The rapid advancement of modular multi-level converter-based high-voltage direct current(MMC-HVDC)interconnection projects may lead to torsional vibrations in turbo-generator shafts,causing oscillations that pose oper...The rapid advancement of modular multi-level converter-based high-voltage direct current(MMC-HVDC)interconnection projects may lead to torsional vibrations in turbo-generator shafts,causing oscillations that pose operational risks to the power system.Impedance-based analysis is an effective method to eval-uate the stability of power systems with power electronic components.However,conventional turbo-generator impedance models,such as the RL equivalent impedance model,only address the electrical aspects of turbo-generators and neglect the influence of shafting char-acteristics,potentially leading to inaccurate analysis re-sults.To address this issue,a turbo-generator impedance model is introduced which incorporates shafting charac-teristics validated through frequency scanning methods.Focusing on the turbo-generator and MMC-HVDC interconnection system,the oscillation analysis results are compared using the developed and traditional impedance models.The findings indicate that the developed model exhibits greater applicability and accuracy for power systems incorporating electronic equipment.Furthermore,a virtual damping control strategy for MMC-HVDC based on modulation links is developed to mitigate oscillation issues.The efficacies of the proposed impedance model and control strategy are validated in the tur-bo-generator and MMC-HVDC interconnection system.展开更多
With the rapid development of hydropower in the southwest of China, the energy transmitted by ultra high volt- age direct current (UHVDC) is ever increasing. At the same time, the power grid continues to expand westwa...With the rapid development of hydropower in the southwest of China, the energy transmitted by ultra high volt- age direct current (UHVDC) is ever increasing. At the same time, the power grid continues to expand westward, creating a service area. The stability of the Southwest China Power Grid is becoming a major issue. It is necessary to coordinate the development of hydropower and the construction of cross-region interconnections to optimize the grid structure. The Yu-E denotes the connection between the two region Yu (Chongqing) and E (Hubei) in China. The Yu-E project is a back-to-back voltage source converter based high voltage direct current (VSC-HVDC) project designed to realize an asynchronous connection of the Southwest and Central China Power Grids. The project will improve the bi-directional power support capability and optimize the grid structure. In addition, the Yu-E project will improve hydropower cross-region transmission capacity and enable the Southwest China Power Grid to utilize the power from the Three Gorges in the Central China Power Grid. In this paper, the fault isolation, low-frequency oscillation, sub-synchronous oscillation and short-circuit level are investigated and analyzed. Meanwhile, the impact of the Yu-E project on AC systems is studied in detail. In the end, the overall system design of the Yu-E project is introduced. The research results show that the Yu-E project can increase the transmission capability of the Southwest and Central China Power Grids, and enhance the stability of asynchronously interconnected AC systems. At the same time, the Yu-E project also serves as a demonstration project for the future development and application of VSC technology for the world.展开更多
基金supported by the Key Project of National Natural Science Foundation of China(No.51937001,No.52125704,and No.52307192).
文摘The rapid advancement of modular multi-level converter-based high-voltage direct current(MMC-HVDC)interconnection projects may lead to torsional vibrations in turbo-generator shafts,causing oscillations that pose operational risks to the power system.Impedance-based analysis is an effective method to eval-uate the stability of power systems with power electronic components.However,conventional turbo-generator impedance models,such as the RL equivalent impedance model,only address the electrical aspects of turbo-generators and neglect the influence of shafting char-acteristics,potentially leading to inaccurate analysis re-sults.To address this issue,a turbo-generator impedance model is introduced which incorporates shafting charac-teristics validated through frequency scanning methods.Focusing on the turbo-generator and MMC-HVDC interconnection system,the oscillation analysis results are compared using the developed and traditional impedance models.The findings indicate that the developed model exhibits greater applicability and accuracy for power systems incorporating electronic equipment.Furthermore,a virtual damping control strategy for MMC-HVDC based on modulation links is developed to mitigate oscillation issues.The efficacies of the proposed impedance model and control strategy are validated in the tur-bo-generator and MMC-HVDC interconnection system.
基金This work was supported in part by the National Natural Science Foundation of China(No.U1866210).
文摘With the rapid development of hydropower in the southwest of China, the energy transmitted by ultra high volt- age direct current (UHVDC) is ever increasing. At the same time, the power grid continues to expand westward, creating a service area. The stability of the Southwest China Power Grid is becoming a major issue. It is necessary to coordinate the development of hydropower and the construction of cross-region interconnections to optimize the grid structure. The Yu-E denotes the connection between the two region Yu (Chongqing) and E (Hubei) in China. The Yu-E project is a back-to-back voltage source converter based high voltage direct current (VSC-HVDC) project designed to realize an asynchronous connection of the Southwest and Central China Power Grids. The project will improve the bi-directional power support capability and optimize the grid structure. In addition, the Yu-E project will improve hydropower cross-region transmission capacity and enable the Southwest China Power Grid to utilize the power from the Three Gorges in the Central China Power Grid. In this paper, the fault isolation, low-frequency oscillation, sub-synchronous oscillation and short-circuit level are investigated and analyzed. Meanwhile, the impact of the Yu-E project on AC systems is studied in detail. In the end, the overall system design of the Yu-E project is introduced. The research results show that the Yu-E project can increase the transmission capability of the Southwest and Central China Power Grids, and enhance the stability of asynchronously interconnected AC systems. At the same time, the Yu-E project also serves as a demonstration project for the future development and application of VSC technology for the world.
