Abstract
In order to improve the reliability of fault identification of the double-circuit transmission lines on the same tower, a new algorithm for fast protection of double-circuit transmission lines on the same tower based on the reactive powers of traveling wave is proposed. With the implementation of S-transform, the initial traveling wave reactive powers are calculated and the change characteristics of reactive power under different fault conditions are studied. The protection criterion is constructed by analyzing the ratio of the reactive powers of the same end on double-circuit transmission lines and the ratio of the reactive powers at both ends on the same line. According to the ratio of reactive power on the same side of the line and both ends of the same line, it is possible to identify whether the faults of the double-circuit line of the same tower occurred in or out of the protection zone. A large number of simulation results show that the protection performance is sensitive and reliable, and quick to respond. The criterion is simple and is basically not affected by fault initial angles, fault types, and transitional resistances.
Highlights
With the advantages of saving investment cost and effectively improving power transmission capacity, the double circuit transmission lines on the same tower have been widely used in China’s high-voltage power grid in [1]
Based on the research ideas of literature [14] [15] [16], this paper proposes a new fault identification principle based on reactive power of the traveling wave on double-circuit lines on the same tower
S-transform is a method of signal time-frequency joint analysis, and it is the development of continuous wavelet transform and short-time Fourier transform
Summary
With the advantages of saving investment cost and effectively improving power transmission capacity, the double circuit transmission lines on the same tower have been widely used in China’s high-voltage power grid in [1]. In [12], the fault current traveling wave characteristics on the double-circuit line on the same tower are analyzed, but no specific circuit protection scheme is proposed. The literature [13] used the characteristics of inconsistent traveling wave speeds when a metallic fault on the same tower occured and proposed a differential protection scheme for traveling wave on the same tower double circuit line. Based on the research ideas of literature [14] [15] [16], this paper proposes a new fault identification principle based on reactive power of the traveling wave on double-circuit lines on the same tower. The S-transform is used to extract the single-frequency initial voltage and current traveling wave after the fault occurs. If t0 is the traveling wave arrives at bus M from the fault point for the first time, t1 is the second time the traveling wave arrives at M after the wave reflection occurs, the fault traveling wave acquired by R1 is called the initial voltage and current traveling wave in time-slot t0 t1 in [14]
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