A METHOD FOR CONTROLLING CHARGING OF ELECTRICAL STORAGE DEVICES

Abstract

A method for controlling charging of at least one electrical storage device is disclosed. Information regarding a power grid and the at least one electrical storage device is used by an aggregator to derive a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid by the electrical storage devices. A total power available for charging the at least one electrical storage device is derived in accordance with the weighted distribution by a charging controller. An active power setpoint is derived for each of the at least one electrical storage device on the basis of at least (i) the total available power and (ii) the information regarding the at least one electrical storage device. Finally, a charging state of each of the at least one electrical storage device is controlled based on the derived active power setpoint.

Claims

1. A method for controlling charging of at least one electrical storage device, the method comprising: providing an aggregator arranged in communicative connection with a power grid and the at least one electrical storage device; the aggregator retrieving information regarding the power grid and the at least one electrical storage device; the aggregator deriving a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid by the electrical storage devices, on the basis of the retrieved information; the aggregator providing the derived weighted distribution of virtual inertia response and fast frequency response to a charging controller; the charging controller deriving a total power available for charging the at least one electrical storage device, in accordance with the weighted distribution; deriving an active power setpoint for each of the at least one electrical storage device on the basis of the total available power, and on the basis of the information regarding the at least one electrical storage device; and controlling a charging state of each of the at least one electrical storage device based on the derived active power setpoint.

2. The method of claim 1, wherein at least two electrical storage devices are communicatively connected to the aggregator, and wherein the charging state of the at least two electrical storage devices are being controlled.

3. The method of claim 2, wherein the charging controller is a charging hub controller being arranged to control the charging state of the at least two electrical storage devices.

4. The method of claim 1, wherein at least one of the electrical storage device(s) is an electric vehicle.

5. The method of claim 1, wherein at least one of the electrical storage device(s) is a battery.

6. The method of claim 1, wherein the information regarding the power grid comprises a grid frequency.

7. The method of claim 1, wherein the information regarding the power grid comprises information regarding active power.

8. The method of claim 1, further comprising deriving a current setpoint for each of the at least one electrical storage device based on the derived active power setpoint, and wherein controlling a charging state of each of the at least one electrical storage device is further based on the current setpoint.

9. The method of claim 8, wherein the deriving a current setpoint for each of the at least one electrical storage device includes deriving a duty cycle of a PWM signal.

10. The method of claim 1, wherein at least two electrical storage devices are communicatively connected to the aggregator, and wherein the deriving the active power setpoint for the at least one electrical storage device further comprises: selecting at least one first electrical storage device for providing virtual inertia response and at least one second electrical storage device for providing fast frequency response, in accordance with the weighted distribution, and on the basis of the information regarding the electrical storage devices; deriving an active power setpoint for each of the first electrical storage devices being purely virtual inertia response; and deriving an active power setpoint for each of the second electrical storage devices being purely fast frequency response.

11. The method of claim 1, wherein the information regarding the at least one electrical storage device is provided to the aggregator by a Software-as-a-service (SaaS) platform.

12. The method of claim 1, wherein the controlling a charging state of each of the at least one electrical storage device comprises charging at least one of the at least one electrical storage device.

13. The method of claim 1, wherein the controlling a charging state of each of the at least one electrical storage device comprises discharging at least one of the at least one electrical storage device, thereby providing active power support to the power grid.

14. The method of claim 13, wherein at least one of the at least one electrical storage device is an electric vehicle with bidirectional charging capability, wherein the information regarding the at least one electrical storage device comprises information regarding the charging state of the electric vehicle with bidirectional charging capability, and wherein the discharging the electric vehicle is only performed if the charging state of the electric vehicle is above a predefined threshold value.

15. The method of claim 1, wherein the information regarding the at least one electrical storage device comprises information regarding the charging state for at least some of the at least one electrical storage device.

16. The method of claim 1, wherein the deriving a weighted distribution of virtual inertia response and fast frequency response is repeated at predefined time intervals.

17. (canceled)

18. A system for charging at least one electrical storage device, the system comprising: an aggregator being configured to retrieve information from a power grid and the at least one electrical storage device, and to derive, on the basis of the retrieved information, a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid; a charging controller arranged in communication with the aggregator to receive the derived weighted distribution, and configured to derive, from the received derived weighted distribution, a total power available for charging and an active power setpoint for each of the at least one electrical storage device, wherein the charging of the at least one electrical storage device is controlled in accordance with an operation, comprising: deriving an active power setpoint for each of the at least one electrical storage device on the basis of the total available power, and on the basis of the information regarding the at least one electrical storage device; and controlling a charging state of each of the at least one electrical storage device based on the derived active power setpoint.

19. The system of claim 18, wherein the charging controller is a charging hub controller being arranged to control the charging state of the at least two electrical storage devices.

20. The system of claim 18, wherein at least one of the electrical storage device(s) is an electric vehicle.

21. The system of claim 18, wherein at least one of the electrical storage device(s) is a battery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0114] The invention will now be described in further details with reference to the accompanying drawings, in which

[0115] FIG. 1 is a block diagram illustrating a method according to a first embodiment of the invention,

[0116] FIG. 2 is a block diagram illustrating a method according to a second embodiment of the invention,

[0117] FIG. 3 is a flow chart illustrating a method according to an embodiment of the invention,

[0118] FIG. 4 is a schematic diagram illustrating a system according to an embodiment of the invention,

[0119] FIG. 5 is a block diagram illustrating a method according to an embodiment of the invention, and

[0120] FIG. 6 is a diagrammatic illustration of a method according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0121] FIG. 1 is a block diagram illustrating a method according to a first embodiment of the invention. An aggregator 1 is in communicative connection with a charging hub SaaS 2 and a charging hub controller 4. The charging hub controller 4 is arranged to control the charging state of at least one electrical storage device 5, which could, e.g., be in the form of one or more electric vehicles.

[0122] The charging hub SaaS 2 is in communicative connection with the electrical storage device 5 and is therefore capable of obtaining information regarding the electrical storage device 5, e.g. in the form of charging pattern, a power capacity, charging state, availability for charging, etc.

[0123] The charging hub SaaS 2 is further in communicative connection with an external application 6, in which the charging hub SaaS 2 and the external application 6 are able to provide information to each other. The external application 6 may be a software application in the form of, e.g., an app, installed on a mobile device, such as a cell phone, a tablet or a laptop computer. Thus, it is possible for a user of the electrical storage device 5, or the like, to manually provide further information regarding the electrical storage device 5, such as expected availability of the electrical storage device 5, time constraints for fully charge of the electrical storage device 5, etc. to the charging hub SaaS 2, using the external application 6.

[0124] Thus, the charging hub SaaS 2 obtains various information regarding the electrical storage devices 5 from various sources, notably directly from the electrical storage devices 5 and from the external application 6.

[0125] The retrieved information regarding the electrical storage device 5 is provided from the charging hub SaaS 2 to the aggregator 1.

[0126] The aggregator 1 further receives various measurements 3. The measurements 3 may, e.g., be measurements from a power grid (not shown), e.g. in relating to frequency, active power, reactive power, voltage, market information, and/or other kinds of measurements which provide information regarding the state of the power grid.

[0127] Thus, the aggregator 1 receives information regarding the electrical storage devices 5, via the charging hub SaaS 2, as well as information regarding the power grid.

[0128] Based on this information, the aggregator 1 derives a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid. The weighted distribution is a measure for the ratio between virtual inertia response and fast frequency response which the at least one electrical storage device 5 has to provide to the power grid.

[0129] The derived weighted distribution is provided from the aggregator 1 to the charging hub controller 4. As described above, the charging hub controller 4 is arranged to control the charging state of at least one electrical storage device 5.

[0130] The charging hub controller 4 further receives information regarding the electrical storage device 5 from the charging hub SaaS 2.

[0131] Thus, the charging hub controller 4 receives the weighted distribution via the aggregator 1, and further receives information regarding the electrical storage devices 5, via the charging hub SaaS 2.

[0132] The charging hub controller 4 derives a total power available for charging the at least one electrical storage device 5, in accordance with the weighted distribution, and using a control algorithm 7. The total power available is a measure of the amount of power which the charging hub controller 4 has at its disposal for charging the at least one electrical storage device 5. Since the total available power is derived based on the weighted distribution, it reflects this distribution, and is therefore a measure of the amount of virtual inertia response and fast frequency response to be provided to the power grid by the electrical storage device 5.

[0133] The derived total available power is provided from the control algorithm 7 to a dispatcher 8. The dispatcher 8 is arranged to dispatch the total available power among the electrical storage device(s) 5, based on the total available power and on the basis of the information regarding the electrical storage device(s) 5, which was received from the charging hub SaaS 2. Thus, the dispatcher 8 determines how the total available power is to be distributed among the electrical storage device(s) 5, in order to fulfil requirements of the power grid, notably with respect to the ratio of virtual inertia response and fast frequency response, as well as in order to fulfil requirements of the individual electrical storage device 5, and ensures that the total available power is actually distributed in this manner.

[0134] Thus, the dispatcher 8 derives an active power setpoint for each of the electrical storage devices 5 based on the total available power, and on the basis of the information regarding the electrical storage device 5. Each of the active power setpoints derived in this manner represents a setpoint which specifies how the charging state of a given electrical storage device must be controlled. Since the active power setpoints are derived on the basis of the total available power, which reflects the weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid, the active power setpoints also reflect this weighted distribution. It is therefore ensured that all of the active power setpoints, in combination, reflect the weighted distribution, even though it may not be reflected separately by each of the active power setpoints.

[0135] The derived active power setpoint for each of the electrical storage devices 5 is provided from the charging hub controller 4 to the corresponding electrical storage device 5. Finally, the charging state of each of the electrical storage devices 5 is controlled based on the respective active power setpoints. Thereby it is ensured that the charging states of the electrical storage devices 5, in combination, are controlled in a manner which ensures that the required weighted distribution of virtual inertia response and fast frequency response is actually provided to the power grid. Accordingly, the electrical storage devices 5 may replace conventional inertia providing units with regard to ensuring stability of the power grid, and thereby it is possible to increase the penetration of renewable energy generators in the power grid.

[0136] FIG. 2 is a block diagram illustrating a method according to a second embodiment of the invention. An aggregator 1 is in communicative connection with a charging hub SaaS 2 and a power management block 9 forming part of a charging controller 4. The charging controller 4 is arranged to control the charging state of at least one electrical storage device. In FIG. 2, one of the electrical storage devices is in the form of a battery, and the remaining electrical storage devices, two of which are indicated, are in the form of electrical vehicles.

[0137] The charging hub SaaS 2 is capable of obtaining information regarding the electrical storage device, e.g. in the form of charging pattern, a power capacity, charging state, availability for charging, etc. This could, e.g., be obtained in the manner described above with reference to FIG. 1, i.e. via a direct communicative connection with the electrical storage device and/or via an external application.

[0138] Thus, the charging hub SaaS 2 obtains various information regarding the electrical storage device from various sources, e.g. directly from the electrical storage device.

[0139] The retrieved information regarding the electrical storage device is provided from the charging hub SaaS 2 to the aggregator 1.

[0140] The aggregator 1 further receives frequency measurements. The frequency measurements may, e.g., be a frequency measured in a power grid (not shown). Other kinds of measurements which provide information regarding the state of the power grid, such as frequency, active power, reactive power, voltage, market information, etc., may also be measured and provided to the aggregator 1.

[0141] Thus, the aggregator 1 receives information regarding the electrical storage devices, via the charging hub SaaS 2, as well as information regarding the frequency, and possibly further information regarding the power grid.

[0142] Based on this information, the aggregator 1 derives a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid. The weighted distribution is a measure for the ratio between virtual inertia response and fast frequency response which the at least one electrical storage device has to provide to the power grid.

[0143] The derived weighted distribution is provided from the aggregator 1 to the power management block 9. The power management block 9 further receives information regarding the electrical storage devices, from the charging hub SaaS 2.

[0144] The power management block 9 is arranged to provide the weighted distribution received by the aggregator 1 to a control algorithm 7, in the form of a combined inertia-fast frequency control, of the charging controller 4. The power management block 9 further provides additional information regarding active power limits and active power/frequency correlation to the control algorithm 7.

[0145] The charging hub controller 4 derives a total power available for charging the at least one electrical storage device, in accordance with the weighted distribution, and using the control algorithm 7, e.g. in the manner described above with reference to FIG. 1. The total power available is a measure of the amount of power which the charging hub controller 4 has at its disposal for charging the at least one electrical storage device. Since the total available power is derived based on the weighted distribution, it reflects this distribution, and is therefore a measure of the amount of virtual inertia response and fast frequency response to be provided to the power grid by the electrical storage device.

[0146] The derived total available power is provided from the control algorithm 7 to a dispatch block 8 forming part of the charging controller 4. The dispatch block 8 further receives information regarding the electrical storage devices from the charging hub SaaS 2.

[0147] Based on the total available power and the information regarding the electrical storage devices, the dispatch block 8 derives an active power setpoint for each of the electrical storage devices.

[0148] The derived active power setpoint related to the battery is supplied to a battery control system 11. Based thereon, the battery control system 11 provides a setpoint to a power conversion system (PCS). The setpoint provided to the PCS may, e.g., be the active power setpoint. As an alternative, it may be another kind of setpoint, which is derived from the active power setpoint. The charging state of the battery is then controlled based on the provided setpoint.

[0149] The active power setpoints related to the electric vehicles are provided to respective current setpoint calculation blocks 10.

[0150] The current setpoint calculation blocks 10 each derives a current setpoint for the corresponding electric vehicle based on the received active power setpoint. Each of the current setpoints derived in this manner represents a setpoint which specifies how the charging state of a given electrical storage device must be controlled.

[0151] The current setpoints are then supplied from the respective current setpoint calculation blocks 10 or corresponding duty cycle calculation blocks 12. The duty cycle calculation blocks 12 are arranged to derive a duty cycle of a PWM signal for the corresponding electric vehicle based on the received current setpoint. The duty cycle is the fraction of one period in which, e.g., a signal is active, wherein a period may be the time it takes for a signal to complete an on-and-off cycle. Thus, each duty cycle calculation block 12 determines the charging state of the corresponding electric vehicle. The charging states of the electric vehicles are then controlled in accordance with the respective duty cycles.

[0152] Since the active power setpoint for the battery and the duty cycles for the electric vehicles are derived on the basis of the active power setpoints, and the active power setpoints are derived on the basis of the total available power, which reflects the weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid, it is ensured that all of the setpoints applied when controlling the charging states of the electrical storage devices, in combination, reflect the weighted distribution, even though it may not be reflected separately by each of the setpoints. Thereby, the electrical storage devices may replace conventional inertia providing units with regard to ensuring stability of the power grid, similarly to the situation described above with reference to FIG. 1.

[0153] FIG. 3 is a flow chart illustrating a method according to an embodiment of the invention. The method is initiated at step 13, in which information regarding a power grid and at least one electrical storage device is retrieved by an aggregator.

[0154] At step 14, the aggregator derives a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid by the electrical storage device, on the basis of the retrieved information. The derived weighted distribution is thereafter provided to a charging controller together with the retrieved information.

[0155] At step 15, the charging controller derives a total available power for charging the at least one electrical storage device, in accordance with the weighted distribution. The total available power is a measure of the amount of power which the charging controller has at its disposal for charging the at least one electrical storage device.

[0156] At step 16, an active power setpoint for each of the at least one electrical storage device is derived on the basis of the total available power, and on the basis of the information regarding the at least one electrical storage device. The active power setpoint is a control parameter which indicates how the charging state of a given electrical storage device is to be controlled, including the amount of virtual inertia response and fast frequency response to be provided by each electrical storage device to the power grid.

[0157] At step 17, the charging state of each of the at least one electrical storage device is controlled based on the derived active power setpoint, e.g. in the manner described above with reference to FIG. 1 or 2.

[0158] FIG. 4 is a diagram illustrating a system according to an embodiment of the invention. An aggregator 1, a charging hub SaaS 2 and a charging hub controller 4 are in communicative connection, e.g. in the manner described above with reference to FIG. 1 or 2.

[0159] The aggregator 1 receives grid measurements 18 via the charging hub controller 4. The grid measurements 18 may, e.g., be a frequency measured in a power grid. Other kinds of measurements which provide information regarding the state of the power grid, such as active power, reactive power, voltage, market information, etc., may also be measured and provided to the aggregator 1.

[0160] The aggregator 1 further receives information regarding at least two electric vehicles 21 and at least two batteries 22 via the charging hub SaaS 2, e.g. in the manner described above with reference to FIG. 1 or 2. The information regarding the electric vehicle 21 provided by the charging hub SaaS 2 could, e.g., include information regarding availability of the electric vehicle 21, a degradation model of the electric vehicle 21, and/or a minimum/maximum state of charge required by the electric vehicle 21. Such information could, e.g., be provided manually to the charging hub SaaS 2 by an owner or a user of the vehicle 21. The information provided by the charging hub SaaS 2 to the aggregator 1 may be used for optimization purposes only, in which case the aggregator 1 may obtain any information required in order to operate from other sources. Alternatively, the information provided by the charging hub SaaS 2 may be necessary for operation purposes.

[0161] Based on the received information, the aggregator 1 derives a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid. The weighted distribution is a measure for the ratio between virtual inertia response and fast frequency response which the at least one electrical storage device has to provide to the power grid.

[0162] The derived weighted distribution is provided from the aggregator 1 to the charging hub controller 4.

[0163] The charging hub controller 4 further receives grid measurements 18, e.g., in the form of frequency, active power, reactive power, voltage, market information, and/or other kinds measurements which provide information regarding the state of the power grid.

[0164] The charging hub controller 4 is further in communicative connection with a number of EV charging stations 19, two of which are shown, and a number of battery controls 20, two of which are shown. Thus, the charging hub controller 4 is capable of providing information to and receiving information from each of the EV charging stations 19 and each of the battery controls 20.

[0165] Thus, the charging hub controller 4 obtains various information from the aggregator 1, the charging hub SaaS 2, the EV charging station 19, the battery control 20, and the power grid, in the form of the grid measurement 18.

[0166] The charging hub controller 4 derives a total power available for charging the electric vehicles 21 and the batteries 22, in accordance with the weighted distribution, and based on the received information. The total power available is a measure of the amount of power which the charging hub controller 4 has at its disposal for charging the electric vehicles 21 and batteries 22. Since the total available power is derived based on the weighted distribution, it reflects this distribution, and is therefore a measure of the amount of virtual inertia response and fast frequency response to be provided to the power grid by the electric vehicles 21 and batteries 22.

[0167] The charging hub controller 4 further derives an active power setpoint for each of the EV charging stations 19 and each of the battery controls 20 based on the total available power, and on the basis of the information regarding the electric vehicles 21 and the batteries 22. Each of the active power setpoints specifies how the charging state of a given electric vehicle 21 or a given battery 22 must be controlled. Since the active power setpoints are derived on the basis of the total available power, which reflects the weighted distribution, the active power setpoints in combination also reflect this weighted distribution. It is therefore ensured that the combination of all active power setpoints reflects the weighted distribution, even though it may not be reflected separately by each of the active power setpoints.

[0168] The derived active power setpoints for each of the EV charging stations 19 and each of the battery controls 20 are provided from the charging hub controller 4 to the corresponding EV charging stations 19 and battery controls 20. Finally, the charging state of each of the electrical vehicles 21 and each of the batteries 22 are controlled based on the respective active power setpoints. Thereby, it is ensured that the charging states of the vehicles 21 and batteries 22, in combination, are controlled in a manner which ensures that the required weighted distribution of virtual inertia response and fast frequency response is actually provided to the power grid. Thereby the electric vehicles 21 and the batteries 22 may replace conventional inertia providing units with regard to ensuring stability of the power grid, similarly to the situation described above with reference to FIG. 1.

[0169] FIG. 5 is a block diagram illustrating a method according to an embodiment of the invention. A charging hub SaaS 2 is in communicative connection with an electrical storage device in the form of an electric vehicle 21 and a mobile device 23, such as a cell phone, a tablet or a laptop computer, possibly having appropriate software, e.g. in the form of an external application, installed thereon. The charging hub SaaS 2 is further in communicative connection with a dispatch block 8.

[0170] The charging hub SaaS 2 and the dispatch block 8 may, e.g., form part of the system illustrated in FIG. 1 or the system illustrated in FIG. 2, and they will therefore not be described in further detail here.

[0171] The charging hub SaaS 2 receives information regarding the electric vehicle 21 directly from the electric vehicle 21. This could, e.g., be by the electric vehicle 21 communicating relevant information, such as state of charge, state of health, etc., to the charging hub SaaS 2, e.g. by the electric vehicle 21, or a charging station to which the electric vehicle 21 is connected, pushing this information to the charging hub SaaS 2. Alternatively or additionally, the charging hub SaaS 2 may retrieve this information, e.g. by monitoring the electric vehicle 21 or by contacting the electric vehicle 21 at specific points in time.

[0172] The state of charge indicates the level of charge of the electric vehicle 21 relative to its power capacity, i.e., how much energy is stored in the electric vehicle 21, and how much free storing capacity each electrical storage device possesses.

[0173] The state of health indicates the condition of a battery and its ability to deliver a specified performance, compared to its ideal conditions, i.e. how much of the available lifetime energy throughput of the battery has been consumed, and how much is left.

[0174] Furthermore, the charging hub SaaS 2 receives information regarding the electric vehicle 21 from the mobile device 23. Such information may be provided manually by a user or an owner of the electric vehicle 21, e.g. by the user or owner entering the information via an app running on the mobile device 23. Such information may advantageously relate to expected availability of the electric vehicle 21, time constraints for fully charge of the electric vehicle 21, subscription plans of the electric vehicle 21, etc.

[0175] Thus, information regarding the current state of the electric vehicle 21 may be provided and/or monitored by the charging hub SaaS 2, and information regarding the use of the electric vehicle 21 may be manually provided by the owner or user of the electric vehicle 21 via a mobile device 23.

[0176] FIG. 6 is a diagrammatic illustration of a method according to an embodiment of the invention. A grid frequency is compared to a desired setpoint for the grid frequency, e.g. in the form of a nominal grid frequency, at comparator 24. Thereby a frequency deviation is derived. At 25 it is investigated whether or not the frequency deviation is within a specified frequency deadband, and at 26 a frequency droop is obtained. Based thereon, a power setpoint which represents a required fast frequency response is derived and supplied to summation point 27.

[0177] Furthermore, a gradient of the frequency deviation is obtained at 28, thereby obtaining a rate of change of frequency (RoCoF). At 29 it is investigated whether or not the RoCoF is within a specified RoCoF deadband, and at 30 a RoCoF droop is obtained. Based thereon, a power setpoint which represents a required virtual inertia response is derived and supplied to the summation point 27.

[0178] At summation point 27, at total power setpoint is derived, based on the received power setpoints representing required fast frequency response and virtual inertia response, respectively. The total power setpoint, thus, reflects a weighted distribution of virtual inertia response and fast frequency response to be provided to the power grid.

[0179] The derived total power setpoint is subsequently applied for generating individual power setpoints for electrical storage devices which are to be controlled in order to provide the required fast frequency response and virtual inertia response.