COMPONENT FIELD OF THE INVENTION

The present invention relates generally to wind power generation systems and, more specifically, to a device and method for testing a wind power plant component.

BACKGROUND OF THE INVENTION

A utility-scale wind energy system or wind power plant includes a group of wind turbines that operate collectively as a power plant to produce electrical energy without the consumption of fossil fuels. The electricity produced by the wind turbines is provided to the electrical grid, which distributes the generated electricity to power grid customers based on demand. The wind power plant thus reduces the amount of power which must be generated by traditional means by supplying a portion of the total power demand of the electrical grid.

A typical wind turbine includes a rotor mounted to a nacelle disposed at the apex of a tower and housing a generator. The rotor typically includes a plurality of blades that capture wind currents to produce rotation of the wind turbine. The rotor thereby converts wind energy into rotational energy. This rotational energy is coupled to the generator, which converts the rotational energy into electricity. The rotor blades will typically have an adjustable pitch that is set by a wind turbine controller in response to wind conditions. The wind turbine controller monitors the speed of the rotor and adjusts the pitch of the rotor blades in response to existing wind conditions in order to maximize the output of the wind turbine and to maintain the speed and torque applied to the generator at or below rated levels.

The power produced by the wind turbine is typically coupled to the grid through a power converter that converts the electrical output of the wind turbine generator into AC voltages suitable for use on the grid. The power converter operates under the control of a power controller, which adjusts the frequency, phase angle, and voltage of the power converter output as required to adjust the amount of real and reactive power transferred from the wind turbine generator to the grid. To store excess power production for release to the grid during times of low wind production, an energy storage system, such as a battery, may be coupled to the power converter.

The outputs of the wind turbine power converters are typically ganged together in parallel and connected to the grid at a single connection point. These connections will typically include circuit breakers to prevent damage to wind power plant and/or electrical grid components in the event of a power surge or other system disruption. The power controller function may be provided by a subsystem at each individual wind turbine, but may also be controlled, at least in part, by a centralized wind power plant controller. The centralized power plant control function monitors and controls individual wind turbine power converter outputs to provide power output levels that take into account both wind conditions at the individual wind turbine as well as system wide

conditions, such as electrical grid demands. The power plant controller may also control the operation of a reactive compensator to adjust the reactive power supplied to the grid at the wind power plant level.

A utility scale wind power plant thus includes multiple subsystems that control the operation of the various components of the power plant, such as electrical grid monitors, wind turbine controllers, power converter controllers, energy storage system controllers, circuit breaker controllers, and a power plant controller. These subsystems monitor wind power plant and grid conditions to provide control mechanisms that optimize the power output of the wind power plant. The wind power plant subsystems also include safety mechanisms that prevent wind turbines, power converters, and other plant systems from operating outside of their maximum allowable design parameters. To this end, the wind power plant subsystems monitor grid and wind power plant

operational parameters, and condition the power generated by the wind turbines so that the power is safely provided to the electrical grid in

conformance with grid codes.

The aforementioned wind power plant subsystems interact in complex fashion so that changes in one subsystem can affect the overall performance of a wind power plant in unexpected ways. In addition, the variable nature of both wind power availability and electrical grid demands further increase the potential for undesirable and unexpected results when wind power plant subsystems or components of the wind power plant are added, removed, or otherwise modified. Testing of new or modified power plant components and

configurations by simply placing these components and configurations in service and observing the results thus introduces undesirable expenses and risks into the operation of the wind power plant.

Accordingly, there is a need for a device and a method which allow testing of power plant components and system modifications before they are

implemented avoid introducing undesirable components and modifications into wind power plants. SUMMARY OF THE INVENTION

It is an object of the invention to improve the testing of wind power plant components.

The method according to an embodiment of the invention is a method of testing a wind power plant controller. The controller is configured to receive signals from and transmit signals to wind turbines in a wind power plant. The testing method includes: (1 ) connecting the wind power plant controller to a test device. The test device includes one or more subsystem simulators. At least one subsystem simulator is arranged to simulate a certain wind power plant subsystem or conditions influencing wind turbines in a wind power plant; and (2) testing the wind power plant controller by performing a simulation via the subsystem simulators.

Program instructions for performing the aforementioned method may be implemented in a computer program product. The program instructions are stored on a computer readable storage medium. The device according to an embodiment of the invention is a test device for testing a wind power plant component. The test device includes an interface for connecting a wind power plant controller to the test device and one or more subsystem simulators. Each of the one or more subsystem simulators is configured to simulate an associated wind power plant subsystem or condition.

When the wind power plant control system is connected to simulators which will simulate the behavior of the electrical grid and/or the turbines in the wind farm power plant, it becomes possible to execute real time control using the proper wind power plant controller prior to implementation thereof on a grid. 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 shows a schematic drawing of a wind power plant;

Figure 2 shows a schematic drawing of a test device for testing a wind power plant controller;

Figure 3 shows a schematic drawing similar to Figure 2 that further includes a test measurement simulator; and Figure 4 is a flow chart of a method according to the invention.

DETAILED DESCRIPTION

Referring now to Figure 1 , a wind power plant 10 includes a wind power plant controller (WPP) 20, a plurality of wind turbines represented by wind turbines 30, 31 , 32, 33, and optional reactive power compensation equipment 40. The wind turbines 30-33 are connected via radials 36, 37, 38, 39 and switches 50, 51 to common connection points where the power output of the wind power plant 10 is coupled to one or more electric grids 60, 61 . The wind power plant 10 as illustrated also includes a switch 52 that connects a first group of wind turbines 30, 31 and a second group of wind turbines 32, 33 within the wind power plant 10. The first and second groups of wind turbines may be ganged together by closing the switch 52 so that the wind power plant 10 collectively provides a composite power output to the one or more electrical grids 60, 61 . By opening the switch 52, the first and second groups of wind turbines may be electrically isolated from each other. This isolation allows the wind power plant 10 to provide power to the grids 60, 61 as two electrically separate wind power plants using only a subset of the available wind turbines 30-33 under the control of the wind power plant controller 20 to supply power to each grid 60, 61 . The switches 50-52 are typically not operated directly by the wind power plant controller 20. However, feedback signals relating to the status and/or position of the switches are typically provided to the wind power plant controller 20 to allow the controller 20 to factor in the state of the switches 50-52 as a parameter for controlling the operation of the wind power plant 10.

The wind power plant controller 20 provides control signals to the wind turbines 30-33 in the form of power set points such as, but not limited to, the desired active and/or reactive power output to be supplied from the individual wind turbines 30-33. These set points and control signals may be used by the wind turbine power controller 20 to adjust the power output of the wind turbines 30- 33. To provide plant level control of the reactive power supplied to the grid 60, 61 , the wind power system controller 20 may be operatively coupled to the optional compensation equipment 40, which may be configured to adjust the amount of reactive power provided to the grid using known methods. The wind power system controller 20 may thereby regulate the active and reactive power provided to the electrical grid 60, 61 by adjusting the individual power output levels of each wind turbine 30-33, and/or by adjusting the reactive power of the wind power plant 10 at a plant level.

To this end, the wind power plant controller 20 may obtain measurements of the active and reactive power supplied to the electrical grid 60, 61 , as indicated by arrowed line 4. From these power measurements, the wind power plant controller 20 calculates new power set points and other control signals, as appropriate, to be supplied to the wind turbines 30-33 and other power control equipment, such as the compensation equipment 40 and the switches 50-52. The wind power plant controller 20 transmits these set points and other control signals to the appropriate components and subsystems of the wind power system 10 as indicated by arrowed line 5. In response to the control signals 5, the wind power plant components and subsystems may react by adjusting the power output of the wind turbines 30-33 and wind power system 10 as indicated by arrowed line 6. Although only four wind turbines are shown in Figure 1 it should be understood that the wind power plant 10 may comprise a smaller or larger number of wind turbines 30-33. For example, a large wind power plant 100 might include over 100 wind turbines 30-33. Moreover, it is not mandatory that the wind power plant includes compensation equipment 40, in which case the wind power plant controller 20 may control the composite power output of the wind power plant 10 by controlling the power output of the wind turbine power converters.

Referring now to Figures 2 and 3, a schematic drawing illustrating a test device or system 500 for testing a wind power plant controller 20 is presented. The test device 500 comprises a simulator system that includes subsystem simulators in the form of a wind turbine simulator 530, a reactive compensation equipment simulator 540, a circuit breaker simulator 550, a grid simulator 560, a wind simulator 570, a cabling system simulator 575 that simulates the cabling system within the wind power plant 10, an energy storage simulator 580, and/or a supervisory control and data acquisition (SCADA) system simulator 585. Figure 2 illustrates one embodiment in which a grid measurement subsystem 565 is shown outside the test device 500, while Figure 3 illustrates an alternative embodiment in which a grid measurement subsystem is

implemented as a software algorithm within the test device 500. The grid measurement subsystem as illustrated in Figure 3 is thereby implemented as a grid measurement simulator 566.

To provide the test device 500 with accurate models on which to base wind power plant simulations, the subsystem simulators may include data on real- world subsystem performance over a range of environmental conditions. For example, the wind turbine simulator 530 may include the operation of one or more specific models of wind turbines over a range of operating conditions, including a range of wind speeds. Similarly, the reactive compensation equipment simulator 540 may include simulation of reactive compensation equipment, such as a STATCOM or capacitor banks. The grid simulator 560 may include a range of possible grid operation conditions, including faults in the grid, low voltage ride through situations, frequency fluctuations, inclusion of large loads in the grid, etc. The wind simulator 570 may include simulation of a range of different wind conditions, e.g. wind speed, gusts, wind shear, turbulence, etc. The cabling system simulator 575 may include the electric properties of the cables within the wind power plant 10, such as the impedance of the cables. The energy storage simulator 580 may include properties of an energy storage system within or in conjunction to the wind power plant 10, including the charging state of the energy storage system. The simulated energy storage system might include a battery, a flywheel or other suitable power storage equipment.

The test device 500 may include a control interface 590 that connects the wind power plant components to the associated subsystem simulators. The control interface 590 may thereby allow the subsystem simulators to exchange data with their associated wind power plant subsystems. For example, the wind turbine simulator 530 may obtain operational data from the wind power plant controller 20 related to the operation of the wind turbines 30-33. This data may be used to modify the wind turbine simulator 530 so that it more accurately predicts the behavior of the wind turbines 30-33 as configured in the wind power plant 10. Likewise, data generated by the wind turbine simulator 530 may be provided to the wind power plant controller 20 to improve, control, or otherwise modify the performance of the controller 20. The grid simulator 560 may exchange data with the grid measurement subsystem 565, whether implemented external to the test device 500 (Figure 2) or, alternatively, within the test device 500 as a grid measurement simulator 566 (Figure 3) to improve the performance of the grid simulator 560.

When the wind power plant controller 20 is connected to simulators that simulate the behavior of the electrical grid 60, 61 and/or the wind turbines 30- 33 comprising the wind power plant 10, it becomes possible to execute real time control using the proper wind power plant controller 20 prior to

implementation thereof on a grid. Advantageously, the test device 500 provides the ability to conduct realistic simulations of wind power plant control strategies and control system under various scenarios which would be difficult, expensive, dangerous, and/or otherwise undesirable to create as a real-world test. The test device 500 thereby provides a virtual laboratory that renders it possible to perform realistic testing of the wind power plant control systems in various scenarios even before the wind power plant 10 is built. The test device 500 thus provides the ability to demonstrate wind power plant control system capabilities prior to implementation. Moreover, the test device 500 facilitates testing of the wind power plant controller 20 in the case of fluctuations or faults on the electrical grid, e.g., a low voltage ride through (LVRT) or frequency deviations.

As an example of how the test device 500 might provide a wind power plant simulation using data provided by the subsystem simulators, the output from the wind simulator 570 may be provided the wind turbine simulator 530 to generate wind turbine operational scenarios based on probable or extreme wind conditions at the wind power plant 10. Likewise, signals may also be exchanged between the circuit breaker simulator 550, grid simulator 560, cabling system simulator 575, energy storage simulator 580, and wind turbine simulator 530 based on historical and/or expected behavior of related wind power plant components and the grid 60, 61 . Signals may also be

exchanged between the grid simulator 560, the grid measurement subsystem 565 or grid measurement simulator 566, as well as between the grid simulator 560 and the circuit breaker simulator 550. Signals may also be exchanged between the grid measurement subsystem 565 and/or simulator 566, between grid measurement subsystem 565 and/or simulator 566 and the wind turbine simulator 530 as well as between the wind power plant controller 20 and the reactive compensation equipment simulator 540 and SCADA simulator 585.

The invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention or some features of the invention can be implemented as computer software running on one or more data processors and/or digital signal processors. The elements and components of embodiments of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit, or may be physically and functionally distributed between different units and processors.

Thus, the simulator subsystems may be implemented as different computer software algorithms running on one or more data processors. For example, as shown in Figure 2, the grid measurement subsystem 565 resides outside the test device 500. The grid measurement subsystem 565 may be a hardware grid meter connectable to the wind power plant controller 20 as well as to the test device 500 for testing the wind power plant controller 20. In an alternative embodiment of the invention, the grid measurement subsystem 565 may be implemented as a software algorithm within the test device 500 that provides a grid measurement simulator 566 as illustrated in Figure 3.

Referring now to Figure 4, a flow chart of a method 100 of testing the wind power plant controller 20 according to an embodiment of the invention is presented. The wind power plant controller 20 is configured to receive signals from and transmit signals to wind turbines 30-33 in the wind power plant 10.

In block 102 the wind power plant controller 20 is connected to the test device 500. As described with respect to Figure 2, the test device 500 may include a plurality of subsystem simulators that each represents a component or subsystem of the wind power plant 10. Each subsystem simulator is thereby arranged to simulate a certain wind power plant subsystem or conditions influencing the wind turbines 30-33 in the wind power plant 10. Once the test device 500 has been configured to model the subsystems of the wind power plant 10, the method 100 proceeds to block 103.

In block 103, the wind power plant controller 20 is tested by performing a simulation via the subsystem simulators and by registering the performance of the wind power plant controller 20 as a function of the simulations. The results of the simulations from the test device 500 may be used to adjust parameters within the wind power plant controller 20 to optimize the performance of the wind power plant 10, to predict the effect of changes to subsystems within the wind power plant 10, or to control the wind power plant 10. Different configurations and environmental scenarios may thereby be tested with regard to the wind power plant 10 by modeling the wind power plant 10 in the test device (500).

It should be noted that as used herein, the term "wind power plant" is synonymous to "wind farm" and "wind park" and is meant to denote a plurality of wind turbines as well further units, equipment, or subsystems, as

appropriate, such as a power plant controller and/or compensation equipment.

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. Such computer program instructions may also be provided through a computer based network, e.g., the Internet.

The elements and components of embodiments of the invention may be physically, functionally and logically implemented in any suitable way. For example, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the invention may be implemented in a single unit, or may be physically and functionally distributed between different units and processors.

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 features 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 of embodiments of the invention.