CN111308334A - A current type relay protection trip circuit contact resistance detection device - Google Patents

Abstract

The application discloses a contact resistance detection device of a current-type relay protection trip circuit. The contact resistance detection device of the relay protection trip circuit provided by the present application, by adding a detection circuit on the basis of the trip circuit, and based on the current difference between the detection resistor connected to the trip circuit and disconnected from the trip circuit, by adding a detection circuit to the trip circuit. The contact resistance test result of the trip circuit can be obtained by comparing the standard deviation value of the set value, which solves the technical problem of poor reliability of the existing relay protection trip circuit caused by the failure of the existing relay protection device and the secondary circuit to measure the contact resistance in time. .

Description

A current type relay protection trip circuit contact resistance detection device

technical field

The present application relates to the technical field of relay protection, and in particular, to a contact resistance detection device of a relay protection trip circuit.

Background technique

In the currently used power system relay protection trip circuit, since the tripping outlet pressure plate passes through the trip holding relay coil, and then passes through the circuit breaker position contact to the trip coil, the entire circuit goes from the protection chamber to the outdoor switch site, and the cables involved are long. In the intermediate link, it is difficult to avoid the problem of increased contact resistance of the trip circuit due to reasons such as secondary cable disconnection, loose terminal block terminals, poor contact of the pressure plate or equipment aging, which will eventually cause the trip circuit to fail, causing the switch to refuse to move, and may even lead to grid accidents. and cause significant economic losses.

The contact resistance inspection of the existing relay protection trip circuit is carried out by manual periodic inspection, and it is difficult to measure the size of the circuit contact resistance in time, which leads to the technical problem of poor reliability of the existing relay protection trip circuit.

SUMMARY OF THE INVENTION

The embodiment of the present application provides a current-type relay protection trip circuit contact resistance detection device, which is used to solve the technical problem of poor reliability of the existing relay protection trip circuit contact resistance detection device.

In view of this, the present application provides a current-type relay protection trip circuit contact resistance detection device, which is set in association with the trip circuit, and the trip circuit includes: a position relay, a trip outlet pressure plate, a trip hold relay, a trip coil, and a protection trip. The contact point and the circuit breaker position contact point, the positive electrode of the voltage source, the protection trip contact point, the trip outlet pressure plate, the coil of the trip holding relay, the circuit breaker position contact point, the trip coil and the voltage source negative electrode are connected in series in sequence, so The contact point of the trip hold relay is connected in parallel with the protection trip point and the trip outlet pressure plate, the position relay is connected in parallel with the coil of the trip hold relay, and the relay protection trip circuit contact resistance detection device includes: a detection circuit;

The detection loop includes: a detection switch, a detection resistor and a controller;

The positive electrode of the voltage source, the detection switch and the detection resistor are connected in series in sequence, and are connected in parallel with the protection trip contact;

A current detection point is arranged between the parallel point of the coil of the trip holding relay and the position relay and the position contact of the circuit breaker;

The controller is used to control the detection switch to open or close, and to measure the first state current at the current detection point when the control switch is open and the current detection point when the control switch is closed. The measured difference value of the obtained second state current is compared with a preset standard deviation value to obtain a contact resistance detection result.

Optionally, the controller is specifically used for:

Control the detection switch to open or close, and measure the first state current at the current detection point when the control switch is open and the second state current at the current detection point when the control switch is closed The measured difference value is compared with the preset standard deviation value. If the measured difference value is greater than the standard deviation value, the output contact resistance is too large; if not, the output contact resistance is normal.

Optionally, the detection resistor is specifically an adjustable resistor.

As can be seen from the above technical solutions, the embodiments of the present application have the following advantages:

The application provides a current-type relay protection trip circuit contact resistance detection device, including: a detection circuit; the detection circuit includes: a detection switch, a detection resistance and a controller; the positive electrode of the voltage source, the detection switch and the The detection resistors are connected in series in sequence and connected in parallel with the protection trip contact; a current detection point is set between the parallel connection point of the coil of the trip holding relay and the position relay and the position contact of the circuit breaker; the controller is used for Control the detection switch to open or close, and measure the first state current at the current detection point when the control switch is open and the second state current at the current detection point when the control switch is closed The measured difference value is compared with the preset standard deviation value to obtain the contact resistance detection result.

The contact resistance detection device of the relay protection trip circuit provided by the present application, by adding a detection circuit on the basis of the trip circuit, and based on the current difference between the detection resistor connected to the trip circuit and disconnected from the trip circuit, and the preset The test result of the contact resistance of the trip circuit is obtained by comparing the predetermined standard deviation value, which solves the technical problem of poor reliability of the existing relay protection trip circuit caused by the failure of the existing relay protection device and the secondary circuit to measure the contact resistance in time. .

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a current-type relay protection trip circuit contact resistance detection device and a trip circuit provided by the application.

Detailed ways

The embodiment of the present application provides a current-type relay protection trip circuit contact resistance detection device, which is used to solve the technical problem of poor reliability of the existing relay protection trip circuit contact resistance detection device.

In order to make the purpose, features and advantages of the invention of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the following The described embodiments are only some, but not all, embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

Referring to FIG. 1, the first embodiment of the present application provides a current-type relay protection trip circuit contact resistance detection device, which includes: a detection circuit on the basis of the existing trip circuit;

Wherein, the trip circuit of this embodiment includes: position relay R ₁ , trip outlet pressure plate K ₁ , trip hold relay, trip coil R ₂ , protection trip contact BT and circuit breaker position contact DL; positive voltage source, protection trip contact BT, The trip outlet pressure plate K ₁ , the coil TBJI of the trip hold relay, the position contact DL of the circuit breaker, the trip coil R ₂ and the negative electrode of the voltage source are connected in series in sequence _; Relay R1 and the coil _TBJI of the trip holding relay are connected in parallel.

The detection loop includes: a detection switch K ₂ , a detection resistor R ₄ and a controller (not shown);

_The positive pole of the voltage source, the detection switch K2 and the detection resistor R4 are connected in series in sequence, and are connected in parallel with the protection trip contact BT _;

A current detection point is set between the parallel point of the coil _TBJI of the trip holding relay and the position relay R1 and the position contact DL of the circuit breaker;

The controller is used to control the detection switch to open or close, and to measure the difference between the first state current measured at the current detection point when the control switch is turned off and the second state current measured at the current detection point when the control switch is closed and the preset value. The determined standard deviation value is compared to obtain the contact resistance test result.

It should be noted that, as shown in FIG. 1 . The DC voltage U _dc between the positive and negative poles, the equivalent resistance R ₁ of the switch position relay, the equivalent resistance R ₂ of the trip coil, and the resistance value of the detection resistance when the detection switch K ₂ is closed is R ₄ , and the above quantities are all known quantities. TBJI is the equivalent resistance of the current coil of the trip holding relay, which can be ignored in the calculation due to its small resistance. TBJ is the action contact of the trip holding relay, BT is the protection trip contact, and DL is the position contact of the circuit breaker. When the circuit breaker is in the closing position, the DL contact is closed and its resistance can be ignored. The TBJ and BT contacts are disconnected. _R3 is the contact resistance.

Further, the controller is specifically used for:

Control the detection switch to open or close, and measure the first state current at the current detection point when the control switch is opened and the current detection point when the control switch is closed to measure the measurement difference of the second state current and the preset standard Compare the difference values. If the measured difference value is greater than the standard deviation value, the output contact resistance is too large; if not, the output contact resistance is normal.

More specifically, the detection process specifically executed by the controller of this embodiment is as follows:

1) When the detection switch is disconnected, measure and record the trip circuit current I=I ₀ of the detection point;

₂ ) Close the detection switch and connect the detection resistor R4 to the loop, measure and record the current I= _I1 at the detection point of the tripping loop;

3) Calculate the current change ΔI=I ₁ -I ₀ at the detection point according to the obtained current detection results I ₀ and I ₁ , when ΔI is greater than a certain preset value ΔI _ref , it is considered that the detection loop contact resistance R ₃ is too large and sends out early warning;

The selection method of the preset value ΔI _ref can be calculated in advance according to specific circuit parameters. Taking a 220kV line protection trip circuit as an example, the above parameters are generally: R ₁ =25580Ω, R ₂ =200Ω, R ₄ =4000Ω, assuming that the contact resistance value is 100Ω, under the above circuit parameters, according to the circuit relationship can be calculated I ₀ =8.534mA, I ₁ =58.924mA, the current change at the detection point ΔI=I ₁ -I ₀ =50.39mA.

Therefore, the preset value ΔI _ref =50.39mA can be taken at this time, that is, when the current change of the detection point is greater than 50.39mA, it means that the resistance of the contact resistance is greater than 100Ω, and the detection circuit should issue an early warning.

Wherein, the early warning message in this embodiment may be sent out in one or more manners of an optical signal alarm, an acoustic signal alarm, and a message signal alarm, which is not specifically limited herein.

For other circuit parameters, the current variation preset value ΔI _ref may take different values, but the calculation principles and criteria are still the same as those mentioned in this embodiment.

Further, the detection resistor is specifically an adjustable resistor.

The relay protection trip circuit contact resistance detection device provided by the embodiment of the present application, by adding a detection circuit on the basis of the trip circuit, and based on the current difference between the detection resistor connected to the trip circuit and disconnected from the trip circuit, by adding a detection circuit to the trip circuit. The detection result of the contact resistance of the trip circuit is obtained by comparing the preset standard deviation value, which solves the problem of poor trip reliability of the existing relay protection device caused by the failure of the existing relay protection device and the secondary circuit to measure the contact resistance in time. technical problem.

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limitations on this application. Furthermore, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

Unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood in specific situations.

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: The technical solutions described in the embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the present application.

Claims (3)

1. A current-type relay protection trip circuit contact resistance detection device, set in association with the trip circuit, the trip circuit comprising: a position relay, a trip outlet pressure plate, a trip hold relay, a trip coil, a protection trip contact and a circuit breaker position contact , the positive pole of the voltage source, the protection trip contact, the trip outlet pressure plate, the coil of the trip hold relay, the position contact of the circuit breaker, the trip coil and the negative pole of the voltage source are connected in series in sequence, and the contact point of the trip hold relay It is connected in parallel with the protection trip contact and the trip outlet pressure plate, and the position relay and the coil of the trip hold relay are connected in parallel. It is characterized in that the relay protection trip circuit contact resistance detection device includes: a detection circuit; The detection loop includes: a detection switch, a detection resistor and a controller; The positive electrode of the voltage source, the detection switch and the detection resistor are connected in series in sequence, and are connected in parallel with the protection trip contact; A current detection point is arranged between the parallel point of the coil of the trip holding relay and the position relay and the position contact of the circuit breaker; The controller is used to control the detection switch to open or close, and to measure the first state current at the current detection point when the control switch is open and the current detection point when the control switch is closed. The measured difference value of the obtained second state current is compared with a preset standard deviation value to obtain a contact resistance detection result. 2. The relay protection trip circuit contact resistance detection device according to claim 1, wherein the controller is specifically used for: Control the detection switch to open or close, and measure the first state current at the current detection point when the control switch is open and the second state current at the current detection point when the control switch is closed The measured difference value is compared with the preset standard deviation value. If the measured difference value is greater than the standard deviation value, the output contact resistance is too large; if not, the output contact resistance is normal. 3 . The contact resistance detection device of a relay protection trip circuit according to claim 1 , wherein the detection resistance is specifically an adjustable resistance. 4 .

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