Abstract:
The invention relates to a method and to a device for the energy management of a system having a number of components according to an economic market model approach. At least one of the components is characterized by a non-monotonic price-performance relation. By taking into consideration the non-monotonic price-performance relation, a realistic description of the at least one component is provided and thus used to improve energy management of the system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Application No. 10 2012 107 788.6 filed on 23 Aug. 2012, the contents of which are incorporated herein by reference in their entirety. 
       BACKGROUND 
       [0002]    1. Field of Technology 
         [0003]    The invention relates to a method and to a device for the energy management of a system according to an economic market model approach. 
         [0004]    2. Brief Description of Related Art 
         [0005]    The use of a market model approach known from economics for the energy management of systems is known in principle. Thus, a market model approach with price-performance curves for the energy management of, for example, an electrical system in a motor vehicle is known from: Stefan Büchner, “Energiemanagement-Strategien für elektrische Energiebordnetze in Kraftfahrzeugen” Dissertation TU Dresden, 2008, or from: A. Engstle, “Energiemanagement in Hybridfahrzeugen” Dissertation TU Munich, 2008. Moreover, a market model approach for the performance management of distribution networks is known from: Fredrik Ygge, “Market-Oriented Programming and its Application to Power Management” PHD Thesis, Llund University, Sweden, 1998. 
         [0006]    In the known methods for the energy management of a system according to an economic market model approach, price-performance curves (cost functions) are assigned to individual components of the system. For energy sources, these price-performance curves increase monotonically in the prior art, while for energy consumers these price-performance curves decrease monotonically in the prior art. However, in practice, the components of an energy system behave in part in such a way that a realistic description of the components leads to non-monotonic, multivalued price-performance curves. 
       SUMMARY 
       [0007]    The problem of the invention is to provide a method and a device for the energy management of a system according to an economic market model approach which allow a more realistic, improved consideration of properties of components of the system and thus an improved energy management. 
         [0008]    The invention results from the features of the independent claims. Advantageous variants and embodiments are the subject matter of the dependent claims. Additional features, application possibilities and advantages of the invention result from the following description and from the explanation of embodiment examples of the invention that are represented in the figures. 
         [0009]    The method-related aspect of the problem is solved by a method for the energy management of a system according to an economic model approach, wherein the system has a number z of components which comprise at least: one number e of energy sources Q a  and one number f of loads L b , where: aε1, 2, . . . , a1; bε1, 2, . . . , b1; z=a1+b1 and j, tε1, 2, . . . , z. 
         [0010]    The system is preferably an electrical system, in particular an electrical system of a vehicle, a ship, an airplane, or a spacecraft. Alternatively, the system is preferably a thermodynamic system, in particular an air conditioning or heating or cooling system, a mechanical system, a chemical system, or a biological system, or a combination thereof. 
         [0011]    In addition, the z components preferably comprise: settable loads and/or switchable loads and/or settable and switchable loads and/or energy transformers and/or power limiters and/or power splitters and/or power change limiters and/or energy sinks and/or energy lines. 
         [0012]    The method according to the invention comprises the following process steps. 
         [0013]    In a first step, an assignment of an individual price-performance relation PR j  to each one of the z components of the system occurs, relation which assigns prices to performances delivered or received from the given j th  component, wherein each one of the price-performance relations PR j  is represented by a curve in which the performance values l j  delivered or received by the respective j th  component are plotted above price values p j , wherein at least one such price-performance relation PR j=t  is represented by such a non-monotonic curve k t *, and all additional price-performance relations PR j≠t  are represented by such monotonic curves k j≠t . 
         [0014]    The term “price relation” thus comprises particularly assignments of performance values l j  and price values p j  which are not monotonic and multivalued, i.e., which can be represented by a non-monotonic, multivalued curve. The method according to the invention is thus characterized in the first step in that, in contrast to the prior art, at least one component of the system is characterized by such a non-monotonic curve k t *. By taking into consideration such non-monotonic price-performance relations for the characterization of the components of the system, the description of the individual components becomes realistic, and, during the further course of the method, it results in an improved energy management of the system. 
         [0015]    In a second step, an approximation of the non-monotonic curve k t * by a first monotonic approximation curve K n=1,t  occurs, curve which thus represents a first monotonic approximation relation N n=1  (PR j=t ) for the non-monotonic price-performance relation PR j=t . The index n here is an iteration index which starts in the second step at 1 (n=1) and which is increased during the further course of the process in each case by 1. 
         [0016]    The determination of the approximation curve K n=1,t  in the second step occurs, in a particularly preferred variant of the method according to the invention, in such a way that, for all points (l Kn=1,t , p Kn=1,t ) of the approximation curve K n=1,t , it is true that: 
         [0017]    the performance value l Kn=1,t  for a price p Kn=1,t  is greater than or equal to all the performance values l kt*  of the non-monotonic curve k t * at this price p Kn=1,t , and 
         [0018]    the approximation curve K n=1,t  is the curve which, under the above condition, has the smallest difference with respect to the non-monotonic curve k t *. 
         [0019]    Consequently, after the second step, for all the components of the system, monotonic curves or monotonic price-performance relations exist: i.e., besides the curves k j≠t  which are monotonic in any case, the monotonic approximation curve K n=1,t  approximates the non-monotonic curve k t *. Naturally, it is also possible to characterize several components of the system by non-monotonic price-performance relations PR j  or non-monotonic curves k j . 
         [0020]    In a third step, on the basis of the z price-performance relations PR j , wherein the first approximation relation N n=1 (PR j=t ) is used instead of the price-performance relation PR j=t , a determination of a first equilibrium price p n=1  and of an associated equilibrium performance l n=1  for the system occurs. Consequently, for determining the equilibrium performance l n=1  and the equilibrium price p n=1 , monotonic price-performance relations PR or monotonic curves are used exclusively. The determination of an equilibrium price and of an assigned value (here: equilibrium performance) from several price relations/cost curves is known in the prior art, and it is based, for example, on determining, after the summation of all the monotonically increasing curves (or the sum of all the energy source curves) and the subsequent summation of all the monotonically decreasing curves (for example, sum of all the loads), the intersection of the two sum curves. The intersection establishes the equilibrium price and the equilibrium performance. 
         [0021]    In a fourth step, an approximation of the non-monotonic curve k t * by an additional monotonic approximation curve K n+1,t  occurs, the latter curve thus representing an (n+1) th  approximation relation N n+1 (PR j=t ) for the non-monotonic price-performance relation PR j=t . With the fourth step, an iterative improvement of the first monotonic approximation curve K n= 1,t according to a predetermined iteration criterion starts. 
         [0022]    It is preferable for the fourth step to comprise the following substeps. In a first substep of the fourth step, for the last equilibrium performance l n  determined in the method on the basis of the non-monotonic curve k t *, a price value p kt *(l n ) assigned to this equilibrium performance l n  is determined. For the first performance of the fourth step, the equilibrium performance l n=1  is determined beforehand in the third step, so that now the assigned price value p kt *(l n=1 ) can be determined on the basis of the non-monotonic curve k t *. 
         [0023]    In a second substep of the fourth step, the approximation curve K n+1,t  is now determined in such a way that it is true that: 
         [0024]    the approximation curve K n+1,t  comprises the point (l n , p kt *(l n )), 
         [0025]    for all points (l kn+1,t , p Kn+1,t ) of the approximation curve K n+1,t  for which p Kn+1,t &gt;p kt *(l n ), the performance values l Kn+1,t  assigned to the price values p Kn+1,t  are smaller than or equal to the performance values l kt*  of the non-monotonic curve k t *, whose performance values l kt * are greater than l n , 
         [0026]    for all points (l kn+1,t , p Kn+1,t ) of the approximation curve K n+1,t  for which p Kn+1,t &lt;p kt *(l n ), the performance values l Kn+1,t  assigned to the price values p Kn+1,t  are greater than or equal to the performance values l kt * of the non-monotonic curve k t *, and 
         [0027]    the approximation curve K n+1,t  is the curve which, under the above (three) conditions, has the smallest difference with respect to the non-monotonic curve k t *. 
         [0028]    For the case where, for the last determined equilibrium performance l n , a price value p kt *(l n ) assigned to this equilibrium performance l n  cannot be determined on the basis of the non-monotonic curve k t *, for example, because no value for l n  is defined in the non-monotonic curve k t *, the fourth step of the method according to the invention preferably comprises the following substeps. 
         [0029]    In a first substep of the fourth step, the approximation curve K n+1,t  is determined in such a way that it is true that: 
         [0030]    the non-monotonic curve k t * is limited to a curve k tb *, wherein the latter curve is defined in that it contains only the points of the curve k t * whose performance values are either all greater than or all smaller than l n , and 
         [0031]    the determination of the approximation curve K n+1,t  occurs in such a way that, for all points (l Kn+1,t , p Kn+1,t ) of the approximation curve K n+1,t , it is true that: the performance value l Kn+1,t  for a price p Kn+1,t  is greater than or equal to all performance values l ktb * of the non-monotonic curve k tb * at this price p Kn+1,t , and 
         [0032]    the approximation curve K n+1,t  is the curve which, under the above (two) conditions, has the smallest difference with respect to the non-monotonic curve k tb *. 
         [0033]    The preferred variant of the method, indicated here for the second process step, is thus used in the fourth step for determining the approximation curve K n+1,t , wherein, in the present fourth step, the steps of the preferred variant of the second step are applied to the limited curve k tb * instead of the non-monotonic curve k t *, and wherein, in all the subsequent process steps, only k tb * instead of k t * is used. 
         [0034]    In a fifth step of the method according to the invention, on the basis of the z price-performance relations PR j , wherein the approximation relation N n+1 (PR j=t ) is used instead of the price-performance relation PR j=t , a determination of an (n+1) th  equilibrium performance l n+1  and of an associated equilibrium price p n+1  for the system occurs. The determination of the equilibrium performance l n+1  and of the equilibrium price p n+1  occurs, for example, as described above. 
         [0035]    In a sixth step, a repeated run through the fourth and fifth steps takes place for the iterative determination of an approximation relation  N   n+1 (PR j=t ) or of a curve representing said approximation relation, until a predetermined best match criterion is satisfied. 
         [0036]    In a seventh step, a control of individual components or of all the components of the system occurs on the basis of a predetermined energy demand of the loads L b  and of the equilibrium performance  l   n+1  and equilibrium price  p   n+1  determined on the basis of the V. The term “control” is used here in its broad meaning. It includes, for example, regulating/controlling individual components, switching individual components on and off, changing the interconnection of the components in the system, etc. 
         [0037]    The method according to the invention thus allows an energy management of a system according to an economic market model approach, wherein individual components of the system are described by a non-monotonic, multivalued price-performance relation. Typically, the proposed method leads to a rapid convergence, so that an adequate approximation relation  N   n+1 (PR j=t ) can be determined within several operation steps. The embodiments of the invention indicated as preferred variants are in addition reliably robust and they are therefore suitable for the energy management of systems that have to satisfy stringent safety requirements. The method according to the invention here is particularly suitable for the energy management of electrical systems or thermodynamic systems (for example, air conditioning installations) of airplanes, spacecraft or motor vehicles. 
         [0038]    An additional preferred variant of the method according to the invention is characterized in that the individual price-performance relations PR j  of the components are time dependent. Thus, for example, the circumstance of an aging of the component can be taken into consideration in the context of the energy management. 
         [0039]    An additional preferred variant of the method according to the invention is characterized in that the individual price-performance relations PR j  are dependent on a state of the system and/or a state of the respective components. Thus, it is possible to take into consideration, for example, different interconnection states of the components of the system or, for example, state changes of individual components (for example, caused by changed operating temperatures, operating pressures, etc.), which take into consideration a correspondingly changed individual price-performance relations PR j  of the components in question. 
         [0040]    An additional preferred variant of the method according to the invention is characterized in that the individual price-performance relations PR j  are dependent on the components of priorities that are assigned individually in each case, wherein the individual priorities are temporally variable, and the priorities are not identical at any time. 
         [0041]    These priorities define, for example, the importance of a component for the system, and thus, for example, the importance of supplying these components with sufficient energy, or of using a component as energy source. The individual priorities preferably have a hierarchical priority comprising in each case a first priority P1 and a second priority P2. 
         [0042]    If the system has, for example, a number y of switchable loads, then a number y of first priorities P1 y  and a number y of second priorities P2 y  are available for the establishment of the individual priority of the y switchable loads. An initial priority (P1 y  and P2 y ) of each switchable load can be determined, for example, by a detailed load analysis, which takes into consideration the importance of the respective switchable load and the effect of its loss. It is preferable for the first priorities P1 y  to be variable and the second priorities P2 y  to be fixed. Since P1 y  should predominate, P2 y  determines the priority only in situations where P1 is identical for two components (for example, P1 y=3 =P1 y=6 ). The changing priorities of the components can dramatically change the individual price-performance relations PR j  of the affected components, so that taking into consideration the priorities of the components of the system allows a considerably improved energy management. 
         [0043]    The device-related aspect of the problem is solved by a device for the energy management of a system according to an economic market model approach, wherein the system comprises a number z of components which comprise at least: one number e of energy sources Q a  and one number f of loads L b , where: aε1, 2, . . . , a1; bε1, 2, . . . , b1; z=a1+b1 and j, tε1, 2, . . . , z. 
         [0044]    The device according to the invention comprises a first means, by means of which an individual price-performance relation PR j  can be assigned to each one of the z components of the system, relation which assigns prices to the performances delivered or received by the respective j th  component, wherein each one of the price-performance relations PR j  is represented by a curve k j , in which performance values l j  delivered or received by the respective j th  component are plotted above price values p j , wherein at least one such price-performance relations PR j=t  is represented by such a non-monotonic curve k t *, and all additional price-performance relations PR j≠t  are represented by such monotonic curves k j≠t . 
         [0045]    Moreover, the device according to the invention comprises the following means: a second means, which is designed and arranged in order to approximate the non-monotonic curve k t * by a first monotonic approximation curve K n=1,t , which thus represents a first monotonic approximation relation N n=1 (PR j,t ) for the non-monotonic price-performance relation PR j=t ; a third means which is designed and arranged in order to determine, on the basis of the z price-performance relations PR j , wherein the first approximation relation N n=1 (PR j=t ) is used instead of the price-performance relation PR j=t , a first equilibrium price p n=1  and an associated equilibrium performance l n=1  for the system; a fourth means, which is designed and arranged in order to approximate the non-monotonic curve k t * by an additional monotonic approximation curve K n+1,t  which thus represents an (n+1) th  monotonic approximation relation N n+1 (PR j=t ) for the non-monotonic price-performance relation PR j=t ; a fifth means, which is designed and arranged in order to determine on the basis of the z price-performance relations PR j , wherein the approximation relation N n+1 (PR j=t ) is used instead of the price-performance relation PR j=t , an (n+1) th  equilibrium performance l n+1  and an associated equilibrium price p n+1  for the system; a sixth means connected to the fourth and fifth means, which is designed in order to determine iteratively an approximation relation  N   n+1 (PR j=t ) which satisfies a predetermined best match criterion, and a seventh means, which is designed and arranged in order to determine individual components or all the components of the system on the basis of a predetermined energy demand of the loads L b  and of an equilibrium performance  l   n+1  determined on the basis of the equilibrium relation  N   n+1 (PR j=t ), and of the equilibrium price  p   n+1 . 
         [0046]    Preferred variants of the method according to the invention result from a similar application of the explanations made regarding the method according to the invention to the device according to the invention. 
         [0047]    Additional advantages, features and details result from the following description, in which embodiment examples are described in reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]    In the drawings: 
           [0049]      FIGS. 1   a - e  (prior art) show examples of monotonic price-performance relations for a system with three loads and three energy sources; 
           [0050]      FIG. 2  (prior art) shows a representation for explaining the determination of an equilibrium price and of an equilibrium performance for the system with the components of  FIGS. 1   a - e;    
           [0051]      FIG. 3  shows a diagrammatic representation for determining a first monotonic approximation curve K n=1,t    302  with respect to the non-monotonic curve k t *  301 ; 
           [0052]      FIG. 4  shows a diagrammatic representation for determining a second monotonic approximation curve K n=2,t    303  with respect to the non-monotonic curve k t *  301 ; 
           [0053]      FIG. 5  shows an example of an electrical system including two generators (a small and a large generator with corresponding different performance yield and characteristics lines) and a consumer; 
           [0054]      FIG. 6  shows the price-performance relations assigned to the two generators of  FIG. 5 ; 
           [0055]      FIG. 7  shows the performance delivery of the large generator for n=4 iterations of the method according to the invention; 
           [0056]      FIG. 8  shows the performance delivery of the small generator for n=4 iterations of the method according to the invention; 
           [0057]      FIG. 9  shows a diagrammatic process course of a method according to the invention; and 
           [0058]      FIG. 10  shows a diagrammatic structure of a device according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0059]      FIGS. 1   a - e  show examples of monotonic price-performance relations which are represented as performance over price curves, for a system with three loads (load  1 - 3 ) and two energy sources (source  1 - 2 ), as known in the prior art.  FIG. 2  shows a representation for explaining the determination of an equilibrium price and of an equilibrium performance for the system with the components of  FIGS. 1   a - e.  For this purpose, the monotonically decreasing sum curve of the loads  1 - 3  and the monotonically increasing sum curve of the sources  1 - 2  are determined. In  FIG. 2 , these two sum curves are plotted in the price-performance graph. The equilibrium price and the equilibrium performance are obtained from the intersection of the two sum curves. 
         [0060]      FIG. 3  shows a diagrammatic representation for determining a first monotonic approximation curve K n=1,t    302  with respect to a non-monotonic, multivalued curve k t *  301  of a component of the system. Here, the first approximation curve K n=1,t    302  is determined in such a way that for all points (l Kn=1,t , p Kn=1,t ) of the approximation curve K n=1,t    302  it is true that: the performance value l Kn=1,t  for a price p Kn=1,t  is greater than or equal to all the load values l kt * of the non-monotonic curve k t *  301  at this price p Kn=1,t , and the approximation curve K n=1,t    302  is the curve which, under the above condition, has the smallest difference with respect to the non-monotonic curve k t *  301 . 
         [0061]      FIG. 4  shows a diagrammatic representation for determining a second monotonic approximation curve K n+1,t =K n=2,t    303  with respect to the non-monotonic curve k t *  301 . For this purpose, for the last determined equilibrium performance l n=1    304 , a price value p kt *(l n=1 )  305  assigned to this equilibrium performance l n  is determined on the basis of the non-monotonic curve k t *  301 . 
         [0062]    Subsequently, the approximation curve K n=2,t    303  is determined in such a way that it is true that: 
         [0063]    the approximation curve K n=2,t    303  comprises the point (l n=1 , p kt *(l n=1 )), ( 304 ,  305 ), 
         [0064]    for all points (l Kn+2,t , p Kn+2,t ) of the approximation curve K n=2,t    303  for which p Kn+2,t &gt;p kt *(l n=1 ), the performance values l Kn=2,t  assigned to the price values p Kn=2,t  are smaller than or equal to the performance values l kt * of the non-monotonic curve k t *, whose performance values l kt * are greater than l n=1 , 
         [0065]    for all points (l Kn=2,t , p Kn=2,t ) of the approximation curve K n=   2,t    303  for which P Kn=2,t &lt;p kt *(l n=1 ), the performance values l Kn=2,t  assigned to the price values p Kn=2,t  are greater than or equal to the performance values l kt * of the non-monotonic curve k t *, and 
         [0066]    the approximation curve K n=21,t  is the curve which, under the above conditions (the above three bullet points) has the smallest difference with respect to the non-monotonic curve k t *. 
         [0067]      FIG. 5  shows an example of an electrical system including two current generators, a small  501  and a large  502  generator having correspondingly different performance yields and characteristic lines, and a consumer  503 . In this example, the two generators  501  and  502  satisfy the performance demand of a consumer. The first generator  501  is less efficient in comparison to the large generator  502  and it is limited in its performance capacity. The large generator  502  is highly efficient at high performances, but highly inefficient at low performances. This means that the small generator must be used in particular to fill in gaps in the efficiency of the large generator  502  at low performances. 
         [0068]      FIG. 6  shows the price-performance relations assigned to the current generators  501  and  502 . Here, the price-performance relation  601  is assigned to the small current generator  501 , and the price-performance relation  602  is assigned to the large current generator. As one can easily see, the price-performance relation  602  is represented by a non-monotonic curve. 
         [0069]    The method according to the invention is now applied to this example system. Here, the number of the equilibrium prices/equilibrium performances (including negotiation rounds) is limited to four in the current market model. In other words, the market model comprises four parallel market models, which are valid in each case in one of the negotiation rounds. The term “negotiation round” is used here as a synonym for determining an equilibrium price-equilibrium performance in a market model. 
         [0070]    It is assumed here that the performance demand increases at a constant rate. By using the method, one gets the performance deliveries of the generators  501 ,  502 , which are represented in  FIG. 6  and  FIG. 7 . Here,  FIG. 7  shows the performance delivery of the large generator  502  for in each case the four negotiation rounds of the method according to the invention (MAX(n)=4), and  FIG. 8  shows the performance delivery of the small generator  501  for the respective four negotiation rounds of the method according to the invention. 
         [0071]    After the first negotiation round, one gets the curves  701  or  801  in  FIG. 7  or  FIG. 8 . After the second negotiation round, one gets the curves  702  or  802 . After the third negotiation round, one gets the curves  703  or  803 . After the fourth negotiation round, one gets the curves  704  or  804 . 
         [0072]    After the first negotiation round (n=1), the large generator  502  is actuated in such a way that it displaces the small generator  501 . Starting with the second negotiation round (n=2), in the lower performance range, the small generator  501  is also used. After the fourth treatment round (n=4), the result shows a nearly discrete switching off of the small generator  501  and the simultaneous switching on of the large generator  502 , as soon as the large generator  502  is more efficient than the small generator  501 . 
         [0073]      FIG. 9  shows a diagrammatic course diagram of a method according to the invention for the energy management of a system according to an economic market model approach, wherein the system comprises a number z of components which comprise at least: one number e of energy sources Q a  and one number f of loads L b , where: aε1, 2, . . . , a1; bε1, 2, . . . , b1; z=a1+b1 and j, tε1, 2, . . . , z. The method according to the invention comprises the following steps. In a step  901 , an assignment of an individual price-performance relation PR j  to each one of the z components of the system occurs, relation which assigns prices to the performances delivered or received by the respective j th  component, wherein each one of the price-performance relations PR j  is represented by a curve k j , in which performance values l j  delivered or received by the respective j th  component are plotted above price values p j , wherein at least one such price-performance relation PR j=t  is represented by such a non-monotonic curve k t *, and all additional price-performance relations PR j≠t  are represented by such monotonic curves k j≠t . In a step  902 , an approximation of the non-monotonic curve k t * by a first monotonic approximation curve K n=1,t  occurs, which thus represents a first monotonic approximation relation N n=1 (PR j=t ) for the non-monotonic price-performance relation PR j=t . In a step  903 , on the basis of the z price-performance relations PR j , wherein the first approximation relation N n=1 (PR j=t ) is used instead of the price-performance relation PR j=t , a determination of a first equilibrium price p n=1  and of an associated equilibrium performance l n=1  for the system occurs. In a step  904 , an approximation of the non-monotonic curve k t * by an additional monotonic approximation curve K n+1,t  occurs, which thus represents an (n+1) th  monotonic approximation relation N n+1 (PR j=t ) for the non-monotonic price-performance relation PR j=t . In each step  905 , on the basis of the z price-performance relations PR j , wherein the approximation relation N n+1 (PR j=t ) is used instead of the price-performance relation PR j=t , a determination of an (n+1) th  equilibrium performance l n+1  and of an associated equilibrium price p n+1  for the system occurs. In a step  906 , a repetition of steps  904  and  905  occurs for the iterative determination of an approximation relation  N   n+1 (PR j=t ), which satisfies a predetermined best match criterion. In a step  907 , a control of individual components or of all the components of the system occurs, on the basis of a predetermined energy demand of the loads L b , and of the equilibrium performance  i   n+1 , determined on the basis of the approximation relation  N   n+1 (PR j=t ), and of the equilibrium price  p   n+1 . 
         [0074]      FIG. 10  shows a diagrammatic structure of a device according to the invention for the energy management of a system according to an economic market model approach, and for carrying out a method according to the invention according to one of the previous claims  1 - 9 , wherein the system comprises a number z of components which comprise at least: one number e of energy sources Q a  and one number f of loads L b , where: aε1, 2, . . . , a1; bε1, 2, . . . , b1; z=a1+b1 and j, tε1, 2, . . . , z; comprising: a first means  1001 , by means of which it is possible to assign to each one of the z components of the system an individual price-performance relation PR j  which assigns prices to performances delivered or received by the respective j th  component, wherein each one of the price-performance relations PR j  is represented by a curve k j , in which performance values l j  delivered or received by the respective j th  component are plotted above price values p j , wherein at least one such price-performance relation PR j=t  is represented by such a non-monotonic curve k t *, and all additional price-performance relations PR j≠t  are represented by such monotonic curves k j≠t , a second means  1002 , which is designed and arranged in order to approximate the non-monotonic curve k t * by a first monotonic approximation curve K n=1,t  which thus represents a first monotonic approximation relation N n=1 (PR j=t ) for the non-monotonic price-performance relation PR j=t , a third means  1003 , which is designed and arranged in order to determine, on the basis of the z price-performance relations PR j , wherein the first approximation relation N n=1 (PR j=t ) is used instead of the price-performance relation PR j=t , a first equilibrium price p n=1  and an associated equilibrium performance l n=1  for the system, a fourth means  1004 , which is designed and arranged in order to approximate the non-monotonic curve k t * by an additional monotonic approximation curve K n+1,t  which thus represents an (n+1) th  monotonic approximation relation N n+1 (PR j=t ) for the non-monotonic price-performance relation PR j=t , a fifth means  1005 , which is designed and arranged in order to determine, on the basis of the z price-performance relations PR j , wherein the approximation relation N n+1 (PR j=t ) is used instead of the price performance relation PR j=t , an (n+1) th  equilibrium performance l n+1  and an assigned equilibrium price p n+1  for the system, a sixth means  1006  which is connected to the fourth ( 1004 ) and fifth ( 1005 ) means, designed in order to determine iteratively an approximation relation  N   n+1 (PR j=t ) which satisfies a predetermined best match criterion, and a seventh means  1007 , which is designed and arranged in order to control individual components or all the components of the system on the basis of a predetermined energy demand of the loads L b , and of an equilibrium performance l n+1 , determined on the basis of the approximation relation  N   n+1 (PR j=t ), and of the equilibrium price  p   n+1 . 
         [0075]    Although the invention has been explained and illustrated in further detail using preferred embodiment examples, the invention is not limited to the disclosed examples, and the person skilled in the art can derive other variations therefrom without going beyond the scope of protection of the invention. Therefore, it is clear that a plurality of variation possibilities exist. It is also clear that the embodiments mentioned as examples really represent only examples that in no way can be interpreted as limiting, for example, the scope of protection, the application possibilities, or the configuration of the invention. Rather, the present description and the description of the figures make it possible for the person skilled in the art to effectively implement the embodiments given as examples, where the person skilled in the art, in the knowledge of the disclosed inventive idea, can make numerous changes, for example, with regard to the function or the arrangement of individual elements mentioned in an embodiment example, without leaving the scope of protection which is defined by the claims and their legal equivalents, such as further explanations provided in the description.