Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808421
A. Andreotti, Antonio Di Pasquale, F. Mottola, M. Pagano, D. Proto
Railway industry is experiencing a strong need of renewal and smart technology. Hence, advanced approaches are needed to improve efficiency and sustainability of railway operations. In urban contexts, the public railway sector is object of an inevitable process of revamping, which involves expectations of end-users, railway operators, local supply distributors or local authorities. This paper examines an urban railway power system, where a smart scenario is envisaged. Particularly, an Italian AC/DC railway power infrastructure is considered, and an energy efficiency strategy is assumed. Aim of the paper is to evaluate the voltage quality in the supplying distribution network for any operating conditions of the railway system. Also, the energy efficiency strategy is arranged to improve voltage quality. More specifically, the strategy exploits electrical energy storage systems recharged by regenerative braking of rolling stocks in order to increase efficiency of the whole system. Also, the storage system allows shaving the peak load demand aimed at improving the voltage quality. Numerical simulations are carried out, they provide power quality analysis by examining nodal voltages as a function of the efficiency measure. The behavior of the railway power system has been analyzed under different operating conditions.
{"title":"Voltage Quality of an AC Grid Supplying a Railway Power System with Energy Saving Strategy","authors":"A. Andreotti, Antonio Di Pasquale, F. Mottola, M. Pagano, D. Proto","doi":"10.1109/ICHQP53011.2022.9808421","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808421","url":null,"abstract":"Railway industry is experiencing a strong need of renewal and smart technology. Hence, advanced approaches are needed to improve efficiency and sustainability of railway operations. In urban contexts, the public railway sector is object of an inevitable process of revamping, which involves expectations of end-users, railway operators, local supply distributors or local authorities. This paper examines an urban railway power system, where a smart scenario is envisaged. Particularly, an Italian AC/DC railway power infrastructure is considered, and an energy efficiency strategy is assumed. Aim of the paper is to evaluate the voltage quality in the supplying distribution network for any operating conditions of the railway system. Also, the energy efficiency strategy is arranged to improve voltage quality. More specifically, the strategy exploits electrical energy storage systems recharged by regenerative braking of rolling stocks in order to increase efficiency of the whole system. Also, the storage system allows shaving the peak load demand aimed at improving the voltage quality. Numerical simulations are carried out, they provide power quality analysis by examining nodal voltages as a function of the efficiency measure. The behavior of the railway power system has been analyzed under different operating conditions.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132781193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808561
J. Sutaria, Á. Espín-Delgado, S. Rönnberg
The reliability of the electrical and cooling systems is of utmost importance for the uninterrupted operation of the data center information technology (IT) load. The electrical distribution of the data center includes many subsystems starting with the utility and building transformers, uninterruptible power supply (UPS), power distribution units (PDUs), and power supplies ultimately powering the fans and the internal components of IT equipment. The various converters in data centers emit switching frequency residue due to PWM (pulse width modulation) techniques. The switching frequency range falls within the supraharmonic range, i.e., 2 to 150 kHz. This paper aims to show, with measurements, the different types of supraharmonic emissions measured in the data center, and the difference between their maximum and average magnitudes. The paper shows a method to identify the equipment emitting supraharmonic emission and possible disturbances caused by it. The paper traces the propagation of supraharmonic emission from the source through the transformer to the grid. Lastly, a comparison of measurements is made with the compatibility levels given by standard IEC 61000-2-2.
{"title":"Supraharmonics within a Datacenter-Emission and Propagation","authors":"J. Sutaria, Á. Espín-Delgado, S. Rönnberg","doi":"10.1109/ICHQP53011.2022.9808561","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808561","url":null,"abstract":"The reliability of the electrical and cooling systems is of utmost importance for the uninterrupted operation of the data center information technology (IT) load. The electrical distribution of the data center includes many subsystems starting with the utility and building transformers, uninterruptible power supply (UPS), power distribution units (PDUs), and power supplies ultimately powering the fans and the internal components of IT equipment. The various converters in data centers emit switching frequency residue due to PWM (pulse width modulation) techniques. The switching frequency range falls within the supraharmonic range, i.e., 2 to 150 kHz. This paper aims to show, with measurements, the different types of supraharmonic emissions measured in the data center, and the difference between their maximum and average magnitudes. The paper shows a method to identify the equipment emitting supraharmonic emission and possible disturbances caused by it. The paper traces the propagation of supraharmonic emission from the source through the transformer to the grid. Lastly, a comparison of measurements is made with the compatibility levels given by standard IEC 61000-2-2.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133154674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808839
Miguel Romero-L, V. Quintero-Molina, Camilo Garzón, A. Pavas, A. Blanco, S. Kannan, Jan Meyer
The increasing penetration of distributed generation in microgrids and the connection of different types of electronic loads cause significant levels of supraharmonic emission, especially in islanded microgrids. In this paper loads with different circuit topologies are connected to a laboratory microgrid, and supraharmonic voltages and currents are analyzed in both interconnected and islanded mode. Different indexes were applied to evaluate the supraharmonic emissions in specific frequency bands. Additional combinations of loads are analyzed for the islanded microgrid with regard to different power contributions from the storage and the PV system are assessed to identify the impact of those elements on supraharmonic emission. Finally, measurements of supraharmonic impedance characteristics were performed to find possible causes of the supraharmonic levels, e.g. resonances.
{"title":"Analysis of supraharmonic emission in a microgrid in islanded and interconnected operation","authors":"Miguel Romero-L, V. Quintero-Molina, Camilo Garzón, A. Pavas, A. Blanco, S. Kannan, Jan Meyer","doi":"10.1109/ICHQP53011.2022.9808839","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808839","url":null,"abstract":"The increasing penetration of distributed generation in microgrids and the connection of different types of electronic loads cause significant levels of supraharmonic emission, especially in islanded microgrids. In this paper loads with different circuit topologies are connected to a laboratory microgrid, and supraharmonic voltages and currents are analyzed in both interconnected and islanded mode. Different indexes were applied to evaluate the supraharmonic emissions in specific frequency bands. Additional combinations of loads are analyzed for the islanded microgrid with regard to different power contributions from the storage and the PV system are assessed to identify the impact of those elements on supraharmonic emission. Finally, measurements of supraharmonic impedance characteristics were performed to find possible causes of the supraharmonic levels, e.g. resonances.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131989395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808456
R. Benato, G. Gardan, L. Rusalen
This paper aims at investigating the impact of the increasing demand for electricity on the power quality of the transmission networks. In particular, investigations on the transmission network structure as a source of voltage unbalance are made by performing numerical simulations. All the simulations are carried out by means of the MCA method, and by means of a novel three-phase power flow algorithm named as PFPD_3P. Moreover, proposals and discussions on possible power quality mitigation strategies on the transmission networks are presented (i.e., synchronous compensators installations and/or network reinforcements).
{"title":"Transmission Grid Power Quality: Unbalance Factor Forecast by a Novel Three-Phase Power Flow","authors":"R. Benato, G. Gardan, L. Rusalen","doi":"10.1109/ICHQP53011.2022.9808456","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808456","url":null,"abstract":"This paper aims at investigating the impact of the increasing demand for electricity on the power quality of the transmission networks. In particular, investigations on the transmission network structure as a source of voltage unbalance are made by performing numerical simulations. All the simulations are carried out by means of the MCA method, and by means of a novel three-phase power flow algorithm named as PFPD_3P. Moreover, proposals and discussions on possible power quality mitigation strategies on the transmission networks are presented (i.e., synchronous compensators installations and/or network reinforcements).","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131990881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808644
S. Elphick, D. Robinson, J. Knott, S. Perera, Izzah Afandi, N. Wilmot
An unexpected challenge facing network operators due to high penetration levels of small-scale solar photovoltaic occurs when diesel backup generators are used to maintain supply to small network islands during maintenance. Most grid-connected small-scale solar inverters in Australia have no means of grid control and it is uneconomical to individually isolate each device within premises. Taking advantage of out of frequency protection settings of the inverters to disable output of distributed generation is one potential mechanism Network Service Providers are considering when operating the diesel generator. This is achieved by operating the diesel generation at a frequency above or below the inverter out of frequency settings. This paper investigates the potential impact of this operation on other connected loads, specifically 44 domestic appliances. The impact on electrical parameters RMS current, real and reactive power, displacement power factor, and current total harmonic distortion, as well as relevant actuation and operation are monitored for operating frequencies selected by the Network Service Providers to ensure solar inverters will either disconnect from or will not connect to the network, and for frequency variations expected on the modern network. The resulting parameters for each appliance are reported with only minor maloperation found for one of the appliances during testing.
{"title":"Quantifying the impact of supply frequency adjustments for DER control on consumer appliances","authors":"S. Elphick, D. Robinson, J. Knott, S. Perera, Izzah Afandi, N. Wilmot","doi":"10.1109/ICHQP53011.2022.9808644","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808644","url":null,"abstract":"An unexpected challenge facing network operators due to high penetration levels of small-scale solar photovoltaic occurs when diesel backup generators are used to maintain supply to small network islands during maintenance. Most grid-connected small-scale solar inverters in Australia have no means of grid control and it is uneconomical to individually isolate each device within premises. Taking advantage of out of frequency protection settings of the inverters to disable output of distributed generation is one potential mechanism Network Service Providers are considering when operating the diesel generator. This is achieved by operating the diesel generation at a frequency above or below the inverter out of frequency settings. This paper investigates the potential impact of this operation on other connected loads, specifically 44 domestic appliances. The impact on electrical parameters RMS current, real and reactive power, displacement power factor, and current total harmonic distortion, as well as relevant actuation and operation are monitored for operating frequencies selected by the Network Service Providers to ensure solar inverters will either disconnect from or will not connect to the network, and for frequency variations expected on the modern network. The resulting parameters for each appliance are reported with only minor maloperation found for one of the appliances during testing.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134084971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808569
Júlio César Cândido Vieira, Damásio Fernandes Júnior, W. A. Neves, F. Lopes
An evaluation of classical one- and two-terminal fault location methods based on traveling waves theory is presented in this paper. This evaluation is carried out considering the Madeira River HVDC system modeled in ATP/ATPDraw software, which is composed by a transmission line modeled considering the frequency dependence of the line parameters. In order to evaluate the efficiency of the methods, different fault scenarios are evaluated, being generated by varying the fault type, resistance and distance, totaling 1764 different cases. From the obtained results, the influence of distance and resistance of fault on the methods efficiency is evaluated. Moreover, the main sources of localization errors for each method are presented, highlighting the practical aspects and the main challenges in applying the methods in real systems.
{"title":"Challenges in Application of the Traveling Wave-Based Fault Location Methods Applied to HVDC Systems: Evaluation of Classical One- and Two-Terminal Methods","authors":"Júlio César Cândido Vieira, Damásio Fernandes Júnior, W. A. Neves, F. Lopes","doi":"10.1109/ICHQP53011.2022.9808569","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808569","url":null,"abstract":"An evaluation of classical one- and two-terminal fault location methods based on traveling waves theory is presented in this paper. This evaluation is carried out considering the Madeira River HVDC system modeled in ATP/ATPDraw software, which is composed by a transmission line modeled considering the frequency dependence of the line parameters. In order to evaluate the efficiency of the methods, different fault scenarios are evaluated, being generated by varying the fault type, resistance and distance, totaling 1764 different cases. From the obtained results, the influence of distance and resistance of fault on the methods efficiency is evaluated. Moreover, the main sources of localization errors for each method are presented, highlighting the practical aspects and the main challenges in applying the methods in real systems.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125196086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808751
P. Shcherbakova, A. Abramovitz, Gennady Senderovych
This paper reevaluates the active power direction method for locating the distortion sources in the power distribution network. The inaccuracies in the earlier analysis challenging the active power direction method are identified and the earlier claim of the inconsistency of the method is reconsidered.
{"title":"Reexamination of the Active Power Direction Method for Identifying the Sources of Harmonic Distortion","authors":"P. Shcherbakova, A. Abramovitz, Gennady Senderovych","doi":"10.1109/ICHQP53011.2022.9808751","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808751","url":null,"abstract":"This paper reevaluates the active power direction method for locating the distortion sources in the power distribution network. The inaccuracies in the earlier analysis challenging the active power direction method are identified and the earlier claim of the inconsistency of the method is reconsidered.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117319102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808700
D. Sabin, Colton Peltier
This paper summarizes a software algorithm used to automatically classify voltage sags using an expert systems and machine learning algorithms. In particular, the paper focuses on algorithms used to classify voltage sag events that were caused by downstream events (faults, inrush, or load start events) and voltage sags cause by upstream events.
{"title":"Utilization of an Expert System Enhanced with Machine Learning for Automatic Voltage Sag Identification and Analysis","authors":"D. Sabin, Colton Peltier","doi":"10.1109/ICHQP53011.2022.9808700","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808700","url":null,"abstract":"This paper summarizes a software algorithm used to automatically classify voltage sags using an expert systems and machine learning algorithms. In particular, the paper focuses on algorithms used to classify voltage sag events that were caused by downstream events (faults, inrush, or load start events) and voltage sags cause by upstream events.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116623640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808623
F. G. Montoya, F. Arrabal-Campos, A. Alcayde, Xabier Prado-Orbán, Jorge Mira
This document aims to establish an alternative physical formulation for the harmonic power flow in electrical systems provided by Geometric Algebra (GA) and the Poynting Vector (PV) and Poynting Theorem (PT). Given the traditional definition of PV (Abraham approach) as the vector product of the electric field and magnetic field, we exploit the property of the vector product as a dual form of the much more powerful wedge product operator from exterior algebra. Using concepts of vector spaces, we develop a completely GA-based approach founded on top of the isomorphism among periodic time-domain signals and Euclidean spaces. Our investigations shed more light on the long-running discussion of electric power flow in non-sinusoidal and non-linear electrical power systems.
{"title":"Geometric Power and Poynting Vector: a Physical Derivation for Harmonic Power Flow using Geometric Algebra","authors":"F. G. Montoya, F. Arrabal-Campos, A. Alcayde, Xabier Prado-Orbán, Jorge Mira","doi":"10.1109/ICHQP53011.2022.9808623","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808623","url":null,"abstract":"This document aims to establish an alternative physical formulation for the harmonic power flow in electrical systems provided by Geometric Algebra (GA) and the Poynting Vector (PV) and Poynting Theorem (PT). Given the traditional definition of PV (Abraham approach) as the vector product of the electric field and magnetic field, we exploit the property of the vector product as a dual form of the much more powerful wedge product operator from exterior algebra. Using concepts of vector spaces, we develop a completely GA-based approach founded on top of the isomorphism among periodic time-domain signals and Euclidean spaces. Our investigations shed more light on the long-running discussion of electric power flow in non-sinusoidal and non-linear electrical power systems.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116993359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-29DOI: 10.1109/ICHQP53011.2022.9808615
N. Nakhodchi, M. Bollen
This paper presents the impact of load impedance uncertainty on harmonic source and transfer impedance and consequently on harmonic propagation in distribution networks. A generic MV/LV model of the network and a more detailed model of an existing network are used. Both models include MV network and remote LV customers. Utilizing a Monte Carlo simulation method, it is shown that variation in load impedance has a big impact on the main resonant frequency of the local network but only limited influence on resonant frequency caused by remote loads connected to other LV networks.
{"title":"Including Load Impedance Uncertainty in Harmonic Impedance Seen from a Low-voltage Customer","authors":"N. Nakhodchi, M. Bollen","doi":"10.1109/ICHQP53011.2022.9808615","DOIUrl":"https://doi.org/10.1109/ICHQP53011.2022.9808615","url":null,"abstract":"This paper presents the impact of load impedance uncertainty on harmonic source and transfer impedance and consequently on harmonic propagation in distribution networks. A generic MV/LV model of the network and a more detailed model of an existing network are used. Both models include MV network and remote LV customers. Utilizing a Monte Carlo simulation method, it is shown that variation in load impedance has a big impact on the main resonant frequency of the local network but only limited influence on resonant frequency caused by remote loads connected to other LV networks.","PeriodicalId":249133,"journal":{"name":"2022 20th International Conference on Harmonics & Quality of Power (ICHQP)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125353619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：