The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the syste...The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the system.The traditional protection principles are unsuitable for RMGs due to the flexibility of RMG operation,the complexity of RMG topology,and the variety of fault control strategies of inverter-interfaced distributed generators(IIDGs).The traditional fault component protection principle is affected by the low voltage ride-through(LVRT)control strategy and will fail in some scenarios.In order to make the fault component protection principle available in every scenario,a current-based fault control strategy is proposed.Specific fault characteristics are generated by the grid-feeding IIDGs during the fault so they can be equivalent to the open circuits,and the fault models in additional network can be simplified.By analyzing the fault characteristics,an RMG protection strategy based on the current-based fault control of IIDGs is presented.The fault directions of feeders can be distinguished and the fault feeder can be located accurately in both grid-connected and islanded RMGs.Then,the grid-feeding IIDGs can transit to LVRT mode smoothly.Thus,IIDGs are considered comprehensively in terms of coordinating with fault control and fault characteristic generation.Finally,the experimental results of the hardware platform prove the effectiveness of the proposed current-based fault control strategy,and the simulation results based on PSCAD/EMTDC verify the correctness of the protection strategy.展开更多
Recently, the smart grid has been considered as a next-generation power system to modernize the traditional grid to improve its security, connectivity, efficiency and sustainability.Unfortunately, the smart grid is su...Recently, the smart grid has been considered as a next-generation power system to modernize the traditional grid to improve its security, connectivity, efficiency and sustainability.Unfortunately, the smart grid is susceptible to malicious cyber attacks, which can create serious technical, economical, social and control problems in power network operations. In contrast to the traditional cyber attack minimization techniques, this paper proposes a recursive systematic convolutional(RSC) code and Kalman filter(KF) based method in the context of smart grids.Specifically, the proposed RSC code is used to add redundancy in the microgrid states, and the log maximum a-posterior is used to recover the state information, which is affected by random noises and cyber attacks. Once the estimated states are obtained by KF algorithm, a semidefinite programming based optimal feedback controller is proposed to regulate the system states, so that the power system can operate properly. Test results show that the proposed approach can accurately mitigate the cyber attacks and properly estimate and control the system states.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.22120210164).
文摘The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the system.The traditional protection principles are unsuitable for RMGs due to the flexibility of RMG operation,the complexity of RMG topology,and the variety of fault control strategies of inverter-interfaced distributed generators(IIDGs).The traditional fault component protection principle is affected by the low voltage ride-through(LVRT)control strategy and will fail in some scenarios.In order to make the fault component protection principle available in every scenario,a current-based fault control strategy is proposed.Specific fault characteristics are generated by the grid-feeding IIDGs during the fault so they can be equivalent to the open circuits,and the fault models in additional network can be simplified.By analyzing the fault characteristics,an RMG protection strategy based on the current-based fault control of IIDGs is presented.The fault directions of feeders can be distinguished and the fault feeder can be located accurately in both grid-connected and islanded RMGs.Then,the grid-feeding IIDGs can transit to LVRT mode smoothly.Thus,IIDGs are considered comprehensively in terms of coordinating with fault control and fault characteristic generation.Finally,the experimental results of the hardware platform prove the effectiveness of the proposed current-based fault control strategy,and the simulation results based on PSCAD/EMTDC verify the correctness of the protection strategy.
文摘Recently, the smart grid has been considered as a next-generation power system to modernize the traditional grid to improve its security, connectivity, efficiency and sustainability.Unfortunately, the smart grid is susceptible to malicious cyber attacks, which can create serious technical, economical, social and control problems in power network operations. In contrast to the traditional cyber attack minimization techniques, this paper proposes a recursive systematic convolutional(RSC) code and Kalman filter(KF) based method in the context of smart grids.Specifically, the proposed RSC code is used to add redundancy in the microgrid states, and the log maximum a-posterior is used to recover the state information, which is affected by random noises and cyber attacks. Once the estimated states are obtained by KF algorithm, a semidefinite programming based optimal feedback controller is proposed to regulate the system states, so that the power system can operate properly. Test results show that the proposed approach can accurately mitigate the cyber attacks and properly estimate and control the system states.
