A real-time monitoring device for the opening and closing coils of a circuit breaker

Abstract

The present invention relates to an early warning method, and particularly to a real-time monitoring device for the closing and opening coils of a circuit breaker. The real-time monitoring device for the closing and opening coils of a circuit breaker includes a closing coil, an opening coil, auxiliary contacts of the circuit breaker, and a monitoring section for the intrusion of AC voltage into DC voltage; a current monitoring branch for the closing coil is provided beside the closing coil, and a current monitoring branch for the opening coil is provided beside the opening coil; a controllable opto-coupler relay contact is added in parallel with the auxiliary contacts of the circuit breaker; a measuring branch for the DC voltage to the ground and its AC voltage is provided on the positive and negative busbars. The device of the present invention can effectively detect problems such as poor contact and coil breakage of the closing and opening coils of the DC operating coil, eliminate the interference of the auxiliary contacts of the circuit breaker and the undervoltage of the DC busbar, and monitor the problem of the intrusion of AC voltage; an isolation sensor is used to achieve complete electrical isolation between the current monitoring branches of the closing and opening coils and the closing and opening coils, and the monitored current is small, which will not affect the normal operation of the main control system of the circuit breaker.

Description

Technical Field

[0001] The present invention relates to a warning method, and more particularly to a real-time monitoring device for the closing and opening coils of a circuit breaker. Background Art

[0002] Defects in relay protection circuits are one of the main reasons for the expansion of faults. Incorrect operation of protection caused by defects in DC operating coils accounts for a relatively high proportion. Among them, poor contact of DC operating coils or breaker auxiliary contacts, coil breakage, DC undervoltage, etc. are important reasons for incorrect operation of protection. Therefore, effective monitoring and warning of DC operating coils are important means to prevent hidden faults and reduce incorrect operation of protection.

[0003] Conventional methods of directly monitoring the red and green light coils or indirectly monitoring through the normally closed contacts of position relays in series with signal coils belong to non-full-condition monitoring. After the circuit breaker closes (opens), the closing (opening) coil loses monitoring. Most manufacturers' integrated protection devices have the above monitoring and warning functions, but they do not pay enough attention to the research on the full-condition monitoring device for the closing and opening coils of the circuit breaker's DC operating coil. Currently, there are not many manufacturers that specifically engage in in-depth development in this area. Obviously, this non-full-condition monitoring has potential safety hazards. In view of the above problems, in order to ensure the smooth implementation of the eighteen anti-measures requirements and prevent defective products from flowing into the power grid operation, it is very necessary to develop a monitoring device for the closing and opening coils of the circuit breaker's DC operating coil. Summary of the Invention

[0004] The object of the present invention is to provide a real-time monitoring device for the closing and opening coils of a circuit breaker in view of the above deficiencies. By the current branches of the closing and opening coils, the current values flowing through the monitoring branches of the closing and opening coils are monitored online respectively, and whether there is a coil breakage problem is judged by comparing the monitored current with the warning set value. And the interference of the breaker auxiliary contacts is eliminated by switching the contacts of the controllable opto-coupler relay, so as to realize the integrity monitoring of the closing and opening coils; by monitoring the DC voltages of the positive and negative buses to the ground, and judging whether there is an undervoltage problem by comparing the monitored voltage with the warning set value, the undervoltage interference is eliminated. At the same time, by monitoring the small AC signals in the DC circuit, it is judged whether there is a problem of AC intrusion into the bus; this method can not only realize the integrity full-condition monitoring of the DC operating coil, but also has a very small monitored current, strong anti-interference ability, and will not affect the normal operation of the system.

[0005] The present invention is implemented by adopting the following technical solutions:

[0006] The real-time monitoring device for the closing and opening coils of a circuit breaker includes a closing coil, an opening coil, auxiliary contacts of the circuit breaker, and a monitoring section for the intrusion of AC into DC voltage. A current monitoring branch for the closing coil is provided beside the closing coil, and a current monitoring branch for the opening coil is provided beside the opening coil. A controllable opto-coupler relay contact is added in parallel to the auxiliary contacts of the circuit breaker. Measuring branches for the DC voltage and its AC voltage to the ground are provided on the positive and negative busbars.

[0007] The current monitoring branch for the closing coil includes a current-limiting resistor in the closing coil monitoring branch, a current-measuring resistor in the closing coil monitoring branch, its first isolation sensor, a normally open auxiliary contact of the first circuit breaker, and a positive terminal connection point of the closing coil, which are connected in sequence.

[0008] The current monitoring branch for the opening coil includes a current-limiting resistor in the opening coil monitoring branch, a current-measuring resistor in the opening coil monitoring branch, its second isolation sensor, a normally closed auxiliary contact of the first circuit breaker, and a positive terminal connection point of the opening coil, which are connected in sequence.

[0009] The first isolation sensor and the second isolation sensor respectively monitor the voltage drops across the current-measuring resistor in the closing coil monitoring branch and the current-measuring resistor in the opening coil monitoring branch.

[0010] A first opto-coupler relay contact is connected in parallel across the two ends of the normally open auxiliary contact of the first circuit breaker in the current monitoring branch for the closing coil; a second opto-coupler relay contact is connected in parallel across the two ends of the normally closed auxiliary contact of the first circuit breaker in the current monitoring branch for the opening coil.

[0011] In the monitoring circuit for the DC voltage and its AC component to the ground of the positive and negative busbars, the positive busbar obtains the voltage drop across the voltage-measuring resistor (i.e., the third voltage-dividing measuring resistor) R in the DC positive busbar voltage monitoring branch through the third isolation sensor PT P and the negative busbar obtains the voltage drop across the voltage-measuring resistor (i.e., the fourth voltage-dividing measuring resistor) R in the DC negative busbar voltage monitoring branch through the fourth isolation sensor PT PP N PN

[0012] By measuring the currents in the current monitoring branches of the closing coil and the opening coil and comparing them with the set preset values respectively, the present invention can determine whether there are open-circuit problems in the closing and opening coils. At the same time, by switching the opto-coupler relays connected in parallel to the auxiliary contacts of the circuit breaker, it can be determined whether it is interference from the auxiliary contacts of the circuit breaker. By monitoring the DC voltage of the positive and negative busbars, it can determine the busbar voltage interference of the closing and opening coils. At the same time, by monitoring the AC components, it can monitor the problem of AC intrusion into the positive and negative busbars.

[0013] The device of the present invention is reasonably designed and scientifically structured, and has the following advantages:

[0014] 1) High monitoring sensitivity, capable of effectively detecting problems such as poor contact or broken wires in the closing and opening coils of DC operating coils. At the same time, it can also eliminate interference from breaker auxiliary contacts and DC bus undervoltage, as well as monitor the problem of AC voltage intrusion.

[0015] 2) An isolation sensor is used to achieve complete electrical isolation between the current monitoring branch of the closing and opening coils and the closing and opening coils. Moreover, the monitored current is small, which will not affect the normal operation of the main control system of the breaker, and it has high precision, fast response, and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a circuit composition diagram of the closing coil current monitoring branch in the device of the present invention;

[0017] FIG. 2 is a circuit composition diagram of the opening coil current monitoring branch in the device of the present invention;

[0018] FIG. 3 is a schematic circuit diagram of the closing coil current monitoring circuit in the device of the present invention;

[0019] FIG. 4 is a schematic circuit diagram of the opening coil current monitoring circuit in the device of the present invention;

[0020] FIG. 5 is a logic diagram for judging a broken wire in the closing coil of the device of the present invention;

[0021] FIG. 6 is a logic diagram for judging a broken wire in the opening coil of the device of the present invention;

[0022] FIG. 7 is a structural diagram of the DC voltage and AC intrusion monitoring branch in the device of the present invention.

[0023] Figure 1 and Figure 3 in:

[0024] R LH represents the current-limiting resistor of the closing coil monitoring branch;

[0025] R CH represents the current-measuring resistor of the closing coil monitoring branch;

[0026] CT H represents the current-measuring sensor of the closing coil monitoring branch, i.e., the first isolation sensor;

[0027] OP H represents the parallel contacts at both ends of the normally open auxiliary contact of the first breaker in the closing coil monitoring branch, i.e., the first opto-coupler relay contact;

[0028] Figure 2 and Figure 4 in:

[0029] R LT represents the current-limiting resistor of the opening coil monitoring branch;

[0030] R CT represents the shunt coil monitoring branch current measurement resistor;

[0031] CT T represents the shunt coil monitoring branch current measurement sensor, i.e., the second isolation sensor;

[0032] OP T represents the parallel contacts at both ends of the normally - closed auxiliary contact of the first circuit breaker in the shunt coil monitoring branch, i.e., the second opto - coupled relay contact;

[0033] Figure 7 In:

[0034] R LP represents the DC positive bus voltage monitoring branch voltage - dividing resistor;

[0035] R PP represents the DC positive bus voltage monitoring branch voltage measurement resistor;

[0036] PT P represents the DC positive bus voltage monitoring branch voltage measurement sensor, i.e., the third isolation sensor;

[0037] R LN represents the DC negative bus voltage monitoring branch voltage - dividing resistor;

[0038] R PN represents the DC negative bus voltage monitoring branch voltage measurement resistor;

[0039] PT N represents the DC negative bus voltage monitoring branch voltage measurement sensor, i.e., the fourth isolation sensor;

[0040] In addition:

[0041] DSP represents the digital signal processor;

[0042] ADC1 - ADC4 represent the analog - to - digital converters;

[0043] Other symbols are common symbols in the circuit breaker operation loop and will not be described further. Specific implementation mode

[0044] The present invention will be further described in detail below with reference to the accompanying drawings.

[0045] The present invention provides a real - time monitoring device for the closing and opening coils of a circuit breaker, adding current monitoring branches to the conventional closing coil and opening coil respectively; adding opto - coupled relay contacts in parallel with the auxiliary contacts in the current monitoring branches of the above - mentioned closing coil and opening coil respectively; adding DC voltage and its AC component monitoring branches for the positive and negative busbars to the ground.

[0046] The closing coil current monitoring branch includes a current-limiting resistor R of the closing current monitoring branch connected in sequence LH , a current measuring resistor R of the closing coil monitoring branch CH and its first isolation sensor CT H , the normally open auxiliary contact of the first circuit breaker, and the positive terminal connection point of the closing coil;

[0047] The opening coil current monitoring branch includes a current-limiting resistor R of the opening current monitoring branch connected in sequence LT , a current measuring resistor R of the opening coil monitoring branch CT and its second isolation sensor CT T , the normally closed auxiliary contact of the first circuit breaker, and the positive terminal connection point of the opening coil;

[0048] The first isolation sensor CT H and the second isolation sensor CT T are respectively used to monitor the voltage drops on the current measuring resistor R of the closing coil monitoring branch CH and the current measuring resistor R of the opening coil monitoring branch CT .

[0049] Both ends of the normally open auxiliary contact of the first circuit breaker in the closing coil current monitoring branch are connected in parallel with the contact OP of the first opto-coupler relay H ; both ends of the normally closed auxiliary contact of the first circuit breaker in the opening coil current monitoring branch are connected in parallel with the contact OP of the second opto-coupler relay T .

[0050] In the monitoring circuit of the DC voltage and its AC component of the positive and negative busbars to the ground, the positive busbar obtains the voltage drop on the third voltage-dividing measuring resistor (the voltage measuring resistor R of the DC positive busbar voltage monitoring branch P ) through the third isolation sensor PT PP , and the negative busbar obtains the voltage drop on the fourth voltage-dividing measuring resistor (the voltage measuring resistor R of the DC negative busbar voltage monitoring branch N ) through the fourth isolation sensor PT PN .

[0051] By measuring the currents of the closing coil and opening coil current monitoring branches and comparing them with the set preset values respectively, the present invention can judge whether there is an open circuit problem in the closing and opening coils. At the same time, by switching the opto-coupler relay connected in parallel with the auxiliary contact of the circuit breaker, it can judge whether it is interference from the auxiliary contact of the circuit breaker.

[0052] By monitoring the DC voltage of the positive and negative busbars, the busbar voltage interference of the closing and opening coils can be judged. At the same time, by monitoring the AC component, the problem of AC intrusion into the positive and negative busbars can be monitored.

[0053] The process of monitoring the closing coil current is asFigure 1 As shown in the figure, it includes:

[0054] This branch starts from the positive bus connection point and first passes through the current-limiting resistor R of the closing coil monitoring branch LH , and then samples the current measurement resistor R of the closing coil monitoring branch CH , the normally open auxiliary contact QF3 of the first circuit breaker, and the positive terminal connection point of the closing coil. This circuit does not need to change other control coil branches of the original integrated protection, only the positive bus connection point, the positive terminal connection point of the closing coil, and the normally open auxiliary contact QF3 of the circuit breaker need to be reserved. Figure 3 Figure Figure 5 is the specific circuit execution diagram of the above circuit. The sampling resistor divides a voltage within 200 mV and sends it to the ADC1 interface of the DSP (Digital Signal Processor) through the first isolation sensor and the corresponding conditioning circuit. The DSP converts the collected data into the corresponding actual current value. The actual current flowing through the circuit is about 10 mA. Therefore, by comparing the collected current value with the warning set value of 8 mA, it can be initially judged whether there is a break phenomenon. In addition, the device is connected in parallel with the first opto-coupled normally open relay contact at both ends of the normally open auxiliary contact QF3 of the circuit breaker. After the monitored collected current value is less than the warning set value of 8 mA, the DSP starts the corresponding IO1 output to make the opto-coupled normally open relay contact close. If the monitored collected current value is still less than the warning set value of 8 mA within a short period of time thereafter, it can be basically judged that there is a break phenomenon. See the specific warning logic in

[0055] The process of monitoring the opening coil current is as shown in Figure 2 the figure, and it includes:

[0056] This branch starts from the positive bus connection point and first passes through the current-limiting resistor R LT , and then samples the resistor R CT , the normally open auxiliary contact QF4 of the second circuit breaker, and the positive terminal connection point of the opening coil. The specific execution circuit and process are the same as those of the closing coil current monitoring. For details, see Figure 4 , and its corresponding specific warning logic can be seen in Figure 6 .

[0057] The circuit principle of the AC intrusion warning can be seen in Figure 7 , the positive and negative bus voltage-dividing resistors (voltage measurement resistors of the DC positive bus voltage monitoring branch) R PP , (voltage measurement resistor of the DC negative bus voltage monitoring branch) R PNThe voltages on [it] enter ADC3 and ADC4 of the DSP (Digital Signal Processor) respectively after passing through their respective isolation sensors and conditioning circuits. Finally, after the FFT calculation of the DSP, the corresponding AC voltage values are obtained and compared with the set reference values. If any side is greater than or both sides are greater than the set reference value (10V), it can be determined that there is a problem of AC intrusion into the positive and negative busbars, and an early warning signal is immediately reported. In addition, the corresponding DC voltage value needs to be sampled by this branch and compared with the DC under-voltage reference value (80% * 220V or 80% * 110V) to participate in Figure 5 and Figure 6 the logical judgment to avoid false alarms of the closing and opening coils caused by under-voltage.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of the claims of the present invention pending approval.

Claims

1. A real-time monitoring device for the opening and closing coils of a circuit breaker, characterized in that: It includes a closing coil and a tripping coil, auxiliary contacts of the circuit breaker, and a monitoring section for DC voltage and AC intrusion; a current monitoring branch for the closing coil is provided beside the closing coil, and a current monitoring branch for the tripping coil is provided beside the tripping coil; a controllable opto-coupler relay contact in parallel is added to the auxiliary contacts of the circuit breaker; DC voltage and its AC voltage measurement branches are provided on the positive and negative busbars. The current monitoring branch for the closing coil includes a current-limiting resistor for the closing coil monitoring branch, a current measurement resistor for the closing coil monitoring branch, a normally open auxiliary contact of the first circuit breaker, and a positive terminal connection point of the closing coil connected in sequence; the current measurement resistor for the closing coil monitoring branch is in parallel with the first isolation sensor. The current monitoring branch for the tripping coil includes a current-limiting resistor for the tripping coil monitoring branch, a current measurement resistor for the tripping coil monitoring branch, a normally closed auxiliary contact of the first circuit breaker, and a positive terminal connection point of the tripping coil connected in sequence; the current measurement resistor for the tripping coil monitoring branch is in parallel with the second isolation sensor. The first isolation sensor and the second isolation sensor respectively monitor the voltage drops on the current measurement resistors of the closing coil monitoring branch and the tripping coil monitoring branch. The current warning set values of the current monitoring branch for the closing coil and the current monitoring branch for the tripping coil are 8 mA, and are used as the basis for judging whether there is an open circuit in the closing coil and the tripping coil; by measuring the currents of the current monitoring branch for the closing coil and the current monitoring branch for the tripping coil and comparing them with the current warning set values respectively, it is judged whether there is an open circuit problem in the closing coil and the tripping coil, and at the same time, by switching the controllable opto-coupler relay in parallel with the auxiliary contacts of the circuit breaker, it is judged whether it is interference from the auxiliary contacts of the circuit breaker. The DC voltage of the positive and negative busbars is used as the basis for the busbar voltage interference of the closing and tripping coils. The reference value set for the voltage on the voltage-dividing resistors of the positive and negative busbars is 10 V, which is used as the basis for determining the presence of AC intrusion in the positive and negative busbars. The signal data of the first isolation sensor and the second isolation sensor enter the DSP digital signal processor through the ADC interface, and the corresponding AC voltage values are obtained through the FFT calculation of the DSP. The corresponding DC voltage value obtained by the DC voltage and its AC voltage measurement branch to the ground is used as the basis for avoiding false alarms of the closing and tripping coils caused by undervoltage.

2. The real-time monitoring device for the opening and closing coils of a circuit breaker according to claim 1, characterized in that: A first opto-coupler relay contact is connected in parallel across the two ends of the normally open auxiliary contact of the first circuit breaker in the current monitoring branch for the closing coil; a second opto-coupler relay contact is connected in parallel across the two ends of the normally closed auxiliary contact of the first circuit breaker in the current monitoring branch for the tripping coil.

3. The real-time monitoring device for the opening and closing coils of a circuit breaker according to claim 2, characterized in that: In the DC voltage and its AC voltage measurement branches for the ground, the positive bus passes through the third isolation sensor PT P to obtain the voltage drop across the voltage measurement resistor R PP in the DC positive bus voltage monitoring branch, and the negative bus passes through the fourth isolation sensor PT N to obtain the voltage drop across the voltage measurement resistor R PN in the DC negative bus voltage monitoring branch.

4. The monitoring method of a real-time monitoring device for the opening and closing coils of a circuit breaker according to claim 3, characterized in that: By monitoring the DC voltage of the positive and negative busbars, the busbar voltage interference of the closing and tripping coils is judged, and at the same time, by monitoring the AC component, the problem of AC intrusion into the positive and negative busbars is monitored.

5. The monitoring method of a real-time monitoring device for opening and closing coils of a circuit breaker according to claim 4, characterized in that, The process of monitoring the current of the closing coil includes: (1)The closing coil current monitoring branch starts from the positive bus connection point, first passes through the current-limiting resistor of the closing coil monitoring branch, then through the current measurement resistor of the closing coil monitoring branch, and then through the normally open auxiliary contact of the first circuit breaker to reach the positive terminal connection point of the closing coil; the closing coil current monitoring branch does not need to change other control coil branches of the original integrated protection, and only needs to leave the positive bus connection point, the positive terminal connection point of the closing coil, and the normally open auxiliary contact of the circuit breaker. (2)The current measurement resistor of the closing coil monitoring branch divides a voltage within 200 mV and sends it into the ADC1 interface of the DSP digital signal processor through the first isolation sensor and the corresponding conditioning circuit. The DSP converts the collected data into the corresponding actual current value; the current flowing through the actual circuit is about 10 mA. By comparing the collected current value with the warning set value of 8 mA, it can be preliminarily judged whether there is a break phenomenon. (3)The device connects the first opto-coupled relay contact in parallel across the two ends of the normally open auxiliary contact QF3 of the first circuit breaker. After the collected current value monitored is less than the warning set value of 8 mA, the DSP closes the first opto-coupled relay contact by starting the corresponding IO1 output. If the collected current value monitored is still less than the warning set value of 8 mA within a short period of time thereafter, it is basically judged that there is a break phenomenon. When the judgment results of steps (2) and (3) both indicate a break phenomenon, it is finally determined that the closing coil is broken, thereby eliminating the interference of the normally open auxiliary contact and the DC voltage, and being able to monitor the situation where the normally open auxiliary contact is not in place.

6. The monitoring method of a real-time monitoring device for opening and closing coils of a circuit breaker according to claim 5, characterized in that, The process of monitoring the opening coil current includes: (1)The opening coil current monitoring branch starts from the positive bus connection point, first passes through the current-limiting resistor of the opening coil monitoring branch, then through the current measurement resistor of the opening coil monitoring branch, and then through the normally closed auxiliary contact of the first circuit breaker to reach the positive terminal connection point of the opening coil; the specific implementation circuit and process are the same as those of the closing coil current monitoring. (2)Positive and negative bus voltage-dividing resistors R PP That is, the voltage measurement resistors for the DC positive bus voltage monitoring branch and the DC negative bus voltage monitoring branch, resistor R PN After the voltages on them pass through their respective isolation sensors and conditioning circuits, they enter ADC3 and ADC4 of the DSP digital signal processor respectively. Finally, through the FFT calculation of the DSP, the corresponding AC voltage values are obtained and compared with the set reference values. If either side or both sides are greater than the set reference value, it can be determined that there is a problem of AC intrusion into the positive and negative buses, and an early warning signal is immediately reported.

7. The monitoring method of a real-time monitoring device for the opening and closing coils of a circuit breaker according to claim 6, characterized in that, The DC voltage to ground and its AC voltage measurement branch also need to obtain the corresponding DC voltage value and compare it with the DC voltage undervoltage reference value. Through logical judgment, false alarms of the opening and closing coils caused by undervoltage are avoided.

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