CN114578222A - Low-voltage apparatus on-line monitoring method and system - Google Patents
Low-voltage apparatus on-line monitoring method and system Download PDFInfo
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- CN114578222A CN114578222A CN202210482868.4A CN202210482868A CN114578222A CN 114578222 A CN114578222 A CN 114578222A CN 202210482868 A CN202210482868 A CN 202210482868A CN 114578222 A CN114578222 A CN 114578222A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/005—Testing of electric installations on transport means
- G01R31/008—Testing of electric installations on transport means on air- or spacecraft, railway rolling stock or sea-going vessels
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3277—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
- G01R31/3278—Testing of circuit interrupters, switches or circuit-breakers of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches of relays, solenoids or reed switches
Abstract
The invention discloses a low-voltage apparatus on-line monitoring method and a system, wherein the low-voltage apparatus on-line monitoring method comprises the following steps: s01, selecting a time period; s02, applying an alternating current excitation source at two ends of the contact; s03, acquiring contact resistance state data; s04, disconnecting the connection between the two ends of the contact and the AC excitation source; s05, carrying out digital filtering on the contact resistance state data; s06, calculating the contact resistance value; s07, judging whether the contact resistance value is in a first preset range; if yes, jumping to S11; if not, executing S08; s08, repeatedly executing S02-S06 to obtain M groups of contact resistance values; s09, calculating the mean square deviation value of the resistance values of the contacts; s10, selecting a group of contact resistance values with the mean square deviation value closest to 0, and calculating an average value; and S11, judging the running state of the first low-voltage apparatus according to the contact resistance value in the first preset range or the average value in the S10.
Description
Technical Field
The invention belongs to the technical field of low-voltage apparatus application, and particularly relates to a low-voltage apparatus on-line monitoring method and system.
Background
In the entire vehicle system of vehicles such as subways and the like, in order to meet the requirements of vehicle intellectualization, informatization and continuous development of intelligent operation and maintenance, a low-voltage electric appliance becomes one of essential components in the entire vehicle system. At present, common low-voltage electrical appliances in a finished automobile system comprise a contactor, a relay, a circuit breaker and the like, and the normal use of the low-voltage electrical appliances is significant for realizing, controlling and protecting various related key function loops of the finished automobile system, so that higher requirements are put forward for the quality and the reliability of the low-voltage electrical appliances. However, low voltage appliances suffer from various failures in use. When the low-voltage apparatus fails due to a fault, the load of the low-voltage apparatus cannot be powered on or powered off, and the load is burnt or even on fire.
The common faults of the current contactor and the relay are as follows:
a mechanical structural failure fault comprising: 1. the spring/reed is over-travel, and the magnetic force of the iron core is super strong, so that an electric signal bounces; 2. the spring is blocked, deformed or rusted, the magnetic force of the iron core is removed, and the action time of the relay or the contactor is overlong; 3. the reed/armature is broken, and the contact is seriously abraded, so that the relay or the contactor does not act for many times;
a contact failure fault comprising: 1. the contact is broken due to arc discharge and melting, so that the relay or the contactor has long action time; 2. the contact oxide causes high impedance, so that the conduction cannot be realized, and the relay or the contactor does not act for many times;
a coil failure fault comprising: 1. the turn-to-turn short circuit of the coil causes the current flowing through the coil to be increased and the magnetic force to be too strong, so that the electric signal bounces; 2. the magnetic force subsides as the coil opens, causing the relay or contactor to be inactive for a number of times.
In the prior art, the fault monitoring of the relay and the contactor usually adopts an automatic or manual maintenance mode in a lower line state, the fault cannot be timely checked out in the mode, and the timeliness is poor. In the prior art, an on-line monitoring scheme for the relay and the contactor is also provided, in the on-line monitoring, constant voltage source or constant current source excitation is applied to a coil and a contact of the relay and the contactor, corresponding voltage values or current values of the coil and the contact excitation loop are acquired, characteristic parameter state data such as a coil resistance value and a contact resistance value are obtained through calculation, the running state of the relay and the contactor is judged according to the characteristic parameter state data, and during on-line monitoring, the acquired characteristic parameter state data can be interfered by external signals to various degrees. Such as: if the load at the rear end of the control loop where the contacts of the relay and the contactor are located is a pure resistive load, the external interference is light; if the rear end load of the control loop where the contacts of the relay and the contactor are located is a non-pure resistive load such as a motor, equipment, a communication device and the like, the external interference is heavier at the moment. Therefore, the measured characteristic parameter state data is inaccurate, and errors occur in the judgment of the running states of the relay and the contactor. Therefore, research on the realization of high-accuracy online monitoring of the relay and the contactor is necessary. In addition, in prior art, to the monitoring of circuit breaker in whole car system, often use hall sensor to monitor the operating current of circuit breaker, judge the tripping operation incident of circuit breaker on this basis, and concrete judgement process is: and if the working current of the circuit breaker is instantly reduced to zero from the normal working current value, judging that the circuit breaker has a tripping event. However, when the working current of the circuit breaker changes due to specific changes of some loads, the working current of the circuit breaker also instantaneously reduces to zero from the normal working current value, so that misjudgment and misreporting of a trip event are caused, and a lot of unnecessary manual inspection work is caused.
Disclosure of Invention
The invention aims to overcome one or more defects in the prior art and provides a method and a system for online monitoring of a low-voltage apparatus.
The purpose of the invention is realized by the following technical scheme:
a first part:
the first part provides a low-voltage apparatus on-line monitoring method, wherein the low-voltage apparatus comprises a first low-voltage apparatus and a second low-voltage apparatus; the first low-voltage electrical apparatus comprises at least one of a contactor and a relay; the second low-voltage electrical appliance comprises a circuit breaker; the low-voltage electric appliance on-line monitoring method comprises at least one of a first low-voltage electric appliance on-line monitoring method and a second low-voltage electric appliance on-line monitoring method; the first low-voltage apparatus online monitoring method comprises the following steps:
s01, selecting a time period within which the first low-voltage apparatus is conducted;
s02, applying an alternating current excitation source to two ends of a contact of the first low-voltage apparatus;
s03, acquiring contact resistance state data of the first low-voltage apparatus;
s04, disconnecting the two ends of the contact of the first low-voltage apparatus from the AC excitation source;
s05, carrying out digital filtering on the contact resistance state data;
s06, calculating the contact resistance value according to the filtered contact resistance state data;
s07, judging whether the contact resistance value is in a first preset range; if yes, jumping to S11; if not, executing S08;
s08, repeatedly executing S02-S06 to obtain M groups of contact resistance values, wherein each group of contact resistance values comprises N contact resistance values;
s09, respectively calculating the mean square difference value of the resistance values of the contacts;
s10, selecting a group of contact resistance values with the mean square deviation value closest to 0, and calculating the average value of all contact resistance values in the group of contact resistance values;
and S11, judging the running state of the first low-voltage apparatus according to the contact resistance value in the first preset range or the average value of the contact resistance values obtained in the S10.
In a further improvement, in S05, the digital filtering is fourier transform filtering, and the fourier transform filtering obtains contact resistance state data having the same frequency as the ac excitation source.
In a further improvement, the S08 includes the following sub-steps:
SS01, repeatedly executing S02-S06 to obtain N contact resistance values which are marked as the same group;
SS02, selecting different M-1 time periods;
and SS03, executing S02-S06 in each selected time period to obtain M-1 groups of contact resistance values, wherein each group of contact resistance values comprises N contact resistance values.
Further improved, the duration of the time period in S01 is greater than the sum of the execution time of S01 to S07 and the execution time of SS 01.
In a further improvement, the following steps are also included between S04 and S05: hardware filtering is performed on the contact resistance state data.
In a further improvement, the second low-voltage apparatus online monitoring method includes:
the method comprises the steps of SSS01, continuously acquiring breaker state data of the breaker, wherein the breaker state data comprise a working current value and working time corresponding to the working current value, and judging whether the working current value is 0; if yes, determining that the circuit breaker is tripped, and executing SSS 02; if not, SSS01 is executed;
and SSS02, calculating the duration that the working current value of the circuit breaker is equal to 0, if the duration is greater than or equal to a first preset period and/or the peak current in n milliseconds before the circuit breaker is tripped is greater than the rated current of the circuit breaker, determining that the circuit breaker tripping event is an effective tripping event, and otherwise, determining that the circuit breaker tripping event is an ineffective tripping event and filtering.
In a further improvement, the breaker state data also comprises a circuit voltage value of the breaker; the method also comprises the following steps after confirming that the circuit breaker tripping event is an effective tripping event:
if the voltage value of a loop where the circuit breaker is located does not drop or the drop value is smaller than the first threshold value in the second preset period, re-identifying the effective tripping event as an ineffective tripping event and filtering the ineffective tripping event;
the second preset period is a time interval between a working time T1 when the working current value of the circuit breaker is a non-zero value and a working time T2 when the working current value of the circuit breaker is 0.
In a further improvement, the step S11 further includes the following steps:
acquiring coil resistance state data of a first low-voltage apparatus;
calculating the coil resistance value of the first low-voltage electrical apparatus according to the coil resistance state data;
acquiring coil power-on state data of a first low-voltage electrical appliance, wherein the coil power-on state data comprises a coil power-on time value;
acquiring contact closing state data of a first low-voltage apparatus, wherein the contact closing state data comprises a contact closing time value;
calculating the action time of the first low-voltage electrical apparatus according to the coil power-on state data and the contact closing state data of the first low-voltage electrical apparatus and accumulating the action times, wherein the action time is the difference between the contact closing time value and the coil power-on time value, and the counting condition of the action times is that the coil is powered on and then the contact is closed and counted as one action;
performing alarm judgment according to the contact resistance value within a first preset range or the average value of the contact resistance values obtained in S10, the coil resistance value, the action time and the action times, and obtaining a first judgment result;
and if the first judgment result accords with the alarm condition, sending a fault alarm signal.
The first part brings the following beneficial effects:
(1) the collected contact resistance state data of the first low-voltage apparatus are subjected to digital filtering, interference of non-alternating current excitation source frequency is filtered, accuracy of the calculated contact resistance value is judged, and when the contact resistance value is inaccurate due to external interference, a mean square error optimization algorithm is further adopted to optimize multiple groups of contact resistance values. Through a mean square error optimization algorithm, the influence of the near frequency interference and the harmonic interference of the frequency of the non-alternating current excitation source which is difficult to filter by digital filtering on the accuracy of the contact resistance value is reduced, so that the accuracy of the contact resistance value detection is improved, and the performance of the on-line monitoring system of the low-voltage electrical appliance is improved. Compared with a more complex digital filtering method or a more complex excitation acquisition circuit, the mean square error optimization algorithm has the advantages that the requirement on the operational capability of the low-voltage apparatus on-line monitoring system is lowered, meanwhile, the design of the excitation acquisition circuit is simplified, and the production cost is saved.
(2) The trip event is accurately judged, and the false alarm trip event is filtered, so that the workload of manual inspection caused by the false alarm trip event of the circuit breaker is reduced, and the performance of the low-voltage electric appliance online monitoring system is improved.
(3) And according to the contact resistance value, the coil resistance value, the action time and the action times, the fault alarm of the first low-voltage apparatus is carried out based on the set alarm condition, the fault and the potential safety hazard of the first low-voltage apparatus are found in time, and the safety performance of the whole vehicle system where the low-voltage apparatus is located is improved.
The second part
The second part provides a low-voltage apparatus on-line monitoring system based on the low-voltage apparatus on-line monitoring method of the first part, and the low-voltage apparatus on-line monitoring system comprises a power panel, a first low-voltage apparatus acquisition panel and a main control panel;
the power panel is used for supplying power to the main control panel and the first low-voltage electrical apparatus acquisition panel;
the first low-voltage electric appliance acquisition board comprises a first data acquisition unit, a second data acquisition unit, a third data acquisition unit, a fourth data acquisition unit and a first MCU (microprogrammed control Unit);
the first data acquisition unit is used for detecting the coil power-on state data of the first low-voltage apparatus and sending the coil power-on state data to the first MCU;
the second data acquisition unit is used for detecting contact closing state data of the first low-voltage apparatus and sending the contact closing state data to the first MCU control unit;
the third data acquisition unit is used for detecting coil resistance state data of the first low-voltage apparatus and sending the coil resistance state data to the first MCU control unit;
the fourth data acquisition unit is used for detecting contact resistance state data of the first low-voltage apparatus and sending the contact resistance state data to the first MCU control unit;
the first MCU control unit is used for judging whether the coil of the first low-voltage electrical appliance is electrified or not and whether the contact is closed or not according to the coil electrification state data and the contact closing state data, and if the coil electrification, the contact closing and the contact closing time value are within any one time period, the connection between the third data acquisition unit and the coil of the first low-voltage electrical appliance is connected, and the connection between the fourth data acquisition unit and the contact of the first low-voltage electrical appliance is connected;
the first MCU control unit is also used for sending the coil power-on state data, the contact closing state data, the coil resistance state data and the contact resistance state data to the main control board;
the main control board calculates a coil resistance value, a contact resistance value, action time and action times according to the coil power-on state data, the contact closing state data, the coil resistance state data and the contact resistance state data, and judges the running state of the first low-voltage electric appliance according to the coil resistance value, the contact resistance value, the action time and the action times.
In a further improvement, the low-voltage apparatus online monitoring system further comprises a circuit breaker acquisition module, and the power panel is also used for supplying power to the circuit breaker acquisition module; the circuit breaker acquisition module is used for detecting circuit breaker state data and sending the circuit breaker state data to the main control board, and the main control board filters invalid tripping event and confirms valid tripping event according to the circuit breaker state data.
In a further improvement, the low-voltage apparatus on-line monitoring system further comprises an operation and maintenance control module and a communication board; the main control board is in communication connection with the operation and maintenance control module through a communication board; the operation and maintenance control module is used for receiving the operation state data of the first low-voltage apparatus transmitted by the main control board and sending out a fault alarm signal according to the operation state data of the first low-voltage apparatus; the operation and maintenance control module is also used for receiving the effective tripping event of the circuit breaker transmitted by the main control panel and sending a tripping alarm signal according to the effective tripping event of the circuit breaker.
In a further improvement, the fourth data acquisition unit comprises an alternating current excitation source, a first electrical isolating switch, a second electrical isolating switch, a current acquisition circuit and a first level acquisition circuit; the positive pole of the alternating current excitation source is connected with the first input end of the current acquisition circuit, the second input end of the current acquisition circuit is connected with the input end of the first electric isolating switch, the output end of the current acquisition circuit is connected with the first acquisition end of the first MCU control unit, the output end of the first electric isolating switch is respectively connected with the first contact end of the first low-voltage electric appliance and the first input end of the first level acquisition circuit, the second contact end of the first low-voltage electric appliance is respectively connected with the input end of the second electric isolating switch and the second input end of the first level acquisition circuit, the output end of the second electric isolating switch is connected with the negative end of the alternating current excitation source, and the output end of the first level acquisition circuit is connected with the second acquisition end of the first MCU control unit; the first MCU control unit is also used for controlling the first electrical isolating switch and the second electrical isolating switch to be switched on or switched off.
In a further improvement, the breaker acquisition module comprises a BDU module and a second level acquisition circuit;
the BDU module is in communication connection with the main control board through an inter-board communication bus and is used for detecting the working current value of the circuit breaker;
and the second level acquisition circuit is in communication connection with the main control board through an inter-board communication bus and is used for detecting the voltage value of a loop where the circuit breaker is located.
The second part brings the following beneficial effects:
(1) selecting a time period for monitoring through the arrangement of a first data acquisition unit and a second data acquisition unit in a first low-voltage apparatus acquisition board, acquiring coil resistance state data through a third data acquisition unit, and acquiring contact resistance state data through a fourth data acquisition unit; the state data of the circuit breaker is detected through the arrangement of a circuit breaker acquisition module; the main control board calculates the coil resistance value, the contact resistance value, the action time and the action times, filters an invalid tripping event of the breaker and confirms the valid tripping event, and then sends a first low-voltage apparatus fault alarm signal and a breaker tripping alarm signal through the operation and maintenance control module to timely remind operation and maintenance personnel to carry out operation and maintenance, thereby realizing the on-line monitoring and maintenance of the low-voltage apparatus.
(2) And an alternating current excitation source is adopted in the fourth data acquisition unit, compared with a direct current excitation source, the low-voltage direct current excitation source is difficult to superpose when the first low-voltage electrical appliance is conducted, and the high-voltage direct current excitation source easily causes the error output of the high level of a working circuit where the contact is located, so that the safety of the circuit installation of the first low-voltage electrical appliance is influenced, therefore, the feasibility of the on-line monitoring system for the low-voltage electrical appliance is improved through the selection of the alternating current excitation source, and the influence on the normal working circuit of the first low-voltage electrical appliance is reduced.
Drawings
FIG. 1 is a flow chart of a first low-voltage apparatus on-line monitoring method;
FIG. 2 is a flow chart of a second method for online monitoring of a low-voltage apparatus;
FIG. 3 is a logic block diagram of an on-line monitoring system for low-voltage electrical appliances;
FIG. 4 is a schematic diagram of a first low voltage device pickup plate;
fig. 5 is a schematic diagram of a circuit breaker acquisition module.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
Example one
The embodiment provides an online monitoring method for a low-voltage apparatus. The online monitoring method is used for monitoring the low-voltage electrical appliance installed in the whole vehicle system. The low-voltage apparatus comprises a first low-voltage apparatus and a second low-voltage apparatus. The first low-voltage electrical appliance includes at least one of a contactor and a relay. The second low-voltage electrical appliance comprises a circuit breaker. The low-voltage apparatus online monitoring method comprises at least one of a first low-voltage apparatus online monitoring method and a breaker online monitoring method.
As shown in fig. 1, the first low-voltage apparatus online monitoring method includes:
and S01, selecting a time period, wherein the first low-voltage apparatus is conducted in the time period.
And S02, applying an alternating current excitation source to two ends of the contact of the first low-voltage apparatus.
And S03, acquiring contact resistance state data of the first low-voltage electrical appliance.
And S04, disconnecting the two ends of the contact of the first low-voltage apparatus from the alternating current excitation source.
And S05, performing digital filtering on the contact resistance state data. The digital filtering preferably adopts Fourier transform filtering, and after the Fourier transform filtering, contact resistance state data with the same frequency as the alternating current excitation source is obtained.
And S06, calculating the contact resistance value according to the filtered contact resistance state data.
S07, judging whether the contact resistance value is in a first preset range; if yes, jumping to S11; if not, go to S08. Wherein the first preset range is: greater than zero and less than the open circuit resistance of the contact.
And S08, repeatedly executing S02 to S06 to obtain M groups of contact resistance values, wherein each group of contact resistance values comprises N contact resistance values. Wherein S08 includes the following substeps:
and the substep SS01, repeating the steps S02-S06, obtaining N contact resistance values, and marking the N contact resistance values as the same group.
Sub-step SS02, different M-1 time segments are selected.
And the substep SS03, executing S02-S06 in each selected time period to obtain M-1 groups of contact resistance values. Each set of contact resistance values includes N contact resistance values.
And S09, respectively calculating the mean square deviation value of the resistance values of the contacts of each group.
And S10, selecting a group of contact resistance values with the mean square deviation value closest to 0, and calculating the average value of all contact resistance values in the group of contact resistance values.
And S11, judging the running state of the first low-voltage apparatus according to the contact resistance value in the first preset range or the average value of the contact resistance values obtained in the S10.
Preferably, the duration of the time period is greater than the sum of the execution time of S01-S07 and the execution time of SS 01.
Preferably, the following steps are further included between S04 and S05: hardware filtering is performed on the contact resistance state data.
As shown in fig. 2, the second low-voltage apparatus online monitoring method includes:
the method comprises the steps of SSS01, continuously acquiring breaker state data of the breaker, wherein the breaker state data comprise a working current value and working time corresponding to the working current value, and judging whether the working current value is 0; if yes, judging that the circuit breaker is tripped, and executing SSS 02; if not, SSS01 is executed.
And SSS02, calculating the duration that the working current value of the circuit breaker is equal to 0, if the duration is greater than or equal to a first preset period and/or the peak current in n milliseconds before the circuit breaker is tripped is greater than the rated current of the circuit breaker, determining that the circuit breaker tripping event is an effective tripping event, and otherwise, determining that the circuit breaker tripping event is an ineffective tripping event and filtering. The first preset period is preferably 3-5 seconds, and generally, manual closing is started after 3-5 seconds.
Preferably, the circuit breaker state data further includes a circuit voltage value of the circuit breaker, and after confirming that the circuit breaker tripping event is a valid tripping event, the method further includes the following steps:
if the voltage value of the loop where the circuit breaker is located does not fall or the fall value is smaller than the first threshold value in the second preset period, the effective tripping event is re-determined to be an ineffective tripping event and filtered. The second preset period is a time interval between the working time T1 when the working current value of the circuit breaker is a non-zero value and the working time T2 when the working current value of the circuit breaker is 0. Preferably, the operation time T1 is an operation time of a non-zero value selected before the operation current value of the circuit breaker is reduced to 0, and the operation time T2 is an operation time T2 of an operation current value of 0 selected after the operation current value of the circuit breaker is reduced to 0. In some loops where the circuit breaker is located, if an invalid trip event frequently occurs, after the circuit breaker is determined to be the valid trip event in the SSS02, auxiliary judgment is performed through monitoring the voltage value of the loop where the circuit breaker is located, and the accuracy of the trip event monitoring result in the loops is improved.
Preferably, the following fault warning process is further included after step S11, specifically:
and acquiring coil resistance state data of the first low-voltage apparatus.
And calculating the coil resistance value of the first low-voltage apparatus according to the coil resistance state data.
And acquiring coil power-on state data of the first low-voltage apparatus, wherein the coil power-on state data comprises a coil power-on time value.
And acquiring contact closing state data of the first low-voltage apparatus, wherein the contact closing state data comprises a contact closing time value.
And calculating the action time of the first low-voltage electrical apparatus according to the coil power-on state data and the contact closing state data of the first low-voltage electrical apparatus, and accumulating the action times, wherein the action time is the difference between the contact closing time value and the coil power-on time value, and the counting condition of the action times is that the coil is powered on and then the contact closing is counted as one action.
And performing alarm judgment according to the contact resistance value in the first preset range or the average value of the contact resistance values obtained in the S10, the coil resistance value, the action time and the action times, and obtaining a first judgment result.
And if the first judgment result accords with the alarm condition, sending a fault alarm signal. In a general embodiment, the alarm condition includes:
a first alarm condition: the action time is below a second threshold. The pre-judging fault is as follows: coil turn-to-turn short circuit, spring/reed overtravel, or over-strong core magnetic force.
The second alarm condition: the action time is larger than a third threshold value, the resistance value of the contact is within a first preset range, the resistance value of the coil is within a second preset range, the coil is electrified and the contact is closed, wherein the third threshold value is larger than the second threshold value. The pre-judging fault is as follows: the spring is blocked, deformed and rusted or the magnetic force of the iron core is removed.
The third alarm condition: the action time is larger than a third threshold value, the resistance value of the coil is within a second preset range, and the coil is electrified and the contact is not closed. The pre-judging fault is as follows: high impedance is caused by spring or armature breakage, or severe contact wear, or contact oxidation.
A fourth alarm condition: the action time is larger than a third threshold value, the resistance value of the coil is larger than a fourth threshold value, the coil is electrified, and the contact is not closed, wherein the fourth threshold value is larger than the maximum value of a second preset range. The pre-judging fault is as follows: the coil is open-circuited.
Example two
The embodiment provides an online monitoring system for a low-voltage apparatus based on the online monitoring method for the low-voltage apparatus of the first embodiment. As shown in fig. 3, the system includes a power panel, a first low-voltage apparatus acquisition panel, a circuit breaker acquisition module, and a main control panel. The power panel, the first low-voltage electric appliance acquisition panel, the circuit breaker acquisition module and the main control panel are all located at the vehicle-mounted end of the whole vehicle.
A power panel: the circuit breaker acquisition module is used for supplying power to the main control board, the first low-voltage apparatus acquisition board and the circuit breaker acquisition module.
The first low-voltage apparatus acquisition board includes: the device comprises a first data acquisition unit, a second data acquisition unit, a third data acquisition unit, a fourth data acquisition unit and a first MCU control unit.
The first data acquisition unit: and the MCU is used for detecting the coil power-on state data of the first low-voltage apparatus and sending the coil power-on state data to the first MCU.
A second data acquisition unit: the first MCU control unit is used for detecting the contact closing state data of the first low-voltage apparatus and sending the contact closing state data to the first MCU control unit.
A third data acquisition unit: the MCU is used for detecting the coil resistance state data of the first low-voltage apparatus and sending the coil resistance state data to the first MCU control unit.
A fourth data acquisition unit: the first MCU control unit is used for detecting the contact resistance state data of the first low-voltage apparatus and sending the contact resistance state data to the first MCU control unit.
The first MCU control unit: and the third data acquisition unit is connected with the coil of the first low-voltage electrical appliance and the fourth data acquisition unit is connected with the contact of the first low-voltage electrical appliance. The first MCU control unit is also used for sending the coil electrification state data, the contact closing state data, the coil resistance state data and the contact resistance state data to the main control board.
The circuit breaker acquisition module: and detecting the state data of the circuit breaker and sending the state data of the circuit breaker to the main control board.
The main control board:
and calculating the resistance value of the coil, the resistance value of the contact, the action time and the action times according to the power-obtaining state data of the coil, the closing state data of the contact, the resistance state data of the coil and the resistance state data of the contact, and judging the running state of the first low-voltage electric appliance according to the calculated resistance value of the coil, the resistance value of the contact, the action time and the action times.
And filtering out invalid trip events and confirming valid trip events according to the circuit breaker state data.
In a common embodiment, the low-voltage apparatus online monitoring system further comprises a communication board and an operation and maintenance control module. The main control board is in communication connection with the operation and maintenance control module through the communication board, and the operation and maintenance control module is located at the ground end. The operation and maintenance control module is used for receiving the operation state data of the first low-voltage apparatus transmitted by the main control board, sending out a fault alarm signal according to the operation state data of the first low-voltage apparatus, receiving an effective tripping event of the circuit breaker and sending out a tripping alarm signal according to the effective tripping event of the circuit breaker.
As shown in fig. 4, the fourth data acquisition unit includes an ac excitation source, a first electrical isolator, a second electrical isolator, a current acquisition circuit, and a first level acquisition circuit. The positive pole of the alternating current excitation source is connected with the first input end of the current acquisition circuit, the second input end of the current acquisition circuit is connected with the input end of the first electric isolating switch, the output end of the current acquisition circuit is connected with the first acquisition end of the first MCU control unit, the output end of the first electric isolating switch is respectively connected with the first contact end of the first low-voltage electrical appliance and the first input end of the first level acquisition circuit, the second contact end of the first low-voltage electrical appliance is respectively connected with the input end of the second electric isolating switch and the second input end of the first level acquisition circuit, the output end of the second electric isolating switch is connected with the negative pole of the alternating current excitation source, and the output end of the first level acquisition circuit is connected with the second acquisition end of the first MCU control unit. The first MCU control unit outputs a control signal to control the first electrical isolator through a first optical coupler (not shown in the figure)And the first electrical isolating switch preferably adopts a first electrical isolating relay. The first MCU control unit outputs a control signal through a second optical coupler (not shown in the figure) to control the on-off of a second electrical isolating switch, and the second electrical isolating switch preferably adopts a second electrical isolating relay. The first level acquisition circuit comprises an amplifying circuit, a band-pass filter circuit and the like. The main control board receives current data output by the current acquisition circuit and level data output by the first level acquisition circuit, and calculates a contact resistance value R3, wherein the formula is as follows:
where U1 is the voltage value of the level data output by the first level acquisition circuit, and I1 is the current value of the current data output by the current acquisition circuit.
In a general embodiment, the third data acquisition unit comprises a coil resistance excitation acquisition circuit and a third electrical isolation switch. The coil resistance excitation acquisition circuit comprises a direct current excitation source, a divider resistor and the like. And the direct current excitation source applies direct current voltage to two ends of the first low-voltage apparatus coil through the divider resistor, and the on-off of the coil resistance excitation acquisition circuit and the first low-voltage apparatus coil is controlled through the third electrical isolating switch. The first MCU control unit outputs a control signal through a third optocoupler (not shown in the figure) to control the on-off of a third electrical isolating switch, and the third electrical isolating switch preferably adopts a third electrical isolating relay. The acquisition circuit included in the coil resistance excitation acquisition circuit acquires current data of an excitation loop, voltage data at two ends of a coil, voltage data at one end of a divider resistor far away from a direct current excitation source and the like, and transmits the current data, the voltage data or the like to the third acquisition end of the first MCU control unit, and the main control board receives the current data of the excitation loop, the voltage data at two ends of the coil, the voltage data or the like at one end of the divider resistor far away from the direct current excitation source and calculates the resistance value of the coil.
In a common embodiment, as shown in fig. 4, the first data acquisition unit includes a third level acquisition circuit. The first end of the third level acquisition circuit is connected with the upper end of the first low-voltage apparatus coil, the second end of the third level acquisition circuit is connected with the fourth acquisition end of the first MCU control unit, and the power-on state of the coil is monitored through the third level acquisition circuit to obtain the power-on state data of the coil. The second data acquisition unit comprises a fourth level acquisition circuit and a fifth level acquisition circuit. The first end of the fourth level acquisition circuit is connected with the first end of the first low-voltage apparatus contact, the second end of the fourth level acquisition circuit is connected with the fifth acquisition end of the first MCU control unit, the first end of the fifth level acquisition circuit is connected with the second end of the first low-voltage apparatus contact, the second end of the fifth level acquisition circuit is connected with the sixth acquisition end of the first MCU control unit, the closing state of the contact is monitored through the fourth level acquisition circuit and the fifth level acquisition circuit, and contact closing state data are obtained. And the main control board receives the contact closing state data and analyzes the time value T3 when the voltage of 110V exists at the two ends of the contact. The main control board receives the power-on state data of the coil and analyzes a time value T4 when 110V voltage exists at the upper end of the coil. The main control board calculates the action time T of the first low-voltage apparatus according to the time value T3 and the time value T4, wherein T = T3-T4, and accumulates the action times of the first low-voltage apparatus according to the contact closing state data and the coil power-on state data, and the counting rule of the action times is as follows: the coil is electrified, and then the contact is closed, which is counted as one action.
As shown in fig. 5, the breaker acquisition module includes a BDU module and a second level acquisition circuit. The BDU module is a Breaker Detection Unit.
A BDU module: and the circuit breaker is in communication connection with the main control panel through an inter-board communication bus and is used for detecting the working current value of the circuit breaker. A Hall sensor is arranged in the BDU module, and the working current value of the circuit breaker is collected through the Hall sensor.
The second level acquisition circuit: the circuit breaker is in communication connection with the main control board through an inter-board communication bus and used for detecting the voltage value of a circuit where the circuit breaker is located.
The working principle of the embodiment is as follows:
the first MCU control unit monitors the power-on state and the contact closing state of the first low-voltage apparatus coil through the first data acquisition unit and the second data acquisition unit, judges whether a contact closing moment value is in a time period capable of monitoring or not after monitoring that the first low-voltage apparatus coil is powered on and the contact is closed, and starts monitoring if yes. The specific process of monitoring is as follows: the third level acquisition circuit monitors the power-on state of the coil, the fourth level acquisition circuit and the fifth level acquisition circuit monitor the closing state of the contact, the fourth level acquisition circuit acquires the level signal of the first end of the contact, and the fifth level acquisition circuit acquires the level signal of the second end of the contact. The first MCU control unit controls the first electrical isolation relay, the second electrical isolation relay and the third electrical isolation relay to be closed. Then the alternating current excitation source outputs an alternating current excitation signal, and the direct current excitation source outputs a direct current excitation signal. The third data acquisition unit acquires resistance state data of the coil, and the fourth data acquisition unit acquires a current value of the alternating current excitation loop and voltage drops at two ends of the contact. The Hall sensor detects the working current value of the circuit breaker, and the second level acquisition circuit detects the voltage value of a loop where the circuit breaker is located. The main control board calculates a coil resistance value, a contact resistance value, action time and action times of the first low-voltage apparatus, judges whether the first low-voltage apparatus has a fault or not according to the calculated coil resistance value, the calculated contact resistance value, the calculated action time and the calculated action times, filters an invalid trip event according to a circuit breaker working current value and a circuit voltage value where the circuit breaker is located, and confirms the valid trip event. If the first low-voltage apparatus has a fault, the operation and maintenance control module sends out a fault alarm signal of the first low-voltage apparatus, if the circuit breaker has an effective tripping event, the operation and maintenance control module sends out a tripping alarm signal of the circuit breaker, and then operation and maintenance personnel carry out operation and maintenance.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (13)
1. A low-voltage apparatus on-line monitoring method, the said low-voltage apparatus includes the first low-voltage apparatus and second low-voltage apparatus; the described
The first low-voltage electrical appliance comprises at least one of a contactor and a relay; the second low-voltage electrical apparatus comprises a circuit breaker; the low-voltage electric appliance on-line monitoring method comprises at least one of a first low-voltage electric appliance on-line monitoring method and a second low-voltage electric appliance on-line monitoring method; the method for monitoring the first low-voltage electric appliance on line is characterized by comprising the following steps:
s01, selecting a time period within which the first low-voltage apparatus is conducted;
s02, applying an alternating current excitation source to two ends of a contact of the first low-voltage apparatus;
s03, acquiring contact resistance state data of the first low-voltage apparatus;
s04, disconnecting the two ends of the contact of the first low-voltage apparatus from the AC excitation source;
s05, carrying out digital filtering on the contact resistance state data;
s06, calculating the contact resistance value according to the filtered contact resistance state data;
s07, judging whether the contact resistance value is in a first preset range; if yes, jumping to S11; if not, executing S08;
s08, repeatedly executing S02-S06 to obtain M groups of contact resistance values, wherein each group of contact resistance values comprises N contact resistance values;
s09, respectively calculating the mean square difference value of the resistance values of the contacts;
s10, selecting a group of contact resistance values with the mean square deviation value closest to 0, and calculating the average value of all contact resistance values in the group of contact resistance values;
and S11, judging the running state of the first low-voltage apparatus according to the contact resistance value in the first preset range or the average value of the contact resistance values obtained in the S10.
2. The on-line monitoring method for the low-voltage apparatus according to claim 1, wherein the digital filtering in S05 is fourier transform filtering, and the contact resistance state data having the same frequency as the ac excitation source is obtained through the fourier transform filtering.
3. The on-line monitoring method for the low-voltage apparatus according to claim 1, wherein the step S08 comprises the following substeps:
SS01, repeatedly executing S02-S06 to obtain N contact resistance values which are marked as the same group;
SS02, selecting different M-1 time periods;
and SS03, executing S02-S06 in each selected time period to obtain M-1 groups of contact resistance values, wherein each group of contact resistance values comprises N contact resistance values.
4. The on-line monitoring method for the low-voltage apparatus of claim 3, wherein the duration of the time period in S01 is greater than the sum of the execution time of S01 to S07 and the execution time of SS 01.
5. The on-line monitoring method for the low-voltage apparatus of claim 1, wherein the method between S04 and S05 further comprises the following steps: hardware filtering is performed on the contact resistance state data.
6. The on-line monitoring method for the low-voltage electric appliances according to claim 1, characterized in that the second on-line monitoring method for the low-voltage electric appliances comprises the following steps:
the method comprises the steps of SSS01, continuously acquiring breaker state data of the breaker, wherein the breaker state data comprise a working current value and working time corresponding to the working current value, and judging whether the working current value is 0; if yes, determining that the circuit breaker is tripped, and executing SSS 02; if not, SSS01 is executed;
and SSS02, calculating the duration that the working current value of the circuit breaker is equal to 0, if the duration is greater than or equal to a first preset period and/or the peak current in n milliseconds before the circuit breaker is tripped is greater than the rated current of the circuit breaker, determining that the circuit breaker tripping event is an effective tripping event, and otherwise, determining that the circuit breaker tripping event is an ineffective tripping event and filtering.
7. The on-line monitoring method for the low-voltage apparatus according to claim 6, wherein the breaker state data further comprises a circuit voltage value of the breaker; the method also comprises the following steps after confirming that the circuit breaker tripping event is an effective tripping event:
if the voltage value of a loop where the circuit breaker is located does not fall or the fall value is smaller than the first threshold value in the second preset period, re-determining the effective trip event as an ineffective trip event and filtering the ineffective trip event;
the second preset period is a time interval between a working time T1 when the working current value of the circuit breaker is a non-zero value and a working time T2 when the working current value of the circuit breaker is 0.
8. The on-line monitoring method for the low-voltage apparatus according to claim 7, wherein the step of after S11 is further included:
acquiring coil resistance state data of a first low-voltage apparatus;
calculating the coil resistance value of the first low-voltage electrical apparatus according to the coil resistance state data;
acquiring coil power-on state data of a first low-voltage electrical appliance, wherein the coil power-on state data comprises a coil power-on time value;
acquiring contact closing state data of a first low-voltage apparatus, wherein the contact closing state data comprises a contact closing time value;
calculating the action time of the first low-voltage electrical apparatus according to the coil power-on state data and the contact closing state data of the first low-voltage electrical apparatus and accumulating the action times, wherein the action time is the difference between the contact closing time value and the coil power-on time value, and the counting condition of the action times is that the coil is powered on and then the contact is closed and counted as one action;
performing alarm judgment according to the contact resistance value in the first preset range or the average value of the contact resistance values obtained in S10, the coil resistance value, the action time and the action times, and obtaining a first judgment result;
and if the first judgment result accords with the alarm condition, sending a fault alarm signal.
9. The low-voltage apparatus on-line monitoring system based on the low-voltage apparatus on-line monitoring method of claim 8 is characterized by comprising a power panel, a first low-voltage apparatus acquisition panel and a main control panel;
the power panel is used for supplying power to the main control panel and the first low-voltage electrical apparatus acquisition panel;
the first low-voltage electric appliance acquisition board comprises a first data acquisition unit, a second data acquisition unit, a third data acquisition unit, a fourth data acquisition unit and a first MCU (microprogrammed control Unit);
the first data acquisition unit is used for detecting the coil power-on state data of the first low-voltage apparatus and sending the coil power-on state data to the first MCU;
the second data acquisition unit is used for detecting contact closing state data of the first low-voltage apparatus and sending the contact closing state data to the first MCU control unit;
the third data acquisition unit is used for detecting coil resistance state data of the first low-voltage apparatus and sending the coil resistance state data to the first MCU control unit;
the fourth data acquisition unit is used for detecting contact resistance state data of the first low-voltage apparatus and sending the contact resistance state data to the first MCU control unit;
the first MCU control unit is used for judging whether the coil of the first low-voltage electrical appliance is electrified or not and whether the contact is closed or not according to the coil electrification state data and the contact closing state data, and if the coil electrification, the contact closing and the contact closing time value are within any one time period, the connection between the third data acquisition unit and the coil of the first low-voltage electrical appliance is connected, and the connection between the fourth data acquisition unit and the contact of the first low-voltage electrical appliance is connected;
the first MCU control unit is also used for sending the coil power-on state data, the contact closing state data, the coil resistance state data and the contact resistance state data to the main control board;
the main control board calculates a coil resistance value, a contact resistance value, action time and action times according to the coil power-on state data, the contact closing state data, the coil resistance state data and the contact resistance state data, and judges the running state of the first low-voltage electric appliance according to the coil resistance value, the contact resistance value, the action time and the action times.
10. The on-line monitoring system for the low-voltage electric appliances according to claim 9, further comprising a circuit breaker acquisition module, wherein the power panel is further used for supplying power to the circuit breaker acquisition module; the circuit breaker acquisition module is used for detecting circuit breaker state data and sending the circuit breaker state data to the main control board, and the main control board filters invalid tripping event and confirms valid tripping event according to the circuit breaker state data.
11. The on-line monitoring system for the low-voltage electric appliances according to claim 10, characterized by further comprising an operation and maintenance control module and a communication board; the main control board is in communication connection with the operation and maintenance control module through a communication board; the operation and maintenance control module is used for receiving the operation state data of the first low-voltage apparatus transmitted by the main control board and sending out a fault alarm signal according to the operation state data of the first low-voltage apparatus; the operation and maintenance control module is also used for receiving the effective tripping event of the circuit breaker transmitted by the main control panel and sending a tripping alarm signal according to the effective tripping event of the circuit breaker.
12. The on-line monitoring system for the low-voltage apparatus according to claim 9, wherein the fourth data acquisition unit comprises an alternating current excitation source, a first electrical isolating switch, a second electrical isolating switch, a current acquisition circuit and a first level acquisition circuit; the positive pole of the alternating current excitation source is connected with the first input end of the current acquisition circuit, the second input end of the current acquisition circuit is connected with the input end of the first electric isolating switch, the output end of the current acquisition circuit is connected with the first acquisition end of the first MCU control unit, the output end of the first electric isolating switch is respectively connected with the first contact end of the first low-voltage electric appliance and the first input end of the first level acquisition circuit, the second contact end of the first low-voltage electric appliance is respectively connected with the input end of the second electric isolating switch and the second input end of the first level acquisition circuit, the output end of the second electric isolating switch is connected with the negative pole of the alternating current excitation source, and the output end of the first level acquisition circuit is connected with the second acquisition end of the first MCU control unit; the first MCU control unit is also used for controlling the first electrical isolating switch and the second electrical isolating switch to be switched on or switched off.
13. The on-line monitoring system for the low-voltage apparatus according to claim 10, wherein the breaker acquisition module comprises a BDU module and a second level acquisition circuit;
the BDU module is in communication connection with the main control board through an inter-board communication bus and is used for detecting the working current value of the circuit breaker;
and the second level acquisition circuit is in communication connection with the main control board through an inter-board communication bus and is used for detecting the voltage value of a loop where the circuit breaker is located.
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