METHOD FOR DETERMINING THE ENERGY PRODUCTION OF A WIND POWER INSTALLATION

Abstract

The invention relates to a method for determining the energy production to be expected for a wind power installation for a forecast time period, which may be an expected annual energy production. The installation has installation components. In the method, at least one of the installation components is selected as a thermally relevant component and chronologically distributed wind speed values are specified for the forecast time period. An expected power output level of the installation is determined for one of the wind speed values. In the power output level determining step, a component temperature which is assigned to this wind speed value is taken into account by the at least one thermally relevant component. The expected power output level of the installation, which is determined for the wind speed value, is used to determine the energy production of the installation which is to be expected for the forecast time period.

Claims

1. A method for determining energy production expected from a wind power installation for a forecast time period, comprising: selecting at least one component of a plurality of components of the wind power installation as a thermally-relevant component; specifying a plurality of chronologically distributed wind speed values for the forecast time period; determining an expected power output level of the wind power installation for a wind speed value of the plurality of wind speed values depending on a component temperature of the thermally-relevant component assigned for the wind speed value, the expected power output level being an installation power output level expected to be generated by the wind power installation for the wind speed value; and determining the energy production of the wind power installation expected for the forecast time period based on the expected power output level of the wind power installation determined for the wind speed value.

2. The method as claimed in claim 1, wherein the energy production expected from the wind power installation for the forecast time period is an expected annual energy production of the wind power installation.

3. The method as claimed in claim 1, comprising: specifying a plurality of chronologically distributed outside temperature values respectively assigned to one of the plurality of wind speed values; and determining the expected power output level for the wind speed value using an outside temperature value of the plurality of outside temperature values assigned to the wind speed value and the component temperature of the thermally-relevant component assigned to the wind speed value.

4. The method as claimed in claim 1, wherein determining the energy production expected for the forecast time period includes: repeating determining the expected power output level successively for all wind speed values of the plurality of wind speed values to obtain a plurality of expected power output levels; obtaining the component temperature of the thermally-relevant component respectively assigned to a corresponding wind speed value of the plurality of wind speed values and determining a respective expected power output level based on the component temperature respectively assigned to the corresponding wind speed value; and determining the energy production of the wind power installation expected for the forecast time period based on the plurality of expected power output levels.

5. The method as claimed in claim 1, comprising: determining, for the wind speed value, a power output level that the wind power installation is capable of generating under ideal boundary conditions and/or without accounting for thermal losses; and determining the expected power output level from the power output level that the wind power installation is capable of generating using an adaptation rule assigned to the wind speed value.

6. The method as claimed in claim 5, wherein the adaptation rule specifies a temperature-dependent power upper limit to which the power output level that the wind power installation is capable of generating is limited such that the power output level that the wind power installation is capable of generating as limited to the temperature-dependent power upper limit forms the expected power output level.

7. The method as claimed in claim 1, comprising: determining an expected energy production loss that is thermally conditioned and assigned to the wind speed value from a power output level that the wind power installation is capable of generating under ideal boundary conditions or both the power output level that the wind power installation is capable of generating under ideal boundary conditions and the expected power output level.

8. The method as claimed in claim 1, comprising: determining the component temperature of the thermally-relevant component based on a thermal capacity and/or at least a thermal resistance of the thermally-relevant component.

9. The method as claimed in claim 8, comprising: determining the component temperature of the thermally-relevant component based on an outside temperature and/or the thermal capacity.

10. The method as claimed in claim 1, comprising: specifying a plurality of temperature-dependent downward control rules for a plurality of thermally-relevant components of the wind power installation, respectively, wherein each temperature-dependent downward control rule of plurality of temperature-dependent downward control rules respectively simulates a rule for performing downward control of the wind power installation that is dependent on the component temperature of the respective thermally-relevant component.

11. The method as claimed in claim 1, comprising: obtaining at least one adaptation rule for performing downward control of the wind power installation based on the component temperature.

12. The method as claimed in claim 11, wherein obtaining the at least one adaptation rule for performing downward control of the wind power installation based on the component temperature includes obtaining the at least one adaptation rule based on a plurality of downward control rules.

13. The method as claimed in claim 1, wherein: determining a plurality of expected power output levels of the wind power installation for the plurality of wind speed values in chronological succession such that a current output level determining has a preceding power output level determining, an adaptation rule obtained in the preceding power output level determining or depending on the preceding power output level determining is used in the current power output level determining to obtain a power output level that the wind power installation is capable of generating under ideal boundary conditions for a current wind speed value, and an expected power output level is obtained based on the power output level that the wind power installation is capable of generating under ideal boundary conditions for the current wind speed value and using the adaptation rule obtained in the preceding power output level determining.

14. The method as claimed in claim 1, comprising: determining that downward control of the wind power installation is to be performed for a plurality of thermally-relevant components, wherein a downward control amount that causes a greatest downward control of a thermally-relevant component of the wind power installation is controlling.

15. The method as claimed in claim 1, wherein the thermally-relevant component is selected from a group of installation components which include at least: a generator, a stator of the generator, a rotor of the generator, and a tower formed at least partially from steel.

16. The method as claimed in claim 1, wherein: the thermally-relevant component is provided with an active cooling system, and determining the component temperature of the thermally-relevant component is based on a behavior of the active cooling system.

17. The method as claimed in claim 16, comprising: determining the energy production expected for the forecast time period at least once for active cooling and at least once without active cooling;, wherein the active cooling system is taken into account in determining the energy production expected for the forecast time period for active cooling, the active cooling system is not taken into account in determining the energy production expected for the forecast time period without active cooling.

18. The method as claimed in claim 17, comprising: comparing the energy production expected for the forecast time period determined for active cooling and the energy production expected for the forecast time period determined without active cooling.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0078] The invention will now be explained in more detail on the basis of preferred exemplary embodiments and with reference to the figures, of which:

[0079] FIG. 1: shows a wind power installation which has a plurality of installation components;

[0080] FIG. 2: shows a flow diagram of a method for determining the expected energy production level;

[0081] FIG. 3: shows a flow diagram of a power output level determining step;

[0082] FIG. 4: shows two derating curves of a wind power installation with a cooling package option;

[0083] FIG. 5: shows a component temperature profile of a generator;

[0084] FIG. 6: shows a schematic view of a wind power installation and of a cut-open nacelle; and

[0085] FIG. 7: shows a derating curve of a wind power installation with an option for a warm climate.

DETAILED DESCRIPTION

[0086] FIG. 1 shows a schematic view of a wind power installation 100 according to one embodiment.

[0087] The wind power installation 100 has for this purpose a tower 102 and a nacelle 104. An aerodynamic rotor 106 with three rotor blades 108 and a spinner 110 is arranged on the nacelle 104. The rotor 106 is made to move in rotation by the wind during operation and as a result drives a generator in the nacelle 104.

[0088] The generator is connected to an electrical power grid, for example a wind farm power grid or an electrical supply power grid, by means of an inverter, in order to feed in a three-phase oscillating current.

[0089] The wind power installation comprises for this a control circuit and/or a controller and/or an inverter and/or a controller of an inverter which is configured to execute a method as described above or below.

[0090] FIG. 2 shows a flow diagram of a method for determining the expected energy production level of a wind power installation within a forecast time period. The wind power installation has a plurality of installation components. At least one of the installation components is selected as a thermally relevant component (step Si) according to a predefined criterion, in particular in dependence on the ratio of the external thermal resistance of an installation component to its internal thermal resistance. In the method a plurality of chronologically distributed wind speed values are also specified for the forecast time period (step S2). The specified wind speed values can be wind speed values of a wind speed profile. In the method, a plurality of outside temperature values which are chronologically distributed over the forecast time period and are respectively assigned to one of the specified wind speed values are also specified (step S3). However, in alternative variants of the method no outside temperature values are specified and are therefore not taken into account in obtaining an expected power output level for a wind speed value.

[0091] In the method, in order to determine the expected energy production level over the forecast time period, a power output level determining step LB is respectively carried out successively for all the specified wind speed values. Each of the power output level determining steps LB can be carried out as described with respect to FIG. 3.

[0092] In particular, in each of the power output level determining steps LB an expected power output level, assigned to one of the specified wind speed values, of the wind power installation is determined for this wind speed value. In order to determine the expected power output level for one of the wind speed values, an ideal power output level is firstly determined on the basis of a power output curve of the wind power installation (step S4). The expected power output level is obtained from the ideal power output level by means of an adaptation rule which is assigned to the wind speed value and has been obtained in one of the preceding power output level determining steps (step S5). The adaptation rule stipulates in particular the downward control amount or downward control proportion of the installation power output level of the wind power installation by which a reduction will be implemented in the next step or pass. In particular, the adaptation rule specifies a temperature-dependent power upper limit to which the ideal power output level is to be limited, so that the ideal power output level which is limited to the power upper limit forms the expected power output level provided that the ideal power output level is not already below it.

[0093] The adaptation rule is obtained in particular in dependence on the component temperature of at least one thermally relevant component. In particular, in a power output level determining step for a wind speed value a component temperature of at least one thermally relevant component is obtained individually for this component. The adaptation rule is then obtained by means of a downward control rule which is specified for this thermally relevant component, and by means of the determined component temperature, and assigned to a chronologically subsequent wind speed value. The adaptation rule then stipulates the downward control amount or downward control proportion by which the ideal power output level determined for the subsequent wind speed value is to be reduced. For example, the downward control rule can specify a maximum permissible temperature upper limit for a component. If the component temperature which is obtained for this component is above the temperature upper limit, the adaptation rule in particular is obtained in such a way that the installation power output level is reduced by a downward control amount which is selected in such a way that the component temperature drops below the temperature upper limit again.

[0094] In the method, the component temperature of at least one thermally relevant component is obtained in dependence on the thermal capacity of the components by means of a thermally transient model. By using a thermally transient model of the component, the component temperature can be determined in particular in dependence on the intrinsic properties such as the geometry and the thermal capacity of the component. Comparatively inaccurate estimation of the component temperature on the basis of an outside temperature value can be avoided in this way.

[0095] However, in order to determine the expected power output level for a wind speed value it is possible to use, in addition to the component temperatures which are assigned to this wind speed value, also the outside temperature value which is assigned to this wind speed value, in order to make the calculation of the component temperatures even closer to reality.

[0096] A theoretically possible energy production level is calculated from the ideal power output level determined in a power output level determining step LB for a wind speed value, and an expected energy production level is calculated from the expected power output level determined in this power output level determining step LB, by multiplying the ideal power output level and the expected power output level by a time period (step S6). The respective time period is respectively selected for each of the wind speed values in such a way that it encompasses the time period up to the chronologically subsequent wind speed value. In this way, each of the specified wind speed values and expected energy production levels which is assigned to this wind speed value is respectively calculated.

[0097] In order to determine the energy production level which is expected for the forecast time period, the expected energy production levels which are assigned to the wind speed values are summed (step S7).

[0098] Alternatively or additionally, an energy production loss which is expected for the forecast time period can also be determined by obtaining a theoretically possible energy production level and an expected energy production level for each of the wind speed values and forming the difference between them. The difference then corresponds to the energy production loss for this wind speed value. A respectively assigned expected energy production loss can therefore be determined for each of the wind speed values, and the plurality of energy production losses which are determined in this way can be summed, in order therefore to calculate the energy production loss which is expected for the forecast time period.

[0099] FIG. 3 shows a flow diagram of a power output level determining step in which an expected power output level of a wind power installation with a plurality of installation components is obtained for a wind speed value, and an adaptation rule which is assigned to a chronologically subsequent wind speed value is obtained.

[0100] Before the power output level determining step is executed, a plurality of chronologically distributed wind speed values are specified (step Inl) and a power output curve of the wind power installation is obtained (step In2). The time stamps of the specified wind speed values are in particular within a forecast time period for which an expected energy production level of a wind power installation is to be determined.

[0101] The specified wind speed values can be wind speed values of a wind speed profile. The same wind speed profile can be used to obtain the power output curve of the wind power installation.

[0102] The power output level determining step for one of these specified wind speed values is executed, but can be repeated successively for all the further specified wind speed values.

[0103] In the power output level determining step, an ideal power output level of the wind power installation is firstly obtained on the basis of the power output curve for the wind speed value (step L1). An expected power output level is obtained from the ideal power output level by means of an adaptation rule which is assigned to the wind speed value (step L2). The adaptation rule has been obtained chronologically before the power output level determining step (step In3) and assigned to this wind speed value. The adaptation rule specifies a temperature-dependent power upper limit to which the ideal power output level is reduced. The reduced installation power output level is then the expected power output level. In particular, the adaptation rule which is assigned to the wind speed value has been obtained in a preceding power output level determining step which was executed for a chronologically earlier wind speed value. In particular, in the preceding power output level determining step a component temperature of at least one thermally relevant component was modeled and compared with a temperature upper limit specified for the component, and the adaptation rule assigned to the wind speed value was obtained on the basis of the comparison.

[0104] If the power output level determining step is executed as the first power output level determining step and there is correspondingly no preceding power output level determining step, the adaptation rule can be specified with the value 1, so that for this power output level determining step the ideal power output level corresponds to the expected power output level. Alternatively, a value can be assumed on the basis of a steady-state behavior. It is also taken into consideration that the first step, or a plurality of first steps, is/are not included in the actual determination of the expected energy production level and do not serve only for the transient oscillation of the process.

[0105] The expected power output level can be converted into an energy production level which is expected for a specific time period by multiplying said energy production level by a time period. The time period can correspond in particular to the time interval between this wind speed value and a chronologically successive wind speed value of the specified wind speed values. In particular, an energy production level can be respectively obtained for all the specified wind speed values, for the time period up to the wind speed value which is the one which follows next in chronological terms and the obtained energy production levels are summed in order to determine the expected energy production level for a forecast time period. However, it is also possible to assume a time profile of the expected power output levels, and to only integrate later this profile over the forecast time period to form the expected energy production level.

[0106] An energy production loss which is assigned to the wind speed value can also be calculated from the ideal power output level and the expected power output level (step L3) by forming the difference between the ideal power output level and the expected power output level and multiplying it by a specified time period. The ideal power output level and expected power output level can also be firstly converted into energy levels and then the difference is formed in order to determine the energy production loss which is assigned to the wind speed value. If an energy production loss is respectively determined for a plurality of wind speed values this plurality of energy production losses can be summed or integrated in order to determine an expected energy production loss for the forecast time period.

[0107] Then, an adaptation rule for a chronologically subsequent wind speed value is obtained in the power output level determining step. In order to obtain the adaptation rule, the installation components of the wind power installation are firstly considered.

[0108] A thermally relevant component is selected from the installation components on the basis of a specified criterion. The criterion can be specified in such a way that installation components whose internal thermal resistance is negligible in comparison with their external resistance are thermally relevant components.

[0109] For the at least one thermally relevant component, an individual component temperature of the component is obtained by means of a thermally transient model, in particular by means of the LTC model and taking into account the thermal capacity of the component (step L4). For the other installation components, a component temperature is obtained by means of a steady-state model on the assumption that a change in temperature of the installation component takes place without a delay (step L5).

[0110] An adaptation rule for a chronologically subsequent wind speed value is obtained for each of the installation components in dependence on the respectively obtained component temperatures and downward control rules which are respectively assigned to the installation components.

[0111] The downward control rules of the installation components respectively specify a maximum permissible temperature upper limit for their assigned installation component. The obtained component temperatures of the installation components are respectively compared with the temperature upper limit assigned to the respective installation component (step L6).

[0112] On the basis of the respective comparisons it is determined for each installation component whether the respective temperature upper limit has been exceeded (step L7) or not (step L8). If the component temperatures of a plurality of installation components have exceeded the associated temperature upper limit the downward control amount or downward control proportion by which the wind power installation has to be downward controlled is also detected so that the component temperatures are below their temperature upper limit again.

[0113] In particular the downward control amount of that thermally relevant component which brings about excessive downward control of the wind power installation is then decisive for obtaining the adaptation rule (step L9).

[0114] FIG. 4 shows two derating curves of a wind power installation, respectively with an option for a cold climate (cold climate) and without such an option (normal climate): a first derating curve 401 is for a cold climate, and a second derating curve 402 is for a normal climate.

[0115] The derating curves 401, 402 respectively describe the maximum permissible installation power output level of the wind power installation in dependence on the outside temperature.

[0116] Significant differences can be discerned between the two derating curves 401, 402 in particular in the temperature range between −40° C. and −20° C. These different derating curves 401, 402 can be taken into account in the determination of the expected power output level.

[0117] FIG. 5 shows a component temperature profile of a generator, calculated once with a thermally transient model and calculated once with a steady-state model. A constant outside temperature of 20° C. has been assumed for both simulations, and this is illustrated by the first curve 501.

[0118] The component temperature of the generator, simulated with the steady-state model, is constant at one value over the entire duration of the simulation. This profile is shown by the third curve 503.

[0119] The component temperature profile of the generator, which is simulated with the thermally transient model, exhibits a dynamic behavior. The profile is represented by the second curve 502. At the start of the simulation, the component temperature of the generator rises continuously starting from the value of the outside temperature. As the simulated time period continues, the component temperature of the generator approaches the value of the component temperature which is calculated with the steady-state model. Starting from a simulated time period of approximately ten hours, both models essentially supply the same result for the component temperature of the generator.

[0120] In particular, during the simulated time period of the first ten hours the component temperature of the generator is overestimated as a result of the use of the steady-state model. It has been recognized here that the chronologically thermal behavior of the generator can also be quite significant—as can be recognized from the large time constant according to FIG. 5—and can also be for other components.

[0121] FIG. 6 illustrates installation components which are relevant for a thermal consideration, specifically in one detail of a partially cut-away nacelle 601, a spinner 602 which forms the part of the nacelle 601 facing the wind, and a machine housing 603 which forms the part of the nacelle facing away from the wind. These two components can be taken into account by means of a steady-state model. Furthermore, a stator 604 and a rotor 605, which together essentially form a generator, are shown. The stator 604 and rotor 605 or the generator each have a thermal behavior for which it is proposed that it should be respectively taken into account by means of a dynamic model, in particular an LTC model.

[0122] FIG. 6 also shows schematically a wind power installation 606 which has the nacelle 601 which is arranged on a tower 607, but in a non-sectional illustration. In the tower 607 there is an electric module 608, also in particular an inverter device which usually has a large number of inverters. The electric module 608 is illustrated on the outside only for the purpose of illustration. However, it is usually arranged in the tower, specifically at the tower base there and its thermal behavior can depend on the tower 607 and the method of cooling the electric module.

[0123] FIG. 7 shows a derating curve 701 of a wind power installation with an option for a hot climate (hot climate). A derating curve of a wind power installation without such an option, the derating curve 702, already exhibits a power reduction at a relatively low temperature.

[0124] The derating curves of FIG. 7 show how such different cooling options have previously been taken into account in predictions for their determination of expected power output levels. However, it has been recognized that an option for a hot climate (hot climate) can have a different cooling concept.

[0125] Air cooling, which brings about heating of the air in the tower, is frequently used particularly for the electric module, that is to say particularly for the inverters which are arranged in the tower base. According to a normal option, the tower wall is used for re-cooling the air which has been heated in this way. For this purpose, the air rises in the interior of the tower and cools on the tower wall. Contact with outside air, which may be contaminated, is avoided. It has been recognized that the thermal dynamics of the tower can play a role here and they are therefore taken into account in the determination of the expected energy production level.

[0126] In the option for a hot climate (hot climate) it is assumed that the cooling effect by means of the tower wall is not sufficient because the tower does not cool down sufficiently and instead the heated air is replaced with cooler outside air. The tower wall is therefore not used, or not used exclusively, for cooling. Here, the thermal dynamics of the tower wall can therefore be ignored. This option can also be referred to as an active cooling system, whereas the cooling by means of the tower wall can be referred to as a passive cooling system. In order to check which of the two options provides a better yield, the method for determining an expected energy production level can be made independent for the two options and the results can be compared.

[0127] In another cooling concept, in particular for the electric module, that is to say particularly for the inverters which are arranged in the tower base, a water cooling system with a heat exchanger located outside the tower can be provided. This can be provided for both options, that is to say both for the option for a hot climate (hot climate) as well as for the normal option, wherein the options can then differ in their configuration, that is to say in particular in respect of the magnitude of the cooling flow and the size of the heat exchanger. This cooling concept can also be referred to as an active cooling system, and the thermal dynamics can also be ignored here.

[0128] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.