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In this study, a novel fault location algorithm applicable to the partial coupling four-parallel lines is presented. In this method, the occurrence of differential positive-sequence currents at local end are used to select the two parallel lines whose electrical data measured will be used to calculate the fault location. Then two objective functions established based on the assumption that the fault...
Sensitivity of start element impacts the performance of transmission line protection. Normally, start element is affected by data window length. A start element of transmission line relay protection based on current variation sample data of three phases at the same time is proposed in this paper. It includes two criterions. The start element performance is not impacted by data window and frequency...
For untransposed parallel transmission lines, the fault impedance measured by relays will be affected by both the mutual impedance between parallel lines and the coupling effect of different sequence components in the single line. Even the fault phase voltages are compensated by the zero-sequence current in the adjacent line, the errors of measured fault impedances are still quite large. The performance...
A maloperation prevention method of zero sequence direction longitudinal protection was presented in this paper directing at broken-line faults of double-circuit transmission lines on a same tower. Firstly, the maloperation reasons were analyzed in detail. Then, the zero sequence direction amplitude-comparison criterion and the negative sequence direction amplitude-comparison criterion were constructed...
This paper discusses the formation of unbalance current when series-compensated transmission lines operate normally, studies the principle of improving unbalance degree by adjusting the series-compensation capacity within relatively tight bounds of each phase, proposes the method of series compensation parameters based on Nelder-Mead algorithm. A simulation model of 750kV transmission lines was constructed...
Current differential protection widely used in transmission line based on comparing sum and difference of two side current phasors. Its sensitivity was impact by load current. A current differential protection based on virtual restraint current was proposed. The virtual current contains phase information of the bigger current and amplitude information of the smaller current. The sensitivity of criterion...
When a fault occurs on a transmission line, fault generated high frequency transient components are a series of natural frequencies in frequency domain. This paper proposes a protection algorithm for EHV (Extra High Voltage) transmission line based on spectrum characteristic of natural frequency. Spectrum correlation coefficient is used to determine whether a fault is internal or external fault. It...
The identification methods of sample value (SV) distortion are proposed in this paper to avoid protection mal-operation in smart substations. The methods contain abnormity identification using data from same sources, using relevant data, and according to data features. The same source data include the double A/D data of one merging unit (MU), doubled communication networks of one protection, and doubled...
This paper proposes a new scheme of substation area backup protection system based on substation area range of information. A configuration scheme of relay protection in smart substation was proposed firstly, the structure of substation area backup protection (SABP) was introduced, the information matrix of SABP which can reflect the substation topology was established, the protection algorithm of...
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