JPS6277018A - Variable width overcurrent relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a variable width overcurrent relay, and more particularly to a variable width overcurrent relay suitable for use as a stopper of a distance relay type overcurrent relay. [Background of the invention] 1i! As a current change character IA relay, special khi 1975]-
The system described in Publication No. 1:1197 is known, and does not operate with the steady load current of the grid, and if some kind of fault occurs in the grid and there is a change in the phase or absolute value of the current, the preset Detect a current change that exceeds the value! l!
He is set to make 11 works. A conventional V41+"f of this type is explained based on FIGS. 5 and 6. In FIG. 5, 1 is a signal conversion circuit; 3 is a band-pass filter circuit; 3 is a memory filter circuit; 4 is an addition circuit;
5 is a phase-increasing rectifier circuit, 6 is a low-pass filter circuit, 7 is a subtraction circuit, and 8 is a level detection circuit. 9 is an OR circuit, 10 is a time-limited operation timer, 11 is an output circuit, 15 is a change width detection element, and 16 is an overcurrent element. Load '+11 current information r obtained from the grid transmission line
FIG. 6 shows a block diagram of the principle of the change range detection element 15 in the case of detecting four changes in current at the time of a fault in the system. The operating principle of the variation width detection element 15 is that only the fundamental wave component is extracted by the bandpass filter 2, and then the variation width detection element 1
5 and '6iJε elements 16, and the signals of the change width detection element 15 that do not pass through the memory filter circuit 3 follow the instantaneous current waveform and generate a signal according to the following equation (1). Kl (I^+∆engineering) ... (1)
K1: IV conversion ratio ■^: Current value before change Δ■: Changed current value On the other hand, the current of the vector storage circuit through the memory filter circuit 3 generates a signal according to the following equation (2). K21^ ・ (2) KI: Vector I-V conversion ratio Due to this memorization effect, the output signal of the adder circuit 4 for the change in Δt is the next (
3) It can be extracted as shown in the formula. K1ΔI+ (KI KI)T^...(3)
In the above equation (3), 1-2 is Ks2-2 at the rated current.
Adjust as follows. However, in reality, 1 does not always equal 2 due to causes such as current distortion, so (KI KI) I^ is mixed as an error component with the variation component as shown in equation (3). Since this error η"1 occurs as a constant value for the constant value, it is phase-increased and rectified to an absolute value, stored in two CR low-pass filters with different time constants, and then added to the subtraction circuit. Detect the change shown in the following equation (4) at IKIΔI+ (KI KI) I^11 (2 to Kl-
) I^l > I T... (4) ■T: Change detection value This means that if there is no change in the absolute value, no output will appear in the subtraction circuit 7, but if there is a change in the absolute value, In the two low-pass filter circuits 6, only the time constant difference is extracted and detected in the level determination circuit 7 at the subsequent stage. Also, the overcurrent element 16 divides the output of the bandpass filter 2 into 2
The phase is made absolute by the phase incrementing rectifier circuit 5, detected by the level detection circuit 7 which has been determined in advance by )Ω, and the change width detection element 1
As a detection element of 5, an OR circuit 9 activates a time-limited return timer 10 at the next stage, and an output is obtained from an output circuit 1. If the operation described in ``1'' is represented in a diagram, the operation characteristics will be as shown in FIG. In addition, in the conventional distance relay system, as shown in FIG. A trip circuit is configured by logical product. In the y+r a relay system configured in this way, the fault impedance Z is detected from the fault current IεI and voltage ■ generated in the grid, and the distance relay DZ is activated when the impedance is below a preset impedance.
The power transmission line is protected by an overcurrent relay 518 that detects the absolute value of the fault current i and operates when the absolute value is equal to or higher than a preset detection level. Therefore, as the overcurrent relay 518, an absolute value detection type OC relay is generally used. In this case, the load current is constantly being applied to the power transmission line, and if this value is -42 or higher than the setting value of the overcurrent relay Fils, the absolute value detection type O
To operate the C relay, the distance relay I)Z does not become a spacing. Note that there is a method to worsen the current sensitivity of the overcurrent relay 51S, but the tdε with the overcurrent relay
This is difficult because it requires sensitivity coordination. Also, in recent years, the load due to the operating principle as mentioned above? li
A range-of-change overcurrent relay that includes a range-of-change detection element that detects the absolute value change in 'tAε, and an overcurrent element of absolute value detection type as a backup of this element, and detects the logical sum of these two elements. is used. In this device, the load current alone does not cause incorrect lJ as mentioned above, so ^? Condition i is satisfied. However, in the case of a complete power outage due to a fault in the grid, the change range detection element has the disadvantage of malfunctioning if the load current flowing through the grid exceeds the sensitivity of the change range detection element. there were. [Object of the invention] The present invention provides r? The present invention has been made in view of the conventional problem described in f., and its purpose is to provide a variable width overcurrent relay that can prevent malfunction of the variable width detection element during a full stop. [Summary of the Invention] In order to achieve the above object, the present invention provides an absolute value detection type overcurrent element in which the level detection circuit output of the variation width detection element and the output of a common bandpass filter are phase-increased and rectified. TeA
An ND circuit is configured, and the output of a time-limited return timer that holds the output of the AND circuit and the output of the overcurrent element are clamped by a diode element, and in the event of a complete failure, the return output of the overcurrent element is used to force a return. let In addition, for time coordination during transient times, a time-limited operation timer is provided after the timer described in [11. We are coordinating with 111 Hours. [Embodiments of the Invention] Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 1 shows the configuration of a preferred embodiment of the present invention. In FIG. 1, 1 is a signal converter. 2; lj) band-pass filter circuit; 3, memory filter circuit; 4, adder circuit; 5, phase-increasing rectifier circuit; 6, low-pass filter circuit; 7, subtraction circuit;
is an OR circuit, and 10 is a time-limited recovery timer. ] 1 is an output circuit, 12 is an AND circuit, 13 is a diode element, 14 is a time-limited operation timer, 15 is a variation width detection element (
Δ○C), 16 is an overcurrent element (1 (○C)). 17 is an overcurrent element (LOG). The current information ■^ is taken out from the grid transmission line ``ft?'' and is sent through the signal conversion circuit 1. Then, it is input to the bandpass filter circuit 2, extracts only the fundamental wave component, and gives the signal to the change width detection element 15 and the two power wave elements 16 and 17.Next, the change width detection element 15 uses a memory filter. The signal is separated into two signals, one that passes through circuit 2 and the other that does not pass, and each is added in addition circuit 4. Memory filter circuit 3 is set so that the input and output phases are 180° at the rated frequency. , the output of the adder circuit 4 is assumed to be O in a steady state. Here, when an absolute value change of the system current occurs, a difference occurs in the human output voltage of the memory filter circuit 3, and the output of the adder circuit 4
generates an output voltage. This voltage is
The change range detection element 15 operates when the absolute value signal is extracted as an absolute value signal and exceeds a preset level. Here, if there is current distortion in the load current, the output voltage of the memory filter circuit 3 becomes the waveform-shaped fundamental wave' upper voltage, but the residual harmonic branch of the filter appears in the output of the adder circuit 4. When this output is taken as an operation value, when the load current is large, the residual 1°lli, 051 wave becomes large and affects the operating value. Therefore, after converting the output voltage of the adder circuit 4 into an absolute value which is applied to the phase-increasing fl flow circuit 5, the resistor R
1 and capacitor CI. The output voltage is passed through two low-pass filters (3) with different time constants, the resistor C2 and the capacitor C2, and the subtracter circuit 4 outputs the voltage. does not appear, but when a change appears in the absolute value, an output corresponding to the time difference of the time constant appears in the two low-pass filters 6. This output is detected in the level judgment circuit 8 in the next stage.Next In addition, the overcurrent element 17 converts the output of the bandpass filter 2 into 2
The phase is increased in phase, converted into an absolute value by the phase intensifying rectifier circuit 5, and -

[The output judged by the set level judgment circuit 8 and the change iI; + detection required 7! A time-limited return timer in which the output of L115 is generated by an AND circuit 12 and this output is held for a certain period] A diode element 13 is used to clamp between the O output and the output of the overcurrent element 17, and when the output is completely stopped,゛11i style・
Element 17 returns forcibly using the return output. In addition, in order to achieve time coordination during a transient period, a time-limited operation timer 14 is provided after the time-limited return timer 10, and a timer 14 is provided after the time-limited return timer 10.
iI delay the operation time of flow guide 15, overcurrent element]7 which time coordination is taken. In addition, the other absolute value detection type overcurrent element 1G is subjected to equal phase rectification in the same manner as the overcurrent element]7, and the level judged output is used as the output of the time limit operation timer 14 and the output of the OR circuit 9, and the change range detection element 15 Output 4 is an element when the overcurrent element 17 output does not operate. As described above, the circuit is constructed according to the operating principle described above, and as a result, the operating characteristics shown in FIG. 2 can be obtained. Incidentally, FIG. 4 shows the conventional configuration and the main parts according to this embodiment. In this embodiment, when the load current changes from constant to full stop, the absolute value detection type overcurrent element (Lot:) is used as a locking element for the change width detection element (ΔQC) by logical product to form 'η. ing. Note that the time-limited operation timer 14 is used to coordinate the transient time.
has been established. Therefore, if the operating time of the change range detection element (ΔQC) 15 and the recovery time of the overcurrent element (LOG) 17 overlap,
Prevent the output from being held by the time-limited return timer 10)
・In order to do this, the output of the timer 10 is clamped by the diode element 13 inserted between the outputs of the overcurrent element 17, and the circuit configuration is such that the overcurrent element 7 is forced to return to 11. By. Simple 11. Therefore, it is possible to realize a change width overcurrent relay that is completely malfunction-proof during a power outage in a reliable manner. [Effects of the Invention] As explained above, according to the present invention, an element that detects and locks when a complete power outage is incorporated in the variation range detection element, which in principle can detect even in the event of a total power outage failure. As a result, an excellent effect can be obtained in that a highly reliable variable range overcurrent relay that does not malfunction even during a complete power outage can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram obtained by the apparatus according to the present invention. FIG. 33 is a conventional main part configuration diagram, FIG. 4(a) is a conventional main part configuration diagram, FIG. FIG. 6 is a block diagram showing the principle of the conventional device, and FIG. 7 is a diagram showing the operating characteristics of the conventional device. 1... Signal conversion circuit, 2... JtF band pass filter circuit. 3...Memory filter circuit, 4...Addition circuit, 5...Equal phase rectifier circuit, 6...Low pass filter circuit, 7...
Subtraction circuit, 8...level judgment circuit, 9...OR circuit,
10...Limit H, Te return timer, 11...Output @ path, 12
...l\ND circuit, 13 ・Diode element, 14
- Time-limited operation timer, 15... change width detection element, 16.
17...Overcurrent element.

Claims (1)

[Claims] 1. A current-voltage converter that takes in current information of the power system, a filter circuit connected to the output of the converter, a memory circuit connected to the output of the fimeter circuit, and a connection between the output of the filter circuit and the memory circuit. an absolute value conversion circuit that compares outputs and converts the comparison output into an absolute value; a pair of low-pass filter circuits with different time constants connected to the output of the absolute value conversion circuit;
Consisting of a change width detection element that includes a comparison circuit that compares the outputs of each filter circuit and a level detection circuit that detects the output of the comparison circuit, and a first overcurrent element that is connected to the output of the filter circuit. In the change width overcurrent relay,
a second overcurrent element connected to the output of the filter circuit; an AND circuit that outputs a logical product of the change width detection force and the second overcurrent element output; and a time limit connected to the output of the AND circuit. a return timer circuit, a means for restoring the time-limited return timer output by a second overcurrent element output, a time-limited operation timer circuit connected to the output of the time-limited return timer circuit; 1. A variable width overcurrent relay comprising: an OR circuit for introducing a logical sum with an overcurrent element output into a relay output circuit.