During the transient period of large-disturbance of the received power grid, the power features of the inverter are of great important for the security and stability of the system. The research before is defective in ...During the transient period of large-disturbance of the received power grid, the power features of the inverter are of great important for the security and stability of the system. The research before is defective in that the constant control mode assumption and the rough HVDC simulation model. The paper establishes the PSCAD/EMTDC model for Yun-Guang EHVDC system, and analysis the transient real power and the reactive power of the inverter. With the analysis of logic for control mode, the author also introduces the physical processes of the peak of the reactive power. At last, the paper puts forward several strategies for suppressing the peak of the dynamic reactive power and real power recovery acceleration.展开更多
HVDC technology has been widely used in modern power system. On one hand, HVDC has the advantages of economy, high efficiency and strong controllability. While on the other hand, it makes the dynamic characteristics o...HVDC technology has been widely used in modern power system. On one hand, HVDC has the advantages of economy, high efficiency and strong controllability. While on the other hand, it makes the dynamic characteristics of the power system becoming more and more complex. That puts forward a new challenge to system stability and raises new questions for power system simulation. This paper focuses on the interaction between AC and DC systems, especially the problem of commutation failure caused by AC system fault. Based on the data of China Southern Power Grid, this paper calculates the fault regions that may cause commutation failure and calculates the system critical clearance time under different load models, analyzes the impacts of different load models on commutation failure and the stability of AC/DC hybrid system.展开更多
A new inductive motors load equivalence algorithm based on coherence is proposed in this paper. In order to partite motors load rapidly and accurately, fuzzy c-means clustering along with particle swarm optimization (...A new inductive motors load equivalence algorithm based on coherence is proposed in this paper. In order to partite motors load rapidly and accurately, fuzzy c-means clustering along with particle swarm optimization (PSO-FCM) algorithm is proposed to identify coherent motors base on its physical essence of fuzziness. The merits of PSO algorithm are independent to initial value and convergent to optimum value rapidly, and the validity function is constructed to assess clustering validity. The test on IEEE 39-Bus System is presented to evaluate the effectiveness of the new algorithm, the membership matrix definite not only coherence group of motors but also correlation value of coherence between motors. The algorithm can be used to partite motor load based on coherency in dynamic equivalence with power system operating on different modes.展开更多
The paper firstly interprets the differences between electromechanical transients program BPA and electromagnetic transients program EMTDC in the field of principle, model and algorithm. Then the authors carry out the...The paper firstly interprets the differences between electromechanical transients program BPA and electromagnetic transients program EMTDC in the field of principle, model and algorithm. Then the authors carry out the simulation based on single-machine infinite-bus system and draw some conclusions. The time consumption of the simulation using EMTDC is much longer than the simulation using BPA under the same length of time. The results of BPA are close to those of EMTDC under steady conditions. The fundamental frequency component of the EMTDC results seems closer to the BPA results than its original value, but they still away from completely consistent. In this simulation of single-machine infinite-bus system, the transient stability results of BPA and EMTDC are close, but the results of BPA are apt to be more conservative. All the conclusions above have a certain reference value to both hybrid simulation and comprehensive analysis method in the study of the AC/DC digital simulation of large power grid.展开更多
文摘During the transient period of large-disturbance of the received power grid, the power features of the inverter are of great important for the security and stability of the system. The research before is defective in that the constant control mode assumption and the rough HVDC simulation model. The paper establishes the PSCAD/EMTDC model for Yun-Guang EHVDC system, and analysis the transient real power and the reactive power of the inverter. With the analysis of logic for control mode, the author also introduces the physical processes of the peak of the reactive power. At last, the paper puts forward several strategies for suppressing the peak of the dynamic reactive power and real power recovery acceleration.
文摘HVDC technology has been widely used in modern power system. On one hand, HVDC has the advantages of economy, high efficiency and strong controllability. While on the other hand, it makes the dynamic characteristics of the power system becoming more and more complex. That puts forward a new challenge to system stability and raises new questions for power system simulation. This paper focuses on the interaction between AC and DC systems, especially the problem of commutation failure caused by AC system fault. Based on the data of China Southern Power Grid, this paper calculates the fault regions that may cause commutation failure and calculates the system critical clearance time under different load models, analyzes the impacts of different load models on commutation failure and the stability of AC/DC hybrid system.
文摘A new inductive motors load equivalence algorithm based on coherence is proposed in this paper. In order to partite motors load rapidly and accurately, fuzzy c-means clustering along with particle swarm optimization (PSO-FCM) algorithm is proposed to identify coherent motors base on its physical essence of fuzziness. The merits of PSO algorithm are independent to initial value and convergent to optimum value rapidly, and the validity function is constructed to assess clustering validity. The test on IEEE 39-Bus System is presented to evaluate the effectiveness of the new algorithm, the membership matrix definite not only coherence group of motors but also correlation value of coherence between motors. The algorithm can be used to partite motor load based on coherency in dynamic equivalence with power system operating on different modes.
文摘The paper firstly interprets the differences between electromechanical transients program BPA and electromagnetic transients program EMTDC in the field of principle, model and algorithm. Then the authors carry out the simulation based on single-machine infinite-bus system and draw some conclusions. The time consumption of the simulation using EMTDC is much longer than the simulation using BPA under the same length of time. The results of BPA are close to those of EMTDC under steady conditions. The fundamental frequency component of the EMTDC results seems closer to the BPA results than its original value, but they still away from completely consistent. In this simulation of single-machine infinite-bus system, the transient stability results of BPA and EMTDC are close, but the results of BPA are apt to be more conservative. All the conclusions above have a certain reference value to both hybrid simulation and comprehensive analysis method in the study of the AC/DC digital simulation of large power grid.
