JPH06351149A - Digital protective relay - Google Patents

Abstract

PURPOSE:To recover immediately the fault of an analog circuit, by sampling inputted analog data, and by correcting A/D-converted digital data, and further, by performing the storage of the correcting values thereof, and moreover, by performing automatically protective operations through a computing circuit from its inputted data while using the correcting values. CONSTITUTION:An analog input circuit 1 performs the level conversions of the inputted analog data of a plurality of system electric quantities by respective transformers 11, and it removes higher harmonics from the analog data by filter circuits 12, and then, it samples and holds of the analog data at a predetermined time-interval by sampling-hold circuits 13, and further, it inputs the sampled data to a multiplexer 14. Subsequently, the analog input circuit 1 reads out in succession the analog data from the multiplexer 14, and it performs the A/D conversions of the read analog data by an A/D conversion circuit 15, and then, it corrects the errors of the read analog data by a correcting-value storage circuit 16, and further, it stores the resultant correcting values in the circuit 16. Using the outputs of the A/D conversion circuit 15 and the correcting-value storage circuit 16, a computing circuit 2 performs predetermined protective operations, and when the operational results satisfy operating conditions, it outputs a tripping command to a circuit breaker via an output circuit 4. Thereby, in case of the fault of the input circuit 1, its quick replacement-recovery work is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital protective relay device for protecting a power system, and more particularly to a digital protective relay device having a function of correcting an error in an analog input section.

[0002]

2. Description of the Related Art A conventional digital protective relay device will be described with reference to FIG. As shown in FIG. 4, for example, a current from the power system is input to the analog input circuit 1. The arithmetic circuit 2 obtains the digital data from the analog input circuit 1 through a predetermined connecting means 3, performs a predetermined protective operation using this, and outputs a trip command through the output circuit 4 when the condition is satisfied. Here, the analog input circuit 1 generally has a large output characteristic with respect to an input, that is, an amplitude or phase error due to variations in the components forming the analog input circuit 1.

The digital protective relay device according to the prior art is provided with a correction value storage circuit 5 for obtaining a correction value by a predetermined calculation to correct it and storing the correction value, and an operation / calibration selection input circuit 6, According to the operation / calibration selection input,
During operation, the correction value of the correction value storage circuit 5 is used to correct the digital data to perform a predetermined protection operation, and at the time of calibration, the correction value is obtained by performing a predetermined operation on the digital data. It is configured to be stored in.

[0004]

If the device having the above configuration is in an operating state for the purpose of protecting the power system and should be replaced due to a defect in the analog input circuit, a substitute is manufactured and replaced. It is generally done.
Also, like a busbar protection relay device, in a protection relay device that takes in the current of the line connected to the busbar and performs protection calculation,
An analog input circuit is often added as the number of lines increases. During this period, it is necessary to stop the operation of the protection device, but it is required to keep the protection device in a stopped state as short as possible because of the importance of the protection target.

As described above, when replacing or adding an analog input circuit to a substitute, even if an analog input circuit is prepared in advance as a spare, it is installed in a substation or the like where a protection device is installed. After carrying in, it was necessary to re-calculate the calibration values, making quick replacement, addition, and restoration work difficult.

That is, a new analog input circuit is brought in,
After replacement or addition, connect a test device for applying a reference input to the analog input circuit for calibration and various measuring instruments corresponding to various inputs, and switch from the operating state to the calibration state by operating / calibrating selection input It was necessary to perform the calibration work of. Further, in this work completion state, since it is not an operating state but a calibration state, there is a big problem that if the switching input is leaked, the actual operation cannot be started.

The present invention has been made to solve the above-mentioned problems of the prior art, and facilitates quick replacement and restoration work in the unlikely event of a failure of the analog input circuit and reduces the average repair time (MTTR). It is an object of the present invention to provide a protective relay device suitable for short system protection, and to provide a highly reliable digital protective relay device that does not require switching between calibration and operation and therefore does not forget to switch.

[0008]

In order to achieve the above object, an analog input circuit of a digital protective relay device according to claim 1 of the present invention stores a correction value used for correction calculation of digital data. A value storage circuit is provided, and the arithmetic circuit corrects the input digital data by using the correction value stored in the correction value storage circuit, and performs a predetermined protection operation using these corrected digital data. Configured.

A digital protective relay device according to a second aspect of the present invention is the digital protective relay device according to the first aspect, wherein the correction value storage circuit is integrated with an analog input circuit, and the block is detachable from the digital protective relay device. did.

A digital protective relay device according to a third aspect of the present invention is the digital protective relay device according to the first aspect, wherein the correction value of the correction value storage circuit is analog before the analog input circuit is incorporated in the digital protective relay device. The value obtained from the result of the correction calculation of the input circuit is stored.

[0011]

In the digital protective relay device according to the first aspect of the present invention, the analog input circuit is provided with the correction value storage circuit for storing the correction value for correcting the digital data, and the correction value of the corresponding analog input circuit is preset. Is stored in the memory circuit,
The arithmetic circuit automatically reads the correction value from the correction value storage circuit, corrects the input digital data using the correction value, and uses the digital data obtained thereby to perform a predetermined protection operation. .

The digital protective relay device according to claim 2 of the present invention has a simple structure because the correction value storage circuit is integrated with the analog input circuit. Claim 3 of the present invention
In the digital protective relay device according to (1), since the correction value is a value obtained from the result of the correction calculation of the analog input circuit before the analog input circuit is incorporated, it is possible to obtain each correction value in advance. Work efficiency improves.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a digital protective relay device according to the present invention. In FIG. 1, the analog input circuit 1 is generally composed of a plurality of transformers 11, a filter circuit 12, a sample hold circuit 13, a multiplexer 14, and an analog / digital conversion circuit 15 as shown. Note that each of these means is collectively referred to as a data acquisition means. 16 is a correction value storage circuit.

The plurality of system electric quantities input to the analog input circuit 1 are level-converted by the corresponding transformers 11, respectively, and the filter circuit 12 removes unnecessary harmonics for the protection operation, and then the sample-hold circuit. At 13, sampling is performed at a predetermined time interval and held for a predetermined time. These multiple analog values are selectively switched by the multiplexer 14 at predetermined time intervals and output. This analog value is converted into digital data by the analog / digital conversion circuit 15. Further, the correction value storage circuit itself is a circuit in which the correction value obtained in a predetermined procedure is written in advance by means having a correction value calculation and writing function described later.

In FIG. 1, the arithmetic circuit 2 reads the digital data and the correction value through the connecting means 3, performs a correction operation described later as an example with the digital data and the correction value, and uses the resulting digital data. A predetermined protection calculation is performed, and if the result satisfies the operating condition, a trip command to the circuit breaker is output via the output circuit 4.

Next, the operation will be described. First, the process of obtaining the correction value of the analog input circuit and storing it in the correction value storage circuit provided on the analog input circuit will be described with reference to FIG. In FIG. 2, the same reference numerals as those in FIG. 1 have the same functions, and the description thereof will be omitted. Note that, for simplification of description, correction of an error in the amplitude of the analog input circuit will be described below. The correction value calculation circuit 20 performs the following well-known amplitude value calculation and correction value calculation on the digital data i _jm of the channel j from the analog input circuit.

[0017]

[Equation 1] Amplitude value calculation Here, i _jm and i _jm-n represent digital data sampled at times separated by a time corresponding to 90 degrees of the AC waveform.

[0018]

[Number 2] Correction value calculation K _j = X _AC / I _j where X _AC has no error in the analog input circuit 1, shows the effective value of the digital data to be obtained when it is assumed that applies a predetermined AC input . Therefore, the correction value K _j for the corresponding channel j can be obtained by applying an accurate actual input to a predetermined value and _obtaining the ratio of the effective value I _j and X _AC obtained by the amplitude value calculation.

When a plurality of channels are provided as shown in FIG. 1, the necessary channel correction value K can be obtained by performing the above-mentioned processing for each input channel for each channel.

Next, the correction value obtained by this calculation is stored in the correction value storage circuit 16 provided on the analog input circuit 1 to complete the correction value calculation and storage processing of the analog input circuit 1. Next, a correction calculation using the analog input circuit 1 for which the above-described processing is completed will be described.

In FIG. 1, the arithmetic circuit reads the digital data i _jm of the channel j from the analog input circuit 1 and performs the aforementioned amplitude value calculation to obtain the amplitude value I _j .
The correction value K _j is also read from the correction value storage circuit 16. Then, the following correction calculation is performed.

[0022]

## EQU3 ## Y _j = K _j × I _j where Y _j is the amplitude value of the analog input circuit 1 to be used for a predetermined protection operation in the future, and since the correction is made using the correction value K _j , the amplitude is It is digital data with no value error.

According to the above embodiment, the analog input circuit 1
A correction value storage circuit 16 for storing the correction value of the channel of this input circuit is mounted in the input circuit, the correction value of the analog input circuit 1 is obtained and stored in advance, and the operation / calibration selection input circuit 6 is unnecessary. Therefore, even if a conversion procedure is required due to a failure of the analog input circuit 1 during operation, no complicated calibration work is required prior to operation, and it can be replaced immediately, and a protective relay with a short average repair time is provided. It is possible to provide a device and also a highly reliable protective relay device that does not forget to switch from the calibration state to the operating state. The above is a case where there is one analog input circuit, but the present invention is not limited to this.

FIG. 3 shows another embodiment of the present invention. In FIG. 3, the analog input circuits 1-1 to 1-n have the same configuration and the same function as the analog input circuit 1 described in FIG. 1, and show that n units are used.

When a plurality of analog input circuits are used, a correction value is obtained for each analog input circuit and stored in the correction value storage circuit on each analog input circuit as in the case of the above embodiment. . In operation, digital data and a correction value may be read from each analog input circuit and each accurate amplitude value may be calculated. Needless to say, it is necessary to attach different addresses to the respective analog input circuits so that the digital data and the correction value correspond to each other. By doing so, a similar effect can be obtained even in a protective relay device using a plurality of analog input circuits.

Further, although the embodiment of the present invention using one arithmetic circuit has been described in the above embodiments, the present invention is not limited to this, and a plurality of arithmetic circuits and one or more analog input circuits are provided. It is clear that the same effect can be obtained even with the configuration in which and are connected.

Although the amplitude value calculation described above is a widely used amplitude value calculation method, other known amplitude value calculation methods may be used, but the description thereof is omitted because it is not the gist of the present invention. However, it is obvious that the same effect can be obtained by any method.

Further, in the correction value calculation operation, the error correction on the amplitude has been described. However, the present invention is not limited to this, and a well-known operation for obtaining a phase difference between a plurality of inputs is performed. Is stored in the memory circuit, and this correction value is used in the protection operation to obtain the same effect as the operation data having no phase error between the inputs.

[0029]

As described above, according to the present invention, a correction value storage circuit is provided in an analog input circuit to store a correction value used for correction calculation of digital data, and the input digital data is corrected by the correction. Since a predetermined protection calculation is performed after correction using the value, even if replacement is required due to a defective analog input circuit during operation, complicated calibration work prior to operation is unnecessary, and It is possible to provide a protective relay device that can be replaced immediately and has a short average repair time, and a highly reliable protective relay device that does not forget to switch from the calibration state to the operating state.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a protective relay device according to the present invention.

FIG. 2 is a configuration diagram illustrating a process of calculating a correction value according to the present invention.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 analog input circuit 2 arithmetic circuit 3 connection means 4 output circuit 11 transformer 12 filter circuit 13 sample hold circuit 14 multiplexer 15 analog / digital conversion circuit 16 correction value storage circuit

Claims (3)

[Claims] 1. An analog input circuit having data acquisition means for sampling analog electric quantity of a power system at predetermined time intervals and then digitally converting it to obtain digital data, and a predetermined protection operation using the digital data. In a digital protective relay device comprising an arithmetic circuit for performing and an output circuit for outputting an arithmetic result, the analog input circuit is provided with a correction value storage circuit for storing a correction value used for correction arithmetic of digital data, and The arithmetic circuit corrects the input digital data by using the correction value stored in the correction value storage circuit, and performs a predetermined protection operation using the corrected digital data. Relay device. 2. The digital protective relay device according to claim 1, wherein the correction value storage circuit is integrated with the analog input circuit to form a block that can be attached to and detached from the digital protective relay device. Digital protective relay device. 3. The digital protective relay device according to claim 1, wherein the correction value of the correction value storage circuit is corrected by the analog input circuit before the analog input circuit is incorporated in the digital protective relay device. A digital protective relay device characterized by storing a value obtained from a calculation result.