According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are ins...According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are inserted into IEEE-RTS79 reliability system for risk assessment. By the probabilistic load flow calculated by Monte Carlo simulation method, the probability of the accident is derived, and bus voltage and branch power flow overload risk index are defined in this paper. The results show that this method can realize the modeling of the correlation of wind power output, and the risk index can identify the weakness of the system, which can provide reference for the operation and maintenance personnel.展开更多
Based on risk theory, considering the probability of an accident and the severity of the sequence, combining N-1 and N-2 security check, this paper puts forward a new risk index, which uses the amount of optimal load ...Based on risk theory, considering the probability of an accident and the severity of the sequence, combining N-1 and N-2 security check, this paper puts forward a new risk index, which uses the amount of optimal load shedding as the severity of an accident consequence to identify the critical lines in power system. Taking IEEE24-RTS as an example, the simulation results verify the correctness and effectiveness of the proposed index.展开更多
The effects of CEC passes, isothermal holding time and reheating temperature on the microstructure evolution and grain coarsening behaviour of AZ61 magnesium alloy produced by the recrystallisation and partialmelting ...The effects of CEC passes, isothermal holding time and reheating temperature on the microstructure evolution and grain coarsening behaviour of AZ61 magnesium alloy produced by the recrystallisation and partialmelting （RAP） process were investigated. Before partial remelting, as-cast AZ61 alloy was deformed by cyclic extrusion compression （CEC） with one pass and two pass at 330 ℃. After CEC, the microstructure consisted of unrecrystallized grains and deformed eutectic compounds. Increasing isothermal holding time resulted in the formation of spheroidal grains surrounded by liquid films. With increasing the isothermal holding time, the solid grain size increased and the degree of spheroidization was improved. With increasing the reheating temperature, namely increasing liquid fraction, the solid grain size obviously decreased during the period from 560 ℃ to 570 ℃ and then slightly increased after 570 ℃, while the shape factor increased monotonously. During partial remelting, increasing reheating temperature can properly short the isothermal holding time to obtain fine structure. Moreover, increasing the numbers of CEC passes could produce finer semi-solid microstructure. The coarsening behavior of solid grains in the semi-solid state obeys Ostwald ripening and grain coalescence mechanisms. The coarsening rate constant, K, 595 ℃. After CEC plus partial remelting, the ideal and fine was suitable for thixoforming. was 80μm^3.s^-1 for samples partially remelted at semi-solid state structure can be obtained, which展开更多
文摘According to the characteristics of the correlation of multiple wind farm output, this paper put forwards a modeling method based on fuzzy c-means clustering and the copula function, and correlation wind farms are inserted into IEEE-RTS79 reliability system for risk assessment. By the probabilistic load flow calculated by Monte Carlo simulation method, the probability of the accident is derived, and bus voltage and branch power flow overload risk index are defined in this paper. The results show that this method can realize the modeling of the correlation of wind power output, and the risk index can identify the weakness of the system, which can provide reference for the operation and maintenance personnel.
基金Technology Major Project of China Southern Power Grid Co.,Ltd.(GZ2014-2-0049).
文摘Based on risk theory, considering the probability of an accident and the severity of the sequence, combining N-1 and N-2 security check, this paper puts forward a new risk index, which uses the amount of optimal load shedding as the severity of an accident consequence to identify the critical lines in power system. Taking IEEE24-RTS as an example, the simulation results verify the correctness and effectiveness of the proposed index.
文摘The effects of CEC passes, isothermal holding time and reheating temperature on the microstructure evolution and grain coarsening behaviour of AZ61 magnesium alloy produced by the recrystallisation and partialmelting （RAP） process were investigated. Before partial remelting, as-cast AZ61 alloy was deformed by cyclic extrusion compression （CEC） with one pass and two pass at 330 ℃. After CEC, the microstructure consisted of unrecrystallized grains and deformed eutectic compounds. Increasing isothermal holding time resulted in the formation of spheroidal grains surrounded by liquid films. With increasing the isothermal holding time, the solid grain size increased and the degree of spheroidization was improved. With increasing the reheating temperature, namely increasing liquid fraction, the solid grain size obviously decreased during the period from 560 ℃ to 570 ℃ and then slightly increased after 570 ℃, while the shape factor increased monotonously. During partial remelting, increasing reheating temperature can properly short the isothermal holding time to obtain fine structure. Moreover, increasing the numbers of CEC passes could produce finer semi-solid microstructure. The coarsening behavior of solid grains in the semi-solid state obeys Ostwald ripening and grain coalescence mechanisms. The coarsening rate constant, K, 595 ℃. After CEC plus partial remelting, the ideal and fine was suitable for thixoforming. was 80μm^3.s^-1 for samples partially remelted at semi-solid state structure can be obtained, which
