JP2686191B2 - Direction distance relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional distance relay device (hereinafter simply referred to as a relay) used for protecting transmission and distribution lines in a power system.

[0002]

2. Description of the Related Art An example of a conventional relay operation principle block diagram is shown in FIG. In FIG. 2, E is the voltage of the protected system, I is the current flowing in the system, TE is the voltage input transformer, TC is the current input transformer, and FFE and FC are the fundamental wave (commercial frequency of the power system, for example, 50 Hz). The filters for removing components other than the fundamental wave, ADE and ADC are analog-digital converters.

ZSET is a means for calculating a product ZI of the output of the current filter FC and the settling impedance Z, and M is a memory means, and a failure occurs for a predetermined time (for example, 120 ms) even if the input voltage E becomes zero due to a near-point failure. Means for storing the previous voltage, DZ is the following two voltage vectors V1,
The direction and distance calculation means calculates the direction and distance of the failure point by calculating the phase difference of V2, and calculates the direction and distance by the following method.

V1 = EM (EM is the output of the memory means M) V2 = ZI-E product V1 * V2 = V1 (t-T). V2 (t−T) + V1 (t) V2 (t) = V1 · V2 · COSθ Therefore, if the product V1 · V2 ≧ 0, then two vectors V1,
It is judged that the phase difference of V2 is θ ≦ ± 90 °, and the product with output V1 · V
If 2 ≦ 0, the phase difference θ ≧ 9 between the two vectors V1 and V2
Judge as 0 ° and determine no output. L is an overcurrent means that outputs when the current input I is above a predetermined value, and determines the operating current sensitivity of this relay. AN1 is an AND circuit.

The operation of the conventional relay thus configured will be described with reference to the power system diagram of FIG. 3 and the operation principle vector diagram of FIG. In FIG. 3, PA and PB are power supplies, TL is a protected transmission line, PD is a capacitor type voltage transformer, CT is a current transformer, RY is a relay, and F1, F2, F3, and F4 are failure points. In FIG. 4, E1, E2, E3 and E4 are input voltages E corresponding to the respective fault points F1, F2, F3 and F4.
1M, E2M, E3M, E4M are input voltages E1, E2,
It is a memory voltage processed by the memory means M from E3 and E4.

Failure point F1. In the case of front external failure V101 = E1M V201 = ZI-E1 The phase distance θ1> 90 ° and the direction distance calculating means DZ does not operate.

Failure point F2. In case of limit point failure V102 = E2M V202 = ZI-E2 Operation limit of direction distance calculation means DZ with phase difference θ2 = 90 ° AND circuit A under the condition that overcurrent means L is operating at this time
It is output from N1.

Failure point F3. In case of internal failure V103 = E3M V203 = ZI-E3 The direction distance calculation means DZ operates with the phase difference θ3 <90 ° At this time, the AND circuit A is operated under the condition that the overcurrent means L operates.
It is output from N1.

Failure point F4. In the case of a rear close point external failure (fault voltage E4≈0) V104 = E4M V204 = ZI−E4 Although the fault voltage E4≈0, the direction is calculated by the direction distance calculation means DZ because the memory means M holds it for a predetermined time. Discrimination is also possible. Direction difference calculation means DZ with phase difference θ4≈180 °> 90 °
Is not working

As is apparent from the above description, the characteristic of this relay is represented as a circular characteristic (Moh characteristic) having the impedance ZI as a diameter, and two voltage vectors V1 (V1 above).
01, V102, V103, V104), V2 (V above)
201, V202, V203, V204) phase difference θ <
Operates under the condition of ± 90 ° and output of overcurrent means L ,
Its and serves as a non-operating time not you. In order to make the fault detection sensitivity as high as possible, the setting of the overcurrent means L is, for example, 5% of the rated current, that is, the secondary rated current of CT is 5A.
In the case of, it is about 0.25A.

[0011]

FIG. 5 shows an example of the input waveform of each part at the time of an external failure at the failure point F4 rear near point. When the voltage of the system is obtained through the capacitor type voltage transformer PD (generally, the upper type transmission line generally uses the capacitor type voltage transformer PD.) It is very close to the transient phenomenon of the capacitor type voltage transformer PD. ED in FIG. 5 to failure position phase depending on the voltage input E immediately after the point failure
It is known that a DC component such as When the voltage input E or the current input I contains a frequency component other than the fundamental wave, that is, a DC component and a harmonic component, they are almost removed by the filters FE and FC and the digital filter provided in the direction distance calculation means DZ. It

However, it is difficult to completely remove a direct current component that decays in time (not a direct current that does not change at all) like the ED of FIG. 5, and the remaining direct current component EDF is a vector V2 = ZI. -Direction distance calculation means DZ as EDF
If the input is input to the conventional relay, the directional distance calculating means DZ for calculating the fundamental wave component cannot perform the direction determination despite the external failure at the rear close point (fault point F4), and the relay operates unnecessarily. There was a flaw.

The present invention has been made to solve the above problems, and provides a highly reliable directional distance relay device which does not perform unnecessary operation even when a direct current component other than the fundamental wave is included due to an external failure at the rear closest point. The purpose is to provide.

[0014]

SUMMARY OF THE INVENTION A directional distance relay device according to the present invention is a voltage input transformer for introducing a voltage of a power system, a current input transformer for introducing a current of the power system, and the introduced current input. And a settling impedance, a calculation means for calculating a product of the input voltage and the directional distance calculation means for calculating a direction and a distance to the failure point using the calculated product value, and an output signal from the directional distance calculation means. A certain time
Delay means for delaying and outputting, and outputting an output signal when it is detected that the calculated product value is a predetermined value or more
A voltage detection means, the output from the direction distance calculating means
When inputting a signal, input the output signal from the voltage detection means
Then, the output signal from the direction distance calculation means is delayed by the delay
AND gate circuit for immediate output without passing through the means, and when the output signal is input from the voltage detecting means,
The output from the delay means or the
The output from the AND gate circuit is used as the device output.
And an OR gate circuit for outputting the output .

[0015]

According to the present invention, when the product value is equal to or less than the predetermined value due to the influence of the DC voltage component mixed in the input voltage introduced from the power system, the output from the direction distance calculating means is included in the output. Since the direct current component is output to the outside through the delay means that is set to the same time as the attenuation, the mixed direct current component does not cause a trouble in the direction determination of the accident point.

[0016]

First, before explaining the operation of the present invention, the outline of the present invention will be described. As apparent from FIG. 5, the input voltage E is compared with the product ZI of the current input I and the settling impedance Z. The larger the included DC component ED, the E of the DC component
The influence of D is large and the possibility of malfunction increases.

That is, assuming that the DC component ED is fixed, a problem occurs when the product ZI is small. The present invention focuses on this point, and only when the product ZI is less than or equal to a predetermined value,
This is to delay the relay operation time to the minimum necessary until the DC component ED is attenuated to a level that does not cause a problem.

The operation of the present invention will be described below with reference to FIG. In Figure, H is the product ZI current input I and settling impedance Z maximum value of, for example, a DC component ED to that electrostatic pressure detecting means outputs when the predetermined value or more in the case of 2V to set to approximately 4V. T is a delay means for the case where the product ZI is smaller than a predetermined value, and is set to a time longer than the decay time of the direct current component ED, for example, 60 ms. With both outputs of the element DZ, the delay means T is bypassed and output through the OR circuit OR1. That is, the product ZI is 4V
For the above failures, the output of the direction distance calculation element DZ is delayed by the delay means T.
Output directly without passing.

Here, the idea of setting the voltage detecting means H to about 4V when the maximum value of the DC component ED is 2V is as follows.
When the input DC component ED of the filter FE is 2V, the DC component after passing through the digital filter provided in the filter FE and the direction distance calculating means DZ is considerably attenuated, for example, 1
/ 10, that is, if the product ZI is 4 V or more at EDF = 0.2 V and EDF = 0.2 V << ZI = 4 V , the influence on the direction determination of the direction distance calculation means DZ can be ignored.

In the relay thus constructed,
Be included DC component to at voltage input rearward closest point outside the failure other than the fundamental wave, it is not to be unnecessary operation without Kanse to the size of the product ZI. Further, in the case of ZI ≧ 4V due to an internal failure in the front direction, the above-mentioned delay means T is irrelevant, so the direction distance calculation means DZ
The relay operates at a high speed (for example, 30 ms) only for the original operation time of.

Further, in the case of ZI≤4V due to the internal front failure: In the case of ZI≤4V, the delay means T = 60 ms is connected to the output of the direction distance calculation means DZ regardless of the forward or backward failure. The operation time is delayed by 60 ms (30 ms + 60 ms = 90 ms as a whole). However, since a fault current of ZI ≦ 4V has a small fault current as shown below (fault current below the rated current as shown below), this kind of operation time delay is important for preventing damage to equipment in the power system and ensuring system stability. It can be said that there is no problem at all.

Relation between settling impedance Z and input current I when ZI = 4V (CT secondary current 5) Z ohm 1 2 4 8 16 IA 4 2 1 0.5 0.25

In the above description, the present invention is applied to a directional distance relay having a circular characteristic (Moh characteristic), but it is also effective for a relay having another characteristic, such as a rectangular characteristic directional distance relay. Needless to say.

[0024]

As described above, according to the present invention, the operation time is slightly delayed only when the product of the settling impedance and the input current is less than a predetermined value, without sacrificing other characteristics. Even if a direct current component other than the fundamental wave is input as the voltage input from the capacitor-type transformer PD due to an external failure at the rear near point, there is an effect that a highly reliable directional distance relay device that does not perform unnecessary operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an operation principle showing an embodiment of the present invention.

FIG. 2 is a block diagram of an operation principle showing a conventional relay (directional distance relay device).

FIG. 3 is a power system diagram to which a relay (direction distance relay device) is applied.

FIG. 4 is a vector diagram of an operating principle of a relay (direction distance relay device).

FIG. 5 is a waveform diagram showing an input waveform example of each unit when a failure at a failure point F4 occurs.

[Explanation of symbols]

 E Voltage of protected system I Current of protected system TE Voltage input transformer TC Current input transformer ZSET Means for calculating ZI M Means for calculating memory DZ direction distance calculating means H Voltage detecting means T Delay means RY Relay direction Distance relay apparatus

Claims (1)

(57) [Claims] 1. A voltage input transformer for introducing a voltage of a power system, a current input transformer for introducing a current of the power system, a calculating means for calculating a product of the introduced current input and a settling impedance, and the input voltage. constant time and direction distance calculating means for calculating the direction and distance to the fault point, the output signal from the direction distance calculating means using been product value calculation and
And a delay means for delaying the output and outputting an output signal when it is detected that the calculated product value is equal to or more than a predetermined value.
A voltage detecting means for force out from the direction distance calculating means
When inputting the input signal, input the output signal from the above voltage detection means.
When the force is applied, the output signal from the direction distance calculation means is delayed.
AND gate that outputs immediately without going through the delay means
Output from the circuit and the delay means, or the voltage detection
Before inputting the output signal from the output means, before the delay means
The output from the AND gate circuit is referred to as the device output.
And an OR gate circuit that outputs the directional distance relay device.