Monitoring and fault prediction in relation to a mechanical component of a rotating system

Abstract

The present invention relates to a system configured to monitor a condition of a rotating system comprising a main bearing, the monitoring arrangement having a first measurement device configured to be arranged at a first location in proximity of the main bearing for determining a first measurement indicative of a current flow at the first location, and a control unit connected to the measurement device. The control unit is further configured to form a first parameter based on the first measurement, match the first parameter with a plurality of predetermined current flow profiles, each of the plurality of predetermined current flow profiles being indicative of a condition of the rotating system, determine, if a matching current flow profile is found, a relevance level for the corresponding condition, and provide an indication of an alarm if the relevance level is above a predetermined threshold.

Claims

1. A monitoring arrangement configured to monitor a condition of a wind mill or wind turbine having a main bearing, the monitoring arrangement comprising: a first measurement device at a first location on a first side of the main bearing that determines a first measurement indicating a current flow at the first location; a second measurement device at a second location on a second side of the main bearing, the second side is an opposite side of the first side, that determines a second measurement indicating a current flow at the second location; and a control unit connected to the first measurement device and the second measurement device, wherein the control unit is further configured to: form a first parameter based on the first measurement and the second measurement; match the first parameter with a plurality of predetermined current flow profiles, each of the plurality of predetermined current flow profiles being indicative of a condition of the main bearing; determine, if a matching current flow profile is found within the plurality of predetermined current flow profiles, a relevance level for the corresponding condition; provide an indication of an alarm if the relevance level is above a predetermined threshold; and predict the main bearing failure of the wind mill or wind turbine based on the matching current flow profile and historically matched current profiles for the corresponding condition.

2. The monitoring arrangement according to claim 1, wherein the first parameter is determined based on a difference between the first and the second measurement corresponding to a current flowing through the main bearing.

3. The monitoring arrangement according to claim 2, wherein the wind mill or wind turbine includes a main shaft and at least one of the first and the second measurement device includes a coil configured to be arranged around the main shaft of the wind mill or wind turbine.

4. The monitoring arrangement according to claim 1, wherein the control unit is further configured to receive status information relating to the wind mill or wind turbine, including at least one of a rotational speed of the main shaft and an operational mode of the wind mill or wind turbine.

5. The monitoring arrangement according to claim 4, wherein the predetermined current flow profiles are dynamically updated depending on the operational mode of the wind mill or wind turbine.

6. The monitoring arrangement according to claim 5, wherein the control unit is arranged remotely from the wind mill or wind turbine, connected to at least one of the first and second measurement device via a network.

7. The monitoring arrangement according to claim 6, wherein the control unit is comprised in a management server.

8. A method for monitoring a condition of a wind mill or wind turbine having a main bearing, by a control unit, comprising: arranging a first measurement device at a first location on a first side of the main bearing that determines a first measurement indicating a current flow at the first location; arranging a second measurement device at a second location on a second side of the main bearing, the second side is an opposite side of the first side, that determines a second measurement indicating a current flow at the second location; receiving, by the control unit, the first measurement; receiving, by the control unit, the second measurement; forming, by the control unit, a first parameter based on the first measurement and the second measurement; matching, by the control unit, the first parameter with a plurality of predetermined current flow profiles, each of the plurality of predetermined current flow profiles being indicative of a condition of the main bearing; determining, by the control unit, if a matching current flow profile is found within the plurality of predetermined current flow profiles, a relevance level for the corresponding condition; providing, by the control unit, an indication of an alarm if the relevance level is above a predetermined threshold; and predict the main bearing failure of the wind mill or wind turbine based on the matching current flow profile and historically matched current profiles for the corresponding condition.

9. The computer-implemented method according to claim 8, further comprising: determining a difference between the first measurement and the second measurement corresponding to a current flowing through the main bearing; and forming the first parameter based on the difference between the first measurement and the second measurement.

10. A system comprising: a first measurement device at a first location on a first side of the main bearing that determines a first measurement indicating a current flow at the first location; a second measurement device at a second location on a second side of the main bearing, the second side is an opposite side of the first side, that determines a second measurement indicating a current flow at the second location; and a management server comprising a processor and a non-transitory memory storing program instructions for monitoring a wind mill or wind turbine having a main bearing thereon, the program instructions executable by the processor to cause the management server to: receive the first measurement; receive the second measurement; form a first parameter based on the first measurement and the second measurement; match the first parameter with a plurality of predetermined current flow profiles, each of the plurality of predetermined current flow profiles being indicative of a condition of the main bearing; determine, if a matching current flow profile is found within the plurality of predetermined current flow profiles, a relevance level for the corresponding condition; provide an indication of an alarm if the relevance level is above a predetermined threshold; and predict the main bearing failure of the wind mill or wind turbine based on the matching current flow profile and historically matched current profiles for the corresponding condition.

11. The management server according to claim 10, further configured to determine a difference between the first measurement and the second measurement corresponding to a current flowing through the main bearing; and form the first parameter based on the difference between the first measurement and the second measurement.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing at least one example embodiment of the invention, wherein:

(2) FIG. 1a is a schematic illustration of an exemplary monitoring arrangement arranged in a rotating system, and FIG. 1b provides a detailed view of the control unit of such a monitoring device;

(3) FIG. 2 provides an illustration of a wind farm managed using a management server according to a currently preferred embodiment of the invention; and

(4) FIG. 3 is a flow chart illustrating the method steps of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(5) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.

(6) Referring now to the drawings and to FIG. 1a in particular, there is depicted a schematic illustration of portions of an exemplary rotating system, such as a wind turbine 100 where a measurement method and system according to the present invention may be used. The wind turbine illustrated in FIG. 1 a hub 102, a plurality of blades 104a-c connected to the hub 102, at least one pitch control motor (not shown) arranged at the hub 102 for controlling the pitch of the blades 104a-c, a main shaft 106 attached to the hub 102 and enclosing cabling for providing electrical power to the pitch control motors, a bearing housing 108 attached to a metallic structure 118 acting as electrical earth, and a main bearing 110 having an inner ring attached to the main shaft 106 and an outer ring attached to the bearing housing 108.

(7) A measurement arrangement for detecting an electric current through a main bearing of a rotating system is here shown comprising a first and a second measurement device, each in the form of a coil for measuring current, 114 and 116 arranged around the main shaft 106 on either side of the main bearing 110. Both coils 114 and 116 are electrically connected to a control unit 120 and the coils may for example be Rogowski-type coils. An alternating electric current in the main shaft 106 will induce a voltage in the coils 114 and 116 as the voltage induced in a coil is proportional to the derivative of the electric current in the main shaft 106. The voltage induced in the coils is received by the control unit 120 where it is integrated in order to represent the electric current through the main shaft 106 in the form of a waveform (representing the current flow).

(8) Turning now to FIG. 1b providing a detailed view of a control unit 120 comprised with the measurement arrangement. The control unit 120 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control unit 120 may also, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit 120 includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

(9) The control unit 120 additionally comprises a communication interface for allowing wired and/or wireless communication with e.g. a management server 202 remotely located away from the wind turbine 100 and arranged to manage a plurality of wind turbines of e.g. a wind farm 200, with further reference to FIG. 2. The communication between the control unit 120 and the remotely arranged management server 202 may for example be implemented by using mobile or non-mobile communication protocols, IP based protocols, and combinations of these and further protocols, for example over the Internet 204.

(10) The control unit is preferably further configured to receive extended information from a plurality of components of the wind turbine 100 and thereto related sensors, including for example information relating to wind speed/direction, outside temperature, vibration, moisture level, etc. The control unit 120 is in turn configured to process and correlate the extended information with information relating to the measurement provided my means of the first and optionally the second measurement devices for determining a condition of the wind turbine to for example be transmitted to the remotely located management server 202. Different information may be extracted from the determined condition. For example, based on the observation of an increasing current flow, it could be possible to predict moisture effects on cables used for controlling the pitch motors of the wind turbine 100. Also, it could be possible to get indications as to electrical issues of the wind turbine 100 including for example issues relating to ground loops of the wind turbine 100 or parts of the wind turbine 100. Other electrical issues may in a similar manner be extracted from the determined condition.

(11) Furthermore, the management server 202 may in turn be remotely accessed using for example a computer 206 having a thereto provided user interface, where the computer 206 is connected to the management server 202 over the Internet 204.

(12) During operation of the measurement arrangement, with further reference to FIG. 3, a first measurement is received, S1, from the first measurement device 114. Based on the first measurement, a first parameter is formed, S2, and then matched, S3, with a plurality of predetermined current flow profiles. If a matching current flow profile is found, a relevance level may be determined, S4. If the relevance level is above a predetermined threshold, an indication of an alarm is provided, S5.

(13) In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

(14) The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. For example, even though the embodiments disclosed above relates to the detection of AC current in a main shaft in a wind turbine application, it is equally possible to provide measurement devices for detecting direct currents in a main shaft for example in a marine application. Although pitch control is used in many ships, stray current issues for ships may more often be related to the use of dissimilar materials in an electrolyte (sea water).

(15) The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.