Mid-and high-frequency resonance(MHFR)is highly likely to occur at the sending end of voltage source con-verter-based ultra-high voltage direct current(VSC-UHVDC)for large-scale renewable energy transmission.It is of ...Mid-and high-frequency resonance(MHFR)is highly likely to occur at the sending end of voltage source con-verter-based ultra-high voltage direct current(VSC-UHVDC)for large-scale renewable energy transmission.It is of great im-portance to investigate the resonance characteristics and the corresponding suppression strategies.Firstly,this paper intro-duces the overall'control scheme of VSC-UHVDC for large-scale renewable energy transmission.Then,the impedance mod-els of VSC under grid-forming control with AC voltage coordi-nated control are established.The mid-and high-frequency im-pedance characteristics of VSC-UHVDC are analyzed.The key factors affecting the impedance characteristics have been re-vealed,including the AC voltage control,the voltage feedfor-ward,the inner current loop,the positive-sequence and nega-tive-sequence independent control(PSNSIC),and the control de-lay.The MHFR characteristics at the sending-end system are analyzed in the whole operation process,including the black start and the normal power transmission operation.An integrat-ed control scheme is proposed to address the MHFR problems.Finally,extensive case studies are conducted on a planned VSC-UHVDC project to verify the theoretical analysis.展开更多
The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor a...The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.展开更多
基于移相控制的双有源桥串联谐振变换器(dual-bridge series resonant converter,DBSRC)在传输功率的快速调控过程中,移相角将发生较大的阶跃变化,导致谐振腔出现大幅度长时间的振荡过程,不仅严重恶化了变换器的动态性能,电路元件也会...基于移相控制的双有源桥串联谐振变换器(dual-bridge series resonant converter,DBSRC)在传输功率的快速调控过程中,移相角将发生较大的阶跃变化,导致谐振腔出现大幅度长时间的振荡过程,不仅严重恶化了变换器的动态性能,电路元件也会面临严重的过电压和过电流风险。该文首先基于基波分析法推导DBSRC暂态过程的通用计算模型,分析暂态过程中的振荡特性,精确估算暂态过程中的谐振电压峰值、谐振电流峰值以及暂态过渡时间,评估暂态过程中的过电压与过电流程度。基于暂态过程计算模型,提出一种振荡的抑制方法,使变换器在一个开关周期后能够到达新的稳定状态,有效地避免了过电压与过电流的风险,并且大幅改善了闭环控制的动态特性。最后,通过仿真与实验结果验证理论分析和所提出的控制方法。展开更多
基金This work was supported by National Key Research and Development Program of China(No.2023YFB2405900)the Technology Project of China Southern PowerGrid(No.ZBKJXM20232198).
文摘Mid-and high-frequency resonance(MHFR)is highly likely to occur at the sending end of voltage source con-verter-based ultra-high voltage direct current(VSC-UHVDC)for large-scale renewable energy transmission.It is of great im-portance to investigate the resonance characteristics and the corresponding suppression strategies.Firstly,this paper intro-duces the overall'control scheme of VSC-UHVDC for large-scale renewable energy transmission.Then,the impedance mod-els of VSC under grid-forming control with AC voltage coordi-nated control are established.The mid-and high-frequency im-pedance characteristics of VSC-UHVDC are analyzed.The key factors affecting the impedance characteristics have been re-vealed,including the AC voltage control,the voltage feedfor-ward,the inner current loop,the positive-sequence and nega-tive-sequence independent control(PSNSIC),and the control de-lay.The MHFR characteristics at the sending-end system are analyzed in the whole operation process,including the black start and the normal power transmission operation.An integrat-ed control scheme is proposed to address the MHFR problems.Finally,extensive case studies are conducted on a planned VSC-UHVDC project to verify the theoretical analysis.
基金supported in part by the Jiangsu Natural Science Foundation of China under Grant BK20180013in part by the Shenzhen Science and Technology Innovation Committee(STIC)under Grant JCYJ20180306174439784.
文摘The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented.
文摘基于移相控制的双有源桥串联谐振变换器(dual-bridge series resonant converter,DBSRC)在传输功率的快速调控过程中,移相角将发生较大的阶跃变化,导致谐振腔出现大幅度长时间的振荡过程,不仅严重恶化了变换器的动态性能,电路元件也会面临严重的过电压和过电流风险。该文首先基于基波分析法推导DBSRC暂态过程的通用计算模型,分析暂态过程中的振荡特性,精确估算暂态过程中的谐振电压峰值、谐振电流峰值以及暂态过渡时间,评估暂态过程中的过电压与过电流程度。基于暂态过程计算模型,提出一种振荡的抑制方法,使变换器在一个开关周期后能够到达新的稳定状态,有效地避免了过电压与过电流的风险,并且大幅改善了闭环控制的动态特性。最后,通过仿真与实验结果验证理论分析和所提出的控制方法。
