Discrimination method for three-phase short-circuit faults of UHV AC transmission lines based on single-ended electrical quantities
A technology of UHV AC and transmission lines, which is applied in the direction of electrical components, measuring electric variables, emergency protection circuit devices, etc., and can solve the effects of affecting the operating performance of impedance relays, poor resistance to transition resistance of impedance relays, and the impact of impedance distance protection on operating performance issues that cannot be ignored
Active Publication Date: 2018-11-06
STATE GRID CORP OF CHINA +2
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Problems solved by technology
Considering the influence of the ground capacitance along the line, the relationship between the fault impedance and the fault distance is a hyperbolic tangent function. The characteristics of the hyperbolic tangent function determine that the resistance of the impedance relay is poor, and the additional impedance brought by the transition resistance will seriously affect the impedance of the impedance relay. action performance
The ultra-voltage AC transmission line transmits large-capacity electric energy, and it is a heavy-duty transmission line. The heavy-load current will reduce the action sensitivity of the impedance distance protection, and the impact of the heavy-load current on the action performance of the impedance distance protection cannot be ignored.
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[0017] The technical solution of the present invention will be further described in detail according to the accompanying drawings.
[0018] figure 1 It is a schematic diagram of the UHV AC line power transmission system applying the present invention. figure 1 CVT is a voltage transformer, and CT is a current transformer. The protection device samples the voltage of the voltage transformer CVT and the current waveform of the current transformer CT at the protection installation place of the UHV AC transmission line to obtain the instantaneous values of voltage and current.
[0019] The protection device uses the Fourier algorithm to calculate the three-phase voltage of the UHV AC transmission line in normal operation on the sampled instantaneous values of voltage and current and three-phase current Among them, φαβ=ABC, BCA, CAB phase; that is, if φ is A phase, α is B phase, and β is C phase; if φ is B phase, α is C phase, and β is A phase; if φ is C phase, α is the A...
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The invention discloses an ultra-high voltage AC transmission line three-phase short circuit fault distinguishing method based on single-end electric quantity. Three-phase short circuit fault happens to an ultra-high voltage AC transmission line protection setting range, an angle of an inter-phase voltage at a protection mounting place when the ultra-high voltage AC transmission line operates normally ahead of an inter-phase voltage at the ultra-high voltage AC transmission line protection setting range after the three-phase short circuit fault happens to the ultra-high voltage AC transmission line falls in a range (90DEG 270 DEG), an angle of an another-phase voltage at the protection mounting place when the ultra-high voltage AC transmission line operates normally ahead of an another-phase voltage at the ultra-high voltage AC transmission line protection setting range after the three-phase short circuit fault happens to the ultra-high voltage AC transmission line falls in a range (90DEG 270 DEG), and when the above three conditions are true at the same time, the ultra-high voltage AC transmission line three-phase short circuit fault can be accurately distinguished, and influences of factors such as transition resistance, load current, a power system operation mode and the like on performance of a protection action can be eliminated.
Description
technical field [0001] The invention relates to the technical field of relay protection of power systems, in particular to a method for judging three-phase short-circuit faults of UHV AC transmission lines based on single-ended electrical quantities. Background technique [0002] The power frequency variation distance protection constitutes the distance protection by reflecting the sudden change of the working voltage amplitude. This method has the advantages of being less affected by the operation mode of the power system and having a strong ability to resist transition resistance. However, since the mutation of the working voltage amplitude used in this method only exists in the initial stage of the fault, it cannot be used as a backup protection for EHV / UHV AC transmission lines. [0003] Impedance distance protection reflects the fault distance length according to the fault impedance to distinguish whether the fault point is inside the protection zone or outside the prot...
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IPC IPC(8): H02H7/26G01R31/02
Inventor 曾惠敏
Owner STATE GRID CORP OF CHINA