JPS6124897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital protective relay device that uses a computer to process digital information obtained from an electric power system and protects the system based on the results, particularly when setting a set value of Mori reactance characteristics. The present invention relates to a method for detecting errors.

As the accident detection set value, in a distance relay device, there is an impedance value that determines the accident detection distance and a time for temporal coordination of operations, and in an overcurrent relay device, there is a critical current value that starts the operation.

These values are written into a predetermined storage section of the computer by the operator operating a switch (digital switch) on which numerical values are printed or a key.
Then, the protection operation uses these written values as
Current written every sampling period. This is done using data from a voltage transformer.

A minicomputer or microcomputer is used as a calculation means for a digital protective relay device. The advantage of using a computer is that multiple protection functions can be processed by the same computer, and depending on the setting value setting method, various setting values can be arbitrarily written for the protective relay device. It has the advantage of being able to set a range of settings using the same hardware, but it has the disadvantage of having to set the settings manually because there is a high possibility of pressing the wrong key or switch. It is.

An object of the present invention is to provide a method for detecting errors in setting of an accident detection set value, particularly in the case of mori reactance characteristics, which takes advantage of the above-mentioned advantages of computer processing and compensates for the drawback that setting of the set value by an operator is likely to be erroneous.

Hereinafter, a case where the present invention is applied to a conventional example will be explained with reference to the drawings.

FIG. 1a shows the characteristics of a conventional protective relay device. This is a general operating characteristic of a distance relay device expressed in impedance coordinates (R-X coordinates) based on the fact that the impedance from the protective relay device installation point to the fault point is proportional to the distance of the power transmission line. be. Here, M is the Moh characteristic for determining the accident direction, and O ₁ and O ₂ are the reactance first stage and second stage characteristics for measuring the reactance, respectively.

Calculating each of these M, O ₁ , and O ₂ protection functions with the same computer means that all protection functions calculate the impedance of the power transmission line, etc., and the input data is the same, so the line voltage is calculated more than the phase voltage. It is convenient because calculations such as calculating the zero-phase current by calculating the sum of the phase currents, and calculating the reference vector by shifting the phase of the current are common to M, O ₁ and O ₂ , and the results obtained for each can be shared. It is.

The circuit shown in Fig. 1b has the functions shown in Fig. 1a, and has a motor output M and a reactance of the first stage.
The O ₁ output passes through the AND circuit 2 and reaches the OR circuit 3 after the set time of timer T ₁ has expired, and the mo output M and reactance second stage output O ₂ pass through the AND circuit 1 and reaches the OR circuit 3 after the set time of timer T ₂ has expired. Also, the motor output M alone reaches the OR circuit 3 after the set time of the timer _T3 , thus forming a time-limited distance relay device in which each signal becomes a trip signal from the OR circuit.

In this case, the set values of the functions M, O ₁ , O ₂ that detect the magnitude of impedance and the set values of the functions T ₁ , T ₂ , T ₃ that coordinate the operation output in time are determined by the operator according to the applied system. is given to the computer by

Now, for example, T ₁ is from 1 second to 3 seconds, T ₂ is 2
Assume that T ₃ has a settling range of 3 to 10 seconds. The settings of each timer must be in the relationship T ₁ < T ₂ < T ₃ based on the concept of time-limited distance relay system, so T ₁ = 1.5 seconds, T ₂ = 2.0
For example, when the operator decides to set T ₃ = 4.5 seconds and turns the dial to set the number of seconds on the timer, an error occurs and the result is T ₁ = 1.5 seconds, T ₂ = 4.5 seconds, T ₃ = 2.0.
In some cases, it may take seconds.

At this time, an error in the setting value setting can be detected by calculating and comparing using a computer whether the following equations are satisfied: T ₃ −T ₂ >0 (1) T ₂ −T ₁ >0 (2). In other words, the difference between the set values of T ₃ and T ₂ can be detected because equation (1) no longer holds true.

Also, keys that do not have setting functions such as dials and have numbers printed from a minimum of 1 second to a maximum of 10 seconds. When setting T ₁ , T ₂ , and T ₃ to 1.5 seconds, 2.0 seconds, and 4.5 seconds, respectively, using a computer equipped with a switch, etc., T ₁ = 15 seconds, T ₂ = 20 seconds, and T ₃ = 45 seconds. When set, since the minimum time limit T _L and maximum time limit T _M are determined for each timer, it is only necessary to check whether the operator set value T _S satisfies the following equation.

T _L ≦T _S ≦T _M (3) In this way, digit errors in each setting time can be prevented by checking whether the above equation holds true.

Where T ₁ should be set to 1.5 seconds, it should be set to T ₁ = 1.7 seconds.
Even if the present invention erroneously sets the time to 1.0 seconds, it cannot be detected, but such an error will not cause a fatal malfunction or malfunction of the protective relay device.

The above description has been made regarding the detection of an incorrect setting of the timer setting value, but this also applies to the detection of an incorrect setting of the impedance setting value.

For example, in Figure 1a, the impedances Z ₁ , Z ₂ ,
Since the relationship Z ₁ <Z ₂ <Z ₃ exists between Z ₃ , it is sufficient to detect by calculation whether or not the following equation holds between the set impedances.

Z ₃ −Z ₂ >0 (4) Z ₂ −Z ₁ >0 (5) Furthermore, a wrong digit in the set value or a set value that exceeds the range of the set value can be detected by performing the same procedure as in the case of the timer described above. In other words, as shown in Fig. 2, it can be assumed that the Moh characteristic has a set value only in the range of the maximum value Z _M and the minimum Z _L , so Z _L ≦operator setting value ≦ Z _M (6) By calculating and comparing whether or not the relationship holds, it is possible to detect a set value that falls within a predetermined limit.

As described above, in the present invention, in a protective relay device that protects a power system by calculating a digital value obtained from an AC analog value of the power system using a computer, the setting value of the Mohr reactance characteristic, that is, the Mohr characteristic and When setting each operating impedance value of the reactance characteristic and the operating time of each timer for coordination of operations, the set values are compared in size, and the operating impedance values and the operation of each timer are compared. Since there is a predetermined magnitude relationship between times, if the result of the comparison is different from the predetermined magnitude relationship, it is determined that there is an error in the setting, and the setting value can be reset to the correct setting value.

[Brief explanation of the drawing]

Figure 1a is a general operating characteristic diagram of a conventional distance relay device with mho characteristics and reactance characteristics.
Figure b is a logic circuit diagram with the characteristics of Figure 1 a,
The figure is a diagram of the setting range of the Moh characteristic. M...Moh characteristics, _O1 , _O2 ...Reactance characteristics, _T1 to _T3 ...Timer.

Claims (1)

[Claims] 1. In a protective relay device that protects the power system by calculating digital quantities obtained from AC analog quantities of the power system using a computer, when setting the setting value of the Mori reactance characteristic, the magnitude between the set values is A method for detecting setting value setting errors in a protective relay device, the method comprising: detecting a setting error in each setting value by comparing the values.