Method for operating a service provision network, control device for carrying out such a method and service provision network having such a control device

Abstract

The invention relates to a method for operating a service provision network (1) that has at least two service provision devices (3), wherein - a load demand on the service provision network (1) is split over the at least two service provision devices (3) and a virtual service provision device (5) to optimize a cost function, a load distribution being obtained, and wherein - the at least two service provision devices (3) are operated according to the load distribution obtained.

Description

[0001] DESCRIPTION

[0002] Method for operating a power supply network, control device for carrying out such a method and power supply network with such a control device

[0003] The invention relates to a method for operating a power supply network, a control device for carrying out such a method and a power supply network with such a control device.

[0004] Power delivery devices typically physically track the load requirements placed on them.

[0005] In order to achieve a particularly computer-aided load distribution, it would be desirable to be able to mathematically distribute a load requirement on the power provision network between the at least two power provision devices in order to operate a power provision network having at least two power provision devices in such a way that a cost function is optimized.

[0006] However, an optimization problem resulting from the cost function is only mathematically feasible if the sum of the available powers of the at least two power supply devices is at least as large as the load requirement. However, situations are conceivable in which the sum of the available powers of the at least two power supply devices is less than the load requirement. For example, such a situation arises if the load requirement increases by a certain amount, for example 500 kW, within a few seconds and the powers of the at least two power supply devices can only be increased at a smaller rate, for example by 200 kW per minute, for physical or technical reasons. This means that the optimization problem with the constraint of the load requirement is not feasible, and therefore no load distribution can be calculated.The invention is therefore based on the object of providing a method for operating a power supply network, a control device for carrying out such a method and a power supply network with such a control device, wherein the aforementioned disadvantages are at least partially remedied, preferably avoided.

[0007] The object is achieved by providing the present technical teaching, in particular the teaching of the independent claims as well as the embodiments disclosed in the dependent claims and the description.

[0008] The object is achieved in particular by providing a method for operating a power provision network having at least two—in particular physical—power provision devices. A load requirement for the power provision network is distributed among the at least two power provision devices and a virtual power provision device by optimizing a cost function, thereby obtaining a load distribution. Subsequently, the at least two power provision devices are operated according to the obtained load distribution.

[0009] The resulting load distribution assigns a power to each power provision device and a virtual power to the virtual power provision device. Advantageously, the sum of the powers assigned to the at least two power provision devices and the virtual power of the virtual power provision device can always be exactly equal to the load requirement. This allows for optimization of the cost function at any time. The method thus advantageously allows for a particularly computer-aided and thus simple, precise, computerized, and especially automatic load distribution.

[0010] The virtual power is not a real or physically generated power, but rather a purely computational value for solving the optimization problem. In particular, the virtual power assumes a positive value if, at a given time, the sum of the powers assigned to the at least two power-providing devices is less than the load requirement. Alternatively, the virtual power assumes a negative value if, at a given time, the sum of the powers assigned to the at least two power-providing devices is greater than the load requirement.Physically, the power supply network reacts to a fall below the load requirement by the at least two power supply devices in that an electrical frequency of an alternating voltage in the power supply network initially collapses, rises again with an increase in the power assigned to the at least two power supply devices and then reaches a target frequency again when the sum of the powers assigned to the at least two power supply devices is as large as the load requirement.Physically, the power supply network reacts to an exceeding of the load requirement by the at least two power supply devices - in particular in the event of a sudden load drop, wherein the at least two power supply devices cannot be regulated down quickly enough due to their inertia - by an electrical frequency of an alternating voltage in the power supply network initially increasing, falling again with a decrease in the power assigned to the at least two power supply devices and then reaching the target frequency again when the sum of the powers assigned to the at least two power supply devices has fallen to the reduced load requirement.

[0011] In the context of the present technical teaching, a distinction is made between a—in particular physical—power provision device and a virtual power provision device. A particularly physical power provision device is a real device that can provide physically usable power. In contrast, a virtual power provision device is a computational concept that cannot provide physically usable power.

[0012] In one embodiment, the optimization problem for two power delivery devices and one virtual power delivery device is min K(P 1( P2, P V ) = P^ + P2k2+ \P v k v \ under the constraints

[0013] P- + P2+ P v - P Las t 0 < p vwith the cost function K, the assigned powers Pi and P2 of the two power supply devices, the virtual power P v of the virtual power supply device and the predetermined costs or energy prices k of the load requirement PL ast- P l,max and P2,max assigned to the individual power supply devices are the power upper limits assigned to the power supply devices or, in other words, the currently maximum available power. In particular, at least one of these power upper limits is time-dependent, in particular dependent on at least one current physical variable of the assigned power supply device, for example a current boost pressure. In particular, the at least one time-dependent power upper limit Pi,max(t) has a limited rate of change Pi imaxThis means that the available power of at least one power supply device cannot be increased arbitrarily quickly, which in turn results in the problem described above, namely that the sum of the powers Pi, P2 assigned to the power supply devices can be smaller than the load requirement Plast at certain times. Pi.min and P2,mm are the lower power limits assigned to the power supply devices. These can be time-dependent, but also constant over time. In particular, it is possible that at least one of the lower power limits Pi, m in, P2,mm is zero. In particular, it is possible that both lower power limits Pi, m in, P2,mm are zero.

[0014] The method is particularly carried out iteratively. In particular, at least one time-dependent power limit changes over time, so that the load distribution also changes accordingly, in particular until the allocated powers y, P2 total equal the load requirement Pload. In particular, the amount of virtual power P decreases over the course of the iteration cycles due to the specific high costs. vThe power supply network iteratively adjusts to a state in which the assigned powers Pi, P2 total equal the load demand Plast. It is possible for the method to be repeated only when either the load demand Plast or the energy costs fa change. However, it is also possible for the method to be continuously performed iteratively. According to a further development of the invention, the cost function is optimized taking into account at least one additional constraint.

[0015] In one embodiment, the at least one additional constraint takes into account, in particular, a maximum possible power change of the instantaneous power per unit of time of at least one power providing device of the at least two power providing devices.

[0016] In particular, the at least one assigned service a limited rate of change Pt. This means that the power of at least one power supply device cannot be increased arbitrarily quickly, which in turn results in the problem described above that the sum of the powers Pi, P2 assigned to the power supply devices can be smaller at certain times than the load requirement P loads of a preferred embodiment results in a first additional constraint of the form with the minimum power change rate ai associated with the rate of change, mm and associated maximum power change rate ai,max. Alternatively or additionally, a second additional constraint of the form with the minimum power change rate a2,min and the maximum power change rate 2,max assigned to the change rate P2

[0017] If the maximum possible power change per unit of time is taken into account via a constraint, the above-mentioned power upper limits Pi, ma x and P2,max may also be static limits which correspond in particular to the respective rated power of the power supply device.

[0018] According to a further development of the invention, the cost function is calculated based on the energy prices of the at least two power provision devices and predetermined costs of the virtual power provision device. In addition, the predetermined costs of the virtual power provision device are selected to be greater than each of the energy prices of the at least two power provision devices.

[0019] This advantageously ensures that the virtual power supply device is only called upon if the sum of the powers assigned to the at least two power supply devices is less than the load requirement.

[0020] In particular, the predetermined costs of the virtual power supply device are chosen to be at least 1 cent per kWh more expensive than the energy prices of the at least two, in particular physical, power supply devices.

[0021] In one embodiment, the cost function K is preferably additionally calculated based on the maintenance costs for the at least two power provision devices and the virtual maintenance costs of the virtual power provision device. In addition, the virtual maintenance costs of the virtual power provision device are selected to be more expensive than the maintenance costs of the at least two power provision devices. This advantageously allows at least two power provision devices to be operated in a low-wear operating mode.

[0022] In particular, the predetermined costs for the virtual power are selected to be at least 10%, in particular at least 20%, in particular at least 30%, in particular at least 40%, in particular at least 50%, in particular at least 75%, in particular at least 100%, in particular 150%, in particular at least 200%, higher than the energy prices of the at least two, in particular physical, power supply devices in order to ensure a stable and rapid optimization of the cost function K. In particular, the predetermined costs k v for the virtual power based on the energy prices of at least two, in particular physical, power supply devices using the equation k v= f max(fcj) i , where a factor / is predetermined and greater than 1, in particular greater than 1.1, in particular greater than 1.2, in particular greater than 1.3, in particular greater than 1.4, in particular greater than 1.5, in particular greater than 1.75, in particular greater than 2, in particular greater than 2.5, in particular greater than 3. Alternatively or additionally, the virtual maintenance costs are selected to be at least 10%, in particular at least 20%, in particular at least 30%, in particular at least 40%, in particular at least 50%, in particular at least 75%, in particular at least 100%, in particular 150%, in particular at least 200%, greater than the maintenance costs for the at least two power provision devices.

[0023] According to a further development of the invention, the load distribution is determined by minimizing the cost function.

[0024] Advantageously, this makes it possible to operate the service provision network as cost-effectively as possible, taking into account the specific costs of the service provision devices.

[0025] According to a further development of the invention, it is provided that an electric machine which is operatively connected to an internal combustion engine is used as at least one power supply device of the at least two power supply devices.

[0026] According to a further development of the invention, it is provided that an energy storage device is used as at least one power supply device of the at least two, in particular physical, power supply devices.

[0027] In a preferred embodiment, a heat storage device is used as the energy storage device.

[0028] In a further preferred embodiment, a mechanical device selected from a group consisting of a flywheel accumulator, a spring, a pumped accumulator, a compressed air accumulator, and a lifting accumulator is used as the energy storage device. In a further preferred embodiment, an electrical device selected from a group consisting of a battery, an accumulator, and a capacitor is used as the energy storage device.

[0029] In a further preferred embodiment, the electric machine drivingly connected to the internal combustion engine is used as at least one of the at least two power supply devices, wherein, in particular, the electric machine drivingly connected to an internal combustion engine is referred to as a genset. Alternatively or additionally, the energy storage device is used as at least one of the at least two power supply devices.

[0030] In one embodiment, the power supply network has at least one additional power supply device. A photovoltaic system is used, in particular, as the at least one additional power supply device. Alternatively or additionally, a wind turbine is used as the at least one additional power supply device. Alternatively or additionally, a hydropower plant is used as the at least one additional power supply device.

[0031] According to a further development of the invention, a load forecast is specified for a predetermined prediction horizon. Subsequently, the load distribution is determined for a plurality of points in time within the predetermined prediction horizon.

[0032] The object is also achieved by providing a control device, wherein the control device is configured to carry out a method according to the invention or a method according to one or more of the previously described embodiments. The control device is preferably designed as a computing device, particularly preferably as a computer, or as a control unit, in particular as a control unit of a power supply network. In connection with the control device, in particular the advantages arise that were already explained in connection with the method. The control device is preferably configured to be operatively connected to the at least two power supply devices and configured to control them respectively.

[0033] In particular, the virtual power provision device is a computing concept stored or implemented in the control device.

[0034] Finally, the object is also achieved by creating a power provision network with at least two power provision devices and a control device according to the invention or a control device according to one or more of the previously described embodiments. In connection with the power provision network, the advantages already explained in connection with the method and the control device arise in particular.

[0035] The control device is operatively connected to the at least two power supply devices and is configured to control them respectively.

[0036] According to a further development of the invention, at least one of the at least two power supply devices is designed as an electric machine that is drive-connected to an internal combustion engine. Alternatively or additionally, at least one of the at least two power supply devices is designed as an energy storage device.

[0037] The invention is explained in more detail below with reference to the drawings, which show:

[0038] Figure 1 is a schematic representation of an embodiment of a power delivery network, and

[0039] Figure 2 is a flowchart of an embodiment of a method for operating the power delivery network.

[0040] Fig. 1 shows a schematic representation of an embodiment of a power provision network 1. The power provision network 1 has at least two, in particular physical, power provision devices 3, in particular a first power provision device 3.1 and a second power provision device 3.2, a control device 7 and a schematically represented virtual power provision device 5 implemented as a mathematical calculation concept in the control device 7.

[0041] Preferably, at least one power supply device 3 of the at least two power supply devices 3 is an energy storage device 9. Alternatively or additionally, preferably at least one power supply device 3 of the at least two power supply devices 3 is an electric machine 13 drivingly connected to an internal combustion engine 11.

[0042] In one embodiment, the power supply network 1 has at least one additional power supply device 3. In one embodiment, the at least one additional power supply device 3 is a photovoltaic system. Alternatively or additionally, the at least one additional power supply device 3 is a wind turbine. Alternatively or additionally, the at least one additional power supply device 3 is a hydropower plant.

[0043] The control device 7 is operatively connected to the at least two power provision devices 3 and configured to control them, respectively. Furthermore, the control device 7 is configured to perform a method for operating the power provision network 1 and, in doing so, to determine a load distribution for the at least two, in particular physical, power provision devices 3. The method is explained in more detail below with reference to Figure 2.

[0044] Fig. 2 shows a flowchart of an embodiment of a method for operating the power delivery network 1.

[0045] In a first step S1, a load requirement is specified for the power provision network 1. In a second step S2, the specified load requirement is distributed among the at least two power provision devices 3 and one virtual power provision device 5, optimizing a cost function. The cost function is preferably calculated based on the energy prices of the at least two power provision devices 3 and an energy price of the virtual power provision device 5. In this case, the energy price of the virtual power provision device 5 is preferably assumed to be higher than the energy prices of the at least two power provision devices 3. Alternatively or additionally, the cost function is preferably minimized.

[0046] In a third step S3, a load distribution is obtained.

[0047] Subsequently, in a fourth step S4, the at least two power supply devices 3 are operated according to the obtained load distribution.

[0048] In an optional fifth step S5, at least one additional constraint is established, wherein the cost function is optimized in the second step S2 taking into account the at least one additional constraint.

[0049] In an optional sixth step S6, a load forecast for a predetermined prediction horizon is specified, in particular based on the load demand. Subsequently, in the second step S2 and the third step S3, the load distribution is determined for each point in time within the predetermined prediction horizon.

[0050] Preferably, steps S1 to S4, in particular including the fifth step S5 and / or the sixth step S6, are carried out iteratively or cyclically, in particular with a predetermined time interval, in order to determine a load distribution and to operate the power supply network according to the load distribution.

Claims

REQUIREMENTS 1. Method for operating a service provision network (1) comprising at least two service provision devices (3), wherein - a load request to the power supply network (1) is distributed among the at least two power supply devices (3) and one virtual power supply device (5) by optimizing a cost function, thereby obtaining a load distribution, and wherein - the at least two power supply devices (3) are operated according to the obtained load distribution.

2. The method according to claim 1, wherein the cost function is optimized taking into account at least one additional constraint.

3. A method according to any of the preceding claims, wherein the cost function is calculated based on the energy prices of the at least two power provision devices (3) and based on predetermined costs of the virtual power provision device (5), wherein the predetermined costs of the virtual power provision device (5) are assumed to be greater than either of the energy prices of the at least two power provision devices (3).

4. Method according to any of the preceding claims, wherein the load distribution is determined by minimizing the cost function.

5. Method according to one of the preceding claims, wherein at least one of the at least two power supply devices (3) is an electric machine (13) connected to an internal combustion engine (11) for propulsion.

6. Method according to one of the preceding claims, wherein at least one of the power provision devices (3) of the at least two power provision devices (3) is an energy storage device (9).

7. A method according to any one of the preceding claims, wherein a load prediction is specified for a predetermined prediction horizon, and the load distribution is determined for each time point within the predetermined prediction horizon.

8. A control device (7) configured to carry out a method according to any one of the preceding claims.

9. Power provision network (1) comprising a control device (7) according to claim 8 and at least two power provision devices (3) operatively connected to the control device (7).

10. Service delivery network (1) according to claim 9, wherein - at least one of the at least two power supply devices (3) is designed as an electric machine (13) driven by an internal combustion engine (11), and / or wherein - at least one of the at least two power supply devices (3) is designed as an energy storage device (9).

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