Low-pass digital filtering method applicable to direct current line protection

A DC line, digital filtering technology, applied in emergency protection data processing device, emergency protection circuit device, emergency protection device parts and other directions, can solve power outage accidents, low-pass digital filter filtering characteristics are not ideal, DC transmission lines Backup protection malfunction and other problems, to achieve the effect of smooth passband, best effect, and good stopband attenuation

CN107046271AInactive Publication Date: 2017-08-15STATE GRID TIANJIN ELECTRIC POWER +1
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2017-08-15
Estimated Expiration
Not applicable · inactive patent

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Abstract

The present invention relates to a low-pass digital filter method suitable for DC line protection. Its technical features include the following steps: Step 1. Research and select a low-pass filter designed with a Kaiser window as a low-pass digital filter for DC line protection. Step 2, get β=7.865 in the Kaiser window function, N=21, calculate the coefficient of the Kaiser window low-pass digital filter; Step 3, multiply successively with the sampling value array x (n) of DC line protection Add the series of ω(n) to calculate the output series after filtering by the Kaiser window low-pass digital filter; step 4, send the series y(n) obtained by filtering into the program of DC line protection to perform protection judgment According to the calculation. The invention can accurately extract the DC components in the voltage and current from the sampling signals containing the DC components, transient high-frequency oscillation components and noise, provide correct measurement quantities for the backup protection of the DC line, and ensure the backup of the DC transmission line Selectivity of protective actions.
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Description

technical field

[0001] The invention belongs to the technical field of direct current line protection, in particular to a low-pass digital filtering method suitable for direct current line protection. Background technique

[0002] DC transmission has obvious advantages in long-distance large-capacity power transmission, submarine cable power transmission, and power system networking. Using DC transmission to realize asynchronous networking can not only obtain networking benefits, but also avoid problems caused by large power grids, and can also improve the operating performance of the original AC grid. DC line protection undertakes the task of quickly detecting and processing line faults. Whether it can act quickly and reliably in the event of a fault is related to the safe and stable operation of the entire power system.

[0003] At present, the domestic DC transmission projects that have been put into operation widely use traveling wave protection as the main protection o...

Examples

Embodiment Construction

[0032] Embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings:

[0033] A low-pass digital filtering method suitable for DC line protection, comprising the following steps:

[0034] Step 1, study and select the low-pass filter designed with Kaiser window as the low-pass digital filter for DC line protection;

[0035] Finite impulse response digital filter is the most widely used digital filter in relay protection, and its design methods include window function method, frequency sampling method and constrained least square method. Among them, the principle of the window function method is simpler and easier to implement. Typical window function methods include rectangular window, Hanning window, Hamming window, Bartlett window, Blackman window, triangular window, and Kaiser window.

[0036] The specific method of the step 1 is: by comparing the time domain shape diagram and the amplitude frequency of the rectan...