Method and device for controlling energy exchanges between a plurality of energy systems

Abstract

The invention proposes a method for controlling energy exchanges between a plurality of energy systems via a power supply network by means of a control device which is central to the energy systems, wherein at least one of the energy systems comprises a heat generation installation which converts electrical energy from the power supply network into heat. The method is characterized by the following steps: - (S1) providing an electrical load forecast (formula (I)) for the heat generation installation in order to cover an envisaged thermal load (formula (II)); - (S2) transmitting the provided electrical load forecast (formula (I)) to the control device, wherein the other energy systems also transmit respective electrical load forecasts to the control device; - (S3) identifying electrical powers (formula (I)) associated with the energy exchanges by way of the control device based on the transmitted provided electrical load forecasts (formula (I)), wherein the identification is carried out using an optimization method by minimizing an associated target function, and the target function is designed such that the number of starts (formula (III)) of the heat generation installation is minimized in order to cover the envisaged thermal load (formula (II)); and - (S4) controlling the energy exchanges according to the identified electrical powers (formula (I)) by means of the control device. The invention also relates to a control device for carrying out the method.

Description

[0001] Description

[0002] Method and device for controlling energy exchanges between several energy systems

[0003] The invention relates to a method according to the preamble of patent claim 1 and a device according to the preamble of patent claim 10.

[0004] Energy systems, such as urban districts, communities, buildings, industrial facilities, and the like, typically comprise various energy-related systems, such as generation, consumption, and / or storage facilities. The most efficient allocation of the energy generated and consumed in the overall system, as well as the energy exchanges via an associated distribution network (power grid), is a technical challenge that can be solved, for example, by means of a local energy market. The local energy market is technically implemented by a central control device for controlling energy exchanges with respect to the energy systems.

[0005] Such a control device is known, for example, from document EP 3518369 A1.

[0006] However, local energy markets are fundamentally geared towards electrical grids (power grids). Typically, the heat side of energy systems, such as residential buildings, is not explicitly considered. On the other hand, heat accounts for approximately 70 percent of the energy demand of average households. In principle, the demand for electrical energy used to generate heat can also be traded on the local energy market. However, this would mean that the heat generation plants used to generate the heat would be treated like ordinary electrical plants within the local energy market. Specific technical requirements relating to the heat generation plants are not taken into account here. The present invention is based on the object of improving the integration of the provision of heat by a heat generation plant into a local energy market.

[0007] The object is achieved by a method having the features of independent patent claim 1 and by a control device having the features of independent patent claim 10. Advantageous embodiments and further developments of the invention are specified in the dependent patent claims.

[0008] The method according to the invention for controlling energy exchanges between several energy systems via a power grid by means of a control device central to the energy systems, wherein at least one of the energy systems comprises a heat generation system that converts electrical energy from the power grid into heat, is characterized by at least the following steps:

[0009] - Providing an electrical load forecast for the Heat generation plant to cover an intended thermal load.

[0010] - Transmitting the provided electrical load forecast to the control device, wherein the further energy systems also transmit respective electrical load forecasts to the control device;

[0011] - Determination of electrical power associated with energy exchanges (setpoints) by the control device based on the transmitted intended electrical load forecasts, wherein the determination is carried out by a Optimization method is carried out by minimizing an associated objective function, and the objective function is designed in such a way that the number of starts the heat generation plant is minimized to cover the intended thermal load; and

[0012] - Controlling the energy exchanges according to the determined electrical powers using the control device. The method according to the invention and / or one or more functions, features, and / or steps of the method according to the invention and / or one of its embodiments can be computer-aided. In particular, the control device comprises one or more computing units designed and configured, for example by means of commands, to numerically perform the optimization process and determine the electrical power or target powers associated with the energy exchanges.

[0013] From a structural point of view, the IPCC Fifth

[0014] Assessment Report defines an energy system as: “All components related to the generation, transformation, delivery and use of energy” (Annex I, page 1261).

[0015] Energy systems typically comprise multiple components, in particular energy-related systems, for example energy conversion systems, consumption systems, and / or storage systems. Energy systems can generate and / or provide multiple forms of energy (multimodal energy systems). In particular, such an energy system provides one or more forms of energy to a consumer, for example a building or residential building, an industrial facility, or private facilities, with the provision occurring in particular through the conversion of different forms of energy, through the transport of different forms of energy, and / or through stored forms of energy. In other words, the various forms of energy, for example heat, cold, or electrical energy, are coupled by means of the multimodal energy system with regard to their generation, provision, and / or storage.Energy systems include, for example, buildings, particularly residential buildings and / or office buildings and / or industrial facilities.

[0016] As an energy technology plant, the energy system can comprise one or more of the following components: electricity generators, combined heat and power plants, in particular combined heat and power plants, gas boilers, diesel generators, heat pumps, compression chillers, absorption chillers, pumps, district heating networks, energy transfer lines, wind turbines or wind power plants, photovoltaic systems, energy storage systems, in particular battery storage systems, biomass plants, biogas plants, waste incineration plants, industrial plants, conventional power plants and / or the like.

[0017] The present method is therefore based on several energy systems, for example buildings, which exchange energy via a power grid. The energy systems can feed power into and / or out of the power grid at a specific time. Power fed into and / or out of the power grid for a specific period of time results in a specific energy or energy quantity being exchanged between the energy systems, i.e., an energy exchange takes place between the energy systems. At least one of the energy systems comprises a heat generation plant that feeds out electrical energy to provide or cover a heat demand.

[0018] The energy exchanges between the energy systems are controlled by the central control device for the energy systems. The control is carried out by the control device, which is designed to carry out an optimization process. The central control device preferably forms a local energy market.

[0019] An optimization method within the meaning of the present invention is a numerical method in which target values ​​for the powers underlying the energy exchanges are determined. The said powers or power values ​​are variables of a specified objective function that is minimized or maximized as part of the optimization method. By applying an appropriate sign, minimization can always be converted into maximization. In other words, the minimum or maximum of the objective function determines the time-dependent powers or their target values ​​for the control. The objective function typically models a technical goal that is pursued for the energy exchanges, for example the best possible match between production and consumption, the lowest possible carbon dioxide emissions, or the highest possible energy turnover.In this case, the objective function is minimized and is designed to minimize the number of starts of the heat generation plant required to meet the heat demand, possibly using flexibility in heat generation. The term "flexibility" refers to the ability to shift heat generation over time.

[0020] According to a first step of the method according to the invention, an electrical load forecast for the heat generation Electrical load provided by the power generation system to cover an intended thermal load The forecast indicates which electrical power would have to be drawn from the power grid by the heat generation plant at which time in order to cover the time-dependent planned thermal load. With regard to a local

[0021] In the energy market, the electrical load forecast can correspond to a maximum (time-dependent) power that the energy system intends to consume to cover the thermal load. The provision of the electrical load forecast can be determined, for example, by an internal energy system forecast module.

[0022] For example, if the thermal system of a household includes a thermal energy storage unit and a heat generation system, such as a heat pump and / or an electric boiler, which generates heat from electricity and thus couples the domains of electricity and heat, then the electrical energy required for the heat requirement of a household can also be

[0023] Electricity can be optimally procured on the local energy market. For this purpose, the temporal progression of thermal energy demand (thermal load forecast) is determined, and from this, the electrical power requirement (electrical load forecast) for operating the heat generation plant is determined.

[0024] In a second step of the method according to the invention, the provided electrical load forecast is sent to the Control device. The other energy systems can also transmit a respective electrical load forecast to the control device. The central control device thus knows which (maximum) power is to be fed into or fed out of the power grid by each of the energy systems at which times. Further data / information regarding the planned energy exchanges can be received by the control device from the energy systems, in particular information about maximum connected loads, remuneration intentions regarding feed-in and / or feed-out, and / or information about temporally shiftable loads (flexibility). Typically, the aforementioned information, as well as the electrical and thermal load forecasts, relate to a fixed time interval, for example a coming day, in particular the next day.

[0025] According to a third step of the method according to the invention, electrical powers associated with the energy exchanges by the control device based on the transmitted intended electrical load forecasts The determination is carried out using an optimization process by minimizing an associated objective function. The objective function is designed such that the number of starts of the heat generation plant for the de- Coverage of the intended thermal load is minimized becomes.

[0026] The objective function includes the electrical power and the number of starts as variables whose values ​​are determined by minimizing the objective function.

[0027] The objective function can model further technical objectives, for example the lowest possible total carbon dioxide emissions, the highest possible energy conversion and / or the lowest possible total costs.

[0028] By minimizing the start-ups of the heat generation plant according to the invention, the intended heat load is generated as efficiently as possible with regard to wear and tear on the heat generation plant, taking into account flexibility (the ability to shift generation over time). This is the case because typical heat generation plants age, i.e., wear out, with the number of their starts. The present method thus enables optimized operation of the heat generation plants with regard to wear and tear. This makes them easier to integrate into a local energy market, as their specific technical requirements are better taken into account.

[0029] In a fourth step of the present method, the energy exchanges are controlled by the control device according to the determined electrical power. In this case, control is typically carried out indirectly by the control device. The control device has determined setpoints (determined electrical power) for the outputs of each energy system through optimization. These setpoints are then transmitted to the respective energy systems. Within the energy systems, the setpoints for the outputs are implemented by local control units and / or local regulating units, which transmit corresponding control signals to the respective systems, in particular the heat generation system.

[0030] In particular, the present invention has one or more of the following advantages:

[0031] - A more efficient way to place offers / bids for heat generation systems, in particular heat pumps and / or electric boilers, on a local energy market.

[0032] - Exploitation of the flexibility potential of thermal energy systems. - Cost savings for individual energy systems through optimal energy procurement and reduced wear and tear.

[0033] - An opportunity for flexibility marketing and thus an opportunity to develop an additional revenue stream for the energy system. This can be achieved, for example, if the electrical demand of heat generation plants is met at times of increased feed-in through renewable energy generation in the overall system and thus at low prices. The use of flexible heat provision by the heat generation plant, especially if a thermal energy storage system is present, provides a system service (negative control power), which could be rewarded accordingly by the grid operator.

[0034] - Improved resource management of renewable energies by utilizing the shifting potential of thermal energy storage. This can be achieved, for example, if the electrical demand of the thermal system under consideration is met by renewable energy generation at a time of increased feed-in, thus increasing the utilization rate of renewable generation. Alternatively, the heat generation plant could be curtailed due to grid overloads, and the potential heat generation would be lost during this time.

[0035] - An increase in the sustainability of the entire energy system, as the flexibility potential of thermal energy storage is utilized. This avoids additional grid expansion without the additional installation of new storage systems. This can be achieved, for example, if the electrical demand of heat generation plants is met at times of increased feed-in by renewable energy generation in the overall system, thus at low prices. This allows, on the one hand, feed-in peaks to be absorbed. On the other hand, the electrical output of heat generation plants is reduced at times of increased consumption, for example in the morning and / or evening hours, thus avoiding peak loads.The control device according to the invention for controlling energy exchanges between a plurality of energy systems via a power grid, wherein at least one of the energy systems comprises a heat generation system which converts electrical energy from the power grid into heat, is characterized in that the control device is designed and configured to:.

[0036] - an electrical load forecast provided for the heat generation plant to cover a designated thermal load as well as other respective electrical to receive statistical load forecasts from other energy systems;

[0037] - electrical power associated with the energy exchanges based on the submitted planned electrical load forecasts to determine, wherein the determination is carried out by an optimization method by minimizing an associated objective function, and the objective function is designed such that the number of starts the heat generation plant is minimized to cover the intended thermal load; and

[0038] - to control energy exchanges according to the determined electrical power.

[0039] Similar, equivalent and equally effective advantages and / or configurations of the control device according to the invention result from the method according to the invention.

[0040] According to an advantageous embodiment of the invention, the heat generation system is designed as a heat pump.

[0041] Advantageously, this can significantly reduce wear and tear on heat pumps. This is because heat pumps wear out, particularly with the number of times they are started or compressor started. The more often they start up, the greater their wear and tear. However, making the best possible use of the flexibility of heat generation and thus the operation of the heat generation system typically requires the heat generation system to be started and stopped multiple times. In this case, it is therefore possible to provide heat or at least partially cover a heat load while simultaneously reducing wear and tear associated with the temporal flexibility for heat generation provided by the heat pump.

[0042] Alternatively or additionally, the heat generation system can be designed as a water boiler.

[0043] In an advantageous development of the invention, the electrical load forecast from a thermal load forecast according to determined, where COP t the performance factor of the heat pump.

[0044] Advantageously, the heat pump's coefficient of performance is typically known, so that the electrical load forecast can be determined efficiently and with sufficient approximation using the relationship mentioned above. The electrical load forecast can be determined by the energy system itself and / or by the control device.

[0045] According to an advantageous embodiment of the invention, an outside temperature is recorded and the performance factor COP t determined depending on the recorded outside temperature.

[0046] This advantageously allows the dependence of heat supply or heat generation on the outside temperature to be taken into account. This is particularly advantageous for heat pumps that use air as a heat source. Thus, the influence of the heat source can be taken into account.

[0047] In an advantageous development of the invention, the objective function comprises a term of the form to minimize the number of starts, where ξ wear a wear factor and is designed as a binary variable that indicates the number of starts. The objective function can include additional terms that are to be minimized. The optimization procedure then minimizes the entire objective function. The binary variable has a first and second value, preferably the values ​​0 and

[0048] 1, where its typically time-dependent value is determined by minimizing the objective function. Thus, indicates at what time the heat generation system, in particular the heat pump, starts.

[0049] According to an advantageous embodiment of the invention, further binary variables and used in the optimization process, where the operating status of the heat generation plant and the number of stops of the heat generation plant, and the constraints and the optimization process be used.

[0050] This advantageously improves the optimization process. In other words, the starts and stops of the heat generation plant, in particular the heat pump, can be determined using the aforementioned constraints used in the optimization process. The additional binary variables can advantageously be used to determine further technical requirements of the heat generation plant, such as minimum switch-on times and / or minimum switch-off times of the heat generation plant. or used as a constraint in the optimization procedure and thus taken into account.

[0051] In an advantageous development of the invention, the energy system additionally comprises a heat storage unit thermally coupled to the heat generation system, wherein the target function is designed such that storage losses of the heat storage unit are minimized.

[0052] Advantageously, this can minimize storage losses from thermal energy storage. The system consisting of the heat generation plant and thermal energy storage can be be modeled, where the thermal load, the thermal charging capacity of the storage system, the heat output generated by the heat generation plant and which characterizes the thermal discharge capacity of the storage system.

[0053] Furthermore, the thermal energy storage can be The energy content of the storage, Δt a time step, a charging efficiency and η2 a discharging efficiency. The losses of the storage due to self-discharge are modeled by . Model is flexible and offers sufficient

[0054] Accuracy for different storage technologies. Constant parameters, such as the aforementioned efficiencies, can be determined from historical measurement data. The energy content of the storage system can be estimated through further measurements, for example, using existing temperature sensors.

[0055] The losses due to self-discharge are simplified by described, where the loss coefficient φ storage can be estimated using historical measurement data.

[0056] The maximum and minimum storage capacity as well as the maximum charging and discharging capacities can be estimated using system parameters such as maximum and minimum flow and return temperatures and the size of the connecting lines. These limit the corresponding sizes according to These constraints can be used in the optimization lation procedures can be used.

[0057] According to an advantageous embodiment of the invention, the objective function comprises a term of the form for minimizing ization of storage losses, where ξ loss a thermal weighting factor.

[0058] This advantageously allows the memory losses to be considered and minimized during optimization. The objective function therefore preferably includes the term ξ loss • , so that it is minimized. Additional multiplicative numerical constants, such as the time step size of the optimization Δt, can be provided. Furthermore, wear and storage losses are calculated differently by their respective weighting factors ξ wear , ξ loss weighted. Alternatively, or additionally, both terms can be divided by appropriate scaling factors so that they are of the same numerical order. This advantageously improves the numerical analysis.

[0059] The solution to the above-mentioned optimization problem thus includes an optimal trajectory for the power consumption of the heat generation system, in particular the heat pump, for the charge state of the storage, for the storage loading and unloading with the lowest possible wear of the heat generation system.

[0060] In an advantageous development of the invention, the optimization method includes the further constraint used, with a minimum switch-on performance and is the rated output of the heat generation plant.

[0061] This advantageously takes the technical performance limits of the heat generation plant into account during the optimization process. In other words, an optimization result can be determined that respects the technical performance limits of the heat generation plant.

[0062] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawing. The figure schematically shows a flow diagram of a method according to one embodiment of the present invention.

[0063] Elements of the same type, value or function may be provided with the same reference symbols in the figure.

[0064] The present embodiment is based on a building (energy system) that includes a heat pump to at least partially cover its heat requirements. Furthermore, the energy system can include an energy storage device thermally coupled to the heat pump, for example, a water storage tank.

[0065] A thermal load forecast can be determined for the energy system for a future time period. From the determined thermal load forecast, an electrical load forecast for the heat pump can be determined, for example, using its coefficient of performance. The thermal energy storage can be taken into account here. The electrical load forecast thus determined can be obtained through a corresponding offer on a local energy market. The local energy market is formed by a central control device for several energy systems, which controls the energy exchange between the energy systems. To this end, the control device uses a numerical optimization process to determine time-dependent target power levels for each of the energy systems.

[0066] According to a first step S1 of the method, the electrical load forecast for the heat pump is determined to at least partially cover the intended thermal load. This determines which electrical power must be drawn from the power grid at what time in order to cover the corresponding thermal load.

[0067] In a second step S2 of the process, the provided electrical load forecast is transmitted to the control device of the local energy market. All energy systems participating in the local energy market also transmit their electrical load forecasts to the control device. The control device then uses an optimization process to optimally match these with respect to a target function.

[0068] According to a third step S3, the control device determines the electrical power associated with the energy exchanges based on the transmitted, intended electrical load forecasts. The determination is carried out by the optimization method by minimizing an associated target function. The target function is designed or stored in such a way that at least the number of starts of the heat pump required to cover the intended thermal load is minimized. This advantageously reduces wear on the heat pump, while still allowing the temporal flexibility of heat generation by the heat pump, which typically increases the number of starts, to be utilized, and the thermal load can be covered as best as possible.

[0069] Finally, in a fourth step S4 of the process, the electrical power or target power determined by the optimization process are implemented. In other words, the energy exchanges are controlled according to the determined electrical power using the control device. This means that the energy exchanges between the energy systems take place via the power grid.

[0070] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0071] S1 first step

[0072] S2 second step

[0073] S3 third step

[0074] S4 fourth step

Claims

Patent claims 1. A method for controlling energy exchanges between several energy systems via a power grid by means of a control device central to the energy systems, wherein at least one of the energy systems comprises a heat generation system that converts electrical energy from the power grid into heat, characterized by the following steps: - (Sl) Providing an electrical load forecast for the heat generation plant to cover an intended thermal load ; - (S2) transmitting the provided electrical load forecast to the control device, wherein the further Energy systems also transmit respective electrical load forecasts to the control device; - (S3) Determination of electrical power associated with energy exchanges by the control device based on the transmitted intended electrical load forecasts , wherein the determination is carried out by an optimization method by minimizing an associated objective function, and the objective function is designed such that the number of starts the heat generation plant to cover the intended thermal load is minimized; and - (S4) Controlling the energy exchanges according to the determined electrical powers by means of the control device.

2. Method according to claim 1, characterized in that the heat generation system is designed as a heat pump.

3. Method according to claim 2, characterized in that the electrical load forecast from a thermal load forecast according to is determined, whereby COP tthe coefficient of performance of the heat pump.

4. Method according to claim 3, characterized in that an outside temperature is recorded and the performance factor COP t is determined depending on the recorded outside temperature.

5. Method according to one of the preceding claims, characterized in that the objective function has a term of the form to minimize the number of starts where ξ wear a wear factor and is designed as a binary variable that indicates the number of starts.

6. Method according to claim 5, characterized in that further binary variables and used in the optimization process, where the operating status of the heat generation plant and the number of stops of the heat generation plant, and the constraints in the optimization process driving can be used.

7. Method according to one of the preceding claims, characterized in that the energy system additionally comprises a heat storage device thermally coupled to the heat generation system, wherein the target function is designed such that storage losses of the heat storage device are minimized.

8. Method according to claim 7, characterized in that the objective function has a term of the form ξ loss • to minimize storage losses, where ξ loss is a thermal weighting factor.

9. Method according to one of the preceding claims, characterized in that in the optimization method the further constraint is used, whereby a minimum switching power and the rated output of the heat generation plant.

10. Control device for controlling energy exchanges between several energy systems via a power grid, wherein at least one of the energy systems comprises a heat generation plant that converts electrical energy from the power grid into heat. me, characterized in that the control device is designed and configured to: - an electrical load forecast provided for the heat generation plant to cover an intended thermal load to receive and receive further respective electrical load forecasts from the other energy systems; - electrical power associated with the energy exchanges based on the submitted planned electrical load forecasts to determine, wherein the determination is carried out by an optimization method by minimizing an associated objective function, and the objective function is designed such that the number of starts the heat generation plant is minimized to cover the intended thermal load; and - the energy exchanges according to the determined electrical power to control.

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