CN114583660A

CN114583660A - Motor relay protection device and method for belt conveyor scratch fault protection

Info

Publication number: CN114583660A
Application number: CN202111484854.8A
Authority: CN
Inventors: 张洁; 邓先鹍; 丁宁; 皋德华
Original assignee: Jiangsu Sheyanggang Power Generation Co ltd; Wiscom System Co ltd
Current assignee: Jiangsu Sheyanggang Power Generation Co ltd; Wiscom System Co ltd
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2022-06-03
Anticipated expiration: 2041-12-07
Also published as: CN114583660B

Abstract

The invention discloses a motor relay protection device and a motor relay protection method for belt conveyor scratch fault protection, and the motor relay protection device comprises an alternating current acquisition unit, a switching value input unit, a switching value output unit, a processing unit and a current transformer, wherein the current transformer is used for being arranged on a connecting lead between a power bus and a motor; the alternating current flow acquisition unit, the switching value input unit and the switching value output unit are connected with the processing unit, the alternating current flow acquisition unit is connected with the current transformer, the receiving end of the switching value input unit is connected with the circuit breaker, and the sending end of the switching value output unit is connected with the circuit breaker. The belt scratch fault detection device can detect the scratch fault of the belt in real time, send out an alarm or automatically trip in time to prevent the accident from being serious, effectively reduce the scratch fault rate of the belt conveyor and improve the economic benefit of a power plant.

Description

Motor relay protection device and method for belt conveyor scratch fault protection

Technical Field

The invention belongs to the technical field of relay protection of power systems, and can realize functions of early warning of scratch faults of belt conveyors of power plants and trip protection in a motor relay protection device.

Background

The belt conveyer is commonly called as belt conveyer, and is an important transportation equipment of coal conveying system in thermal power plant, and it uses motor as drive, and then uses the components of tensioning and changing direction to form a closed-loop belt which can be uniformly rotated, and uses static friction force to drive the object on the belt to make uniform motion so as to attain the goal of conveying material. The belt accounts for more than 40% of the cost of the whole conveyor, and the belt is a weak link easy to damage, so that the belt is protected to be damaged to the minimum degree, and the belt monitoring device has important significance for maintaining the safe operation of a power plant. The sharp iron sundries or sharp large rock blocks in the conveyed materials cause the belt to be scratched or even torn when falling, and the belt is the most common damage fault type. The scratch of the belt affects the normal supply of the fuel quantity of the boiler, and the scratch of the belt affects the load forced to drop or limits the electricity to the outside when the scratch of the belt is heavy, thereby causing huge economic loss. In recent years, various belt fault diagnosis devices are researched and designed at home and abroad, and embedded embedding detection devices, ultrasonic flaw detection and other modes are adopted, but the belt fault diagnosis devices have the problems of being not mature enough, complex in operation and maintenance, needing to increase investment and the like. At present, many power plants in China are not provided with effective belt scratch detection devices, and hidden dangers are brought to the safe operation of the power plants.

The motor in the belt feeder all can dispose motor relay protection device as power plant electrical system's important load, and electric volume such as galvanic pressure is gathered to the device, is equipped with and overflows, overload, locked rotor, open phase, overheated, protection logics such as start-up time overlength, and various common fault angles monitor the motor to in time make the early warning or cut off the trouble. The belt is a specific load of the motor, and when a foreign object scratch problem occurs, the electric quantity on the stator side of the motor fluctuates somewhat, but the change characteristics do not necessarily satisfy the logic conditions of the conventional motor protection. For example, when a belt is scratched by an instant sharp object, the current suddenly increases for a short time, but the current amplitude and the duration time do not necessarily reach the threshold of the overcurrent and overload protection constant value, so that the protection cannot act; or the belt is blocked by foreign matters to prevent the belt from running, and at the moment, the motor still rotates and is not locked, so that the locked-rotor protection cannot be operated; or when the belt is scratched, the current is increased, but the material on the belt is less, and the current is close to or lower than the rated current of the motor, so that the conventional protection logic can not be started, and the belt is easy to damage after being continuously operated for a long time. It is a significant problem to implement identification and monitoring of belt scratch failures in conventional protective devices.

Disclosure of Invention

The purpose of the invention is as follows: in the conventional motor relay protection device, the functions of alarming belt scratch faults and protecting tripping are realized according to the characteristics of the electric quantity of a motor when the belt scratch faults.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:

the utility model provides a motor relay protection device for belt feeder fish tail fault protection, includes interchange volume acquisition unit, switching value input unit, switching value output unit, processing unit and current transformer, wherein:

the current transformer is used for being installed on a connecting wire between a circuit breaker of the motor and a power bus.

The receiving end of the alternating current quantity acquisition unit is used for being connected with the current transformer, and the sending end of the alternating current quantity acquisition unit is connected with the processing unit.

The receiving end of the switching value input unit is connected with the circuit breaker, and the transmitting end of the switching value input unit is connected with the processing unit.

And the receiving end of the switching value output unit is connected with the processing unit, and the transmitting end of the switching value output unit is connected with the circuit breaker.

Preferably: the alternating current capacity acquisition unit comprises a voltage transformer, wherein the voltage transformer is arranged on a connecting wire between a circuit breaker and a power bus, and a receiving end of the alternating current capacity acquisition unit is used for being connected with the voltage transformer.

Preferably: the display communication unit is connected with the processing unit.

Preferably: the alarm device comprises an alarm prompting unit, wherein the alarm prompting unit is connected with a switching value output unit.

Preferably: the processing unit is a single chip microcomputer.

Preferably: the processing unit comprises a current extraction module, a first three cycle phase current average amplitude extraction module, a motor running state judgment module, a current sudden increase judgment module, an overcurrent judgment module and a first OR circuit, wherein: the current extraction module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current running state judgment module, the current surge judgment module and the overcurrent judgment module, the current running state judgment module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current surge judgment module and the overcurrent judgment module, and the current surge judgment module and the overcurrent judgment module are connected with the first OR circuit.

Preferably: the current extraction module is used for extracting three-phase current according to the collected current electric quantity. Determining to calculate each phase current amplitude I in real time according to the extracted three-phase current_phAnd three-phase maximum current value I_max。

The first three cycle phase current average amplitude extraction module is used for memorizing six current amplitudes by taking a half cycle as an interval, and obtaining the current real-time first three cycle phase current average amplitudes at each sampling moment

The motor running state judging module comprises a first closing position judging circuit, a first motor running state comparing circuit, a first motor running state and circuit and a second motor running state and circuit, wherein the first closing position judging circuit is used for judging whether the position of a circuit breaker of the motor is in a closing position or not and sending closing position information of the circuit breaker to the circuit breakerAnd sending the running state and the circuit of the first motor. The first motor running state comparison circuit is used for comparing a three-phase maximum current value I_maxComparing with the light load current high limit value and the light load current low limit value, if the three-phase maximum current value I_maxAnd when the current is between the light-load current high limit value and the light-load current low limit value, outputting a first comparison signal to the first motor running state and circuit. If the three-phase maximum current value I_maxAnd if the current is larger than the light-load current high limit value, outputting a second comparison signal to the running state and the circuit of the second motor. The first motor running state and circuit obtains a motor light-load running interval signal according to the on-position information and the first comparison signal, and sends the motor light-load running interval signal to the current sudden increase judging module. And the second motor running state and circuit performs AND operation according to the on-position information and the second comparison signal to obtain a signal of the motor in a normal running interval, and sends the signal of the motor in the normal running interval to the overcurrent judging module.

Preferably: the current surge judging module comprises a starting surge sub-module, a phase current surge value calculating circuit, a first current surge comparing circuit, a first current surge timer, a second current surge comparing circuit, a first timing comparing circuit and a first current surge and circuit.

The starting sudden increase sub-module starts a phase current sudden increase value calculation circuit, a first current sudden increase comparison circuit, a first current sudden increase timer, a second current sudden increase comparison circuit, a first timing comparison circuit and a first current sudden increase and circuit according to the light load operation interval signal sent by the motor operation state judging module.

The first phase current sudden increase value calculation circuit is used for calculating the amplitude value I of each phase current_phTaking a model after the difference between the current real-time average amplitude of the current of the first three cycles and the current of the first three cycles to obtain the sudden increase value of the first phase current,

the first current sudden increase comparison circuit is used for comparing the first phase current sudden increase value with the phase current sudden increase set value, and if the first phase current sudden increase value is larger than the phase current sudden increase set value, the current real-time previous three cycle phase current average amplitude values when the first phase current sudden increase value is met for the first time are compared

To memorize the value

And starting a first current surge timer for timing to obtain a current surge timing t 1.

The second phase current abrupt value calculation circuit is used for calculating the amplitude I of each phase current_phAnd memorize the value

And obtaining the second phase current abrupt value by taking the modulus after the difference is made.

The second current surge comparison circuit compares the second-phase current surge value with the phase current surge set value, if the second-phase current surge value is larger than the phase current surge set value, a current surge comparison signal is obtained, and the current surge comparison signal is sent to the first current surge and circuit.

The first timing comparison circuit is used for comparing the current surge timing t1 with the phase current surge delay time, and if the current surge timing t1 is greater than the phase current surge delay time, a current surge delay signal is sent to the first current surge and circuit.

The first current surge and circuit is used for conducting and operation according to the current surge comparison signal and the current surge delay signal, if the current surge comparison signal and the current surge delay signal are true at the same time, it is indicated that a phase current surge criterion is met, and a phase current surge criterion signal meeting the light-load operation interval is sent to the first or circuit.

The over-current judging module comprises a start judging submodule, a current continuous over-limit judging submodule, a current out-of-limit accumulated times over-limit judging submodule and an over-current judging or circuit

The starting judgment sub-module starts a current continuous out-of-limit judgment sub-module, a current out-of-limit accumulated times out-of-limit judgment sub-module and an over-current judgment or circuit according to the conventional operation interval signal sent by the motor operation state judgment module.

The current continuous overrun judging submodule comprises a current continuous overrun comparison circuit, a current continuous overrun timer and a current continuous time overrun comparison circuit,

the current continuous overrun comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the current continuously out-of-limit current set value, and if the three-phase maximum current value I_maxIf the current value is larger than the current continuous out-of-limit set value, a current continuous out-of-limit timer is started to time, and the current continuous out-of-limit time t2 is obtained.

The current duration time overrun comparison circuit is used for comparing the current duration overrun timing t2 with a current duration overrun time set value, if the current duration overrun timing t2 is larger than the current duration overrun time set value, the current duration overrun criterion meeting the overcurrent in the normal operation interval is represented, and a current duration overrun signal of the overcurrent in the normal operation interval is sent to the overcurrent judgment or circuit.

The current out-of-limit accumulated time overrun judging submodule comprises a current out-of-limit accumulated time comparing circuit, a current out-of-limit accumulated time timer, a first current out-of-limit accumulated time comparing circuit, a second current out-of-limit accumulated time comparing circuit and a current out-of-limit accumulated time and circuit.

The current out-of-limit accumulated times comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the current out-of-limit accumulated times and current set value, and determining the maximum current value I of three phases_maxIf the current value is larger than the current out-of-limit accumulated times and exceeds the current set value, starting a current out-of-limit accumulated times timer to time to obtain current out-of-limit accumulated times timing t3, and counting the three-phase maximum current value I_maxAnd the number n is larger than the number of times that the current out-of-limit accumulated number exceeds the set value of the current.

The first current out-of-limit accumulated time comparison circuit is used for comparing the current out-of-limit accumulated time t3 with an accumulated time window set value, and if the current out-of-limit accumulated time t3 is smaller than the accumulated time window set value, sending a current out-of-limit accumulated time smaller than a signal to the current out-of-limit accumulated time comparison circuit.

The second currentOut-of-limit accumulated times comparison circuit for three-phase maximum current value I_maxThe number n of times of the current set value exceeding the current out-of-limit accumulated number is compared with the accumulated out-of-limit set value, and if the three-phase maximum current value I is larger than the accumulated out-of-limit accumulated number, the three-phase maximum current value I is detected_maxAnd the number n of times of exceeding the current set value and the current out-of-limit accumulated number is greater than the accumulated out-of-limit number set value of the accumulated time window set value, and the current out-of-limit accumulated number is sent to a current out-of-limit accumulated number and circuit.

The current out-of-limit accumulated times and circuit counts and calculates according to the fact that the current out-of-limit accumulated times is smaller than the signal in timing and the current out-of-limit accumulated times is larger than the signal, if the fact that the current out-of-limit accumulated times is smaller than the signal and the current out-of-limit accumulated times is larger than the signal is true at the same time, the current out-of-limit accumulated times out-of-limit criterion which meets the overcurrent in the normal operation interval is represented, and the current out-of-limit accumulated times out-of-limit signal of the overcurrent in the normal operation interval is sent to the overcurrent judgment or circuit.

The overcurrent judging or circuit carries out or calculates according to the overcurrent continuous overrun signal in the normal operation interval and the overcurrent out-of-limit accumulated frequency overrun signal in the normal operation interval, if one of the overcurrent continuous overrun signal in the normal operation interval and the overcurrent out-of-limit accumulated frequency overrun signal in the normal operation interval is true, the overcurrent judging or circuit indicates that the overcurrent judging or circuit in the normal operation interval is met, and the overcurrent judging or circuit sends the overcurrent judging or circuit signal in the normal operation interval to the first or circuit.

The first OR circuit is used for carrying out OR calculation according to the phase current surge criterion signal meeting the normal operation interval and the overcurrent criterion signal meeting the normal operation interval, if one of the phase current surge criterion signal meeting the normal operation interval and the overcurrent criterion signal meeting the normal operation interval is true, the belt conveyor scratch fault is judged, and the first OR circuit sends a fault signal to the switching value output unit. The switching value output unit transmits a fault signal to the circuit breaker, and the circuit breaker performs a trip operation.

A motor relay protection method for protecting scratch faults of a belt conveyor comprises the following steps:

step S1, collecting electricityThree phase current values and breaker positions when the motor is running. Calculating the amplitude I of each phase current in real time_phAnd three-phase maximum current value I_maxWherein, I_phFor the current real-time phase current magnitude, ph A, B, C is the phase difference, I_maxIs the maximum value of the three-phase current.

Step S2, memorizing current amplitude for six times with half cycle as interval, calculating current real-time previous three cycle current average amplitude at each sampling time

ph is A, B, C, and T represents the period.

Step S3, passing three-phase maximum current value I_maxAnd the circuit breaker position judgment currently determines whether the motor is in a light-load operation zone or a normal operation zone. If the motor is in the light-load operation zone, the process proceeds to step S4. If the motor is in the normal operation zone, the process goes to step S6.

Step S4, real-time judging whether the requirement is satisfied

When the current average amplitude value is met for the first time, the current average amplitude value of the current phase current of the first three real-time cycles is recorded

To memorize the value

And starting a timer to obtain a current surge time t1, wherein I_set3Is a phase current surge set value.

Step S5, judging whether the requirements are met in real time

And T1 > T_set1If yes, the phase current sudden increase criterion is met, and the step S8 is skipped, wherein T_set1Delay time is suddenly increased for the phase current.

And step S6, executing overcurrent criteria in the normal operation interval, including a current continuous overrun criterion of overcurrent in the normal operation interval and a current overrun accumulated times overrun criterion of overcurrent in the normal operation interval.

Step S61, determining the overcurrent continuous overrun criterion in the normal operation interval: real-time judgment whether I is satisfied_max＞I_set4And T2 > T_set2. If yes, the current continuous overrun criterion of overcurrent in the normal operation interval is met, and the step goes to step S7, wherein I_set4For the current continuously exceeding the current set value, T_set2The current duration overrun time setting value is t2, the current duration overrun time is t2 is the initial I_max＞I_set4When the timer is satisfied, the timer starts to count.

Step S62, the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval is as follows: real-time judgment of whether I is satisfied_max＞I_set5，t3<T_set3And N > N_set. If yes, meeting the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval, and jumping to the step S7, wherein I_set5For the current out-of-limit accumulated times exceeding the current set value, T_set3For accumulating the time window set value, N_setIs a setting value for accumulating the number of times of exceeding the limit. t3 is I_max＞I_set5A timer started after the first time is met, n is I in t3_max＞I_set5The number of times satisfied. When N > N_setOr T3 > T_set3Thereafter, n and t3 are cleared to avoid running into the running total.

Step S7, overcurrent criterion of normal operation interval: and if the current continuous overrun criterion of the overcurrent in the normal operation interval is met or the current overrun accumulated number overrun criterion of the overcurrent in the normal operation interval is met, meeting the overcurrent criterion in the normal operation interval, and jumping to the step S8.

And step S8, meeting the phase current sudden increase criterion in the light-load operation interval or the overcurrent criterion in the normal operation interval, judging that the belt conveyor is scratched to cause a fault, outputting the fault to a switching value output unit, and sending out automatic tripping.

Preferably: passing the three-phase maximum current value I in step S3_maxAnd circuit breaker position determinationThe current method is that the motor is in a light-load operation zone or a normal operation zone:

if the circuit breaker of the motor is in the closed position and I_set2＞I_max＞I_setThe motor is in a light-load operation interval, wherein I_setFor a high limit of light-load current, I_setThe light load current lower limit value.

If the circuit breaker of the motor is in the closed position and I_max＞I_set2The motor is in the normal operation zone.

Compared with the prior art, the invention has the following beneficial effects:

the device adopts the mode that the belt conveyor scratch protection is additionally arranged on the basis of the relay protection device of the existing belt conveyor motor, the belt scratch fault is detected in real time, and the alarm or automatic trip and outage are timely sent out to prevent the accident from being serious. The belt conveyor has the advantages that investment is not increased, the belt is not damaged, the complexity of operation and maintenance is not increased, the scratch failure rate of the belt conveyor is effectively reduced, the economic benefit of a power plant is improved, and the belt conveyor has high engineering practical value.

Drawings

FIG. 1 is a block diagram of the embodiment

The device comprises a 1-alternating current acquisition unit, a 2-switching value input unit, a 3-switching value output unit, a 4-processing unit, a 5-display communication unit, a 6-voltage transformer, a 7-current transformer, an 8-circuit breaker, a 9-alarm indication unit, a 10-motor and an 11-belt.

Detailed Description

The present invention is further illustrated in the accompanying drawings and described in the following detailed description, it is to be understood that such examples are included solely for the purposes of illustration and are not intended as a definition of the limits of the invention, since various equivalent modifications of the invention will become apparent to those skilled in the art after reading the present specification, and it is intended to cover all such modifications as fall within the scope of the invention as defined in the appended claims.

A motor relay protection method for protecting a belt conveyor from a scratch fault is shown in figure 1, and the characteristics that a current increment suddenly changes when a belt is scratched, the current is recovered after being increased for several times and instantly, and the current is continuously increased are found by analyzing the running current of a motor when the belt conveyor has the scratch fault. When the motor is in light load, the running current of the motor is small, the device cannot directly judge the scratch fault according to the current, and a current increment mutation method is adopted for judging; the belt scratch trouble when normal load, then the discernment of accessible electric current amplitude size specifically includes the following steps:

step S1, three-phase current values and the position of the breaker 8 when the motor 10 is operating are collected. Calculating the amplitude I of each phase current in real time_phAnd three-phase maximum current value I_maxWherein, I_phFor the current real-time phase current magnitude, ph A, B, C is the phase difference, I_maxIs the maximum value of the three-phase current.

ph is A, B, C, and T represents the period.

Step S3, passing three-phase maximum current value I_maxAnd the circuit breaker 8 position determination is currently whether the motor 10 is in a light-load operating zone or a normal operating zone. If the motor 10 is in the light-load operation zone, the process proceeds to step S4. If the motor 10 is in the normal operation zone, the process proceeds to step S6.

Passing the three-phase maximum current value I in step S3_maxAnd the method for judging the position of the breaker 8 that the motor 10 is in the light-load operation zone or the normal operation zone at present:

if the circuit breaker 8 of the motor 10 is in the closed position and I_set2＞I_max＞I_set1The motor 10 is in a light-load operation region, wherein I_set2For a high limit of light-load current, I_set1The light load current lower limit value.

If the circuit breaker 8 of the motor 10 is in the closed position and I_max＞I_set2The motor 10 is in the normal operation zone.

Step S4, executing the criterion of sudden increase of phase current in the light-load operation interval: real-time judgment whether the requirements are met

To memorize the value

Step S5, executing the criterion of sudden increase of phase current in the light-load operation interval: real-time judgment whether the requirements are met

And T1 > T_set1If yes, indicating that the phase current surge criterion is met, jumping to step S8, wherein T_set1Delay time is suddenly increased for the phase current.

Step S6, executing a normal operation interval overcurrent criterion: the method comprises a current continuous out-of-limit criterion of overcurrent in a normal operation interval and an out-of-limit criterion of current out-of-limit accumulated times of overcurrent in the normal operation interval.

Step S61, determining the overcurrent continuous overrun criterion in the normal operation interval: real-time judgment whether I is satisfied_max＞I_set4And T2 > T_set2. If yes, the current continuous overrun criterion of overcurrent in the normal operation interval is met, and the operation goes to step S7, wherein I_set4For the current continuously exceeding the current set value, T_set2The current duration overrun time setting value is t2, the current duration overrun time is t2 is the initial I_max＞I_set4When the timer is satisfied, the timer starts to count.

Step S62, the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval is as follows: real-time judgment of whether I is satisfied_max＞I_set5，t3＜T_set3And N > N_set. If yes, meeting the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval, and jumping to the step S7, wherein I_set5For the current out-of-limit accumulated times exceeding the current set value, T_set3For accumulating the time window set value, N_setIs a setting value for accumulating the number of times of exceeding the limit. t3 is I_max＞I_set5A timer started after the first time is met, n is I in t3_max＞I_set5The number of times satisfied. When N > N_setOr T3 > T_set3Thereafter, n and t3 are cleared to avoid running into the running total.

And step S8, meeting the phase current sudden increase criterion in the light-load operation interval or the overcurrent criterion in the normal operation interval, judging that the belt conveyor is scratched to cause a fault, outputting the fault to the switching value output unit 3, and sending out automatic tripping.

The utility model provides a motor relay protection device for belt feeder fish tail fault protection, as shown in fig. 1, includes that volume of handing over gathers unit 1, switching value input unit 2, switching value output unit 3, processing unit 4, display communication unit 5, voltage transformer 6, current transformer 7, warning suggestion unit 9, wherein:

the circuit breaker 8 is mounted on the connecting conductor between the power bus and the motor 10.

And the voltage transformer 6 and the current transformer 7 are arranged on a connecting wire between the circuit breaker 8 and the power bus.

The receiving end of the alternating current quantity acquisition unit 1 is used for being connected with a voltage transformer 6 and a current transformer 7, and the sending end of the alternating current quantity acquisition unit 1 is connected with the processing unit 4. The alternating current acquisition unit 1 is used for acquiring current and voltage electrical quantity signals output by a current transformer 7 and a voltage transformer 6 when a motor 10 in the belt conveyor runs, conditioning and converting the current and voltage electrical quantity signals into digital analog quantity signals, and inputting the current and voltage electrical quantity signals converted into the digital analog quantity signals into the processing unit 4 through an internal data bus.

The receiving end of the switching value input unit 2 is connected to the circuit breaker 8, and the transmitting end of the switching value input unit 2 is connected to the processing unit 4. The switching value input unit 2 is configured to acquire a strong hard-wired signal of the position of the circuit breaker 8, convert the strong hard-wired signal into a digital state quantity signal through photoelectric isolation, and input the strong hard-wired signal converted into the digital state quantity signal to the processing unit 4 through an internal I0 bus.

The receiving end of the switching value output unit 3 is connected to the processing unit 4, and the transmitting end of the switching value output unit 3 is connected to the circuit breaker 8.

The display communication unit 5 is connected to the processing unit 4. The display communication unit 5 realizes information interaction between the device and local users and information uploading and issuing. The switching value output unit 3 is used for receiving the fault digital control signal sent by the processing unit 4, so as to drive the on-off of the relay in the switching value output unit 3 and send the signal to the operation circuit of the circuit breaker 8, thereby realizing the tripping control of the circuit breaker 8 of the motor 10. The switching value output unit 3 converts the fault digital control signal into a switching signal of a relay and sends the switching signal to the alarm prompting unit 9, so that the control of equipment such as an indicator lamp, a buzzer and the like in the field alarm prompting unit 9 is realized. And the alarm prompt unit 9 carries out alarm prompt according to the control signal of the fault relay.

The processing unit 4 is the core of the whole device, extracts features from the alternating current electrical quantity of the motor 10 collected by the alternating current quantity collecting unit 1, performs auxiliary judgment by combining position signals of the circuit breaker 8 input by the switching quantity input unit 2, and distinguishes that when the belt 11 driven by the motor 10 has a scratch fault, the switching quantity output unit 3 acts on an external alarm 9 and a tripping loop of the circuit breaker 8, and reminds an operator to check through the alarm indicating unit 9 or automatically jumps to stop the driving motor 10 of the belt conveyor through the circuit breaker 8, so that the damage time of the belt 11 is shortened, and the damage severity is reduced.

The running current analysis of the motor when the belt conveyor has a scratch fault discovers that the current increment mutation can occur when the belt is scratched, the current is recovered after being increased for a moment, the current is continuously increased and the like. When the motor is in light load, the running current of the motor is small, the device cannot directly judge the scratch fault according to the current, and a current increment mutation method is adopted for judging; and the belt scratch fault under normal load can be identified through the change of the current amplitude.

Collecting three-phase current values when the motor 11 runs; calculating the amplitude of each phase current and the maximum current of three phases in real time; judging whether the motor is in a light-load operation zone or a conventional operation zone at present by combining the maximum current and a motor starting button; if the belt conveyor is in the light-load operation interval, identifying that the belt conveyor is in a scratch state through phase current sudden increase criteria; and if the motor is in the normal operation interval, identifying that the motor is in a scratch state through an overcurrent criterion. And after the judgment is finished, an alarm is sent to prompt an operator to handle, or tripping is sent to shorten the damage time of the belt, so that the damage severity is reduced.

When the single chip microcomputer is realized, the method is loaded in the single chip microcomputer through programming to form a processing unit 4.

When the circuit is implemented, the processing unit 4 includes a current extraction module, a previous three cycle phase current average amplitude extraction module, a motor running state determination module, a current sudden increase determination module, an overcurrent determination module, and a first or circuit, wherein: the current extraction module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current running state judgment module, the current surge judgment module and the overcurrent judgment module, the current running state judgment module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current surge judgment module and the overcurrent judgment module, and the current surge judgment module and the overcurrent judgment module are connected with the first OR circuit.

The current extraction module is used for extracting three-phase current according to the collected current electric quantity. Determining to calculate each phase current amplitude value in real time according to the extracted three-phase currentI_phAnd three-phase maximum current value I_max。

The motor running state judging module comprises a first closing position judging circuit, a first motor running state comparing circuit, a first motor running state and circuit and a second motor running state and circuit, wherein the first closing position judging circuit is used for judging whether the position of a circuit breaker 8 of the motor 10 is in a closing position or not and sending closing position information of the circuit breaker 8 to the first motor running state and circuit. The first motor running state comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the light load current high limit value and the light load current low limit value, and if the three-phase maximum current value I_maxAnd when the current is between the light-load current high limit value and the light-load current low limit value, outputting a first comparison signal to the first motor running state and circuit. If the three-phase maximum current value I_maxAnd if the current is larger than the light-load current high limit value, outputting a second comparison signal to the running state and the circuit of the second motor. The first motor running state and circuit obtains a motor light-load running interval signal according to the on-position information and the first comparison signal, and sends the motor light-load running interval signal to the current sudden increase judging module. And the second motor running state and circuit performs AND operation according to the on-position information and the second comparison signal to obtain a signal of the motor in a normal running interval, and sends the signal of the motor in the normal running interval to the overcurrent judging module.

The current surge judging module comprises a phase current surge value calculating circuit, a first current surge comparing circuit, a first current surge timer, a second current surge comparing circuit, a first timing comparing circuit and a first current surge and circuit.

The first phase current sudden increase value calculation circuit is used for calculating the amplitude value I of each phase current_phAnd the calculation circuit comprises an adder and a modulus extractor, and the adder is used for subtracting the average amplitude of the current of the first three periodic waves and then performing modulus extraction to obtain the sudden increase value of the first phase current_phAnd the current real-time average amplitude of the phase current of the first three cycles is inverted and added to realize calculation, and the modulus of the calculated value is obtained through a modulus obtaining device, so that the output is guaranteed to be a positive value.

To memorize the value

The first current surge and circuit is used for carrying out AND operation according to the current surge comparison signal and the current surge delay signal, if the current surge comparison signal and the current surge delay signal are true at the same time, the phase current surge criterion is met, and a phase current surge criterion signal meeting the light-load operation interval is sent to the first OR circuit.

The current out-of-limit accumulated times comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the current out-of-limit accumulated times and current set value, and determining the maximum current value I of three phases_maxIf the current value is larger than the current out-of-limit accumulated times overrun current set value, starting a current out-of-limit accumulated times timer to time to obtain current out-of-limit accumulated times timing t3, and counting the three-phase maximum current value I_maxAnd the number n is larger than the number of times that the current out-of-limit accumulated number exceeds the set value of the current.

The second current out-of-limit accumulated times comparison circuit is used for three-phase maximum current value I_maxThe number n of times of the current set value exceeding the current out-of-limit accumulated number is compared with the accumulated out-of-limit set value, and if the three-phase maximum current value I is larger than the accumulated out-of-limit accumulated number, the three-phase maximum current value I is detected_maxAnd the number n of times of exceeding the current set value and the current out-of-limit accumulated number is greater than the accumulated out-of-limit number set value of the accumulated time window set value, and the current out-of-limit accumulated number is sent to a current out-of-limit accumulated number and circuit.

The first OR circuit is used for carrying out OR calculation according to the phase current surge criterion signal meeting the light-load operation interval and the overcurrent criterion signal meeting the normal operation interval, if the phase current surge criterion signal meeting the light-load operation interval and the overcurrent criterion signal meeting the normal operation interval are true, the belt conveyor is judged to be in scratch fault, and the first OR circuit sends a fault signal to the switching value output unit 3. The switching value output unit 3 transmits a fault signal to the circuit breaker 8, and the circuit breaker 8 performs a trip operation.

The device can detect the scratch fault of the belt in real time and send out an alarm or automatically trip to prevent the accident from being serious. The belt conveyor has the advantages that investment is not increased, the belt is not damaged, the complexity of operation and maintenance is not increased, the scratch failure rate of the belt conveyor is effectively reduced, the economic benefit of a power plant is improved, and the belt conveyor has high engineering practical value.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims

1. The utility model provides a motor relay protection device for belt feeder fish tail fault protection which characterized in that, includes interchange flow acquisition unit (1), switching value input unit (2), switching value output unit (3), processing unit (4) and current transformer (7), wherein:

the current transformer (7) is used for being installed on a connecting wire between a circuit breaker (8) of the motor (10) and a power bus;

the receiving end of the alternating current quantity acquisition unit (1) is used for being connected with the current transformer (7), and the sending end of the alternating current quantity acquisition unit (1) is connected with the processing unit (4);

the receiving end of the switching value input unit (2) is connected with the circuit breaker (8), and the transmitting end of the switching value input unit (2) is connected with the processing unit (4);

the receiving end of the switching value output unit (3) is connected with the processing unit (4), and the transmitting end of the switching value output unit (3) is connected with the circuit breaker (8).

2. The motor relay protection device for belt conveyor scratch fault protection of claim 1, characterized in that: including voltage transformer (6), voltage transformer (6) set up on the connecting wire between circuit breaker (8) and the power bus, the receiving terminal of interchange volume acquisition unit (1) is used for being connected with voltage transformer (6).

3. The motor relay protection device for belt conveyor scratch fault protection of claim 2, characterized in that: comprises a display communication unit (5), wherein the display communication unit (5) is connected with a processing unit (4).

4. The motor relay protection device for belt conveyor scratch fault protection as claimed in claim 3, wherein: the alarm device comprises an alarm prompting unit (9), wherein the alarm prompting unit (9) is connected with a switching value output unit (3).

5. The motor relay protection device for belt conveyor scratch fault protection of claim 4, characterized in that: the processing unit (4) is a single chip microcomputer.

6. The motor relay protection device for belt conveyor scratch fault protection of claim 4, characterized in that: the processing unit (4) comprises a current extraction module, a first three cycle phase current average amplitude extraction module, a motor running state judgment module, a current sudden increase judgment module, an overcurrent judgment module and a first OR circuit, wherein: the current extraction module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current running state judgment module, the current surge judgment module and the overcurrent judgment module, the current running state judgment module is respectively connected with the previous three cyclic phase current average amplitude extraction modules, the current surge judgment module and the overcurrent judgment module, and the current surge judgment module and the overcurrent judgment module are connected with the first OR circuit.

7. The motor relay protection device for belt conveyor scratch fault protection of claim 6, characterized in that: the current extraction module is used for extracting three-phase current according to the collected current electric quantity; determining to calculate each phase current amplitude I in real time according to the extracted three-phase current_phAnd a three-phase maximum current value I_max；

The motor running state judging module comprises a first closing position judging circuit, a first motor running state comparing circuit, a first motor running state and circuit and a second motor running state and circuit, wherein the first closing position judging circuit is used for judging whether the position of a circuit breaker (8) of the motor (10) is in a closing position or not and sending closing position information of the circuit breaker (8) to the first motor running state and circuit; the first motor running state comparison circuit is used for comparing a three-phase maximum current value I_maxComparing with the light load current high limit value and the light load current low limit value, and if the three-phase maximum current value I_maxWhen the current is between the light-load current high limit value and the light-load current low limit value, outputting a first comparison signal to a first motor running state and circuit; if the three-phase maximum current value I_maxIf the current is larger than the light-load current high limit value, outputting a second comparison signal to a second motor running state and circuit; the first motor running state and circuit obtains a motor light-load running interval signal according to the on-position information and the first comparison signal, and sends the motor light-load running interval signal to the current sudden increase judging module; and the second motor running state and circuit performs AND operation according to the on-position information and the second comparison signal to obtain a signal of the motor in a normal running interval, and sends the signal of the motor in the normal running interval to the overcurrent judging module.

8. The motor relay protection device for belt conveyor scratch fault protection of claim 7, characterized in that: the current surge judging module comprises a starting surge sub-module, a phase current surge value calculating circuit, a first current surge comparing circuit, a first current surge timer, a second current surge comparing circuit, a first timing comparing circuit and a first current surge and circuit;

the starting sudden increase sub-module starts a phase current sudden increase value calculation circuit, a first current sudden increase comparison circuit, a first current sudden increase timer, a second current sudden increase comparison circuit, a first timing comparison circuit and a first current sudden increase and circuit according to the light load operation interval signal sent by the motor operation state judging module;

To memorize the value

Simultaneously starting a first current surge timer for timing to obtain a current surge timing t 1;

Taking the model after the difference to obtain the sudden value of the second phase current;

the second current surge comparison circuit compares the second-phase current surge value with the phase current surge set value, if the second-phase current surge value is greater than the phase current surge set value, a current surge comparison signal is obtained, and the current surge comparison signal is sent to the first current surge and circuit;

the first timing comparison circuit is used for comparing the current surge timing t1 with the phase current surge delay time, and if the current surge timing t1 is greater than the phase current surge delay time, a current surge delay signal is sent to the first current surge and circuit;

the first current surge and circuit is used for carrying out AND operation according to the current surge comparison signal and the current surge delay signal, if the current surge comparison signal and the current surge delay signal are true at the same time, the phase current surge criterion is met, and a phase current surge criterion signal meeting the light-load operation interval is sent to the first OR circuit;

The starting judgment sub-module starts a current continuous out-of-limit judgment sub-module, a current out-of-limit accumulated number out-of-limit judgment sub-module and an over-current judgment or circuit according to a conventional operation interval signal sent by the motor operation state judgment module;

the current continuous overrun comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the current continuously out-of-limit current set value, and if the three-phase maximum current value I_maxIf the current value is larger than the current continuous out-of-limit set value, starting a current continuous out-of-limit timer to time to obtain a current continuous out-of-limit time t 2;

the current duration time overrun comparison circuit is used for comparing a current duration overrun timing t2 with a current duration overrun time set value, if the current duration overrun timing t2 is larger than the current duration overrun time set value, the current duration overrun criterion meeting the overcurrent in a normal operation interval is represented, and a current duration overrun signal of the overcurrent in the normal operation interval is sent to an overcurrent judgment or circuit;

the current out-of-limit accumulated time overrun judging submodule comprises a current out-of-limit accumulated time comparing circuit, a current out-of-limit accumulated time timer, a first current out-of-limit accumulated time comparing circuit, a second current out-of-limit accumulated time comparing circuit and a current out-of-limit accumulated time and circuit;

the current out-of-limit accumulated times comparison circuit is used for comparing the three-phase maximum current value I_maxComparing with the current out-of-limit accumulated times and current set value, and determining the maximum current value I of three phases_maxIf the current value is larger than the current out-of-limit accumulated times and exceeds the current set value, starting a current out-of-limit accumulated times timer to time to obtain current out-of-limit accumulated times timing t3, and counting the three-phase maximum current value I_maxThe number n of times is larger than the number of times that the current out-of-limit accumulated number exceeds the set value of the current;

the first current out-of-limit accumulated time comparison circuit is used for comparing a current out-of-limit accumulated time count t3 with an accumulated time window set value, and if the current out-of-limit accumulated time count t3 is smaller than the accumulated time window set value, sending a current out-of-limit accumulated time count smaller than signal to the current out-of-limit accumulated time and circuit;

the second current out-of-limit accumulated times comparison circuit is used for three-phase maximum current value I_maxThe number n of times of the current set value exceeding the current out-of-limit accumulated number is compared with the accumulated out-of-limit set value, and if the three-phase maximum current value I is larger than the accumulated out-of-limit accumulated number, the three-phase maximum current value I is detected_maxThe number n of times of exceeding the current set value is greater than the cumulative out-of-limit cumulative number of times of exceeding the current set value, and the current out-of-limit cumulative number of times is greater than the cumulative out-of-limit number of times of the cumulative out-of-limit time set value, and a signal is sent to the current out-of-limit cumulative number of times and a circuit;

the current out-of-limit accumulated times and circuit counts and calculates according to the fact that the current out-of-limit accumulated times is smaller than the signal in timing and the current out-of-limit accumulated times is larger than the signal, if the fact that the current out-of-limit accumulated times is smaller than the signal and the current out-of-limit accumulated times is larger than the signal is true at the same time, the current out-of-limit accumulated times out-of-limit criterion which meets the overcurrent in the normal operation interval is represented, and the current out-of-limit accumulated times out-of-limit signal of the overcurrent in the normal operation interval is sent to the overcurrent judgment or circuit;

the overcurrent judging or circuit carries out or calculates according to the overcurrent continuous overrun signal in the normal operation interval and the overcurrent out-of-limit accumulated frequency overrun signal in the normal operation interval, if one of the overcurrent continuous overrun signal in the normal operation interval and the overcurrent out-of-limit accumulated frequency overrun signal in the normal operation interval is true, the overcurrent judging or circuit indicates that the overcurrent judging or circuit in the normal operation interval is met, and the overcurrent judging or circuit sends the overcurrent judging or circuit signal in the normal operation interval to the first or circuit;

the first OR circuit is used for carrying out OR calculation according to the phase current surge criterion signal meeting the light-load operation interval and the overcurrent criterion signal meeting the normal operation interval, if one of the phase current surge criterion signal meeting the normal operation interval and the overcurrent criterion signal meeting the normal operation interval is true, the belt conveyor is judged to be in scratch fault, and the first OR circuit sends a fault signal to the switching value output unit (3); the switching value output unit (3) transmits a fault signal to the circuit breaker (8), and the circuit breaker (8) performs a trip operation.

9. A motor relay protection method for protecting scratch faults of a belt conveyor is characterized by comprising the following steps:

step S1, collecting a three-phase current value and a breaker (8) position when the motor (10) runs; calculating the amplitude I of each phase current in real time_phAnd three-phase maximum current value I_maxWherein, I_phFor the current real-time phase current magnitude, ph A, B, C is the phase difference, I_maxThe maximum value of the three-phase current;

ph A, B, C, T denotes the period;

step S3, passing three-phase maximum current value I_maxAnd position of the circuit breaker (8)Judging whether the motor (10) is in a light-load operation zone or a normal operation zone at present; if the motor (10) is in the light-load operation interval, jumping to the step S4; if the motor (10) is in the normal operation interval, jumping to the step S6;

step S4, real-time judging whether the requirement is satisfied

To memorize the value

And starting a timer to obtain a current surge time t1, wherein I_set3Setting a phase current sudden increase value;

step S5, real-time judging whether the requirement is satisfied

And T1 > T_set1If yes, the phase current sudden increase criterion is met, and the step S8 is skipped, wherein T_set1Delay time is suddenly increased for phase current;

step S6, executing overcurrent criterion in a normal operation interval, including overcurrent continuous overrun criterion in the normal operation interval and overcurrent overrun accumulated times overrun criterion in the normal operation interval;

step S61, determining the overcurrent continuous overrun criterion in the normal operation interval: real-time judgment whether I is satisfied_max＞I_set4And T2 > T_set2(ii) a If yes, the current continuous overrun criterion of overcurrent in the normal operation interval is met, and the step goes to step S7, wherein I_set4For the current continuously exceeding the current set value, T_set2The current duration overrun time setting value is t2, the current duration overrun time is t2 is the initial I_max＞I_set4The timer started after the timer is met;

step S62, the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval is as follows: real-time judgment whether I is satisfied_max＞I_set5，t3＜T_set3And N > N_set(ii) a If yes, meeting the current out-of-limit accumulated times out-of-limit criterion of the overcurrent in the normal operation interval, and jumping to the step S7, wherein I_set5For the current out-of-limit accumulated times exceeding the current set value, T_set3For accumulating the time window set value, N_setSetting value for accumulated out-of-limit times; t3 is I_max＞I_set5A timer started after the first time is met, n is I in t3_max＞I_set5The number of times satisfied; when N > N_setOr T3 > T_set3Then n and t3 are cleared to avoid continuous accumulation;

step S7, overcurrent criterion of normal operation interval: if the current continuous overrun criterion of the overcurrent in the normal operation interval is met or the current overrun accumulated times overrun criterion of the overcurrent in the normal operation interval is met, the overcurrent criterion in the normal operation interval is met, and the step S8 is skipped to;

and step S8, meeting the phase current sudden increase criterion in the light-load operation interval or the overcurrent criterion in the normal operation interval, judging that the belt conveyor is scratched to cause a fault, outputting the fault to the switching value output unit (3), and sending out automatic tripping.

10. The motor relay protection method for belt conveyor scratch fault protection according to claim 9, characterized in that: passing the three-phase maximum current value I in step S3_maxAnd a method for judging the position of the breaker (8) that the motor (10) is in a light-load operation zone or a normal operation zone at present:

if the circuit breaker (8) of the motor (10) is in the closed position and I_set2＞I_max＞I_set1The motor (10) is in a light-load operation region, wherein I_set2For a high limit of light-load current, I_set1A light-load current lower limit value;

if the circuit breaker (8) of the motor (10) is in the closed position and I_max＞I_set2The motor (10) is in a normal operation zone.