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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

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

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)

Harmonic State Space Based Impedance Modeling and Virtual Impedance Based Stability Enhancement Control for LCC-HVDC Systems

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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

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改进型串联电压换相换流器及其控制策略

电网技术 2021年第10期45卷 4057-4065页

作者：陈斌超周小平罗安邓凌峰洪乐荣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

串联电压换相换流器(series voltage commutation converter,SVCC)是一种可以有效抑制高压直流输电换相失败的新型换流拓扑,但当交流系统故障程度超过SVCC抑制范围时,直流电流将急剧上升,对SVCC子模块中的绝缘栅双极型晶体管(insulated ... 详细信息

串联电压换相换流器(series voltage commutation converter,SVCC)是一种可以有效抑制高压直流输电换相失败的新型换流拓扑,但当交流系统故障程度超过SVCC抑制范围时,直流电流将急剧上升,对SVCC子模块中的绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)造成较大电流冲击,亟需研究应对措施减轻换相失败后IGBT所承受的电流应力。为此,提出了一种改进型串联电压换相换流器(improved-series voltage commutation converter,I-SVCC)拓扑,通过控制子模块6种工作状态的灵活切换,可实现对阀组的辅助换相;并在换相失败发生后,能够迅速将子模块电容从换相回路中切除,避免了子模块电容的故障过压问题,同时还降低了换相失败后故障电流对子模块中各IGBT的冲击,提升了其工程实用性。此外,还针对I-SVCC设计了系统换相失败后子模块的重新投入策略,使得I-SVCC具备了后续换相失败抑制能力。最后,在PSCAD/EMTDC环境下搭建了模型进行验证,结果证明了I-SVCC在降低IGBT峰值电流和抑制后续换相失败方面的有效性。

关键词：高压直流输电换相失败串联电压换相换流器绝缘栅双极型晶体管

含串补及STATCOM的交直流系统稳定性分析及改善方法

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电力系统自动化 2022年第22期46卷 151-162页

作者：夏海涛周小平刘一锋洪乐荣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

研究了受端交直流系统中由串补及静止同步补偿器(STATCOM)引发的小信号失稳问题。基于系统闭环传递函数的主导极点轨迹的变化规律,分析了串补电容、STATCOM及其并联数量对高压直流输电系统小信号稳定性的影响。理论结果表明:投入串补有... 详细信息

研究了受端交直流系统中由串补及静止同步补偿器(STATCOM)引发的小信号失稳问题。基于系统闭环传递函数的主导极点轨迹的变化规律,分析了串补电容、STATCOM及其并联数量对高压直流输电系统小信号稳定性的影响。理论结果表明:投入串补有利于系统低频和高频稳定性但会使系统增加一对中频极点,而该中频极点会降低系统整体的稳定裕度;投入STATCOM能增强系统中频阻尼,但随着其并联台数的增加,系统高频阻尼将会变弱。针对这一现象,从定关断角控制特性和频域阻抗(导纳)特性2个角度给出了相应的机理解释。为了改善系统中高频稳定性,提出了触发角指令反馈控制及有功电流补偿控制。然后,利用PSCAD/EMTDC仿真软件验证了上述理论分析结果的正确性及所提方法的有效性。最后,比较了逆变站分别采用定关断角控制和电压控制这2种情形下系统的稳定性差异。

关键词：高压直流输电电网换相换流器串补静止同步补偿器小信号稳定性控制灵敏度指标稳定性分析

虚拟惯性控制的负荷变换器接入弱电网的序阻抗建模与稳定性分析

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电工技术学报 2021年第4期36卷 843-856页

作者：刘一锋周小平洪乐荣夏海涛田皓国家电能变换与控制工程技术研究中心(湖南大学) 长沙410082 国网潜江市供电公司潜江433100

负荷虚拟同步机(LVSM)与基于直流侧电容虚拟惯性控制的负荷变换器(DLCVIC-LC)都能增强系统惯性,但也可能在弱电网下发生谐波振荡等交互稳定性问题。该文考虑直流电压控制以及频率耦合的影响,推导三相负荷变换器的序阻抗计算通式,并据此... 详细信息

负荷虚拟同步机(LVSM)与基于直流侧电容虚拟惯性控制的负荷变换器(DLCVIC-LC)都能增强系统惯性,但也可能在弱电网下发生谐波振荡等交互稳定性问题。该文考虑直流电压控制以及频率耦合的影响,推导三相负荷变换器的序阻抗计算通式,并据此建立LVSM以及DLCVIC-LC的精确序阻抗模型,进而对比分析两者的序阻抗特性。分析发现LVSM的正序阻抗基本呈感性,与电网的阻抗特性基本一致,不易发生谐波振荡问题;而DLCVIC-LC的正序阻抗在中频段呈负阻容性(相位在−90°~−180°),容易在弱电网中引发谐波振荡问题。此外,该文基于所建序阻抗模型和Nyquist稳定判据分析电网阻抗及控制参数对两种负荷变换器并网系统稳定性的影响。最后,通过实验验证了该文分析的正确性。

关键词：负荷变换器虚拟惯性序阻抗建模稳定性分析弱电网

基于电压时间换相面积预测的换相失败抑制方法

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电力系统自动化 2022年第3期46卷 156-163页

作者：朱仁龙周小平罗安洪乐荣夏海涛邓凌峰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

提前触发控制是降低高压直流输电系统换相失败发生概率的一种重要方法,精准的提前触发是该方法抑制换相失败的关键。根据换相电压时间面积理论,提出了一种基于换相电压时间面积预测的换相失败抑制方法。该方法不仅计及了故障后直流电流... 详细信息

提前触发控制是降低高压直流输电系统换相失败发生概率的一种重要方法,精准的提前触发是该方法抑制换相失败的关键。根据换相电压时间面积理论,提出了一种基于换相电压时间面积预测的换相失败抑制方法。该方法不仅计及了故障后直流电流的变化,还通过换相面积的测量间接计及了故障后换相角以及等效换相电抗的变化。同时,该方法具有较清晰的物理意义,不需要通过复杂的参数整定来提升换相失败抑制性能。最后,以PSCAD/EMTDC中CIGRE标准模型作为测试模型,在不同故障下验证了所提方法的有效性。

关键词：高压直流输电换相失败换相失败抑制换相角提前触发控制

抑制高压直流输电系统换相失败的可控串联电阻

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电网技术 2023年第6期47卷 2539-2548页

作者：夏海涛周小平陈斌超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) 湖南省长沙市410082

针对高压直流输电系统中的换相失败问题,提出一种基于可控串联电阻(controllableseriesresistor,CSR)的解决方案。该方案比已有的换相失败防御模块省去了工频变压器;如果提供的辅助电压幅值相同,则比桥式可控串联电容少二分之一的功率... 详细信息

针对高压直流输电系统中的换相失败问题,提出一种基于可控串联电阻(controllableseriesresistor,CSR)的解决方案。该方案比已有的换相失败防御模块省去了工频变压器;如果提供的辅助电压幅值相同,则比桥式可控串联电容少二分之一的功率器件。首先,给出了CSR的拓扑及控制。然后,基于准稳态方程分析了CSR的换相失败抑制机理及控制特性。结果表明,交流出线处的串联电阻能提高换相电压幅值并抑制相位超前跃变,从而有利于顺利换相。接着,损耗分析的结果显示,CSR稳态功率损耗仅占额定直流功率的0.045%,对系统正常功率传输的影响很小。最后,基于PSCAD/EMTDC电磁暂态模型的仿真结果验证了所提方案的有效性:CSR的换相失败抑制能力较标准系统提高6~7.2倍,比桥式可控电容提高80%~90%。

关键词：高压直流输电换相失败可控串联电阻