RU2554635C1 - Method of determining remaining switching life of high-voltage switch - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: current value of the commutation current I_com and the current value of the commutation voltage U_com are fixed for each phase at each switching. The commutation current is reduced to a rated voltage as per the following formula: I_t=I_com·U_com/U_rated, where I_t is the current reduced value of the commutation current. The value P_t of the current remaining life is calculated as per the formula P_t=(I_t/I_{o rated})². The calculated value of the current remaining life P_t is added to the earlier accumulated life of a high-voltage switch P_a for each of the phases. The obtained value of the remaining life is compared with a switching durability resource P_s for each of the phases.

EFFECT: improving accuracy for the determination of the switch remaining life.

3 cl

Description

The invention relates to electrical engineering, in particular to electrical equipment installed in switchgears, and can be used in power plants, substations and other electrical installations.

The claimed invention relates to a priority area of development of science and technology "Technologies for creating energy-saving systems for transportation, distribution and consumption of heat and electricity" [Alphabetical index to the International Patent Classification in priority areas of science and technology / Yu.G. Smirnov, E.V. Skidanova, S.A. Krasnov. - M .: PATENT, 2008. - P.97], as it allows to increase the service life of high-voltage circuit breakers by taking into account real switching currents.

There are various methods for fixing the value of switching wear of switches and devices for the diagnostic system of high voltage switches, which require the installation of a variety of sensors, for example Mikheev G.M. Digital diagnostics of high voltage electrical equipment. Publishing house "Dodeca-XXI", 2008. - 304 p. Installation of sensors (contact, that is, on the switch case, or non-contact - next to the switch case), installation of equipment (wired or wireless) for transmitting and receiving a measuring signal, subsequent operation of the sensors - all this has its drawbacks, namely:

- the need for autonomous power supplies or original devices for energy conversion;

- making changes to the design of circuit breakers, which may require a full cycle of development work of their manufacturers;

- Installation of communications and data transmission equipment operating in conditions of high electric, magnetic and electromagnetic fields;

- the reliability and reliability of any technical system is inversely proportional to the number of elements included in this system, that is, decreases as the system becomes more complex;

- finally, the installation of sensors on the entire fleet of circuit breakers and their subsequent maintenance is associated with one-time and constant costs, the volume of which can be compared or even exceed the cost of the circuit breaker itself.

Known methods for determining the switching resources of circuit breakers, which also require special settings and can be used by manufacturers of circuit breakers, especially since they consider the on-off cycle, which is not difficult to operate in contrast to the on-off cycle during short circuits.

For example, a known method of fixing the switching wear of circuit breakers, implemented when operating the device according to the patent of the Russian Federation No. 2303271, IPC G01R 31/327, Device for fixing the switching wear of switches. / German L.A., Sharov A.V., publ. 07/20/2007.

A sign of an analogue that coincides with the essential features of the proposed method is the possibility of fixing switching wear (according to GOST R 52565-2006 "AC circuit breakers for voltages from 3 to 750 kV. General specifications", hereinafter simply GOST R 52565-2006, instead the term "switching wear" is preferable to use the terms "resource on switching resistance" or "residual resource on switching resistance") of switches, in which the analogue "time interval of discharge of capacitors is converted into a number pulses proportional to the switching wear of the circuit breaker. "

The disadvantages of the analogue method, from the point of view of the technical result, is that it does not allow to evaluate the real residual switching resource of the switch for the following reasons:

- firstly, because it is not shown how the resource is related to the number of pulses;

- secondly, it is not described how to get the value of the residual switching resource of the circuit breaker in operation;

- finally, tripping the circuit breaker during a short circuit and then turning it on (the “shut-off-turn” cycle, which is possible in operation with the operation of the reclosing equipment) leads to a more significant operation of the circuit breaker life than the “turn-on-shutdown” cycle of the short-circuit current. However, the analogue method does not take this into account, which leads to an error in assessing the switching resistance of the circuit breakers.

A known diagnostic system of a high voltage oil circuit breaker, implemented during operation of the device according to the patent of the Russian Federation No. 23237179, MKI G01R 31/327, H01H 33/68, Diagnostic system of a high voltage oil circuit breaker. / Bashkirtsev G.P. et al., publ. 06/20/2008.

In the method-analogue "system ... increases the reliability of the high voltage oil circuit breaker and increases its service life", in the inventive method, taking into account the residual life of high-voltage circuit breakers allows you to more accurately determine and increase the "resource of its operation", and more precisely - its service life.

The disadvantage of the analogue, from the point of view of the technical result, is that although the advantages of the analogue indicate the possibility of increasing the service life of the high voltage switch, neither the description nor the formula shows how to do this. The analogue correctly states that "in the closed state of the high-voltage contacts of the high-voltage switch, thermal power is dissipated on them, the value of which, according to Ohm's law, is proportional to the transition resistance and the square of the operating current. Deterioration of the technical condition of high-voltage contacts leads to an increase in their transition resistance, to an increase in thermal power and warm up the contacts. " This is so, however, the resource of the high voltage switch determines its switching resistance, and not the temperature of the contacts. In addition, the analogue, like the first one, requires the installation of additional auxiliary equipment, the costs of installation and operation of which are borne by the power grid companies.

The prototype adopted a method for determining the residual switching resource of the circuit breakers according to the patent of the Russian Federation No. 2489726, MKI G01R 31/327, Method for determining the residual switching resource of the circuit breaker. / Mussonov G.P., publ. 08/10/2013.

A sign of the prototype that coincides with the essential features of the proposed method is the purpose, since the prototype solves the problem of determining the residual life of the high voltage circuit breaker by fixing the current value of the switching current for each phase at each switching, calculating the value of the current worked resource of the high voltage circuit breaker, and calculating the value of the residual life of the high voltage circuit breaker circuit breaker.

The disadvantage of the prototype, from the point of view of the technical result, is that in emergency conditions the current value of the switching voltage is not taken into account when determining the residual switching resource of the high-voltage switch. In emergency conditions, the voltage at the time of switching U _com can be both more and less than the rated voltage U _nom , for which the used high-voltage switch is designed. That is, the power P _com switched at the moment of operation of the high-voltage circuit breaker, and therefore its resource, depend not only on the current value of the switching current I _com , but also on the voltage at the time of switching. Failure to take into account the current voltage value leads to an increase in the error in determining the switching resources of switches.

The expression for determining the switched power is

P _com = U _com · I _com ,

where I _com - the value of the switching current at different voltage values.

The voltage values at the time of switching U _com , as well as the current values of switching current I _com , are in practice recorded according to emergency recorders and relay (dispatch) services.

Given that the resource of the high-voltage circuit breaker is calculated for switched currents at rated voltage, it is necessary to recalculate (bring) the current value of switching current to that value that would be at rated voltage

P _nom = U _nom · I _tn ,

where I _tn is the value of the switching current at rated voltage.

We equate the expression for the switched power P _com and the expression for the rated power P _nom , that is, U _com · I _com = U _nom · I _tn . From here we find the current value of the switching current reduced to the rated voltage

From (1) it is seen that the current value of the switching current I _com will be adjusted depending on the voltage at the time of switching, and the calculation of the residual switching resource of the high-voltage switch will be carried out according to the value of I _t - the reduced value of the switching current to the rated voltage. This will avoid the error in determining the switching resources of the switches compared to the prototype.

The objective of the invention is to create an affordable simple technology for determining the residual life of high voltage circuit breakers based on data from emergency recorders and relay (dispatch) services without the use of additional energy-consuming and expensive equipment. This allows the operation to obtain the following results:

- reduce the cost of determining the worked and residual switching resource of the circuit breakers in operation,

- transfer high-voltage circuit breakers to a maintenance system based on an assessment of their actual condition, as more economical in comparison with a system of scheduled preventive repairs,

- to adjust the overhaul periods of circuit breakers on the basis of a more accurate determination of the spent and residual resources of high-voltage circuit breakers.

The technical result of the proposed method is to increase the efficiency and quality of determining the residual life of high-voltage circuit breakers, which allows you to more accurately determine its service life. In addition, an additional technical result is to obtain a worked switching resource of high-voltage circuit breakers during operation without installing additional equipment.

In the inventive method for determining the residual switching resource of the high voltage switch, including fixing the current value of the switching current for each phase at each switching, calculating the value of the current worked resource of the high voltage switch, calculating the residual life of the high voltage switch, the technical result of the claimed method is achieved by the fact that according to the invention simultaneously with by fixing the current value of the switching current I _com for each switching for each phase They fix the current voltage value at the time of switching U _com for each phase, bring the current value of the switching current I _com to the rated voltage of the high-voltage switch for each phase, according to the following mathematical expression:

I _t = I _com · U _com / U _nom ,

where I _t is the current reduced value of the switching current, A;

I _com - the current value of the switching current, A;

U _com - the current value of the switching voltage, V;

U _nom - rated voltage of a high-voltage switch, V,

the current value of the switching current I _t reduced to the rated voltage for each phase calculates the value of the current worked resource of each phase of the high-voltage switch P _t during this switching according to the following mathematical expression:

P _t = (I _t / I _{o nom} ) ² ,

where P _t is the current spent resource of the high-voltage circuit breaker during current switching I _t ;

I _t is the current reduced value of the switching current, A;

I _{о nom} - rated breaking current (term according to GOST R 52565-2006), corresponding to the type of switch, A.

The calculated value of the current operated resource P _{t is} summed up to the previously accumulated worked resource of the high-voltage switch P _c for each of the phases, the obtained value of the worked resource of the high-voltage switch is compared with the resource for switching resistance (term according to GOST R 52565-2006) of the high-voltage switch P _k for each of phases of a given high-voltage circuit breaker and, in case of equality or exceeding the obtained value of the worked resource P _{c of a} high-voltage circuit breaker for at least one of the phases above the set If the accumulated resource P is used _for the switching resistance of the high voltage switch, the decision is made to replace the high voltage switch, and if the accumulated value of the spent resource P _{from the} high voltage switch is less than the set resource P _to by the switching resistance of the high voltage switch, the residual resource P _{of the} high voltage switch is determined by the following mathematical expression:

P _o = P _to -P _c ,

where P _about - the residual life of the high voltage switch;

P _to - the established resource for switching resistance;

P _with - the worked resource of the high-voltage switch.

The technical result of the proposed method is achieved by the fact that in order to better determine the residual life of high-voltage circuit breakers, in addition to each phase, when switching a circuit breaker whose current exceeds I _nom , the value of the operating life of a high-voltage circuit breaker P _{t is} reduced by Δ ₁ :

,

,

where Δ ₁ - correction factor for low switching currents;

I _nom - rated current of the circuit breaker (term according to GOST R 52565-2006; this current is ten times less than I _{o nom} - rated current of disconnection), corresponding to the type of circuit breaker, A;

I _{o nom} - rated breaking current corresponding to the type of switch, A;

I _t is the current reduced value of the switching current, A.

The technical result of the proposed method is also achieved by the fact that in order to better determine the residual life of high-voltage circuit breakers, in addition to each phase when switching a circuit breaker, the current of which exceeds I _cr , the value of the generated resource P _t calculated by formula 1 is reduced by Δ ₂

,

,

where Δ ₂ - correction factor for critical currents;

I _cr - critical current - tripping current, which is greater than the rated current of the circuit breaker, but less than the rated tripping current, and beyond which the arc time increases significantly, A;

I _{o nom} - rated breaking current corresponding to the type of switch, A;

I _t is the current reduced value of the switching current, A.

In other words, the technical result of the claimed invention is achieved by taking into account specific operational data (the number of switching, switching voltages and currents in each phase), which can be obtained from relay (dispatch) services and / or from emergency event recorders, and the procedure stated in the method operating with specified data.

New significant features prove the novelty of the proposed method.

The prior art has not revealed signs that match the distinctive features of the proposed method, which proves its compliance with the condition of patentability "inventive step".

The method is as follows.

High-voltage circuit breakers come in various designs and types (vacuum, gas, gas, air, oil, electromagnetic) incorporating arcing devices of various designs and types. All high-voltage switches combine contacts that are triggered during switching, limiting the life of the switch. Therefore, the resource for switching resistance of a high-voltage circuit breaker, according to GOST R 52565-2006, clause.6.6.4, is set as P _to - the number of times the maximum switching current is switched off I _{о nom} , which is called the rated breaking current. In practice, I _t - the current reduced switching currents range from the rated current I _nom , at which the destruction of high-voltage contacts does not occur, to the rated tripping current I _{о nom} , at which the intensive destruction of contacts occurs. All the facts of switching on and off, as well as all current values of the reduced switching currents I _t in operation are recorded by relay (dispatch) services and special devices - emergency event recorders.

High-voltage circuit breakers in operation switch simultaneously all three phases (as if connecting three circuit breakers in one design), each of its phases transfers its own energy and, therefore, its current reduced switching current I _t . The method allows to determine the value of the worked resource and the residual resource for each of the phases.

The main reason for the breakdown of the switch contacts is the electric arc as a function of switched energy. Therefore, accounting for the worked resource and determining the residual life of the high-voltage circuit breaker should be based on the determination of the energy released in the circuit breaker at the time of switching. The energy W _t released by the current on one phase or on one pair of contacts when the high-voltage switch is turned off is determined by the expression

where U _com - voltage at the time of shutdown; I _com - the value of the disconnected current; t _d - arc time, according to GOST R 52565-2006 - the time interval between the moment of the onset of the appearance of the arc and the moment of its complete extinction in all phases when the BB contacts diverge, t _d is a characteristic of this type of high-voltage switch.

Using the relation U _com = I _com R arising from Ohm’s law, and also passing to the reduced value of the disconnected current according to formula (1), we transform expression (2) to the form

where I _t is the magnitude of the reduced value of the disconnected current;

R is the resistance of contacts and arcs, R is also a characteristic of this type of high-voltage switch.

At the rated breaking current I _{о nom} according to (2), the following amount of active energy will be released:

If the reduced trip current is n times less than the rated trip current, i.e.

then, substituting in the expression (4) the value of I _{about nom} from the expression (5), we obtain

Dividing both sides of equality (6) by n ² , taking into account formula (3), we obtain

Similar calculations can be made for the released energy when the high-voltage switch is turned on. The result obtained is described by expression (7). The difference will only be in the current notation of formulas (2) - (7).

From the expression (7) we see that the energy W _{o nom} allocated in the high-voltage circuit breaker when switching with the current I _{o nom} , and the energy W _t emitted in the high voltage circuit breaker when switching with the current reduced current value I _t , are related by the relation W _{o nom} / n ² = W _t , where n = I _{о nom} / I _t . From the relation (6) proposed in the method, it can be seen that the energy released when switching various reduced tripping currents I _t is ² times less than when switching the rated current tripping I _{about nom} . This means that the circuit breaker resource is consumed n ² times slower. In fact, the resource of the circuit breaker is consumed even more slowly, since the manifestation of energy is not additive, for example, a million discharges of 220 volts (discharge when the household circuit breaker is turned on) will not lead to such damage as one lightning of 220 million volts.

Since the installed resource for the switching resistance P _{to the} high-voltage circuit breaker is set by the number of times the maximum switching current is switched off I _{о nom} and one switching off of such a current leads to the operation (consumption) of one unit of the resource, the shutdown with the reduced current I _t is P _t - fraction (in the interval from zero to one) of the operation of the resource unit of the high-voltage circuit breaker or, in other words, determines the value of the current activated resource of the high-voltage circuit breaker. In the proposed method, for any shutdown or inclusion for each phase, P _t is calculated - the value of the current worked resource of the high-voltage circuit breaker according to the formula (I _t / I _{o nom} ) ² (or according to previously constructed graphs or tables according to the formula (I _t / I _{o nom} ) ² ) arising from the aforementioned energy ratio (7), and is summed up by the cumulative total for each phase. This cumulative total, in fact, is the worked resource P _c for each phase of the switch. For all switching operations, the calculated value of P _c for each phase is compared with the value of P _k , and if the condition P _c ≥P _k for any of the phases is fulfilled, then a decision is made to replace the high-voltage switch.

The residual resource P _о is defined as the difference between the installed resource by the switching resistance P _{to the} high-voltage circuit breaker and the obtained value of the worked resource P _s , that is, P _о = P _к -P _s .

An example of using the method.

For example, we give real data of three high-voltage circuit breakers for 220 kV of various types VVD-220B-40 / 2000HL1 (air), VMT-220B-40 / 2000UH1 (oil), VEK-220-40 / 2000U1 (SF6), for which manufacturers indicated identical parameters, namely, rated current I _nom = 2 kA, rated tripping current I _{o nom} = 40 kA. According to clause 6.6.4 of GOST R 52565-2006, the service life for the specified rated tripping currents must be at least 15 trips for each phase, let P _k = 15, that is, all switches are new. For ten trips with a switching current of 8 kA (four times the nominal), for any of the phases and at the current voltage value at the time of switching U _com = 210 kV, the reduced current value I _t calculated according to expression (1) , will be I _t = 8 × 210/220 = 7.4 kA, the calculated value of the worked resource of one trip, according to the formula proposed in the method, is P _t = (8/40) ² = 0.034, and the total consumption of the worked resource for ten shutdowns will be P _s = 0.034 × 10 = 0.34, which is equal to the consumption of the worked resource of one switching with a current of (0.4) ^1/2 × 40 = 23.32 kA, and not 80 kA with a simple arithmetic calculation, which would be two units of the resource. The residual resource calculated by the proposed method will be P _to -P _with = 15-0.34 = 14.66 outages in this phase.

With the given switching currents I _t lower than the rated current I _nom , the design of the high-voltage switch does not allow a stable arc to occur in time t _d , and the resource of the switch does not work. However, calculating by the proposed formula (I _t / I _{o nom} ) ² _, we obtain a certain value of the operation of the resource Δ ₁ , which we will call the correction factor for small switching currents,

.

.

To compensate for the error, it is necessary to reduce the value of the previously calculated worked resource P _s by Δ ₁ for each phase for any switching whose current exceeds I _nom . The mathematical record of the last sentence looks like this:

In addition, according to GOST R 52565-2006, the design of the high-voltage switch does not allow a stable arc to occur at some critical currents I _cr . The critical current is the tripping current greater than the rated current I _{nom of the} circuit breaker, but less than the rated tripping current I _{o nom} , above which the arc time increases significantly. When the given switching currents I _t less than the critical current I _cr , a stable arc does not occur, and the resource of the switch does not work. In this case, if the manufacturers of the high-voltage circuit breaker indicated I _cr in the passport, then instead of using the correction factor Δ _{1, the} value of the previously calculated worked life should be reduced by Δ ₂ , which we will call the correction factor for critical currents,

for each phase for any switching whose current exceeds I _cr , that is

The residual life P _{about the} high-voltage circuit breaker is determined by the following expression:

P _o = P _to -P _c ,

where P _about - the residual life of the high voltage switch;

P _to - the established resource for switching resistance;

P _c is the spent resource of the high voltage circuit breaker.

Claims (3)

1. A method for determining the residual switching resource of a high voltage switch during operation, including fixing the current value of the switching current for each phase at each switching, calculating the value of the current worked resource of the high voltage switch, calculating the residual resource of the high voltage switch, characterized in that simultaneously with fixing the current value switching current I _com for each phase during each switching, the current voltage value U _com d is fixed For each phase during each switching, before determining the value of the current worked resource of the high-voltage switch, the current switching current is brought to the rated voltage according to the following expression:
I _t = I _com · U _com / U _nom ,
where I _t is the current reduced value of the switching current, A;
I _com - the current value of the switching current, A;
U _com - the current value of the switching voltage, V;
U _nom - rated voltage of a high-voltage switch, V,
and the value of the current worked resource of the high-voltage switch P _t during this switching is calculated by the following expression:
P _t = (I _t / I _{o nom} ) ² ,
where P _t is the current spent resource of the high-voltage circuit breaker during current switching I _t ;
I _t is the current reduced value of the switching current, A;
I _{o nom} - rated breaking current corresponding to the type of switch, A;
the calculated value of the operating time P _{t is} summed up to the previously accumulated operating time of the high voltage circuit breaker P _s for each phase, the obtained value of the operating life of the high voltage circuit breaker is compared with the switching resistance of the high voltage switch P _k for each phase of this high voltage circuit breaker, and if exceeding the value obtained for the resource unwound p _with the circuit breaker at least for one of the phases of the resource set _to p n high resistance circuit breaker decide to replace the circuit breaker, and if the accumulated value P unwound resource _with less than the high voltage switch resource P _to switching on the circuit breaker resistance, P is determined residual life _of the circuit breaker by the following expression:
P _o = P _to -P _c ,
where P _about - the residual life of the high voltage switch;
P _to - the established resource for switching resistance;
P _with - the worked resource of the high-voltage switch. 2. The method according to claim 1, characterized in that, in addition, for each of the phases when switching the switch, the current current of which exceeds I _nom , the value of the worked resource of the high-voltage switch P _t for each of the phases is reduced by Δ ₁ , determined by the following mathematical expression:

,
where Δ ₁ - correction factor for low switching currents;
I _nom - rated current of the switch corresponding to the type of switch, A;
I _{o nom} - rated breaking current corresponding to the type of switch, A;
I _t is the current reduced value of the switching current, A. 3. The method according to claim 1, characterized in that, in addition, when switching the switch, the current current of which exceeds I _cr , the value of the activated resource P _t for each of the phases, calculated according to the formula 1, is reduced by Δ ₂ , determined by the following mathematical expression:

,
where Δ ₂ - correction factor for critical currents;
I _cr - critical current - tripping current, which is greater than the rated current of the circuit breaker, but less than the rated tripping current, and beyond which the arc time increases significantly, A;
I _{o nom} - rated breaking current, corresponding to the type of switch A;
I _t is the current reduced value of the switching current, A.
I _cr - critical current - tripping current, which is greater than the rated current of the circuit breaker, but less than the rated tripping current, and beyond which the arc time increases significantly, A;
I _{o nom} - rated breaking current corresponding to the type of switch, A;
I _t is the current reduced value of the switching current, A.