To avoid the impact of the transient saturation of a current transformer, a fast busbar protection method based on the initial traveling wave integrated active power differential principle is proposed in this paper. The Peterson equivalent model is applied to analyze the initial traveling wave distribution characteristics of the internal and external faults of the busbar. The initial traveling wave active powers of each sampling point on each transmission line connected to the busbar are calculated with the implementation of an S-transform. By introducing the integrated active power actuating quantity and active power braking quantity, a protection criterion with a characteristic braking ratio is proposed. The theoretical analysis and experimental simulation results show that the protection performance is sensitive and reliable, with a quick response and simple criterion, and is essentially not susceptible to the impacts of the initial fault angle, fault type, and fault resistance. INDEX TERMS Busbar protection, initial traveling wave, integrated active power, braking ratio, S-transform.

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To overcome the contradiction between speed and reliability in existing busbar protection schemes, a new busbar protection algorithm based on a polarity comparison of fundamental frequency currents is proposed. The algorithm extracts the fundamental frequency components of the fault reference current and the virtual current through a wavelet transform. The angle between the two currents is used to characterize the polarity relationship. The polarities of the virtual current and the reference current are the same when an internal fault occurs, and the angle will be small. The polarities of the two currents are opposite for an external fault, in which case the angle is larger. By analysing the variation characteristics of the angle between faults inside and outside busbar, a protection criterion is established, and the fault area is determined. In simulation results based on PSCAD/EMTDC, the algorithm can quickly and reliably identify the faults inside and outside the busbar area, and its performance is not affected by the initial fault angle, fault resistance, fault type or capacitor voltage transformer (CVT) transmission characteristics.

According to the traveling-wave theory, this paper presents a new busbar protection algorithm based on the comparison of the initial traveling wave power. The algorithm analyzes the distribution characteristics of the initial traveling wave when internal and external busbar faults occur and calculates the traveling wave reactive power of multiple sampling points of the initial traveling wave based on S-transform. And, accordingly, the concept of integrated reactive power is proposed. The protection criterion is established based on the comparison of the initial traveling wave integrated reactive power magnitude of each associated transmission line connected to the busbar. When an internal busbar fault occurs, the initial traveling wave integrated reactive power of each associated transmission line connected to the busbar is infinitesimally small and approximately equal; when an external busbar fault occurs, the initial traveling wave integrated reactive power of the faulted transmission line connected to the busbar exists and the values are much larger than that of the non-faulted transmission lines. By comparing the relative magnitudes of the initial traveling wave integrated reactive power of each associated transmission line connected to the busbar, a clear distinction between internal and external busbar faults can be made. Theoretical analysis, along with simulation experiments, indicates that the proposed method of performance assessment for busbar protection is sensitive, reliable, quick to respond, and easy to distinguish, and would not be affected by the influence of fault initial angles, fault types, transitional resistances, and other factors.Hao Wu (Non-member) received the Ph.D. degree in the automation of electric power systems from Southwest Jiaotong University, Chengdu, China, in 2016. He is presently an Associate Professor with the School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong, China. His research interests include power system protection and control and power systems simulation and modeling.Xingxing Dong (Non-member) received the B.Sc. degree in electrical engineering and automation from the

Transmission lines are an important part of the power system and the main artery for the transmission of electrical energy. The safe operation of overhead lines is critical to the safe and stable operation of the entire power grid. This paper takes the main body of the transmission conductor as the main research object. According to the line load calculation theory, risk assessment theory and fuzzy prediction theory, first establish a transmission line risk assessment model that takes into account the influence of temperature changes under weather forecast, and then uses the GA optimized TS-FNN The prediction of the sag of the transmission line has verified the feasibility and accuracy of the proposed theory and method through simulation analysis.