WIND TURBINE HAVING AN ELECTRICAL POWER GENERATION ASSEMBLY AND METHOD FOR DETECTING A FAULT CONDITION IN SUCH A WIND TURBINE

Abstract

A wind turbine having an electrical power generation assembly and a control device for controlling the power generation assembly is provided, the electrical power generation assembly including a generator, at least one converter connected to the generator, and an overheating detection device, wherein the overheating detection device includes—at least two temperature sensing elements at different positions of the power generation assembly, wherein the temperature sensing elements are connected in series along a signal line to provide a common sensor signal and are each adapted to indicate the exceeding of a respective critical temperature at their position in the common sensor signal, and—a detection unit for evaluating the common sensor signal, which is connected to the signal line.

Claims

1. A wind turbine having an electrical power generation assembly and a control device for controlling the power generation assembly, the electrical power generation assembly comprising a generator, at least one converter connected to the generator, and an overheating detection device, wherein the overheating detection device comprises; at least two temperature sensing elements at different positions of the power generation assembly, wherein the temperature sensing elements are connected in series along a signal line to provide a common sensor signal and are each adapted to indicate the exceeding of a respective critical temperature at their position in the common sensor signal; and a detection unit for evaluating the common sensor signal, which is connected to the signal line.

2. The wind turbine according to claim 1, wherein the detection unit or the control device of the wind turbine, to which the detection unit is connected, is adapted to execute at least one measure if an exceeding of at least one of the critical temperatures is detected in the common sensor signal.

3. The wind turbine according to claim 1, wherein the temperature sensing elements are PTC thermistors, wherein a transition temperature of the switching PTC thermistor is the critical temperature.

4. The wind turbine according to claim 3, wherein the detection unit comprises a resistance measuring circuit for measuring the resistance of the temperature sensing elements along the signal line.

5. The wind turbine according to claim 1, wherein the power generation assembly comprises phase connectors to connect to the at least one converter, wherein a temperature sensing element is positioned at each phase connector.

6. The wind turbine according to claim 5, wherein three phase connectors are provided for each converter and/or the power generation assembly comprises multiple converters.

7. The wind turbine according to claim 5, wherein the critical temperature for each connector is 90° C. to 200° C.

8. The wind turbine according to claim 5, wherein the connectors are bus bars.

9. The wind turbine according to claim 1, wherein the generator further comprising, at its hottest position, at least one temperature sensor for measuring a temperature value, wherein the temperature sensor is connected to the control device.

10. The wind turbine according to claim 1, wherein the detection unit comprises a box-like housing and is directly by a connector of the housing, connected to the control device.

11. A method for detecting a fault condition in a power generation assembly of a wind turbine according to claim 1, wherein the common sensor signal is evaluated at least in the detection unit and, if the common sensor signal indicates an exceeding of the critical temperature at at least one position of a temperature sensing element, at least one measure is executed by the detection unit and/or the control device.

12. The method according to claim 11, wherein at least one of the at least one measure comprises outputting an alarm signal to an external output device at a manufacturer of the wind turbine and/or a maintenance service.

13. The method according to claim 11, wherein at least one of the at least one measure comprises deactivating and/or disconnecting at least a subsystem of the generator.

Description

BRIEF DESCRIPTION

[0026] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0027] FIG. 1 shows a principle drawing of a wind turbine according to embodiments of the invention;

[0028] FIG. 2 shows a schematical drawing of the electrical power generation assembly of the wind turbine; and

[0029] FIG. 3 shows a resistance-temperature-diagram of a PTC thermistor.

DETAILED DESCRIPTION

[0030] FIG. 1 is a principle drawing of a wind turbine 1 according to embodiments of the invention. The wind turbine 1 comprises a tower 2 carrying a nacelle 3 with a hub 4, to which at least two wind turbine blades 5 are mounted. An electrical power generation assembly 5 is housed in the nacelle 3, which comprises a generator 6 and multiple converters 7, from which for reasons of clarity only one is shown in FIG. 1. The generator 6 is connected to each of the converters 7 by three electrical connections 8, one for each of the three phases used. For example, the generator 6 may comprise subsystems which are connected to certain converters 7. In an example, the power generation assembly 5 may comprise twelve converters. The operation of the wind turbine 1, in particular also the power generation assembly 5, is controlled by a control device 9, sometimes called “controller”.

[0031] The wind turbine 1 may be a direct drive wind turbine or may comprise a gear box housed in the nacelle 3.

[0032] In any case, the power generation assembly 5 further comprises an overheating detection device 10, which is used to monitor the electrical connections 8 with regard to thermal effects caused by phase unbalance, for example by disconnection of at least one electrical connection 8.

[0033] The overheating detection device 10 will be described in more detail with reference to FIG. 2. As shown in FIG. 2, the generator 6 is connected to the converters 7 by phase connectors 11, in this case bus bars. On each of the bus bars, a temperature sensing element 12, in this embodiment a PTC thermistor 13, is positioned.

[0034] FIG. 3 shows a resistance-temperature-diagram for a PTC thermistor 13, wherein the resistance is shown on a logarithmic scale. As can be seen, the PTC thermistor 13 may have a slightly negative temperature coefficient up to a point of minimum resistance R.sub.min, from which point a slightly positive temperature coefficient occurs up to the transition temperature Tc. At this transition temperature, a steep rise of the resistance occurs. For example, the transition temperature may be defined as the temperature at which the resistance is twice the value of the minimum resistance, as exemplarily shown in FIG. 3.

[0035] In this embodiment, the transition temperature, which is equivalent to a critical temperature for the phase connectors 11, is in the interval of 90° C. to 200° C., for example 120° C. or 150° C.

[0036] Consequently, if the temperature of a respective phase connector 11 rises above the transition temperature Tc, the resistance of the PTC thermistor switches to a very high value, such that such PTC thermistors are also called switching-type PTC thermistors or simply switching PTC thermistors 13.

[0037] As can be seen from FIG. 2, the temperature sensing elements 12 are all connected in series along a signal line 14, which may be a simple wire or one-wire cable. The signal line 14 begins and ends at a detection unit 15, which comprises a resistance measuring circuit 16 for measuring the resistance along the signal line 14. For example, the voltage while enforcing constant current may be measured by the resistance measuring circuit. Obviously, if the critical temperature is exceeded for at least one of the PTC thermistors 13, the sensor signal along the signal line 14 will change, since the resistance along the whole signal line 14 will increase strongly. That is, all temperature sensing elements 12 share a common sensor signal, since the exact position where the critical temperature is exceeded is not required to be detected. In other words, the knowledge that overheating occurs at at least one of the phase connectors 11 is sufficient to conclude that a fault condition which requires maintenance is present.

[0038] The detection unit 15 may further comprise a microcontroller 17 for evaluating the common sensor signal, in this case processed to derive information which is then transmitted to connected control device 9. Such an overheating information may comprise the actually measured resistance, but in certain cases is a binary overheating signal, indicating if overheating is present (high resistance, in particular surpassing a threshold value) or not (low resistance).

[0039] If overheating is detected, an alarm signal is output to an external, distant output device, such that an alarm may be output at, for example, a manufacturer of the wind turbine and/or a maintenance service.

[0040] The overheating detection device 10 thus allows early detection of at least one disconnection event, such that, usually, disconnecting and/or deactivating the generator 6 or at least one subsystem of the generator 6 is not necessary, since enough time remains to resolve the fault condition, for example reconnect a disconnected phase connector 11.

[0041] It is noted that further thermal management may also be provided in the wind turbine 1, for example by using a temperature sensor 18, for example Pt100 sensor, at the hottest point of the generator 6 and possibly further positions. As can be seen, the overheating detection device 10 is restricted to the phase connectors 11. However, multiple overheating detection devices 10 for different subsets of phase connectors 11 may be provided, or even additional overheating detection devices 10 may be provided for other sets of positions and/or components of the power generation assembly 5.

[0042] Although the present invention has been disclosed in the form of embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0043] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.