EP2039939A1 - Method for monitoring an energy conversion device - Google Patents

Abstract

The method involves detecting or calculating performance-based sizes of a functional unit automatically in time intervals. The performance-based sizes of a functional unit are compared with each other or with pre-set values. A corresponding signal is generated depending on the comparison. The energy conversion device consists of multiple functionally interrelated functional units. Independent claims are included for the following: (1) a rotary pump aggregate with an electric motor and a driven rotary pump; (2) a compressor aggregate with an electric motor and a driven displacement pump; (3) a cooling aggregate with an electric motor and a driven displacement pump; and (4) a heating system with a burner and one of the heated water circulations.

Description

The invention relates to a method for monitoring an energy conversion device, which consists of several functionally linked functional units. Such energy conversion devices in the context of the invention may be, for example, electric motor driven centrifugal pump units, electric motor driven compressors, equipment equipped therewith or the like. They consist of several functionally linked functional units, such as electric motor and centrifugal pump or electric motor and positive displacement pump or combustion engine and electric generator. Such energy conversion devices are used today in almost all technical but also domestic applications.

Although, in the course of dwindling resources, efforts are always made to build machinery, equipment or other energy conversion facilities so that they work with the highest possible efficiency for a long time, but in practice often poses the problem that the initial high efficiencies diminish and the Device continues to operate, although it no longer has the desired efficiency for a long time. This phenomenon can be observed, for example, in heating circulation pumps or in refrigerators. An exchange typically only occurs if a defect is evident or if the device completely fails the designated service.

In many such cases, however, it would make economic sense to replace the device beforehand or at least to replace or repair the defective or defective functional unit.

Against this background, the solution according to the invention provides for a method for monitoring an energy conversion device, which consists of a plurality of functionally linked functional units, in which power-dependent variables of at least one functional unit are automatically detected and / or calculated at time intervals and with each other or with them derived values and / or are compared with predetermined values and a corresponding signal is generated depending on this comparison. Based on this signal can then be determined whether the device is still working with the desired effectiveness, possibly provide one or more functional units insufficient performance or work with a reduced efficiency and thus determined whether the device is repair or replace.

The basic idea of the method according to the invention is to monitor at least one functional unit at intervals with regard to its efficiency and to display the result by means of a signal or to make it automatically evaluable. In the simplest form, power-dependent variables of a functional unit are automatically detected at intervals over time and compared with predetermined values determined beforehand or derived therefrom. Thus, for example, by comparing a performance-dependent variable of one of its functional units determined immediately after the device has been put into operation and comparing it with predetermined values, it can be determined whether the factory-provided performance is actually provided or not. It can then in further, preferably larger time intervals by comparing at least one performance-dependent Size are determined whether and to what extent the efficiency of the functional unit has deteriorated. It is advantageous according to the invention, not only one, but it is suitably monitored all the efficiency of the device substantially determining functional units in the manner described above. By monitoring the performance and corresponding signal processing, an energy conversion device, ie in particular an aggregate, a machine or a system can self-learning determine and display its individual performance characteristics, the resulting operating behavior, life expectancy and the like.

Performance-dependent variables in the sense of the present invention are those which stand in some connection with the performance characteristic of a functional unit. Thus, for example, in discontinuously operating units, such as the compressor of a refrigerator, and the timing of the switching on and off a performance-dependent size in the sense of the present invention.

Advantageous embodiments of the method according to the invention as well as devices operating according to the method of the invention are specified in the further claims and the following description and drawing.

According to an advantageous development of the invention, performance-dependent variables of at least two functionally linked functional units, preferably of all functional units, are automatically recorded and / or calculated at intervals, wherein the power-dependent output variables or variables derived therefrom of one functional unit form the power-dependent input variables of the function unit downstream of this functionally.

By means of this combination mathematical models can be used in the calculation and the above-mentioned monitoring tasks can be reliably ensured on the basis of only comparatively less measurable variables.

The efficiency monitoring according to the invention of the device or at least individual functional units of the device can be carried out comparatively easily if the functional units always run at the same operating point, since then typically one measured value is sufficient to determine the intended or degraded power / efficiency of the respective unit. However, this is more complicated if an energy conversion device such as a heating circulation pump is to be monitored. Such aggregates typically consist of the functional units engine and centrifugal pump, wherein the centrifugal pump typically constantly changes its operating point, since the pipe network resistance of the heating system changes due to external influences. In order to have comparable performance-dependent variables here, it is expedient to use the variables resulting from a mechanical-mechanical model of the motor and the parameters resulting from a mechanical-hydraulic pump model at the interface between the motor and the pump in order to determine the power level of the pump unit in this manner , Alternatively, the determination can also take place in that two hydraulic variables of the pump, typically the flow rate and the delivery head, are determined and equated with the mechanical output delivered by the engine via a corresponding model calculation.

It is particularly advantageous in such facilities, in which the operating points change constantly and is therefore assumed that in temporally spaced measurements of all probability not the same operating point is reached again, in short time distance perform several measurements and determine based on the operating points thus determined performance-dependent, possibly multi-dimensional surface curves at the interfaces of the functional units to each other and to compare with previously determined. In this case, these calculated surfaces are advantageously approximated using a Kálmán filter, so that even with comparatively few measurements, the respective performance-determining surface can be determined with sufficient accuracy. It can then be used as a measure of the change in efficiency, typically the efficiency drop, the distance of such surfaces determined at a longer time interval at a certain operating point or the volume spanned between the surfaces.

Advantageously, the method according to the invention is carried out during the normal operation of the device, ie in a pump unit during the intended conveying operation, the time interval for detecting the quasi-simultaneous operating points for determining the course of the area being in the range of, for example, minutes, whereas the time interval after a comparative measurement is performed, may be in the daily, weekly or monthly range, depending on the device type. Comparatively long intervals are z. As result in heating circulation pumps, whereas short intervals in compressors, especially for cooling systems may be appropriate because with such a monitoring method not only a deterioration in efficiency, but also a possible expected failure of the device can be detected.

The time interval in which the performance-dependent variables to be compared are thus determined depends both on the type of machine and on the intended use. However, the comparison is expediently made on the basis of the variables previously recorded or predetermined values, the latter method having the advantage has that thus already a malfunction is detectable at startup.

With significantly lower metrological and computational effort, the method according to the invention can be carried out when first an electrical motor size determining the power consumption of the motor and at least one size determining the hydraulic operating point of the pump are recorded and stored and is maintained for the later comparison measurement, until the previously detected hydraulic operating point is reached again and then the power consumption of the engine determining quantities of the engine are detected and compared with the first stored. Then, a direct comparison can be made without operating point deviations and thus the aforementioned surface curves must be determined.

Alternatively, the variables acquired later for comparison measurement can also be detected at any operating point of the installation if the acquired variables are transferred based on a mathematical electrical motor model and / or a mathematical-hydraulic pump model, i. be converted to operating point independent variables and then compared with the stored variables or vice versa, so that a comparison of the power-determining variables is possible regardless of the operating point.

Advantageously, according to the invention, the method is used only after a predetermined time has elapsed, this predetermined time corresponding at least to the running-in time of the unit, in particular of the pump unit. This is useful so that the mechanical parts of the unit set, any Einfahrwiderstände be overcome in the camps and then after the break-in a first quasi stationary operating state can be achieved, which forms a basis for the normal performance-determining properties of the device, so that only deviations from this state are detected later.

It is particularly advantageous if after expiry of the predetermined time, ie typically the break-in time automatically detected at least one operating profile and determines the expected energy consumption taking into account the possibly determined efficiency change and displayed by suitable means. With this method, it is possible to automatically determine after the break-in period whether the unit will meet the values specified in terms of performance / efficiency or what additional changes in energy consumption will be expected due to a deterioration in efficiency.

According to an advantageous development of the method according to the invention, it is not necessary for a comparison measurement to approach the same operating point. On the basis of several operating points, a surface course having a multidimensional model character and dependent on the performance of a functional unit can be determined and stored again at temporal intervals and stored and compared with the or a previously determined one, in which case the spacing of the surface curves in FIG a predetermined operating point or operating range or the volume spanned between the surface curves are used as a measure of the change in efficiency. Such an evaluation is particularly advantageous because it can be done during continuous operation without any intervention in the performance of the machine. Such a method is particularly advantageous in centrifugal pump units, as used for example as heating circulation pumps, which usually run on constantly changing operating points. To determine the course of the surface on the basis of the operating points, a Kálmán filter is advantageously used used. This iteration method makes it possible to determine the course of the area sufficiently accurately with only a comparatively small number of measured operating points in order to be able to detect the deviations in question and to be able to determine them quantitatively.

In principle, the method according to the invention can be used for monitoring any energy conversion devices that consist of a plurality of functionally linked functional units. Particularly advantageous is the use of centrifugal pump units, compressors, heating systems, refrigerators, freezers and the like, which are typically operated over years and decades, without a decrease in efficiency would notice or announces a failure. Thus, the monitoring method according to the invention is both suitable for detecting and displaying a poor running, ie a deterioration in efficiency, which makes early replacement of the unit or at least one functional unit of the unit appear economically sensible, as well as, for example, in freezers or freezers of particular advantage to be able to display the anticipated failure of the unit to provide timely replacement. Even with larger machines whose stoppage entails economic consequences, the inventive method can be used effectively to indicate an imminent failure in advance. It goes without saying that corresponding characteristic values are then suitably specified which were previously determined in the laboratory test, so that the downtime can at least roughly be determined on the basis of the change in efficiency or the change in performance of the machine.

The inventive method can advantageously in the form of a software program in the case of modern units anyway digital control electronics are implemented. In pump units and compressors, such control and regulating electronics can be provided both in the unit itself and in the terminal or terminal box of the unit.

Advantageously, the method according to the invention is applied to a centrifugal pump assembly with an electric motor and a centrifugal pump driven therefrom in a device provided therein for monitoring the power characteristic of at least one functional unit of the unit. Even with a compressor unit with an electric motor and a positive displacement pump driven therefrom, such a device according to the invention for monitoring the power characteristic, in particular for the efficiency detection and monitoring can be provided. Advantageously, a cooling unit can be provided with an electric motor, with a positive displacement pump driven therefrom, with an evaporator and with a capacitor with a device for monitoring the performance, which operates according to the inventive method, wherein the monitoring of the performance characteristics not only on engine and Positive displacement pump limited, but advantageous evaporator and condenser includes.

In particular, in refrigerators, a reduction in the efficiency is determined by the fact that the duration of the compressor is monitored after installation of the device. This can be done, for example, by determining the running time within 24 hours and then comparing it later, for example after six months, with the resulting runtime within 24 hours. It can be assumed in the simplest form that due to constant environmental conditions and user behavior an increasing duty cycle by a deterioration in efficiency the system is conditional. More precise conclusions can be determined by an analysis of the time course of the compressor runtime.

In an analogous manner, in a heating system, a device for monitoring the performance of the burner and at least one of these heated water cycle may be provided in order to detect in this way, for example, combustion residues on the primary heat exchanger and concomitant efficiency deterioration. Here, by attaching a corresponding signal lamp thus also an indication of the required cleaning service will be given, which can thus be determined as needed.

Appropriately, the device is designed so that it automatically starts after a predetermined time after commissioning of the unit or the system with the detection and storage for monitoring the performance characteristics, in particular for determining the effectiveness and monitoring sizes and at appropriate intervals again these sizes recorded and compared with the pre-stored and / or the originally stored variables and displays a possibly impermissibly high deviation. According to an embodiment of the invention, the device therefore advantageously has a measured value memory in which at least the variables detected at the beginning of the measurement or variables derived therefrom are stored.

Appropriately, the machine is monitored as far as possible in its entirety by the method according to the invention. However, it may also be sufficient to monitor only one functional unit of the machine. This will be particularly useful if the machine has a functional unit, which typically significantly before all other functional units due to wear or otherwise fails.

It is particularly advantageous if several or preferably all functional units of an energy conversion device, ie a machine, an aggregate or a system, are detected in order to be able to allocate these selectively to one or more functional units in the event of a deterioration in efficiency, and then selectively only this functional unit or functional units repair or replace. This will be economically viable, especially for larger machines.

Fig. 1

anhand eines Schaubilds das grundlegende Prinzip eines mit Leistungsflächen arbeitenden erfindungsgemäßen Überwachungsverfahrens,

Fig. 2 a

das Überwachungsverfahren nach Fig. 1, dargestellt anhand eines Kreiselpumpenaggregates,

Fig. 2 b

ein alternatives Überwachungsverfahren für eine Kreiselpumpe,

Fig. 2 c

eine weitere Variante eines Überwachungsverfahrens für eine Kreiselpumpe,

Fig.3

ein Überwachungsverfahren, dargestellt anhand eines Kompressors,

Fig. 4

ein Überwachungsverfahren, dargestellt anhand eines Kühlgeräts und

Fig. 5

ein Überwachungsverfahren, dargestellt anhand einer Heizungsanlage.

The invention is explained in more detail with reference to embodiments shown in the drawing. Show it:

Fig. 1

on the basis of a diagram, the basic principle of a monitoring system operating according to the invention with power surfaces,

Fig. 2 a

the monitoring process Fig. 1 represented by a centrifugal pump assembly,

Fig. 2 b

an alternative monitoring method for a centrifugal pump,

Fig. 2 c

a further variant of a monitoring method for a centrifugal pump,

Figure 3

a monitoring method, represented by a compressor,

Fig. 4

a monitoring method, illustrated by means of a refrigerator and

Fig. 5

a monitoring procedure, represented by a heating system.

In Fig. 1 is an energy conversion device consisting of the functional units 1 and 2 shown by way of example for a variety of machines, systems and units. In the illustrated embodiment, the functional units 1 and 2 are monitored independently. In this case, first of all the power P _{1 received} by the functional unit 1 is dependent on one or more variables x ₁ recorded and stored, as in Fig. 1 represented by 3. The variables x ₁ are through u ₁ and y ₁ , so that the area shown in FIG. 3 corresponds to the energy balance of the functional unit 1 at the entrance. Accordingly, a power P ₂ sets in at the output, which in turn depends on the variables x ₁ is. This area is shown in FIG. The functional units 1 and 2 are functional, z. B. via a shaft connected to each other, which is why the representation 4 of the representation 5 corresponds to the power P ₂ here in dependence on x _{2 defined} according to the energy balance at the input of the functional unit 2, depending on the variables u ₂ and y ₂ . At the output of the functional unit 2 is a power P ₃ , as shown in FIG. 6 and dependent on x _{2 is} 2.

The surfaces marked by hatching in FIGS. 3 to 6 are determined at the beginning of the method. This can be factory-made or only after some time in operation. This can be done as an initialization process or during operation. In any case, it takes place at a time t ₁ , which, if several operating points are to be detected, can also represent a time range.

At a time t ₂ , an energy balance at the input of the functional unit 1, at the output of the functional unit 1, at the input of the functional unit 2 and at the output of the functional unit 2 is then created in the same way. The corresponding representations are marked 3 ', 4', 5 'and 6'. By comparing these at the time t ₂ , which may also be a time range, determined sizes or areas with the determined and stored at time t ₁ sizes or areas efficiency reductions of individual functional units 1, 2 can be detected wherein the distance of the hatched areas in 3 and 3 'or 4 and 4' or 5 and 5 'or 6 and 6' is determined at a predetermined operating point or the volume spanned between these surfaces is determined and a signal is generated which is identified to the user when a predetermined value is exceeded makes a deterioration in efficiency take place in the machine which makes replacement or repair or immediate replacement or repair appear expedient. Here, by grading the values, different signals may be generated, for example, a first warning signal indicative of a certain level of reduced efficiency and a second warning signal indicative of such a reduction in efficiency requiring replacement or repair. Since the functional units 1 and 2 are monitored separately from one another, it can furthermore be determined which of the functional units is wholly or partially responsible for the reduction in efficiency.

How this can look like in a specific application is, for example, based on Fig. 2 a, b and c shown. Shown there is a device consisting of an electric motor 1a and a pump 2a, which feeds a consumer 7. The electrical power absorbed by the motor 1a is indicated by P ₁ . The motor converts the electric power into a torque T _e at a rotational speed ω _r . This am Output of the motor 1a pending mechanical power P _{2 also} represents the pending at the entrance of the pump 2a mechanical power P ₂ , which is converted within the pump into a hydraulic power P ₃ , by the pressure difference generated by the pump between the suction and discharge side Δ p and the flow rate through the pump q is determined. To the on the basis of Fig. 2a From device 1 a and pump 2a to fully monitor existing device, it is expedient to determine at the respective interfaces surfaces, which includes the power of the respective functional unit in each possible operating point, respectively at the input and at the output thereof.
The formulaic relationship is as follows:

Variable:

• q ~ Flow rate through the pump [m ³ / h]
• Δ p ~ differential pressure built up by the pump [bar]
• ω _r ~ speed of the shaft driving the pump [rev / sec]
• T _e ~ Torque of the shaft [Nm]
• V ~ supply voltage [V]
• I ~ supply current [A]
• φ ~ angle between the supply voltage V and the motor current l [U]
• ω _e ~ supply frequency [U / sec]
• P ₁ ~ electric power supplied to the motor [W]
• P ₂ ~ mechanical power at the motor shaft [W]. The power P ₂ is proportional to the slip s of the motor. This is P ₂ α s .
• P ₃ ~ hydraulic power of the pump [W]
• η _m ~ motor efficiency
• η _p ~ pump efficiency

$$P_I=\mathit{VI}\cos \left(\mathrm{\phi }\right)$$

$$P_2={\omega }_r{T}_e$$

$$P_3=\mathit{\kappa q}\mathrm{\Delta }p$$

$${\mathrm{\eta }}_m=\frac{P_2}{P_1}$$

$${\mathrm{\eta }}_p=\frac{P_3}{P_2}$$

These variables are linked as follows: $$s=\frac{{\mathrm{\omega }}_e-{\mathrm{\omega }}_r}{{\mathrm{\omega }}_e}$$

$$P_I=\mathit{VI}\cos \left(\mathrm{\phi }\right)$$

$${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\omega }_r{T}_{\mathrm{<figure-callout\; id="3"\; label="e\; P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">e\; </figure-callout>}}$$

$$P_{}$$$${}_3=\mathit{\kappa q}\mathrm{\Delta }p$$

$${\mathrm{\eta }}_m=\frac{P_2}{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}$$

$${\mathrm{\eta }}_p=\frac{P_3}{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2}$$

wobei vorausgesetzt wird, dass die Versorgungsspannung durch den Vektor $\left[\begin{array}{c}{\mathit{V}}_{\mathit{sd}}\\ {\mathit{V}}_{\mathit{sq}}\end{array}\right]=\left[\begin{array}{c}{K}_1{\mathit{\omega }}_e+K_0\\ 0\end{array}\right]$

gegeben ist. R_s (Statorwiderstand), L _Is (induktive Verluste des Stators), L_m (magnetische Induktion), L_Ir (induktive Verluste des Rotors), R_r (Rotorwiderstand) und $\mathrm{J}\left(\mathrm{Matrix}\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]\right)$

sind die Konstanten des Motors.The mathematical description of the area of performance of the engine in all operating points defining surface according to representation 8 thus results from the following equation: $${\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">P</figure-callout>}}_1\left({\mathrm{\omega }}_{e}s\right)=v_s•[I{R}_s+J{\mathit{\omega }}_e\left(L_{\mathit{ls}}+L_m\right)-J{\mathit{\omega }}_e{L}_m(\frac{R_r}{s}+J{\mathit{\omega }}_e\left(L_{\mathit{lr}}+L_m\right){)}^{-1}J{\mathit{\omega }}_e{L}_m{]}^{-1}{v}_s$$

assuming that the supply voltage through the vector $\left[\begin{array}{c}{\mathit{V}}_{\mathit{sd}}\\ {\mathit{V}}_{\mathit{sq}}\end{array}\right]=\left[\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">K</figure-callout>}}_1{\mathit{\omega }}_e+{\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">K</figure-callout>}}_0\\ 0\end{array}\right]$

given is. R _s (stator resistance), L _{I s} (inductive losses of the stator), L _m (magnetic induction), L _Ir (inductive losses of the rotor), R _r (rotor resistance) and $\mathrm{J}\left(\mathrm{matrix}\left[\begin{array}{cc}0& -1\\ 1& 0\end{array}\right]\right)$

are the constants of the engine.

beschrieben werden, in welcher die Konstanten α _T2 , α _T1 , α _T0 und B Pumpenkonstanten sind.The power at the inlet of the pump 2a according to illustration 9 can be known by the pump equation $$P_2\left(q{\omega }_r\right)=-a_{P2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2{\omega }_r+a_{P2}{q\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+a_{P0}{\omega }_{\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^3+B{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2$$

in which the constants α _T2 , α _T1 , α _T0 and B are pump constants.

The power present at the output of the pump 2a as shown in FIG. 10 can be described by the following equation: $$P_3\left(q{\omega }_r\right)=-a_{p2}{\mathrm{<figure-callout\; id="3"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^3+a_{p2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2{\omega }_r+a_{p0}q{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+p_{\mathit{offset}}q$$

In this equation, the constants are α _p2 , α _p1 , α _p0 and p _offset .

Based on the illustrations 8, 9 and 10 in Fig. 2a illustrated three-dimensional areas, which describe the power at the interfaces before, between and behind the functional units 1a and 2a, respectively, are detected and stored at a time t ₁ . The detection typically occurs during normal operation for a short period of time which is negligibly small with respect to the monitoring interval (time from T ₁ to t ₂ ), after which, after a longer period of time, namely at time t _2, this process is repeated so that the surfaces according to the representations 8 ', 9' and 10 'result. The surfaces 8 and 8 'as well as 9 and 9' and finally 10 and 10 'are compared with one another at the time t ₁ and t ₂ . If the surfaces match, the unit will work unchanged. On the other hand, if two of these surfaces are spaced apart at one operating point, then one of the functional units has changed in performance, typically deteriorating. Thus, if, for example, a distance between the surfaces according to FIGS. 10 and 10 'and otherwise coincident surfaces are determined, then it can be assumed that, although the motor 1a operates with undiminished efficiency, that within the pump 2a has taken place an efficiency changing process. Conversely, with a change in the surfaces according to the representations 9 and 9 'for constant pump performance characteristic but changed engine efficiency can be concluded.

In monitoring as they are based on Fig. 2a is shown, there is a performance monitoring in front of and behind each functional unit 1a, 2a. However, this can be dispensable depending on the application. Also, it is not absolutely necessary to determine the surface curves having the multi-dimensional and model character representing the input or output power, as defined by equations 8, 9 and 10, but rather, like the embodiment according to FIG Fig. 2b clarified, for example, in place of the power P ₃ as shown in Figure 10 in Fig. 2a Alternatively, the hydraulic power characteristic can be determined, that is, the differential pressure applied by the pump 2a as a function of the drive speed ω _r and the flow rate q. Which is detected and stored at time t ₁ . The multi-dimensional area listed in FIG. 10 a and the area listed at time t ₂ in representation 10 a 'are each defined by the equation. $$\mathrm{\Delta }p\left(q{\omega }_r\right)=-a_{p2}{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">q</figure-callout>}}^2+a_{p2}{\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">q</figure-callout>}}^1{\omega }_r+a_{p0}q{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+p_{\mathit{offset}}$$

Based on Fig. 2c is another way of monitoring such a pump unit consisting of the functional units 1a and 2a shown. As illustrated in FIG. 11, the power P _{1 is} detected there as a function of ω _e and Q as shown in FIG. 8 a and is compared with the corresponding power as shown in FIG. 8 a 'at a time interval between t ₁ and t ₂ . Also, the power P ₂ is determined there as a function of Δ _p and ω _r , as the illustration according to 9a or 9a 'illustrates. Finally, in the case of FIG. 2c monitoring concept shown, the efficiency of the motor η _m and the efficiency of the pump η _p directly monitored, as the representations 11 a and 11 b and 11 a 'and 11 b' illustrate. These differences are merely intended to clarify that there are a large number of possibilities for monitoring the performance characteristics of the entire device but also the functional units thereof, as has been explained above with reference to the centrifugal pump assembly consisting of the functional units motor 1a and pump 2a.

The efficiency of the motor η _m is the quotient of P ₂ and P ₁ and is dependent on ω _e (the supply frequency) and s , the slip of the motor. The motor efficiency is in Fig. 2c in the representation 11 a represented by the area in the diagram in each operating point. In the illustration 9a shows the power P ₂ in response to Δ p and q is shown. This results in the efficiency of the pump η _p as a function of the pump speed (ω _r ) and the delivery rate q , as illustrated by the surface shown in FIG. 11b. In Fig. 8a, the power P _{1 of} the motor 1a is also represented in the form of a surface as a function of the supply frequency and the flow rate of the pump. Analogous to Fig. 1 are the basis of the surfaces 8a, 9a, 11a and 11b shown performances and efficiencies at time t _{1 were} determined and stored, whereas at time t ₂ corresponding comparison surfaces have been determined, as a measure of the change in efficiency of the distance of the surfaces in the representations 11 a and 11 a 'and 11 b and 11 b' are used. If, for example, the efficiency of the pump 2a decreases in the course of time t ₁ to t ₂ due to bearing damage, the areas in the representations 11a and 11a 'will be in one another, whereas the areas in the representations 11b and 11b' will be at a considerable distance from each other, based on an operating point. Instead of this distance, a volume can also be defined.

• p_in ∼ Eingangsdruck am Kompressor [bar]
• p_out ∼ Ausgangsdruck am Kompressor [bar]
• T_in ∼ Eingangstemperatur am Kompressor [°K]
• T_out ∼ Ausgangstemperatur am Kompressor [°K]
• ω_r ∼ Drehzahl der den Kompressor antreibenden Welle [U/sec]
• P₁ ∼ vom Motor aufgenommene elektrische Leistung [W]
• P₂ ~ Leistung an der Antriebswelle [W]. Die Leistung P₂ ist proportional zum Schlupf des Motors s. Dies ist P₂ ∝ s.

Based on Fig. 3 shows by way of example how a compressor can be monitored with the method according to the invention. The compressor has a functional unit 1b in the form of a motor and a functional unit 2b driven in the form of a positive displacement pump which feeds a consumer 7b. Here, too, a surface representing the engine power according to illustration 12 and a surface representing the pump power are determined and stored at a time t ₁ and stored at a time interval, for example at time t ₂ , according to the representations 12 'and 13' on the basis of current values determined at the time t ₂ and compare with the stored, here too the distance of the surfaces according to the representations 12 and 12 'or 13 and 13' and the volume spanned therebetween is used as a measure of the efficiency deterioration. The computational relationships are as follows:

• p _in ~ inlet pressure at the compressor [bar]
• p _out ~ outlet pressure at the compressor [bar]
• T _in ~ inlet temperature at the compressor [° K ]
• T _out ~ Output temperature at the compressor [° K ]
• ω _r ~ speed of the shaft driving the compressor [rev / sec]
• P ₁ ~ electric power absorbed by the motor [W]
• P ₂ ~ Power at the drive shaft [W]. The power P ₂ is proportional to the slip of the motor s. This is P ₂ α s .

$$\frac{n-1}{n}=\frac{\ln \left(T_{\mathrm{out}}\right)-\ln \left(T_{\mathrm{in}}\right)}{\ln \left(p_{\mathrm{out}}\right)-\ln \left(p_{\mathrm{in}}\right)}$$

Furthermore, the following mathematical relationships apply: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\mathrm{\omega }}_r{T}_e$$

$$\frac{n-1}{n}=\frac{\ln \left(T_{\mathrm{out}}\right)-\ln \left(T_{\mathrm{in}}\right)}{\ln \left(p_{\mathrm{out}}\right)-\ln \left(p_{\mathrm{in}}\right)}$$

wobei k = ΔV/(2π) ist.For an adiabatic compression cycle, the power P ₂ is thus as follows: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">k</figure-callout>}}_0{\omega }_r{p}_{\mathit{in}}\ln \left(\frac{{\mathit{p}}_{\mathit{out}}}{{\mathit{p}}_{\mathit{in}}}\right)+{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">k</figure-callout>}}_1{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_2{\omega }_{\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^3$$

wherein k = Δ V / (2π).

wobei k = ΔV n/(n-1) /(2π), wobei n eine Konstante ungleich 1 ist, die den Wärmefluss während der Kompression beschreibt. Wenn der Prozess unter konstanter Temperatur abläuft, kann somit n ebenfalls als konstant angenommen werden. Der Ausdruck n/(n-1) ergibt sich aus folgender Gleichung: $$T_{\mathit{out}}=T_{\mathit{in}}(P_{\mathit{out}}/P_{\mathit{in}}{)}^{(n-1)/n}$$

If there is no adiabatic process in the compressor circuit, the power can be specified as follows: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">k</figure-callout>}}_0{\omega }_r{p}_{\mathit{in}}\left((\frac{{\mathit{p}}_{\mathit{out}}}{{\mathit{p}}_{\mathit{in}}}{)}^{\frac{n-1}{n}}-1\right)+{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">k</figure-callout>}}_1{\omega }_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}}_2{\omega }_{\mathrm{<figure-callout\; id="3"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^3.$$

where k = ΔV n / ( n -1) / (2π), where n is a non-1 constant that describes heat flow during compression. If the process runs under constant temperature, then n can also be assumed to be constant. The expression n / ( n -1) is given by the following equation: $$T_{\mathit{out}}=T_{\mathit{in}}(P_{\mathit{out}}/P_{\mathit{in}}{)}^{(n-1)/n}$$

This means that this expression can be determined from the temperatures T _in and T _out and the pressures P _out and P _in as follows: $$\frac{n-1}{n}=\frac{\ln \left(T_{\mathrm{out}}\right)-\ln \left(T_{\mathrm{in}}\right)}{\ln \left(p_{\mathrm{out}}\right)-\ln \left(p_{\mathrm{in}}\right)}$$

The engine power P ₁ can be monitored in an analogous manner as indicated above by equation (8).

Based on Fig. 4 is the inventive method for a refrigerator shown consisting of a motor 1 c, a positive displacement pump 2 c, the output of which acts on an evaporator 3 c, which is connected via a throttle 4 c with a capacitor 5 c, the output of which is line connected to the input of the pump 2 c. The refrigerator is marked 7c.

• T₁ ~ Temperatur am Austritt des Verdampfers 3c
• T_h ~ Temperatur am Eintritt des Kondensators 5c
• T_box ∼ Temperatur im Kühlraum 7c
• T_amb ~ Umgebungstemperatur
• Q ₁ ∼ Kühlleistung
• Q ₂ ~ an die Umgebung abgegebene Leistung
• W ~ von der Pumpe 2c abgegebene Leistung
• ω _r ~ Geschwindigkeit der Motorwelle [U/sec]
• T_e ~ Drehmoment [Nm]
• P₂ ~ vom Motor abgegebene mechanische Leistung

In this system the following variables result:

• T ₁ ~ temperature at the outlet of the evaporator 3c
• T _h ~ temperature at the inlet of the condenser 5c
• T _box ~ temperature in the refrigerator 7c
• T _amb ~ ambient temperature
• Q ₁ ~ cooling capacity
• Q ₂ ~ Power delivered to the environment
• W ~ output from the pump 2c
• ω _r ~ motor shaft speed [rev / sec]
• T _e ~ torque [Nm]
• P ₂ ~ mechanical power output by the engine

$$T_{\mathit{eq}}=\frac{T_h-T_l}{T_l}\cdot \left({\mathit{T}}_{\mathit{amb}}\mathit{-}{\mathit{T}}_{\mathit{box}}\right)$$

These are in the following mathematical context: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\mathrm{\omega }}_r{T}_e$$

$$T_{\mathit{eq}}=\frac{T_H-T_l}{T_l}\cdot \left({\mathit{T}}_{\mathit{amb}}\mathit{-}{\mathit{T}}_{\mathit{box}}\right)$$

$$P_3=R_{\mathit{th}}\cdot \frac{T_h-T_l}{T_l}\cdot \left({\mathit{T}}_{\mathit{amb}}\mathit{-}{\mathit{T}}_{\mathit{box}}\right)$$

The power of the motor 1 c descriptive surface according to representation 14 corresponds to that according to representation 12 in Fig. 3 or representation 8 in Fig. 2a For the areas P ₂ and P ₃ defining areas, the following relationships arise: $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=R_{\mathit{th}}\cdot \frac{T_H-T_l}{T_l}\cdot \left({\mathit{T}}_{\mathit{amb}}\mathit{-}{\mathit{T}}_{\mathit{box}}\right)+K_{\mathrm{\omega }}\cdot {\mathrm{\omega }}^3$$

$${\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_3=R_{\mathit{th}}\cdot \frac{T_H-T_l}{T_l}\cdot \left({\mathit{T}}_{\mathit{amb}}\mathit{-}{\mathit{T}}_{\mathit{box}}\right)$$

Equation 15 describes the power P ₂ at the input of the compressor whereas equation 17 describes the power at the output of the compressor. As illustrated in particular in FIG. 17, the areas to be determined here for determining the power at the interfaces of the functional units may be two-dimensional or multi-dimensional. The area according to illustration 17 is two-dimensional, ie a line. The other surfaces shown here are all three-dimensional. It is understood that these surfaces may possibly be more than three-dimensional, depending on the type of machine to be monitored and the underlying mathematical physical relationships.

Again, the monitoring is carried out in an analogous manner by determining the power at the interfaces of the functional units surfaces according to representations 14, 15 and 17 at time t ₁ and after a time interval at time t ₂ (then resulting in the surfaces according to the Representations 14 '15' and 17 '), to then determine by determining the distance of the surfaces or the volume spanned therebetween, which of the functional units 1 c, 2 c, by which degree have fallen in their efficiency.

• q ~ Volumenstrom des durch die Leitung 22 strömenden Wassers
• ṁ_g ~ Abgasmasse
• T_w,out ∼ die Temperatur des aus der Leitung 22 austretenden Wassers
• T_w,in ~ die Temperatur des in die Leitung 22 eintretenden Wassers
• T_g,out ∼ die Temperatur des Abgases am Austritt
• T_g,in ~ die Verbrennungstemperatur
• T_amb ~ die Umgebungstemperatur
• P₁ ~ die durch den Brennstoff in das System eingebrachte Leistung
• P₂ ∼ die durch das Wasser aus dem System abgeführte Leistung

Finally, based on Fig. 5 illustrated how the monitoring method according to the invention is applicable to the primary circuit of a heating system. The heating system has a burner 20, which heats water in a combustion chamber 21 in a line 22. The heated water from the burner 20 is guided in the primary circuit of the heating system and arrives after dissipating its heat in a heat exchanger 23, in which the exiting the combustion chamber 21 exhaust gas gives off its heat to the water. The exhaust gas passes through the outlet 24 into the open. The variables of this system are:

• q ~ volume flow of the water flowing through the conduit 22
• ṁ _g ~ exhaust mass
• T _{w, out} ~ the temperature of the emerging from the line 22 water
• T _{w, in} ~ the temperature of entering the line 22 water
• T _{g, out} ~ the temperature of the exhaust gas at the outlet
• T _{g, in} ~ the combustion temperature
• T _amb ~ the ambient temperature
• P ₁ ~ the power introduced into the system by the fuel
• P ₂ ~ the power dissipated by the water from the system

This results in the following relationships: $${\mathit{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2\mathit{=}{\mathit{\rho }}_w{\mathit{q\; C}}_{\mathit{pw}}\left({\mathit{T}}_{\mathit{w}\mathit{.}\mathit{out}}\mathit{-}{\mathit{T}}_{\mathit{w}\mathit{.}\mathit{in}}\right)$$

wobei C_pg und C_pw die spezifische Wärmekapazität des Abgases, U der Wärmeübertragungskoeffizient und A die Wärmeübertragungsfläche zwischen dem Brenner 20 und der Leitung 22 sind. Dabei werden die durch das Abgas abgeführte Leistung P _in und der Massestrom ṁ _g des Abgases als konstant angenommen, ebenso die Umgebungstemperatur T _amb. Ggf. können diese Größen auch in einfacher Weise durch Messung ermittelt werden.where ρ _{w is} the density of the water and C _{pw is} the specific heat capacity of the water. The surfaces to be calculated in this case are as follows and are indicated at time t ₁ by representation 16 and at time t ₂ by representation 16 ': $${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\tilde{P}}_1-{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}{T}_{w.\mathit{in}}-{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}\left({\tilde{T}}_{G.\mathit{in}}-T_{w.\mathit{out}}\right)e^{-\frac{\mathit{UA}}{{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}}-\frac{\mathit{UA}}{q{\rho }_G{C}_{\mathit{pw}}}}+{\tilde{\dot{m}}}_G{C}_{\mathit{pg}}{\tilde{T}}_{\mathit{amb}}$$

where C _pg and C _{pw are} the specific heat capacity of the exhaust gas, U is the heat transfer coefficient and A is the heat transfer area between the burner 20 and the conduit 22. Here are the power dissipated by the exhaust gas P _in and the mass flow m ' _{g of} the exhaust gas assumed constant, as well as the ambient temperature T _amb . Possibly. These sizes can also be determined in a simple manner by measurement.

As the above embodiments illustrate, the inventive method can be used in a variety of devices such as aggregates, machines and equipment, which advantageously always the multi-dimensional surfaces are determined, each defining the power at the interfaces of the functional units to each other in any operating point and thus a reliable Measure for the performance characteristics of the functional units and with appropriate evaluation of the entire device, if they are compared at different times (eg, t ₁ and t ₂ ). It is understood that the times t ₁ and t _{2 are} here to be understood as examples only, expediently the values determined at time t ₁ always remain stored in order to be able to compare them with later ones, which however does not rule out that intermediate values are also stored if necessary, also to record the speed of the change. This too can be evaluated in a corresponding evaluation device. In that regard, in particular EP 1 564 411 A1 referred where comparable evaluations are described in detail.

It should be noted at this point that in the exemplary embodiments illustrated above, two-dimensional or more-dimensional surfaces have always been used to determine the power balance at the interfaces of the functional units, since this allows an evaluation virtually independent of the respective operating point. At substantially constant operating points, these evaluations can also take place in a simplified manner by comparing individual variables with one another over the time interval, indirectly or directly Conclusions about the efficiency can be made. The two- or multi-dimensional surfaces in question are advantageously determined during operation, whereby it is attempted by suitable iteration methods to achieve a high accuracy of the surfaces on the basis of as few as possible different operating points. This can be achieved in particular by using the Kálmánfilters, as has already been described above. However, other suitable iteration methods may be used. It is also conceivable that, for example, in a pump unit, certain operating points are approached targeted to capture the power balance representing surface area with the highest possible accuracy or to dispense with targeted detection of defined operating points on the determination of such areas.

Claims (19)

Method for monitoring an energy conversion device, which consists of a plurality of functionally interconnected functional units, in which power-dependent variables of at least one functional unit are automatically detected and / or calculated at time intervals and compared with each other or with values derived therefrom and / or with predetermined values and in dependence the comparison a corresponding signal is generated. Method according to Claim 1, in which power-dependent variables of at least two functionally linked functional units are automatically detected and / or calculated at intervals, wherein the power-dependent output variables or variables derived therefrom of one functional unit form the power-dependent input variables of the function unit downstream of this functionally. Method according to one of the preceding claims, in which comparison variables or comparison functions are formed on the basis of the power-dependent variables which are determined and suitable for operating point-independent power comparison. Method according to one of the preceding claims, in particular for optimizing the operation and / or monitoring the energy consumption or the efficiency of a pump unit, in particular an electric motor driven centrifugal pump unit, wherein in operation at least one power-dependent size of the motor and at least one hydraulic variable of the pump or at least two hydraulic Sizes of the pump at a time interval with each other or by a mathematical linkage thereof or are compared with predetermined values, and depending on the comparison, a signal indicative of the operating state of the pump unit is generated. A method according to claim 4, which is carried out during the intended conveying operation. Method according to one of the preceding claims, which is repeated at time intervals, wherein the comparison is performed on the basis of the previously detected quantities or the predetermined values. Method according to one of the preceding claims, in which first the power consumption of the motor determining electrical variables of the motor and at least one of the hydraulic operating point of the pump determining variable are detected and stored, and in which at a time interval upon reaching a previously detected corresponding hydraulic operating point detects the power of the motor-determining electrical variables of the motor and compared with the initially stored variables, after which a corresponding signal is generated. Method according to one of the preceding claims, in which first the quantities determining the power of the motor and the hydraulic operating point of the pump are detected and stored, and in which after a time interval these quantities are again detected, the detected quantities on the basis of a mathematical electric motor model and / or a mathematically hydraulic pump model and then compared with the stored variables or vice versa, after which a corresponding signal is generated. Method according to one of the preceding claims, wherein the detection of power-determining variables of the motor and / or pump only after a predetermined time, which corresponds to at least the running-in time of the pump unit takes place. Method according to Claim 9, in which, after the expiry of the predetermined time during the monitoring phase, at least one operating profile is detected automatically and the expected energy consumption is determined taking into account the optionally determined change in efficiency. Method according to one of the preceding claims, in which based on several operating points of a dependent of the performance of a functional unit having multi-dimensional model character surface course is determined and stored, that at intervals such surface curves are determined again and compared with the previously determined. A method according to claim 11, wherein the distance of the surface curves at a predetermined operating point or the volume spanned between the surfaces is used as a measure of the change in efficiency, in particular an efficiency drop. Method according to Claim 12, in which a Kalman filter is used to determine the course of the area on the basis of the operating points. Centrifugal pump assembly with an electric motor and a driven centrifugal pump, characterized in that a device for monitoring the performance of at least one functional unit of the unit is provided which operates according to a method according to any one of the preceding claims. Compressor unit with an electric motor and a positive displacement pump driven thereon, characterized in that a device for monitoring the performance of at least one functional unit of the unit is provided, which operates according to a method according to one of the preceding claims. Cooling unit with an electric motor, with a positive displacement pump driven therefrom, with an evaporator and with a condenser, characterized in that a device for monitoring the performance of at least one functional unit of the unit is provided, which operates according to a method according to one of the preceding claims. Heating system with a burner and at least one of this heated water cycle, characterized in that a device for monitoring the performance of at least one functional unit of the system is provided, which operates according to a method according to one of the preceding claims. Unit / plant according to one of the preceding claims, characterized in that the device automatically begins after a predetermined time after commissioning of the unit / system with the detection and storage of the variables relevant to the determination of the efficiency. Unit / system according to claim 18, characterized in that the device has a measured value memory in which at least the quantities recorded at the beginning of the measurement or variables derived therefrom are stored.

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