Patent Application
20110176933
The present invention relates to a method for determining the functional relation of several pumps in an installation, which may be controlled in their rotational speed.
Particularly in heating installations of larger buildings or of a more complex construction type, a multitude of pumps, i.e. centrifugal pumps, with an electric motor driving these, are installed, in order to reliably supply the individual installation parts with fluid or heat. Modern pumps of this type are typically controlled by frequency converter, so that with regard to power, they may supply over a wide range and may be operated in a different manner depending on requirement. If a multitude of such pumps cooperate in an installation, be it by way of parallel connection, series connection or a combination of this, then a complex hydraulic network results, which from the start must be known with regard to its structure, i.e. with regard to its functional relationship, in order to be able to energetically optimize the operation of the entirety of the pumps. Particularly with older installations it may be the case that the hydraulic connection plan is no longer available. Even this may no longer be unambiguously determined with a sufficient accuracy by way of the existing pipework. It is then necessary to determine the functional relationship of the pumps.
Against this background, it is an object of the present invention to provide a method for determining the functional relationship of several pumps in an installation, which may be controlled in their rotational speed, with which this functional relationship, thus quasi the hydraulic circuit of the installation, may be determined in an unambiguous manner.
According to the present invention, the above object is achieved by the features specified in the independent claim(s). Advantageous designs of the present invention are specified in the dependent claims, the subsequent description and the drawing.
According to the present invention, the functional relationship of several pumps in an installation which are controllable in their rotational speed, is determined by way of changing the rotational speed with regard to at least one pump, and determining at least one functional relationship of the installation from the hydraulic reaction resulting therefrom. Depending on the scope of the functional relationship to be determined, one may activate one or also more pumps with a changed rotational speed, in order to determine this relationship. Thus, for example, for ascertaining whether two pumps are connected in parallel or in series, it is sufficient to activate one of the pumps with an increased rotational speed, in order then, by way of the pressure measurement or throughput measurement compared to the initial condition, to determine in which way these pumps are connected.
According to one advantageous further formation of the present invention, the method is applied in three basic method steps:
a) In a first method step, all pumps built into the installation are preferably activated with a constant rotational speed, and a hydraulic variable is detected for each pump or for each consumer assigned to the pumps or for each consumer group if several consumers are assigned to a pump. Typically, the pumps thereby are activated with a constant average rotation speed, and specifically until quasi stationary values set in. These values are detected either with regard to the pump or to the consumer, and thereby it is optionally the case of the pressure or the volume flow, wherein these do not necessarily need to be detected in a direct manner, but may also be indirectly determined in a manner known per se by way of other variables, e.g. electrical variables of the drive of the pumps manner;
b) Then one after the other, in each case one of the pumps or several pumps are activated with a changed rotational speed, and the change of the hydraulic variable which results in each case is detected. Thus, each individual pump is typically activated with a rotational speed, which is increased compared to step a), and then the changes of the hydraulic variables, which result either on the consumer side or the pump side, are detected, wherein on the part of the pump, the hydraulic variables of the pump activated with the changed rotational speed as well as those of the other pumps are detected. Basically thereby, it is of no significance as to whether the changed rotational speed is one which is increased or decreased compared to the rotational speed according to step a, but as a rule a rotation speed which is greater in comparison is advantageously selected. It is to be understood that in the same manner, one after the other, all pumps must be operated either with a rotational speed which is increased or reduced compared to the rotation speed in step a, in order to detect the hydraulic changes of the hydraulic variables which thereby result.
c) In a third method step, then after the changes of the hydraulic variables are detected, the assignment of the pumps or pump group to the consumers or consumer groups is determined by way of these detected hydraulic variable changes.
The method according to a preferred embodiment of the present invention, with the advantageous application of pumps controlled by a frequency converter, may be implemented into the digital frequency converter electronics, wherein then a data connection of the pumps amongst one another should be formed, be it wireless per radio or for example via a network cable, in order to suitably coordinate the pumps with regard to the method and furthermore to determine the hydraulic variables at the pumps or at the consumers. However, this method may also be implemented in a separate control, which is data-connected to the pumps and, as the case may be, to the consumers or their sensors in a wireless or wired manner.
The method according to a preferred embodiment of the present invention offers the huge advantage that it may be carried out with equipment which is present in the heating installation in any case, i.e. with the exception of the control and the data connection, one does not need to provide any additional measures with regard to the installation. The control and data connection may however be integrated into the pumps with only low additional costs, given a suitable design of these pumps.
The evaluation of the thus determined hydraulic variables and variable changes may be effected in a simple manner. Thereby, the methods differ essentially as to whether the hydraulic variables or their changes are detected on the part of the pump or on the part of the consumer.
If the variables are detected on the part of the consumer (on the consumer side), i.e. at a consumer or a consumer group if several consumers are assigned to a pump, then according to a further formation of the method of the present invention, at the pumps which on activation with a changed rotational speed produce the same consumer-side hydraulic variable changes, one ascertains that these are assigned to a pump group. A pump group consists of two or more pumps which are connected directly in parallel and/or series. With the consumer side variable detection, the first assignment step thus lies in determining whether the pumps are hydraulically connected as individual pumps or in groups, in the installation.
According to a further advantageous design of the method of the present invention, when, with a change in rotational speed of one or consecutively also of several pumps, only one consumer or a consumer group is influenced in an increasing or reducing manner according to the change in rotational speed, one ascertains that then the pump or the pumps are directly assigned to the respectively influenced consumer or to the respectively influenced consumer group, i.e. no further pumps are located in the conduit path between the previously mentioned pump/previously mentioned pumps, and the consumer or the consumer group.
In order to determine the functional relationship within a pump group, according to a further formation of the method according to the present invention, one envisages activating all pumps of the pump group with a constant rotational speed, thus for example according to method step a), wherein then the pressure difference produced by the respective pumps is detected at the respective pump by a differential pressure sensor. Then, one after the other, in each case one of the pumps is activated with a changed, preferably increased pressure and the differential pressure change or rotational speed changes of the other pumps which result thereby is detected, whereupon then the assignment of the pumps within the pump group is determined by way of the detected variable changes, as results by way of the hydraulic laws with the parallel connection and series connection of the pumps. In order to be able to ascertain the functional relationship within the pump group, either the pumps of a pump group are activated subsequently with a changed, preferably increased rotational speed and the throughput quantity through the respective pump is detected, or however the pumps are activated one after the other in each case for producing an increased differential pressure, wherein then the pressure levels, which sets in, of these and of the other pumps, is detected, and the assignment of the pumps within the pump group is ascertained by way of the changes which result as the case may be.
According to one advantageous further formation of the method according to the present invention, the pump or the pumps, which with their rotational speed change influence two or more consumers or consumer groups in a increasing or reducing manner according to the rotational speed change, is or are assigned according to the number of influenced consumers or consumer groups. Thus one may determine which pumps affect which consumers and thus the assignment of the pumps amongst one another may be determined.
It is particularly advantageous if, with the method according to the present invention, it is not the absolute values of the hydraulic variables or variable changes which are detected, but merely the direction, since then on the one hand one may apply a very simple sensor means which is not calibrated, and on the other hand the evaluation only requires a low computational effort as well as reduced memory requirement. Thus for carrying out the method according to the present invention, it is sufficient to detect whether the respectively detected hydraulic variable increases, reduces or remains the same, given a change in the rotational speed or pressure of a determined pump. Thus, it is merely a question of a simplified direction detection, which is adequately accurate when it may be categorized into three groups, specifically larger (+1), smaller (−1) and equal (0).
If the method according to the present invention is to be carried out by way of detecting the hydraulic variables of the pumps, thus for example the pressure or the volume flow, which as a rule, is more favorable with regard to the installation, since heating circulation pumps controlled by a frequency converter are nowadays usually equipped with differential pressure sensors, then it is useful firstly once to determine with the method as to whether the hydraulic installation is a hydraulic network or whether it consists of two or more installation parts which are independent of one another. With installation parts which are independent of one another, a rotational-speed-changed or pressure-increased activation of the pump has no influence on the other part, so that in this manner, with the method, one may firstly be able to determine the installation parts which are hydraulically connected to one another.
The method with hydraulic variables of the pump, typically pressure or differential pressure or volume flow are detected for determining the functional relationship, in turn differ fundamentally from one another.
If, as is envisaged according to a further formation of the present invention, the volume flows and thus volume flow changes as hydraulic changes are detected at all pumps, then the functional relationship of the pumps may be determined as follows, wherein hereinafter the changes on activating a pump with an increasing rotational speed are noted. However, one must emphasize that the changes may also be used in an analogous manner if the activation is effected with a reduced rotational speed:
A matrix is formed, in which the hydraulic changes of at least one hydraulically independent installation part are detected, wherein advantageously here too, the direction changes are detected, thus the matrix is formed with the values 0 for remaining the same, +1 for increasing and −1 for reducing. Thereby, for each pump, the changes of the hydraulic variables at this pump as well as at the other pumps, which result with its activation with a changed rotational speed, are specified in rows. Moreover, a column is assigned to each pump, whereby the rows within the matrix are sorted, and specifically increasing from the top to the bottom according to their number of increasing changes (+1), and the columns increasing from the left to the right according to their number of increasing changes (+1). Thus the changes of the pump which produces the fewest increasing changes in the entirety of the pumps are detected in the uppermost row of the matrix, and the associated column of this pump connects at the same location at the top left of the matrix. The pump with the most increasing changes is in the last, thus lowermost row, wherein then also the last column, thus the column at the far right, is assigned to this pump. It is to be understood that the matrix may also be arranged exactly in the reverse manner, since it is compellingly mirror-symmetrical with regard to its diagonals.
The matrix is divided by a diagonal, which runs from the one to the other matrix axis, which quasi intersects or erases the fields of the matrix in which an increasing variable change, thus typically a 1 is located. These are the fields with which the pump assignment of the column and row corresponds. By way of observing the number of increasing changes of the hydraulic variables in each column below the previously mentioned diagonal or in each row above the previously mentioned diagonal, one may determine which pumps are connected hydraulically in parallel and which ones hydraulically in series.
With the pumps with which an equal number of increasing changes (+1) of the hydraulic variables in the columns below the diagonal or in the rows above the diagonal of the matrix is given, it is the case of pumps connected in parallel, thus of those pumps which deliver from the same conduit and from the same pressure level.
According to a further formation of the method according to the present invention, pumps which are assigned directly to a consumer or to a consumer group are determined, i.e. which deliver into such a consumer or a consumer group without intermediate connection of further pumps. Hereby, it is the case of pumps with which no increasing change of the hydraulic variables in a row below the diagonal or in a column above the diagonal of the matrix is present. The first pump of the matrix may belong to this as the case may be, which is assigned to the first row and the first column and lies on the diagonal. This results from the row sorting or the column sorting.
According to a further formation of the method according to the present invention, by way of evaluating the matrix, one determines how many pumps are hydraulically connected in series upstream of the respectively considered pump. For this, the number of increasing changes of the hydraulic variables in the columns below the diagonals or in the rows above the diagonals of the matrix, are detected. This number corresponds to the number of the pumps which are connected in series upstream of the respective pump, wherein no information is given with regard to the hydraulic connection of the pumps connected in series upstream.
According to one method variant of the present invention, with which the matrix is formed in the same manner as previously described, one may determine which pumps are connected hydraulically in parallel and which ones hydraulically in series, by way of the number of increasing changes of the hydraulic variables in each row below or in each column above a diagonal dividing the matrix and running from one to the other matrix axis. Thereby, according to a further formation of the method according to the present invention, the number of increasing changes of the hydraulic variables in the rows below the diagonal or in the columns above the diagonal of the matrix may be used for determining the number of pumps which are hydraulically connected in series downstream of the respective pump, and thus the number may be assigned.
The method according to the present invention, if the hydraulic variables of the pump are evaluated, may either be carried out by way of detecting the volume flow of the pumps or however alternatively the pressure or differential pressure of the pumps. If the determining is to be effected via the pressure changes, then according to the present invention, a matrix is formed in the same manner as previously described, in which the hydraulic changes of at least one hydraulically independent installation part are detected, wherein here too in rows for each pump, the changes of the hydraulic variable which results with its activation for delivering with a changed pressure, is specified at this pump and the other pumps, and wherein a column is assigned to each pump. Thereby, the rows are sorted increasing from the top to bottom according to their number of reducing changes (−1) and the columns are sorted from the left to the right according to their number of reducing changes, wherein then one determines which pumps are hydraulically connected in parallel and which are connected hydraulically in series by way of the number of reducing changes of the hydraulic variable in each column below, or in each row above a diagonal which divides the matrix and which runs from the one to the other matrix axis. Here too, the diagonal forms a symmetrical partition of the matrix and runs through the fields which have been indicated as always increasing and which in the row and column concern the same pump in each case. These fields are not co-counted with the subsequent evaluation, just as with the previously described one.
Thereby, an equal number of reducing changes of the hydraulic variables in the columns below the diagonal or in the row above the diagonal of the matrix indicates a connection of the respective pumps in parallel.
A different number of decreasing changes of the hydraulic variables in columns below the diagonal or in rows above the diagonal indicates the connection of the respective pumps in series.
If a row below the diagonal or a column above the diagonal of the matrix has no reducing change of the hydraulic variables, then this determines the direct assignment of the respective pump to a consumer or to a consumer group.
The number of reducing changes of the hydraulic variables in the columns below the diagonal or in the rows above the diagonal of the matrix according to a further formation of the method according to the invention indicates the number of pumps which are hydraulically connected upstream in series of the respective pump.
According to a further formation of the method according to the present invention, one alternatively determines which pumps are connected hydraulically in parallel and which ones are connected hydraulically in series, by way of the number of reducing changes of the hydraulic variables in each column below, or in each row above a diagonal dividing the matrix and running from one to the other matrix axis. Thereby, the pumps which have the same number of reducing changes of the hydraulic variable in the column below, or in the row above the diagonal of the matrix, are connected hydraulically in parallel, and those with a different number are connected hydraulically in series.
According to a further formation of the method according to the present invention, the number of the reducing changes of the hydraulic variables in the rows below the diagonal or in the columns above the diagonal of the matrix indicates the number of the pumps which are hydraulically connected in series downstream of the respective pump.
Thus it becomes clear that the previously described matrix unambiguously determines the functional relationship of the pumps when the hydraulic variable change is detected at each pump. On detecting hydraulic changes at the consumer or consumer group, as the case may be, it may be necessary as initially described, to differentiate additional pump groups as to whether they are connected in parallel or series by way of changing a hydraulic variable of the pump.
The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
a is a hydraulic circuit diagram of an installation with several pumps and consumers according to a preferred embodiment of the present invention;
b is a matrix with regard to the installation according to
a is a circuit diagram of four pumps arranged in parallel in accordance with a preferred embodiment of the present invention;
b shows the temporal behavior of the pumps with a pressure increase;
a is a circuit diagram of a pump group of pumps arranged in parallel and in series;
b shows the behavior of the pumps with an activation with a changed rotational speed;
a is a circuit diagram of three pumps arranged in parallel;
b shows the behavior of the pumps with a change in rotational speed;
a is a circuit diagram of three pumps arranged in series;
b shows the behavior of the pumps with activation with a change in rotational speed;
The hydraulic installation represented by way of
The installation preferably consists of two installation parts which are hydraulically independent of one another, specifically of the installation part represented at the bottom right in
For carrying out the method, now firstly, all pumps PU1 to PU11 are preferably activated with a constant rotational speed, typically of a medium rotational speed which is selected such that the installation is operated according to directed use, but reserves are present so that the pumps, as the case may be, may be activated with a rotational speed which is increased with respect to this. With regard to the pumps, it is typically the case of heating circulation pumps, which are controlled by frequency converter, as are normal in the market.
All pumps are operated at a constant rotational speed and this rotational speed should be constant with respect to the respective pump, but of course the rotational speeds may differ amongst one another. If one of the pumps during the method must be activated with a changed rotation speed on account of a requirement on the part of the installation, then this may be effected when the correspondingly changed rotational speed is taken numerically into account. Pressures are detected at the sensors S1, S3, S6, S7, S10, S11 during this activation with constant rotational speed. Now a first pump, e.g. the pump PU1 is activated with a changed rotational speed, for example with an increased rotational speed and the changes which set in as the case may be or also the non-changes, are detected by way of the sensors S1, S3, S6, S7, S10, S11.
A matrix is usefully set up for this, as is represented in
On activating the pump PU1 with an increased rotational speed, thus according to
The matrix representation here is set up only for a simplified numbered representation, but is basically not necessary for evaluation. By means of the activation it may now be ascertained for starters that the pumps PU1-PU10 have no influence on the sensor S11 whatsoever and thus on the consumer V6. Vice versa the pump PU11 has no influence at all on the consumers V1-V5 from which it results that it hereby must be the case of two installation parts which are independent of one another, wherein pump PU11 evidently only supplies the consumer V6.
With the remaining installation part, which comprises the pumps PU1-PU10, firstly one examines which pumps are arranged in pump groups, i.e. which pumps are connected into a group in parallel or series. The pumps which on the consumer side cause the same hydraulic changes with a change of their rotational speed, are connected into groups. This, as is to be deduced from the matrix according to
One then determines which pumps, with a change of rotational speed, influence only one consumer or only one consumer group according to the rotation speed change, i.e. with an increase in rotational speed influence in a pressure increasing manner and with a rotational speed reduction in a pressure-reducing manner. Since, with the embodiment example which is represented by way of
However, one may not only ascertain by way of these assignments as to which pumps are directly assigned to a consumer, but moreover which consumers are supplied by which pumps at all. Thus, it is evident that the pump PU10 only affects the consumer V5 and this in a direct manner. With regard to the pump group PU8 and PU9, one may recognize that these influence the sensors S1, S3, S6, S7 in the same direction, i.e. that with an activation of the pump with an increased rotational speed, a higher pressure drops at these sensors, i.e. an increasing pressure change is given. This says that the pumps PU8 and PU 9 feed the consumers V1-V4 but only indirectly, i.e. that yet other pumps need to be intermediately connected. With regard to the pumps PU4 and PU5, one may ascertain in the same manner that they supply the consumers S1 and S3, but however likewise only in an indirect manner, since the consumers V3 and V4 are directly supplied by the pumps PU6 and PU7 respectively, and since the pumps PU4 and PU5 as a pump group however do not influence these consumers in the same direction, it results that the pump group PU4 and PU5 as well as the pump PU6 and the pump PU7 are connected in parallel, wherein the pumps PU6 and PU7 in each case are assigned to the associated consumers V3 and V4, whereas the pump group PU4 and PU5 affect the consumers V1 and V2, but likewise not in a direct manner.
Inasmuch as this is concerned, one merely yet needs to determine how the pump groups are connected. These three groups of pumps PU8 and PU9, PU4 and PU5 as well as PU1 and PU2 therefore need to be examined further as far as this is concerned. However further sensors are required for this, which detect the differential pressure of the respective pumps of the pump group or the throughput. With the embodiments according to
If the arrangement of the pumps is to be determined by way of pressure sensors thus differential pressure sensors parallel to the pump, then one of the pumps of a pump group after all have been activated for producing a constant pressure, activates one of the pumps for producing this increased pressure. This is effected with the examples according to
As the above explanations illustrate, thus the circuit diagram according to
Inasmuch as this is concerned, it is often more favorable to design the method according to the present invention exclusively with pump-side pressure sensors, differential pressure sensors and throughput sensors, as this is represented by way of the
For the evaluation of the matrix according to
The functional relationship, i.e. the construction of the installation may be directly evaluated by way of this matrix. Thus, firstly in the same manner as with the first embodiment example, by way of the zeros in the first column below the diagonal or in the first row above the diagonal, one may ascertain that the pumps PU1-PU10 belong to a different installation part than the pump PU11, since this pump only influences its own sensor q11.
By way of the number of increasing changes, thus the numbers 1 of the throughput in each gap below the diagonal D or in each row above the diagonal D which divides the matrix, it results as to which pumps are hydraulically connected in parallel and which are hydraulically connected in series. An equal number as occurs for example in the columns q7 and q6 and q5 in
Moreover, one may ascertain which of the pumps are directly assigned to a consumer or to a consumer group, and here it is specifically the case of the pumps with which no increasing change of the hydraulic variables in a row below the diagonal or a column above the diagonal of the matrix is plotted. This for example applies to the pump PU7, in whose associated rows in
Moreover, in
In an analogous manner, the evaluation of the matrix according to
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 000 446.4 | Jan 2010 | EP | regional |
