JPH06292321A - Method of setting operating range of digital distance reray - Google Patents

Abstract

(57) [Abstract] [Purpose] The optimum rear element R is the input element set values of only the front element X _F , load angle θ _S , and line angle θ _L.
Providing a digital type distance relay with a function to calculate the value of _b . [Structure] A set value input unit is provided in the distance element, and each value of the front element X _F , the load angle θ _S , and the line angle θ _L is input from the set value input unit, and the calculation processing unit uses the above respective values. The value of the rear element _Rb is calculated within a range not exceeding the predetermined maximum value of the rear element, and the operation area of the distance relay, that is, the quadrilateral characteristic of the distance relay is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance relay used, for example, for protection of a power transmission line among devices intended to protect electric power systems and equipment, and more particularly to a digital type distance relay using a microcomputer. .

[0002]

2. Description of the Related Art First, a distance relay installed as shown in FIG. 3 for protecting a protection target such as a power transmission line will be described.
In FIG. 3, 1 is a current transformer, 2 is a transformer, 3 is a distance relay, 4 is a power transmission line, and 5 is a circuit breaker. The distance relay 3 operates the circuit breaker 5 based on the outputs from the current transformer 1 and the transformer 2 to protect the power transmission line 4 in the protection section from a short circuit or a ground fault.

An internal block diagram of the distance relay 3 is shown in FIG.
Shown in. 4, 6 and 7 are input transformers,
8 and 9 are phase shift circuits, 10 is an arithmetic processing unit, and 11 is a set value input.
It is a force. Detected by current transformer 1 and transformer 2
Current I and voltage V are applied to the input transformer 6 and the input transformer 7.
More suitable level I_T, V_TIs converted to the input amount of. Entering
Competence I_T, V_TAre guided to the phase shift circuits 8 and 9, respectively, and
Vector composition processing to realize the quadrilateral characteristic described
(Phase shift processing) is performed. By performing phase shift processing
Input amount I_T, V_TAngle θ_L, Θ_SThe characteristics of
Given. θ_LIs the impedance angle t of the transmission line
an^-1(L / R), and the line angle θ _LCall
And θ_SIs a load area existing in the transmission line
The angle is set so that 0 does not work, and load it below.
Angle θ_sCall.

Further, the arithmetic processing section 10 has a quadrilateral operation characteristic as shown in FIG. In FIG. 5, R _F and X _F are front elements set based on the length of the line to be protected of the distance relay, and R _b and X _b are distances even when the voltage becomes extremely small due to a near end failure or the like. It is a rear element provided so that the relay can operate reliably, and in particular, the R _b element has a characteristic that the load angle θ _s is inclined so that the relay does not operate unnecessarily due to the exciting inrush current generated by the load. There is.

In the arithmetic processing unit 10, the quadrilateral operation area is determined by the impedance Z monitored by the distance relay 3, that is, the input quantities I _T and V _T, and the impedance Z represented by the equation (1) is the quadrilateral. Determine if it is within the motion area of the shape.

[0006]

[Equation 1]

When the impedance Z is within the quadrilateral operation area, it is determined that an internal accident has occurred and a trip command is output to the circuit breaker 5.

[0008]

However, the conventional
The phase shift circuit is used as an active element for resistors, reactors and capacitors.
Because it is composed of
Road angle θ_LAnd load angle θ _SOnce you have set
It is very difficult to change the set value, and the adjustment range of the phase shift angle is also
There were issues such as being limited.

Therefore, when the impedance angle of the line changes depending on the material of the transmission line or when the load angle is changed depending on the type of load, the line angle θ is set in advance.
_When preparing several combinations of _L and load angle θ _S and changing the values of line angle θ _L and load angle θ _s , select an appropriate one from the above combinations and replace the distance relay itself. I was using it.

If it is necessary to set θ _S <θ _L depending on the conditions, the straight line of the rear element R _b may be a straight line having an angle θ _L from the origin depending on the setting of the front element X _F as shown in FIG. Cross at point A. This is due to a failure (far end failure) at a larger impedance point with point A as the boundary,
Impedance seen by the long-distance relay at the time of failure (eg Z
_P ) is outside the operating range. In other words, the distance relay will not operate despite the internal failure. On the other hand, conventionally, the above-mentioned inconvenience has been solved by changing the rear element R _b to the rear element R _b ′.
There is a problem in that the value of the rear element R _b needs to be variable, the settling items naturally increase, and numerical processing is required to calculate the value of the rear element R _b ′ to be input, which complicates the processing. is there.

The present invention has been made in view of the above-mentioned problems of the prior art, and is optimal for the set values by the input set values of the front element X _F , the load angle θ _S , and the line angle θ _L. An object of the present invention is to provide a digital distance relay having a function of calculating the value of the rear element R _b .

[0012]

In order to achieve the above object, in the first aspect of the invention, a set value input section is provided in the arithmetic processing section, and the element X _F in front of the set value input section and the load angle θ _S. , Each value of the line angle θ _L is input, and the value of the rear element R _b is calculated in the arithmetic processing unit using each value. Further, in the second invention, it is confirmed whether or not the value of the rear element R _b calculated by the arithmetic processing unit exceeds the predetermined maximum value of the rear element.

[0013]

In the first aspect of the invention, the distance relay is calculated by calculating the value of the rear element R _b from the values of the front element X _F , the load angle θ _S , and the line angle θ _L input to the set value input section. , The quadrilateral characteristic of the distance relay is set. In the second invention, when the rear element _Rb derived by the first invention exceeds a predetermined maximum value of the rear element, the rear element _Rb may exceed an operational allowable range. Displayed outside.

[0014]

The contents of the present invention will be described in detail with reference to the drawings. The front element X _F and the load angle θ are set in the set value input unit 11 of FIG.
The respective values of _S and the line angle θ _L are input, and the arithmetic processing unit 10 calculates the rear element R _{b in the} procedure shown in FIG. FIG. 1 is a flow chart for explaining the procedure for calculating the value of the rear element R _b for obtaining the optimum operation region according to the first invention.

That is, in step S2 of FIG. 1, the value of R _M of FIG. 2 is first obtained by using the equation (2).

[0016]

[Equation 2]

Here, Z _{1 in the} equation (2) is represented by the equation (3).

[0018]

[Equation 3]

Next, in step S3, the R _F 'value of FIG. 2 is obtained using the equation (4).

[0020]

[Equation 4]

Here, Z _{2 in the} equation (4) is represented by the equation (5).

[0022]

[Equation 5]

Next, in step S4, the above equations (2) and (4) are substituted into the following equation (6) to obtain R _b . However, K is a margin with a margin of error.

[0024]

[Equation 6]

The quadrilateral characteristics shown in FIG. 2 are set by the respective values of the front element X _F , the load angle θ _S , the line angle θ _L , and the rear element R _b obtained by the equation (6). However, since R _b obtained by the equation (6) is a value arbitrarily set by the values of X _F , θ _S , and θ _L input to the set value input unit, it is large enough to cause an operational problem. May take a value.

Therefore, in the second aspect of the present invention, the value of the rear element R _b that is allowed in operation, that is, R _bM is set in advance and compared with the rear element R _b obtained by the equation (6).
That is, in step S5 of FIG. 1, when the result of comparing the rear element R _b obtained by the equation (6) and a predetermined R _bM is R _b > R _bM , in step S7, the ( It is displayed on the outside that the rear element _Rb calculated by the equation (6) exceeds the operationally allowable range.

Further, in step S8, a process for re-inputting and setting the front element X _F , the load angle θ _S , and the line angle θ _L is performed. Then, the above-described operations from step S1 to step S5 are _repeated, and when R _b > R _bM , the quadrilateral characteristic shown in FIG. 2 is set in step S6. It should be noted that the calculation processing for obtaining the rear element R _{b according} to the flowchart shown in FIG. 1 is performed by utilizing the idle time such as the normal relay calculation processing, so that the relay function is not hindered and a new hardware is added. There is no need to add additional clothing.

[0028]

According to the present invention, the respective values of the front element X _F , the load angle θ _S , and the line angle θ _L are input from the constant value input unit, and only the respective values are used, and the rear element R _b of the arithmetic processing unit is used. By calculating a value and confirming that the value of the rear element _Rb does not exceed a predetermined maximum value of the rear element, the operation area of the distance relay, that is, the quadrilateral characteristic of the distance relay is set.

Therefore, the optimum quadrilateral characteristic with respect to the set input value can be automatically set without requiring complicated processing. Further, even if the rear element obtained by the calculation exceeds the operationally permissible range, it is possible to set an appropriate quadrilateral characteristic by re-setting the input value. Moreover, since it is not necessary to prepare a plurality of distance relays, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart for determining a rear element according to the present invention.

FIG. 2 is a diagram showing a quadrilateral characteristic of a distance relay determined by using a rear element calculated according to the present invention.

FIG. 3 is a diagram showing a connection configuration of a distance relay.

[Figure 4] Internal block diagram of the distance relay

FIG. 5 is a diagram showing a quadrilateral characteristic of a conventional distance relay.

FIG. 6 is a diagram showing a quadrilateral characteristic of a conventional distance relay.

[Explanation of symbols]

 1 Current Transformer 2 Transformer 3 Distance Relay 4 Transmission Line 5 Circuit Breaker 6,7 Input Transformer 8,9 Phase Shift Circuit 10 Arithmetic Processing Section 11 Set Value Input Section

Claims (2)

[Claims] 1. A method of setting an operation area of a digital distance relay having an operation area of a quadrilateral characteristic, wherein a front element calculated based on a line length to be protected, an impedance angle of a transmission line, and an existence inside the transmission line. A load angle set to an angle so that the distance element does not operate in the load region, and a rear element is calculated using the rear element, and the quadrilateral characteristic is determined by the rear element. Operating area setting method. 2. The digital distance relay according to claim 1, wherein said rear element is compared with a predetermined value, and when said rear element exceeds a predetermined value as a result of said comparison, said rear element After outputting to the outside that the rear element exceeds a predetermined value, the front element, the impedance angle, and the load angle are input again, and the operation range setting of the digital distance relay is performed. Method.