Pub Date : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292850
Ying Xu, Zheng Zhao, B. Yue, Xuan Li
China is rich in offshore wind power resources. With the development of offshore wind power resources near the coast and the continuous improvement of technology, the development and utilization of offshore wind power resources away from the coast has become an inevitable trend. Voltage sourced converters high voltage direct current (VSC-HVDC) transmission is the best technical method to complete the collection and transmission of offshore wind power resources away from the coast. The transient overvoltage level of the VSC-HVDC system is an important factor in determining the insulation level of the equipment, air clearance and project costs. This paper adopts PSCAD/EMTDC simulation analysis method, and conducts research based on a real offshore wind power transmission project via VSC-HVDC under construction. This paper analyzes the characteristics of typical faults, as well as the transient overvoltage levels at key locations of both offshore converter station and onshore converter station under different operating conditions. The influences of different operating conditions on the overvoltage level are analyzed. Studies have shown that due to the capacitance effect of long-distance DC submarine cables, the fault characteristics and transient overvoltage duration of the DC system are far from the previous VSC-HVDC projects. Protection strategy, transmission power, switching strategy of DC energy dissipation device will all affect transient overvoltage. The feature of cable overvoltage is studied. The maximum transient overvoltage levels between terminals, phases and poles are obtained. The research conclusions can provide a theoretical basis for the development of equipment and the layout of converter stations. Furthermore, it also provides a reference for the follow-up offshore wind power transmission projects.
{"title":"Research on Transient Overvoltage Characteristics of VSC-HVDC Transmission System Connecting to Large-scale Offshore Wind Farm","authors":"Ying Xu, Zheng Zhao, B. Yue, Xuan Li","doi":"10.1109/HVDC50696.2020.9292850","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292850","url":null,"abstract":"China is rich in offshore wind power resources. With the development of offshore wind power resources near the coast and the continuous improvement of technology, the development and utilization of offshore wind power resources away from the coast has become an inevitable trend. Voltage sourced converters high voltage direct current (VSC-HVDC) transmission is the best technical method to complete the collection and transmission of offshore wind power resources away from the coast. The transient overvoltage level of the VSC-HVDC system is an important factor in determining the insulation level of the equipment, air clearance and project costs. This paper adopts PSCAD/EMTDC simulation analysis method, and conducts research based on a real offshore wind power transmission project via VSC-HVDC under construction. This paper analyzes the characteristics of typical faults, as well as the transient overvoltage levels at key locations of both offshore converter station and onshore converter station under different operating conditions. The influences of different operating conditions on the overvoltage level are analyzed. Studies have shown that due to the capacitance effect of long-distance DC submarine cables, the fault characteristics and transient overvoltage duration of the DC system are far from the previous VSC-HVDC projects. Protection strategy, transmission power, switching strategy of DC energy dissipation device will all affect transient overvoltage. The feature of cable overvoltage is studied. The maximum transient overvoltage levels between terminals, phases and poles are obtained. The research conclusions can provide a theoretical basis for the development of equipment and the layout of converter stations. Furthermore, it also provides a reference for the follow-up offshore wind power transmission projects.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133564510","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292887
Xiao Gu, Lu Chen, Yang Xu
Partial discharge testing under DC voltage can be used to detect possible insulation defect of extruded HVDC cable system. And electric field distribution and field change at the defect is a decisive factor of partial discharge. An XLPE bounded spherical air cavity model was established in this paper, and electrical field change during applied DC voltage decreasing and polarity reversal were studied. The influence of field coefficient of XLPE conductivity was considered during the simulation. The obtained results predicted partial discharge with polarity opposite to the initial applied DC voltage. And this deduction accords with reported experimental results.
{"title":"Electrical Field Change of an XLPE Bounded Air-filled Spherical Cavity during DC Voltage Decreasing and Voltage Polarity Reversal","authors":"Xiao Gu, Lu Chen, Yang Xu","doi":"10.1109/HVDC50696.2020.9292887","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292887","url":null,"abstract":"Partial discharge testing under DC voltage can be used to detect possible insulation defect of extruded HVDC cable system. And electric field distribution and field change at the defect is a decisive factor of partial discharge. An XLPE bounded spherical air cavity model was established in this paper, and electrical field change during applied DC voltage decreasing and polarity reversal were studied. The influence of field coefficient of XLPE conductivity was considered during the simulation. The obtained results predicted partial discharge with polarity opposite to the initial applied DC voltage. And this deduction accords with reported experimental results.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125633574","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292778
Yan Li, Hongzhi Liu, Y. Chi, Yiwen Fan, Xiangyu Li, F. Cheng, Zhibing Wang, Chunxia Wei, Lijun Xie
The adaptability of renewable energy connected to the VSC-HVDC grid will become an important issue affecting grid operation. In particular, the complex interaction between renewable power generation and the power grid brings new challenges to the renewable power generation and VSC-HVDC grid to achieve fault ride-through. Therefore, it is necessary to study the fault ride-through strategies of the VSC-HVDC grid-renewable power generation combined system. According to the operating characteristics and adaptability of renewable energy clusters connected to the VSC-HVDC grid under different faults, this paper proposes technical requirements for high- / low-voltage fault ride-through of renewable power plants that are connected to the grid in island operation, and analyzes key technologies for renewable power generation dealing with AC faults at the sending end of the grid in island integration mode. It is expected to realize joint fault ride-through of renewable energy and VSC-HVDC, thereby increasing the availability of the system, contributing to the safe and stable operation of renewable energy and VSC-HVDC grid, providing technical support for the planning of large-scale renewable energy delivery methods, and effectively guiding the planning and design of renewable energy and VSC-HVDC grid
{"title":"Fault Ride-through Demand of Large-scale Islanded Renewable Energy Connected to VSC-HVDC System and Its Key Technologies","authors":"Yan Li, Hongzhi Liu, Y. Chi, Yiwen Fan, Xiangyu Li, F. Cheng, Zhibing Wang, Chunxia Wei, Lijun Xie","doi":"10.1109/HVDC50696.2020.9292778","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292778","url":null,"abstract":"The adaptability of renewable energy connected to the VSC-HVDC grid will become an important issue affecting grid operation. In particular, the complex interaction between renewable power generation and the power grid brings new challenges to the renewable power generation and VSC-HVDC grid to achieve fault ride-through. Therefore, it is necessary to study the fault ride-through strategies of the VSC-HVDC grid-renewable power generation combined system. According to the operating characteristics and adaptability of renewable energy clusters connected to the VSC-HVDC grid under different faults, this paper proposes technical requirements for high- / low-voltage fault ride-through of renewable power plants that are connected to the grid in island operation, and analyzes key technologies for renewable power generation dealing with AC faults at the sending end of the grid in island integration mode. It is expected to realize joint fault ride-through of renewable energy and VSC-HVDC, thereby increasing the availability of the system, contributing to the safe and stable operation of renewable energy and VSC-HVDC grid, providing technical support for the planning of large-scale renewable energy delivery methods, and effectively guiding the planning and design of renewable energy and VSC-HVDC grid","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125256238","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292777
Song Yang, Xi Huifan, Liu Hongtao, Li Peng, Xue Guanghu
High Voltage Direct Current(HVDC) transmission projects has been playing crucial role in China Southern Power Grid. These projects transmit the numerous hydro electricity from Yunnan to Guangdong and Guangxi. Keeping these HVDC projects stabilized operating is important to the whole power grid. Different from Alternate Current(AC) transmission projects, 78% of debugging and checking work for HVDC devices is proceeding before being service as estimated. Currently about 65% electricity from western to eastern of China Southern Power Grid(CSG) is transmitted by HVDC devices. So generally speaking, the safety and reliability of half electricity from western to eastern of CSG is checking during this short period before being service. Until 2020,there are 10 HVDC channels transmitting hydro power to the eastern area in CSG. Meanwhile there are great progress in debugging and checking work for HVDC projects to keep the device and grid stable and reliable. Referring the resilience engineering, the STAMP and so other famous concepts about industrial safety, the paper illustrated the attribution method for safety, demonstrated that how to diminish the unknown risk and how to prove the efficiency is the core of resilience engineering. After that the paper divided the work of HVDC projects into 3 systems: devices system, power grid system and human factor system, summarized the principles for each system, and presented the concept of redefining the resilience engineering to the HVDC projects safety and stable. Based on the principles concluded, the paper presented the redefined resilience engineering as enough and comparable visibility, multiple controlling methods and prevention of unknown risk.
{"title":"Redefine Resilience Engineering:Based on Progress of Debugging and Checking Technology in HVDC Projects of CSG","authors":"Song Yang, Xi Huifan, Liu Hongtao, Li Peng, Xue Guanghu","doi":"10.1109/HVDC50696.2020.9292777","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292777","url":null,"abstract":"High Voltage Direct Current(HVDC) transmission projects has been playing crucial role in China Southern Power Grid. These projects transmit the numerous hydro electricity from Yunnan to Guangdong and Guangxi. Keeping these HVDC projects stabilized operating is important to the whole power grid. Different from Alternate Current(AC) transmission projects, 78% of debugging and checking work for HVDC devices is proceeding before being service as estimated. Currently about 65% electricity from western to eastern of China Southern Power Grid(CSG) is transmitted by HVDC devices. So generally speaking, the safety and reliability of half electricity from western to eastern of CSG is checking during this short period before being service. Until 2020,there are 10 HVDC channels transmitting hydro power to the eastern area in CSG. Meanwhile there are great progress in debugging and checking work for HVDC projects to keep the device and grid stable and reliable. Referring the resilience engineering, the STAMP and so other famous concepts about industrial safety, the paper illustrated the attribution method for safety, demonstrated that how to diminish the unknown risk and how to prove the efficiency is the core of resilience engineering. After that the paper divided the work of HVDC projects into 3 systems: devices system, power grid system and human factor system, summarized the principles for each system, and presented the concept of redefining the resilience engineering to the HVDC projects safety and stable. Based on the principles concluded, the paper presented the redefined resilience engineering as enough and comparable visibility, multiple controlling methods and prevention of unknown risk.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134307770","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292847
Chunke Hu, Chengyong Zhao, Jiangping Jing, Zhibing Wang
Wind farm integration by voltage source converter can mitigate negative influence by fluctuating output wind power. Besides, voltage source converter can provide the wind farm with necessary voltage support by controlling the AC voltage for normal operation of wind farm. Wind power integration by high voltage direct current transmission can be further researched, which includes islanded wind farm integration and bundled wind-thermal power integration. In a comparison among voltage source converters, hybrid modular multilevel converter is selected at sending end of the system and is connected with the wind farm. Line commutated converter is used at the receiving end with a comprehensive consideration of economy and technology. The wind farm integration by hybrid high voltage direct current system has obvious advantages when the receiving end is strong. Structure and operation principle of the system are introduced, and feasible control strategies of converters are devised. The hybrid system needs cooperation of voltage source converter and line commutated converter, especially during the startup procedure. A three-stage startup control strategy of the system is designed and verified by simulation. The startup process is smooth and stable, and after that, the system can track respective setting values accurately. Response of the system to fluctuating wind speed is studied. Output power of the wind farm changes with the wind speed, and power of the system will change accordingly. The system can operate normally under fluctuating wind speed.
{"title":"Control Strategies for Wind Farm Integration by Hybrid HVDC Transmission","authors":"Chunke Hu, Chengyong Zhao, Jiangping Jing, Zhibing Wang","doi":"10.1109/HVDC50696.2020.9292847","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292847","url":null,"abstract":"Wind farm integration by voltage source converter can mitigate negative influence by fluctuating output wind power. Besides, voltage source converter can provide the wind farm with necessary voltage support by controlling the AC voltage for normal operation of wind farm. Wind power integration by high voltage direct current transmission can be further researched, which includes islanded wind farm integration and bundled wind-thermal power integration. In a comparison among voltage source converters, hybrid modular multilevel converter is selected at sending end of the system and is connected with the wind farm. Line commutated converter is used at the receiving end with a comprehensive consideration of economy and technology. The wind farm integration by hybrid high voltage direct current system has obvious advantages when the receiving end is strong. Structure and operation principle of the system are introduced, and feasible control strategies of converters are devised. The hybrid system needs cooperation of voltage source converter and line commutated converter, especially during the startup procedure. A three-stage startup control strategy of the system is designed and verified by simulation. The startup process is smooth and stable, and after that, the system can track respective setting values accurately. Response of the system to fluctuating wind speed is studied. Output power of the wind farm changes with the wind speed, and power of the system will change accordingly. The system can operate normally under fluctuating wind speed.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133802715","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292714
Shiyi Sun, Lin Zhou, X. Xi
DC power grid has been considered as a better choice for large-scale new energy grid connection and long-distance transmission, which can effectively improve the stability and reliability of power grid. High voltage DC-DC converter, as one of the key devices connecting different voltage levels of DC system, plays the role of voltage matching, power flow control, fault isolation and so on. The paper proposed an improved single-phase DC-DC converter based on modular multilevel converter(MMC). It is a DC/AC/DC system with the intermediate medium frequency transformer. DC input voltage is inverted by VSC to intermediate frequency AC voltage, and then boosted by transformer. Finally, stable DC voltage is output by MMC rectification. The low voltage side adopts constant reactive power control, while the high voltage side adopts constant AC voltage control. With the midfrequency transformer, larger ratio can be got. In addition, properly increasing the AC frequency can reduce the volume and loss of the transformer and other passive components used in the circuit. The proposed topology structure and control strategy is validated by MATLAB SIMULINK simulation.
{"title":"An Improved DC-DC Converter Based on MMC","authors":"Shiyi Sun, Lin Zhou, X. Xi","doi":"10.1109/HVDC50696.2020.9292714","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292714","url":null,"abstract":"DC power grid has been considered as a better choice for large-scale new energy grid connection and long-distance transmission, which can effectively improve the stability and reliability of power grid. High voltage DC-DC converter, as one of the key devices connecting different voltage levels of DC system, plays the role of voltage matching, power flow control, fault isolation and so on. The paper proposed an improved single-phase DC-DC converter based on modular multilevel converter(MMC). It is a DC/AC/DC system with the intermediate medium frequency transformer. DC input voltage is inverted by VSC to intermediate frequency AC voltage, and then boosted by transformer. Finally, stable DC voltage is output by MMC rectification. The low voltage side adopts constant reactive power control, while the high voltage side adopts constant AC voltage control. With the midfrequency transformer, larger ratio can be got. In addition, properly increasing the AC frequency can reduce the volume and loss of the transformer and other passive components used in the circuit. The proposed topology structure and control strategy is validated by MATLAB SIMULINK simulation.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117309650","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292816
M. Feng, Chenxiang Gao, Jiangping Ding, Jianzhong Xu, Chengyong Zhao
This paper proposes a high-speed modeling architecture for fast electromagnetic transient (EMT) simulation of PETs. Unlike the existing modeling methods, the proposed technique recursively decreases the dimension order of the admittance matrix to obtain the generalized Norton equivalent of each phase leg. The final admittance matrix overlaid onto the external system admittance matrix has a dimension orders of magnitude remarkably smaller than that of the unreduced structure. By comparison with a detailed EMT model of a medium-voltage dc (MVDC) grid, the performance of the proposed scheme has been assessed in PSCAD/EMTDC under various working conditions. With negligible loss of accuracy, approximately one to two orders of magnitude speedup over a straightforward EMT program is achieved.
{"title":"High-Speed Modeling Architecture for Fast EMT Simulation of Power Electronic Transformers","authors":"M. Feng, Chenxiang Gao, Jiangping Ding, Jianzhong Xu, Chengyong Zhao","doi":"10.1109/HVDC50696.2020.9292816","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292816","url":null,"abstract":"This paper proposes a high-speed modeling architecture for fast electromagnetic transient (EMT) simulation of PETs. Unlike the existing modeling methods, the proposed technique recursively decreases the dimension order of the admittance matrix to obtain the generalized Norton equivalent of each phase leg. The final admittance matrix overlaid onto the external system admittance matrix has a dimension orders of magnitude remarkably smaller than that of the unreduced structure. By comparison with a detailed EMT model of a medium-voltage dc (MVDC) grid, the performance of the proposed scheme has been assessed in PSCAD/EMTDC under various working conditions. With negligible loss of accuracy, approximately one to two orders of magnitude speedup over a straightforward EMT program is achieved.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125409223","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292723
Jinlu Liu, Wenjie Chen, Xin Ma, Ru Zhang, Ruitao Yan
DC microgrids get a lot of attention because of its good characteristics. DC-DC converter is necessary in DC microgrids to interface energy. The dual active bridge (DAB) converter is one of most promising DC-DC converters. But when the normalized voltage gain is far from 1, the DAB converter is difficult to realize soft switching. In this paper, the neutral point clamped (NPC) dual-active-bridge (DAB) converter with a blocking capacitor is adopted. This converter is able to work in different modes to achieve wide zero voltage switching (ZVS) range. A ZVS range optimization strategy is proposed based on ZVS range analysis in different modes. This strategy makes the NPC DAB converter work in the optimal mode. The simulation results show this strategy is effective.
{"title":"A zero voltage switching range optimization strategy for NPC Dual-Active-Bridge Converter","authors":"Jinlu Liu, Wenjie Chen, Xin Ma, Ru Zhang, Ruitao Yan","doi":"10.1109/HVDC50696.2020.9292723","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292723","url":null,"abstract":"DC microgrids get a lot of attention because of its good characteristics. DC-DC converter is necessary in DC microgrids to interface energy. The dual active bridge (DAB) converter is one of most promising DC-DC converters. But when the normalized voltage gain is far from 1, the DAB converter is difficult to realize soft switching. In this paper, the neutral point clamped (NPC) dual-active-bridge (DAB) converter with a blocking capacitor is adopted. This converter is able to work in different modes to achieve wide zero voltage switching (ZVS) range. A ZVS range optimization strategy is proposed based on ZVS range analysis in different modes. This strategy makes the NPC DAB converter work in the optimal mode. The simulation results show this strategy is effective.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114709880","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292818
L. Wei, W. Hang, Chen Gen, Zhang Jian Wen, Cai Xu
The operating environment of offshore wind power is harsh, and the random fluctuation of wind power is large, which makes power devices easy to fail. Fault tolerant control is an effective means to improve the reliability and availability of wind power converters. Taking an open circuit fault of a parallel converter as an example, this paper analyzes the fault operation mechanism of a parallel wind power converter in detail. On this basis, a fault-tolerant control strategy based on negative-sequence current compensation is proposed, and a non-faulty converter module is used to compensate the negative-sequence current of the faulty converter module. When the system power is less than or equal to 0.5 pu, the maximum output power of the converter is realized under the condition of ensuring the current balance of the grid-connected side; when the system power is greater than 0.5pu, the negative sequence of the grid-side is controlled to minimum under the condition of outputting the maximum power. Finally, the correctness and feasibility of the control strategy theory are verified by simulation.
{"title":"Optimal Fault-tolerant Control for Improving the Availability of Parallel Wind Power Converters","authors":"L. Wei, W. Hang, Chen Gen, Zhang Jian Wen, Cai Xu","doi":"10.1109/HVDC50696.2020.9292818","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292818","url":null,"abstract":"The operating environment of offshore wind power is harsh, and the random fluctuation of wind power is large, which makes power devices easy to fail. Fault tolerant control is an effective means to improve the reliability and availability of wind power converters. Taking an open circuit fault of a parallel converter as an example, this paper analyzes the fault operation mechanism of a parallel wind power converter in detail. On this basis, a fault-tolerant control strategy based on negative-sequence current compensation is proposed, and a non-faulty converter module is used to compensate the negative-sequence current of the faulty converter module. When the system power is less than or equal to 0.5 pu, the maximum output power of the converter is realized under the condition of ensuring the current balance of the grid-connected side; when the system power is greater than 0.5pu, the negative sequence of the grid-side is controlled to minimum under the condition of outputting the maximum power. Finally, the correctness and feasibility of the control strategy theory are verified by simulation.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123862634","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 : 2020-11-06DOI: 10.1109/HVDC50696.2020.9292801
Zhigang Zhang, Mingrui Mo, Caizhu Wu
This paper proposes an improved and unified fixed-point iterative method to solve the power flow problem in three-phase distribution systems by phase-coordinates. The proposed method which has definitude physical meaning in essence is to searching for the equivalent admittance approximations of the loads. And an improved decoupled method in topology for modeling the distribution equipment is given, which makes the models of distribution equipment easy to integrate into the proposed method. The solution characteristics analysis of the proposed method is given as well. The validity and effectiveness of the proposed method can be demonstrated by the numerical test systems.
{"title":"Improved Phase-coordinate Fixed-point Iterative Method Based on Equivalent Admittance Approximation for Power Flow Calculation in Three-phase Distribution Systems","authors":"Zhigang Zhang, Mingrui Mo, Caizhu Wu","doi":"10.1109/HVDC50696.2020.9292801","DOIUrl":"https://doi.org/10.1109/HVDC50696.2020.9292801","url":null,"abstract":"This paper proposes an improved and unified fixed-point iterative method to solve the power flow problem in three-phase distribution systems by phase-coordinates. The proposed method which has definitude physical meaning in essence is to searching for the equivalent admittance approximations of the loads. And an improved decoupled method in topology for modeling the distribution equipment is given, which makes the models of distribution equipment easy to integrate into the proposed method. The solution characteristics analysis of the proposed method is given as well. The validity and effectiveness of the proposed method can be demonstrated by the numerical test systems.","PeriodicalId":298807,"journal":{"name":"2020 4th International Conference on HVDC (HVDC)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124021382","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}
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