Aleksey Danilov

Saved 1 week 2 days ago to Repair and installation

Differential protection  See details »

 
Video subtitles:
  • 00:00: and again, Hello dear brothers Electricians today we have an interesting a voluminous theme called differential protection First let's talk about what to do I represent myself and then I will analyze separate elements of electric network which can be protected so here way and consider individual features of this type of application protection for them, and so the general case
  • 00:31: differential protection for understanding The essence of the process 2 of the current transformer between which is the protected circuit section conditionally draw a cable line about soldier you current generally has the same ratio of transformation then it will be clear that there are more complex cases we will start with a simple secondary windings of these transformers current are included in the difference of currents i.e.
  • 01:03: Meetings on what you end up getting for effect if a short circuit is outside the protected area of the current rack winding of current transformers in relay which is drawn here are subtracted and since they are equal between are subtracted completely 0 if the short circuit is on protected area
  • 01:35: whether it is from extraneous food has and he has a third-party diet indifferent are added and in the end we get on or sufficiently large current which This leads to its triggering operating principle core of this protection further start Nuances of features that this protection more and more complicate and try I now so tell that these
  • 02:05: Complications did not come all at once went patches obviously quietly start with this just simple example and where you saw current transformers which are exactly the same and coefficient of transformation transformation ratios current transformers in the general case, at least slightly differ and this slightly on high currents at short currents closures that are greater than the nominal current transformer they are originally here These are just a little contributes
  • 02:37: a significant mite as a result is obtained some small unbalance current in or which, with an external case, can lead to the fact that the role of c works because of this unbalance current relay setpoint differential protection round off not to do it applies some tricks, for example current transformers order special ones that are manufactured
  • 03:07: in pairs are adjusted to one another in principle case quite rare in the main Does not use other tricks the very first of them setting The unbalance current is simply rebounded folds further on specific examples it will be seen the second example use of special relays that this unbalance current is removed The unbalance current can also occur in
  • 03:40: some other situations, for example, yes even if you do not consider cable line out to be the same for example the same tires decay device or relay generator is in one place and transformers current elsewhere and length connecting cables It connects them somehow it does not equally and at sufficiently high currents this can be significant therefore
  • 04:11: the length of the stone line must also be taken into account not always they can be made identical purely constructively pure arrangement of elements Well, well, I drew cable line let's cable line and start with a cable line is not so simple to reverse attention cable has a very large length to implement this is the scheme as it is drawn
  • 04:41: and in three phases you need an extra cable which will connect protection and here and there, from one end to the Another plus a current relay will be needed another one to disconnect the line from two parties are even permissible in order to disconnect only on the supply side when one-way power is still far current transformer works at a very high resistance
  • 05:11: load of control cable and therefore directly implement this Here is such a scheme of differential of protection longitudinal as it is also called because that current transformers are located along the line and along the current of the short circuit. the supposed It is unrealistic for this to go to tweaks and so such a seemingly simple defense
  • 05:41: changes the algorithm of its work and turns into a whole panel, and even in 2 located on one side cable line to the other and one of the so to speak the series 1 of the series of these panels called up differential line protection this name has already been avoided because such protection and call for already for a long time and here in brief what
  • 06:12: the problem it solves firstly we do not it is advantageous to send a signal to strings of windings current transformers with three phases is too turns out for this make such a trick and here under such this formula is converted these signals are these currents 1 AC the same thing happens on opposite end
  • 06:44: why then the connecting cable he It remains without no escape for vayfayu such signal has not yet learned While transmitting further along these wires connecting that is, two wires circulates these two signals from two In this case, way that the goats inside the line all on the contrary the signal is the current minimum order
  • 07:16: outside the current line , these here with the coefficients already and the signal the maximum signal in the line is obtained is sent from current transformers directly and through the separation transformers i.e. in this way the current transformer nourishes a rather modest load primary winding of this transformer Racket go there plus this one and galvanic separation is ensured and
  • 07:48: not that there was going to line The current transformer is not affected, but in lines can occur in particular orders of cables that lies as usual somewhere in parallel nearby from the differential control cable can be sufficiently serious impulse overvoltages with which already fears a separate part scheme I warn at once such protection complex enough so
  • 08:19: saw bears the character of a review i I tell only the main theses moments and existence in this way we have line with circulating currents so their they call it circulating alternating current which varies in depending on the presence or absence short current horse and where this closure is located device has a differential relay which from the current relay significantly
  • 08:51: it is different that this will apply in such a simplified scheme just which I showed and here it was tricky roles with a working and braking winding which switched to different values of operating winding up is turned on via rectifier bridge voltage which did not exist, that is, this voltage variable driving straightened and
  • 09:22: goes there the brake winding turns on to a signal proportional to the current in the line respectively, if the line rises current and I said before that with external goat current rises then the braking winding flowing with this current and relay is not The braking windings on or always done in order for the appearance on them of some magnitude or even there increase increased set points relay operation or in general
  • 09:55: blocked work if case is in range differential protection then circulating currents decrease accordingly braking the winding allows working or a plus increases the alternating voltage which goes to the working winding the relay is triggered that's how it is in this way and such same story on both the floor kits that
  • 10:25: one that on the other they are absolutely are identical except for one thing I'll talk about this protection is very fast acting works trouble-free absolutely to ensure Uninterrupted operation of protection in the event of some breakages there about the wolves or any damage to the connecting cable is usually made switches that take and
  • 10:56: switch both half sets on Spare wires with cable can happen Anything about this just further what problems can happen in electrical engineering with control cable elementary breakage of veins and collapses that this stops the circulating current The second closure lived on the ground than it is dangerous to wait for 2 closures and hi sailed and a short circuit
  • 11:30: between veins also leads to a full ndidi capable In order to ensure that all these parameters to control online always be aware of events if that happened on one of the floor kits a monitoring device is usually made The control device already uses such a principle of connecting cable In addition to the variable component,
  • 12:03: be constantly and they interfere with each other will not be absolutely theoretically possible Anything else there for the signals on knead the main The constant is easy to divide so there is added more circulating current constant now understand why on the same floor with 2 it would generally be something unreal with one sex set is served constant current and then the value of this when commissioning is strictly fixed if
  • 12:33: that in this chain has changed the trouble I further in a chain where a constant you can always organize a measurement insulation resistance is relatively land this principle hypothetically, too, everything is decided only this process Automate that in the event of a breakdown blocked the protection function
  • 13:06: in the case of some other violations just operational staff was either timely notified of this or to impeach him push the button and watch the readings in principle, this is the protection See here is such a simple shot at attempt to implement it professionally flies here in the whole panel well this probably the most of complex such protections are therefore dismantled we go further from the longitudinal
  • 13:38: differential protection is not superfluous would go to the width well, as I already here stuttered it is longitudinal when current transformers are installed along current flowing along the line or along the protected area or something like that in mostly everything differential protection most of them part including transformers generator is not longitudinal, but is and transverse and that's how it is implemented
  • 14:08: transverse protection we have a cable line consisting of two parallel to routed cables cable requirements they are the same there is the same brand of the same section, respectively, have the same their characteristics and resistance and so on, the cables at one point start at one point end at each cable on the side where protection is available current transformers for construction
  • 14:38: longitudinal differential protection with the same phases of this cable current transformers in the secondary winding are again connected by the difference of the currents what happens next when passing through cable line of rated currents since the resistance of these lines the same currents are distributed over them half-and-half a dream that the natural error the same current yields on the secondary
  • 15:09: windings the same current is the only one that it is on of similar phases is subtracted so to speak himself out of himself and it turns out that in the role of differential we have zero the same will happen if there is a short circuit behind this line that is, somewhere beyond the load, that is then a short circuit will also run through these lines split in half and principle with
  • 15:39: certain error nothing which will be where the balance of the furnace from which it will be necessary to rebuild a as I said before standard version with no current balance These are different current transformers of which the same does not always exist Here still it is added that that lines speaking or not this can be a little bit different is not always like that all is identical If a short circuit occurs on the one of the cables
  • 16:11: This line of distribution current will change through the current transformer which will be to feed the damaged line will be flow the lion's part of this current the current in the winding will change accordingly relay and relay will tripped switch The only problem with such protection and zone is not limited to the final The point where these cables converge into one again
  • 16:42: she finishes early for it that further than were closer obtained goat by the end of the line the greater currents These shoulders begin to equalize because that the short man still eats one by one line and on the other line and here It will be very difficult to separate them and if try to do it then we just We rest on the unbalance current which will be hinder us to do it by limiting sensitivity
  • 17:14: differential protection, and any which plus is differential protection automatically displayed when outputting to one of the cables of this protection vaymont so god contacts cable and connectors The work of this defense is involved only one cable is disconnected automatically next we smoothly go to differential protection of power transformer
  • 17:46: which in principle for many is the most relevant what does differential protection look like? 2 winding transformer to start with they start the current transformer is put on the high side of the current transformer low side and now here draw it like this, let's imagine that the transformer has a coefficient transformation is one and decreasing which does not merely increase the separation
  • 18:17: problem with differential protection transformer a remain as cable line that is, and even if it is transformer ratio of 1 then this inequality of transformation coefficients times avatar current when we transform transformer under tension at least for idling on the primary the current flows briefly magnetization
  • 18:50: which for some time exceeds the nominal value at the secondary The winding of this current is not even if it connected to the consumer therefore on the face factor for triggering a differential protection when the transformer is switched on that is, there is inrush current to build up and in some cases, even if they are already under with a rated current transformer
  • 19:20: there are times when one of the windings then all the same what is that is, it is not only when turning on such a problem reveals why from this problem it is necessary rebuild naturally on differential protection the easiest way is to put an excerpt in time, that is, there will already be around and a difference this protection with time delay and independently and here principle of time this existence of this process
  • 19:51: magnetization is known from it can be will be rebuilt but in this way we are deprived certain charms of this differential protection is instantaneous actions and all actually try to be carried out instant action for some exceptions, but when we introduce We try to take the time stovochku which will be minimal possible that is just such a current
  • 20:23: choose at which here in general sensitivity of protection do normal we can do and instant time, but then you must to rebuild the magnetizing current take the set-point more differential or such and then this such a thing will be called a cut-off thus the power transformer there are two types of differential protection differential cutoff and
  • 20:55: differential current protection with time delay these two protections implemented in the terminals for which designed specifically to protect transformers and so stop distinguishing current figured out and what's next and next it turns out that the current load on the high and the low side of the power transformer not equal to each other, they are different to coefficient of transformation Only need to adjust transformers current in such a way that this this trouble
  • 21:28: somehow align on the side on the secondary so that the currents are the same when passing through current through transformer is not so this problem is not so easy to solve and not we always have the same This is the transformation ratio of 253 per drink 258 at 50-60 for 5 in any way that is we we have a standard ruler current transformers without which you need pick up something coming and if we
  • 22:00: select the closest option, it turns out that the unbalance current resulting from the selection ours is often very sound can surpass all possible only no balance is associated with inaccuracies length of connecting wires there and so further, and therefore this is the whole thing you need somehow in size to call I specifically speak for the size of the fact that further it will be more interesting
  • 22:31: for this you can apply either a level The some transformers in the chain of these current transformers or apply special relays that switching from finger to finger winding will help us accomplish this we will not lose sensitivity protection from this other than balance caused by the selection of coefficients
  • 23:02: transformations We will only have amaters be built up by increasing deep protection settings and the next problem is related to the fact that Generally speaking, the schemes for including primary and secondary windings of transformers power they differ from each other rarely you can stand and transformer the power whose star is a star but it happens then there are no problems, but if it is triangle star and if this is 3
  • 23:32: winding transformer in which side 110 kilovolt star on the side 35 star on the side of the hexagon to in the end we do not get 3 winding at least on two-winding we will look and at between primary currents in The same phase is obtained by shifting the angle between secondary currents as well as the primary result of this
  • 24:03: By folding these two currents they are postponed naturally a vector on we get some unbalance current which is already provided with a difference not the angles between these currents and if in nominal mode as any of the currents unbalance, it does not have a significant influence on the relay winding, then with external ring he can have so far and what A significant role can be played by something
  • 24:33: It is necessary to do with this and there is a small a trick that allows you to do this simply elementary without any superfluous hardware sensations associated with installation of some say whether moving transformers there so on all very much just on the transformer side where the winding power pork in a triangle The current transformer is connected by a star and A scheme is sent to the def shield on the side
  • 25:03: where the power rim is a blue star conversely in the triangle and in the dip then there is a reverse Also applies to such winding where the star there is triangular where the triangle there is a star in this case all absolutely no angled alignment shifts between like currents are not It is because each of these deserves a separate film then I I will not tell you in detail how
  • 25:34: does the mt and that which is just carrying out and aligning all these here these things transformation ratios in particular and solving many other problems particular detuning from the periodic component of the short-circuit current This is a separate topic for individual films we are still not all pretty have now disassembled the most interesting soon go to make an allowable too
  • 26:06: differential protection and not to mention the synchronous generator is I think it's also blasphemous although this type of differential protection can be places even easier than power transformers here is one An interesting feature of the generator is quite a powerful machine and we are now we will speak capacities over 1 megawatts and all that is lower it may not
  • 26:37: to defend differentially all that is higher he may be absent differential protection if not available special current transformers or their the possibility of installing in zeros generator generator connects to 1 pet device through the bus it is clear that over 1 megawatt stone line is so then not serious and 0 generator is not
  • 27:09: joins in this case as Oy electric motors are somewhere inside it also connects from outside also tires and in this zero too have current transformers in that number go to the defense and the second set of avatars only is already sung device in the area of ​​the rules of the bus connecting the generator with
  • 27:40: switchgear are switched on into the range of differential protection and then all the same cable from there cable from here food de file leakage protection time delay 0 here is the disadvantages of the problem where protection is about the same is not the same current transformers due to which can
  • 28:10: unbalance current and cable lines due to which this is the current of unbalance too, can arise and what can arrange need to get settled and the generator protection is always executed in three-phase design if any spoke on the cable line In principle you can get rid of you and nothing problems but may not be there but to protect the generator specifically current transformers are used
  • 28:42: installed in all three phases here there is one cunning here in this area can there is a ground fault and somewhere on the same tion of the same substation is a little farther behind can In the second phase, land and this regime is also for generator are dangerous because it is also the most between phase closure but it distributed such it turns out go in protection of three-phase generators
  • 29:12: This situation is considered as a goat in the zone and the generator turns it off as a generator Our sightseeing tour has already reached bus tires can also be protected differential protection to and can exist in two hypostases complete and incomplete full differential protection The tire includes current transformers all the elements that are rolling to the tops connected corresponding to feed and waste
  • 29:42: respectively, the inclusion of transformers current of secondary windings should be to stop the power supply elements you read out in this case when external short circuits. Protection I work with a failure in the zone actions are limited to these current transformers installation protection works on disconnection incomplete differential protection of tires includes only the elements that
  • 30:13: these tires nourish and most powerful Included in this case from all other elements their currents must be rebuilt moving Further and now we will consider differential protection that accept eggs of ordinary n 110 kilovolts and above here how not to install current transformers than their unconnected among themselves what cables it is Unreal task because in the same
  • 30:44: cables if they are suspended under lines 110 kilovolt is already the voltage from this lines of 110 kilovolts and nowhere from this to escape therefore here a very interesting feeling was invented which is associated with circulation additional signals by the very lines on their sell well, principle as in protection ripened only a little bit The construction is more complicated and the algorithm of work slightly different for this on two ends
  • 31:15: line It is set in the so-called h transceivers that generate certain impulses on a certain frequency transmit them in line and the same impulse and immediately accept their own and someone else's transmitter of his own from the transmitter strangers in order to not be allowed to enter receiver a huge amount of voltage 110 thousand volts frequency 50 hertz the so-called communication capacitors
  • 31:45: signals it transmits much better But for 50 hertz he is an insurmountable obstacle to further allocation of a useful signal and matching ios in wave resistance of the connecting coaxial cable serves as called a filter on and connections usually it is installed on one portal with communication capacitor for work on the filter and connection lower lining capacitor is capable of grounding when
  • 32:15: help the switch that is installed there same on the portal in order to hope signals were distributed only along the line and did not climb further into the power grid on portals is set so called a barrier filter it is an inductance which is an insurmountable obstacle already for HH signals despite the fact that the connection is via a single phase wire in hours block or hang on all 3 a photo
  • 32:47: the husband is the signal because of the long line all equally penetrate to neighboring iii phase and so we have a communication channel formed by one of the line wires and land and before telling on it would be nice to evaluate it a little advantages and disadvantages but mostly disadvantages of dignity here principle everyone will be clear from further narration as any channel it is capable of interfering with the device that surrounds it and is capable of doing something about it
  • 33:18: perceive from interference that it creates get rid of the frequency at which a radio signal is being exchanged between my reception by transmitters from all other things sometimes I can not get rid of anything be this other well on the river are of different nature Firstly, it is the interference that is caused by switching voltages the network itself, despite that the fundamental harmonic is 50 hertz
  • 33:49: capacitors, but some compact switching input pulses reception of the transmitter still arrives as nor strange it affects the whole thing attenuation in communication channels which seemingly formed only some kind of wire and should not be on the idea change their resistance in broad bounds However, the propagation of radio waves is already Another completely history and fading in
  • 34:20: This channel is dependent on the weather conditions in general, that is, there is some kind of damp fog when scanning during This dampness can introduce some kind of interference wire icing occasionally leads to the fact that in h protection output and enter something in its place another similar functional action plus a considerable contribution to sustainability Such work of such protection is made by themselves
  • 34:54: short circuits which occurs both in the neighboring phases of which the radio channel is unorganized but more on that and on which there is although actually speaking protection protects against short-circuits that this it's easy enough to organize the default radio operation in this channel and consider this another regime that the first of the protection and will be implemented
  • 35:25: so the first one in the queue is directed Microwave leakage protection lock such a logic is installed on the panel Start-up kits for this protection are there is this about years like resistance which fixes the phase closure in the line, naturally, it has The direction of their actions and orders for back, it does not work, that is it years
  • 35:55: determines the first fact of availability emergency mode in the league and short closure and the fact that this is short closure somewhere in that side which she protects naturally the border of this protection blurry enough for guaranteed further is located than switch 2 on is that at the end of this line further
  • 36:28: there is still enough earth protection that is from azaz that there was a complete set here between Phase and now also a ground fault this protection is also the case to the there is a power direction relay that control which aims single-phase short circuit power or behind the phenomenon of the phenomenon we earn image, the model forms commands for that in the line there were goats and only there
  • 37:00: the same at the opposite end respectively you see at one end line protection which determines the direction of the case on the other They also had to somehow link them between to share a match results that the current in the line occurred instant shutdown without exposure time and this is the dignity of this protection and then where does the transceivers, they work themselves as
  • 37:31: rule is silent and periodically exchange signals controlling the health of each other in a malfunction naturally protection is removed from action and operational staff about this an appropriate alarm is signaled as soon as there is a short circuit the usual algorithm works in Chapayev transmitters, they are launched both Directly and spar signal into the line but how If directly the transmitter received a command from
  • 38:03: The panel on the fact that the goat is in protected area from her point of view he stops 2 transceiver if the case is protected zone too the silence of both poems stops transmitters is regarded as protected zone and issued to teams panel for instant shutdown if case is outside the protected area for one of the protection kits is for
  • 38:34: back and stopping at his the transmitter will be unoccupied because protection will not work behind your back when availability signal from at least one transceiver in the line protection is not there are some other protection in this way exorbitant seemingly complexity protection is very fast acting very quality and very good effective with the following protection option
  • 39:06: using the transceivers in the check and channel of communication on one of the thresholds of the line is a differential phase protection that we just They considered it as a relay principle and it is for some reason differential-phase we are phase that it compares the values phases between the currents at the beginning and at the end of the line as when current transformers
  • 39:36: included and phases this at both ends if we accept them conditionally and direction primary windings in to pay case the through line they have currents pivoted to the ends of the phase line Strict do not match are shifted somewhere on 180 degrees approx. And is there a line they coincide in phase uniquely Only it is necessary to collect once in
  • 40:11: a bunch because they coincide in phase but a few kilometers away from each other, then not one dozen at the moment when there was a gigantic the panel's start organ and then felt would be honored by the transmitter's signal modulated admissible positive half-waves current that goes off line that is here such a picture positive half-wave transmission sends a burst of momentum to the line
  • 40:44: from vici signal to negative half-wave he is silent nothing transmits on the opposite side of his the transmitter does the same in the end if these are not positive half wave coincide in phase that is external goats then we have such a continuous line of total signal in the communication channel receivers of transmitters perceive this
  • 41:14: picture and consider that case in the protected zone is not the same if the current phase of the match get another picture receivers accept and analyze a signal to switch off the line with both sides here in brief is differentially Phase protection of the line is how much I am of one spoke would be about one topic differential protection film
  • 41:46: consciously made a review to us so that show all its diversity and greatness further, if possible I will talk about these protection in more detail, indicating how to than get together how it works like circuit circuitry is implemented and so on and so forth until new meetings dear brothers electricians who are interested in we 'll see you again