Pub Date : 2024-12-12DOI: 10.1109/TPWRD.2024.3516951
Javier Vildósola;Asier Herranz;Amaia Arrinda;Igor Fernández;Itziar Angulo;Alexander Gallarreta;Jon González-Ramos;David de la Vega
The characterization of the grid access impedance, the Non-Intentional Emissions (NIEs) and the attenuation of the Low Voltage (LV) distribution grid is a major factor to be considered for the development of Power Line Communications (PLC) systems. Often, the measurement systems used for this characterization require the placement of extension cables to reach connection points, which greatly affect the results obtained in the MHz frequency range. This paper provides a new methodology for modelling and correcting the effects of the extension cables needed by measurement systems for online impedance measurements from 1.1 to 10 MHz. The proposed methodology has been applied to four different extension cables, assessing its accuracy, and it has been validated against online LV grid access impedance measurements. The results show that there is a great improvement in the error obtained with the proposed methodology over others previously presented.
{"title":"Methodology for Modeling and Correcting the Effects of Extension Cables for Measurements in Low Voltage Grids in the 1.1–10 MHz Frequency Band","authors":"Javier Vildósola;Asier Herranz;Amaia Arrinda;Igor Fernández;Itziar Angulo;Alexander Gallarreta;Jon González-Ramos;David de la Vega","doi":"10.1109/TPWRD.2024.3516951","DOIUrl":"10.1109/TPWRD.2024.3516951","url":null,"abstract":"The characterization of the grid access impedance, the Non-Intentional Emissions (NIEs) and the attenuation of the Low Voltage (LV) distribution grid is a major factor to be considered for the development of Power Line Communications (PLC) systems. Often, the measurement systems used for this characterization require the placement of extension cables to reach connection points, which greatly affect the results obtained in the MHz frequency range. This paper provides a new methodology for modelling and correcting the effects of the extension cables needed by measurement systems for online impedance measurements from 1.1 to 10 MHz. The proposed methodology has been applied to four different extension cables, assessing its accuracy, and it has been validated against online LV grid access impedance measurements. The results show that there is a great improvement in the error obtained with the proposed methodology over others previously presented.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"641-650"},"PeriodicalIF":3.8,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10797686","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-11DOI: 10.1109/TPWRD.2024.3516090
B. Kermani;R. Shariatinasab;M. Khorshidi;Jinliang He
Since photovoltaic systems (PVs) are installed in the open environment, they are exposed to lightning strokes in which the resulting overvoltages can lead to the failure of sensitive equipment including inverters and solar panels. This paper presents a method to analyze the lightning-related overvoltages in PVs and calculate the failure rate of sensitive equipment. In the presented method an accurate modeling of different equipment to perform the risk analysis of lightning transients is proposed. To evaluate the proposed method, a real PV power plant is simulated in EMTP software and the overvoltages caused by lightning stroke are calculated. The results of the simulation show that frequency-dependent modeling of PVs and modeling of the inverters’ heat sink has a significant effect on the estimation of overvoltages generated at different locations of the PV power plant. The paper also proposes a method to calculate the failure rate of different equipment of solar power plants, i.e., inverters and solar modules. By knowing the failure rate of the equipment, the reliability of the PVs can be evaluated more accurately and the implementation of a protection scheme for the lightning strokes can be achieved more economically.
{"title":"Risk Analysis of the Lightning-Related Transients on Photovoltaic Systems: Application to a Solar Power Plant Without a Lightning Protection System","authors":"B. Kermani;R. Shariatinasab;M. Khorshidi;Jinliang He","doi":"10.1109/TPWRD.2024.3516090","DOIUrl":"10.1109/TPWRD.2024.3516090","url":null,"abstract":"Since photovoltaic systems (PVs) are installed in the open environment, they are exposed to lightning strokes in which the resulting overvoltages can lead to the failure of sensitive equipment including inverters and solar panels. This paper presents a method to analyze the lightning-related overvoltages in PVs and calculate the failure rate of sensitive equipment. In the presented method an accurate modeling of different equipment to perform the risk analysis of lightning transients is proposed. To evaluate the proposed method, a real PV power plant is simulated in EMTP software and the overvoltages caused by lightning stroke are calculated. The results of the simulation show that frequency-dependent modeling of PVs and modeling of the inverters’ heat sink has a significant effect on the estimation of overvoltages generated at different locations of the PV power plant. The paper also proposes a method to calculate the failure rate of different equipment of solar power plants, i.e., inverters and solar modules. By knowing the failure rate of the equipment, the reliability of the PVs can be evaluated more accurately and the implementation of a protection scheme for the lightning strokes can be achieved more economically.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"618-629"},"PeriodicalIF":3.8,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142809748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-11DOI: 10.1109/TPWRD.2024.3515109
Chunke Hu;Xi Wu;Hui Cai
The embedded high voltage direct current (HVDC) transmission is a key strategy for augmenting power transmission capacity within limited corridors, particularly for large-scale renewable energy integration. Multi-type embedded HVDC combines advantages of different HVDC technologies, serving as an important method to improve the operation performance of the hybrid AC/DC power system. This paper investigates the impacts of multi-type embedded HVDC on the operation performance of the system, indicating the enhancement from multiple steady-state and transient perspectives. The coupling effects of power transmission and bus voltages are incorporated in the analysis, and three types of embedded HVDC systems are involved, including line-commutated converter (LCC), static synchronous compensator supported line-commutated converter (SLCC) and voltage source converter (VSC). The apparent increase in short circuit ratio (AISCR) indices are evaluated to measure the enhancement in terms of maximum available power (MAP), commutation failure immunity index (CFII) and temporary overvoltage (TOV) quantitatively. The fault recovery process is also studied with comprehensive analysis of the dynamic characteristics. The embedded SLCC-HVDC and VSC-HVDC systems provide reactive power compensation through tie lines, significantly enhancing MAP and fault recovery performance of the system. Static var generator (SVG) capacity cannot be fully exploited under the independent and constant control modes of SVG and VSC in analysis of CFII and TOV performance. A shorter electrical distance between receiving-end subsystems will be more beneficial to the enhancement and should be considered in the system planning.
{"title":"Research on the Operation Performance Enhancement of Hybrid AC/DC Power System With Multi-Type Embedded HVDC","authors":"Chunke Hu;Xi Wu;Hui Cai","doi":"10.1109/TPWRD.2024.3515109","DOIUrl":"10.1109/TPWRD.2024.3515109","url":null,"abstract":"The embedded high voltage direct current (HVDC) transmission is a key strategy for augmenting power transmission capacity within limited corridors, particularly for large-scale renewable energy integration. Multi-type embedded HVDC combines advantages of different HVDC technologies, serving as an important method to improve the operation performance of the hybrid AC/DC power system. This paper investigates the impacts of multi-type embedded HVDC on the operation performance of the system, indicating the enhancement from multiple steady-state and transient perspectives. The coupling effects of power transmission and bus voltages are incorporated in the analysis, and three types of embedded HVDC systems are involved, including line-commutated converter (LCC), static synchronous compensator supported line-commutated converter (SLCC) and voltage source converter (VSC). The apparent increase in short circuit ratio (AISCR) indices are evaluated to measure the enhancement in terms of maximum available power (MAP), commutation failure immunity index (CFII) and temporary overvoltage (TOV) quantitatively. The fault recovery process is also studied with comprehensive analysis of the dynamic characteristics. The embedded SLCC-HVDC and VSC-HVDC systems provide reactive power compensation through tie lines, significantly enhancing MAP and fault recovery performance of the system. Static var generator (SVG) capacity cannot be fully exploited under the independent and constant control modes of SVG and VSC in analysis of CFII and TOV performance. A shorter electrical distance between receiving-end subsystems will be more beneficial to the enhancement and should be considered in the system planning.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"606-617"},"PeriodicalIF":3.8,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-11DOI: 10.1109/TPWRD.2024.3516122
Chunqi Liu;Dongsheng Chen;Yimin Hou
High-impedance faults in three-core power cables gradually develop into serious faults. Hence, localizing high-impedance faults is the key to ensuring transmission line reliability. The fault location cannot be accurately located due to the low detection sensitivity of the time-domain reflection (TDR) method and interference peaks in the localization results of the frequency-domain reflection (FDR) method. A new spectrum of propagation function (SPF) based fault localization method is proposed in this paper. Cable's S-parameter model is first described to reveal the reason for the change in the resonant frequency in the SPF due to high-impedance faults. In addition, the integral transform algorithm is employed to extract the cable's fault location from the SPF; the method's feasibility is numerically verified. Finally, high-impedance faults are set up in a three-core cable of 100 m in length, and the SPF of the cable is measured via a vector network analyzer. Compared with the TDR and FDR methods, the proposed approach is more capable of identifying high-impedance faults and more dependable on localization results. The fault localization error is within 0.16%, which has good application value.
{"title":"Research on Early Three-Core Power Cable High-Impedance Fault Location Method Based on the Spectrum of Propagation Functions","authors":"Chunqi Liu;Dongsheng Chen;Yimin Hou","doi":"10.1109/TPWRD.2024.3516122","DOIUrl":"10.1109/TPWRD.2024.3516122","url":null,"abstract":"High-impedance faults in three-core power cables gradually develop into serious faults. Hence, localizing high-impedance faults is the key to ensuring transmission line reliability. The fault location cannot be accurately located due to the low detection sensitivity of the time-domain reflection (TDR) method and interference peaks in the localization results of the frequency-domain reflection (FDR) method. A new spectrum of propagation function (SPF) based fault localization method is proposed in this paper. Cable's S-parameter model is first described to reveal the reason for the change in the resonant frequency in the SPF due to high-impedance faults. In addition, the integral transform algorithm is employed to extract the cable's fault location from the SPF; the method's feasibility is numerically verified. Finally, high-impedance faults are set up in a three-core cable of 100 m in length, and the SPF of the cable is measured via a vector network analyzer. Compared with the TDR and FDR methods, the proposed approach is more capable of identifying high-impedance faults and more dependable on localization results. The fault localization error is within 0.16%, which has good application value.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"630-640"},"PeriodicalIF":3.8,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142809813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-11DOI: 10.1109/TPWRD.2024.3514705
SeyedFarhan HosseiniKordkheili;Mohsen Hamzeh
This paper proposes an AC Fault Ride-Through (AC-FRT) control for onshore Modular Multilevel Converter (MMC) stations in High Voltage Direct Current (HVDC) systems in accordance with modern grid codes. The presented strategy also provides a backup energy controller for AC faults for cross-control MMCs where the converter's total energy is normally regulated through the AC side current. The proposed AC-FRT control is capable of positive and negative sequence voltage support and properly limits current references to the specified safe limits accordingly with a tunable response time. Furthermore, the backup energy control allows for a distinct response for AC-FRT operation, independent of the energy controller employed during normal operation. The effectiveness of the proposed methods is validated using time-domain simulations in a Multi Terminal Direct Current (MTDC) grid. Furthermore, an analysis is carried out to determine the effects of the MMC energy controller and the AC-FRT controls on the AC and MTDC grids interlinked by the converter for different fault scenarios. The analyses above are used to attain a design process for the converter's AC-FRT control response time and backup energy controller in order to attain a reasonable balance between AC fault current response time and MTDC grid dynamic variations.
{"title":"Onshore AC Fault Ride-Through Control in Multi-Terminal HVDC Systems","authors":"SeyedFarhan HosseiniKordkheili;Mohsen Hamzeh","doi":"10.1109/TPWRD.2024.3514705","DOIUrl":"10.1109/TPWRD.2024.3514705","url":null,"abstract":"This paper proposes an AC Fault Ride-Through (AC-FRT) control for onshore Modular Multilevel Converter (MMC) stations in High Voltage Direct Current (HVDC) systems in accordance with modern grid codes. The presented strategy also provides a backup energy controller for AC faults for cross-control MMCs where the converter's total energy is normally regulated through the AC side current. The proposed AC-FRT control is capable of positive and negative sequence voltage support and properly limits current references to the specified safe limits accordingly with a tunable response time. Furthermore, the backup energy control allows for a distinct response for AC-FRT operation, independent of the energy controller employed during normal operation. The effectiveness of the proposed methods is validated using time-domain simulations in a Multi Terminal Direct Current (MTDC) grid. Furthermore, an analysis is carried out to determine the effects of the MMC energy controller and the AC-FRT controls on the AC and MTDC grids interlinked by the converter for different fault scenarios. The analyses above are used to attain a design process for the converter's AC-FRT control response time and backup energy controller in order to attain a reasonable balance between AC fault current response time and MTDC grid dynamic variations.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"596-605"},"PeriodicalIF":3.8,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-09DOI: 10.1109/TPWRD.2024.3514294
Xiaopeng Fu;Wei Wu;Peng Li;Jean Mahseredjian;Jianzhong Wu;Chengshan Wang
As the utilization of power electronic-based components in power systems continues to grow, a comprehensive understanding of their dynamics becomes increasingly important for system design, control and protection analysis. To meet practical needs, the high-fidelity but time-consuming electromagnetic transient (EMT) simulations are often required. To improve the performance of these simulations, a highly efficient splitting state-space method with numerical error control is proposed that reduces the computation workload. The method employs a generic decoupling principle to split the state-space equations of the converter-integrated power system and introduces the exponential splitting formulas of multiple orders accuracy to solve and then compose the splitting state-space equations. The decoupling principle is designed based on separation of time-varying portions of the state matrix, which is realized by locating the smallest subcircuit topology that is switch state-dependent, through automatic switch grouping and switch adjacent state variables (SASV) identification. A family of exponential splitting schemes is employed to accelerate the demanding matrix exponential calculation. The splitting state-space method undergoes comprehensive testing across various cases, including a distribution network with DC load, an LLC resonant converter, a large-scale wind farm, and an MMC circuit. The accuracy of the proposed method is thoroughly evaluated, and its efficiency is validated.
{"title":"Splitting State-Space Method for Converter-Integrated Power Systems EMT Simulations","authors":"Xiaopeng Fu;Wei Wu;Peng Li;Jean Mahseredjian;Jianzhong Wu;Chengshan Wang","doi":"10.1109/TPWRD.2024.3514294","DOIUrl":"10.1109/TPWRD.2024.3514294","url":null,"abstract":"As the utilization of power electronic-based components in power systems continues to grow, a comprehensive understanding of their dynamics becomes increasingly important for system design, control and protection analysis. To meet practical needs, the high-fidelity but time-consuming electromagnetic transient (EMT) simulations are often required. To improve the performance of these simulations, a highly efficient splitting state-space method with numerical error control is proposed that reduces the computation workload. The method employs a generic decoupling principle to split the state-space equations of the converter-integrated power system and introduces the exponential splitting formulas of multiple orders accuracy to solve and then compose the splitting state-space equations. The decoupling principle is designed based on separation of time-varying portions of the state matrix, which is realized by locating the smallest subcircuit topology that is switch state-dependent, through automatic switch grouping and switch adjacent state variables (SASV) identification. A family of exponential splitting schemes is employed to accelerate the demanding matrix exponential calculation. The splitting state-space method undergoes comprehensive testing across various cases, including a distribution network with DC load, an LLC resonant converter, a large-scale wind farm, and an MMC circuit. The accuracy of the proposed method is thoroughly evaluated, and its efficiency is validated.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"584-595"},"PeriodicalIF":3.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142796933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The diversity of line fault types, the uncertainty of fault resistances, the limitation of available fault information, and the similarity of positive pole currents under different work conditions challenge the fault diagnosis of DC microgrids. This paper proposes a double threshold fault diagnosis scheme for line faults with wide-range fault resistances only using local fault currents such as bus-side capacitor current and positive pole line current. One threshold is designed based on the bus-side capacitor current estimation through the bus-side capacitor voltage to detect low-resistance faults rapidly. The other threshold is designed based on a proposed weighted correlation coefficient between the bus-side capacitor current and positive pole line current to detect high-resistance faults under noise accurately. All types of line faults can be classified accurately in 1.5 ms based on the positive pole output current and the ratio of the bus-side capacitor current to the variation value of the positive pole output current. The proposed scheme improves the reliability and economy of fault diagnosis by only using positive pole information and non-real-time communication. Finally, the feasibility of the proposed fault diagnosis scheme is verified by simulations and experiments.
{"title":"A Novel Fault Diagnosis Scheme Based on Local Fault Currents for DC Microgrids","authors":"Weiwei Li;Hua Han;Yao Sun;Shimiao Chen;Hongyi Liu;Xinlong Zheng;Yonglu Liu;Jin Zhao","doi":"10.1109/TPWRD.2024.3510460","DOIUrl":"10.1109/TPWRD.2024.3510460","url":null,"abstract":"The diversity of line fault types, the uncertainty of fault resistances, the limitation of available fault information, and the similarity of positive pole currents under different work conditions challenge the fault diagnosis of DC microgrids. This paper proposes a double threshold fault diagnosis scheme for line faults with wide-range fault resistances only using local fault currents such as bus-side capacitor current and positive pole line current. One threshold is designed based on the bus-side capacitor current estimation through the bus-side capacitor voltage to detect low-resistance faults rapidly. The other threshold is designed based on a proposed weighted correlation coefficient between the bus-side capacitor current and positive pole line current to detect high-resistance faults under noise accurately. All types of line faults can be classified accurately in 1.5 ms based on the positive pole output current and the ratio of the bus-side capacitor current to the variation value of the positive pole output current. The proposed scheme improves the reliability and economy of fault diagnosis by only using positive pole information and non-real-time communication. Finally, the feasibility of the proposed fault diagnosis scheme is verified by simulations and experiments.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"570-583"},"PeriodicalIF":3.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142776326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-02DOI: 10.1109/TPWRD.2024.3509688
Bingxue Yang;Yujian Ding;Xiaoxu Ma;Zhanhui Lu;Xiuyuan Yao;Yu Su
With increasing altitude, the insulation strength of air gap decreases. Currently, research on gap discharge is primarily concentrated in low-altitude regions, lacking experimental and theoretical support for external insulation design of electrical equipment at high altitudes. To investigate the long-gap discharge characteristics at high altitudes, this study conducted experiments to obtain the switching impulse discharge characteristic curves of rod-plane gap at altitudes of 55 m, 2500 m, and 4300 m. In response to the distribution characteristics of the experimental data, we propose an invariant risk minimization neural network ensemble algorithm based on optimal transport. Based on experimental data, a breakdown voltage prediction model applicable to different altitudes was established. The model achieved an average error of 2.3% on the test set, validating its high accuracy and generalization. Additionally, the computational results of the proposed model were compared with existing altitude correction methods and other machine learning models, further validating its effectiveness. Finally, the model was utilized to obtain 50% breakdown voltage under typical meteorological conditions at different altitudes. The altitude correction method proposed in this paper can accommodate a wide range of climatic variations, thus providing valuable reference for the construction of high-altitude power grids.
{"title":"Altitude Correction of Switching Impulse Breakdown Voltage for Rod-Plane Long-Gap Based on OT-IRM Algorithm","authors":"Bingxue Yang;Yujian Ding;Xiaoxu Ma;Zhanhui Lu;Xiuyuan Yao;Yu Su","doi":"10.1109/TPWRD.2024.3509688","DOIUrl":"10.1109/TPWRD.2024.3509688","url":null,"abstract":"With increasing altitude, the insulation strength of air gap decreases. Currently, research on gap discharge is primarily concentrated in low-altitude regions, lacking experimental and theoretical support for external insulation design of electrical equipment at high altitudes. To investigate the long-gap discharge characteristics at high altitudes, this study conducted experiments to obtain the switching impulse discharge characteristic curves of rod-plane gap at altitudes of 55 m, 2500 m, and 4300 m. In response to the distribution characteristics of the experimental data, we propose an invariant risk minimization neural network ensemble algorithm based on optimal transport. Based on experimental data, a breakdown voltage prediction model applicable to different altitudes was established. The model achieved an average error of 2.3% on the test set, validating its high accuracy and generalization. Additionally, the computational results of the proposed model were compared with existing altitude correction methods and other machine learning models, further validating its effectiveness. Finally, the model was utilized to obtain 50% breakdown voltage under typical meteorological conditions at different altitudes. The altitude correction method proposed in this paper can accommodate a wide range of climatic variations, thus providing valuable reference for the construction of high-altitude power grids.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"548-557"},"PeriodicalIF":3.8,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142760396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-02DOI: 10.1109/TPWRD.2024.3510173
Debdeep Samajdar;Tanmoy Bhattacharya
A hybrid modular multilevel converter can tolerate dc short-circuit faults and also operate with lower dc-link voltage under polluted insulator conditions due to harsh atmospheric conditions in high-voltage direct current transmission applications. When the dc-link voltage falls significantly below its rated value, the ac modulation index becomes greater than unity, resulting in over-modulation conditions. During ‘moderate over-modulation’ conditions, the energy balancing between half-bridge (HB) and full-bridge (FB) sub-modules (SMs) is hampered due to the inequality in their voltage references. This paper proposes an arm voltage splitting technique to overcome this problem. However, if the dc-link voltage further drops and goes below a particular level, the arm current becomes unipolar. The HB SMs can either charge or discharge, which disrupts their energy balance. This condition is termed ‘severe over-modulation’ condition. To fix this problem, second-order harmonic circulating current (SHCC) injection along with voltage reference splitting technique is proposed. This gives an accurate quantitative value for the SHCC reference. To rectify the errors committed due to unmodeled dynamics, a simple closed-loop control technique is proposed to supplement the calculated value of SHCC reference. To illustrate the strategy's viability, different reduced dc-link operations including zero voltage ride-through are performed in a laboratory prototype.
{"title":"A Reliable Scheme for Full-Range of Reduced DC-Link Voltage Operation of Hybrid MMC With Zero Voltage Ride Through","authors":"Debdeep Samajdar;Tanmoy Bhattacharya","doi":"10.1109/TPWRD.2024.3510173","DOIUrl":"10.1109/TPWRD.2024.3510173","url":null,"abstract":"A hybrid modular multilevel converter can tolerate dc short-circuit faults and also operate with lower dc-link voltage under polluted insulator conditions due to harsh atmospheric conditions in high-voltage direct current transmission applications. When the dc-link voltage falls significantly below its rated value, the ac modulation index becomes greater than unity, resulting in over-modulation conditions. During ‘moderate over-modulation’ conditions, the energy balancing between half-bridge (HB) and full-bridge (FB) sub-modules (SMs) is hampered due to the inequality in their voltage references. This paper proposes an arm voltage splitting technique to overcome this problem. However, if the dc-link voltage further drops and goes below a particular level, the arm current becomes unipolar. The HB SMs can either charge or discharge, which disrupts their energy balance. This condition is termed ‘severe over-modulation’ condition. To fix this problem, second-order harmonic circulating current (SHCC) injection along with voltage reference splitting technique is proposed. This gives an accurate quantitative value for the SHCC reference. To rectify the errors committed due to unmodeled dynamics, a simple closed-loop control technique is proposed to supplement the calculated value of SHCC reference. To illustrate the strategy's viability, different reduced dc-link operations including zero voltage ride-through are performed in a laboratory prototype.","PeriodicalId":13498,"journal":{"name":"IEEE Transactions on Power Delivery","volume":"40 1","pages":"558-569"},"PeriodicalIF":3.8,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-28DOI: 10.1109/TPWRD.2024.3506940
C. Ozansoy;M. Faulkner
This research scrutinizes credibility of the third harmonic (I3h) current phasor relationship with respect to the fundamental voltage (V50-Hz) as a potential signature of Vegetation High Impedance Faults (VeHIFs) using data from continuous-contact ‘branch touching wire’ earth faults. Prior work argued on a distinct phasor relationship between I3h and V50-Hz. Common HIF models simulate this distinct phase relationship as ∼ 180° with near perfect stability after only few cycles. This work uses a dataset of 132 phase-to-earth (ph-to-e) VeHIF test recordings to analyse temporal variations in the I3h phase shift. The over-fault mean was ∼170° with a volatility (standard deviation (STD)) of 7°. Ninety-five percent of tests stabilised to these values within 1.25-s of fault inception. Outlier cases with long phase-shift stabilisation periods may pose a risk in the timely detection of earth faults. However, such cases were usually associated with low initial fault currents (If) for extended periods and were unlikely to cause ignition. Fault currents above 33mA are shown to have stable phase-shifts. Finally, a regressive statistical model is presented for modelling time sequences of I3h phase-shift with respect to V50-Hz.
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