CN100388591C - Method for encoding and decoding group code in large code distance in signal transmission of relay protection - Google Patents

Abstract

The present invention relates to a method for encoding and decoding group codes with large code distances during relay protection signal transmission, which mainly solves the problems that the carrier communication in the prior art is easy to disturb, the error rate is high, etc. The coding method comprises the steps that the code words of one set of group codes are selected and stored in a memory of a transmitter; a relay signal collector of a power system samples relay protection command signals; the corresponding code words of sampled results in the group codes are found out according to the sampled results; a microprocessor of the transmitter sends data frames formed by adding bytes of frame heads, frame types, etc. on the found code words to the opposite side. The decoding process and the coding process are reverse mutually. The method of the present invention has the advantages of strong error correction capability, high decoding correction rate, etc. and is suitable for the relay protection signal transmission of the power system.

Description

Big code distance block code decoding method in a kind of relay protection signal transmission

Technical field

The present invention relates to the power system automation technology field, relate in particular to the big code distance block code decoding method in a kind of relay protection signal transmission.

Background technology

In China,, generally adopt the main protection of carrier current protection as the reflection fault for the extra high voltage network of 220kV and minority 110kV and the above electric pressure of 220kV.The type of the carrier current protection of transmission line has a lot, mainly contains: four types of mutually differential carrier current protection, direction carrier current protection, high frequency locking distance (zero sequence) protection and transfer trip carrier current protections.The operation principle of carrier current protection is: the application communication technology; adopt optical fiber, transmission line or microwave etc. as passage; differentiation result or the circuit both sides power frequency electric parameters measured in the stage protection in both sides are transferred to the opposite end, and the opposite end judges in view of the above so that protective relaying device is taked corresponding action.

In carrier current protection, relay protection signal reliably, accurately the transmission be the key of carrier current protection.Existing transmission technology is generally:

1) ZAP, as passage, the high-frequency electric wave upper edge passage that electric parameters is modulated at 50～400kHz transmits mutually with transmission line itself.This method shortcoming is that power transmission line is subjected to various interference easily, and signal transmission time is longer.

2) Digital Signal Processing and optical communication technique, employing optical fiber is passage, and light signal is a carrier, and this method has utilized light signal not to be subjected to interference such as electromagenetic wave radiation, and transmission rate is very fast, can reach very high reliability and transmission speed.Along with the reduction of optical fibre installation cost, the more and more application of this technology is in the transmission of guard signal.But, existing generally adopt the amount of information of 1bit as one road signal with the encoding and decoding in the optical signal transmission, at this moment code distance is less, and under the error rate reached 10 situation, the error of transmission situation just was 10 like this, and this is to be difficult to permission in relaying protection.

Summary of the invention

In order to overcome the deficiencies in the prior art, the object of the present invention is to provide the big code distance block code decoding method in a kind of relay protection signal transmission, to improve the reliability of guard signal encoding and decoding technique.

For finishing above-mentioned purpose, the overall technological scheme that the present invention takes is: the big code distance block code coding method in the relay protection signal transmission may further comprise the steps:

The code word of step 1, selection one component group code is stored in the memory of transmitter;

The relay signal picker of step 2, electric power system is sampled to the relaying protection command signal;

Step 3, according to sampled result, find out sampled result corresponding code word in block code;

The microprocessor of step 4, transmitter adds the code word of finding out bytes composition Frames such as frame head and frame type are sent to offside.

Big code distance block code decoder method in the relay protection signal transmission may further comprise the steps:

Step 1, receiver are separated frame to the Frame that receives, and will order code word to be separated;

Step 2, to code word decipher and with the storage code word compare, consider that electric power system is to protection fail safe and reliability requirement, in conjunction with the strong characteristics of block code error correcting capability, suitable permission error code position is set, just can under the fail safe that requires, obtain desirable reliability;

Step 3, according to the error code position that allows, obtain correct command signal;

Step 4, command signal is sent to protective device.

Above-mentioned described block code is 64 block codes; The code distance of above-mentioned described block code is 32.

The present invention has following advantage: the present invention adopts 64 block codes (RM sign indicating number) encoding and decoding technique.Simple structure, error correcting capability is strong, can design the RM sign indicating number of different code length as required.Having selected code distance among the present invention is 32 RM sign indicating number, and long code distance has been guaranteed the reliability of transmission.Because Reed (Reed) algorithm is the decoding algorithm that designs for the RM sign indicating number specially.It with the method for majority logic judgement from receiving the direct recovering information of vector, and not mistake in computation pattern.In the present invention, can correct 15 random errors.Decoding rate of the present invention is very high, and the correct decoding probability is near 1.

Description of drawings

Fig. 1 is the present invention's main flow chart of encoding;

Fig. 2 is data frame format figure;

Fig. 3 is the present invention's main flow chart of decoding.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is done explanation in further detail.

See also Fig. 1.Main flow chart of the present invention.At first, carry out the block code coding, Methods for Coding is:

The first step selects the code word of a component group code to be stored in the memory of transmitter earlier.It is RM sign indicating number encoding and decoding technique that the present invention adopts 64 block codes.The RM sign indicating number is the important sign indicating number class of in the linear block codes, and its simple structure, and error correcting capability is strong, can design the RM sign indicating number of different code length as required.Therefore how to select correct code word to realize that the coding of guard signal and decoding are particularly important.Having selected code distance among the present invention is 32 RM sign indicating number, and long code distance has been guaranteed the reliability of transmission.Reed (Reed) algorithm is the decoding algorithm that designs for the RM sign indicating number specially.It is with the method for majority logic judgement from receiving the direct recovering information of vector, and not mistake in computation pattern.The Reed algorithm can be corrected r rank RM sign indicating number RM[r, m] (1/2) * 2 of occurring ^M-r-1 random error, and recover k position information.In the present invention, can correct 15 random errors.

Because 1 rank (64,7) RM sign indicating number minimum distance related among the present invention is 32, error correcting capability is 15, so error code can be corrected within 15.Its correct decoding probability is:

$Q={(1-p_e)}^{64}+\left(\begin{array}{c}64\\ 1\end{array}\right)p_e{(1-p_e)}^{63}+\left(\begin{array}{c}64\\ 2\end{array}\right){p_e}^2{(1-p_e)}^{62}+L+\left(\begin{array}{c}64\\ 15\end{array}\right){p_e}^{15}{(1-p_e)}^{49}$

With pe=10 substitution following formula, obtain the correct decoding probability and be about 1.Probability that can not correct decoding is 2.2204 * 10 ^-16Hence one can see that, and according to this computational methods, the Mean Time Between Replacement that mistake says the word is

$\mathrm{\τ}=\frac{(1.25\×{10}^{-3}/80)\×64/2.2204\×{10}^{-16}}{3600\×24\×365}\≈142810$ (year)

In second step, the relay signal picker of electric power system is sampled to the relaying protection command signal, and what relaying protection was come is contact point signal, and collector carries out real-time sampling to it, and sampled result is sent into processing module;

The 3rd step according to sampled result, obtained current relaying protection state information, found its code word corresponding in stored packet sign indicating number according to different state informations;

In the 4th step, the microprocessor of transmitter adds the code word of finding out bytes composition Frames such as frame head and frame type send to transmission channel.

Decoding is the inverse process of coding, and coding/decoding method of the present invention is as follows:

Step 1, receiver are separated frame to the Frame that receives, and remove frame head and supplementary 64 order of the bit code words are separated;

Step 2, processor carry out getting algorithm decoding in the RM sign indicating number to code word, and this algorithm speed of service comparatively fast can be corrected 15 random error sign indicating numbers.

Step 3, owing to consider fail safe, the code word of decode results and storage is compared, in the scope that allows error code, recover command information, utilize the error correcting capability of RM sign indicating number can obtain higher reliability like this, the error code figure place is set simultaneously improves its fail safe, this two aspect all is greatly improved;

Step 4, output are given line protective devices with the coomand mode information that obtains.

It should be noted last that: above embodiment is the unrestricted technical scheme of the present invention in order to explanation only, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the art is to be understood that: still can make amendment or be equal to replacement the present invention, and not breaking away from any modification or partial replacement of the spirit and scope of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (4)

1. the big code distance block code coding method during a relay protection signal transmits is characterized in that this method may further comprise the steps:

The code word of step 1, selection one component group code is stored in the memory of transmitter;

The relay signal picker of step 2, electric power system is sampled to the relaying protection command signal;

Step 3, according to sampled result, find out sampled result corresponding code word in block code;

The microprocessor of step 4, transmitter adds that with the code word of finding out frame head and frame type byte composition Frame are sent to offside.

2. the big code distance block code coding method in the relay protection signal transmission according to claim 1 is characterized in that the block code in the described step 1 is 64 block codes.

3. the big code distance block code coding method in the relay protection signal transmission according to claim 2 is characterized in that the code distance of described block code is 32.

4. the big code distance block code decoder method during a relay protection signal transmits is characterized in that this method may further comprise the steps:

Step 1, receiver are separated frame to the Frame that receives, and will order code word to be separated;

Step 2, to code word decipher and with the storage code word compare;

Step 3, solve command signal;

Step 4, command signal is sent to protective device.

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