METHOD FOR OPERATING AN ELECTRICAL STORAGE STATION

Abstract

Provided is a method for operating an electrical storage station on an electrical supply network. The network has electrical consumers, the storage station, and at least one wind power installation to generate electrical power from wind. The method includes generating electrical power by way of the installation as generated wind power, and feeding a feed-in power into the network. The electrical feed-in power at least results from the generated wind power and a storage power taken up or output by the storage station. The feeding of the feed-in power into the network is controlled depending on a station state of charge and a wind and/or power forecast. Changes in the feed-in power over time are controlled depending on the wind and/or power forecast and a limit gradient is specified to limit the changes in the feed-in power thereto. The limit gradient is specified depending on the wind and/or power forecast.

Claims

1. A method for operating an electrical storage station in an electrical supply network, wherein the electrical supply network includes: electrical consumers; the electrical storage station configured to draw and output electrical storage power; and at least one wind power installation configured to generate electrical power from wind, and the method comprises: generating the electrical power using the at least one wind power installation as generated wind power; and feeding a feed-in power into the electrical supply network, wherein: the feed-in power is an aggregate of the generated wind power and a storage power drawn by or output from the electrical storage station, the feeding of the feed-in power into the electrical supply network is controlled depending on: a state of charge of the electrical storage station, and a wind forecast and/or a power forecast, changes in the feed-in power over time are controlled depending on the wind forecast and/or the power forecast, at least one limit gradient is set for the changes in the feed-in power to limit the changes in the feed-in power to the at least one limit gradient, and the at least one limit gradient is set depending on the wind forecast and/or the power forecast.

2. The method as claimed in claim 1, comprising: counting a charging of the electrical storage station and/or a discharging of the electrical storage station as a charging cycle; and controlling the electrical storage station and/or the feeding of the feed-in power depending on the counted charging cycles.

3. The method as claimed in claim 1, that, wherein: the power forecast is a prediction of an expected power or an expected power profile that the at least one wind power installation feeds into the electrical supply network in a prediction period, the wind forecast is a prediction of an expected wind speed or an expected wind speed profile at the at least one wind power installation or a wind farm in a forecast period, and the power forecast and/or the wind forecast is determined or adjusted depending on recorded values, wherein the recorded values are selected from a list including: an installation power that is output by the at least one wind power installation, a wind farm power that is output by the wind farm when the at least one wind power installation is operated with other wind power installations in the wind farm, a wind speed measured by the at least one wind power installation, in a region of the at least one wind power installation or in the wind farm, a rotational speed of the at least one wind power installation, a blade angle of at least one rotor blade of the at least one wind power installation, and an installation availability of the at least one wind power installation.

4. The method as claimed in claim 3, comprising: recording a respective time profile and/or a respective sequence for one or more of the recorded values.

5. The method as claimed claim 1, comprising: determining the wind forecast and/or the power forecast depending on a weather forecast obtained received from an external weather service; and adjusting the wind forecast and/or the power forecast depending on a local adjustment rule determined based on at least one locally recorded value.

6. The method as claimed in claim 1, wherein: a plurality of prediction models are used to determine the wind forecast or the power forecast, wherein the plurality of prediction models includes at least one current model to be used and a reference model for adjusting the current model, the current model is trained using a learning phase, and a first model deviation representing a deviation between forecasts of the current model and the reference model is recorded, the current model is applied in an application phase, and a second model deviation representing a deviation between the forecasts of the current model and the reference model is recorded, the second model deviation of the application phase is compared with the first model deviation of the learning phase, and the current model is changed to decrease a magnitude of the second model deviation of the application phase in response to the magnitude of the second model deviation of the application phase being greater than a magnitude of first model deviation of the learning phase.

7. The method as claimed in claim 1, comprising: determining a feed-in schedule for use by a network operator, wherein the feed-in schedule specifies a feed-in of electrical power into the electrical supply network over a planning period, and the feed-in schedule is determined depending on: the wind forecast and/or the power forecast, at least one locally recorded value, and the state of charge of the electrical storage station.

8. The method as claimed in claim 1, comprising: determining a forecast quality for the wind forecast and/or the power forecast, wherein the forecast quality for the wind forecast indicates an estimate of an expected deviation of the wind from the wind forecast, and or the forecast quality for the power forecast indicates an estimate of an expected deviation of the generated wind power from the power forecast.

9. The method as claimed in claim 1, wherein: a target state of charge is specified for the electrical storage station, and the target state of charge is specified depending on the wind forecast and/or the power forecast.

10. A wind power system for feeding a feed-in power into an electrical supply network having a plurality of electrical consumers, the wind power system comprising: at least one wind power installation configured to generate electrical power from wind, wherein the at least one wind power installation includes an inverter configured to output the electrical power generated from the wind as generated wind power; an electrical storage station configured to draw and output electrical storage power, and wherein the wind power system is configured to feed the feed-in power into the electrical supply network, wherein the feed-in power is an aggregate of the generated wind power and a storage power drawn from or output by the electrical storage station; and a controller configured to control feeding the feed-in power into the electrical supply network depending on: a state of charge of the electrical storage station, and a wind forecast and/or a power forecast, wherein: changes in the feed-in power over time are controlled depending on the wind forecast and/or the power forecast, at least one limit gradient is set for the changes in the feed-in power to limit the changes in the feed-in power to the at least one limit gradient, and the at least one limit gradient is set depending on the wind forecast and/or the power forecast.

11. The wind power system as claimed in claim 10, wherein the controller is coupled by a communication link to: the at least one wind power installation, the electrical storage station, and a control center of the electrical supply network.

12. The wind power system as claimed in claim 10, comprising: a communication interface configured to receive at least one weather forecast for evaluation by the controller.

13. The method as claimed in claim 2, comprising: setting the at least one limit gradient depending on the counted charging cycles.

14. The method as claimed in claim 2, comprising: determining a cycle forecast depending on the power forecast, wherein the cycle forecast indicates a number of the charging cycles to be expected within a service life of the electrical storage station; and controlling the electrical storage station and/or the feeding of the feed-in power depending on the cycle forecast.

15. The method as claimed in claim 6, wherein the current model has a higher order than the reference model.

16. The method as claimed in claim 7, comprising: determining the feed-in schedule depending on the at least one limit gradient.

17. The method as claimed in claim 8, comprising: setting the changes in the feed-in power over time depending on the forecast quality; and/or determining a feed-in schedule depending on the forecast quality.

18. The method as claimed in claim 8, comprising: setting the at least one limit gradient depending on the forecast quality.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0084] The invention is now explained in more detail below by way of example based on embodiments with reference to the accompanying figures.

[0085] FIG. 1 shows a perspective view of a wind power installation.

[0086] FIG. 2 shows a schematic view of a wind power system comprising a wind farm and a storage station.

[0087] FIG. 3 shows a controlling structure for controlling and thus operating an electrical storage station.

DETAILED DESCRIPTION

[0088] FIG. 1 shows a wind power installation 100 comprising an output unit 101, which can be designed as an inverter, a tower 102 and a nacelle 104. A rotor 106 having three rotor blades 108 and having a spinner 110 is provided on the nacelle 104. During operation, the rotor 106 is set in rotational motion by the wind and thereby drives a generator in the nacelle 104.

[0089] FIG. 2 shows a wind farm 112 comprising, for example, three wind power installations 100, which can be the same or different. The three wind power installations 100 are therefore representative of basically any number of wind power installations in a wind farm 112. The wind power installations 100 provide their power, specifically in particular the electricity generated, via an electrical farm network 114. Here, the currents or powers generated in each case by the individual wind power installations 100 are added up and a transformer 116 is usually provided, which can also be referred to as a network transformer and steps up the voltage in the farm in order to then feed into the supply network 120 at the common network connection point 118, which is also synonymously referred to as a point of common coupling (PCC) or feed-in point.

[0090] FIG. 2 is only a simplified illustration of a wind farm 112 which, for example, does not show any control of the wind farm, although such a control is of course present. The farm network 114 can also, for example, be designed differently, for example in that a transformer is also present at the output of each wind power installation 100, just to name another exemplary embodiment.

[0091] In addition to the wind farm 112, FIG. 2 also shows a storage station (e.g, battery) 200. The storage station 200 can also be connected to the farm network 114 and can then feed into the electrical supply network 120 via said farm network and via the transformer 116 and the common network connection point 118. As an alternative, it is also possible for the storage station 200 to feed into the electrical supply network 120 via its own network connection point 218. For this purpose, the storage station has an inverter 201 that operates bidirectionally. A transformer such as the transformer 116 can also be provided for feeding into the electrical supply network 120 via its own network connection point 218.

[0092] The feed-in of electrical power through the storage station 200 also includes negative feed-in, that is to say the withdrawal of power from the electrical supply network and thus the feed-in of this electrical power in the storage station 200. For the storage station 200, a storage power that is output, which is thus fed into the electrical supply network, is preferably regarded as positive power. Since storage power P.sub.S can thus be taken up or output, this is shown in FIG. 2 by a corresponding double arrow.

[0093] The wind farm 112 thus forms a wind power system 202 together with the storage station 200. A common control device (e.g., controller) 203 is provided for this purpose, which is coupled to the storage station 200, the wind power installations 100 and a control center (e.g., external controller or operator controller) 212 via a communication link (e.g., data line) 205. The control device 203 can also be coupled to a farm controller, which is not shown here, instead of to the wind power installations 100, or in addition thereto.

[0094] FIG. 3 shows a controlling structure (e.g., controller) 300, which essentially serves to control and thereby to operate the storage station 200. Although the storage station 200 is shown somewhat differently to that shown in FIG. 2, it may correspond thereto. The more detailed illustration of the storage station 200 in FIG. 3 serves only to better explain the control relationships. FIG. 3 also shows an industrial consumer 320 and a locality 322 schematically and representative of other consumers as two possible consumers on the electrical supply network for illustration purposes.

[0095] Otherwise, a wind power installation 100 is also indicated in the controlling structure 300, which wind power installation can thus correspond to the wind power installation 100 in FIG. 1 or to a respective wind power installation 100 in FIG. 2. Otherwise, however, the wind power installation 100 in FIG. 3 is also representative of a plurality of wind power installations or else a wind farm 112 according to FIG. 2. Both the wind power installation 100 and the storage station 200 feed power into the electrical supply network 120 and this can be done via the common network connection point 118. Any network transformer such as the network transformer 116 of FIG. 2 can also be provided, but for the sake of simplicity it is not illustrated here.

[0096] In addition, the controlling structure 300 uses a weather station 302, which is shown in FIG. 3 but only supplies information, specifically a wind forecast WP in particular. The weather station 302 can in this case be located somewhere else and the transmission of information, specifically the transmission of the wind forecast WP in particular, can also take place wirelessly. The weather station 302 is not part of the wind power system 300. Only one communication interface to the weather station 302 can be part of the wind power system 300.

[0097] During operation, the wind power installation 100 feeds in a wind power P.sub.W. In addition, the storage station 200 feeds a storage power P.sub.S, which can also be negative if the storage station takes up this storage power P.sub.S. Both together result in the feed-in power P.sub.F, which thus results as the sum of the wind power P.sub.W and the storage power P.sub.S:

P.sub.F=P.sub.W+P.sub.S

[0098] Ideally, the wind power installation 100 feeds in as much wind power P.sub.W as is possible due to the prevailing wind. The storage station 200 then adapts to this and feeds in storage power accordingly, that is to say outputs storage power or takes up storage power, in order thereby to stabilize the feed-in power P.sub.F.

[0099] It is pointed out that the wind power P.sub.W, the storage power P.sub.S and the feed-in power P.sub.F actually denote powers in the controlling structure 300 insofar as they are marked with a separate arrow on lines which are also marked as three-phase lines in the controlling structure 300. The remaining connecting lines of the controlling structure 300 only indicate signal lines or data lines on which measured values, setpoint values or other information are transmitted in particular.

[0100] The storage station 200 thus obtains a storage power setpoint value P.sub.SS, which gives the storage station 200 the information about the level of storage power P.sub.S to be output or taken up.

[0101] The storage power setpoint value P.sub.SS depends here on a feed-in power setpoint value P.sub.FS and the wind power P.sub.W. The wind power P.sub.W is recorded for this purpose, for example, in the power measurement unit (e.g., power meter or Watt meter) 304 and provided to the summing element 306 as the measured wind power value P.sub.WM and there is drawn from the feed-in power setpoint value P.sub.FS.

[0102] The feed-in power setpoint value P.sub.FS is determined and output by the feed-in planning block 308. According to the controlling structure 300, the feed-in power setpoint value P.sub.FS(t) is indicated as output variable of the feed-in planning block 308. This should make it clear that this feed-in power setpoint value P.sub.FS(t) can be a variable that changes over time and can in particular also be output as a time profile. The same can then of course also apply to the other variables, in particular to the storage power setpoint value P.sub.SS that is calculated from this. For the sake of clarity, the possible time dependency is not indicated for the other variables, although it can exist.

[0103] The feed-in planning block 308 determines the feed-in power setpoint value P.sub.FS depending on the measured wind power value P.sub.WM, depending on at least one limit gradient G.sub.max, depending on a state of charge SC of the storage station 200 and depending on a power forecast PP or instead of the power forecast PP or additionally depending on a wind forecast WP. The state of charge SC as well as the wind forecast WP or the power forecast PP can be included in this case indirectly via the limit gradient G.sub.max.

[0104] The limit gradient G.sub.max is determined in the gradient block 310. The limit gradient G.sub.max is also drawn as representative of a plurality of limit gradients. In particular, an upper limit gradient, which thus limits an increase in power, and a lower limit gradient, which limits a decrease in power, can be provided.

[0105] The at least one limit gradient G.sub.max is determined here depending on the state of charge SC and the wind forecast WP and/or the power forecast PP. In this case, the state of charge SC is particularly taken into account in such a way that, when the state of charge SC is low, the at least one limit gradient G.sub.max is set in particular in such a way that an increase in the feed-in power P.sub.F is limited to a greater extent than a reduction in the feed-in power P.sub.F. In principle, this can lead to the state of charge SC increasing. Accordingly, a reduction in the feed-in power P.sub.F can be limited to a greater extent than an increase when the state of charge SC is high and should be lowered.

[0106] On the other hand, the wind forecast WP can be taken into account in order to be able to anticipate changes in the wind power P.sub.W. A power forecast PP from the wind power installation 100 can also be used directly for this purpose. For this purpose, the wind power installation 100 itself can receive a wind forecast as an input variable. The wind power installation 100 may possibly be best able to derive a power forecast PP from the wind forecast WP due to its own behavior and make it available to the gradient block 310. In any case, a change can be foreseen or at least expected on the basis of a wind forecast, that is to say especially a weather forecast, and depending on this it is possible to assess the range in which limit gradients can be maintained at all.

[0107] It should be noted that the limit gradients relate to the feed-in power P.sub.F. The feed-in power P.sub.F can also be planned in particular by way of one or more limit gradients G.sub.max and such planning can be handed over to a network operator. It is therefore proposed that the ranges that are considered for the limit gradients or at least the one limit gradient G.sub.max are taken into account depending on a wind forecast WP and/or a power forecast PP.

[0108] The at least one limit gradient G.sub.max is determined in this way in the gradient block 310 and passed to the feed-in planning block 308. For example, a positive limit gradient in the sense of a temporally rising edge and a negative limit gradient in the sense of a temporally falling edge can be determined and passed to the feed-in planning block 308. Depending on this, the feed-in power setpoint value P.sub.FS can then be determined taking into account the measured wind power value P.sub.WM, that is to say taking into account the currently fed-in wind power P.sub.W.

[0109] In the ideal case, which also initially serves as an explanation, the wind conditions are stable and the wind power installation 100 feeds in an essentially constant wind power P.sub.W. The wind power hardly changes and this can then immediately form the feed-in power setpoint value P.sub.FS. The measured wind value P.sub.WM is subtracted from this setpoint value at the summing element 306 and the result should then be zero. The storage power setpoint value P.sub.SS would then thus be zero and the storage station would then need neither to output or take up storage power P.sub.S.

[0110] However, if the wind fluctuates so strongly that the wind power P.sub.W and thus also the measured wind power value P.sub.WM exceed the limits according to the limit gradient G.sub.max or the two limit gradients in terms of magnitude, one possibility is that the measured wind power value P.sub.WM is used as feed-in power setpoint value P.sub.FS as long as the measured wind power value P.sub.WM lies within the limits that are specified by the at least one limit gradient G.sub.max. However, if the measured wind power value P.sub.WM reaches the limits specified in this way and if they are exceeded in terms of magnitude, the respective limit value exceeded in terms of magnitude can then be used as the feed-in power setpoint value P.sub.FS. This is output and the measured wind power value P.sub.WM is again subtracted therefrom at the summing element 306. For the values at which the measured wind power value P.sub.WM has exceeded the specified limits in terms of magnitude, these exceedances thus result with the opposite sign as the storage power setpoint value P.sub.SS. This is provided to the storage station 200 and said storage station adjusts the storage power value P.sub.S accordingly and thus compensates for the excessive fluctuations in the wind or wind power P.sub.W via battery power so that the feed-in power P.sub.F stays within the given limits.

[0111] The specification of the at least one limit gradient G.sub.max depending on the state of charge SC can thus influence how greatly the wind power P.sub.W or its measured value P.sub.WM exceeds a positive limit value or falls below a negative limit value at least on average in the short term and can thus specify whether the storage station 200 instead has to compensate for an exceeding power or an undershooting power. Accordingly, the state of charge will decrease or increase, or remain the same. It is therefore proposed to include the state of charge SC when calculating the limit gradient G.sub.max. The wind forecast WP or the power forecast PP is also taken into account because it also depends on whether an upper limit is exceeded or a lower limit is undershot.

[0112] Both the state of charge SC and the wind forecast WP and/or power forecast PP can also be taken into account directly in the feed-in planning block 308. This is considered particularly when the feed-in power P.sub.F should be limited not only to the limits specified by the limit gradient G.sub.max but instead should be guided in a more targeted manner, in particular in a range approximately in the middle of two specified limits or two specified limit gradients. Here, it is considered particularly that the feed-in planning block 308 creates a feed-in schedule, according to which the feed-in power P.sub.F that should be fed in is specifically predicted, particularly for a planning period. Such a planning period as a period can reach from a first time t.sub.1 until a second time t.sub.2. A feed-in schedule can be created for this and output to a network operator so that they can plan better. The output to a network operator can be the output to a control center (e.g., external controller or operator controller) 312. This is indicated in the controlling structure 300 by the fact that the feed-in planning block 308 outputs the feed-in schedule P.sub.F(t.sub.1 . . . 2) and transmits it to the control center 312.

[0113] As a further control option, FIG. 3 also shows that the feed-in planning block 308 determines a target state of charge SCS and takes it into account in the control. This is taken into account in the controlling structure 300 in such a way that this target state of charge SCS is transmitted to the storage station 200. The storage station 200 can take this into account and transmit it to the gradient block 310, for example. The target state of charge SCS can also be transmitted directly to the gradient block 310, which is indicated by dashed lines. The transmission of the target state of charge SCS to the storage station 200 can also achieve a situation in which the target state of charge SCS is directly compared with the state of charge SC. It is then considered that only the difference between the state of charge and the target state of charge is transferred, for example, to the gradient block 310 for further calculation.

[0114] A further possibility for improvement is shown in the controlling structure 300, according to which the gradient block 310 additionally takes into account a number of charging cycles nc that have been carried out. The storage station 200 can determine these charging cycles nc and make them available to the gradient block 310. It is also considered that the charging cycles nc are evaluated in the feed-in planning block 308, which is not shown here only for the sake of clarity.

[0115] In the controlling structure 300, dashed lines indicate that the wind power installation 100 receives a wind forecast WP and outputs a power forecast PP. In addition to installation properties of the wind power installation, which has already been explained above, it is also considered here that the wind power installation 100 compares the wind forecast WP in each case with actual wind values that occur directly at the wind power installation 100. Alternatively, powers can also be compared here if the wind forecast WP is first converted into a power and this is then compared with the actual power at the wind power installation 100. As a result, a deviation between the forecast created by the weather station 302 and local values at the wind power installation 100 can be identified and a system is preferably identified based on a number of such deviations and the wind forecast WP of the weather station 302 is adjusted depending on this system.

[0116] The controlling structure 300 in FIG. 3 also shows that the wind power installation 100 and the storage station 200 feed into the electrical supply network 120 together at the network connection point 118. Although this is a preferred embodiment and is implemented in this way by a proposed wind power system, it is also considered that the storage station is clearly separate from the at least one wind power installation, but feeds it into the same electrical supply network. The power balance is particularly important for the network operator, that is to say to what extent the total power fed in changes. Depending on how greatly the fed-in power changes, the network operator has to or does not have to take countermeasures. Whether the wind power installation 100 or the wind farm 112 is arranged in this case in the immediate vicinity of the storage station 200 and feeds in is of little or no importance to the network operator.

[0117] In addition, particularly the proposed method for operating and thus controlling a storage station can also be implemented if, for example, further wind power installations are added to the electrical supply network 120. The storage station can take this into account without being located in the immediate vicinity of the wind power installations or their feed-in point. The storage station can thus also be operated in the explained sense and thus controlled if a plurality of wind power installations are present and taken into account, but are clearly distributed and feed into the electrical supply network via a plurality of network connection points. The storage station only needs information from these wind power installations to be taken into account. In particular, it requires the total power fed in by all the wind power installations under consideration. This sum of the total power fed in by all the wind power installations under consideration can then be used as the measured wind power value P.sub.WM in the sense of the structure of FIG. 3.

[0118] Likewise, the storage station can be operated and controlled in this sense if a plurality of wind farms are present, which in turn can also be arranged clearly separated from one another and can feed into the electrical supply network via a plurality of network connection points.

[0119] A power forecast for a wind farm based on local measurement data is thus also taken into account. This can include wind farm power, power from wind power installations, measured wind speeds, rotational speeds of wind power installations, blade angles of wind power installations, status information from wind power installations and from wind farms or from the storage station.

[0120] The power forecast can either be calculated centrally for the entire wind farm or calculated by individual wind power installations on an installation-specific basis and then combined in a wind farm controller.

[0121] It is therefore proposed to use the wind forecast and/or a power forecast for one or more of the following applications:

[0122] One application is influencing the state of charge of the storage station, that is to say of an energy store of the storage station, depending on expected power profiles of the wind farm, specifically those predicted by the power forecast. Gradient smoothing can be performed or improved based on this. In particular, it is proposed to preset a lower state of charge when the wind farm is expected to have positive gradients, that is to say when the power of the wind farm is expected to increase, and to correspondingly set a higher state of charge when there are negative gradients.

[0123] A schedule operation with storage support, that is to say with the support of the storage station, is also proposed, especially the creation of a short-term schedule based on a power forecast, and safeguarding the schedule with energy storage. This can optionally be supplemented by updating a longer-term schedule that can be created on the basis of numerical weather forecasts.

[0124] A forecast of the expected charging and discharge cycles of the energy store based on the power forecast for compliance with manufacturer requirements with regard to a lifetime guarantee is also proposed. In particular, an increase in the effectiveness of the energy storage regulation of the storage station is to be achieved. This can be applied in particular to avoid reaching operating limits in the case of long-lasting power gradients if the storage station or its energy store is used for gradient smoothing. Another example is maintaining the service life of the energy store with the best possible utilization of the available charging and discharge cycles.

[0125] Better safeguarding of a schedule operation against long-term or inaccurate wind power forecasts can also be achieved.