)light-modulated characteristics.Under SUV light illumination,the rectifier has the excellent full-wave rectification characteristics for the AC input signals of 5,12,and 24 V with different frequencies.Further,experimental results confirmed the feasibility of continuously tuning the rectified output through SUV light-encoding.This work provides valuable insights for the development of optically programmable Ga_(2)O_(3)ACDC converters.展开更多
带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解...带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解电容。电解电容存在寄生参数等效串联电阻(equivalent series resistance,ESR),会引起输出电压波形畸变及电压大小的变化。为此,该文提出一种考虑滤波电容寄生参数ESR的双三相整流发电机带脉冲负载的瞬时电压计算方法。首先,建立考虑滤波电容寄生参数ESR的带脉冲功率负载的双三相整流发电机等效瞬态数学模型;其次,通过双三相整流发电机瞬态有限元仿真同负载突变实验进行对比,验证所提出的考虑滤波电容寄生参数ESR的双三相整流发电机等效模型负载突变的瞬时电压计算方法的必要性与可行性;最后,分析滤波电容C及其寄生参数ESR对双三相整流发电机直流侧电压的影响。结果表明,建立的等效模型具有较高的准确性,同时,表明考虑滤波电容寄生参数ESR对整流发电机直流测电压的研究对提高整个直流供电系统电能质量具有重要意义。展开更多
基金funded by the Science and Technology Projects of State Grid Zhejiang Electric Power Co.,Ltd.(5211DS24000G).
文摘With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.
基金supported by Natural Science Basic Research Program of Shaanxi Province of China(Grant No.2023JCYB574)National Natural Science Foundation of China(Grant No.62204203)。
文摘A monolithic integrated full-wave bridge rectifier consisted of horizontal Schottky-barrier diodes(SBD)is prepared based on 100 nm ultra-thin β-Ga_(2)O_(3)and demonstrated the solar-blind UV(SUV)light-modulated characteristics.Under SUV light illumination,the rectifier has the excellent full-wave rectification characteristics for the AC input signals of 5,12,and 24 V with different frequencies.Further,experimental results confirmed the feasibility of continuously tuning the rectified output through SUV light-encoding.This work provides valuable insights for the development of optically programmable Ga_(2)O_(3)ACDC converters.
文摘带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解电容。电解电容存在寄生参数等效串联电阻(equivalent series resistance,ESR),会引起输出电压波形畸变及电压大小的变化。为此,该文提出一种考虑滤波电容寄生参数ESR的双三相整流发电机带脉冲负载的瞬时电压计算方法。首先,建立考虑滤波电容寄生参数ESR的带脉冲功率负载的双三相整流发电机等效瞬态数学模型;其次,通过双三相整流发电机瞬态有限元仿真同负载突变实验进行对比,验证所提出的考虑滤波电容寄生参数ESR的双三相整流发电机等效模型负载突变的瞬时电压计算方法的必要性与可行性;最后,分析滤波电容C及其寄生参数ESR对双三相整流发电机直流侧电压的影响。结果表明,建立的等效模型具有较高的准确性,同时,表明考虑滤波电容寄生参数ESR对整流发电机直流测电压的研究对提高整个直流供电系统电能质量具有重要意义。
