WO2011150929A1

WO2011150929A1 - A computer system and method for controlling and/or monitoring a wind power plant

Info

Publication number: WO2011150929A1
Application number: PCT/DK2011/050181
Authority: WO
Inventors: Tage Kristensen; Siew Hoon Lim
Original assignee: Vestas Wind Systems A/S
Priority date: 2010-05-31
Filing date: 2011-05-27
Publication date: 2011-12-08

Abstract

The invention relates to a wind power computer system (50) comprising a first computer system (10) with a first software system (OS1) and a second computer system (20) with a second software system (OS2) using virtualization technology. The first computer system (10) and the second computer system (20) are managed by a single computer hardware platform (30). The wind power computer system (50) further comprises a hypervisor (40) arranged for allowing the first and the second software systems (OS1, OS2) to share the computer hardware platform (30) as virtually separate computer systems.

Description

A COMPUTER SYSTEM AND METHOD FOR CONTROLLING AND/OR MONITORING A WIND POWER PLANT

FIELD OF THE INVENTION

5 The present invention relates to a wind power computer system

comprising a first computer system with a first software system and a second computer system with a second software system.

BACKGROUND OF THE INVENTION

0

A wind turbine generator comprises a rotor connected to a generator for converting mechanical energy in the turbine to electrical energy. A wind turbine generator is usually controlled by an on-board wind turbine control system comprising software and hardware components. Typically, a wind 5 turbine generator is composed of several subunits, and the wind turbine control system may be distributed to controllers at different subunits, e.g., in the nacelle and tower. The wind turbine control system may be connected to an external control and/or monitoring system from which it receives control commands and to which it sends data regarding the operation of the wind0 turbine. Such an external control and/or monitoring system may be a SCADA (supervisory control and data acquisition) system arranged for monitoring and controlling the operation of the wind turbine. Typically, the external control and/or monitoring system is located remotely from the wind turbine generator so as to facilitate control and/or monitoring of the operation of the wind turbine5 generator from a remote location.

Wind turbine generators may be grouped into a wind power plant or wind park. Such a wind power plant is a group of wind turbines in the same location used for production of electric power. Individual turbines are typically0 interconnected with a power collection system and communications network. The wind power plant is further connected to an electrical power network for providing the electrical energy generated by the wind turbine generators to the power network. The wind power plant typically comprises a substation with components for transforming the electrical energy and/or a wind power plant computer system for performing control of the wind turbine generators of the wind power plant. The wind power plant may comprise power plant controller with wind power plant computer systems arranged for communication with the wind turbine control systems of the individual wind turbine generators of the wind power plant as well as with the external control and/or monitoring system.

Various categories of computer systems are used in wind power plants and in wind turbine generators, e.g., non-real time, real-time and safety-critical computer systems. Hence, it would be advantageous to provide a simplified computer system for wind turbine generators and/or wind power plants.

SUMMARY OF THE INVENTION

Accordingly, it may be seen as an object of the present invention to provide a simplified wind power computer system. The invention is particularly, but not exclusively, advantageous for providing flexibility, footprint, and cost reduction without impairing the reliability of the wind power computing system.

The wind power computer system of the invention comprises a first computer system with a first software system and a second computer system with a second software system. In one embodiment of the invention, the first computer system and the second computer system are managed on a single computer hardware platform using virtualization technology. To this end, the wind power computer system further comprises a hypervisor configured to provide virtual computer systems that allow the first and the second software systems to share the underlying physical computer hardware platform while operating as virtually separate computer systems. The term "software system" as used herein is meant to cover both a standalone application and/or a system consisting of operating system and application programs.

Virtualization is the creation of a virtual (rather than a physical) version of a computing hardware platform. Virtualization allows a single physical computer hardware resource, such as a server, to provide computer resources that support or host multiple guest operating systems and/or guest

applications. Examples of computer resources that may be virtualized include operating systems, servers, storage devices, and network resources.

Virtualization may be performed by a software program known as a virtual machine monitor (VMM) or hypervisor. A hypervisor comprises computer software and/or hardware that allows multiple software systems, such as operating systems, to share a single hardware host or platform. Each software system, e.g., operating system, appears to have exclusive use of the host's processor, memory, and other resources. However, the hypervisor actually controls the host processor and resources, allocating what resources are needed to each software system in turn and making sure that the guest operating systems (called virtual machines) cannot disrupt each other. Embodiments of the invention thus propose to use virtualization techniques, such as a hypervisor running on a single hardware platform, to provide two or more virtual computer systems instead of using multiple physical hardware platforms. Thus, the same hardware platform is used to host different applications which have hitherto been placed on separate hardware platforms. This reduces costs, power consumption as well as size and weight of the wind power computer system, and it simplifies installation and

configuration of the wind power computer system.

The first virtual computer system may be arranged for controlling the wind power system and the second virtual computer system may be arranged for monitoring the wind power system. In conventional wind power systems, the monitoring and the control of the wind power system, i.e., a wind turbine generator or a wind power plant, are carried out at individual computer hardware platforms. The invention thus proposes to carry out control and monitoring at the same computer hardware platform using the hypervisor to separate these functionalities.

The first and second virtual computer systems may each be of one of the following categories: real-time, non-real-time and safety-critical. Thus, no matter which kind of category of computer systems, the first and second virtual computer systems may be managed or executed on a single hardware platform by the hypervisor.

Moreover, the first and second virtual computer systems may be of different ones of the following categories: real-time, non-real-time and safety- critical. Typically, these categories of computer systems have been carried out at individual computer hardware platforms. The invention proposes to provide these categories of computer systems on the same computer hardware platform using the hypervisor to separate the categories of computer systems. Instead of using separate physical computers or hardware platforms for the various categories of computer systems, non-real time, real-time and safety- critical computer systems, within each wind turbine sub-unit and power plant controller, only one hardware platform may be necessary at each subunit of a wind turbine and only one hardware platform may suffice for the power plant controller.

In one embodiment, the wind power computer system is a computer system within a wind turbine generator. Additionally or alternatively, the wind power computer system is a computer system within a wind power plant control system and is arranged to control and/or monitor the operation of a plurality of wind turbine generators in a wind power plant. The computer systems in wind turbine generator(s) and/or in a wind power plant controller are typically not heavily loaded and, thus, will typically have enough unused capacity to be capable of supporting two or more applications. In one embodiment, a method is provided for operating a wind power computer system. The method includes creating a first and second virtual computer systems hosted on a computer hardware platform of the wind power computer system using the hypervisor. The method further includes hosting a first operating system on the first virtual computer system and hosting a second operating system on the second virtual computer system. The hypervisor is configured to allow the first and second operating systems to share the computer hardware platform as virtually separate computer systems.

It should be understood that the assembling of more than one wind power computer system into one hardware platform may be carried out in any subunit control system of the wind turbine generator as well as in the power plant controller.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will now be explained, by way of example only, with reference to the accompanying Figures, where Figure 1 is a schematic drawing of a wind turbine;

Figure 2 is a schematic drawing of wind power computer system according to the invention; Figure 3 is a schematic drawing of a wind power computer system according to another embodiement of the invention; Figure 4 is a schematic drawing of a wind power computer system according to yet another embodiment of the invention; and Figure 5 is a schematic drawing of a virtual computer system according to an aspect of embodiments of the invention.

Similar reference numbers are meant to denote similar elements throughout the figures.

DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 shows a wind turbine generator 100. The wind turbine generator 100 includes a tower 1 having a number of tower sections (not shown in figure 1 ), a nacelle 2 positioned on top of the tower 1 , and a rotor extending from the nacelle 2. The tower 1 is erected on a foundation 5 built in the ground. Alternatively, the foundation 5 might be built on the sea floor in the case where the wind turbine is an offshore wind turbine. The rotor is rotatable with respect to the nacelle 2, and includes a hub 3 and one or more blades 4. The rotor is arranged to be brought into rotation in respect to the nacelle 2 by wind incident on the blades 4. The mechanical energy from the rotation of the rotor is converted into electrical energy by a generator in the nacelle 2. The electrical energy is subsequently converted to a fixed frequency electrical power to be supplied to a power grid. The wind turbine generator 100 may also form part of a wind power plant comprising a plurality of wind turbine generators 100. Although the wind turbine generator 100 shown in Figure 1 is shown as having two blades 4, it should be noted that a wind turbine generator may have different number of blades; a typical number of blades is three, but it is common to find wind turbines having one to four blades. The wind turbine generator 100 shown in Figure 1 is a Horizontal Axis Wind turbine (HAWT) as the rotor rotates about a substantially horizontal axis. It should be noted that the rotor may rotate about a vertical axis. Such a wind turbine generator having its rotor rotates about the vertical axis is known as a Vertical Axis Wind Turbine (VAWT). The embodiments described henceforth are not limited to HAWT having two blades. They may be implemented in both HAWT and VAWT, and in wind turbine generators having any appropriate number of blades 4 in the rotor.

Figure 2 is a schematic drawing of wind power computer system 50 according to the invention. The wind power computer system 50 may be a computer system in a wind turbine generator or in a wind power plant controller.

When in a wind turbine generator, the wind power computer system 50 may be a computer system arranged for controlling and/or monitoring the operation of the wind turbine generator. When in a wind power plant controller, the wind power computer system 50 may be arranged for controlling and/or monitoring a plurality of wind turbine generators within the wind power plant.

The wind power computer system 50 comprises the hypervisor 40 as well as the hardware platform 30, e.g., a multicore processor platform, arranged for executing more than one software system independently on a single platform as illustrated by the arrows between the hypervisor 40 and the first and second software system OS1 , OS2. The hypervisor 40 may also be arranged to assign individual hardware devices to each software system as illustrated by the arrows between the hypervisor 40 and the first and second set HW1 , HW2 of hardware devices. The software systems OS1 , OS2 may be operating systems, standalone applications, or systems each consisting of operating system and application programs. Advantageously, the operating systems, if present, may each be rebooted independently of the other. The wind power computer system 50 comprises a first computer system 10 having a first software system OS1 and a first set HW1 of hardware devices, such as a central processing unit (CPU), i.e., a processor or a microprocessor, a memory, input/output devices. The first set HW1 of hardware devices are arranged to be managed by the first software system OS1 as illustrated by the arrows in figure 2 between the first software system OS1 and the first set HW1 of hardware devices.

The wind power computer system 50 moreover comprises a second computer system 20 having a second software system OS2 and a second set HW2 of hardware devices, such as a central processing unit (CPU), i.e., a processor or a microprocessor, a memory, input/output devices. The second set HW2 of hardware devices are arranged to be managed by the second software system OS2 as illustrated by the arrows in figure 2 between the first software system OS1 and the first set HW1 of hardware devices.

The first and second computer systems 10, 20 are managed by the computer hardware platform 30 in the sense that the hardware platform 30 is arranged for executing the two software systems OS1 , OS2 as well as assigning the first set HW1 and the second set HW2, respectively, of hardware devices to the first software system OS1 and the second software system OS2, respectively. That is, the first and second computer systems 10, 20 may be embedded within the hardware platform 30. Thus, the hypervisor 40 provides virtualization of the physical resources of the computer hardware platform 30, which allows the first and the second software systems OS1 , OS2 to share the computer hardware platform 30 as virtually separate computer systems. The hypervisor 40 may provide the virtually separate computer systems 10, 20 through the use of virtualization techniques including, but not limited to, binary translation, hardware assisted virtualization, and/or paravirtualization. Binary translation is the emulation of one instruction set by another through translation of computer code. By way of example, binary translation may be used to translate code used by the software system OS1 hosted on the first computer system into code that is executable by the physical processors of the computer hardware platform 30. The software system OS1 may thereby be hosted by the hardware platform 30 using processors having incompatible code requirements. The hardware platform 30 may also be configured to facilitate virtualization by including processors and other hardware that supports virtualization. For example, processors including hardware assisted virtualization features are known to those having skill in the art and include x86 processors supporting VT-x technology, which are available from the Intel® Corporation of Santa Clara, California. The hypervisor 40 may also employ paravirtualization to allow the guest software systems OS1 , OS2 to run certain tasks outside of the virtual computer environment. Paravirtualization involves modifying the operating system so that the operating system takes into account that the operating system is running in a virtualized environment. This type of modification may allow the guest software systems OS1 , OS2 to relocate the execution of certain tasks to the non-virtual ized environment (i.e., directly to the computer resources of the underlying hardware platform 30). Paravirtualization may thereby allow increased performance of the overlying computer systems 10, 20 by avoiding inefficient virtual execution of code that would be more efficiently executed outside the virtual domain.

It should be noted that the hypervisor shown in figure 2 is of the kind where no host operation system is used. However, a hypervisor with a host operating system may also be conceivable as will be discussed below. Referring now to FIGS. 3-5 in which like numerals refer to like features in FIG. 2 and in accordance with an embodiment of the invention, a wind power computer system 50 includes the shared hardware platform 30 that serves as a host server, the hypervisor 40, and a plurality of virtual computer systems 64a- 64n. The shared hardware platform 30 provides the underlying physical computer hardware resources that the hypervisor 40 utilizes to provide virtual computing resources to the virtual computer systems 64a-64n. The

configuration of the wind power computer system 50 illustrated in FIG. 3 shows the hypervisor 40 managing the physical resources of the shared hardware platform 30 directly in what is commonly referred to as a "bare-metal" configuration. The wind power computer system 50 as illustrated in FIG. 4 further includes a host operating system 82, which may run on and manage the physical resources of the hardware platform 30. The configuration of the wind power computer system 50 as illustrated in FIG. 4 is commonly referred to as a "hosted virtualization" configuration. In a hosted virtualization system, the hypervisor 40 manages the allocation of system resources between the virtual computer systems 64a-64n and the host operating system 82, which manages the physical resources of the shared hardware platform 30. References to virtual computer systems 64a-64n in this application are understood to encompass both bare-metal and hosted virtualization configurations.

A guest operating system (OS) 70a-70n resides on each of the virtual computer systems 64a-64n provided by the hypervisor 40. The hypervisor 40 provides a virtual computing environment that allows one of the operating systems (OS's) 70a-70n to function within a respective one of the virtual computer systems 64a-64n as if each OS 70a-70n were loaded onto a compatible physical machine or hardware platform. The hypervisor 40 thus isolates each OS 70a-70n from the other OS's 70a-70n so that each OS 70a- 70n may reside and operate on the shared hardware platform 30

simultaneously. To this end and as best illustrated in Figure 5 for virtual computer system 64a, each of the virtual computer systems 64a-64n may include a virtual memory 65, a virtual processor 66, a virtual mass storage device 67, and a virtual I/O interface 68. These virtual resources 65-68 may be abstractions of actual computer resources created and mapped by the hypervisor 40 to an associated physical resource in the hardware platform 30.

Because the computer resources provided by the hypervisor 40 are abstractions of the physical resources of the hardware platform 30, the hypervisor 40 may provide a virtual computing environment that has no direct relationship to the underlying hardware platform 30. Each of the virtual computer systems 64a-64n may thereby provide a separate virtual system platform which supports the execution of the particular one of the OSs 70a-70n independently of the other virtual computer systems 64a-64n. That is, the OSs 70a-70n may be different operating systems with different hardware

requirements. Alternatively, two or more of the OSs 70a-70n may be instances of the same operating system. To isolate the particular one of the OSs 70a- 70n running inside each of the virtual computer systems 64a-64n, the OS 70a- 70n may be limited by the hypervisor 40 to the virtual resources associated with the virtual computer system 64a-64n on which the OS 70a-70n is loaded. Thus, in some embodiments the OSs 70a-70n may not directly access resources outside of the virtual resources 65-68 provided by the hypervisor 40. However, as discussed above, in systems using paravirtualization, the OSs 70a-70n may have limited access to computer system resources outside of the virtual environment. Each of the OSs 70a-70n may be a computer program that manages the virtual computer hardware resources provided by the hypervisor 40, which thereby provides a common platform on which a guest application 76a-76n may run. Each of the OSs 70a-70n may thereby operate as an intermediary between the particular one of the applications 76a-76n and the virtual computer system 64a-64n provided by the hypervisor 40 on which the OS 70a- 70n and application 76a-76n are running. Each application 76a-76n may thereby request that the associated OS 70a-70n perform tasks, such as store data to virtual memory 65, as the application 76a-76n executes its instructions.

A general purpose OS will typically attempt to share resources between various applications running on the OS in a manner that optimizes the overall performance of the underlying hardware platform. As a result of this resource sharing, the amount of time a general purpose OS takes to execute a particular task for a particular application may vary depending on the operating

conditions of the hardware platform. In contrast, a real-time operating system (RTOS) is an operating system designed to provide consistent task completion times to an application. The overall performance and resource utilization efficiency of an RTOS with respect to a particular application may be lower than a general purpose OS due to this requirement for consistency. However, the timing consistency provided by the RTOS makes the RTOS useful for running applications that must respond in a predictable manner to real time events, such as is commonly encountered in real-time or safety-critical applications.

An RTOS, such as the VxWorks® RTOS commercially available from Wind River Systems of Alameda, California, may be used in safety-critical or real-time wind power computer system applications, such as wind turbine controllers, so that control loops and control algorithms may be run in a deterministic and highly reliable fashion. A general-purpose OS, such as the Windows® OS commercially available from Microsoft Corp. of Redmond Washington may, for example, be used to provide a graphical user interface and to support applications that display and log the wind turbine controller I/O data and status, control loop output, and process trends. By providing virtual computer systems 64a-64n running separate OS's 70a-70n, the hypervisor 40 may allow applications 76a-76n requiring an RTOS to run on the same hardware platform 30 as applications 76a-76n running on a general purpose OS. Safety-critical or real-time applications, such as applications that provide control loop and control algorithms to the wind turbine systems, may thereby be run on an RTOS sharing the single hardware platform 30 with a general purpose OS running non-real time applications such as Human Machine Interface (HMI) software, wind turbine controller diagnostic software, or a graphical user interface for a supervisory control and data acquisition (SCADA) application. The hypervisor 40 may thereby allow the capabilities offered by different operating systems to be provided on a single shared hardware platform 30. By way of example, a user of the wind power computer system 50 might use graphics services provided by a general purpose OS, such as the Windows® OS, in conjunction with an application providing deterministic processing running in an RTOS environment, such as the LabVIEW® RTOS commercially available from the National Instruments Corporation of Austin, Texas. By providing the ability to use different types of operating systems (e.g., a general purpose OS with an RTOS) on a single shared hardware platform serving as a wind turbine or wind power plant controller, hardware costs may be reduced by avoiding the need for a separate hardware platform for each OS.

By way of example, the applications 76a-76n may be applications used to perform wind turbine diagnostics during servicing and to monitor the status and trends of wind turbine performance for display on a graphical user interface and may be run on the single shared hardware platform 30. The hypervisor 40 may thereby allow computer system users to employ the latest state-of-art graphics technology available in general purpose operating systems, like the Windows® OS, on the same shared hardware platform 30 used to support wind turbine controller applications 76a-76n running on an RTOS. Diagnostics software and graphical displays running on the single shared hardware platform 30 may allow service engineers to more easily view live or historical trends without the need to have physically separate hardware platforms 30. The hypervisor 40 might thereby reduce the overall computer system footprint as compared to computer systems employing multiple hardware platforms 30 to support each of the required OS's 70a-70n.

Similarly, an application providing a HMI may installed in one or more of the virtual computer systems 64a-64n running a general purpose OS like Windows® OS to provide live and/or historical wind turbine information, which may be monitored and displayed continuously in a virtualized wind turbine controller. The information provided by these improved HMI applications may allow system operators to identify problems early so that the quality or life time of the wind turbine generator 100 may be extended as compared to a wind turbine generator lacking this type of monitoring capability. Because the virtual resources provided by the hypervisor 40 rely on the limited physical computing resources provided by the hardware platform 30, the guest OS's 70a-70n and guest applications 76a-76n running on the virtual computer system 64a-64n may compete for hardware platform 30 resources. To allow certain virtual computer systems 64a-64n to have guaranteed access to certain levels of computer resources, the hypervisor 40 may provide a mechanism by which system users may directly assign hardware platform resources, such as groups of processor cores, to an individual one of the OSs 70a-70n. For example, if a system user wishes to use a general purpose OS, such as Linux, in conjunction with an RTOS, the hypervisor 40 may allow dedicated or prioritized physical CPU and memory resources to be allocated to the virtual computer system 64a-64n hosting the RTOS to optimize overall system performance. The hypervisor 40 may thereby allow system designers to optimized available hardware platform resources by keeping processor cores busy while insuring that a virtual computer system 64a-64n hosting a safety-critical or real-time OS 70a-70n has the necessary level of support from the physical resources of the hardware platform 30. Typically, the individual OS's 70a-70n and applications 76a-76n running on the virtual computer systems 64a-64n may be isolated from each other by the hypervisor 40. That is, the operation of one of the OSs 70a-70n or one of the applications 76a-76n will not be able to affect the operation of another of the OSs 70a-70n or another of the applications 76a-76n hosted by a separate one of the virtual computer systems 64a-64n. This might allow, for example, one of the individual OSs 70a-70n to be rebooted without affecting the other OS's 70a-70n supported by the same hardware platform 30. The hypervisor 40 may thereby provide the plurality of secure virtual computer systems 64a-64n, which reduces the need for multiple physical computers that operate at different security levels but that are not fully utilized. The virtualized computer environment provided by the hypervisor 40 may thereby improve security and provide better resource utilization in comparison with conventional systems running multiple applications on a single hardware platform in the absence of a hypervisor.

The isolation provided by virtualization may also allow multiple versions of the same OS 70a-70n and/or the same application 76a-76n to run

simultaneously on the same hardware platform 30. This feature may allow testing of beta software legacy applications while the legacy application continues to be hosted on the same shared hardware platform 30. System developers may thereby test new releases of software without the need for dedicated test machines. If the beta software under test corrupts one of the OSs 70a-70n in a particular one of the virtual computer systems 64a-64n, another one of the OSs 70a-70n hosted on the same shared hardware platform 30 by the hypervisor 40 may be used to continue development of the beta software or to operate the wind turbine generator 100. In addition,

virtualization can help extend support for legacy applications and operating systems to new hardware, thereby extending the lifetime of the legacy software. By hosting both legacy and new operating systems with the hypervisor 40 on the same shared hardware platform 30 or embedded controller (e.g., Windows XP and Windows 7), engineers can reuse legacy applications and reduce the need to port programs to different operating systems.

As will be appreciated by one skilled in the art, the embodiments of the invention may also be embodied in a computer program product embodied in at least one computer readable storage medium having computer readable program code embodied thereon. The computer readable storage medium may be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof, that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. Exemplary computer readable storage media include, but are not limited to, a hard disk, a floppy disk, a random access memory, a read-only memory, an erasable

programmable read-only memory, a flash memory, a portable compact disc read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof. Computer program code for carrying out operations for the embodiments of the present invention may be written in one or more object oriented and procedural programming languages.

The methods described herein can be implemented by computer program instructions supplied to the processor of any type of computer to produce a machine with a processor that executes the instructions to

implement the functions/acts specified herein. These computer program instructions may also be stored in a computer readable medium that can direct a computer to function in a particular manner. To that end, the computer program instructions may be loaded onto a computer to cause the performance of a series of operational steps and thereby produce a computer implemented process such that the executed instructions provide processes for

implementing the functions/acts specified herein. It should be noted that the terms "connect" and "connection" are meant to be understood in their broadest sense so as to denote any relevant connection between the components, e.g., mechanical connections, such as shafts and alignment systems, load applying means, drive means, means for cooling and/or heating, electrical connections, data connections, such as control and/or signal transmission connections, interface connections for heating and/or cooling. Although the present invention has been described in connection with the specified embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. In the claims, the term "comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second" etc. do not preclude a plurality. Furthermore, reference signs in the claims shall not be construed as limiting the scope.

Claims

1 . A wind power computer system (50) comprising a first computer system (10) with a first operating system (OS1 ) and a second computer system (20) with a second operating system (OS2), characterized in that the first computer system (10) and the second computer system (20) are managed by a single computer hardware platform (30), the wind power computer system (50) further comprising a hypervisor (40) arranged for allowing the first and the second operating systems (OS1 , OS2) to share the computer hardware platform (30) as virtually separate computer systems.

2. A wind power computer system (50) according to claim 1 , wherein the first computer system (10) is arranged for controlling the wind power system, and the second computer system is arranged for monitoring the wind power system.

3. A wind power computer system (50) according to claim 1 or 2, wherein each of the first and second computer systems (10, 20) is a real-time computer system, a non-real time computer system, or a real-time computer system.

4. A wind power computer system (50) according to claim 3, wherein the first computer system (10) is different than the second computer system (20).

5. A wind power computer system (50) according to claim 1 wherein the hypervisor (40) comprises a plurality of virtual computer systems (64a-64n) that emulate physical resources compatible with an associated one of a plurality of OSs (70a-70n), and a hypervisor (40) configured to provide virtual resources (65-68) comprising the plurality of virtual computer systems (64a-64n).

6. A wind power computer system (50) according to claim 5 wherein at least one of the OSs (70a-70n) is a general purpose operating system, and at least another one of the OSs (70a-70n) is a real-time operating system.

7. A wind power computer system (50) according to claim 6 wherein the virtual computer system with the general purpose operating system further comprises an application (76a-76n) that is non-real-time.

8. A wind power computer system (50) according to claim 6 wherein the virtual computer system with the real time operating system further comprises an application (76a-76n) that is real-time or safety-critical.

9. A wind power computer system (50) according to any of the claims 1 to 8 wherein the wind power computer system (50) is a computer system within a wind power plant control system arranged to control and/or monitor the operation of a plurality of wind turbine generators in a wind power plant.

10. A method of operating a wind power computer system (50), the method comprising:

creating a first virtual computer system (64a-64n) hosted on a computer hardware platform (30) of the wind power computer system (50) using a hypervisor (40);

creating a second virtual computer system (64a-64n) hosted on the computer hardware platform (30) of the wind power computer system (50) using the hypervisor (40);

hosting a first operating system (70a-70n) on the first virtual computer system (64a-64n); and

hosting a second operating system (70a-70n) on the second virtual computer system (64a-64n), wherein the hypervisor (40) is configured to allow the first and second operating systems (70a-70n) to share the computer hardware platform (30) as virtually separate computer systems.

1 1 . The method according to claim 10, wherein the first operating system (70a-70n) is a real time operating system, and the second operating system

(70a-70n) is a general purpose operating system.

12. The method according to claim 10 or 1 1 , wherein the first virtual computer system (64a-64n) is configured to control the wind power system, and the second virtual computer system (64a-64n) is configured to monitor the wind power system.

13. The method according to claim 10 wherein each of the first and second virtual computer systems (64a-64n) is a real-time computer system, a non-real time computer system, or a real-time computer system

14. The method according to claim 13 wherein the first virtual computer system (64a-64n) is different than the second virtual computer system.

15. A computer program product comprising:

a computer readable storage medium; and

program instructions for performing the method of claim 10,

wherein the program instructions are stored on the computer readable storage medium.