METHOD AND WINDFARM CONTROL STAGE FOR CONTROLLING A WINDFARM

Abstract

A method for controlling a windfarm having a plurality of wind power installations and feeding into an electrical supply network at a network connection point is provided. The method includes inputting at least one control error at a control error input of a windfarm control module, generating at least one manipulated variable depending on the at least one control error using at least one controller, and outputting the at least one manipulated variable at a manipulated variable output for transmission to the wind power installations. The method includes recording in each case at least one state of the windfarm, the windpower installations thereof and/or an ambient condition as form state at a state input of the control module, and altering or predefining at least one property of the at least one controller depending on the at least one recorded form state by means of a controller setting device.

Claims

1. A method for controlling a windfarm having a plurality of wind power installations and feeding into an electrical supply network at a network connection point, the method comprising: inputting at least one control error at a control error input of a windfarm control stage, generating, by at least one controller of the windfarm control stage, at least one manipulated variable based on the at least one control error, outputting the at least one manipulated variable at a manipulated variable output for transmission to the plurality of wind power installations, recording, as a form state at a state input of the control stage, at least one state of the windfarm, the plurality of wind power installations or an ambient condition, altering or predefining, by a controller setting device, at least one property of the at least one controller based on the at least one form state.

2. The method as claimed in claim 1, comprising: altering or predefining the at least one property of the at least one controller before a start-up of the windfarm or a wind power installation of the plurality of wind power installations.

3. The method as claimed in claim 1, wherein: the at least one state of the windfarm is at least one state that is recorded from a list of states including: a number of wind power installations installed in the windfarm, rated active power of each wind power installation of the plurality of wind power installations, rated reactive power of each wind power installation of the plurality of wind power installations, number and properties of STATCOM installations in the windfarm, number and properties of battery stores in the windfarm, transmission properties of an internal form network, and active and reactive power relationships or P-Q diagram of each wind power installation of the plurality of wind power installations.

4. The method as claimed in claim 1, wherein the at least one state of the plurality of wind power installations is recorded from a list consisting of the states including: a present availability of active current for feeding-in for each wind power installation of the plurality of wind power installations, a present availability of reactive current for feeding-in for each wind power installation of the plurality of wind power installations, and a present operating state of each wind power installation of the plurality of wind power installations, the present operating state including: presently fed active power, presently feedable active power, presently fed reactive power and presently feedable reactive power.

5. The method as claimed in claim 1, wherein the at least one state of the ambient condition is recorded from a list including: a present wind speed of at least one of the plurality of wind power installations, a present wind direction of at least one of the plurality of wind power installations, a present gustiness of wind of at least one of the plurality of wind power installations, a present air density of the wind of at least one of the plurality of wind power installations, a present air humidity of the wind of at least one of the plurality of wind power installations, and a present temperature of the wind of at least one of the plurality of wind power installations.

6. The method as claimed in claim 1 comprising: altering or predefining a parametrization of the at least one controller based on the at least one recorded form state; and altering or predefining a structure of the at least one controller based on the at least one recorded form state.

7. The method as claimed in claim 1 comprising: altering or predefining a structure of the at least one controller based on a form state of the windfarm; altering or predefining a parametrization of the at least one controller based on a form state of the plurality of wind power installations; and altering or predefining a parametrization or a structure of the at least one controller based on the ambient condition.

8. The method as claimed in claim 6 comprising: selecting between stored controller structures; and altering or predefining the structure of the at least one controller based on the selected controller structure.

9. The method as claimed in claim 1 comprising: determining the at least one control error as a deviation between setpoint and actual values of at least one of the reference variables: network voltage at the network connection point, active power fed at the network connection point, or reactive power fed at the network connection point.

10. A windfarm control stage for controlling a windfarm having a plurality of wind power installations and feeding into an electrical supply network at a network connection point, the windfarm control stage comprising: a control error input configured to receive at least one control error, a manipulated variable output configured to output at least one manipulated variable for transmission to the plurality of wind power installations, at least one controller configured to generate the at least one manipulated variable based on the at least one control error, a state input for recording, as a form state, a state of at least one of: the windfarm, the plurality of wind power installations of the windfarm or an ambient condition, and a controller setting device for altering or predefining at least one property of the at least one controller based on the recorded form state.

11. (canceled)

12. A windfarm control device configured to control a windfarm having a plurality of wind power installations and feed into an electrical supply network at a network connection point, the windfarm control device comprising: a measurement input for recording at least one measurement signal, a setpoint value device for setting at least one setpoint value, a windfarm control stage for generating at least one manipulated value for the wind power installations, a state input for recording, as form state, a state of at least one of the windfarm, the plurality of wind power installations of the windfarm or an ambient condition, and a controller setting device for altering or predefining at least one property of the windfarm control stage based on the recorded form state.

13. The windfarm control device as claimed in claim 12, wherein the windfarm control stage includes: a control error input configured to receive at least one control error, a manipulated variable output configured to output at least one manipulated variable for transmission to the plurality of wind power installations, and at least one controller configured to generate the at least one manipulated variable based on the at least one control error.

14. A windfarm having the windfarm control device as claimed in claim 12 and the plurality of wind power installations.

15. A wind power installation, comprising: a generator, an aerodynamic rotor coupled to the generator, the generator configured to generate electrical power from wind, an inverter configured to generate electric current for feeding into an electrical supply network, a connection configured to electrically connect the inverter to an internal form network of a windfarm to feed the generated electric current into the electrical supply network at a network connection point, and a communication device configured to communicate with a windfarm control stage or a windfarm control device to receive and implement manipulated variables from the windfarm control stage or the windfarm control device, wherein the wind power installation is configured to transmit states of the wind power installation via the communication device to the windfarm control stage or the windfarm control device to enable the windfarm control stage or the windfarm control device to alter at least one property of a controller of the windfarm control module or of the windfarm control device based on the transmitted states.

16. (canceled)

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0071] The invention will now be explained in greater detail by way of example below on the basis of exemplary embodiments with reference to the accompanying figures.

[0072] FIG. 1 shows a wind power installation in a perspective illustration.

[0073] FIG. 2 shows a windfarm in a schematic illustration.

[0074] FIG. 3 shows a control structure in accordance with one embodiment.

[0075] FIG. 4 shows a diagram of a power characteristic, for illustrating the invention.

[0076] FIG. 5 shows a control structure in accordance with a further embodiment.

[0077] FIG. 6 shows by way of example a PI controller in a structure diagram for illustrating parametrization.

[0078] FIG. 7 shows an exemplary structure diagram in accordance with one embodiment for selecting a control structure.

DETAILED DESCRIPTION

[0079] FIG. 1 shows a wind power installation 100 comprising a tower 102 and a nacelle 104. A rotor 106 having three rotor blades 108 and a spinner 110 is arranged on the nacelle 104. The rotor 106 is set in rotation motion by the wind during operation and drives a generator in the nacelle 104 as a result.

[0080] FIG. 2 shows a windfarm 112 comprising for example three wind power installations 100, which can be identical or different. The three wind power installations 100 are thus representative of basically an arbitrary number of wind power installations of a windfarm 112. The wind power installations 100 provide their power, namely in particular the generated current, via an electrical form network 114. In this case, the respectively generated currents or powers of the individual wind power installations 100 are added and a transformer 116 is usually provided, which steps up the voltage in the form in order then to feed it into the supply network 120 at the infeed point 118, which is also generally referred to as PCC. FIG. 2 is merely a simplified illustration of a windfarm 112, which for example does not show a controller, even though a controller is present, of course. Moreover, by way of example, the form network 114 can be configured differently, with for example a transformer also being present at the output of each wind power installation 100, to mention just one different exemplary embodiment.

[0081] FIG. 3 illustrates in the control structure a proposed control set-up of a windfarm 1. The windfarm 1 is substantially formed by the wind power installations 2 and an internal form network 4, which can also comprise network inductors and transformers besides transmission runs. Ultimately, however, the elements of the control structure that are also explained below can also be regarded as part of the windfarm 1. Finally, the form controller is also part of the windfarm 1.

[0082] In any case provision is made for feeding active and reactive power at the network connection point 6 into an electrical supply network 8, which can also be referred to as network for simplification.

[0083] Measurement values at said network connection point 6, in particular a voltage U, fed active power P and fed reactive power Q, can be detected by a measurement device 10. They can be fed to a comparison location 12, at which a setpoint-actual value comparison with a reference variable 14 input there, which is usually also designated by a w, is conducted. The result is the control error 16, which is usually also designated by an e. The reference variable 14 and correspondingly the control error 16 are illustrated here by way of example as one variable, but they can also each concern a plurality of variables; by way of example, two reference variables can be provided, namely one for an active power P to be fed and one for a reactive power Q to be fed.

[0084] The control error 16 is input into a control module or stage 18 comprising at least one controller. For the example of the two reference variables, namely active power P and reactive power Q, two controllers can be contained here. Said controller or said controllers then obtain (in each case) the corresponding control error as input variable and output in each case a manipulated variable 20, which can also be designated by the letter u. For outputting purposes, the control module 18 has an output module or stage 22, which can be configured as a wind power installation data bus and can communicate with a communication module or stage 24. Such a communication module 24 can be present at each wind power installation of the wind power installations 2. Said communication module can also be referred to as wind power installation interface.

[0085] It is proposed, then, that the control module 18, which can also be referred to as windfarm control module, obtains at least one form state from the wind power installations 2. This is depicted in FIG. 3 as form signal 26, using which at least one form state is passed back to the control module 18. Said form signal 26 with at least one form state is passed back here from the wind power installations 2, in particular from at least one communication module 24, to the output module 22 of the control module 18. In this respect, the output module 22 forms a state input of the control module 18. Consequently, the communication module 24 cannot only operate for the purpose of recording the manipulated variable 20, but also output data in the other direction. Likewise, the output module 22 not only outputs the manipulated variable or a plurality of manipulated variables 20, but can also receive and process further one or a plurality of form states.

[0086] The further processing of the at least one form state is then carried out such that at least one controller contained in the control module 18 is altered in terms of its parametrization and additionally or alternatively in terms of its structure. This alteration can be performed by the output module 22 or a different part of the control module 18.

[0087] The at least one form state that is passed back using the form signal 26 can firstly be a state of the wind power installations 2 which contain said communication module 24 in accordance with FIG. 3. However, consideration is also given to the wind power installations recording ambient conditions and transmitting them to the control module 18 via said form signal 26, or in some other way.

[0088] In this case, the transmission of the form signal 26 is also representative of the inputting of other variables that do not originate directly from the wind power installations 2. They may include, for example, whether and how many STATCOM installations are present in the windfarm. In this respect, said communication module 24 is also representative of many communication modules. In particular, each wind power installation 2 can have a dedicated communication module 24. In this sense other elements in the windfarm, such as the STATCOM installation mentioned or else a battery store, can also have such a communication module.

[0089] Moreover, the output module 22, which obtains said form signal or many form signals 26, can itself perform a first evaluation. By way of example, consideration is given to all elements in the form, that is to say in particular all wind power installations and also the other additional apparatuses such as STATCOM installation or battery stores, transmitting content-related information about the representatively illustrated form signal 26 to the control module 18. From the fact that these installations transmit such information, the output module 22 can also recognize how many and which elements, that is to say which apparatuses, transmit such data. Accordingly, the output module 22 can thereby also determine the number of relevant apparatuses, elements or installations in the form and correspondingly process further or pass on the latter within the control module 18.

[0090] In this respect, consideration is also given to the controlled system 4, which concerns in particular properties of the internal form network, likewise transferring information in the sense of the form signal 26 to the control module. To that end, provision can be made of measurement units in or at the internal form network, for example, which measurement units can have a communication module 24.

[0091] The controlled system 4 is subject in particular to voltage changes, changes in connected consumers and variations of the impedance Z thereof, in particular the imaginary portion X thereof and the real portion R thereof. Such information can be passed back to the control module 18 as form state via the form signal. The influence of these variables is identified as disturbance influence 28 as influence arrow into the controlled system 4.

[0092] Disturbance variables 30 that act on the wind power installations 2 are likewise identified by means of such an influence arrow. The proposed adaptation of the at least one controller in the control module 18 by means of the feedback of at least one form state via the form signal 26 thus also makes it possible to take account of such disturbance influences 30 affecting the wind power installations and also disturbance influences 28 affecting the controlled system. The disturbance variables 30 affecting the wind power installations are primarily the wind, in particular changes in wind speed, wind direction, or the varying occurrence of gusts.

[0093] Furthermore, the control structure in FIG. 3 has a setpoint value device 32. Said setpoint value device can predefine the reference variable 14. To that end, it can evaluate various predefinitions input externally, select therefrom and/or carry out a prioritization. To that end, external predefinitions 34 can be predefined in particular by an operator of the electrical supply network 8 and be correspondingly input into the setpoint value device 32. However, consideration is also given to an inputting, in particular by means of service personnel, via a SCADA system 36. Further possibilities of an external inputting are also conceivable, which are indicated here by the block 38.

[0094] Consequently, the control of the control module 18, in particular of the controllers contained therein, for the control of the active power P and the reactive power Q, can firstly be initialized or put into operation in a simple manner and thus also in a reliable manner. Only the signals that are input into the output module 22 as form signal 26 need be evaluated for this purpose. Furthermore, in this manner the control can also be adapted to changing conditions in the form.

[0095] FIG. 4 shows a diagram of a power characteristic curve P for further illustration of the invention. Here the power P and also a power coefficient C.sub.P are plotted against the wind speed V.sub.W. FIG. 4 can in particular clarify that a different amount of power can be generated depending on the prevailing wind speed V.sub.W. However, that also means that the relevant wind power installation can react to changes dynamically in varying ways.

[0096] Consequently, a further aspect of the underlying invention consists in improving an active power controller for a windfarm in as much as a static controller is replaced by an adaptive controller. Said adaptive controller recognizes different operating points of the windfarm or of other components in the windfarm and adapts to the circumstances. In this case, it can maintain its structure and adapt it by means of parameters, or the type of controller or the control structure is even altered depending on the operating point, for example from a PID controller to a PI controller. Consideration is also given to connecting in an additional filter for a controller deviation.

[0097] One consideration here is that a power output or the dynamic range of a power provision of the wind power installation is dependent on the wind. On the basis of the power curve P in FIG. 4 it can be discerned that the maximum power of the wind power installation is dependent on the wind speed.

[0098] From said curve it is possible to comprehend the exemplary consideration that for the case where the intention is to achieve an operating point at P=1200 kW, this can be carried out more rapidly if a wind speed of 15 m/s prevails than if only a wind speed of 9 m/s were available at the wind power installation. This is essentially a matter of accelerating the aerodynamic rotor to the required rotational speed as rapidly as possible. This occurs more rapidly if the wind speed at the installation is greater than necessary.

[0099] If the wind situation within the windfarm is sufficiently known, this information can concomitantly influence the controller and thus lead to a better control behavior. In the same way, other aspects such as gusty winds can also be recognized and the controller can concomitantly process this information. This is based on the insight that at such an operating point of operating the power control of the wind power installation itself causes relatively high power fluctuations, namely owing to the internal controllers, in particular rotational speed, power and pitch control. This would not occur, or would occur to a lesser extent, in the event of a comparatively constant wind prevailing, for example. In accordance with one proposal, for this purpose it is proposed to smooth the output variable of the windfarm controller in order that additional stimuli from the windfarm controller do not also affect the power control of the wind power installation. In this respect, it is thus possible to provide a realization by means of a filter as supplementary element. In this respect, such a filter can constitute a supplementation or alteration of the controller.

[0100] FIG. 5 shows a control structure in accordance with a further embodiment. In this control structure 50, firstly external predefinitions are predefined, in particular the setpoint values for active power P.sub.setpoint, reactive power Q.sub.setpoint, the voltage level U.sub.setpoint and the phase angle Phi.sub.setpoint (or .sub.setpoint). The last four variables, in particular, can be incorporated in a reactive power preliminary controller 54, which can comprise a Q controller, U controller, Phi controller (or controller), Q(dU) controller and a Q(P) controller.

[0101] The result of said reactive power preliminary controller 54 can then be input into a reactive power operating point controller 56. The active power setpoint value P.sub.setpoint can likewise directly influence a reactive power operating point controller 58 in a similar way. What is thus achieved is that the active power P.sub.setpoint provided and also the reactive power Q.sub.setpoint provided are not switched directly as setpoint value to the active power controller 68 and reactive power controller 66, respectively. In a manner similar to the reactive power operating point controller 56 and active power operating point controller 58, various other auxiliary controllers 60 are also provided, which concern various other variables. These include possible stopping of the windfarm (windfarm stop), taking into account a maximum active power (P.sub.max windfarm), a frequency-dependent power control (P(f) control), a control of the power change (dP/dt control) and an apparent power limitation (apparent power limitation P(S)). These auxiliary controllers 60 ultimately concern the active power control. They act on an active power block 61, which is part of a management block 64. Said active power block 61 then inputs an active power setpoint value into the actual active power controller 68. In this respect, said active power controller 68 is a controller which would be arranged in the control module 18 in accordance with the structure in FIG. 3. The active power controller 68 can thus be part of a windfarm control module 18. Said active power controller 68 then outputs an active power operating point P.sub.set to the wind power installations.

[0102] In a structurally similar manner, auxiliary controllers 62 are also provided for the reactive power predefinition, said auxiliary controllers concerning a reactive power change with respect to time (dQ/dt), also an apparent power limitation (apparent power limitation P(S)), and a limitation of a PQ curve at the form level (PQ curve (Q limit) at form level). These auxiliary controllers 62 together with the reactive power operating point controller 56 act on the reactive power block 63, which is likewise part of the management block 64. The reactive power block 63 then passes a setpoint value directly to the reactive power controller 66. The reactive power controller 66 outputs a reactive power operating point Q.sub.set to the wind power installations.

[0103] For the purpose of improvement it is then proposed to pass information back from the windfarm as form states 76 and 78 to the reactive power controller 66 and active power controller 68, respectively. Said form states 76 and 78 can also be identical. In any case it is then proposed here that the active power controller 68 is dependent on the form states 78 and can change in terms of its parametrization and/or structure in a manner dependent thereon. In the same way it is proposed that the reactive power controller 66 can change depending on the form states 76. For said reactive power controller, too, consideration is given to a change in terms of the parametrization and also the structure. As a result, it is possible to achieve a good adaptation of these two controllers to the situation in the form and in particular also to changes of situations in the form.

[0104] Furthermore, a parametrization module or stage 70 is proposed, which likewise obtains form states, this not being depicted here. On the basis of such form states, the parametrization module 70 can independently perform a parametrization, if appropriate also structuring or selection of options, for the reactive power preliminary controller and also for the reactive power operating point controller 56, active power operating point controller 58 and the auxiliary controllers 60 and 62. It is additionally possible to provide a parametrization, structure change or option selection for the management block 64. Consequently, what can be achieved here, too, is that the implementation of controller structures in particular upon the start-up of the form or of the form computer can be performed automatically or largely automatically by said parametrization module 70. That not only facilitates the start-up, but also avoids errors.

[0105] FIG. 6 illustrates a structure of a PI controller. Here a PI controller is shown basically in a known way, which PI controller can be described by a proportionality constant K.sub.P and an integration constant K.sub.I. Its input is generally formed by the error e and it outputs the manipulated variable u as output variable. Such parameters can be adapted for the purpose of parametrization. By way of example, which should be understood merely as an exemplary example, the integration constant K.sub.I can be calculated as a product of a nominal constant or basic constant K.sub.I0 and the quotient of available rated power of the windfarm P.sub.PA divided by the rated power of the windfarm P.sub.PN.

[0106] In this respect, FIG. 6 shows one example of a parameter alteration, and FIG. 7 shows one example of a structure alteration, namely how this can be implemented. This structure in FIG. 7 is also illustrated as a simplification for explanation purposes. FIG. 7 is also based on a controller which obtains a control error e as input and outputs a manipulated variable u. As the actual controller here three exemplary blocks are provided, namely a PI controller, which is designated as PI for simplification, a PT1 controller, which is designated as PT1 for simplification, and a PID controller, which is designated as PID for simplification.

[0107] Only one of these three controllers PI, PT1 and PID is active in each case. To that end, the switchover apparatus 80, which has two individual synchronized partial switching blocks, can carry out a switchover between these three exemplary controllers and further controllers. By way of example, these can be switched depending on the number of available wind power installations in the windfarm. For this purpose, by way of example, this value of the number of available wind power installations is identified by the variable i. This variable i can assume values from 1 to n, wherein n corresponds to the maximum number of wind power installations in the form. Theoretically, i could also assume a value 0, except in that case no wind power installation in the form would be active and any controller selection would then be pointless.

[0108] In any case it is assumed here that the number of available wind power installations i can range from 1 to n, and it is proposed here that the switchover apparatus 80 switches over between these controllers depending on this number of available wind power installations i. Such a switchover can also be carried out in a process computer, of course. Consequently, it is thus also possible to select or to alter different controller structures, depending on states of the windfarm, illustrated on the basis of the example of the number of available wind power installations in FIG. 7. The realization is effected in such a way that such different controllers are stored for selection.