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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 287-298页

作者： Yifeng Liu Xiaoping Zhou Quan Chen hanhang yin Lerong Hong Hao Tian ying Chen Siyuan Li the College of Electrical and Information Engineering Hunan UniversityChangsha 410082China the Zhejiang Magtron Intelligent Technology Limited Cooperation Jiaxing 314000China the State Grid Qianjiang Electric Power Company Qianjiang 433100China

Line commutated converter based high-voltage direct-current(LCC-HVDC)transmissions are prone to harmonic oscillation under weak *** modeling is an effective method for assessing interaction ***,this paper proposes an improved calculation method for the DC voltage and AC currents of commutation stations to address the complex linearization of the commutation process and constructs an overall harmonic state-space(HSS)model of an *** on the HSS model,the closed-loop AC impedances on the LCC-HVDC sending and receiving ends are then derived and *** impedance characteristics of the LCC-HVDC are then analyzed to provide a physical explanation for the harmonic oscillation of the *** effects of the grid strength and control parameters on system stability are also *** improve the impedance characteristics and operating stability of the LCC-HVDC system,a virtual impedance based stability enhancement control is proposed,and a parameter design method is considered to ensure satisfactory phase margins at both the sending and receiving ***,simulation results are presented to verify the validity of the impedance model and virtual impedance based stability enhancement control.

关键词： Line commutated converter based high-voltage direct-current(LCC-HVDC)transmission harmonic state space stability analysis harmonic oscillation virtual impedance

计及电网侧储能交互作用的MIDC后续换相失败机理分析及抑制策略

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高电压技术 2024年第7期50卷 2820-2832页

作者：尹寒航周小平陈燕东邓凌峰洪乐荣朱仁龙国家电能变换与控制工程技术研究中心(湖南大学) 长沙410082

利用电网侧储能的无功支撑能力有望改善多馈入直流输电(multi-infeed high voltage direct current,MIDC)的电压暂态特性,但是电网侧储能接入后,电力电子装备之间的相互作用会影响MIDC控制特性。在计及电网侧储能与MIDC交互作用基础上,... 详细信息

利用电网侧储能的无功支撑能力有望改善多馈入直流输电(multi-infeed high voltage direct current,MIDC)的电压暂态特性,但是电网侧储能接入后,电力电子装备之间的相互作用会影响MIDC控制特性。在计及电网侧储能与MIDC交互作用基础上,分析了故障持续阶段与故障清除阶段的MIDC后续换相失败机理。研究表明,在故障持续阶段,由于电网侧储能的交互作用,定电流控制切换为定关断角控制时直流电流更大,并且电流偏差控制输出减少使越前触发角下降,造成换相供给面积不足的影响更大;在故障清除阶段,计及直流电流振荡影响,越前触发角下降及大幅波动会导致换相供给面积不足;在MIDC系统处于功率恢复过程中,若电网侧储能无功功率指令置为0,将增大后续换相失败风险。然后,针对电网侧储能以及MIDC控制策略进行改进,提出了计及电网侧储能交互作用的MIDC后续换相失败抑制策略。最后,在多种故障类型下仿真验证了所提控制策略有效性。

关键词：多馈入直流输电系统电网侧储能后续换相失败机理分析抑制策略

A Commutation Failure Prediction and Mitigation Method

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Journal of Modern Power Systems and Clean Energy 2022年第3期10卷 779-787页

作者： Renlong Zhu Xiaoping Zhou Haitao Xia Lerong Hong hanhang yin College of Electrical and Information Engineering Hunan UniversityChangsha 410082China

The mitigation of commutation failure(CF)depends on the accuracy of CF *** terms of the large error of the existing extinction angle(EA)calculation during the fault transient period,a method for CF prediction and mitigation is *** in both DC current and overlap angle(OA)are considered in the proposed method to predict the EA *** addition,variations in critical EA and the effect of firing angle(FA)on both DC current and OA are considered in the proposed method to obtain the accurate FA order for the control *** proposed method can achieve good performance in terms of CF mitigation and reduce reactive consumption at the inverter side when a fault *** results based on the PSCAD/EMTDC show that the proposed method predicts CF rapidly and exhibits good performance in terms of CF mitigation.

关键词： Commutation failure prediction commutation failure mitigation line commutated converter based high-voltage direct current(LCC-HVDC) extinction angle(EA) overlap angle(OA) firing angle(FA)

DC Current Order Optimization Based Strategy for Recovery Performance Improvement of LCC-HVDC Transmission Systems

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Journal of Modern Power Systems and Clean Energy 2023年第3期11卷 1020-1026页

作者： Renlong Zhu Xiaoping Zhou Shuchen Luo Lerong Hong hanhang yin Yifeng Liu College of Electrical and Information Engineering Hunan UniversityChangsha 410082China State Grid Hunan Electric Power Company Limited Economical and Technical Research Institute Changsha 410011China

For the safe and fast recovery of line commutated converter based high-voltage direct current(LCC-HVDC)transmission systems after faults,a DC current order optimization based strategy is *** the constraint of electric and control quantities,the DC current order with the maximum active power transfer is calculated by Thevenin equivalent parameters(TEPs)and quasi-state equations of LCC-HVDC transmission ***,to mitigate the subsequent commutation failures(SCFs)that may come with the fault recovery process,the maximum DC current order that avoids SCFs is calculated through imaginary commutation ***,the minimum value of the two DC current orders is sent to the control *** results based on PSCAD/EMTDC show that the proposed strategy mitigates SCFs effectively and exhibits good performance in recovery.

关键词： Line commutated converter(LCC) high-voltage direct current(HVDC) DC current order calculation subsequent commutation failure(SCF) recovery

Calculation Method for Commutation Failure Fault Level in LCC-HVDC System Under Single-line-to-ground Faults Considering DC Current Variation

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1995-2002页

作者： Renlong Zhu Xiaoping Zhou hanhang yin Lerong Hong An Luo Yandong Chen Hanting Peng College of Electrical and Information Engineering Hunan UniversityChangsha 410082China School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China

Earlier studies have reported some calculation methods for commutation failure fault level(CFFL) in line-commutated-converter based high-voltage direct current(LCCHVDC) system under single-line-to-ground(SLG) faults. The accuracy of earlier methods is limited because they only consider the commutating voltage drop and phase shift, while neglecting the DC current variation. Hence, this paper proposes a CFFL calculation method under SLG faults considering DC current variation, for better planning and designing of LCC-HVDC systems. First, the fault commutating voltage magnitude and phase shift are calculated. Then, the fault DC voltage during different commutation processes is deduced. Based on the commutating voltage magnitude and phase shift, and DC voltage during different commutation processes under SLG faults, the characteristics of CFFL with different fault time are demonstrated and analyzed. Next, the transient time-domain response of the DC current after the fault is obtained based on the DC transmission line model. Discrete commutation processes are constructed based on the commutation voltage-time area rule to solve the extinction angle under different fault levels and fault time. Finally, the CFFL is calculated considering the fault time, commutating voltage drop, phase shift, and DC current variation. The accuracy of the proposed method compared with the traditional method is validated based on the CIGRE benchmark model in PSCAD/EMTDC.

关键词： Commutation failure(CF) commutation failure fault level(CFFL) line-commutated-converter-based highvoltage direct current(LCC-HVDC) single-line-to-ground(SLG)fault

Commutation Failure Mitigation Method Based on Imaginary Commutation Process

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Journal of Modern Power Systems and Clean Energy 2022年第5期10卷 1413-1422页

作者： Renlong Zhu Xiaoping Zhou Haitao Xia Lerong Hong hanhang yin Lingfeng Deng Yifeng Liu College of Electrical and Information Engineering Hunan UniversityChangsha 410082China

The commutation failure(CF) mitigation effectiveness is normally restricted by the delay of extinction angle(EA)measurement or the errors of existing prediction methods for EA or firing angle(FA). For this purpose, this paper proposes a CF mitigation method based on the imaginary commutation process. For each sample point, an imaginary commutation process is constructed to simulate the actual commutation ***, the imaginary EA is calculated by comparing the imaginary supply voltage-time area and the imaginary demand voltage-time area, which can update the imaginary EA earlier than the measured EA. In addition, the proposed method considers the impacts of commutation voltage variation, DC current variation, and phase angle shift of commutation voltage on the commutation process, which can ensure a more accurate EA calculation. Moreover, the DC current prediction is proposed to improve the CF mitigation performance under the single-phase AC faults. Finally, the simulation results based on CIGRE model prove that the proposed method has a good performance in CF mitigation.

关键词： Commutation failure(CF) commutation failure mitigation extinction angle line commutated converter based high-voltage direct current(LCC-HVDC)

弱受端场景下角型链式STATCOM接入HVDC系统的阻抗建模及稳定性分析

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电网技术 2023年第3期47卷 1269-1279页

作者：刘一锋周小平洪乐荣夏海涛尹寒航朱仁龙邓凌峰陈斌超国家电能变换与控制工程技术研究中心(湖南大学) 湖南省长沙市410082

为抑制电网换相换流器型高压直流输电(line-commutated converter based high-voltage direct-current,LCC-HVDC)换相失败的发生,静止同步补偿器(static synchronous compensator,STATCOM)在受端系统得到应用。然而随着LCC-HVDC系统的发展及新型电力系统的构建,受端电网呈现弱电网的特征。在弱电网条件下,LCC-HVDC系统、STATCOM与弱受端电网交互作用容易引发谐波振荡。该文采用阻抗分析法分析了含角型链式STATCOM的LCC-HVDC系统与受端电网的交互稳定性问题。首先提出一种改进的LCC交流电流和直流电压计算方式,以避免LCC复杂的换相开关函数的线性化。然后基于谐波状态空间(harmonic state space,HSS)理论,分别推导了LCC-HVDC系统以及角型链式STATCOM的多输入多输出(multi-input multi-output,MIMO)阻抗模型。此外,为了便于阻抗测量和稳定性分析,将MIMO阻抗模型等效转化为单输入单输出(single-input single-output,SISO)阻抗模型,并分析了角型链式STATCOM未接入和接入LCC-HVDC系统下的阻抗特性,揭示了含角型链式STATCOM的LCC-HVDC系统在弱受端电网下振荡的机理。分析表明:LCC-HVDC系统单独运行时受端系统容易在中低频段出现正序谐波振荡,而角型链式STATCOM接入后受端系统容易在中低频段内出现负序谐波振荡。最后,通过仿真验证了分析的正确性。

关键词：电网换相换流器型高压直流输电角型链式静止同步补偿器谐波状态空间建模阻抗模型稳定性分析

考虑光伏发电单元孤岛检测影响的直流电网稳定性分析与阻尼控制

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中国电机工程学报 2021年第1期41卷 109-122页

作者：黄旭程何志兴刘亚丽伍文华尹寒航陈燕东罗安国家电能变换与控制工程技术研究中心(湖南大学) 湖南省长沙市410082 全球能源互联网研究院有限公司北京市昌平区102209

直流电网适合大规模光伏发电的集成接入。光伏发电单元在接入直流电网运行时,需要依托孤岛检测方法,使得发电单元可以在异常断开状态下得到保护。然而,前馈孤岛检测方法会向直流电网注入扰动,影响光伏发电单元在并网运行时的性能,甚至... 详细信息

直流电网适合大规模光伏发电的集成接入。光伏发电单元在接入直流电网运行时,需要依托孤岛检测方法,使得发电单元可以在异常断开状态下得到保护。然而,前馈孤岛检测方法会向直流电网注入扰动,影响光伏发电单元在并网运行时的性能,甚至加剧由于变换器交互作用造成的振荡失稳问题。对此,建立直流电网中光伏发电单元、交直流互联变换器的小信号阻抗模型,并综合考虑最大功率跟踪控制、前馈孤岛检测方法对光伏Buck变换器端口特性的影响,探究影响直流电网稳定性的因素。然后,在不影响孤岛检测的情况下,提出一种有源阻尼稳定控制方法,在并网运行的光伏发电单元的直流电网侧端口串入虚拟电阻,使发电单元在输出不同功率时均有较好的稳定性。最后,仿真研究验证了分析内容的准确性和所提阻尼方法的有效性。

关键词：光伏发电单元孤岛检测直流电网稳定性分析阻尼控制

适用于串联电压换相换流器的新型换相失败抑制方法

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中国电机工程学报 2021年第21期41卷 7304-7313页

作者：邓凌峰周小平洪乐荣陈斌超夏海涛尹寒航刘一锋朱仁龙国家电能变换与控制工程技术研究中心(湖南大学) 湖南省长沙市410000

为了进一步提升串联电压换相换流器(series voltage commutated converter,SVCC)的换相失败抑制能力和运行稳定性,该文提出一种适用于SVCC的新型换相失败抑制方法,根据交流电压跌落程度灵活控制接入系统的变流链电容电压值,通过配合阀... 详细信息

为了进一步提升串联电压换相换流器(series voltage commutated converter,SVCC)的换相失败抑制能力和运行稳定性,该文提出一种适用于SVCC的新型换相失败抑制方法,根据交流电压跌落程度灵活控制接入系统的变流链电容电压值,通过配合阀组换相过程来构造变流链子模块的提前触发脉冲信号,解决SVCC变流链子模块运行时电容电压不平衡的问题,提升直流输电系统换相失败抵御能力。此外,还提出适用于SVCC系统的故障检测方法,利用最小方差(least error squares,LES)滤波器快速提取电网基波电压信息,检测受端电网故障,并获得表征受端电网故障程度的变流链电容电压控制指令。同时从理论上分析SVCC变流链可在电容电压调整过程中为系统提供更多的无功功率,降低换流器对交流电网的无功需求。最后,在PSCAD/EMTDC环境下搭建模型进行验证,结果表明SVCC新型控制方法可以提升直流输电系统的换相失败抵御能力,并在受端电网故障下降低阀组对电网的无功需求。

关键词：串联电压换相变流器新型控制方法可控电容电压换相失败

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球晶材料的TEM—EDAX剖析

无机材料学报 1997年第5期12卷 659-664页

作者：张干城王开泰李汉良沈定坤中国科学院上海硅酸盐研究所上海200050

观察了R2O－RO－Al2O3-SiO2系某一整体析出球晶的微晶玻璃中球晶的生长过程．获得随着晶化时间的增加或晶化温度升高，球晶直径增大；但球晶数目保持不变．发现了核化温度与球晶直径关系呈抛物线型．以TEM－EDAX剖析了球晶的雏型内部和... 详细信息

观察了R2O－RO－Al2O3-SiO2系某一整体析出球晶的微晶玻璃中球晶的生长过程．获得随着晶化时间的增加或晶化温度升高，球晶直径增大；但球晶数目保持不变．发现了核化温度与球晶直径关系呈抛物线型．以TEM－EDAX剖析了球晶的雏型内部和近邻玻璃基体的显微结构及其演变．清楚地揭示了球晶生长过程中所发生的组成变化．

关键词：球晶微晶玻璃显微结构玻璃晶化 TEM-EDAX法