EP2944821A1 - Method for the energy-optimized regulation of the speed of a pump unit - Google Patents

Abstract

The invention relates to a method for energy-optimal operation of an open pump system (1) for liquid transport, with at least one variable-speed pump unit (2), which conveys the liquid from a container (3). As a function of at least one system characteristic curve HA (Q, h) specified by the manufacturer, the volume-flow-specific energy consumption (PQ (Q, h) required for a delivery flow (Q) to be conveyed is evaluated by evaluating a mathematical function (FIG. PQ (n, h)) of the pump set (2), the one speed (n opt, n (Q opt, h)) is calculated, in which the volume flow-specific energy consumption (PQ (Q opt, h), PQ (n, h) ) is minimal. The pump set (2) is then operated at this calculated optimum speed (n opt, n (Q opt, h)).

Description

The present invention relates to a method for energy-optimized operation of an open pump system for liquid transport, with at least one variable-speed pump unit, which conveys the liquid from a container. In particular, the invention relates to a method for the energy-optimal operation of a wastewater from a pump sump of a pumping station promotional, variable speed pump unit.

Pump sumps form intermediate collectors, into which the wastewater flows in via one or more inlets. The inlet or the inlets are sewer sewers. Depending on the size of this pump sump this summarizes one or more pumps that pump the wastewater from the pump sump via a pressure line in a geodetically higher drain line. This drain line can also be a sewer of the sewer system and lead, for example, in a next intermediate collector or to a sewage treatment plant.

The pump units in such sewage pumping stations are nowadays predominantly unregulated or operated by means of two-step control, in which the pump is switched on and off only cyclically or as needed. The activation and deactivation takes place depending on the water level in the pump sump, for example controlled by a float. Frequent on-off changes, however, lead to increased wear of the pump units and increased energy consumption.

However, pump stations are also known whose pump units have frequency converters for speed control, so that the pump can be regulated as needed. Such a sewage pumping station is for example from the German patent application DE 10 2013 007 026.0 known.

The WO 2005/088134 A1 describes a method for controlling a pumping station, in which the rotational speed of the pump is selected optimally in terms of energy level with regard to the filling level in the pump sump. However, this only applies to the current time. With regard to a future course of business, the in WO 2005/088134 A1 shown operation not energetically optimal.

With regard to the energy consumption of the pump unit, it can be stated that the share of energy costs in the life-cycle costs of wastewater pumps is very high at around 40% to around 80% energy costs, both with low and high operating times. Strong acceleration processes or the operation of the pump at high speeds while the medium to be transported is heavily burdened with general cargo, lead to high energy consumption, which would not necessarily be necessary.

The challenge of more energy-efficient control is open pump systems in general.

It is therefore an object of the invention to provide an operating method for an open pump system or for a liquid pumping from a container pump unit, which allows energy-optimized operation compared to the prior art and thus minimizing energy costs. It is therefore an object of the invention to energy-efficiently control a variable speed pump. In this case, an energy-optimal speed should be determined and applied.

This object is achieved by a method having the features of claim 1. Advantageous developments of the method are given in the dependent claims.

According to the invention, a method for energy-optimal operation of an open pump system for liquid transport, proposed with at least one variable speed pump unit, which promotes the liquid from a container, depending on at least one factory given system characteristic curve by evaluating a mathematical function, the one to be conveyed flow required for this Associates volume flow specific energy consumption of the pump set, the one speed is calculated at which the volume flow specific power consumption is minimal, and the pump unit is operated with this calculated speed as the optimum speed.

The pump unit is thus at least unless there is an exceptional operating situation that requires a different operating setting, always operated at the speed that leads to a minimum energy consumption.

The method is applicable to all open pump systems, i. such pump systems that do not promote in a closed circuit. In particular, the method according to the invention is suitable for the operation of a wastewater from a pump sump of a pumping station, which is capable of speed-controllable pump unit. Another application is, for example, the operation of a well pump that pumps groundwater out of a wellbore.

It should be noted that in addition to water any liquids can be promoted. The container for the liquid may be any open or closed, natural or artificial liquid holding site, in particular a sump, a well, a well, basin, tank, a cistern, a reservoir, a lake, or a collector.

Figur 1:

eine Pumpstation mit einem Pumpensumpf und darin angeordnetem Pumpenaggregat

Figur 2:

Ablaufdiagramm des Verfahrens

Figur 3:

Ablaufdiagramm des übergeordneten Verfahrens

Figur 4:

Grafische Darstellung des spezifischen Energieverbrauchs

Figur 5:

Darstellung des zeitlichen Verlaufs des gemessenen Förderstroms bei optimaler Drehzahl.

The method will be described below with reference to an embodiment using the attached figures, which relates to a wastewater pumping station. However, the specific embodiment can be generalized to any pump systems. Show it:

FIG. 1:

a pumping station with a pump sump and pumping unit arranged therein

FIG. 2:

Flowchart of the method

FIG. 3:

Flowchart of the parent procedure

FIG. 4:

Graphical representation of the specific energy consumption

FIG. 5:

Representation of the time course of the measured flow at optimal speed.

For the equipment of a new or existing pumping station with a variable speed sewage pump, the exact quantification of the energy saving compared to the two-point control without frequency converter or an alternative variable-speed pump is of great importance. This can be done with the aid of the method according to the invention, especially as the system characteristic curve is known on the basis of the manufacturer's specification and does not have to be determined first during operation of the pumping station.

FIG. 1 shows a wastewater pumping station 1 comprising a pump sump 3 with an inlet 4 and a drain 5 and a pump sump 3 arranged in this pump unit 2, which is driven by an electric motor and whose speed can be controlled. Although only a single pump unit 2 is shown here, two or more pump units may also be present in the pump sump 3. The geometry of the pump sump 3 is assumed to be known. The pump unit 2 consists of a pump unit 2a and a driving electric motor 2b. It pumps via a pressure line 6 located in the pump sump 3 wastewater in the geodesically higher drain 5. From there, the wastewater flows on to a next pumping station, a receiving water or directly to a water treatment plant.

In the inlet 4, a volumetric flow sensor can be arranged, which measures over a progressive period, the inflowing via the inlet 4 in the sump 3 amount of water per unit time. However, it is also possible to calculate the inflow values from the level changes and the delivery flow Q of the pump unit 2. In this case, the volume flow sensor is not needed.

In contrast, a volumetric flow sensor 9 on the pressure side of the pump unit 2 is provided to measure the flow rate Q of the pump unit 2. Alternatively, the volume flow sensor 9 can also be arranged at a different location, in particular in the pressure line 6 or the outlet 5. Furthermore, it is also possible to calculate the delivery flow values. In this case, the volume flow sensor 9 is also not needed.

Furthermore, a fill level sensor 11, which measures the water level h, is located in the pump sump 3. A current level h is represented by the line 7. However, it is not absolutely necessary to determine the current water level in order to determine an optimum operating speed. Rather, it is also possible to work with a constant level for the calculation, since the consideration of the current water level only slightly improves the energy-optimal operation.

The speed control of the pump unit 2 is performed by a pump electronics in the form of an evaluation and control unit 8, which is connected via a control line to the pump unit 2, in particular its electric motor 2b and as here preferably via corresponding measuring lines with the volume flow sensor 9 and / or Level sensor 11 may be connected. It should be noted that the pump electronics 8 contrary to the representation in FIG. 1 may also be formed by an evaluation unit on the one hand and a structurally separate control unit on the other. These units can also be separated from each other locally.

The pump electronics 8 has a computer electronics to perform numerical calculations, and preferably also a measuring electronics in order to process measured values. The speed control of the pump unit 2 is carried out in a conventional manner by the control of a frequency converter, which acts on the electric motor 2b with a voltage required to achieve a desired speed suitable height and frequency. The frequency converter can be arranged directly structurally on the electric motor 2 b or also be part of the remote evaluation and control unit 8, or another separate power electronics outside the pump sump 3.

The inventive method is based on the basic idea that a pump unit requires energy .DELTA.E in order to convey a certain volume .DELTA.V out of the pump sump 3. From this knowledge, a volume flow-specific energy consumption P _Q ( Q ) can be determined, which describes the ratio of the absorbed power P ( Q ) to the flow Q. The volume-flow-specific energy consumption is a measure for the evaluation of the energy efficiency and the maximum utilization of the energy-saving potential. It just describes the power consumption per cubic meter of wastewater pumped: $$\frac{\mathrm{\Delta }e}{\mathrm{\Delta }V}=\frac{\mathrm{\Delta }e/t}{\mathrm{.DELTA.V}/t}=\frac{P\left(Q\right)}{Q}=P_Q\left(Q\right)$$

This volume flow-specific energy consumption P _Q ( Q ) decreases with increasing flow rate Q and then increases again to higher flow rates Q, so that it has a minimum in the range of medium flow rate Q. Operation in this area is the most energy efficient for the pump unit 2. The method now provides to set the pump set just so that this minimum energy is achieved. Two variants are described below to determine this minimum.

The basic procedure of the method according to a first variant is in FIG. 2 illustrated and will be explained below. In this first variant, the optimal flow rate Q _opt is first calculated and then the speed n (Q _opt , h) is calculated, which is required so that the pump unit 2 just conveys the optimal flow rate Q _opt . By means of the second variant, the optimum speed can be calculated directly, ie in one step. FIG. 3 shows a global procedure for both variants, which will be described in more detail below.

The procedure according to FIG. 2 begins with a measurement of the level h in step 20. It should be noted, however, that the measurement of the time-varying current level h (t) is not necessarily required. According to an alternative embodiment, the plant characteristic H _A (Q, h) for the calculation of optimal speed n _opt a constant level h of the container 3 take into account, for example, a mean level h or an upper level limit h _o . In this alternative case, the constant level h = h or h = h _o is set in step 20. Hereinafter, the level is indicated in the equations with h, which hereunder is either the time-variable current level h (t) or one of the above-mentioned constant levels h, h _o to understand.

For the specific combination of Appendix 1 (pump sump 3 together with pressure line 6 and channels 4, 5 and pump unit 2), then first that flow Q _{opt is} sought, in which the specific energy P _Q ( Q ) is minimal, step 22. The combination Plant and pump set 2 is expressed by blocks 30, 32, 34 and 36 which provide the mathematical relationship to determine the volume flow specific energy P _Q ( Q ) for a given flow.

The search for the minimum of the volume flow specific energy P _Q ( Q ) can be made by any mathematical method of the prior art. In the simplest case, Q is varied, ie the specific energy P _Q ( Q ) is calculated for a multiplicity of different delivery flows Q _i between a minimum and a maximum delivery flow, and then the minimum P _{Q, min is} sought from the results obtained, in which case the delivery flow which has just led to this minimum, the sought optimal flow Q _opt .

For this optimum flow rate Q _opt that speed is then n (Q _opt, h) is calculated, which is required so that the pump unit 2 just promotes the optimum flow rate, step 24. This optimum speed n (Q _opt, h) is then on the pump set 2, step 26, or the pump unit 2 is - as far as possible - on this energy-efficient speed n (Q _opt , h) operated.

In addition, exception conditions can be checked in step 28, which can lead to the result that a different speed than the calculated optimum speed n (Q _opt , h) makes sense for the current system state. For example, a state of emergency is that the inlet exceeds the flow rate or a certain maximum level or upper level limit h _o in the pump sump 3 is reached. This can then be a trigger that, instead of the optimum speed n (Q _opt , h), the maximum speed of the pump unit 2 is set to prevent overflow. As part of the "exceptional conditions check" in step 28, one or more conditions are thus checked to identify certain situations and / or operating conditions that may require a speed other _than the optimum speed n (Q _opt , h). However, this test is not required to carry out the invention.

As already noted with regard to blocks 30, 32, 34 and 36, to determine the volume flow stream specific energy consumption P _Q ( Q ), the pump map H _P (Q, n) and the power consumption map P (Q, n) of the pump set 2 to be investigated are determined and at least one plant characteristic H _A (Q, h), the latter also called pipe network characteristic needed.

beschrieben werden kann, das aufgrund der konstanten Drehzahl n = n₀ keine Abhängigkeit von n besitzt. Die Koeffizienten a₀, a₁ und a₂ sind Konstanten.The pump map H _P (Q, n) describes the relationship between the funded by the pump unit 2 flow rate Q at a certain pressure difference Ap between the suction side and the pressure side of the pump 2a, which is expressed in a corresponding delivery height H, at a certain speed n For each particular speed n, there is a pump characteristic H _{P, n} (Q), so that the pump map H _P (Q, n) can also be considered as a plurality of individual pump characteristics H _{P, n} (Q). The graphical representation of this relationship is usually in the so-called HQ diagram. For each speed n, therefore, the pump unit 2 has a certain pump characteristic H _{P, n} (Q), which for the rated speed n _0, for example by means of a polynomial 2nd degree $$H_{P.n_0}\left(Q\right)=a_0+a_{1}Q+a_2{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^2$$

can be described, which has no dependence on n due to the constant speed n = n ₀ . The coefficients a ₀ , a ₁ and a ₂ are constants.

beschrieben werden kann, das aufgrund der konstanten Drehzahl n = n₀ keine Abhängigkeit von n besitzt. Die Koeffizienten b₀, b₁, b₂ und b₃ sind ebenfalls Konstanten.Similarly, the power consumption map P (Q, n) can be set up, which can be considered from a plurality of power characteristics P _n (Q), each for a certain speed n the Describe relationship between the flow rate Q and the power consumption P. For the rated speed n ₀ , the power characteristic P _n0 (Q) can be determined, for example, by means of a 3rd order polynomial $$P_{n_0}\left(Q\right)={\mathrm{<figure-callout\; id="0"\; label="b"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">b</figure-callout>}}_0+{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="imgf0001.png"\; state="\{\{state\}\}">b</figure-callout>}}_{1}Q+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0001.png"\; state="\{\{state\}\}">b</figure-callout>}}_2{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^2+{\mathrm{<figure-callout\; id="3"\; label="b"\; filenames="imgf0001.png"\; state="\{\{state\}\}">b</figure-callout>}}_3{\mathrm{<figure-callout\; id="3"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^3$$

can be described, which has no dependence on n due to the constant speed n = n ₀ . The coefficients b ₀ , b ₁ , b ₂ and b ₃ are also constants.

The pump map H _P (Q, n) and the performance map P (Q, n) are measured by the pump manufacturer for a variety of different speeds, in particular for rated speed n ₀ and provided as measured values or in curve diagrams. Optionally, the pump and performance characteristics are also presented directly by the pump manufacturer in mathematical representation in the manner of a function according to Equation 2 or 3. If this is not done, polynomials according to equations 2 or 3 with the corresponding coefficients for describing the pump characteristic curve or characteristic curve or performance characteristic curve can be determined from the measured values or curve representations by interpolation or approximation according to a manner known per se in the prior art. characteristics are found.

$$H_A\left(Q,,h\right)=d_0-h+d_{1}Q+d_2{Q}^2$$

wobei die Koeffizienten d₀, d₁ und d₂ Konstanten sind und h der Pegelstand (Wasserstand) im Pumpensumpf 3 ist. Das Anlagenkennfeld H_A(Q, h) gemäß GI. 5 reduziert sich im Falle der Verwendung eines konstanten Pegelstands, z.B. h = h_o oder h = h, auf eine Anlagenkennlinie H_A(Q) gemäß GI. 4. Um alle Verfahrensvarianten zu umfassen, wird nachfolgend jedoch stets von einer Anlagenkennlinie H_A(Q, h), obgleich es sich im Falle der Berücksichtigung des veränderlichen aktuellen Pegelstands h(t) eigentlich um ein Kennfeld handelt. d₀ ist der Abstand zwischen dem höchsten Punkt in der angeschlossenen Druckrohrleitung 6 und dem Pumpensumpfboden, sodass sich die geodätische Höhe H_geo durch d ₀ - h gegebenen ist.The same also applies ultimately to the plant map H _A (Q, h), which describes the hydraulic relationship between volume flow Q and head H of the pumping system 1. The plant map H _A (Q, h) is known by the operator of the pumping station due to the proposed dimensioning of inlet and outlet 4, 5 and the pressure line 6; Ultimately, therefore, in order to enable the pump manufacturer to be able to select and offer a suitable pump set. The plant map H _A (Q, h) is usually a parabola with a slope defined by the pipe resistance, which is raised by the geodetic height H _geo , as equations 4 and 5 describe by way of example: $$H_A\left(Q\right)=H_{\mathit{geo}}+{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_{1}Q+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_2{Q}^2$$

$$H_A\left(Q,,H\right)=d_0-H+{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_{1}Q+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_2{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^2$$

where the coefficients d ₀ , d ₁ and d _{2 are} constants and h is the level (water level) in the pump sump 3. The plant map H _A (Q, h) according to GI. In the case of using a constant water level, eg h = h _o or h = h, 5 is reduced to a plant characteristic H _A (Q) according to GI. 4. In order to encompass all variants of the method, however, a plant characteristic curve H _A (Q, h) will always be used below, although in the case of taking account of the variable current level h (t), this is actually a characteristic diagram. d ₀ is the distance between the highest point in the connected pressure pipe 6 and the sump bottom so that the geodetic height H _{geo is given} by d ₀ - h .

For the application of the method according to the invention, it is assumed that at least one system characteristic H _A (Q, h) is known, that is, specified by the manufacturer. In the case of using a constant water level, this is usefully the plant characteristic curve for this constant water level. It is thus no system identification required during operation of the pump set, ie no determination of the system characteristic. Rather, this gives the possibility, even before the commissioning of the pump system 1, in particular in the planning phase, to predict a customer, how high the energy savings by the operation at the optimum speed.

Preferably, the pump map H _P (Q, n) and the power consumption map _P (Q, n) are specified by the manufacturer, so that again no metrological investigations during operation of the pump unit are required.

For the preparation of the mathematical function, which allocates the specific energy consumption P _Q (Q, h), taking into account the system characteristic H _A (Q, h), to a conveying flow Q to be conveyed, the pump characteristics and power consumption characteristics do not become specific only discrete speeds but needed for all speeds. The same is necessary to determine what speed n the pump unit 2 needed to promote a certain flow Q. That is, the entire pump map and power consumption map of the pump set must be known. As already stated, a complete measurement and indication of the respective characteristic map can be carried out as measured values or as polynomials by the pump manufacturer.

$$P_n\left(Q,,n\right)=\frac{{\left(\frac{n}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n}Q\right)}{{\eta }_{\mathit{ges}}\left(n\right)}$$

wobei η_ges einen Gesamtwirkungsgrad beschreibt, der sich aus dem Produkt mehrerer Wirkungsgrade, insbesondere dem Wirkungsgrad des Frequenzumrichters, des Elektromotors 2a und einer etwaigen Kupplung gebildet ist.The pump map H _P (Q, n) and power consumption map P (Q, n) can alternatively be mathematically described, for example, by only the pump characteristic H _{P, n0} (Q) for the rated speed n ₀ and only the power consumption curve P _n0 (Q) are used as the basis for the nominal rotational speed n ₀ and the affinity laws (H ~ n ² , P ~ n ³ ) are used. In this way, for an arbitrary speed n, the corresponding pump characteristic H _{P, n} (Q, n) can be given from equation 6 and the power consumption curve P _n (Q, n) can be given from equation 7, $$H_{P.n}\left(Q,,n\right)={\left(\frac{n}{n_0}\right)}^2{H}_{P.n_0}\left(\frac{n_0}{n}Q\right)$$

$$P_n\left(Q,,n\right)=\frac{{\left(\frac{n}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n}Q\right)}{{\eta }_{\mathit{ges}}\left(n\right)}$$

where η _{ges describes} an overall efficiency, which is formed from the product of several efficiencies, in particular the efficiency of the frequency converter, the electric motor 2a and a possible coupling.

enthalten, wobei der Parameter c eine nicht negative Konstante ist. Dabei bedeutet ein Parameter c = 0, dass der Wirkungsgrad trotz abnehmender Drehzahl n konstant bleibt. Liegen Messwerte für verschiedene Drehzahlen vor, so kann der Parameter c so bestimmt werden, dass das resultierende Kennfeld optimal zu den Messdaten passt. Alternativ können sämtliche Messpunkte interpoliert und so ein Leistungsaufnahmekennfeld generiert werden.The use of the affinity statements thus has the advantage that only a pump characteristic H _{P, n0} (Q) and a power consumption characteristic P _n0 (Q), namely preferably at rated speed n ₀ , need to be known in order to obtain the entire pump characteristic H _P (Q, n ) or power consumption map P (Q, n). To take into account a reduced efficiency with decreasing speed n, the product forming the overall efficiency η _ges can be, for example, a function f _η ( n ) of the shape $$f_{\eta }\left(n\right)=-c\left({\left(\frac{n}{n_0}\right)}^2-\frac{2n}{n_0}+1\right)+1.$$

contain, wherein the parameter c is a non-negative constant. A parameter c = 0 means that the efficiency remains constant despite decreasing speed n. If measured values for different rotational speeds are available, the parameter c can be determined such that the resulting characteristic map optimally matches the measured data. Alternatively, all measuring points can be interpolated and thus a power consumption map can be generated.

For the speed control according to the invention, it should be noted that although theoretically any point in the pump sump 3 can be realized on any system characteristic, in practice pump units in wastewater pumping stations must take into account that the speed should only be regulated within certain limits. ie between a minimum speed value n _min and a maximum speed value n _max . The maximum speed value n _max can be equated, for example, with the rated speed n ₀ . The minimum speed value n _min can be, for example, half the rated speed n ₀ .

If the pump characteristic H _P (Q, n) is selected according to Equation 6 and the pump characteristic H _{P, n0} (Q) at rated speed n ₀ is approximated by a quadratic polynomial according to Equation 2, for each flow Q and a level h (= h (h) t) or h or h _o ) in the pump sump 3, the speed n to be set are calculated from the knowledge that only operating points along the system curve H _A (Q, h) can be set. This means that for these operating points, the equation 6 describing any pump characteristic curve H _{P, n} (Q, n) in the characteristic map yields the same HQ values as the system characteristic curve H _A (Q, h), so equations 5 and 6 are equated and from this the required speed n to be set for delivery of a specific delivery flow Q. can be determined. For the sought speed n just results as a solution of the equation H _{P, n} ( Q, n ) = H _A ( Q, h ) . This results in the following function: $$n\left(Q,,H\right):=\frac{{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">n</figure-callout>}}_0}{2a_0}\left(-a_{1}Q+\sqrt{4a_0\left(d_0-H+{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_{1}Q+\left(d_2-a_2\right){\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^2\right)+a_1^2{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Q</figure-callout>}}^2}\right)\mathrm{,}$$

The power consumption P (Q, n) for an arbitrary flow rate Q and a certain speed n, is calculated according to equation 7. In this equation 7, the general speed n can be replaced by the speed n (Q, h) that is just required to reach a certain flow rate Q at a certain level height h. That is, rotational speed n can be replaced by the right part of equation 9: $$P_n\left(Q.n\left(Q,,H\right)\right)=\frac{{\left(\frac{n\left(Q,,\mathrm{<figure-callout\; id="0"\; label="H\; n"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">H\; </figure-callout>},\right)}{n_{}}\right)}^3{P}_{n_0}\left(\frac{n_0}{n\left(Q,,H\right)}Q\right)}{{\eta }_{\mathit{ges}}\left(n\right)}$$

This gives a mathematical expression for determining the power consumption P, which is no longer dependent on the rotational speed n, but only dependent on the water level h and the flow rate Q. Thus, according to equation 11a, the power consumption P ( Q, h) can be calculated for each level h, while at the same time ensuring that the flow rate Q is on the system curve H _A (Q): $$\tilde{P}\left(Q,,H\right):=P_n\left(Q.n\left(Q,,H\right)\right)$$

The volume flow-specific energy consumption P _Q (Q, h) is then obtained by relating the power consumption P ( Q, h) to the flow rate Q, ie dividing by it: $$P_Q\left(Q,,H\right):=\frac{\tilde{P}\left(Q,,H\right)}{Q}\mathrm{,}$$

FIG. 4 shows a graphical representation of the specific energy consumption in response to the flow rate Q and the level h for an exemplary pump unit 2 and an exemplary plant characteristic. It becomes clear that the specific energy consumption for each water level h has a minimum approximately in the range between 1/3 and 1/2 of the maximum flow rate.

The energetically optimal delivery flow Q _opt is calculated by minimizing the specific energy consumption P _Q (Q, h) above the delivery flow Q for a specific, in particular the measured, level h (t). $$Q_{\mathit{opt}}:=\underset{Q}{\mathrm{argmin}}{P}_Q\left(Q.H\left(t\right)\right)\mathrm{,}$$

That is, the flow rate Q _opt at which the power consumption (P _Q (Q _opt , h)) is minimum is calculated, see step 22 in FIG FIG. 2 , The associated speed n (Q _opt , h), ie, the optimum speed required to deliver the optimum flow Q _opt , is determined by Equation 9a, see step 24 in FIG FIG. 1 , This speed n (Q _opt , h) is then set on the pump unit 2.

The described first variant of the method therefore provides that initially the optimum delivery flow Q _{opt is} determined, preferably according to Equation 13, and subsequently that rotational speed n (Q _opt , h) is calculated, preferably according to Equation 9a, which is set in the pump unit 2 must be, so that it promotes the desired optimum flow Q _opt .

According to the second variant of the method, the optimum speed n _{opt is} calculated directly from the minimization of the volume-flow-specific energy consumption by minimizing it over the speed n. This has the advantage that not only the optimum flow must be calculated. However, this presupposes that the function describing the volume flow-specific energy consumption is not dependent on the flow rate Q. The derivation of a corresponding Calculation rule is reproduced below. Only those aspects of the second variant of the method that are different from the first variant will be explained. Incidentally, the above explanations to the first variant for the second variant also apply.

As explained above for the first variant, all the operating points of the pump unit 2 are located where the current characteristic curve of the pump characteristic field H _P (Q, n) and the system characteristic H _A (Q, h) intersect. This intersection can be described and determined by equating equations 5 and 6. In Equation 9a, the intersection has been resolved to the speed n (Q, h) required to obtain a given flow rate Q at a certain level h. However, the intersection can be resolved even after the flow rate Q (n, h), which results in the setting of a certain speed n at a level h. A specific, sought-after flow Q then results just as a solution of the equation H _{P, n} ( Q, n ) = H _A ( Q, h ) . This results in the following function: $$Q\left(n,,H\right):=\frac{1}{2{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">n</figure-callout>}}_0\left(d_2-a_2\right)}\left(a_{1}n-{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_1{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">n</figure-callout>}}_0+\sqrt{{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">n</figure-callout>}}_0^2\left({\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2+4\left(a_2-{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_2\right)\left(d_0-H\right)\right)-2{\mathit{<figure-callout\; id="0"\; label="nn"\; filenames="imgf0001.png,imgf0005.png"\; state="\{\{state\}\}">nn</figure-callout>}}_0{a}_1{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0001.png"\; state="\{\{state\}\}">d</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="imgf0001.png"\; state="\{\{state\}\}">n</figure-callout>}}^2\left(a_1^2+4a_0\left(d_2-a_2\right)\right)}\right)\mathrm{,}$$

The power consumption P (Q, n) for an arbitrary flow rate Q and a certain speed n, is calculated according to equation 7. In this equation 7, the general flow Q can be replaced by Q (n, h). This is just that flow that sets at a certain level height h and the speed n. That is, the flow rate Q can be replaced by the right part of Equation 9b: $$P_n\left(Q\left(n,,H\right).n\right)=\frac{{\left(\frac{n}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n}Q\left(n,,H\right)\right)}{{\eta }_{\mathit{ges}}\left(n\right)}$$

This gives a mathematical expression for determining the power consumption P _n (Q (n, h), n), which is no longer dependent on the flow rate Q, but only dependent on the water level h and the rotational speed n. Thus, according to equation 11a, the power consumption P (n, h) can be calculated for an arbitrary level h, which results when setting a certain speed n: $$\tilde{P}\left(n,,H\right):=P_n\left(Q,\left(n,,H\right),,n\right)$$

The volume flow-specific energy consumption P _Q (n, h) results, as in the first variant, in that the level-dependent power consumption P ( n, h ) is related to the flow rate Q, ie divided by it. As a level-dependent power consumption but now a mathematical expression is used, which is only dependent on the speed and the level, whereby here again a constant water level can be used: $$P_Q\left(n,,H\right):=\frac{\tilde{P}\left(n,,H\right)}{Q\left(n,,H\right)}\mathrm{,}$$

The energetically optimal rotational speed n _opt is then calculated by minimizing the specific energy consumption P _Q (n, h) over the rotational speed for a specific, in particular the measured water level h (t). $$n_{\mathit{opt}}:=\underset{n}{\mathrm{argmin}}{P}_Q\left(n.H\left(t\right)\right)\mathrm{,}$$

When energy-efficient operation of the variable speed pump unit 2 should be taken to ensure that the optimum flow rate Q _{opt is} not exceeded, since the specific energy consumption increases sharply at lower speeds. As long and as often as possible, the pump unit 2 should be operated at the optimum speed n _opt or n (Q _opt , h). This should be the case, usefully at least when the flow Q _does not exceed the value of the optimal discharge flow rate Q _opt, that less water flows into the pump sump 3 in as is pumped out.

Preferably, the pump characteristic H _P (Q, n), the power consumption map P (Q, n) and the system characteristic H _A (Q, h) in the pump unit 2 associated pump electronics 8 are deposited. The pump set (2) can then automatically calculate and set the optimum speed.

Preferably, the pump unit 2 is operated at operating intervals 10, wherein the calculated optimum speed for an operating interval on the pump unit 2 is set. Such an operating interval 10 is in FIG. 5 to see the curves of the flow rate Q (solid line) and the inlet Q _in (dashed line) shows.

The calculation of the optimal speed n _opt , n (Q _opt , h) can basically be done at any time. However, if the pump set is operated at operating intervals, the determined optimum speed will, of course, only be set at the next operating interval. In particular, however, the calculation can take place both before and during a service interval.

Suitably, the pump unit 2 is turned on when a predetermined upper level limit h _{o is} reached or exceeded, and turned off when a predetermined lower level limit h _{u is} reached or exceeded. This corresponds to a two-point control of the pump unit 2. For the period of this operating interval, the pump unit 2 is ideally operated with the calculated optimum speed n _opt , n (Q _opt , h).

In this exemplary level-dependent activation of the pump set, it becomes clear that the level h generally does not have to enter into the calculation of the optimum speed as a variable. Because if the pump unit is turned on only when reaching the upper level limit h _o , anyway the current level is approximately at this upper level limit h _o , so this always for the calculation of the optimal speed n _opt , n (Q _opt , h _o ) can be used. If the optimum speed n _opt , n (Q _opt , h) is recalculated during an operating interval, the current or average level can be used for the calculation.

The upper level limit h _o may be, for example, between 75% and 85% of a maximum level h _max . The lower level limit h _u may, for example, be the minimum level h _min or between 25% and 35% of the maximum level h _max .

However, it is advantageous if the water level in the sump 3 is kept as high as possible. As a result, the geodetic height H _geo and thus reduces the friction losses. This is achieved by selecting the lower level limit h _u comparatively high, for example between 40% and 60% of the maximum level h _max . In this case, the pump unit 2 is thus operated so that the level h in the pump sump 3 is maintained between 40% and 85%, preferably between 50% and 75%.

If the pump unit 2 is turned on at or after reaching the upper level limit h _o , is pumped until the lower level limit h _{u is} reached. The pump unit 2 is then switched off again and only switched on again when the upper level limit h _{o is} reached. As a result, an operation in the manner of a hysteresis is realized.

FIG. 3 illustrates this method. Analogous to FIG. 2 the level is measured in the pump sump 3 in step 20 and then the optimum speed n _opt , n) (Q _opt , h) as above calculated using one of variants 1 or 2, step 24. Subsequently, the water level h is evaluated. If it reaches or exceeds the upper limit h _o , see step 21, the pump unit 2 is turned on and operated at this calculated speed n _opt , n (Q _opt , h), step 26. The pump sump 3 is thereby increasingly emptied, provided the inlet less than the flow rate. The level h then falls below the upper level limit h _o , so that the condition in step 21 is no longer satisfied. The operation of the pump unit 2 is normally carried out until the water level h has dropped below the lower limit level h _u . This is checked in step 23. If this condition is met, the pump unit 2 is switched off again, step 27.

During the operating interval 10, the pump unit 2 can be operated constantly at the optimum speed. Alternatively, the optimum speed can be recalculated and adjusted again and again during operation in order to take into account the current level h. In that case, the pump set 2 is not operated at a fixed speed. Rather, the operating speed is adjusted to the level 7 in the pump sump 3, that is, the optimal speed n _opt , n (Q _opt , h) set for the respective level 7. This can in particular also take place when the upper limit level h _o already falls below, ie the condition in step 21 is not (more) fulfilled, the lower limit level h _u but not yet reached, ie the condition in step 23 is not reached is. This is in FIG. 3 not shown.

Logically, the two-point control is performed only then, and in particular only as long as the flow Q _in smaller than the calculated optimal flow rate Q _opt, since the level otherwise continues to increase and the pump sump 3 may overflow under certain circumstances.

If the inflow Q _in greater than the current flow Q, instead of the operation of the pump unit 2 with optimal speed n _opt a higher speed than the optimal speed n _opt , n (Q _opt , h) can be set, for example, the maximum speed n _max or Such a speed with which a predetermined level is realized, preferably the upper level limit h _o . Instead of a verification that the flow Q _is greater than the calculated optimal flow rate Q _opt, can be checked whether the water level h in the sump 3 a maximum level h _max reaches or exceeds. This may be the subject of review in step 25 of FIG. 3 be. If this is the case, can be promoted with a higher speed than the optimal speed, for example, with a maximum speed, see step 29. If the inflow Q _in contrast, is not greater than the current flow or the level exceeds the maximum value h _max during an operating interval 10th not, then the procedure is continued at the beginning, step 20.

In the course of operation, the system characteristic curve H _A (Q, h) of the pump system, ie the coefficients d ₀ , d ₁ , d ₂ , can change according to Equation 4 or 5, for example due to deposits that lead to a higher flow resistance. Since the system characteristic H _A (Q, h) for the calculation of the optimal flow rate Q _opt and the optimal speed n _opt , n (Q _opt , h) is mandatory, it can be redetermined during operation, or the coefficients d ₀ , d ₁ , d _{2 are} adjusted.

This can be done on the basis of at least three operating points of the pump unit 2, wherein in particular the flow Q _i for at least three different speeds n _{i is} determined. The flow rate Q can be measured, for example, by means of the volume flow sensor 9. A number of at least three different speeds n _{i are} driven within a certain period of time. This period may include one or more operating intervals 10, preferably three operating intervals 10. This has the advantage that the pump unit 2 in each operating interval 10 with only one rotational speed n, which then can preferably correspond to the inventively calculated optimal speed n _opt , n (Q _opt , h). The period can be, for example, 24 hours.

Ideally, the start-up of different speeds is n _i in intervals, in particular periodically, preferably repeated once per day to the system curve H _A (Q, h) to quasi-continuously monitor and detect a change in the system characteristics (eg, deposits, constipation). Furthermore, it is advantageous if each rotational speed n _i repeats a certain number of times, for example twice in each case, in order to compensate for measurement errors or calculation errors.

Thus, the pump unit 2, for example, six operating intervals 10 are operated at three different speeds n _i , ie in each case an operating interval 10 at a fixed speed n and two operating intervals 10 at the same speed. In order to increase the accuracy of the determination of the system characteristic H _A (Q, h), it is advantageous to use more than three, for example four different speeds. Accordingly, these four rotational speeds n _{i can be run} during eight operating intervals 10.

For each operating interval 10 can each have a flow rate Q̌ and a level ȟ as the average value of the flow rates Q and the water levels h of the corresponding Operating interval 10 can be determined. The level determination can be carried out by measuring the level h by means of sensor 11 and arithmetical averaging. The flow determination can also be done by measuring the flow rate by means of sensor 9 and arithmetical averaging.

Using the pump characteristic map H _P (Q, n), the delivery head Ȟ can then be determined for one of the rotational speeds n _i used, for example according to equation 6. Alternatively, the calculation of the delivery head Ȟ can also be performed using the equation 9a used in equation 6 using the Level ȟ take place. The speed n _i is then not needed.

The system characteristic H _A ( Q, ȟ ) according to Equation 5 or their coefficients d ₁ , d ₂ can then be determined by approximation so that the system characteristic H _A ( Q, ȟ ) optimally to the value triplets ( Q̌ _i , ȟ _i , Ȟ _i ) , i = 1, ..., M · n, for which m times used n speeds fits. In particular, then the distance d ₀ between the pump sump bottom 3 and the geodetically highest point of the pressure line 6 can be determined.

In this way, not only at the beginning of the method but also dynamically during the intended use of the pump unit 2, the mathematical description of the system map H _A ( Q, h ) are always adapted to the current state of the pump system 1. An increased pipeline resistance, for example as a result of deposits in the pressure line 6, can then be considered directly in the energy-efficient control according to the present invention.

On the basis of the current power consumption map P (Q, n), following a redetermination of the current system map H _A ( Q, h ), the specific energy consumption P _Q ( Q, n ) and the energy-optimal rotational speed n _opt , n (Q _opt , h) are calculated. This is preferably carried out between two operating intervals 10 for a certain level h, for example for the upper level limit h _o or for a plurality of different levels h. The calculated speed n _opt , n (Q _opt , h) is then used for the next operating interval 10.

According to an advantageous development of the invention, sliding value triplets ( Q̌ _i , ȟ _i , Ȟ _i ) can be used. This means that, although the number of value triplets remains the same, however, an old value triple ( Q̌ _1, ȟ ₁ , Ȟ ₁ ), in particular the value first determined temporally first, is discarded and a new value triple ( Q̌ _{m · n ,} ȟ _{m · n} , Ȟ _{m · n} ) is added, in particular added at the back. For this purpose, after the end of the operating interval 10, a further averaged over the operating interval 10 flow Q̌ _m . _n and level ȟ _{m · n} and from this the delivery height Ȟ _m . _n be determined. Then, the plant map H _A ( Q, h ) can be updated by adding the already existing values ( Q̌ _i , ȟ _i , Ȟ _i ) , i = 1, ..., ( m · n) -1. Using the new plant map H _A ( Q, h ), a new optimal rotational speed n _opt , n (Q _opt , h) can then be calculated and used for the next operating interval 10. The process then starts all over again.

Starting from the predetermined system characteristic curve H _A (Q, h), the pump system can be monitored by repeatedly determining the system characteristic H _A (Q, h) during operation of the system and the new coefficients d ₀ , d ₁ , d ₂ to be compared with the original coefficients. A deviation, in particular an increasing deviation or a deviation by a certain amount, indicates a deterioration of the plant condition, for example a deposit in the pressure line.

In addition or as an alternative to redetermining the system characteristic curve H _A (Q, h), it is also possible to correct the power consumption characteristic map P (Q, n), ie to redetermine the coefficients b ₀ , b ₁ , b ₂ and b ₃ in equation 3. For this purpose, a number of at least four different operating points is used and in each case the actual rotational speed n _i , the flow rate Q _i and the electrical power consumption P _i determined. The electrical power consumption P _i and the rotational speed n _i can be measured or calculated from electrical variables of the frequency converter. The flow rate Q can also be measured. From these values Q _i , P _i and n _i , the power consumption map P (Q, n) can be newly approximated, preferably by the mathematical methods of the compensation calculation. The more operating points available, the more accurate the approximation. Advantageously, it can then also the Parameter c can be determined from Equation 8. The performance map P (Q, n) is thus better represented and thus also the specific energy calculated more accurately.

Preferably, the redetermination of the system characteristic H _A (Q, h) and / or of the power consumption map P (Q, n) can take place between two operating intervals 10 of the pump unit 2. In this case, operating points from the last operating interval can be used, which have been approached in the context of the regulation or specifically for later redetermination of the plant map H _A (Q, h) and / or the power consumption map P (Q, n).

As an exception, in step 28 after FIG. 2 For example, the following measures may be useful:

If the inlet Q _in the flow Q _opt at optimum speed n _opt , n (Q _opt , h), it is advantageous to adjust the speed just so that the water level h does not increase. This means that the delivery flow Q to be conveyed out of the pump sump 3 must correspond exactly to the inflow Q _in . The speed n (Q = Q _in , h) required for this purpose can be calculated, for example, using Equation 9a by using the feed Q _in for the delivery flow Q.

In order to avoid deposits in the pressure pipe 6 connected to the pump unit 2, the pump unit 2 can preferably be operated at regular intervals, for example every 3 hours, at rated speed n ₀ . This results in that the pressure line 6 and the subsequent sequence 5 are flushed through. Alternatively, such flushing can take place when the recalculation of the plant characteristic field indicates that the pipeline resistance has increased, in particular increased by a certain amount.

Claims (18)

Method for energy-optimal operation of an open pump system (1) for liquid transport, with at least one variable-speed pump unit (2), which conveys the liquid from a container (3), characterized in that depending on at least one factory-set system characteristic curve (H _A (Q, h)) by evaluating a mathematical function (GI 12a, 12b), the flow rate to be delivered (Q) the required volume flow specific energy consumption (P _Q (Q, h), P _Q (n, h)) of the pump unit (2 ), the one speed (n _opt , n (Q _opt , h)) is calculated, at which the volume flow specific energy consumption (P _Q (Q _opt , h), P _Q (n, h)) is minimal, and that the pump unit (2) is operated at this calculated optimum speed (n _opt , n (Q _opt , h)). A method according to claim 1, characterized in that the optimum speed (n _opt ) directly from the minimization of the volume flow specific energy consumption (P _Q (n, h)) is calculated over the speed (n). Method according to claim 1, characterized in that the optimum speed (n (Q _opt , h))) is calculated from the minimization of the volume flow specific energy consumption (P _Q (Q _opt , h)) over the delivery flow (Q), first by the one Flow rate (Q _opt ) is calculated at which the volume flow specific energy consumption (P _Q (Q _opt , h)) is minimal, and then the speed (n (Q _opt , h)) is calculated, which is required to calculate the calculated volume flow (Q _opt ) and that the pump set (2) is operated at this calculated optimum speed (n _opt , n (Q _opt , h). Method according to one of the preceding claims, characterized in that the mathematical function (GI. 12a, 12b) using each a function (GI 5) prescribed by the manufacturer, the pump characteristic diagram (H _P (Q, n)), the power consumption map (P (Q, n)) and at least one system characteristic (H _A (Q, h)) of the pumping station (1) , 6, 7), wherein the pump characteristic map (H _P (Q, n)) is represented by the pump characteristic (H _P, n ₀ (Q)) at rated speed (n ₀ ) and application of an affinity law and the power consumption _map (P (Q, n)) is described by the power consumption characteristic (P _n0 (Q)) at nominal speed (n ₀ ) and application of an affinity law. A method according to claim 4, characterized in that the pump map (H _P (Q, n)) by the equation $$H_{P.n}\left(Q,,n\right)={\left(\frac{n}{n_0}\right)}^2{H}_{P.n_0}\left(\frac{n_0}{n}Q\right)$$

where H _{P, n is} the head, Q is the flow, n is the speed, n _{0 is} the rated speed and H _{P, n0 is} the pump characteristic at rated speed. A method according to claim 4 or 5, characterized in that the pump characteristic (H _{P, n0} (Q)) at rated speed (n ₀ ) by the equation $$H_{P.n_0}\left(Q\right)=a_0+a_{1}Q+a_2{Q}^2$$

where H _{P, n0 is} the head, Q is the _flow and a ₀ , a ₁ and a _{2 are} constants. Method according to one of claims 4 to 6, characterized in that the power consumption map (P (Q, n)) by the equation $$P_n\left(Q,,n\right)=\frac{{\left(\frac{n}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n}Q\right)}{{\eta }_{\mathit{ges}}\left(n\right)}$$

is described, where P _{n is} the power consumption, Q the flow rate, the rotational speed n, n _{0 is} the nominal speed, η _tot overall efficiency and P _n0 are the power consumption characteristic at the rated speed. Method according to one of claims 4 to 7, characterized in that the power consumption characteristic (P _n0 (Q)) at rated speed (n ₀ ) by the equation $$H_{n_0}\left(Q\right)=b_0+b_{1}Q+b_2{Q}^2+b_3{Q}^3$$

where P _{n0 is} the power consumption, Q is the _{flow rate} and b ₀ , b ₁ , b ₂ and b _{3 are} constants. A method according to claim 7 or 8, characterized in that the overall efficiency η _ges a reduction in the efficiency of the pump unit (2) with decreasing speed (n) of the shape $$f_{\eta }\left(n\right)=-c\left({\left(\frac{n}{n_0}\right)}^2-\frac{2n}{n_0}+1\right)+1$$

is taken into account, where f _{η is} a factor which changes as a function of the rotational speed (n), n is the rotational speed, n _{0 is} the nominal rotational speed and c is a non-negative constant. Method according to one of claims 3 to 9, characterized in that the calculation of the optimum speed (n (Q _opt , h)) from the equation of a pump characteristic H _{P, n} (Q, n) of the pump map (H _P (Q, n)) and the system characteristic curve (H _A (Q, h)). Method according to one of claims 3 to 10, characterized in that the optimum speed (n (Q _opt , h)) from the equation $$n\left(Q,,H\right):=\frac{n_0}{2a_0}\left(-a_{1}Q+\sqrt{4a_0\left(d_0-H+d_{1}Q+\left(d_2-a_2\right)Q^2\right)+a_1^2{Q}^2}\right)$$

is calculated, where n the speed, Q is a delivery flow to be reached, in particular the calculated delivery flow (Q _opt ), h a water level, n _{0 is} the rated speed, a ₀ the head H at Q = 0 for rated speed, a _{1 is} a constant volume flow component of the pump characteristic at nominal speed weighting constant a _{2 is} a constant volume quadratic component of the pump characteristic at nominal speed d ₀ the distance between the bottom of the container and the highest point of the pressure line 6, d _{1 is} a constant weighting a linear volume flow component of the system characteristic curve d _{2 is} a constant weighting a quadratic volume flow component of the system characteristic curve. Method according to one of Claims 1 or 3 to 11, characterized in that the mathematical function (GI 12a) for the volume flow-specific energy consumption (P _Q (Q, h)) is given by the equations $$P_Q\left(Q,,H\right):\frac{=P_n\left(Q.n\left(Q,,H\right)\right)}{Q}$$

and $$P_n\left(Q.n\left(Q,,H\right)\right)=\frac{{\left(\frac{n\left(Q,,H\right)}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n\left(Q,,H\right)}Q\right)}{{\eta }_{\mathit{ges}}\left(n\right)}.$$

is formed, where Q is the flow to be reached, h a level, n _{0 is} the rated speed, η _ges an overall efficiency of the pump unit (2) in the pump system (1), n is the speed calculated from the equation of a mathematical function (GI.6) describing a pump characteristic H _{P, n} (Q, n) of the pump characteristic H _P (Q, n) and the system characteristic (H _A (Q, h)) certain flow and level, and P _{n0 is} the power consumption characteristic at rated speed. Method according to one of Claims 1, 2 or 4 to 11, characterized in that the mathematical function (GI 12b) for the volume-flow-specific energy consumption (P _Q (n, h)) is given by the equations $$P_Q\left(n,,H\right):=\frac{P_n\left(Q\left(n,,H\right).n\right)}{Q\left(n,,H\right)}$$

and $$P_n\left(Q\left(n,,H\right).n\right)=\frac{{\left(\frac{n}{n_0}\right)}^3{P}_{n_0}\left(\frac{n_0}{n}Q\left(n,,H\right)\right)}{{\eta }_{\mathit{ges}}\left(n\right)}.$$

is formed, where Q is the flow rate calculated from the equation of a mathematical function (GI. 6) describing a pump characteristic curve H _{P, n} (Q, n) of the pump characteristic diagram H _P (Q, n) and the system characteristic curve (GI water level, h a water level, n _{0 is} the rated speed, η _ges an overall efficiency of the pump unit (2) in the pump system (1), n any speed, and P _{n0 is} the power consumption characteristic at rated speed. A method according to claim 13, characterized in that the flow (Q (n, h)) for a certain speed (n) and a certain level (h) by the equation $$Q\left(n,,H\right):=\frac{1}{2n_0\left(d_2-a_2\right)}\left(a_{1}n-d_1{n}_0+\sqrt{n_0^2\left(d_1^2+4\left(a_2-d_2\right)\left(d_0-H\right)\right)-2{\mathit{nn}}_0{a}_1{d}_1+n^2\left(a_1^2+4a_0\left(d_2-a_2\right)\right)}\right)$$

is given, where n the speed, Q is the flow to be calculated, h a water level, n _{0 is} the rated speed, a ₀ the head H at Q = 0 for rated speed, a _{1 is} a constant volume flow component of the pump characteristic at nominal speed weighting constant a _{2 is} a constant volume quadratic component of the pump characteristic at nominal speed d ₀ the distance between the bottom of the container and the highest point of the pressure line 6, d _{1 is} a constant weighting a linear volume flow component of the system characteristic curve d _{2 is} a constant weighting a quadratic volume flow component of the system characteristic curve. Method according to one of the preceding claims, characterized in that the pump unit (2) in operating intervals (10) with the optimum speed (n _opt , n (Q _opt , h)) is operated, wherein it is turned on when a predetermined upper level limit (h _o ) is reached or exceeded and is switched off when a predetermined lower level limit (h _u ) is reached or fallen _below . Method according to one of the preceding claims, characterized in that the pump unit (2) in operation, the system characteristic (H _A (Q, h)) and / or the power consumption map (P _n (Q, n)) redetermined. Method according to one of the preceding claims, characterized in that the pump characteristic map (H _P (Q, n)), the power consumption map (P (Q, n)) and the system characteristic curve (H _A (Q, h)) in a pump unit ( 2) associated pump electronics (8) are deposited and the pump unit (2) calculates and adjusts the optimum speed automatically. Method according to one of the preceding claims, characterized in that the system characteristic (H _A (Q, h)) takes into account a level (h) of the container (3), said level (h) being the time-variable current level (h (t)) , or is a mean level or an upper level limit (h _o ).

Images