Field of the invention

The invention relates to a method of controlling wind turbines in a wind farm and to a wind farm controlled by such method.

Background of the invention

Communication between a wind turbine manager such as an owner of a wind turbines and the wind turbine is performed via different data communication systems. In case the wind turbine manager needs to communicate with wind turbine of different types the wind turbine manager may face a problem.

This problem is handled by US patent application US20090254224 which describes a wind turbine having at least two so called protocol handlers enabling the wind turbine to communicate with two different data communication systems at the same time.

In another US patent application US2009281675 is described a system enabling monitoring and control of at least two wind farms. This is done by defining a so called namespace for the individual wind farms. In relation to figure 6 of US2009281675 the namespace is described torn make it possible to determine which elements of a wind farm it should be possible to monitor and control.

Brief description of the invention

The present invention discloses a data communication system for managing data communication in a renewable energy generating system, the renewable energy generating system comprising: a plurality of wind turbines, and a first level control system for at least partly controlling at least part of the plurality of wind turbines, the first level control system comprising first and second data mapping means and a data storage, wherein the first data mapping means is configured for normalising data elements from said at least part of the plurality of wind turbines according to a set of normalised data elements, and storing the normalised data elements in the data storage, wherein the second data mapping means is configured for mapping the normalised data elements according to a least one data protocol, wherein the normalised data elements provides a common communication interface between the first level control system and said at least part of the plurality of different wind turbines, and wherein said at least one data protocol provides a

communication interface between at least one second level control system and the normalised data elements of the first level control system.

Management of the data object models including data elements and different communication protocols is often done manually by configuration. Changes such as names, threshold values, etc. in data elements and / or change of the used data protocol are isolated and can be dealt with by updating a configuration in a central place.

The present invention is advantageous in that it eases wind farm data management as the present invention separates the complexity of communicate data from a wind turbine in a wind part to a second level control system. This is done by breaking down the task in different blocks by means of the the first and second data mapping means. Furthermore the present invention gathers the complexity of the data communication in one place such as in a first level controller thereby facilitaing an easy accessible overview of wind turbines of a wind park e.g. from a second level controller. Hence the present invention enables a lower risk of making failures, the creation of a data communication path between first and second level controllers will be faster, updating data object models such as data elemetns in the wind farm network is increased, etc.

The first level control system may be dedicated to normalising and mapping of data from the wind turbines and second level contol systems. Alternatively the first level control system may be part of a wind farm controller i.e. a central part of a control system for park power management as will be well known by the skilled person. No matter which, the first level control system is configured for bidirectional communication both between the wind turines and the second level control system.

The normalisation may also be referred to as representation mapping facilitating an easy access to the wind turbines in order to update the control system of the wind turbines with additions and/or changes to the dataset in the wind turbines control system as well as maintaining a uniform overview. The invention is advantageous if one first level control system are to communicate with more than one second level control systems using different data protocols. This is because of the flexibility provided, e.g. when data elements from wind turbines are normalised the invention facilities easy change and/or addition of new data protocol for communication with second level control systems

It should be mentioned that the data elements received by the first control system from the wind turbines are typically communicated according to a data protocol. Each type of wind turbine may communicate along different data protocols.

It should be mentioned that data storage may be RAM memory block, hard disk, etc.

It should be noted that in most cases the set of normalised data is predefined. This is advantageous in that preparation such as allocation of storage in the database and reference hereto could be made more user-friendly. Furthermore by having a set of predefined data which is used to normalise data elements from a wind turbine increase the amount of preparation of the data communication system which can be made before the wind turbines are erected and commissioned. A set of normalised data could comprise wind speed, active power, generator speed, rotor speed, temperatures, pressures, etc.

According to an embodiment of the invention the renewable energy generating system further comprising a second level control system configured for bidirectional

communication with the first level control system.

According to an embodiment of the invention the second level control system may be an end or top level ( second level) user managed by e.g. the owner or operator of the renewable energy generating system, operator of the utility grid to which the renewable energy generating system is connected to, etc.

Furthermore it should be noted that the second level control system may communicate with data systems managed by owners or operators. In this situation these owners or operators may be defined as end users. As mentioned in this case the end user may be a data system handling data from the first level control system automatically e.g. by using an automatic recipient of data from the first level control system such as an automatic dispatcher.

Alternatively the second level control system could be the end user.

According to an embodiment of the invention the first and/or the second control system further facilitate monitoring and/or control of the least a part of the renewable energy generating system.

According to an embodiment of the invention said first and/or second level control system are a SCADA system. The first and/or second control systems may be part of the control of the wind turbines. This may be en form of monitoring and or control of the wind turbines i.e. part of the wind farm power management. Often such park power management systems are implemented as SCADA (SCADA: Supervisory Control And Data Acquisition) systems. This is advantages in that SCADA systems are well tested and facilitates making friendly user-interfaces.

According to an embodiment of the invention the second level control system

communicates with a plurality of different first level control systems.

For an operator having to control more than one wind farms (comprising different types of wind turbines communicating according to different types of data protocols) it is advantageous to be able to communicate with these wind farms according to a predetermined data protocol and/or based on the normalised data elements. This is because the operator only needs to use one data protocol to communicate with all first level control systems of the more than one wind farms and via this data protocol the operator is even allowed to obtain data elements from the individual wind turbines of these wind parks It should be noted that a first level control system may also control renewable energy generating systems such as solar systems

According to an embodiment of the invention said predetermined data protocol is selected from one of the list comprising: OPC, Modbus, DNP3, MMS.

It should be mentioned that of course other protocols than mentioned above may also be used. This includes proprietary protocols and protocols following specific standards such as IEC61400-25, IEC60870-5-104, etc.

According to an embodiment of the invention the data elements from a wind turbine are normalised according to a data protocol.

According to an embodiment of the invention the plurality of different wind turbines communicates with the first level controller according to a wind turbine data protocol and wherein the first level controller communicates with the second level controller according to at least one predetermined data protocol.

A wind farm may include wind turbines of different types each type communicating via different wind turbine data protocols also simply referred to as data protocol with first level control system.

Depending on request from the operator of the second level controller the type of the at least one predetermined data protocol is decided. It should be noted that the wind turbine data protocol and the predetermined data protocol could be the same protocol.

According to an embodiment of the invention the normalising of data elements is a N:l mapping. As mentioned wind turbines of a wind farm may communicate with a first level control system according to a plurality of different data protocols. To ease communication to a second level control system the first level control system normalises data from a plurality of data protocols (referred to as N) to a single understanding of data (referred to as 1) such as one data protocol.

According to an embodiment of the invention the first data mapping means and/or the second data mapping means is configurable run-time.

Being able to configure the data mapping means while the wind turbine is in operation (run-time configurable) is very advantageous especial in the prototype phase of the wind turbine development where a lot of changes to the control system e.g. software, variables, values etc. are expected.

More over the invention relates to a wind farm having a data communication system according to any of the claims 1-10. Figures

A few exemplary embodiments of the invention will be described in more detail in the following with reference to the figures, of which: figure 1 illustrates a wind turbine according to an embodiment of the invention, figure 2 illustrates a renewable energy generating system according to an embodiment of the invention, and figure 3 illustrates an embodiment of the communication between wind turbines and first and second level controllers,

Detailed description of the invention

Figure 1 illustrates a wind turbine 3 according to an embodiment of the invention. The wind turbine 3 comprises a tower 11, a nacelle 12, a hub 13 and two or more blades 14. The blades 14 of the wind turbine 3 are rotatably mounted on the hub 13, together with which they are referred to as the rotor. The rotation of a blade 14 along its longitudinal axial is referred to as pitch. The wind turbine 3 is controlled by a control system comprising a wind turbine controller 15, sub controllers / sensors / actuators 16 for controlling different parts of the wind turbine 3 and communication lines 10. The wind turbine 3 further comprises a generator and a power converter. The generator transforms rotational energy from the rotor into electrical energy and the power converter "shapes" the electrical energy from the generator into a form, which complies with utility grid demands. The electrical energy is transported from the generator to the converter and further to the utility grid via high voltage cables.

Figure 2 illustrates a renewable energy generating system 1 according to an embodiment of the invention. The illustrated renewable energy system 1 comprises wind farms 2a, 2b, .., 2n each comprising a plurality of wind turbines 3. The wind turbines 3 may be of different types and therefore communication to a from the wind turbines 3 may be performed according to different data protocols 4a, 4b, 4n.

One type of wind turbines 3 could be a Vestas wind turbine, another type could be a Gamesa wind turbine, yet another type could be a Mitsubishi wind turbine, etc. The different types could also be variants within the portfolio of the different wind turbine manufactures.

One type of data protocol 4 could be OPC (the abbreviation origins from OLE (Object Linking and Embedding) for Process Control), Modbus, DNP3, (DNP: Distributed Network Protocol), MMS (MMS: Microsoft Media Server), IEC standards such as 61400-25 and 60870-5-104, etc.

The wind farms 2 may be controlled by means of wind farm controllers also referred to as first level controllers 5 communicating with the individual wind turbine controllers 15. The first level controllers 5 may comprise first data mapping means 6, a data base 7 for storing normalised data and second data mapping means 8. Furthermore the first level controllers 5 may comprise not illustrated other means for executing, reading, writing, storing, etc. data related to the wind farm 2 or the individual wind turbines 3. It should be noted that the mapping functionality according to the present invention is not bound to be part of the wind farm controller, but that it would be preferred at least to have the mapping functionality closed to in that the data communication network is established from the wind farm controller 5 to the individual wind turbines 3 of the wind farm 2.

The data communication may comprise wind turbine control system, communication to first level control system 5 / wind farm controller and communication to second level control system 9.

As illustrated, one or more wind farms 2 may be operated (e.g. controlled, monitored, etc.) by a wind farm manager via a second level controller 9. The second level controller 9 may communicate with the wind farms 2 by means of data protocols 4 as described above in relation to communication between wind turbines and 3 and first level controllers 5.

It should be noted that data protocols 4 used for data communication by wind turbines 3 or second control system 9 may be known when implementing the first level control system 5 in a wind farm 2. Alternatively none of the data protocols 4 are known and relevant information of a plurality of relevant data protocols 4 may be stored e.g. in the data storage 7. In both cases the data storage 7 may be consulted by the data processor (not illustrated) processing data of the first level control system 5 to get information primarily of variable names but also relating to control commands, configurations parameters, etc.

Figure 3 illustrates the renewable energy generation system 1 of figure 2 in more details. A first wind farm 2a is illustrated comprising a plurality of wind turbines 3a of the same type. The individual wind turbines 3a are communicating with a wind farm controller i.e. a first level controller 5a by means of the same data protocol 4a which could be a proprietary data protocol. At the first level controller 5a the first data mapping means 6 are normalising data elements from the wind turbines 3a. Preferably these data elements are stored in a data storage 7. This normalising of data elements may also sometimes be referred to as a mapping many to one (N:l).

When normalising data the data may be converted into a predetermined data protocol 4 i.e. e.g. variable names used in the wind turbine is converted into variable names used in the predetermined data protocol 4. Alternatively the data elements are translated into customer defined variable names. No matter which a second mapping may be necessary to convert the variable names to variables names complying with data protocols 4 used by second level control system(s) 9.

From the data storage 7 the second data mapping means 8 are mapping the normalised data elements to fit the data protocol 4d which could be the Modbus data protocol used for data communication by the second level controller 9. Data elements may refer to any kind of data exchanged between the second level controller 9 and the wind turbines 3a as described by the following non-limiting example of normalising of data elements.

The measured wind speed is an example of a data element which may be obtained by the wind turbines 3a and send to the first or second level controller 5a, 9. In the same way the first or second level controller 5a, 9 could send forecasts of wind speed to the wind turbines 3a. Another example could be output of the individual wind turbines for obtaining a common output from the wind farm 2a. The wind turbines could communicate data defining actual power output to the first and second level controller 5a, 9 and the other way the second level controller 9 could send power demand to the first level controller 5a or directly to the individual wind turbines 3a. Typical communication from the second level controller is control signals for starting, stopping, output, reset, etc.

Other data elements are not relevant for bidirectional communication between first and second level controller 5a, 9 and wind turbines 3a. Using the amount of produced power as example the proprietary data protocol 4a used by the wind turbines 3a provides data to the first level controller 5a in a variable named VA_OUTPUT. As mentioned in this embodiment, the second level controller 9

communicating with the first level controller 5a via the Modbus data protocol 4d. In the Modbus data protocol 4d the variable used for communicating the amount of output from the wind turbine may be FA M1_WT1_0UTPUT. Beside the different names the data format may also divert. Hence the proprietary data protocol 4a may use a Binary representation of data whereas the Modbus data protocol 4d may use a Hexadecimal representation or the like.

To enable communication between the wind turbines 3a and the second level controller 9 despite the different data protocols 4a, 4d the first level controller comprises first data mapping means 6. The first data mapping means 6 are normalising the data e.g. by mapping (translating, copying or the like) the data of the variable VA_OUTPUT into a location in the data storage 7 which may be referred to as WTl_OUTPUT. This normalising may include identification of which of the wind turbines 3a the data is communicated from.

As mentioned the first level controller 5a also comprises second data mapping means 8. The second data mapping means 8 are mapping (translating, copying or the like) the data of the variable VTl_OUTPUT from its location the data storage 7 to the variable

FARMl_WTl_OUTPUT. Thereby enabling bidirectional communication between the second level controller 9 and the individual wind turbines 3a.

The normalisation and mapping of data performed by the first level controller 5 is especially advantageous when looking at the wind farm 2b of figure 3. Here the wind farm 2b comprises three different types of wind turbines 3a, 3b and 3c each communication with different data protocols 4a, 4b and 4c such as e.g. OPC, proprietary and one of the data protocols defined by the IEC (IEC: International Electro-technical Commission) standard. One or more first mapping means 6 are normalising data elements from the wind turbines as described above. This many to one mapping of data enables easy access to the data by the second level controller 9. Either directly if the data elements are normalised or mapped according to the data protocol 4d used by the second level controller 9 or via second data mapping means 8 of the first level controller 5b.

The reference to first and second data mapping means is only for ease understanding of the invention and it should be stressed that the first and second data mapping means could be the same physical element such as a data processor communicating with the data storage 7 and other relevant and necessary elements to perform the normalisation and/or mapping of data elements. It should be mentioned that more than one second level controllers 9 could be connected the one first level controller as indicated by dashed lines on figure 3.

Returning to the normalization or mapping function this may comprise multiple layers with each an area of responsibility and an interface to allow for dynamic changes of the normalized data elements. These areas could be responsible for proper units handling (i.e. meters or millimeters, F or C, etc.), scaling, converting of data, etc.

It is not unusual that a wind turbine comprises more than 3.500 different data elements including different representation of one value. As an example could be mentioned that the wind turbine facilitates several representations of measured wind speed such as raw measurement from the anemometer, IS average and 10S average.

Especially during optimizing of prototypes of wind turbines and during commissioning there is a need for changing or updating data elements at the wind turbine 3. The present invention facilitates this without the second level controller being aware and due to the normalizing functionality and mapping according to the data protocol 4 used by the second level controller 9 the second level controller 9 is always able to provide an updated and uniform presentation of the wind turbines 3

It should be noted that if no mapping rules are determined the first mapping controller 6 may map data elements from the wind turbines 3 according to default rules i.e. into default variable names etc. In the same way relating to the different data elements if not variables are chosen default data elements are chosen such as 1 second average of measured wind speed etc. Typically the default data set would comprise a set of data comprising about 200 different data elements. Of course this default set of data elements can be customized by a user. It should be noted that it is possible to perform multiple layers of mapping hence it is possible to create a variable name which refers back to data elements of the default set. This could be relevant in the case where a variable name has to be changed and the old name has to be kept. Then the new and old name would refer to the same value. It should be noted that the normalisation could also be used in park power management.

It should be noted that the above described figures are illustrating different embodiments of the invention and that all described features may apply to all figures even not illustrated. Further when referring to e.g. a subgroup of wind turbine such as type 3a, the description and function of this subgroup may apply to all other types of wind turbines 3. In the same way does other specific disclosure of features or elements of subgroups also apply to genuine of features or elements.

List of reference numbers

1. Renewable energy generating system

2. Wind farm

3. Wind turbine

4. Data protocol

5. First level control system

6. First data mapping means

7. Data storage

8. Second data mapping means

9. Second level control system

10. Communication lines

11. Tower

12. Nacelle

13. Hub

14. Blade

15. Wind turbine controller

16. Sub-controller / sensor / actuator