Method for operating a charging station

Abstract

A method for operating a charging station for charging a plurality of electric vehicles, in particular electric cars, wherein the charging station is connected at a grid connection point to an electrical supply grid in order to be supplied with electrical energy from the electrical supply grid via said grid connection point, comprising the steps of drawing electrical energy from the electrical supply grid and charging one or more electric vehicles using the electrical energy drawn from the electrical supply grid, wherein the charging station is controlled in such a way that the electrical supply grid is electrically supported.

Claims

1. A method comprising: operating a charging station for charging a plurality of electric vehicles, wherein the charging station is coupled to an electrical supply grid at a grid connection point, wherein the charging station is configured to receive an electrical energy from the electrical supply grid via the grid connection point, wherein the operating comprises: drawing electrical energy from the electrical supply grid, and charging one or more electric vehicles using the electrical energy drawn from the electrical supply grid, wherein the charging station is controlled in such a way that the electrical supply grid is electrically supported, wherein the drawing of the electrical energy is controlled depending on at least one of: a grid state or a grid characteristic of the electrical supply grid, wherein the grid state indicates at least one state of the electrical supply grid selected from the list comprising: a grid frequency, a grid frequency change, a grid voltage, a grid voltage change, and a harmonic content of the grid voltage, wherein the grid characteristic indicates at least one characteristic of the electrical supply grid selected from the list comprising: a grid sensitivity defined as a voltage response of the electrical supply grid at the grid connection point to a changed power removal of the charging station at the grid connection point, and a short circuit current ratio defined as a ratio of a maximum short circuit current providable by the electrical supply grid at the grid connection point in relation to a nominal power removable by the charging station.

2. The method as claimed in claim 1, wherein the drawing of the electrical energy is controlled in such a way that the electrical supply grid is electrically supported.

3. The method as claimed in claim 1, wherein the drawing of electrical energy is controlled depending on power values provided as reference values by one or more external signals.

4. The method as claimed in claim 1, wherein the drawing of the electrical energy is controlled in such a way that power is drawn from the supply grid depending on the grid frequency.

5. The method as claimed in claim 1 further comprising feeding reactive power from or into the supply grid depending on at least one of: a grid state or a specification by a grid operator of the supply grid.

6. The method as claimed in claim 1, further comprising: maintaining the charging station coupled to the supply grid in an event of a grid fault, and removing or feeding electrical power from or into the supply grid depending on at least one of: a grid state or a specification by a grid operator, wherein the charging station is controlled in such a way that the charging station draws as much power from the supply grid after the grid fault as the charging station drew immediately before the grid fault.

7. The method as claimed in claim 1, wherein the charging station is controlled in such a way that the charging stations feeds electrical power from an electric storage device of the charging station into the supply grid depending on at least one of: a grid state or a specification by a grid operator.

8. The method as claimed in claim 1, wherein the charging station provides an instantaneous reserve depending on at least one of: a grid frequency or a change in the grid frequency, wherein the charging station is configured to: reduce power instantaneously removed from the supply grid, and feed power from an electric storage device of the charging station into the supply grid.

9. The method as claimed in claim 8, further comprising: drawing additional power from the supply grid depending on the grid frequency or the change in the grid frequency, wherein the charging station consumes the additional power from the supply grid, wherein: the charging station increases the power instantaneously removed from the supply grid to store more power in the electric storage device of the charging station and increases the power to charge the one or more electric vehicles, and consumes power in an additional consumer in a chopper system which guides electrical power in a targeted manner into a resistance arrangement comprising one or more electrical resistors that are configured to consume the power in a thermal manner.

10. The method as claimed in claim 9, wherein additionally or less required power is provided or taken by at least one measure from the list comprising: use of the electric storage device of the charging station, variation in charging power of the electric vehicle to be charged in each case, and control of further consumers of the charging station.

11. The method as claimed in claim 1, wherein the drawing of electrical energy from the supply grid comprises removing electrical power from the supply grid, the method further comprising: specifying at least one change limit to limit changes in the electrical power in terms of rate of change, such that at least one of: a common gradient, an upper limit gradient, or a lower limit gradient are specified to limit a temporal increate or a temporal decrease in the power.

12. The method as claimed in claim 1, wherein one or more of the following are controlled using a virtual storage device: the drawing of electrical energy from the supply grid, the charging of the electric vehicles, a control of further consumers of the charging station, and a feed-in of electrical power into the supply grid, wherein the virtual storage device takes account of: an amount of power the charging station is able to provide for charging the electric vehicles and for feed-in to the supply grid, as charged storage capacity, and an amount of power the charging station is able to take from the supply grid, as chargeable storage capacity.

13. The method as claimed in claim 1, wherein a maximum power to be removed from the supply grid is specifiable in a fixed or variable manner, wherein: a fixed specification is performed by an external signal by a grid operator, and a variable specification is performed depending on at least one of: the grid characteristic or the grid state.

14. The method as claimed in claim 1, wherein at least one of: at least one operational state of at least one windfarm coupled to the charging station or to the supply grid is taken into account, or the at least one windfarm is at least partially controlled by the charging station or by an overall control unit superordinate to the charging station and to the at least one windfarm.

15. The method as claimed in claim 1, wherein the charging station and at least one windfarm configured to at least one of: control a power flow in the supply grid, or support a voltage regulation in the supply grid.

16. A charging station for charging electric vehicles, wherein the charging station is configured to perform the method as claimed in claim 1.

17. A method comprising: operating a charging station for charging a plurality of electric vehicles, wherein the charging station is coupled to an electrical supply grid at a grid connection point, wherein the charging station is configured to receive an electrical energy from the electrical supply grid via the grid connection point, wherein the operating comprises: drawing electrical energy from the electrical supply grid, and charging one or more electric vehicles using the electrical energy drawn from the electrical supply grid, wherein the charging station is controlled in such a way that the electrical supply grid is electrically supported, wherein the charging station provides an instantaneous reserve depending on at least one of a grid frequency or a change in the grid frequency, wherein the charging station is configured to: reduce power instantaneously removed from the supply grid, and feed power from an electric storage device of the charging station into the supply grid, the method further comprising: drawing additional power from the supply grid depending on the grid frequency or the change in the grid frequency, wherein the charging station consumes the additional power from the supply grid, wherein the charging station increases the power instantaneously removed from the supply grid to store more power in the electric storage device of the charging station and increases the power to charge the one or more electric vehicles, and wherein consumes power in an additional consumer in a chopper system which guides electrical power in a targeted manner into a resistance arrangement comprising one or more electrical resistors that are configured to consume the power in a thermal manner.

18. The method as claimed in claim 17, wherein additionally or less required power is provided or taken by at least one measure from the list comprising: use of the electric storage device of the charging station, variation in charging power of the electric vehicle to be charged in each case, and control of further consumers of the charging station.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention is explained in detail below by way of example on the basis of embodiments with reference to the accompanying figures.

(2) FIG. 1 shows a wind power installation in a perspective view.

(3) FIG. 2 shows a windfarm in a schematic view.

(4) FIG. 3 shows an active-reactive power diagram divided into four quadrants.

(5) FIG. 4 shows schematically a charging station and parts of an electrical supply grid.

DETAILED DESCRIPTION

(6) FIG. 1 shows a wind power installation 100 with a tower 102 and a nacelle 104. A rotor 106 with three rotor blades 108 and a spinner 110 is disposed on the nacelle 104. The rotor 106 is set in rotational motion by the wind and thereby drives a generator in the nacelle 104.

(7) FIG. 2 shows a windfarm 112 with, by way of example, three wind power installations 100, which may be identical or different. The three wind power installations 100 thus represent essentially any number of wind power installations of a windfarm 112. The wind power installations 100 provide their power, i.e., in particular, the generated current, via an electrical windfarm grid 114. The currents or powers of the individual wind power installations 100 generated in each case are added together and a transformer 116 is usually provided to step up the voltage in the windfarm and then feed it at the feed-in point 118, which is also generally referred to as the PCC, into the supply grid 120. FIG. 2 is only a simplified representation of a windfarm 112 which, for example, shows no controller, although a controller is obviously present. The windfarm grid 114 can also, for example, be designed differently in that, for example, a transformer is also present at the output of each wind power installation 100, to mention but one other example embodiment.

(8) The diagram in FIG. 3 shows for illustrative purposes an active-reactive power diagram for a power feed-in. The active power P is plotted on the x-axis and the reactive power Q is plotted on the y-axis. Standardized values are indicated as values, wherein the standardization can be based, for example, on the amount-related value of the nominal power of a charging station. However, the precise values are not relevant here in this illustration.

(9) The diagram is intended to illustrate operating ranges at a charging station connected to an electrical supply grid. A charging station according to FIG. 3 can be used as a basis and will be described in detail below.

(10) The range resulting from the use of an uncontrolled rectifier is designated as the uncontrolled range 300. In this case, the charging station would remove an active power P from the electrical supply grid by means of the uncontrolled rectifier, said active power corresponding, in particular, to the respectively present requirement. A charging station of this type this only removes active power whose amplitude fluctuates from zero to nominal power. Since the diagram in FIG. 3 has been chosen as a diagram of a feed-in, the range therefore extends from the value 0 to −1. It is plotted as a range around the x-axis, but is shown only for illustrative purposes. The theoretical value can essentially lie on the x-axis.

(11) In any case, no reactive power is fed in or removed according to this uncontrolled range 300, so that this uncontrolled range 300 is essentially shown only as a path on the x-axis. This uncontrolled range 300 thus shows a range according to the prior art. However, this representation is also illustrative insofar as a reactive power component can be present during an uncontrolled operation also. The uncontrolled range 300 could then be shown as a straight line into the 2nd or 3rd quadrant.

(12) If at least one controlled rectifier is now used and the charging station is controlled in such a way that the electrical supply grid is electrically supported, the charging station can be operated at least in the controlled range at the first stage 310. This controlled range at the first stage 310 is shown as a semicircle with a dotted-line boundary. It shows that the charging station can be operated in the second and third quadrant according to the chosen nomenclature of FIG. 3. The four quadrants shown are continuously numbered using Roman numerals.

(13) According to this controlled range at the first stage 310, the charging station can thus be controlled not only in such a way that active power can be removed from the electrical grid, but also in such a way that reactive power can also be fed in or removed. The power or energy which is drawn from the electrical supply grid is removed with a removal current. The removal current can also be referred to as the consumption current. According to the first-stage controlled range, this removal current I.sub.V can have a phase angle φ in relation to the grid voltage, i.e., the electrical voltage in the electrical supply grid. If this phase angle φ has the value zero, only active power is removed and this would corresponds to the uncontrolled range 300. A situation of this type could also be described mathematically in such a way that the removal current I.sub.V corresponds to a feed-in current with a phase angle of −180° or +180°. However, the representation of a removal current I.sub.V has been chosen here for clearer illustration.

(14) If this phase angle φ now has a value of −90° to +90°, it is located in the second or third quadrant and therefore in the controlled range at the first stage 310. This controlled range at the first stage 310 is shown here as a semicircle, i.e., under the idealizing assumption that the phase angle can assume the full 180°, i.e., from −90° to +90°, and under the assumption that it can attain, but cannot also exceed, this value which corresponds to the radius of the shown circle, for each phase angle.

(15) However, with a phase angle which does not correspond to the value zero, it is also conceivable for the removal current I.sub.V to be greater. It is conceivable, for example, that only the active power has the shown restriction and an apparent power which is higher in terms of amount than the maximum active power can be fed in. In this case, an active power reduction does not necessarily have to take place with a non-zero phase angle φ.

(16) However, with a phase angle of 90° or −90°, it is also conceivable that more full reactive power, i.e., reactive power with the amplitude standardized to the nominal power, cannot necessarily be fed in. In this case, the semicircle shown for illustrative purposes would not attain the value 1 or −1 for the controlled range at the first stage 310 on the y-axis.

(17) In any case, FIG. 3 illustrates that the charging station can nevertheless feed in or remove a reactive power, even if it is prepared for active power removal only, by influencing the phase angle of the removal current I.sub.V.

(18) According to at least one design, an extension is proposed according to which the charging station can also be operated in a controlled range at a second stage 320. This second-stage controlled range is limited for illustrative purposes with a dotted-and-dashed line which similarly shows a semicircle. However, this is actually intended to be understood in such a way that the controlled range at the second stage 320 also comprises the controlled range at the first stage 310. The second-stage controlled range therefore comprises all four quadrants.

(19) Such an extension of the charging station is achieved, in particular, through the use of an electric storage device which can also be referred to as a precharging storage device. It is therefore then also possible to feed active power into the electrical supply grid. Such a feed-in of active power is achieved by means of a feed-in current I.sub.e. Such a feed-in current I.sub.e can have a phase angle φ.sub.e. The feed-in current I.sub.e can essentially also be explained with reference to the removal current I.sub.V if its phase angle φ is extended onto a range from −180° to +180°. However, such a mathematically correct representation offers little clarity, so that the feed-in is based on the feed-in current I.sub.e.

(20) Active power can be fed in by the charging station even in this controlled range at the second stage 320. However, a reactive power feed-in or removal is furthermore possible in this range also, i.e., in the first and fourth quadrant. The circular shape is to be understood merely as an idealization for this controlled range at the second stage 320 also. However, this circular shape can nevertheless also represent an important specific application, particularly if the amount of the feed-in current I.sub.e is limited due to a current limitation, regardless of the chosen feed-in phase angle φ.sub.e.

(21) All four quadrants of the feed-in diagram shown in FIG. 3 can thus be covered with the controlled second-stage range. The charging station can thereby carry out a variety of support measures.

(22) An extended active power range 330 which can be achieved by an additional consumer in the charging station is also indicated by way of illustration in FIG. 3. Such an extended active power range 330 thus enables the removal from the electrical supply grid of a power extending beyond the nominal power of the charging station if this is necessary for support purposes. However, this extended active power range 330 is also to be understood as illustrative and cannot obviously be attained if a current limitation of the grid connection point limits an active power removal to the nominal active power of the charging station, corresponding to the value −1 on the x-axis.

(23) However, an increased active power removal by a consumer of this type can also be appropriate if the uncontrolled range 300 of the charging station cannot be fully exhausted because the charging station does not instantaneously have sufficient available power consumers, i.e., vehicles to be charged. In this case, the uncontrolled range 300 would not attain the value −1, but it could also be attained by the additional consumer. In this respect, FIG. 3 also illustrates the possibility that the controlled active power range 330 can be added to the uncontrolled range 300 according to the prior art in such a way that this combination then attains only the value −1.

(24) FIG. 4 shows schematically a charging station 400 which is connected via a grid connection point 402 to an electrical supply grid 404. This electrical supply grid 404 is shown here symbolically only and can also be referred to merely as a grid for the sake of simplicity.

(25) The grid connection point 402 has a grid transformer 406. The charging station 400 draws electrical energy from the grid 404 via said transformer. This is essentially effected by means of a controlled power removal. The bidirectional inverter 408 is provided for this purpose. In normal operation, this bidirectional inverter 408 converts three-phase AC current from the supply grid 404 into a DC current. This DC current can be provided in an intermediate DC voltage circuit 410 which is indicated here as the output of the bidirectional inverter 408.

(26) The electrical power removal can also be controlled via this bidirectional inverter 408 in such a way that the phase angle φ of a removal current I.sub.V can also be set in relation to the grid voltage V.sub.N. The grid voltage V.sub.N is shown here for the sake of simplicity at a measuring point between the grid transformer 406 and the bidirectional inverter 408. A corresponding grid voltage of the electrical supply grid 404 on the other side of the grid transformer 406 is created accordingly by the transmission ratio of the grid transformer 406.

(27) The bidirectional inverter 408 proposed here can furthermore also feed power into the electrical supply grid 404. The bidirectional inverter 408, which can also be referred to here merely as the inverter for the sake of simplicity, can thus generate a feed-in current I.sub.e opposed to the removal current I.sub.V. Obviously, only the removal current I.sub.V or the feed-in current I.sub.e flows.

(28) The fundamental purpose of the bidirectional inverter 408 is to draw electrical energy from the grid 404, i.e., by removing electrical power from the grid 404. This power is provided in the intermediate DC voltage circuit 410, i.e., essentially in the distributor circuit 412. The distributor circuit 412 is shown as a DC-DC converter in order to illustrate that it receives a DC current as input and forwards it to individual charging poles 414 according to requirements. Three charging poles 414 are shown by way of illustration, representing many charging poles 414. In each case, an electric vehicle 416 is intended to be charged presently at a charging pole 414. Obviously, it is essentially also conceivable that an electric vehicle 416 is not always connected to each charging pole 414.

(29) The distribution by means of the distributor circuit 412 is similarly to be understood merely as illustrative and it is conceivable, for example, that each charging pole 414 on its own controls its charging controller and also an energy allocation available to it and a charging pole 414 of this type could also be connected in each case directly to the intermediate DC voltage circuit 410 for this purpose. However, a distributor circuit 412 of this type is preferably proposed which also performs a voltage reduction to the voltage level of an electric vehicle 416.

(30) In addition to this distributor circuit 412 which supplies the charging poles 414, a battery bank 418 is also shown which can similarly be connected to the intermediate DC voltage circuit 410. This battery bank 418 is thus an electric storage device. It can serve as an energy buffer in order to balance load peaks due to the charging of the electric vehicles 416 so that load peaks, i.e., power peaks, of this type are not, or are not entirely, forwarded to the electrical supply grid 404. However, the battery bank 418, here representing an electric storage device, can also be used to feed electrical power into the electrical supply grid 404, i.e., by means of the feed-in current I.sub.e. An operation in the first and fourth quadrant according to the diagram shown in FIG. 3 is therefore also possible by means of a battery bank 418 of this type.

(31) A chopper system 420 is furthermore connected to the intermediate DC voltage circuit 410. For simplification, this chopper system 420 has a semiconductor switch 422 and a resistor 424. Power from the intermediate DC voltage circuit 410 can thus be consumed in the short term by this chopper system 420. The semiconductor switch 422 can be controlled in a pulsed manner for this purpose in order to guide current pulses from the intermediate DC voltage circuit 410 accordingly through the resistor 424. The resistor 424 becomes hot and can thereby consume the supplied power. The control of this chopper system 420 is provided, in particular, for a short-term power removal for grid support. The bidirectional inverter 408 can be controlled accordingly for this purpose in such a way that it removes the power to be consumed from the electrical supply would 404 and the chopper system 420 consumes said power or a proportion thereof as described.

(32) In particular, a central controller 426 is provided to control the charging station 400. This central controller 426 essentially coordinates the corresponding elements of the charging station 400. By way of illustration, internal data transmission lines 428 are provided for this purpose which are denoted here in each case with the same reference number for the sake of simplicity in order to make it clear that this involves internal data transmission lines which transmit data within the charging station 400, i.e., in particular, in both directions, i.e., from the central controller 426 and to the central controller 426. The central controller 426 is thus connected in each case via an internal data transmission line 428 to the bidirectional inverter 408, the battery bank 418, the chopper system 420, each charging pole 414 and the distributor circuit 412.

(33) The central controller 426 can accordingly control, in particular, the charging operation of the charging station 400, such as, if necessary, a charging power allocation for each charging pole 414, for example, and the corresponding removal of electrical power from the supply grid 404. However, the battery bank 418 can also be controlled for buffering and the power allocation can also be performed via a controller of the distributor circuit 412. Controllers of this type can, in particular, be combined. Additional data transmission lines can furthermore also be provided, such as, for example, between the charging poles 414 and the distributor circuit 412. Data transmission of this type can also be performed centrally via the central controller 426. However, other data network topologies for the communication within the charging station 400 are also conceivable.

(34) However, it is proposed, in particular, that the central controller 426 controls the bidirectional inverter 408 in order to control a grid support if necessary as a result. Depending on the type of grid support, a corresponding control or control adaptation may be required within the charging station 400. It may be necessary, for example, to control the battery bank 418 if the bidirectional inverter 408 is intended to feed active power into the grid 404. If the power which is to be removed from the grid 404 is specified, a control of the chopper system 420 may possibly be required. An adapted control of the charging procedures of the electric vehicles 416 which are connected to the charging poles is also conceivable.

(35) An external data transmission line 430 is furthermore provided in order to be able to take account of direct specifications by a grid operator also. An external data transmission line 430 of this type is shown here to a grid controller 432. However, this grid controller 432 can also represent a grid operator which operates the electrical supply grid 404. A grid operator of this type or the grid controller 432 can, for example, request an active power feed-in. In order to control this or further operations, the central controller 426 of the charging station 400 can also supply information concerning the external data transmission line 430 to the grid controller 432, indicating how much power capacity the charging station 400 and therefore the battery bank 418 in particular, actually has available. However, the grid controller 432 can, for example, also specify limit values. Such limit values may, for example, mean a maximum active power removal for the charging station 400, or a gradient limitation for the maximum change in an active power removal, to mention but two examples.

(36) FIG. 4 furthermore illustrates a power station 434 which is connected via a power station transformer 436 to the electrical supply grid 404. By way of precaution, it should be noted that further transformers 438 can also be provided, but these are not relevant here. A further transformer 438 of this type is shown merely for illustration in order to make it clear that different voltage levels can also exist in the electrical supply grid 404.

(37) In any case, the power station 434 can be provided as a conventional power station, such as, for example, a coal-fired power station or a nuclear power station. By way of illustration, a windfarm 440 is furthermore shown which is connected via a windfarm transformer 442 to the electrical supply grid 404. Both the conventional power station 434 and the windfarm 440 could similarly communicate via external data transmission lines 430 with the grid controller 432. It is furthermore provided for the windfarm 440 that said windfarm can communicate or exchange data directly with the central controller 426 and therefore with the charging station 400.

(38) FIG. 4 is intended to illustrate, in particular, that the windfarm 440 and the charging station 400 are disposed essentially close to one another in the electrical supply grid 404. They also disposed on a grid section having the same voltage level. A correspondingly long distance to the power station 434 is also intended to be illustrated by corresponding dots between the further transformer 438 and the power station transformer 436.

(39) The windfarm 440 is therefore disposed comparatively close to the charging station 400, in any case in relation to the connection between the charging station and the windfarm via a section of the electrical supply grid 404. This section is indicated here as the connection section 444 and designates the area between the windfarm transformer 442 and the grid transformer 406 of the charging station 400. However, a connection section of this type does not have to be provided as an immediate and direct connection line, but may also include further branches to other consumers or local feeders.

(40) In any case, the charging station 400 and the windfarm 440 are so close to one another that the windfarm 440 can influence the voltage at the grid connection point 402 of the charging station 400. The charging station 400 can equally influence a voltage on the windfarm transformer 442.

(41) With the knowledge of this proximity between the windfarm 440 and the charging station 400, it is now proposed that they are coordinated with one another, particularly in terms of a grid support. To do this, a communication between the windfarm 440 and the charging station 400 is provided which is illustrated here by an external data transmission line 430 to the central controller 426. A coordination of this type can also relate to the implementation of a request from a grid operator by the grid controller 432. If, for example, the grid operator thereby specifies a request for an active power reduction in the electrical supply grid 404, this active power reduction can be coordinated in such a way that the windfarm 440 feeds in a lesser proportion, for example half, thereof, and the charging station 400 removes an additional proportion, for example the remaining half, thereof.

(42) However, a coordination is also conceivable for other tasks, such as, for example, a voltage regulation by means of reactive power feed-in. It can be provided here, in particular, that both the windfarm 440 and the charging station 400 perform a part of the required reactive power feed-in. This can offer the advantage that neither of the two, i.e., neither the windfarm 440 nor the charging station 400, has to control a very wide phase angle, which can be inefficient, but they can instead be divided so that they both feed in a part of the reactive power and in each case do not therefore have to control an excessively wide phase angle.