JP2997609B2 - Digital protection relay with automatic adjustment function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a digital protective relay having an automatic adjusting function for automatically adjusting the position phase of the analog input signal in the digital protective relay for protecting a power system.

[0002]

2. Description of the Related Art FIG. 9 shows the basic configuration of an arithmetic digital relay described in Vol. 41, No. 4, published by Electric Joint Research (published by the Electric Joint Research Society). In the figure, 1 is an auxiliary transformer that insulates system voltage and current, converts the size and takes in the size,
2 'is a filter circuit for removing high-frequency components of the input, 3 is a sample-and-hold circuit (S / H) for holding the voltages of a plurality of input signals at the same time, and 4 is a circuit for switching a plurality of input signals to select one. Multiplexers (MPX) and 5 are A / D converters (A / D) for converting an analog signal output from the multiplexer 4 into a digital signal.

Reference numeral 6 denotes a buffer for storing A / D-converted data, and reference numeral 7 denotes a buffer which is controlled by controlling a sample-and-hold circuit 3, a multiplexer 4, an A / D converter 5, and a buffer 6 separately from a CPU described later. A / D input signal for each electrical angle
A control circuit 8 for converting is a clock signal generation circuit (CLK) for generating a clock signal.

[0004] 9 'is a CPU for performing digital processing, 10'
Is a ROM storing programs and fixed data, 11
Is a RAM for storing variable data, 12 is a setting circuit for setting from outside, 13 is an interface circuit for outputting a judgment result of a relay element, and 14 is an auxiliary relay for output.

Next, the operation will be described. The voltage and current of the system pass through the auxiliary transformer 1 and the filter circuit 2 ', and are sampled and held by the sample and hold circuit 3 at a cycle of a constant electrical angle. One of a plurality of input signals is selected by the multiplexer 4, converted into a digital signal by the A / D converter 5, and stored in the buffer 6.

FIG. 10 is a block diagram showing the processing contents of the CPU 9 ' . The data stored in the buffer 6 is read by the data input circuit 50, filtered by the digital filter 51, and necessary for relay processing such as an effective value. The calculation is performed by the execution value calculation circuit 53, and is compared with the set value calculated by the set value calculation circuit 54. The relay element determination circuit 55 performs a determination process to determine whether an overcurrent flows. judge.

Here, in the auxiliary transformer 1 and the filter 2 ', there is actually an error in the characteristics of the components.
The magnitude and phase of the input signal of the signal supplied to the / D converter 5 change. Since the CPU 9 'does not know in advance how much an error is in each circuit, the CPU 9' processes it as if there is no error, and corrects it.

To perform this correction, as shown in FIG.
Normally, filter circuit 2 'is connected to capacitors C1 and C2,
The fixed resistors are variable resistors VR1 and VR2, and the differential amplifier U
And the magnitude and phase of the signal are adjusted to the original values by the variable resistors VR1 and VR2. The adjustment is to supply a predetermined input and change the value of the variable resistor so that the output voltage value and the phase of the corresponding filter become the design values.

[0009]

However, such a conventional method always requires adjustment before testing a product, and it measures two values of the input side size and the output side size. There is a problem that the possibility of human error is high and it takes time because the adjuster turns and adjusts the variable resistors one by one.

The present invention has been made in view of such a situation, and is intended to easily perform adjustment, reduce human error, and shorten the adjustment time.

[0011]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention provides two auxiliary systems with a predetermined phase difference.
Two predetermined inputs applied to the transformer
Sampling and A / D conversion of each force signal and import
And calculate the phase difference between these two input signals,
The calculated phase difference is applied to the two auxiliary transformers.
Sample and hold tie based on the phase difference of the
Calculate the time to control the timing, and use this time as the correction value.
The correction value is stored in a correction value storage circuit, and a sample is stored based on the correction value.
Controls sample hold timing of pull-hold circuit
It is provided with a control circuit that performs

[0012]

[Operation] At the time of adjustment, two predetermined input signals are set in advance.
Apply to each of two auxiliary transformers with the determined phase difference
Sampling, A / D conversion, and the two input signals
The phase difference between the two shows the relationship between two phases, such as power calculation.
Is calculated in formula, the two complement this calculated phase difference
Based on the phase difference of the signal applied to the auxiliary transformer.
The time to control the pull hold timing is required,
This time is stored as a correction value. During operation, it is memorized
Sample and hold circuit
The pull hold timing is controlled. Therefore, the key
The adjuster supplies a predetermined input to the CPU to compensate.
Adjustment can be performed simply by issuing a command to perform a positive operation.
Can be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
The same parts as those of the conventional apparatus use the same symbols. FIG. 1 shows the present invention.
FIG. 3 is a block diagram showing a first-stage technology 1 of FIG.
The circuit 2 does not use a variable resistor as shown in FIG.
The constant resistors R1 and R2 are used. FIG.
56 is a block diagram showing the processing of FIG.
Is a correction value calculation circuit.

Next, the operation will be described with reference to FIG.
You. First, in the adjustment stage before operation as a protective relay
Then, the correction value is calculated. CPU in control circuit 7
Set to inform that adjustment will be performed by 9 and decide in advance
Input, that is, an input with a known value
Force is input to the auxiliary transformer 1 of FIG. As a result, FIG.
Is turned on, and the calculation of the correction value starts.

An input signal is taken into a data input circuit 50.
And is filtered by a digital filter 51 to obtain an effective value.
And this value is defined as the effective value calculation result. this
The value of the signal can be calculated at design time.
The measured value is defined as the theoretical value.

For this theoretical value, a predetermined input
The value obtained when supplying
Find the value divided by the effective value calculation result, and use this value as the correction value.
You. In other words, this value is used for the entire input circuit,
1, filter 2, sample and hold circuit 3, multi
The error of the circuit including the plexer 4 and the A / D converter 5
You. This correction value is stored by a predetermined operation.
Do with the operation to all of the input circuit.

After that, the control circuit 7 is operated and the CPU 9 is operated.
By stopping the setting of the adjustment by the switch of FIG.
Since S1 turns off, it will be operated as a protective relay
Swell. For this reason, the actual load
A value corresponding to the circuit is calculated.

The operation calculated by the effective value calculation circuit 53
The value is multiplied by the correction value previously obtained by the correction value calculation circuit 57.
The correction process is performed by the correction circuit 56 to determine the relay element.
In the circuit 55, the signal is supplied from the set value calculation circuit 54.
Comparison between the output from the correction circuit 56 and the
Performs elementary processing and determines whether overcurrent has flowed
I do.

In the correction process, the stored correction value is input.
Is multiplied by the effective value calculation result of
The generated error is corrected and converted into a theoretical value.
In other words, the input value to be compared and the set value match the same theoretical value.
The adjustment was completed by having it adjusted.

In the preceding technology 1, the correction value is set to the effective value of the input.
The calculation result was multiplied.
The same can be achieved by dividing by. Entering
The effective value of the force is calculated based on the calculation execution cycle of the relay (electrical angle 30 degrees)
Must be executed every time
No, but the set value does not change every time.
It does not have to be executed several times.

By performing processing on the set values,
Is reduced, which is advantageous in the processing time of the CPU 9.
The configuration of the circuit is the same as that of FIG.
The processing circuit is as shown in FIG.

Next, the operation of the preceding technology 2 will be described with reference to FIG.
Will be described. First, the tone of before to operate as a protection relay
In the adjustment stage, a correction value is calculated. This content is
This is the same as in the first embodiment. Then, it is stored in the buffer 6 of FIG.
The read data is read by the data input circuit 50 of FIG.
After filtering by the digital filter 51
Then, relay processing such as an effective value in the effective value calculation circuit 53 is performed.
Perform the necessary calculations.

Next, the correction value calculating circuit 57
Divides the set value of the set value calculation circuit 54 by the calculated correction value
Is performed by the correction circuit 56, and the set value
And the calculation result of the effective value of the input by the relay element determination circuit 55
In comparison, processing as a relay element is performed, and an overcurrent
Determine whether the

In the correction process, the stored correction value is used as a theoretical value.
Generated for each input circuit by dividing a certain set value
The theoretical value is converted according to the error. That is,
The input value to be compared with the set value is a value that includes the error of each input
By adjusting to, the adjustment was completed.

The first- stage techniques 1 and 2 relate to the adjustment of the input size.
However, two inputs, such as system voltage and current, are
The two phase relations are important in the relay element handled
Therefore, it is necessary to adjust the phase. According to the method shown below
The advantage of being able to adjust the phase
There is.

FIG . 6 shows a digital protection relay according to the present invention.
FIG. 2 is a block diagram showing one embodiment (Embodiment 1). Same figure
, 15 is an A / D conversion system that can be controlled by the CPU 9
The control circuit and the sample hold circuit 3a are controlled for each input.
It is made possible.

FIG. 5 shows the operation of the CPU 9 of the apparatus shown in FIG.
It will be described based on the following. In FIG. 5, 58 is a sample hose.
Timing hardware control circuit, 60 is power calculation
The circuit 61 is a relay operation circuit.

First, an adjustment stage before operation as a protection relay
At the floor, a correction value is calculated. CPU as described above
Set to inform that adjustment will be performed by 9 and decide in advance
Two input signals with a predetermined phase
You. This turns on the switch S1 in FIG.
Start the operation.

The correction values referred to here are two predetermined values.
Calculation that understands two phase relations like input power
Calculate the phase difference using the formula,
To determine if it is late or late
This is the time for controlling the hold timing. One
Delays the sample and hold process if the phase is advanced.
Sample delay if the phase is late
So that the two phase relationships are the same.
You.

The sample hold time shifted at this time
Is stored by a predetermined operation, and this is stored in all inputs.
About it. Thereafter, the adjustment setting by the CPU 9 is stopped.
Therefore, switch S1 in FIG. 5 is turned off, and as a protective relay,
operate.

The data stored in the buffer 6 is stored in the same manner as in the prior art.
The input data is read by the data input circuit 50, and
After filtering by the filter 51, the relay operation circuit 61
Performs calculations required for relay processing, such as the effective value,
The element judgment circuit 55 compares this with the set value, for example.
Performs processing as a lay element and checks if an overcurrent flows.
judge. In this method, the position is
Since the phases are matched, calculations can be performed with instantaneous values like a differential relay.
It can be used without any problem.

In the first embodiment, the phase adjustment is performed as shown in FIG.
Has been described using the / D conversion control circuit 15.
However, those who do not use the A / D conversion control circuit as Reference Example 1
Explain the law. In other words, no special circuit is required,
There is an advantage that the control of is unnecessary. Accordingly
The circuit configuration is as shown in FIG.
It is assumed that no variable resistor is used as shown in FIG.

FIG. 7 is a diagram for explaining the operation of the CPU in this case.
Before operating as a protective relay first
In the adjustment stage, a correction value is calculated. CPU 9
To notify that adjustment will be performed by
Two certain inputs are applied with a predetermined phase.

As a result, the switch S1 shown in FIG.
To start calculating the correction value. Here, the correction is predetermined
A certain two inputs are separated into two phase relationships such as power calculation.
Calculate with one of the above formulas.
To determine if it is running or late
Is to calculate the angle.

That is, if the phase is advanced, the phase shift angle
And if the phase is late, advance the phase shift angle,
That is, the two phase relationships are the same. This
At the time of the phase shift is stored by a predetermined operation,
This is performed for all inputs. Thereafter, the CPU 9
Stop the adjustment setting and turn off the switch S1 in FIG.
Operate as a protective relay.

Then, the data is stored in the buffer as in the prior art.
After reading the data,
Performs the calculations required for relay processing, such as values, and
Process as a relay element by comparing
It is determined whether a current has flowed.

In the correction process, the input is shifted based on the stored correction value.
By performing the phase calculation, the error generated for each input circuit can be calculated.
It is corrected and converted to a theoretical value. In other words, compare
Input value and set value to the same theoretical value.
This means that the adjustment was completed. Even in this method, the instantaneous value
Phase, so instantaneous values can be measured like a differential relay.
Anything that performs calculations can be used without any problems.

In the first embodiment and the first embodiment, the phase adjustment is input.
Explained that performed on it, a set point as ginseng Reference Example 2
A method to be performed for will be described. When done on input
Calculation execution cycle (predetermined as electrical angle 30 degrees)
Must be executed each time, but the set value is
It doesn't change every time, so you don't have to execute every time
No. By performing processing on the set value, the number of processing
This is advantageous in the processing time of the CPU.

Next, the operation will be described with reference to FIG.
You. First, in the adjustment stage before operation as a protective relay
Then, a correction value is calculated. This content is the same as in Reference Example 1.
It is like. And it was stored in the buffer as before.
After reading the data and performing digital filtering, the effective value
Perform calculations required for relay processing.

Next, the correction value determined in advance is added to settle.
Perform the correction process of calculating the value, and
Processing as a relay element by comparing with the calculation result
To determine whether an overcurrent has flowed. Correction process
By adding the stored correction value and calculating the set value,
And converts the theoretical value according to the error generated for each input circuit
It does. In other words, the input value to be compared and the set value
Is adjusted to match the value of each input including the error
Is done. This method is like determining the direction
Can only be used with relay elements.

[0041]

As described above, according to the present invention, the adjustment itself is performed.
Is because the CPU automatically performs it, causing a human error.
It is difficult to adjust and can be adjusted in a short time. In addition,
Errors in all input circuits, not just lance and filter circuits
Can be corrected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first-stage technique 1 .

FIG. 2 is a diagram showing an internal configuration of the filter circuit of FIG.

FIG. 3 is a block diagram for explaining an operation of a CPU in the first technology .

FIG. 4 is a block diagram for explaining an operation of a CPU in the first technology .

FIG. 5 shows a CP in one embodiment (Example 1) of the present invention .
It is a block diagram for explaining operation of U.

FIG. 6 is a block diagram illustrating a configuration of the first embodiment .

FIG. 7 is a block diagram illustrating an operation of a CPU according to a reference example 1 .

FIG. 8 is a block diagram illustrating an operation of a CPU according to a reference example 2 .

FIG. 9 is a block diagram showing a configuration of a conventional example.

FIG. 10 is a block diagram for explaining the operation of the CPU in FIG. 9;

11 is a diagram showing an internal configuration of a filter used in FIG.

[Description of Signs] 1. Input transformer, 2. Filter, 3. Sample hole
Circuit, 4 ... multiplexer, 5 ... A / D conversion circuit, 6
... buffer, 7 ... control circuit, 9 ... CPU, 53 ... effective value
Calculation circuit, 54 Setting value calculation circuit, 55 ... Relay element size
Constant circuit, 56 correction circuit, 57 correction value calculation circuit, 58
… Sample and hold timing hardware control circuit,
60 ... power calculation circuit, 61 ... relay operation circuit.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-22833 (JP, A) JP-A-61-285021 (JP, A)

Claims (1)

(57) [Claims] An analog signal obtained from a system via an auxiliary transformer is sampled at a constant electrical angle and A / D
A digital protection relay having an automatic adjustment function for automatically adjusting a digital protection relay that protects a system based on a result of performing a digital operation after conversion and comparing and judging with a set value . Each to auxiliary transformer
Each of two predetermined input signals to be applied is supported.
Sampled, A / D converted and imported, and this imported
Calculate the phase difference between two input signals and calculate the calculated phase difference
And the phase difference between the signals applied to the two auxiliary transformers and
Control the sample and hold timing based on the
Between the two, and record this time as a correction value in the correction value storage circuit.
The sample and hold circuit based on the correction value
A digital protection relay having an automatic adjustment function, comprising a control circuit for controlling a sample hold timing .