CN109417260B

CN109417260B - Electric brush current control system, electric brush current intelligent control system and control method

Info

Publication number: CN109417260B
Application number: CN201680087136.8A
Authority: CN
Inventors: 黄继林; 张树民; 田园
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-07-19
Filing date: 2016-07-19
Publication date: 2020-11-10
Anticipated expiration: 2036-07-19
Also published as: CN109417260A; WO2018014147A1

Abstract

The utility model provides an electric brush current control system, electric brush current intelligence control system and control method, sets up force sensor (3) on the end of carrying of electric brush (1), a controllable power device's active cell (5) with force sensor (3) are connected, through force sensor (3) to electric brush (1) transmission thrust, force sensor (3) rethread controller links to each other with controllable power device, electric brush current loop is connected with shunt (8) or hall current sensor (9) for measure the electric current size that passes through on electric brush (1), shunt (8) or hall current sensor (9) with the controller links to each other. When the power machine is used, when the current on the electric brush (1) measured by the shunt (8) exceeds the upper limit value, the controller sends out an instruction to increase the thrust output by the power motor (4) until the current on the electric brush (1) is lower than the upper limit value; on the contrary, when the current measured by the current divider (8) on the electric brush (1) is smaller than the lower limit value, the controller sends out a command to reduce the thrust output by the force motor (4) until the current on the electric brush (1) is higher than the lower limit value.

Description

Electric brush current control system, electric brush current intelligent control system and control method

Technical Field

The invention relates to a monitoring device and a monitoring method for brush current of a motor in the electromechanical industry, in particular to a monitoring device and a monitoring method for brush current of a large-scale generator slip ring in an electric power system, which have reference significance for monitoring brush current of a small-scale motor.

Background

1. Manual adjustment of brush current: the function of the electric brush is to transmit exciting current, the current is the life of the electric brush, and when the electric brush can not complete the task of normally, reasonably, safely and stably transmitting the current, all indexes of the electric brush have no significance. At present, excitation current of a main generator set in the power industry reaches five thousands to ten thousands of amperes, the number of large electric brushes reaches one or two hundred, the electric brushes are arranged in 4-10 rows (or even more), and when the electric brushes cannot be reasonably distributed, the electric brushes are manually adjusted by operators on duty.

2. Brush current cannot be distributed properly and resulting failures:

excessive brush current:

any article has a problem of use limit, and the articles are difficult to change to a good direction and develop to a malignant direction when reaching and exceeding the limit.

The method comprises the following steps: the normal current carrying range of the graphite electric brush is +/-25% of rated current, and the running time of the graphite electric brush is allowed to be 15 minutes by 1.5 times of the rated current; 2 times rated current allows 60 seconds of running time; the 2.5 times rated current allows a run time of 5 seconds. (the electric brushes applied to most units have the rated current density of 10-12A/cm according to the product of manufacturers₂Short-time allowable current density: 13 to 17A/cm₂The current density exceeds 25A/cm₂When the brush is used, the performances of the brush are deteriorated. )

When the current density is too large, the spark-free operation is difficult, namely, the current density is too large, which is one of the essential factors for generating sparks; the sparks damage the oxide film in the operation of the brush slip ring, and the brush current cannot be reasonably distributed, thereby causing the brush to fail.

The electric brush fault is caused by the fact that the electric brush cannot normally carry current, people can simply understand that the electric brush is damaged and then is replaced, in daily life, the electric brush of household appliances such as an electric drill, a dust collector and the like is damaged, however, the electric brush on a large-scale generator cannot be simply understood, the electric brush fault on the household appliance does not cause serious damage to adjacent equipment, and the electric brush fault on the large-scale generator is usually developed into damage to related and adjacent equipment. It can be seen from a large number of generator brush accident reports that brush failure not only means damage to the brush itself, as well as to compression springs, brush holders, slip rings, but also to upstream and downstream equipment.

The upstream equipment is self-shunt excitation and excitation transformers, so that overcurrent protection action is caused, and interlocking tripping and shutdown accidents of transformers are caused.

Downstream equipment burnout failures such as: burning loss slip ring, insulation cylinder carbonization, burning out of grounding brush, big shaft burning out of pit hole, bush burning, oil system deterioration, etc., and also caused great accidents such as hydrogen explosion, big shaft bending, bearing shaft seat screw vibration breakage, shaft seat displacement, etc.

Brush current goes from being distributed unreasonably to developing a severe accident:

the brush current is excessively high and develops into a current robbing phenomenon, although partial conducting points can be forcibly disconnected in the running process of the slip ring spiral chute, the sliding surface is in a red hot state due to the excessively large brush current, the lubricity and the resistance of an oxidation film are damaged, the whole sliding surface of the brush becomes a good conductor of current, the current cannot be reduced due to the fact that the sliding ring spiral chute runs and disconnects the partial conducting points until a brush braid is burnt off, at the moment, the brush body and the brush holder are high in temperature and become good conductors of current, the current is not always finished after the brush braid is burnt off, the brush holder continues to conduct current, the current can also continue to be increased, and then the brush holder is burnt off. The red heat state of the brush braid, the fused brush holder and the sliding surface is burnt, the oxide film is destroyed, the spark is large, and the ring fire state is formed by the fused mass of the brush holder; the molten material of the brush holder is splashed to the slip ring and the periphery to cause the scraping and crushing action on the brush body, a large amount of red thermoelectric carbon graphite material is ground and dropped, and the slip ring is ignited to enable the slip ring to beThe periphery of the electric brush is in an electric heating, ionization and thermal dissociation state, and the electricity and the fire are formed along with the burning of the electric brush

The discharge, the arc, forms or begins to conduct in the form of an arc (this is the first path of the arc).

The first path of the arc is only one section of the arc and has the closest spatial distance, but the path has rotating and rotating wind, groove wind and vent wind, and the arc cannot be stabilized. The stage is still in the starting stage of burning, the development time of the stage is long (more than 10 minutes) from the accident notification, and in the stage, what type of rotor grounding protection can not be reflected because the rotor is not grounded; the excitation output voltage recorded by the fault recorder fluctuates repeatedly and increases, but the amplitude is not too large.

And (3) an arc discharge development stage: the electric arc develops to the fan and the outer shell cover under the action of rotating wind and the air draft of the fan; after that, the periphery of the slip ring and the periphery of the fan are exposed to electric fire and electric arc, and the electric dissociation and the thermal dissociation make the slip ring, the large shaft near the slip ring, the fan, the housing cover and the periphery thereof in an ion conducting state, thereby providing favorable conditions for opening an arc discharge path.

An arc second path:

burning out fans, large shafts, slip rings, insulation barrels, etc.

Arc third path:

the large shaft is dangerous to discharge the conductive screw and the rotor lead wire, so that the long lead wire of the rotor, the conductive screw, the pressing cap of the conductive screw and the sealing ring are burnt and broken; the hollow hydrogen of the rotor can cause 'hydrogen explosion', the other end of the long lead of the rotor is also sealed, so that the accident of the serious hydrogen explosion is not caused, but the accident of the hydrogen explosion caused by the fire of the electric brush is once occurred in China.

The large shaft discharges electricity to the conductive screw and the long lead wire of the rotor, and the long lead wire is burnt out to perform 'magnetic loss protection action' to jump the machine.

Arc fourth path:

or a conductive screw. The grounding brushes are easily blown.

The arc second, third and fourth paths typically have two arcs.

Arc fifth path:

or a conductive screw.

From the notification of the brush burning accident, the electric arc is not developed into the whole process of five paths every time the brush burning accident happens, and the electric arc cannot be developed again when the machine is stopped or jumped in a certain process.

The fifth path of the electric arc has three sections of electric arc discharge, wherein one section is that the bearing bush discharges to the large shaft. The electric arc reaches grounding bodies such as a shell cover, and after the grounding electric brush is burnt, the electric arc seeks a discharge path (except for a bearing seat with an insulating interlayer) among all the bearing bushes; after such a faulty unit has occurred, it is often found that more than one bearing shell is burned by the arc and the turbine oil is also degraded, when the bearing blocks are opened and the bearing shells are inspected.

When the second path of the electric arc is started, the large shaft participates in the electric arc discharge, and the depth of the large shaft is 8mm of a pot hole when the large shaft is burnt by the electric arc; in addition, the fan is burnt by electric arcs, so that the vibration of a set shafting is large, and the 'vibration protection action' jumps; the serious damage accidents include vibration damage, burning of the bearing bush, breakage of the bearing block bolt and displacement of the shaft seat.

Why does the arc take the closest path erratically, but rather leaves the other path far around the coil? The analytic conclusion of academic experts and motor plant experts after the accident is seen as follows: other paths may cause the discharge site to be relatively stationary and maintain a stable arc. In the event of an accident, the large shaft is burned by electric arc, namely, a deep hole or a plurality of holes are burned in one or a plurality of fixed parts of the large shaft instead of burning along the circumference of the large shaft.

The arc discharge is arbitrary and inexorable, no matter metal conductors, insulating materials, cement, ceramics, glass, resin and the like, in the presence of high-energy arcs, the arcs are burnt, smelted and even gasified, the related equipment at the primary level and the subordinate level are destroyed together, and if the equipment is not stopped by the equipment at the primary level in time, the equipment at the primary level and the subordinate level are destroyed together with the equipment at the secondary level and even the equipment at the subordinate level. If the brush accident causes excitation change to cause overcurrent protection action, the machine jumps.

Then do the arc discharge energy account for the energy supplied by the excitation power supply? According to a research article published by a provincial electric academy in 2007, in the case of a 100MW unit accident, the calculated arc energy accounts for about 60%, and the arc power exceeds 180KW according to the data of a fault recorder. Therefore, it is also possible to estimate the arc discharge power of the electric brush of the giant unit to reach 800KW, the slip ring, the fan, the large shaft and the like are burnt by the huge arc energy, and the large shaft is mostly returned to a motor factory for repair due to the accidents in recent years.

The conditions of the protection action and the trip of the brush burning accident are as follows: the 'unit vibration protection action' tripping, the excitation change 'overcurrent protection action' tripping, and the 'loss of excitation protection action' tripping caused by burning out the excitation current loop (such as 'long rotor lead' being blown); the main protection, namely the ground protection, often fails to operate correctly, and the consequences caused by the condition of the override actions of the main protection are serious. The practical application of each type of rotor ground protection is not less than five types, but each type of rotor ground protection has unsatisfactory aspects, even has misjudgment and dead zones, and moreover, the rotor ground protection is required to be provided with time limit protection, arc discharge is unstable, and wave recorder data in a fault example also explains the time interruption of grounding signals, which become factors influencing the accurate action of the ground protection.

Brush current is too small:

the generator graphite brush is matched with the steel slip ring for use, and the stable current density is 6-8A/cm during design₂And sufficient margin is less than 3-5A/cm₂It is difficult to form an oxide film and even cause dry friction.

Articles used in life are generally understood to be smaller and safer under the rated value, for example, an automobile carrying 10 tons only carries 1 ton, and is safe; however, the brush cannot be understood in this way, for example, the brush with rated current of 100A, the operation below 10A is not the safest and stable, but is disadvantageous to the safety and stability of the brush; both basic theory and operating experience show that: the brush can not form good oxide film even destroy the oxide film under light load. In order to prevent the fault caused by the over-small current of the electric brush, some unit requirements exist, and when the generator runs under light load, part of the electric brush is withdrawn from running. Survey statistics have been introduced abroad many years ago, and some faults of the electric brush, more than 85 percent of which are caused by light load of the electric brush, are caused. In the last 70 th century and before, theoretical knowledge and research on electric brushes are not mature, the more electric brushes are installed, the better the unit unipolar of 100 MW-160 MW reaches 40-60 electric brushes, at that time, even if half of the electric brushes are abnormal, the other half of the electric brushes can meet the unit operation requirements, the conclusion is drawn along with deep theoretical knowledge on the electric brushes and electric brush fault conditions in actual operation, the more electric brushes are better, the capacity of the unit in a new period is increased greatly, but the quantity of the electric brushes is not increased, for example, the capacity of the giant unit with the power of 700MW is increased by several times, only 36 electric brushes are used for design (the current-carrying ratio area is about equal to the past 50, the quantity of the electric brushes is not increased, and the burning accidents of the severe electric brushes are reduced; the same conclusions are drawn from theory and practice to prove that: the brush current is larger than 50% of rated current to operate safely, stably and reliably, and the current is harmful when being too small.

The influence of undersize current is seen by taking the temperature which is easier to understand in the running process of the electric brush as an example, the sliding running of the electric brush at the temperature of 60-120 ℃ is safe and stable, the temperature is too high and too low and is unfavorable for the running of the electric brush, attention needs to be paid to the fact that the temperature is the temperature of the sliding working surface of the electric brush, the temperature cannot be measured in the running of the electric brush and the sliding ring, the surface temperature of the sliding ring and the temperature of an electric brush body and a brush holder which can be measured daily are much lower than the numerical value, the current of the electric brush is small and cannot reach the temperature above 60 ℃, and the safe and stable.

3. No protection and no control are performed during the operation of the electric brush:

the electric equipment which is contacted and known by people has even more than one set of protection, no protected electric equipment and elements are arranged or not arranged, the operation is forbidden, the daily used household appliances and the contacted industrial electric equipment are provided with or have multi-stage protection such as main protection, backup protection and the like, and when the equipment and the elements have faults anywhere, the protection action withdraws the electric loop or cuts off the power supply, so that the equipment is protected and is prevented from being damaged more seriously. Some important devices such as generators and transformers are protected by dozens of types, even if one main protection needs to quit operation due to reasons, the main protection reports a main manager or a dispatch of a central office and related superior technologies, the time for the main protection to quit operation is strictly controlled, and the main protection quit operation needs to carry out system stable accounting and make preventive measures and accident plans.

The brushes, the core component that directly serves the generator "heart", are not only unprotected, but also have no control means.

If the electric equipment, the element and the component have low value, if the fault damage does not cause bad influence, the upper and lower levels and adjacent equipment are not involved, and no protection is realized; once the brushes do not operate properly, the resulting failure results will involve the upper and lower stage devices.

It can be seen from the brush accident report that the initial stage of the fault is developed for a long time, and in some accident reports, the stage is described as "slow", and although the stage is developed for a long time, the arc is formed and discharged, and the energy of the arc is increased, and at this time, the arc discharge with energy is artificially processed, so that a great risk is created for personal safety.

4. Brush holder shunting phenomenon:

when the electric brush runs, the brush holder is mostly a good electric conductor, a person on duty measures the electric brush current, namely, the current is measured by a card meter to measure an electric brush braid, the current is measured from the electric brush braid by the conventional automatic current monitoring device, the sum of the electric brush current and the total excitation current have certain deviation no matter the electric brush current is measured manually or automatically, the serious time difference is even more than 40%, the phenomenon of brush holder shunt current exists, when the electric brush is adhered to the brush holder, particularly when the electric brush braid riveting part has large resistance, the shunt current of the brush holder is very large, even the electric brush burnout accident is directly caused, and the problem of shunt current of the brush holder in the running of the electric brush is always a dead zone which cannot be monitored. The brush holder shunts and even leads to the rapid collapse of the safe operation of the brush, and no sign is given in advance: the pressure and the current are normal, but the accident happens firstly, the evidence is destroyed, so that the analysis is not successful, and people can only consider the problem of the electric brush.

In the past, brush failure analysis reports were: the brush is ignited, the actually measured sparking brush current is very small or even zero, and the conclusion is that the brush sparking is independent of the current, namely the conclusion is wrong, the brush no-current is sliding mechanical friction, the brush sparking cannot be continuously and seriously ignited, and the brush sparking is actually caused by brush holder shunt.

Disclosure of Invention

The invention aims to provide an electric brush current control system, an electric brush current intelligent control system and a control method, so as to realize intelligent monitoring, regulation, control and protection of electric brush current.

In order to achieve the purpose, the invention adopts the technical scheme that:

the utility model provides a brush current intelligence control system which characterized in that: set up force transducer on the end of drawing at every brush, controllable power device is connected to every force transducer, controllable power device passes through force transducer to brush transmission thrust, force transducer links to each other with controllable power device through the controller again, brush current loop is connected with shunt or hall current sensor for measure the electric current size that passes through on the brush, shunt or hall current sensor with the controller links to each other, and brush current's size mainly is through brush pressure control and control.

The brush current intelligence control system, wherein: and when the vibration sensor measures that the amplitude and/or the frequency of the electric brush exceeds a preset value, the controller retracts the mover (the quantity of retracted electric brushes needs to be controlled) through the controllable power device.

In order to achieve the above object, the present invention further provides a brush current control system, characterized in that: the rotor of one power device transmits fixed thrust to the electric brush, the electric brush current loop is connected with a current divider or a Hall current sensor and used for measuring the size of current passing through the electric brush, the current divider or the Hall current sensor is connected with a controller, and the controller is connected with the power device.

In order to achieve the above object, the present invention further provides an intelligent control method for brush current, each brush of the generator is connected with the intelligent control system for brush current, and the intelligent control method is characterized in that:

if the current of a certain brush is overlarge, namely the current value is more than or equal to 2 times of the rated current of the brush: the electric brush is directly withdrawn;

if the current of a certain brush is too large, namely the current value is more than or equal to 1.5 times and less than 2 times of the rated current of the brush: gradually reducing the pressure of the electric brush until the pressure lower limit set value is reached, and lifting the electric brush to a state to be judged, wherein the current still cannot recover the normal range after three times of lifting and operation;

if the current of a certain brush is larger, namely the current value is more than or equal to 1.15 times and less than 1.5 times of the rated current of the brush: gradually reducing the pressure of the electric brush until the pressure lower limit set value is reached, and restoring the electric brush current to the normal range through pressure regulation;

if the current of a certain brush is small, namely the current value is less than or equal to 0.5 times and more than 0.25 times of the rated current of the brush: gradually increasing the pressure of the electric brush until the pressure reaches a set value of a high limit, and restoring the current of the electric brush to a normal range through pressure regulation;

if the current of a certain brush is too small, namely the current value is less than or equal to 0.25 times of the rated current of the brush: gradually increasing the pressure of the electric brush until the pressure reaches a set value of a high limit, and lifting the electric brush for three times and putting into operation until the current still can not be recovered to a normal range, and lifting the electric brush to a state to be judged.

In order to achieve the purpose, the invention also provides an intelligent control method of the brush current, each brush of the generator is connected with the intelligent control system of the brush current, and a polishing brush and an arc extinction brush are additionally arranged on the running track of the brush; the method is characterized in that:

if the average current of a certain whole row of electric brushes is larger than the average current of other rows of electric brushes, polishing the brushes and arc suppression brushes to process the oxide film, and then gradually processing the electric brushes with larger current in the row of electric brushes respectively, namely reducing the pressure of the electric brushes to a low limit value until the average current of the row of electric brushes is within a specified range relative to the average current of other rows of electric brushes;

if the average current of a certain row of brushes is smaller than that of other rows of brushes, the brushes are polished and arc-extinguishing brushes are operated to process the oxide film, and then the brushes with smaller current in the rows of brushes are processed step by step, namely the brush pressure is increased to a high limit value until the deviation of the average current of the rows of brushes relative to that of other rows of brushes is within a specified range.

a temperature sensor is arranged at the position, close to the slip ring, of the brush holder of each electric brush, and the temperature sensor transmits a temperature signal to the controller;

if the temperature measured by the temperature sensor reaches 135-140 ℃ or even higher, the corresponding electric brush is withdrawn, and an informing signal is sent out;

and if the temperature measured by the temperature sensor reaches 115-135 ℃, reducing the pressure of the corresponding electric brush and sending a high temperature signal of the electric brush.

comparing the sum of the currents of all the electric brushes with the total exciting current, if the deviation exceeds the set allowable range, starting a brush lifting procedure, namely lifting the brushes one by one, and when one electric brush is lifted, calculating the comparison difference value between the sum of the currents of all the electric brushes and the total exciting current, and when the difference value is obviously reduced when a certain electric brush is lifted, informing a person on duty to handle or withdraw the electric brush by a computer.

a vibration sensor is arranged on the extending end of the rotor to measure the vibration of the electric brush;

if the vibration of a certain row of electric brushes reaches a set value through measurement, the polishing brushes and the arc extinguishing brushes of the row act to process the oxide film;

if a single brush in a row vibrates, and the other brushes in the row do not vibrate, the single brush is retreated and a notification signal is sent, and a person on duty checks the process.

when the exciting current of the generator is 60% or less of the rated current, the brushes 1/5-1/3 are sequentially reduced to operate, and the number of the brushes in operation is positively correlated with the magnitude of the exciting current.

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

1. the protection, control and regulation of the generator brush are realized:

the electric brushes, which are important components of the generator excitation system, are in an unprotected, uncontrolled and even unmonitored state under most conditions, namely the magnitude of the current carried by each electric brush is in a free working state of an unlimited measure; although modern large units use up to one or two hundred brushes, failure of one of them can result.

And (4) protective measures: when the current of the electric brush reaches the setting value of the protection action, the electric brush is immediately (without time limit protection measures) quit to operate and sends out signals, thereby cutting off an accident chain and eliminating accident hidden dangers.

And (3) adjusting measures: the current of the electric brush deviates from the set normal running current value, and the automatic control takes the adjusting measure.

And (3) control measures: the current of the electric brush deviates from the set normal running current value, the range is too large, measures (such as pressure regulation) are automatically controlled to reach the set limit, and the electric brush is lifted to be judged (to be further judged) through a preliminary inspection process (such as three times of lifting and putting into operation), so that the trend that the electric brush develops towards an abnormal direction is controlled, the seedling of the electric brush fault is eliminated, and the electric brush accident is eliminated in a sprouting state.

Electric brush crisis protection: when the electric brush with overlarge current is withdrawn, the emergency standby electric brush is put into operation continuously, and the electric brush with overlarge current needs to be withdrawn, an electric brush unsafe alarm signal is sent out, and a signal for reducing the excitation current of the generator is sent out; if a limit number of brushes which can be retreated is set (for example, one-thirtieth to one-tenth of the number of the running brushes), then no retreating occurs no matter what the condition happens, if the brushes with overlarge current need to be retreated, the safe running of the brushes is shown to be in a dangerous 'after-the-front' deterioration development state, at the moment, a 'generator load reduction' instruction is sent out, and the generator exciting current is greatly reduced by reducing the generator load so as to achieve the purpose of protecting the main equipment. Therefore, the protection of the single electric brush realizes the function of protecting the main equipment, and becomes a component of the protection of the generator, namely, a set of protection device is added for the safe operation of the generator, and for the protection of the generator, the set of protection can be called as 'electric brush crisis protection'. Before the protection action, the method also has predictability, namely, each brush has overlarge current and the brush retreats, a notification signal is sent, the brush retreating quantity and the time interval are known in advance, and a warning signal for reducing the excitation current of the generator is sent, so that the safety of the brush is in an extremely dangerous development state, and a person on duty should take a targeted measure to work before the protection action, so that the abnormal running of the brush is eliminated at the initial stage of dangerous development.

The tension and psychological pressure of the person on duty are eliminated:

the prior art mainly depends on regular inspection and judgment of an operator on duty, even if a current and other parameter monitoring device exists and the operator on duty is informed of processing by an alarm signal when the current and other parameter monitoring devices exceed a set range, but the processing measures are different from the technical level due to human feeling judgment, an effective programmed processing scheme does not exist, and the alarm reminding actually causes the psychological states of 'tension', 'difficulty' and 'embarrassment' of the operator on duty.

When the automatic regulation control measure is not available, the manual regulation of the operation parameters of the electric brush becomes a component of the safe operation of the electric brush. When an abnormal condition of the electric brush occurs, the 'danger moment rushes ahead' becomes an occupational technology sensitivity idea of electric brush workers, which is an old and unscientific safety idea advocated by almost all industries in the prior art, and countless disastrous results are taught: the dangerous moment rushes ahead often causes bigger danger and even disasters, the primary disaster is not properly treated, and the induced secondary disaster may cause more dangerous consequences than the primary disaster, resulting in a series of disaster chains. Chain lock reaction, vicious circle and domino are used in a large number of brush accident analysis reports, so that the development rate, the simultaneity, the timeliness and the sequentiality of manual treatment are difficult to guarantee, and once the manual treatment is not ideal and deteriorates, the loss is very disastrous and even causes personal danger.

The invention realizes the automatic regulation, control and protection of the processes of over-small current to over-large current of the electric brush.

2. The brush is good to use, durable judgement, practices thrift the brush, scientific management:

judging the good use and durability of the electric brush:

the brush is easy to use and durable, and the user can not speak the data.

The electric brushes are automatically controlled by indexes such as pressure, current, temperature, vibration and the like in the running process, the computer records the service time (time and length relation curve) of each electric brush and the index curves and the adjustment control times, and the service time is checked, compared and sequenced with the requirements of good use performance of the electric brushes so as to judge that the electric brushes are good in use and durable, the good use is to meet the requirements of good parameters of the use performance of the electric brushes, and the durability is to ensure that the electric brushes are stable in use and long in service life.

The electric brush is manufactured only by manufacturing static parameters instead of specific applicable products, the electric brushes used on the existing generators are all universal products, and the electric brushes can be applied only by personalized customization of products, so that the electric brushes are applicable to the products. An important direction of the product manufacturing and developing concept is to simplify the use questions to the greatest extent, and the dynamic parameters of the electric brush in use are not famous and are not known by experts, are controlled, recorded and counted by a computer, and are simple to use and popular.

Saving electric brushes: at present, a generator set runs on a slip ring all the time no matter how many brushes are installed, and all brushes run under any condition from starting, light load, full load to forced excitation action. Especially, the current density of the electric brush is too small when the electric brush is in a low valley and under light load at night, which is unfavorable for a plurality of indexes of the electric brush operation, and simultaneously wastes the electric brush and abrades the slip ring. The generator runs under light load and reduces the abrasion of the slip ring, the electric brush is saved, and the current density of the electric brush is not too small so as to be beneficial to forming a good oxidation film. The energy consumption of ventilation can be reduced by reducing the friction heat during the brush operation.

Scientific management: the computer automatically prints out a work ticket and an operation ticket for replacing the electric brush: the machine set increases the total quantity of the installed electric brushes, realizes that part of the electric brushes are on standby, when the electric brushes quit operation, the standby electric brushes are put into operation automatically, when a small quantity of the electric brushes reach the service life or can not operate normally and quit operation, the computer records and can check in real time, when most of the standby electric brushes are put into operation or quit operation, the computer automatically prints out and replaces electric brush work tickets and operation tickets and informs operators on duty, the names, positions and numbers of the electric brushes work correspond, the operators realize three checks, even the types of the electric brushes, the specific numbers of each electric brush of the unit, and the reasons for replacing each electric brush, such as super-high current, super-high temperature, over-high current and the like, are also included in the operation tickets, and the electric brushes which can not be replaced and can not be replaced by more or less replaced along with different personal judgment recognitions; the computer automatically generates a working ticket for maintaining and replacing the electric brush of one machine, thereby avoiding the problem of work quality reduction due to large workload and the hidden danger of serious consequences caused by personnel fatigue. Meanwhile, random emotional factors of manual assignment work are avoided, and factors of withering and tearing work of operators on duty are avoided. The realization technology makes a contribution to scientific management.

3. Reducing the grinding slip ring:

(1) "brush sliding friction self-vibration":

at present, the number of large electric brushes used by a main generator set in the power generation industry is one to two hundred, the single poles are installed according to 4-10 rows (even more), the electric brushes operate stably at first, and in the operation process, a small number of the electric brushes, one row or a plurality of rows gradually develop large vibration, and the rest rows operate normally; this is a typical manifestation of brush sliding friction self-oscillation.

The brush has free movement clearance in the brush holder, the sliding operation of the brush actually comprises processes of pause, acceleration, intermittence, deceleration and the like, and the process itself comprises instability of the sliding operation; instability and nonuniformity of sliding, and a sliding friction coefficient are also fluctuant, the fluctuation of the sliding friction exists at any time, but the brush is not vibrated at any time, and when the fluctuation value is small (such as delta mu/mu is approximately equal to or less than 5 percent), no vibration is shown to the outside; when the fluctuation value is large (such as delta mu/mu is approximately equal to 10-15%), vibration begins to be expressed outwards; in this case, the vibration may progress toward deterioration without interfering with the sliding friction coefficient. The oxide film is damaged and bad, the friction coefficient mu is increased, if the friction coefficient mu is small, the friction fluctuation delta mu/mu is not large, and the brush sliding friction self-vibration is not deteriorated and developed. The friction fluctuation is large, and when the friction fluctuation is expressed towards the vibration development, the oxide film is further destroyed firstly, so that a series of adverse effects are caused: current increases, temperature increases, vibration increases. This is that we actually measure that there is current when the brush vibrates, and the current tends to increase.

The sliding matching surface of the electric brush slip ring has adhesion and sealing factors; the parameters (friction force, friction coefficient and speed) of the electric brush have step expression; the sliding and conductive micro-pulse is provided; this is a factor causing the sliding friction of the brush to vibrate itself.

With the continuous increase of the vibration of the electric brush, the phenomenon of electric brush jumping is developed, and an electric brush hammering phenomenon is developed, (the electric brush, a brush braid, a brush holder, a pressure spring and other accessories are damaged), so that the damage to the slip ring is caused, and the slip ring is forced to be subjected to the grinding.

(2) The difficulty of studying the vibration and hammering of the electric brush is recognized:

the electric brush vibration fault, electric brush manufacturer and electric brush research unit, i.e. scholarly expert, can not be simulated in the laboratory, the electric generator usually does not attract the attention of operators on duty when the electric brush vibration fault occurs at the beginning, and the electric brush vibration fault is difficult to process and recover when the electric brush vibration fault occurs. The field personnel knows the vibration and hammering phenomenon, experience and experience are needed to obtain higher-level cognition, even though the vibration and hammering phenomenon is subjected to multiple times of vibration, the law is difficult to be summarized from field research, the vibration and hammering phenomenon is increased to the theoretical height, the vibration and hammering phenomenon on the field often has the specific limitation, namely the vibration and hammering phenomenon is different from the specific environment where the generator is located, the interference is different, and the field personnel on duty can experience and relate to the generators of different types and relate to the brush vibration faults for the multiple times.

(3) Wear and damage of brush slip rings: slip ring wear is mechanical wear + galvanic wear + spark damage.

Mechanical abrasion: mechanical abrasion during normal operation; secondly, after the spark damages the oxide film, the sliding lubricating film is uneven or the mechanical abrasion is caused when no film exists; and mechanical abrasion after the spark product participates.

Current abrasion: when the electric brush slip ring normally operates, the conductive points are uniformly dispersed, the energy of the conductive points is very small, and the pulverization and evaporation effects are also very small.

Spark damage: after the spark is generated to destroy the oxide film, the energy of partial conducting points is gathered, and the pulverization and evaporation actions are greatly increased to cause spark damage.

(4) "brush hammering phenomenon":

if the vibration of the electric brush cannot be timely and correctly intervened and inhibited, the phenomenon of electric brush jumping is shown along with the continuous increase of the vibration of the electric brush, and an 'electric brush hammering phenomenon' is developed to cause damage to the slip ring and force the slip ring to be subjected to the running abrasion.

In recent years, fault analysis introduces that a new unit has to be stopped to grind the slip ring after running for about two months, and articles also introduce that one unit is ground for more than seven times a year.

How do brush vibration, channeling, and hammering damage the slip ring?

Brush vibration, jumping, hammering, people first think that the brush collides with the slip ring, [ for easy understanding, we see the story of the drippage stone, and the scientific understanding has two aspects: firstly, water drops collide with stones, and the destructive effect of the collision is very small; secondly, the composition of the stone contains CaCO₃Air contains CO₂They react chemically: CaCO₃+CO₂+H₂O＝Ca(HCO₃)₂I.e. to generate Ca (HCO) dissolved in water₃)₂(ii) a There is thus a statement of aquaria. Because the brush and the slip ring have large differences in hardness, toughness and momentum, the impact of the brush on the slip ring is not a main factor causing damage to the slip ring. When the phenomena of vibration, jumping and hammering of the electric brush occur, the electric brush impacts firstly and quickly destroy an oxide film layer on a sliding surface, lubricating components beneficial to sliding operation of the electric brush are destroyed, a sliding friction coefficient is increased, then the sliding operation of the electric brush is more unstable, the vibration is further increased, and the self-recovery cannot be realized; furthermore, the oxidation film is damaged, the properties of conduction, breakdown, discharge and the like in the brush conduction theory are also changed, meanwhile, the oxidation film has the property of resistance, the original normal brush conduction needs to pass through the resistive oxidation film and then reach the slip ring, after the oxidation film is damaged, the brush and the slip ring are directly conducted without an intermediate resistance link, so that when the brush vibration phenomenon occurs, the current of the vibrating brush is measured, the current is not only present, but also is increased compared with the brush current when the brush does not vibrate in most cases, namely the brush conduction current of the resistance component of the vibration damage oxidation film is easier.

Spread and damage:

carrying out sweep: only a small amount of or a row of electric brushes vibrate to destroy an oxide film, so that the friction coefficient mu is increased, the friction fluctuation is increased, the electric brushes which do not vibrate originally are gradually affected to start to vibrate, for example, adjacent waves, namely vibration of one or a certain row of electric brushes vibrate to break the electric brushes, brush braids, compression springs and other accessories, and the broken objects damage the adjacent electric brushes and induce vibration to cause the electric brushes to fail.

And (3) injury: the electric brush jumps, the current is very large when contacting the slip ring, the current is zero when jumping, the current is switched on and off to directly cause electric brush sparks, the current is very large and generate sparks, namely under the action of energetic sparks, the electric brush sparks are accompanied with various damages to the slip ring caused by currents such as spark discharge, burning, gasification, evaporation, pulverization and the like, the damages are totally classified into electric burning and electric erosion, namely the electric brush vibrates, and the slip ring appears to have no brightness (smoothness), and the surface of the sliding ring has the consequences of pockmarks, micro pits, pits and depressions, which are obviously not caused by electric brush collision factors, and the 'streak' and 'gradient' on the slip ring are not caused by electric brush collision factors; therefore, the main factor of damage to the slip ring is not impact, but electric current damages the slip ring through electric ignition and electric corrosion. It follows that: brush vibration cannot be simply regarded as a problem of mechanical vibration, but is mainly a problem of damage caused by electric current.

If technical measures are not taken from the effective control of current, the operation is only busy with the appearance of brush vibration, and some units are only informed to the steam turbine profession to measure the vibration of the unit system as long as the brush vibrates, and the fault of brush vibration is torn and withered with the steam turbine profession, which is the prejudice of inequality and understanding of the profession and can not catch the root cause of contradiction and is idle.

In the past, even if a smaller unit is used, a larger-size slip ring (the diameter of the slip ring of the high-speed unit is more than 450 mm) is used, along with scientific and deep knowledge, the size of the slip ring is smaller (the diameter is less than 400 mm) in the existing large-sized unit (600MW and more), the room for the slip ring to be ground is smaller, and the slip ring can be replaced after being ground for a plurality of times. The existing power generation units do not have or do not have technologies and equipment for turning and grinding the slip rings, turning and replacing the slip rings are a great project, if the turning and grinding of the slip rings can bring safe operation for a long period, the turning and grinding of the slip rings are certainly possible, but the fact is not so, and the turning and grinding of the slip rings are forced and are inevitable post-remedial measures.

(5) Our idea and treatment:

the object is to grind: the slip ring is damaged by vibration and hammering of an electric brush and sparks, and scratches, grooves, gradients, steps, out-of-round and the like are forced to perform grinding on the slip ring, some grinding methods are more than 15mm, the slip ring has to be replaced, and particularly, the slip ring of a large-scale unit in the power industry is designed to be a wear-resistant steel ring, and the design concept is to achieve the purpose of long-term safe operation. We advocate that through the continuous scientific maintenance of the brush slip ring, namely through controlling the brush current and the oxide film in operation, the brush slip ring fault is eliminated at the beginning of germination and the condition generated by the fault is eliminated, so that the brush slip ring is kept in a good and stable operation state for a long time, and the slip ring is not damaged so as to achieve the purpose of long-term non-grinding.

The turning and grinding is not necessarily safe and is a necessary way, the turning and grinding is a passive and forced remedial measure rather than an active and active preventive measure, in other words, most units do not have the turning and grinding technology and equipment, even if the turning and grinding is a unit technical strength item, the smoothness of a slip ring after the turning and grinding is about 6 grades generally, and the thickness of about ten thousand layers of electrical carbon graphite; the thickness of about 600 layers of electrical carbon graphite even reaching the maximum grade 10 required by the smoothness of the slip ring; the unevenness thereof also far exceeds the thickness of the normal oxide film. The grinding is a technical means of remedy and recovery, the value of the grinding is discounted, even the value is negative, the grinding is forced to replace a slip ring too much, the grinding is not work which can be completed by a general unit, and most units have to resort to manufacturers.

In a laboratory, the problem of abrasion of the brush slip ring is studied at home and abroad under the condition of electrification, the slip ring is simply calculated according to relevant experimental data under the condition of no obvious damage, the slip ring is abraded for 1mm under an ideal condition and needs to continuously operate for 10-30 years, and the slip ring can be operated safely for a long period by a scientific maintenance and effective control means of the slip ring.

The concept of not grinding is not the same no matter how round the grinding is. In the experience of operating a brush slip ring of a large generator for decades, the slip ring damage problem is avoided by the concept of controlling the current of the brush and the sliding friction coefficient (oxide film) of the brush, the slip ring is not claimed to be turned and ground, but turning and grinding are prevented, and in a unit which is prevented from being turned and ground, the unit is not turned and ground until the service life is over.

4. Network:

the real-time information of the operation of the electric brush slip ring enters a regional network, an industrial network and the Internet, the self-information and the associated information of the relevant parameters of the electric brush slip ring coordinate the action, store and record data, exchange and study, facilitate the operation analysis, realize the integration of computerization, networking, intellectualization, protection, control, measurement and data communication, and advance from manual control to intelligent automatic control.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of an intelligent brush current control system provided by the present invention;

fig. 2 is a schematic structural diagram of another embodiment of the intelligent brush current control system provided by the invention.

Description of reference numerals: an electric brush 1; a brush lifting mechanism 11; a brush holder 21; a temperature sensor 22; a slip ring 2; a force sensor 3; a force motor 4; a mover 5; a positioning recess 51; a spring pin 52; a vibration sensor 55; a linear position sensor 6; a push-pull electromagnet 7; a spring 71; a flow divider 8; a hall current sensor 9.

Detailed Description

To facilitate an understanding of the present invention, some technical terms in the art are explained herein.

The noun: the method comprises the following steps of brush reduction, brush lifting, brush withdrawing, standby electric brushes, electric brushes which are about to reach the set service life, electric brushes to be judged and emergency standby electric brushes.

(1) Reducing brushing: reducing the number of brushes in operation is to lift a portion of the brushes in operation.

(2) Carrying and brushing: the running brush is lifted up to be temporarily withdrawn from running.

(3) Removing the brush: the brush is directly taken out of operation and is no longer put into operation in any case (for example, brushes with excessive current and excessive temperature).

(4) Standby electric brush: based on the number of the primary brushes, a part of brushes are installed as spare brushes.

(5) Brush to set life: the electric brush quits from running before the service life is ended, and 1-3 mm of the electric brush is reserved for emergency.

(6) The electric brush to be judged: for example, the current is too large and too small, the pressure regulation gradually reaches the set limit of the adjustable pressure, the current still can not recover the set range, the brush is lifted, the current is in a state to be judged at the moment, because the current of the brush is not only related to the pressure but also related to the oxide film, even related to the working condition of other brushes, a new oxide film is in a stable state after the oxide film is treated for a while, or the running condition of the brush is judged through manual inspection, and the intelligent analysis control system further judges the brush of which the lifted brush is in the state to be judged.

Judge the brush that the electric current undersize was mentioned earlier one by one, judge the brush that the electric current is too big was carried the brush one by one afterwards, the judgement process: when the single operation and pressure regulation are carried out, if the brush current can be in a set range, the brush current is maintained in the operation state for continuous use (the original backup brush which is automatically thrown by the lifted brush is withdrawn from the operation and returns to the standby state), and the problem that the first lifting is not or not the brush is not the self problem is explained. If the current of the electric brush can not be in the set range after the operation, the problem of the electric brush is shown, and the electric brush is retreated for replacement (manual detection).

(7) Emergency backup brush: when the electric brush runs and emergency or emergency needs occur, the electric brush which can be put into operation is put into operation according to the setting; the emergency backup brush includes: the electric brush is used for judging whether the current of the electric brush is still too small or not.

As shown in fig. 1, which is a schematic structural diagram of an embodiment of an intelligent brush current control system provided by the present invention, one end of a brush 1 contacting a slip ring 2 is referred to as a contact end, the other end of the brush 1 is provided with a brush lifting mechanism 11 and referred to as a pull end, a force sensor 3 is disposed on the pull end, a mover 5 of a force motor 4 (a linear motor taking output thrust as a target task) is connected to the force sensor 3, the force sensor 3 transmits thrust to the brush 1, and the force sensor 3 is connected to the force motor 4 through a controller (not shown); the current loop of the electric brush 1 is connected with a shunt 8 and used for measuring the current passing through the electric brush 1, and the shunt 8 is connected with the controller.

When the current on the electric brush 1 measured by the current divider 8 exceeds the upper limit value, the controller sends out an instruction to reduce the thrust output by the force motor 4 until the current on the electric brush 1 is lower than the upper limit value; conversely, when the current measured by the shunt 8 on the electric brush 1 is smaller than the lower limit value, the controller sends out a command to increase the thrust output by the force motor 4 until the current on the electric brush 1 is higher than the lower limit value.

A linear position sensor 6 is further connected to the mover 5 for recording the extension distance of the mover 5, thereby calculating the remaining length of the brush 1, and the linear position sensor 6 is connected to the controller. If the force motor 4 itself has a sensor element that can perform the function of a position sensor, the force motor 4 forms the linear position sensor 6. If the force motor 4 does not have a position sensor function, a linear position sensor 6 can be provided separately, as shown in fig. 1. When the brush 1 is used to a set length, the controller receives a feedback signal of the linear position sensor 6, and the controller commands the mover 5 of the force motor 4 to retract so that the brush 1 is withdrawn from operation as the brush 1 is worn.

After the electric brush 1 (working electric brush) which is worn to a set length quits to operate, the standby electric brush (also provided with an electric brush current intelligent control system) automatically starts to operate, and the structure of the standby electric brush is the same as that of the working electric brush 1, so that the description is omitted.

When the linear position sensor 6 learns that the rotor 5 returns to a preset position, the controller disconnects the power supply of the force motor 4 to save electric energy, and meanwhile, if the force motor 4 has a power-off self-locking function, the rotor 5 is self-locked and limited by the force motor 4 and cannot freely stretch out and retract. If the force motor 4 does not have a power-off self-locking function, as shown in fig. 1, a self-locking mechanism is arranged on the mover 5, the self-locking mechanism is composed of a positioning recess 51 on the mover 5 and a spring pin 52 on one side of the mover 5, and when the mover 5 retracts to a preset position, the spring pin 52 is clamped into the positioning recess 51 under the action of elastic force to realize self-locking positioning.

As can be seen from the above, if the brush current intelligent control system is connected to each brush 1 of the generator, the current values of all brushes 1 in the generator can be controlled in real time, so as to prevent the occurrence of brush failure due to the serious non-uniformity of the current on the brushes 1.

As shown in fig. 1, a brush lifting mechanism 11 is disposed at the lifting end of the electric brush 1, the brush lifting mechanism 11 is made of an elastic material, the middle portion of the brush lifting mechanism 11 is connected to the mover 5, and the two ends of the brush lifting mechanism are movably connected to the concave holes at the lifting end of the electric brush 1, so that the brush lifting mechanism 11 can be separated from the lifting end of the electric brush 1 under the action of an external force (such as pinching the two ends), thereby facilitating the replacement of the electric brush 1.

It should be additionally mentioned that, in order to prevent the occurrence of a hydrogen explosion accident, a hydrogen sensor (not shown) may be disposed above the brush 1, and the hydrogen sensor is connected to the controller. Once the hydrogen sensor detects that the hydrogen concentration reaches a set value, an alarm signal is sent out, the lifting brush action is locked, the polishing brush and the arc extinguishing brush action are locked, and ventilation is enhanced to prevent hydrogen explosion.

The force motor 4 in the foregoing embodiment may also be replaced by a push-pull electromagnet, and the function of the shunt 8 may also be replaced by a hall current sensor 9, as shown in fig. 2, which is a schematic structural diagram of another embodiment of the intelligent brush current control system provided by the present invention, the push-pull electromagnet 7 preferably adopts a slow long-stroke (e.g., a solenoid type) electromagnet to output thrust to the mover 5, at this time, a spring 71 is generally required to be connected to the mover 5, and the spring 71 normally pulls back or pushes the mover 5 forward to provide a push-pull resultant force in cooperation with the push-pull electromagnet 7. Compared with the embodiment shown in fig. 1, the remaining structure and operation principle of the embodiment shown in fig. 2 are the same, and are not described herein again.

In addition, the force motor 4 has many alternative modes, such as an electric push rod, an electro-hydraulic push rod and a hydraulic cylinder, wherein the electric push rod or the electro-hydraulic push rod outputs thrust, and a hollow cup motor can be selected as a power motor of the electric push rod to realize rapidity of action and output flexible force in consideration of the fact that the electric brush works in a vibration environment; at this time, in order to absorb the influence of vibration, an elastic material (such as an elastic gasket) may be installed at the pulling end of the brush to form a buffer, and the rest of the structure and the operation principle are similar, which are not described herein again. In short, any controllable power device can be applied to the present invention.

In the two embodiments, the brush current intelligent control system is described by taking the brush 1 arranged in the horizontal direction as an example, in this case, the pressure between the brush 1 and the slip ring 2 does not change along with the change of the self weight of the brush 1, and the pressure control is simpler. The pressure of the electric brush 1 above the slip ring 2 is formed by adding the self weight of the electric brush 1 to the thrust of the force motor 4 (or the push-pull electromagnet 7 plus the spring 71); the pressure of the electric brush 1 below the slip ring 2 is formed by subtracting the self weight of the electric brush 1 from the thrust of the force motor 4 (or the push-pull electromagnet 7 plus the spring 71); the pressure calculation method of the electric brush 1 on the side surface of the slip ring 2 is different along with the different inclination angles; if the pressure values of the respective brushes 1 are required to be equal as much as possible, it is necessary to consider the arrangement position of the brushes 1 and the wear of the brushes 1.

The inclination angle of each electric brush 1 is unchanged in the using process, so that the influence of the weight of elements except the electric brush 1 on the pressure of a working surface is unchanged and can be regarded as a constant, and the influence of the constant can be eliminated by measuring influence factors in advance and adding the influence factors into control information of a controller; the weight of the electric brush 1 is variable, and the weight of the electric brush 1 changes along with the wear of the electric brush 1, but the weight of the electric brush 1 regularly changes along with the change of the length of the electric brush 1, so the controller can change the thrust of the force motor 4 (or the push-pull electromagnet 7 plus the spring 71) through the information fed back by the linear position sensor 6 to eliminate the influence of the variable, thereby realizing more accurate pressure control.

Since the brush 1 inevitably works in a vibrating environment, the sensors, the controller and the action mechanism will frequently sense, feed back, instruct and act, and in order to work the brush 1 in a stable state and avoid frequent actions of the devices, the thrust amplitude of the force motor 4 (or the push-pull electromagnet 7 plus the spring 71) should be adjusted in steps.

The intelligent control scheme of the brush current is a comprehensive scheme. The invention can also adopt a simplified scheme for controlling the brush current, and only comprises the following steps: controller, power motor, carry brush mechanism and current sensor.

The pressure that the power motor applyed to the brush is the not adjustable constant value (just as the constant pressure that constant pressure spring of prior art applyed to the brush is the same), and current sensor also only sets for a feedback information, and is brush "electric current super large" information, feeds back to the controller, and the controller instructs power motor "move back the brush" (the controller sets for moving back the brush total number), and this simplified scheme can withdraw from the operation with the electric brush of electric current super large to avoid the emergence of brush burnout accident, realize protect function.

The invention can be considered to realize single function, partial function and comprehensive function according to the requirement in practical production and specific application.

The invention also provides an intelligent control method of the brush current, which is used for realizing automatic regulation, control and protection of the brush current:

if the current of a certain brush is overlarge (the current value is more than or equal to 2 times of the rated current of the brush): the protection action is directly 'brush withdrawing'; the method is a non-time-limit protection measure, but the method is allowed to be subjected to 'forced excitation action locking' -forced excitation action, and the original electric brushes with overlarge current and overlarge current can reach the direct 'brush withdrawing' action setting value of the electric brushes with overlarge current, so that the possibility that the forced excitation action and the direct 'brush withdrawing' action of the electric brushes with overlarge current can act simultaneously is caused, and therefore, the direct 'brush withdrawing' action of the electric brushes with overlarge current is allowed to be subjected to the forced excitation action.

If the current of a certain brush is too large (the current value is more than or equal to 1.5 times and less than 2 times of the rated current of the brush): the pressure of the electric brush is gradually reduced until the pressure lower limit set value is reached, the current still can not be recovered to the normal range after three times of brush lifting and operation, and the state to be judged is lifted (control measures).

If the current of a certain brush is larger (the current value is more than or equal to 1.15 times and less than 1.5 times of the rated current of the brush): the brush pressure is gradually reduced until the pressure lower limit set value is reached, and the brush current is restored to the normal range through pressure regulation (regulation measure).

If the current of a certain brush is small (the current value is less than or equal to 0.5 times and more than 0.25 times of the rated current of the brush): the brush pressure is gradually increased until the pressure upper limit set value, and the brush current is restored to the normal range through pressure regulation (regulation measure).

If the current of a certain brush is too small (the current value is less than or equal to 0.25 times of the rated current of the brush): gradually increasing the pressure of the electric brush until the pressure reaches a set value of a high limit, and lifting the electric brush for three times (with a set time limit) until the current still can not return to a normal range after the electric brush is put into operation, and lifting the electric brush to a state to be judged (control measure).

The setting value, besides the current, also has setting time limit (such as selection between 0.1 second and 60 seconds) to prevent the control device from frequently acting.

Carrying out the three-time brush lifting: the first time is carried and brushed for 2-10 s, the second time is carried and brushed for 5-30 s after the interval is set for a long time, and the third time is carried and brushed for 20-120 s after the interval is set for a long time.

The burnout accidents of the electric brushes are all burnout by large current and electric arc, and in the process of burnout development, all electric brush currents are approximately equally divided into individual and small electric brushes to concentrate the currents, namely the phenomenon of concentration is a form, and the essence is that the phenomenon of current rush occurs, and the electric brushes cause self burnout due to the current rush.

The prior art continues to deteriorate and develop by artificially adjusting and controlling the current robbing phenomenon, and has the limitations of artificial adjustment and control: (1) the seedling head of the current robbing phenomenon can not be found in time; (2) pertinence and timeliness are difficult to realize, and the technology of each person is greatly different; (3) the human body danger exists in artificially treating the electric brush which is deteriorated and developed; (4) it is difficult to realize effective prevention and cut-off of the accident chain.

Intelligent regulation, control, protection:

omnibearing, full range and whole process: each brush (multiple parameters: current, temperature) is monitored in real time without interruption.

Such as current, from too small, too large, all the way through (concurrent signaling and showing the specific number of the brush).

The invention aims at different running modes of the generator, and has different control modes on the brush current.

(1) The generator is started and stopped:

the method is characterized in that when the excitation current of a generator is 35% or less of the rated current in the starting and stopping processes of the generator, although brushes 1/5-1/3 are sequentially brushed off in the running brush according to the light-load brushing off running mode of the generator, the running brushes are still mostly in a state of small current, the pressure of the running brushes is set to be a low limit value at the moment, and regulation and control are not carried out, namely the starting and stopping modes of the generator are that the pressure of the brushes is regulated and controlled by locking the excitation current.

(2) The generator light load mode:

the method is characterized in that the generator runs under light load, namely when the exciting current of the generator is 35-60% of rated current, the phenomenon of overlarge current deviation of a running electric brush is considered, the pressure of the electric brush is allowed to be adjusted to a certain extent, the adjustment extent range is that the starting adjustment pressure is the low limit value of the pressure of the electric brush, and the pressure increase value extent range is that the high limit value of the pressure of the electric brush is subtracted from the low limit value of the pressure of the electric brush and then multiplied by 80%.

(3) The normal operation mode of the generator is as follows:

the invention refers to the normal load operation of the generator, namely when the excitation current of the generator is 60% or above of the rated current, the invention enters the normal mode of regulating, controlling and protecting the brush current.

The intelligent control method for the brush current provided by the invention has the following operation sequence when the brush is in an emergency: when a certain brush has overlarge current and is removed, and then a certain brush has overlarge current and is removed, namely the condition that the current of the subsequent brush is overlarge when the current reaches the previous time, the operation sequence of the emergency brush is as follows: the electric brush is used for judging whether the current of the electric brush is still too small or not.

In the following embodiments, if necessary, one set of device for controlling the polishing brush and the other set of device for controlling the arc extinguishing brush are respectively added on the running track of the electric brush, and the electric brush is automatically put into operation as required. The polishing brush is also called a descaling brush and a grinding brush, the material and the structure of the polishing brush are the prior art and are used for polishing bad film layers on the sliding working surface of the slip ring electric brush, the material and the structure of the arc-extinguishing brush are also the prior art, and the typical structure of the arc-extinguishing brush is an arc-extinguishing brush disclosed in Chinese patent application No. 200710003579.7.

The intelligent control method of the brush current provided by the invention can be implemented by combining the average current comparison of all rows of brushes (a polishing brush and an arc extinguishing brush are additionally arranged on the running track of the brushes):

when the average current of a whole row of brushes is larger than that of other rows of brushes (for example, more than 150% of the average current of other rows of brushes), the brushes are operated to polish and extinguish arc brushes, the oxide film is processed (after a set time limit is passed), and the brushes with larger current in the rows of brushes are processed step by step, namely, the brush pressure is reduced. Until the deviation of the average current of the row of brushes relative to the average current of other rows of brushes is within a specified range.

When the average current of a certain row of brushes is smaller than that of other rows of brushes (for example, less than 50% of the average current of other rows of brushes), the brushes are operated to polish and extinguish arc brushes, the oxide film is processed (after a set time limit is passed), and the brushes with smaller current in the rows of brushes are processed step by step, namely, the brush pressure is increased. Until the deviation of the average current of the row of brushes relative to the average current of other rows of brushes is within a specified range.

When the sum of the average currents of all the rows of brushes is checked, the number of the brushes actually running in all the rows is considered.

The intelligent control method of the brush current provided by the invention also considers the control of the brush running temperature:

(1) a small hole is drilled in the surface, which is properly installed at the bottom end (close to the end of the sliding ring) of each brush holder 21, within the range of 1-5 mm away from the bottom end of the brush holder 21, a point type temperature sensing element (temperature sensor 22) is installed to measure the temperature of the electric brush body close to the sliding working surface, and a temperature signal is transmitted to the controller through the temperature sensor 22.

(2) The reason why the temperature of the sliding surface of the brush is high is: dry friction, brush holder shunt, brush current is too large. The sliding operation working surface of the graphite brush reaches 140-155 ℃, and the oxidation film is damaged at high temperature, so that the sliding operation characteristic is deteriorated.

(3) Setting the temperature sensing element to be 'brush withdrawing' at 135-140 ℃; the temperature sensing element is set to reduce the pressure at 115-135 ℃, and if the temperature continues to rise, the brush is lifted to be checked.

(4) The temperature of a certain row of electric brushes is generally too high or too low: the polishing brush and the arc extinguishing brush are put into operation simultaneously or sequentially to form a good oxidation film layer.

The intelligent control method for the brush current provided by the invention also considers the light-load brush reduction operation condition of the generator:

at present, a generator set runs on a slip ring all the time no matter how many brushes are installed, and all brushes run under any condition from starting, light load, full load to forced excitation action. Especially, the current density of the electric brush is too small when the electric brush is in a low valley and under light load at night, which is unfavorable for a plurality of indexes of the electric brush operation, and simultaneously wastes the electric brush and abrades the slip ring.

When the light-load exciting current of the generator is 60% or less of the rated current, the brushes 1/5-1/3 are set to be successively reduced to operate, the number of the brushes in operation is determined according to the exciting current, the brushes are put in and out at any time, and the reduced brushes are successively put in operation (namely, the number of the brushes in operation is positively correlated with the magnitude of the exciting current) along with the increase of the load of the generator.

The brush reduction operation action setting condition can be selected from the following sequence: (1) brush reduction according to the number; (2) starting to reduce the brush from the high-current brush; (3) starting with a low current brush; (4) the brush is decreased from the brush with the high temperature.

The intelligent control method for the brush current provided by the invention has the following steps of:

the logic analysis part in the controller compares the sum of the currents of all the electric brushes with the total excitation current according to the set time, if the deviation is larger than the set allowable range, the brush lifting program is started, the brush is lifted for three seconds, the comparison difference value between the sum of the currents of all the electric brushes and the total excitation current is calculated when one electric brush is lifted, when the difference value of the lifting time difference value of a certain electric brush is obviously reduced (for example, when the electric brush is lifted, the change of the sum of the currents of all the electric brushes exceeds 5 percent or even 10 percent), the brush holder is seriously shunted, and a computer informs a person on duty to handle or withdraw the electric brush.

There are three implementation schemes proposed for reference selection due to brush holder shunting: (1) lifting brushes according to the installation and use serial number sequence; (2) brushing according to the temperature sequence; (3) and (4) carrying out brushing according to the current magnitude sequence.

The intelligent control method of the brush current provided by the invention also considers the brush vibration (for this reason, a vibration sensor 55 is arranged on the extending end of the mover 5 to measure the vibration of the brush 1, and a polishing brush and an arc extinguishing brush are additionally arranged on the brush running track):

the fluctuation of the friction coefficient, the non-uniform current and the fluctuation cause the vibration of the sliding operation of the electric brushes, if the vibration of one row of the electric brushes reaches a set value in the initial stage of the vibration, the bad oxidation film (no film, non-uniform and bad film) is indicated, and the polishing brush and the arc extinguishing brush act to eliminate the vibration in the sprouting stage.

If a single brush vibrates, but other brushes in the row do not vibrate, the brush has a problem and moves back.

In the above intelligent brush current control method, the control relationship among pressure, current and temperature is as follows:

the pressure and the current have upper and lower limit set values, and the temperature has an upper limit set value: the pressure upper limit, the lower limit, the current upper limit, the lower limit and the temperature upper limit, wherein five set values are respectively controlled, when a single parameter is controlled, any one parameter reaches the limit value, and the electric brush is to be checked.

The above-described "forced action" means:

(1) the 'forced excitation action' is the requirement of the abnormal operation state of the main equipment, the exciting current reaches 1.5-2.5 times of the rated current during the 'forced excitation action', the action time limit is generally 10 seconds, and in the process, a plurality of electric brush currents can be greatly increased.

(2) When the power is on, all the emergency backup brushes are put in.

(3) Locking by a forced excitation action: when the brush is in the forced excitation action, the regulation, control and protection action program of the brush current is locked by the forced excitation action under the normal condition, and the brush lifting and the brush withdrawing are not permitted.

(4) When the force excitation acts and the set time delay limit, the blocking temperature is high, and the brush is lifted and retreated.

(5) After the strong excitation action: the electric brushes are not restored to the original states of standby and quit operation, but in a new operation state, the electric brushes needing to quit operation after strong excitation large current impact damage are judged again, when the electric brushes quitting operation reach a set quitting total number, the electric brushes do not quit operation any more, the electric brushes quitting operation originally are only used as emergency standby electric brushes to be put into operation due to 'strong excitation action', the electric brushes can not quit operation any more, only a reminding signal is sent to ensure that when the total number of the electric brushes are in operation, after the electric brushes damaged by strong excitation large current impact are replaced and put into operation, the electric brushes quitting operation originally can quit operation and replace new electric brushes until all the electric brushes are restored to normal states.

(6) After the "forced operation" process is finished, since the oxide film may be destroyed by a large current, the oxide film is treated by a polishing brush or an arc extinguishing brush at a predetermined time limit.

The invention has the following cautions when the small motor is applied:

the small-sized motor has the advantages that the number of the small-sized electric brushes with small current is small, all currents can be borne by one electric brush, the sequence of processing the abnormal conditions of the electric brushes needs to be considered in intelligent control, the electric brushes with small current and low temperature are processed firstly, and the electric brushes with large current and high temperature are processed after the electric brushes with small current and low temperature carry current normally.

The foregoing description is intended to be illustrative rather than limiting, and it will be appreciated by those skilled in the art that many modifications, variations or equivalents may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The utility model provides a brush current intelligence control system which characterized in that: the electric brush power measurement device is characterized in that a force sensor is arranged on the lifting end of each electric brush, each force sensor is connected with a controllable power device, the controllable power device transmits thrust to the electric brush through the force sensor, the force sensor is connected with the controllable power device through a controller, a current loop of the electric brush is connected with a shunt or a Hall current sensor and used for measuring the current passing through the electric brush, and the shunt or the Hall current sensor is connected with the controller;

when the measured current on the electric brush exceeds the upper limit value, the controller sends out an instruction to reduce the thrust output by the controllable power device until the current on the electric brush is lower than the upper limit value; on the contrary, when the measured current on the electric brush is smaller than the lower limit value, the controller sends out an instruction to increase the thrust output by the controllable power device until the current on the electric brush is higher than the lower limit value.

2. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system according to claim 1, and the intelligent brush current control system is characterized in that:

3. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system as claimed in claim 1, and a polishing brush and an arc extinguishing brush are additionally arranged on a running track of the brushes; the method is characterized in that:

4. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system according to claim 1, and the intelligent brush current control system is characterized in that:

if the temperature measured by the temperature sensor reaches 135-140 ℃ or even higher, the corresponding electric brush is withdrawn;

and if the temperature measured by the temperature sensor reaches 115-135 ℃, reducing the pressure of the corresponding electric brush.

5. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system according to claim 1, and the intelligent brush current control system is characterized in that: comparing the sum of the currents of all the electric brushes with the total exciting current, if the deviation exceeds the set allowable range, starting a brush lifting procedure, namely lifting the brushes one by one, and when one electric brush is lifted, calculating the comparison difference value between the sum of the currents of all the electric brushes and the total exciting current, and when the difference value is obviously reduced when a certain electric brush is lifted, informing a person on duty to handle or withdraw the electric brush by a computer.

6. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system as claimed in claim 1, and a polishing brush and an arc extinguishing brush are additionally arranged on a running track of the brushes; the method is characterized in that: a vibration sensor is arranged on the extending end of the rotor to measure the vibration of the electric brush;

if the vibration of a certain row of electric brushes reaches a set value through measurement, the polishing brushes and the arc extinguishing brushes of the row act to process the oxide film; if a single brush in a row of brushes vibrates, while the other brushes in the row do not, the single brush is destacked and disposed of.

7. An intelligent brush current control method, wherein each brush of a generator is connected with an intelligent brush current control system according to claim 1, and the intelligent brush current control system is characterized in that: when the exciting current of the generator is 60% or less of the rated current, the brushes 1/5-1/3 are sequentially reduced to operate, and the number of the brushes in operation is positively correlated with the magnitude of the exciting current.