Method and system for charging an electric vehicle on a local energy network
Patent Information
- Application Number
- EP2023797781
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-21
- Filing Date
- 2023-10-26
- Publication Date
- 2025-10-01
AI Technical Summary
Existing systems for charging electric vehicles on local energy networks face inefficiencies due to suboptimal utilization of stationary storage and energy generation systems under zero-load control, particularly when surpluses cannot be fed into the public energy distribution network, and communication barriers between charging points and energy systems.
A method that monitors bidirectional electrical power flow and gradually increases charging power at the charging point to maximize system performance of stationary storage and energy generation systems without requiring knowledge of their state or communication, ensuring complete utilization and preventing feed into the energy distribution network.
This approach allows for nearly complete utilization of stationary storage and energy generation systems, enabling faster charging of electric vehicles while avoiding feed into the public network, even when communication protocols differ, and ensures compliance with regulations prohibiting surplus feeding.
Smart Images
Figure 1.1
Abstract
Description
[0001] METHOD AND SYSTEM FOR CHARGING AN ELECTRIC VEHICLE FROM A LOCAL ENERGY GRID
[0002] The invention relates to a method for charging a drive battery of at least one electric vehicle at at least one charging point of a property with a local energy grid that is connected to an energy distribution grid via a grid connection point and to which a plurality of unregulated consumers as well as the at least one charging point, at least one stationary storage device and at least one energy generation plant are connected. In the method, electrical power flowing via the grid connection point is monitored bidirectionally and the stationary storage device and the at least one energy generation plant are operated by means of zero-load control at the grid connection point. The invention also relates to a system with a property and an electric vehicle, wherein the electric vehicle can be connected to a charging point of the property to charge its drive battery and wherein the system is configured to carry out the method.The invention is particularly advantageously applicable to charging an electric vehicle on a home network.
[0003] The most sustainable form of electromobility is the generation of home-generated electricity from energy generation systems such as PV systems and wind turbines, and its storage in an electric vehicle's traction battery. The system can also be supported by a stationary energy storage system or "stationary storage" to bridge interruptions in energy generation, temporarily increase the available electrical power, and / or bridge a loss of connection to the electric vehicle during energy generation. To fully utilize the generation from a home-generated energy system to charge the electric vehicle, the principle of zero-load control is often used at the grid connection point between a local household energy grid and a public energy distribution grid. Zero-load control measures the electricity consumption and feed-in at all phases at the grid connection point.The goal of zero-load control is to balance consumption and feed-in, meaning that electricity is neither drawn from the public energy distribution grid nor fed into the public energy distribution grid. Stationary storage systems, in particular, also operate according to the zero-load control principle. If surpluses are generated in the household energy grid, they are first temporarily stored in the stationary storage system until it can no longer absorb any more energy. If the energy generation system can no longer fully cover the energy demand in the household energy grid, power is drawn from the stationary storage system. The charging or discharging power of the stationary storage system is geared towards balancing the power balance at the grid connection point, which corresponds to zero.
[0004] In a home energy network connected to a power generation system, a stationary storage unit, and a charging station, using the stationary storage unit based on zero-load control is problematic in this context, as the stationary storage unit only provides power when electricity needs to be drawn from the grid. Therefore, the stationary storage unit is not always optimally utilized.
[0005] In some countries or with some grid operators, surplus power from a home's own power generation system may not be fed into the public energy distribution grid. In these countries, the zero-load control of the power generation system's inverter is a prerequisite for the system's operation. Since the inverter regulates itself down independently, the maximum generation capacity of the power generation system and its surplus cannot be easily determined by measuring the grid connection point.
[0006] DE 20 2012 101 240 U1 discloses an energy management system for measuring and controlling the flow of electricity between a public AC grid and a stand-alone unit, comprising the following features: at least one power generation unit, in particular for generating electricity from a renewable energy source, power consumers, a storage device, and means for controlling the flow of electricity between the power generation unit, the consumers, the storage device, and the AC grid, wherein the means for controlling the flow of electricity comprise at least one energy management unit connected between the power generation unit and the storage device and connecting them to the consumers and the AC grid, as well as a bidirectional power meter connected between the stand-alone unit and the AC grid for measuring the power exchanged between the stand-alone unit and the AC grid.and a control device for controlling the energy management unit based on the power measured by the bidirectional power meter, which control device is designed to minimize the power measured by the bidirectional power meter by simultaneously controlling the power flow between the power generation unit and the storage, the loads, and the AC grid.
[0007] DE 20 2014 001 367 U1 discloses automatic power control of a charging device for electric vehicles depending on the power of a self-generating system (adaptive charging control) - zero-sum control at the grid transfer.
[0008] It is the object of the present invention to at least partially overcome the disadvantages of the prior art and, in particular, to provide a possibility with little effort to particularly effectively utilize an energy generation plant and a stationary storage system of a local energy network of a property for charging an electric vehicle on the basis of a zero-load control.
[0009] This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.
[0010] The object is achieved by a method for charging a drive battery of at least one electric vehicle at at least one charging point of a property with a local energy network, which is connected to an energy distribution network via a network connection point and to which several unregulated consumers as well as the at least one charging point, at least one stationary storage device and at least one energy generation plant are connected, wherein the at least one charging point is designed to specify a charging power for charging the drive battery of this electric vehicle after connection of a respective electric vehicle, and wherein in the method
[0011] - electrical power flowing through the grid connection point is monitored bidirectionally,
[0012] - at least one stationary storage unit is operated by means of a zero-load control at the grid connection point and
[0013] - the at least one charging point gradually increases the charging power after the electric vehicle is connected until the at least one stationary storage unit and the at least one energy generation plant achieve their maximum system power,
[0014] - whereby the (increase) steps are chosen to be large enough that the stationary storage system attempts (e.g., is regulated or regulates itself) to provide or compensate for the associated increased demand for system power. This method has the advantage of enabling the stationary storage system and the energy generation system to be practically fully utilized by gradually increasing system power, without the charging point needing to know the charge level and power levels of the stationary storage system and / or the energy generation system, etc. This advantageously eliminates the need for communication between the charging point and the energy generation system and / or the stationary storage system. This is particularly advantageous if the charging point, energy generation system, and / or stationary storage system do not use the same communication protocol and / or interfaces, e.g., because they belong to different "manufacturer worlds."Another advantage is that the process does not generate any feed-in to the energy distribution grid. Furthermore, the combination of stationary storage and a power generation system enables faster charging of the electric vehicle than charging exclusively from surplus energy from the power generation system.
[0015] The electric vehicle can be a hybrid vehicle, e.g., a plug-in hybrid vehicle (PHEV), or a fully electric or battery-powered vehicle (BEV). The electric vehicle can be a passenger car, bus, truck, motorcycle, etc.
[0016] The electric vehicle can be designed for unidirectional charging of its drive battery. The electric vehicle can be designed for bidirectional charging, i.e., charging and discharging, of its drive battery.
[0017] The local energy grid serves to distribute energy within a property. It can also be referred to as a "local grid," "microgrid," or, in the case of residential buildings, a "home grid." The energy distribution grid is, in particular, a public energy distribution grid.
[0018] In this case, energy and power are understood to mean electrical energy and electrical power respectively.
[0019] An "unregulated" consumer is defined in particular as an electrical consumer or load whose power consumption cannot be regulated with respect to zero-load control at the grid connection point. This includes, for example, end consumers such as household appliances (stoves, washing machines, dishwashers, toasters, etc.), media devices (televisions, etc.), instantaneous water heaters, lamps, air conditioners, etc.
[0020] The fact that the at least one charging point is designed to specify a charging power for charging the drive battery of an electric vehicle after it has been connected to the vehicle includes, in particular, that the charging point is equipped with a corresponding control system.
[0021] The monitoring of electrical power via the grid connection point is bidirectional, meaning that a distinction can be made between energy consumption from the energy distribution grid and energy feed-in to the energy distribution grid. Monitoring can be performed, for example, via an intelligent electricity meter (so-called "smart meter") or – if no smart meter is available or the smart meter operator does not share its measurement data with the property operator – via an energy meter installed topologically serially to the grid connection point. The measurement data from the power (balance) is shared with at least one energy generation plant and / or with at least one stationary storage unit for zero-load control. The charging point also receives this measurement data.
[0022] The stationary storage system absorbs energy when there is a surplus in the local energy grid until it is fully charged. If excess power cannot be absorbed by the stationary storage system (e.g., because it is fully charged) and feeding energy into the electricity distribution grid is to be avoided, the power generation system, particularly its inverter, regulates the energy feed-in to the local energy grid.
[0023] In particular, if the at least one stationary storage device is not fully charged, the energy generated by the at least one energy generation system is used to charge the electric vehicle and not to charge the stationary storage device, which can advantageously shorten a charging process.
[0024] The fact that the at least one stationary storage facility and the at least one energy generation plant deliver their maximum system output means, in particular, that they deliver or output the maximum combined electrical output. The "system output" can therefore correspond, in particular, to the combined electrical output of the at least one stationary storage facility and the at least one energy generation plant.
[0025] It is a further development that at least one power generation plant provides its maximum generation capacity. This is particularly advantageous when feeding electricity from the local power grid into the energy distribution grid is permitted. This eliminates the sometimes necessary requirement to reduce the output power of at least one power generation plant.
[0026] A further development is that at least one power generation plant provides its maximum permitted generation capacity, i.e., the maximum generation capacity that is or can be delivered by the power generation plant without feeding electricity from the local energy grid into the energy distribution grid. This is particularly advantageous if feeding electricity from the local energy grid into the energy distribution grid is prohibited, for example, by law or contract.
[0027] The fact that the (increase) steps are selected to be large enough that the stationary storage system attempts to compensate for the corresponding increase in system power demand means, in particular, that a step-related deviation from zero load at the grid connection point not only lies within small fluctuation ranges, which does not result in a targeted increase in the electrical power supplied by the stationary storage system, but is so large that the stationary storage system attempts to increase its currently supplied electrical power in response to the increased demand caused by the step-by-step increase. If the stationary storage system can compensate for the corresponding increase in system power demand, it increases its supplied electrical power; otherwise, it does not.
[0028] One embodiment provides that the charging power is adapted to the (currently maximum) system power that can be delivered during the charging process. This includes, for example, reducing the charging power after a maximum value has been reached if less system power can be provided, for example if the at least one energy generation plant and the at least one stationary storage unit can no longer provide as much electrical power. The same applies if unregulated consumers are switched on and off. The charging power is set, in particular regulated, in such a way that the power at the grid connection point is just above, but far enough above zero watts (consumption) that the stationary storage unit regulates against it, as far as it is able to do so. In particular, the traction battery is only charged with the last gradually adjusted charging power until the power consumption from the energy distribution grid exceeds a predetermined amount.In this case, for example, the charging power can be reduced again until a lower amount of power consumption from the energy distribution network is reached.
[0029] The fact that the charging point gradually increases the charging power can be implemented in one embodiment in such a way that the charging point increases the charging power of the electric vehicle, in particular regulates it, so that a grid connection with a certain or predetermined step size is established at the grid connection point, e.g. of 100 W. Due to the deviation from the zero load at the grid connection point thus generated, the energy generation plant and / or the stationary storage system increase their energy feed into the local energy grid by the same amount, e.g. of 100 W, until a zero load is present at the grid connection point again, if possible, i.e. if the energy generation plant can further increase its energy feed-in or the stationary storage system is not completely discharged. When a zero load is present at the grid connection point again, the charging point increases the charging power again so that a grid connection with a certain step size is established, e.g. again of 100 W.The energy generation plant and / or the stationary storage unit then increase their energy feed into the local energy grid by the same amount, e.g. 100 W, until there is no load at the grid connection point again, if possible. This interplay is repeated until the at least one stationary storage unit and the at least one energy generation plant deliver maximum system power and can therefore no longer compensate for the power consumption at the grid connection point increased by the charging point or can no longer reduce it to zero. Once this state is reached, the traction battery is charged with the last set charging power, i.e. with a typically low power consumption from the energy distribution grid, but maximum power provision by the at least one energy generation plant and the at least one stationary storage unit, as long as the grid consumption at the grid connection point remains within the specified range, e.g. 100 W.The fact that the charging point gradually increases the charging power can be implemented in another embodiment in such a way that the charging point increases the charging power for charging the drive battery in a predetermined increment. This embodiment is particularly easy to implement because it is not the consumption at the grid connection point that is set to a specific font size, but only the charging power. The charging power can be increased by 100 W, for example. Due to fluctuations in consumption in the local energy grid and / or in the energy feed-in by the energy supply facility (e.g. due to changing cloud cover), it may happen that the grid connection point slightly reduces the amount of power drawn from the energy distribution grid. Nevertheless, the interplay described above between increasing the charging power and balancing the resulting consumption through zero-load control remains fundamentally the same.
[0030] The size of the increase steps is generally not limited. The larger the steps, the faster the charging power is reached at which the at least one stationary storage unit and the at least one energy generation system provide maximum power. A disadvantage is that upon reaching this state, the grid draw is greater than with smaller steps. A particularly advantageous compromise between increasing the charging power and grid draw has been found for the gradual increase to include an increase in steps between 50 W and 200 W, in particular of approximately 100 W.
[0031] Furthermore, a particularly advantageous embodiment includes the stepwise increase in steps between 0.5% and 2%, in particular approximately 1%, of a maximum charging power. For example, if the electric vehicle can be charged at this charging point with a maximum power of 11 kW, steps between 55 W and 220 W would be particularly advantageous, in particular approximately 110 W.
[0032] It's a development that the step size is kept constant. It's a development that the step size is adjustable.
[0033] It is a design that prevents the targeted feed-back of energy generated by at least one power generation system into the energy distribution grid. This corresponds to the case in some countries or with some grid operators, where surpluses from the property's own power generation system are not fed into the public energy distribution grid. To comply with this operating condition, the feed-in of energy generated by the power generation system into the local energy grid can be reduced, for example, in the case of a photovoltaic system, by reducing the inverter's power.
[0034] The at least one energy generation system comprises at least one renewable energy generation system. In one embodiment, the at least one energy generation system comprises at least one photovoltaic system, at least one wind turbine, a power-generating wood-fired system, and / or a geothermal system, etc.
[0035] In one embodiment, at least one energy generation plant is connected to the local energy grid via an inverter, and the inverter is controlled so that it varies the energy fed into the local energy grid by the energy generation plant for zero-load control. In other words, if an unauthorized feed-in of surplus energy into the energy distribution grid is imminent or occurs, the energy generation plant can control its inverter so that a zero load is maintained or achieved again at the grid connection point. This can happen, for example, if the surplus cannot be temporarily stored by the stationary storage system, e.g. because it is fully charged. If there is a subsequent threat of grid consumption, the energy fed into the local energy grid by the energy generation plant can be increased again.
[0036] One configuration is that the property is a residential building, particularly a single-family home. This advantageously serves the spread of electromobility. However, the property can also, in principle, be a commercial property, e.g., an office building, a small business, etc.
[0037] One embodiment involves a wallbox as the charging point. A further development involves a parking space that is inductively coupled to the electric vehicle.
[0038] The object is also achieved by a system comprising a property and an electric vehicle, wherein the electric vehicle can be connected to a charging point of the property to charge its drive battery and wherein the system is configured to carry out the method as described above.
[0039] The system can be designed analogously to the process and has the same advantages.
[0040] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following schematic description of an embodiment, which is explained in more detail in connection with the drawings.
[0041] Fig.1 shows a system with a property and an electric vehicle;
[0042] Fig.2 shows a curve of a charging power for charging a drive battery of the electric vehicle from Fig.1 by means of a possible variant of the method according to the invention.
[0043] Fig.1 shows a system HOME, EV with a property, e.g. in the form of a single-family house, HOME and an electric vehicle EV.
[0044] The single-family home HOME has a local energy grid (LOG) connected to the public energy distribution grid (EVN) via a grid connection point (NCP). A smart meter (SM) is located at the grid connection point (NCP), which can measure the current flow, or the power currently flowing through the grid connection point (NCP), in both directions. Connected to the local energy grid (LOC) are a charging point (EVSE), e.g., a wallbox for connecting the electric vehicle (EV) via a charging cable (K), several unregulated consumers or loads (L), an energy generation system (PV), and a stationary storage system (SES).
[0045] The photovoltaic system PV and the stationary storage system SES are connected to the smart meter SM via a communication channel COM and receive measured values of the current power (balance) at the grid connection point NCP. The photovoltaic system PV and the stationary storage system SES are controlled in such a way that they attempt to achieve zero-load control at the grid connection point NCP. Furthermore, the charging point EVSE is connected to the smart meter SM via a communication channel COM and also receives measured values of the current power at the grid connection point NCP.
[0046] If the photovoltaic system PV generates surplus energy, this is initially used to charge the stationary storage system SES. If the stationary storage system SES is charged and energy feed-in to the EVN energy distribution grid is to be avoided, the power fed into the local energy grid LOC by the photovoltaic system PV can be reduced, e.g. by reducing the power of a typically existing inverter WR. If the photovoltaic system PV can no longer fully cover the energy demand in the local energy grid LOC, power is taken from the stationary storage system SES. The charging or discharging power of the stationary storage system SES is based on the power balance at the grid connection being zero (zero load).
[0047] In the present method for charging a traction battery BAT of the electric vehicle EV, after the electric vehicle EV has been connected, the charging point EVSE sets a charging power PEL starting from 0 W in such a way that the consumption from the energy distribution network EVN at the grid connection point NCP increases by a specific amount or a specific increment AW, e.g. from AW = 100 W. The charging point EVSE can set the consumption from the energy distribution network EVN using the measurement data from the smart meter SM. In the following, it is assumed that an increase in the consumption generated at the grid connection point NCP corresponds to the charging power PEL at the electric vehicle EV, i.e. an increase in the charging power PEL at the electric vehicle EV by the specific increment AW initially causes an equally large increase in the power consumption from the energy distribution network EVN.
[0048] This deviation from zero load is detected by the photovoltaic system (PV) and the stationary storage system (SES). If the photovoltaic system (PV) or its inverter (WR) is regulated down, the photovoltaic system (PV) can be regulated up again until zero load is present at the grid connection point (NCP). However, if the photovoltaic system (PV) is already feeding its current maximum power into the local energy grid (LOC), power (with a font size of 100 W) is drawn from the stationary storage system (SES) and fed into the local energy grid (LOC) until zero load is present at the grid connection point (NCP). If a zero load is present again at the grid connection point (NCP), this is detected by the EVSE charging point, and the EVSE charging point increases its charging power (PEL) again, in this case constantly by the same increment of AW = 100 W. The photovoltaic system (PV) and the stationary storage system (SES) then attempt to achieve zero load at the grid connection point (NCP) again, and so on.
[0049] This interplay can continue until (a) the maximum charging power PEL is reached or (b) the photovoltaic system PV and the stationary storage system SES deliver maximum power to the local energy grid LOC. When case (b) is reached, the charging point EVSE can determine if the photovoltaic system PV and the stationary storage system SES are no longer able to restore zero load at the grid connection point NCP.
[0050] The EVSE charging point can then maintain the last set charging power PEL, which includes the advantage of particularly effective charging using self-generated renewable energy.
[0051] Fig.2 shows a temporal progression of the charging power PEL in W for charging the traction battery BAT of the electric vehicle EV from Fig.1. The charging power PEL is increased in steps of 100 W until a final charging power PEL of 2000 W is reached, which, together with the power consumed by the loads L, can no longer be fully covered by the photovoltaic system PV and the stationary storage system SES.
[0052] Of course, the present invention is not limited to the embodiment shown.
[0053] In general, "a", "an", etc., can be understood as a singular or a plural, in particular in the sense of "at least one" or "one or more", etc., as long as this is not explicitly excluded, e.g. by the expression "exactly one", etc.
[0054] A numerical specification may also include the exact number specified as well as a usual tolerance range, as long as this is not explicitly excluded.
[0055] BAT drive battery
[0056] COM communication channel
[0057] EVN energy distribution network
[0058] EVSE charging point
[0059] HOME Single-family house
[0060] K Charging cable
[0061] L Unregulated consumer
[0062] LOG Local Energy Network
[0063] N Grid connection point
[0064] PEV charging power
[0065] PV photovoltaic system
[0066] SES stationary storage
[0067] SM Smart Meter t Time
[0068] AW step size
[0069] WR inverter
Claims
Patent claims Method for charging a drive battery (BAT) of at least one electric vehicle (EV) at at least one charging point (EVSE) of a property (HOME) with a local energy network (LOC) which is connected to an energy distribution network (EVN) via a network connection point (NCP) and to which several unregulated consumers (L) as well as the at least one charging point (EVSE), at least one stationary storage device (SES) and at least one energy generation system (PV) are connected, wherein the at least one charging point (EVSE) is designed to specify a charging power (PEL) for charging the drive battery (BAT) of this electric vehicle (EV) after connection of a respective electric vehicle (EV), and wherein in the method - electrical power flowing through the network connection point (NCP) is monitored bidirectionally, - at least one stationary storage system (SES) is operated by means of a zero-load control at the grid connection point (NCP) and - the at least one charging point (EVSE) gradually increases the charging power (PEL) after the electric vehicle (EV) is connected until the at least one stationary storage system (SES) and the at least one energy generation system (PV) achieve their maximum system power, - wherein the steps are selected to be large enough that the stationary storage device (SES) attempts to provide the associated additional system power requirement. Method according to claim 1, wherein the charging power (PEL) is adapted to the currently maximum system power that can be delivered and / or a current consumption of the unregulated consumers (L). Method according to one of the preceding claims, wherein the charging point (EVSE) increases the charging power (PEL) in steps such that a grid connection with a specific step size (AW) is established at the grid connection point (NCP). Method according to one of claims 1 to 2, wherein the charging point (EVSE) increases the charging power (PEL) of the electric vehicle (EV) in steps such that the Charging point (EVSE) increases the charging power (PEL) with a specified step size (AW).
5. Method according to one of the preceding claims, wherein the stepwise increase comprises increasing in steps with a step size (AW) between 50 W and 200 W.
6. Method according to one of the preceding claims, wherein the stepwise increase comprises an increase in steps with a step size (AW) between 0.5% and 2% of a maximum charging power (PEL).
7. Method according to one of the preceding claims, in which a targeted feed-back of energy generated by the at least one energy generation plant (PV) into the energy distribution network (EVN) is prevented.
8. Method according to one of the preceding claims, wherein the at least one energy generation system (PV) comprises a photovoltaic system and / or a wind turbine.
9. Method according to claims 7 and 8, in which at least one energy generation plant (PV) is connected to the local energy grid (LOC) via an inverter (WR) and the inverter (WR) is controlled in such a way that it varies the energy fed into the local energy grid (LOC) by the energy generation plant (PV) for zero-load control.
10. Method according to one of the preceding claims, in which the property is a residential building (HOME), in particular a single-family house.
11. Method according to one of the preceding claims, wherein the charging point (EVSE) is a wallbox.
12. System (HOME, EV) comprising a property (HOME) and an electric vehicle (EV), wherein the electric vehicle (EV) is connectable to a charging point (EVSE) of the property (HOME) to charge its drive battery (BAT), and wherein the system (HOME, EV) is arranged to carry out the method according to one of the preceding claims.