WO2012098096A2

WO2012098096A2 - Method for operating a switchgear panel for electrical switchgear

Info

Publication number: WO2012098096A2
Application number: PCT/EP2012/050608
Authority: WO
Inventors: Xiaoting DONG; Uwe Kaltenborn
Original assignee: Schneider Electric Sachsenwerk Gmbh
Priority date: 2011-01-19
Filing date: 2012-01-17
Publication date: 2012-07-26
Also published as: DE102011002870A1; DE102011002870B4; WO2012098096A3

Abstract

A method for operating a switchgear panel (10) for electrical switchgear is described. The switchgear panel (10) has a plurality of electrical components, particularly circuit breakers, isolator/earthing switches or the like. Sensors for measuring operating variables are present, particularly for measuring currents, voltages, temperatures, periods or the like. A simulation model of the thermal response of the switchgear panel (10) is ascertained. The simulation model ascertains at least two further operating variables for each of a number of ambient temperatures. At least one basic equation is prescribed which has at least one time-dependent term and a basic coefficient. The basic coefficient is calculated using a correction method (data fitting) on the basis of the further operating variables ascertained by the simulation model.

Description

Verfahren zum Betreiben eines Schaltfelds einer elektrischen SchaltanlageMethod for operating a control panel of an electrical switchgear

The invention relates to a method for operating a control panel of an electrical switchgear.

In such a panel electrical components of the electrical switchgear are housed, such as circuit breakers or the like. Furthermore, one or more sensors are assigned to such a switching field, which are used for measuring operating variables of the switching field.

It is known to create a simulation model for the thermal behavior of the same for such a switching field. It is possible that the simulation model only relates to the static thermal behavior of the switching field, or that the dynamic thermal behavior of the switching field is also taken into account in the simulation model.

Furthermore, it is known that such a simulation model can optionally be used to monitor the operation of the switching field. For this, however, it is necessary that the calculation of the simulation model takes place as quickly as possible, so that the results of the calculations of the simulation model can be used in real time for the evaluation and influencing of the switching field. This requirement is usually not met for dynamic simulation models, so that the dynamic thermal behavior of the switching field in the operation of the same can usually not be taken into account.

The object of the invention is to provide a method for operating a switching field of an electrical switchgear, in which the dynamic thermal behavior of the switching field can be taken into account during operation.

The invention solves this problem by a method according to claim 1 and by an electrical switchgear according to claim 9.

According to the invention, a simulation model of the thermal behavior of the switching field is determined, and in each case at least two further operating variables are determined by the simulation model for a number of ambient temperatures. On this basis, at least one basic equation is provided which has at least one time-dependent term and a basic coefficient. The basic coefficient is calculated with the aid of a compensation method (English: data fitting) as a function of the further operating variables determined by the simulation model.

With the aid of the now available basic equation, a transfer function can be calculated in real time during the operation of the switching field, with which a forward-looking statement can also be made about the dynamic thermal behavior of the switching field. Based on the transfer function resulting from the basic equation, an optionally required influencing of the switching field can then be carried out. In this way, damage to the panel can be avoided.

In one embodiment of the invention, the operating variables determined for the respective ambient temperatures are checked as to whether they are technically meaningful values. Preferably, a validity range for the simulation model is determined, in which only those determined operating variables are included, which yield technically meaningful values. In this way it is achieved that only technically meaningful values of the determined operating variables are used in the calculation of the basic coefficient.

In a further embodiment of the invention, the two further operating variables may be a component temperature of an electrical component of the switching field and a current. Furthermore, the basic coefficient may be a temperature difference, which represents the temperature increase from an initial temperature of the electrical component to the component temperature.

Other features, applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are illustrated in three figures. All described or illustrated features, alone or in any combination form the subject matter of the invention, regardless of their summary in the claims or their dependency and regardless of their formulation or representation in the description or in the figures.

1 shows a schematic block diagram of an embodiment of an electrical switchgear according to the invention, FIG. 2 shows a schematic flowchart of a method for operating the switchgear of FIG. 1, and FIG. 3 shows an exemplary table for use in the method according to FIG.

An electrical switchgear consists of a plurality of panels. The panels are electrically connected to each other via busbars. In the individual panels different electrical components are housed, such as circuit breakers, isolator / earthing switch, fuses, power electronic components and the like. Among other things, branches from the busbars to electrical consumers are realized via these electrical components.

In the figure 1, a single panel 10 of a switchgear is shown. The panel 10 has a cabinet-shaped housing which is placed on a horizontal floor. The panel 10 is divided into several housing parts, wherein individual housing parts may be formed as a gas-tight container. The electrical components of the panel 10 are housed in the individual housing parts and containers.

A first temperature sensor 12 is assigned to an electrical component of the switching field 10. The first temperature sensor 12 measures a component temperature TB, ie the temperature that has the associated electrical component of the switching field 10 due to their operation.

The first temperature sensor 12 can be arranged on a grounded component of the switching field 10, for example on a disconnector / earthing switch. In this case, the first temperature sensor 12 may be formed, for example, as a thermocouple. However, the first temperature sensor 12 may also be attached to a current-carrying component, for example to an electrical conductor. In this case, the first temperature sensor 12 may be formed, for example, as an optical sensor element. If the switching field 10 has a gas-tight container in which, for example, a circuit breaker is accommodated, then the first temperature sensor 12 can be mounted, for example, on the surface of the gas container.

It is understood that the first temperature sensor 12 can also be arranged on other suitable components of the switching field 10. It is also understood that a plurality of such first temperature sensors 12 may be present, with which a plurality of component temperatures TB can be measured.

Furthermore, a second temperature sensor 14 is provided, which is arranged independently of the electrical components of the switching field 10. The second temperature sensor 14 measures an ambient temperature TU, ie the temperature that is present in the vicinity of the electrical components of the switching field 10.

The second temperature sensor 14 may be located anywhere in the room or in the building in which the cubicle 10 is installed. However, the second temperature sensor 14 may also - be arranged within the switching field 10 - in deviation from the figure, in this case, independent of an electrical component, so for example on an outer wall of the housing of the panel 10. It is understood that a plurality of second Temperature sensors 14 may be present.

In a manner not shown, the switch panel 10 more sensors for measuring one or more operating variables of the same are assigned. The operating variables to be measured may be, for example, currents and / or voltages or the like. Alternatively, it is also possible that one of the mentioned operating variables is not actually measured, but is otherwise determined, for example with the aid of modeling, from other operating variables.

The component temperature TB and the ambient temperature TU are fed to a control unit 16. Likewise, the measured or otherwise determined operating variables are supplied to the control unit 16. The control device 16 may be, for example, an electronic computing device that is programmed according to the following explanations. The control unit 16 can be arranged completely independently of and outside of the switching field 10 within the switching field 10 or, as shown in the figure.

FIG. 2 shows a method for operating the electrical switchgear, in particular a method for operating the switchgear panel 10 of FIG. 1.

In a first step 21, a simulation of the temporal thermal behavior of the switching field 10 is performed. For this purpose, for example, the following methods can be used individually or in combination: a heating network model (eg TNM = thermal network method) and / or a two- or three-dimensional fluid mechanics model (eg CFD = computational fluid dynamics) and / or a model the finite element method (FEM) and / or a boundary element method (BEM). The simulation can be subdivided into sub-steps, for example in such a way that a static consideration of the thermal behavior of the switching field 10 is made first and only then is the temporal or dynamic thermal behavior taken into account. The simulation is performed by a computing device, such as a personal computer. If appropriate, the simulation can be carried out with the aid of the control unit 16. As a result of the first step 21, there is then a simulation model of the thermal behavior of the switching field 10 as a function of time on the computing device.

In a second step 22, a validation of the simulation model present on the computing device is carried out. For this purpose, measurements of operating variables of the switching field 10 are carried out during its operation. The operating variables of the switching field 10 may be currents, voltages, temperatures, durations or the like. The determined actual measured values of the operating variables are compared with correspondingly associated values determined by the simulation model. Based on the deviations of the values determined by the simulation model from the actual measured values of the same operating variables, the simulation model can be corrected. This validation can in turn be performed by a computing device or possibly also by the controller 16. To determine measured values, for example, the first and

second temperature sensors

12, 14 can be used. As a result of the second step 22, an optimized simulation model of the thermal behavior of the switching field 10 as a function of time then exists.

It should be noted that the second step 22, that is to say the validation of the simulation model for the thermal behavior of the switching field 10, may also be omitted.

In a third step 23, one or more transfer functions are determined from the optimized simulation model of the thermal behavior of the cubicle 10.

For this purpose, a validity range for the optimized simulation model is determined in a first substep.

The starting point are those actually measured operating variables of the switching field 10, which have been determined during the operation of the switching field 10 for the purpose of validating the simulation model. These measured operating variables are assigned to the ambient temperature TU, which has also been measured in the aforementioned measurement of the operating variables.

Now, the same operating variables are determined with the aid of the simulation model for a first changed ambient temperature TU1. Thereafter, again the same operating variables of the switching field 10 are determined with the aid of the simulation model for a second changed ambient temperature TU2, and so on. For example, the said operating variables of the simulation model can be determined for ambient temperatures, have mutually equidistant intervals, for example, the ambient temperatures TUi = -20 ⁰ C, -10 ⁰ C 0 ⁰ C, 10 ⁰ C, 20 ⁰ C, 30 ⁰ C , 40 ^° C, 50 ^° C.

Thereafter, the operating variables determined for the respective ambient temperatures are checked as to whether these are technically meaningful values.

This test can be carried out automatically by setting limit values for the individual operating variables and then by checking whether these limit values have been complied with or exceeded. This check can be performed by a computing device or possibly also by the controller 16. However, the test can also be carried out by an operator of the electrical switchgear 10 in such a way that the operating variables ascertained by the simulation model are tested in each case with regard to their technical plausibility. It is understood that other tests and combinations thereof can be carried out.

If any operating variables exceed the given limit values or if any operating variables are not plausible, the respectively associated ambient temperature is deleted from the scope of the simulation model. This leaves only those ambient temperatures and the operating variables determined for these ambient temperatures within the scope of the simulation model, which yield technically meaningful values.

Those ambient temperatures and associated operating variables of the switching field 10, which are within the validity range of the simulation model, are now suitably put together.

This will be explained below by way of example. It is assumed that the scope of the simulation model ambient -20 ⁰ C, -10 ⁰ C, 0 ⁰ C, 10 ⁰ C, 20 ⁰ C, 30 ⁰ C, 40 ⁰ C, 50 ⁰ C comprises, and that for Each of these ambient temperatures has been predetermined by the simulation model in each case a plurality of streams, 500A, 1000A, 1500A, 2000A, 2500A, 3000A. For these operating variables of the switching field 10, in each case one component temperature TB has been determined by the simulation model.

Thereafter, from this component temperature TB in each case a temperature difference Td has been determined, which represents only the temperature increase from an initial temperature Ta of the component, ie the component temperature TB before the application of the respective current, to the finally determined component temperature TB.

FIG. 3 shows a table which represents the example explained above. In the vertical, the ambient temperatures mentioned are plotted and in the horizontal these currents are applied. In the individual fields of the table, a value for the determined temperature difference Td is then entered for each pair of operating variables ambient temperature and current. The value inscribed in the individual fields thus indicates by how many degrees the temperature of the component underlying the simulation model changes, if the associated ambient temperature is present and the associated current flows.

It should be noted that the above-described compilation according to FIG. 3 is only an example, and that therefore other possibilities of compiling the operating variables of the switching field 10 determined by the simulation model and within the scope of validity are also conceivable. For example, it is also possible to represent the operating variables in the form of a three-axis characteristic diagram.

In a second sub-step, one or more basic equations for the transfer function (s) are now specified. The basic equations contain one or more parameters and then the parameters of these basic equations are determined.

As an example, a single basic equation is given as follows:

T (t) = Ta + Td * (1-k * e ^{-t / τ} )

With

t = time,

T (t) = time-dependent temperature,

Ta = starting temperature,

Td = temperature difference,

k = weighting coefficient

τ = time coefficient.

For this basic equation, the temperature difference Td can be determined, for example, as follows:

Td = a + b · TU + c · TU ²

with a, b, c = parameter.

It is understood that even higher order equations or other equations may be used to determine the temperature difference Td.

The parameters a, b, c can be determined, for example, with the help of the table of FIG. It is understood that other types of compilations can be used in a corresponding manner for the determination of the parameters a, b, c. For the purpose of determining the parameters a, b, c, methods of the so-called data fitting can then be used, for example methods for regression calculation, e.g. the method of least squares.

To determine the weighting coefficient k and the time coefficient τ, the first sub-step is used. As has been explained, in this first sub-step a validity range for the optimized simulation model is determined. As part of this determination, the measured operating variables of the switching field 10 are calculated for a number of different ambient temperatures TUi.

From these calculated operating variables now a certain ambient temperature is picked out and for this ambient temperature, the respective time profile of the differential temperature for different currents is considered. From the differences of the temporal progressions is then closed on the weighting coefficient k and the time coefficient τ.

The determined values for the temperature difference Td, the weighting coefficient k and the time coefficient τ are then inserted into the basic equation. In the present first example, an equation for calculating the time-dependent temperature T (t) is thus available.

In general, the basic equation has a time-dependent term and a basic coefficient. In the above example, the time-dependent term is realized by the e-function and the temperature difference Td represents the basic coefficient. The basic coefficient is then calculated as explained by way of example with the aid of a compensation method as a function of the further operating variables determined by the simulation model.

In a third sub-step, this equation for the time-dependent temperature T (t) is converted into the associated transfer function (s).

Such a transfer function is generally a mathematical relationship that relates at least two or more operating variables of the switching field 10 to one another. Such a transfer function thus characterizes the thermal behavior of the switching field 10 by the selected operating variables.

In particular, a transfer function is a mathematical equation that links together at least two or more operating variables of the switching field 10. The combination of the operating variables is carried out in particular via mathematical functions and parameters, the latter may be constant or dependent on operating variables of the switching field 10.

One value is specified for one of the operating variables of the transfer function, and a value is determined for the other operating variable (s), which is directed into the future. For example, the one, predetermined value can be determined by means of a measurement and for the other / n operating size / n can be determined using the transfer function, a maximum allowable value, which may not be exceeded.

The transfer function is constructed in such a way that, for a specific state of the switching field 10, the result of the transfer function is as similar as possible to a result of a corresponding combination of the corresponding operating variables in the optimized simulation model. This means that the parameters of the transfer function are selected such that the result of the transfer function for the specific state of the switching field 10 is a result that corresponds to a result of a corresponding combination of the corresponding operating variables in the optimized simulation model.

In the case of an example directed to the switching field 10 of FIG. 1, a specific value I can be _{specified for} a current I flowing within the switching field 10, and it can then be determined by means of a first transfer function how long, ie for which maximum time duration t _max this particular value I _{geg of} the current I may be present or allowed to flow without causing damage to the panel 10. When determining the maximum time duration t _max , the thermal behavior of the switching field 10 is taken into account by the transfer function. In particular, it is considered that damage occurs at the switching field 10 when the component temperature TB exceeds a limit temperature Tgrenz.

On the basis of the equation for the time-dependent temperature T (t) explained above, in the aforementioned first example, based on the determined value I _{geg of} the current I, the following _results :

T (tmax) = Ta + Td * (1-k * e ^{-tmax / τ} ) = Tlimit

This Zusammenheng can be solved, for example, in terms of t _max , that the value for t _{max is} always increased. The value for t _max , with which the equation reaches the limit temperature T limit as accurately as possible, then represents the sought maximum time duration t _max .

In an example which is likewise directed to the switching field 10 of the figure, a specific value t can be _{given for} a time duration for the flow of a current I within the switching field 10, and it can then be determined with the aid of a second transfer function, which maximum value I _{max of} this Strom I may be present in future or may flow without causing damage to the panel 10. When determining the maximum current I _max , the thermal behavior of the switching field 10 is taken into account by the transfer function.

On the basis of the above-explained equation for the time-dependent temperature T (t), the above-mentioned second example provides the following:

T (tgeg) = Ta + Td * (1-k * e ^{-tgeg / τ} )

The equation is based on a first value for the current I, for example, the nominal value for the current I.

By way of example, this equation can be "solved" with regard to the maximum permissible current I _max so that the respective underlying value for the current I is always further increased. The value for the current I, with which the equation is fulfilled as accurately as possible, then represents the sought maximum current I _max .

It is understood that other transfer functions with different basic equations and parameters can be formed in a corresponding manner. The determination of the transfer function (s), in particular the determination of the respective parameters, can be carried out with the aid of a computing device, if necessary with the aid of the control device 16.

The second and third sub-steps have been explained above by way of example, namely, the single basic equation T (t) = Ta + Td * (1-k * e ^{-t / τ} ). It is now possible that two or more basic equations exist. For example, the following two basic equations may exist:

T1 (t) = T1a + T1d * (1-k11 * e ^{-t / τ1} -k12 * e ^{-t / τ2} )

T2 (t) = T2a + T2d * (1-k21 * e ^{-t / τ2} -k22 * e ^{-t / τ2} )

With

t = time,

T1 (t), T2 (t) = time-dependent temperatures,

T1a, T2a = outlet temperatures,

T1d, T2d = temperature differences,

k11, k12, k21, k22 = weighting coefficients,

τ1, τ2 = time coefficients.

The determination of the coefficients is carried out with the aid of corresponding tables, as they are given by way of example in FIG. From the resulting equations corresponding transfer functions can be derived.

As a result of the third step 23, there is thus at least one transfer function which relates to and represents a specific aspect of the thermal behavior of the switching field 10.

A fourth step 24 illustrates the operation of the panel 10. During operation of the panel 10, the transfer function (s) is / are calculated once or more than once, always for the current state of the panel 10. Based on the results / s of the transfer function / s then the further operation of the panel 10 can be influenced in general. The latter influencing of the switching field 10 is shown in FIG. 2 by an arrow 26.

If, for example, the first transfer function is calculated during operation for the current state of the switching field 10, then the result of the first transfer function represents a value, as explained _above , for how long, ie for which maximum time duration t _max , is the predetermined current I _in within of the switching field 10 may be present or allowed to flow without causing damage to the panel 10. After the first transfer function has been calculated, it is thus possible to monitor whether the said maximum time duration t _{max is} exceeded during further operation of the switching field 10 or not. If the maximum time duration t _{max is} exceeded, then, for example, the current I flowing within the switching field 10 can be switched off. Damage to the panel 10 can thus be avoided in a forward-looking manner with the aid of the transfer function.

For example, when the second transfer function calculated during the operation for the current state of the switching field 10, thus provides - as explained - the result of the second transfer function to the maximum value I _max of the inside of the switch box 10 flowing current I represents the t during the time period _geg may be present or flow, without causing damage to the panel 10. After the second transfer function has been calculated, it is thus possible to monitor whether the said maximum current I _{max is} exceeded during further operation of the switching field 10 or not. If the maximum current I _{max is} exceeded during the time period t _geg , then, for example, the current I flowing within the switching field 10 can be switched off. Damage to the panel 10 can thus be avoided in a forward-looking manner with the aid of the transfer function.

The calculation of the transfer function (s) is performed by a computing device. Optionally, this calculation can be performed by the controller 16. The calculation of the individual transfer functions can be carried out, for example, at equidistant time intervals.

The calculation of a single transfer function requires only a very small amount of time for the computing device. The calculation of a single transfer function can therefore be performed in real time. This means that the result of the transfer function is calculated by the computing device so quickly that an optionally required influencing of the switching field 10 due to the determined result of the transfer function can be carried out in such a timely manner that any damage to the switching field 10 is avoided in any case. In other words, this means that the transfer function is calculated so quickly that a reaction resulting from the result of the transfer function still achieves its desired effect in each case.

If, for example, the simulation model of the thermal behavior of the cubicle 10 were used instead of the transfer function during the operation of the cubicle 10, the creation of this simulation model would require considerably more time and therefore could not be performed in real time. This would mean that damage to the panel 10 would already occur before this damage could be detected by the simulation model.

The determination of the simulation model for the thermal behavior of the switching field 10 is therefore carried out in particular before the actual operation of the switching field 10. If applicable, the same applies to the validation of the simulation model. Likewise, the determination of the basic function (s), in particular of the respective parameters, is carried out before the actual operation of the switching field 10. During operation, only the transfer function (s) for the respective current state of the switching field 10 is / are determined in real time, and possible influences of the switching field 10 are / are based only on this transfer function (s).

With the help of the transfer function (s), it is therefore possible to monitor the operation of the switching field 10. As has been explained, each individual transfer function covers a certain aspect of the thermal behavior of the cubicle 10, so that each of these aspects can be monitored by the associated transfer function. If, in one or more of the transfer functions, it is determined that damage is to be expected from the switch panel 10, then the switch panel 10 can be influenced before the damage occurs so that the damage does not even occur.

The method described above for operating an electrical switchgear can also be used very generally for the purpose of describing the state of the electrical switchgear.

Furthermore, it should be noted that the described method can be used in a corresponding manner in other electrical devices, for example in transformers or the like.

Claims

Method for operating a switching field (10) of an electrical switchgear, wherein the switching field (10) has a plurality of electrical components, in particular circuit breaker, isolator / earthing switch or the like, and wherein sensors for measuring operating variables are present, in particular for the measurement of currents , Voltages, temperatures, time periods or the like, characterized in that a simulation model of the thermal behavior of the switching field (10) is determined (21) that from the simulation model for a number of ambient temperatures (TUi) at least two further operating variables are determined that at least one basic equation is specified, that the basic equation has at least one time-dependent term and a basic coefficient, and that the basic coefficient is calculated using a data fitting as a function of the further operating variables determined by the simulation model t will.
Method according to Claim 1, wherein the basic equation has at least one weighting coefficient (k) and / or at least one time coefficient (τ), and wherein the weighting coefficient (k) and / or the time coefficient (τ) depend on the further operating variables determined by the simulation model be calculated.
Method according to one of claims 1 or 2, wherein from the basic equation, a transfer function is derived, which sets the two other operating variables of the switching field (10) with each other.
Method according to one of the preceding claims, wherein the operating variables determined for the respective ambient temperatures (TUi) are checked as to whether they are technically meaningful values.
The method of claim 4, wherein a validity range is determined for the simulation model in which only those determined operating variables are included, which yield technically meaningful values.
Method according to one of the preceding claims, wherein the two further operating variables are a component temperature (TB) of an electrical component of the switching field (10) and a current (I).
The method of claim 6, wherein the component temperature (TB) is measured on an electrical component of the switching field (10).
Method according to one of claims 6 or 7, wherein the basic coefficient is a temperature difference (Td) representing the temperature increase from an initial temperature (Ta) of the electrical component to the component temperature (TB).
Electrical switchgear with a switching field (10), wherein the switching field (10) has a plurality of electrical components, in particular circuit breaker, isolator / earthing switch or the like, and wherein sensors for measuring operating variables are present, in particular for measuring currents, voltages, Temperatures, times or the like, characterized in that a control device (16) for carrying out the method according to any one of the preceding claims is present.