Detection of a loose electrical connection in a wind turbine
Patent Information
- Application Number
- EP2024708208
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-04-11
- Filing Date
- 2024-03-01
- Publication Date
- 2025-12-24
AI Technical Summary
In wind turbines, loose electrical connections can go undetected due to inaccessibility, leading to potential damage or fire, as existing methods lack an efficient and automatic means for online detection.
A method involving a measuring wire with coiled loops around conductors to detect unequal current distribution by inducing a current through inductance, where the number of loops is selected to detect deviations below a threshold, indicating a loose connection.
Enables automatic and cost-effective online detection of loose connections, preventing damage and ensuring safe operation of wind turbines by identifying deviations in current distribution.
Smart Images
Figure EP2024055410_17102024_PF_FP_ABST
Abstract
Description
[0001] DETECTION OF A LOOSE ELECTRICAL CONNECTION IN A WIND TURBINE
[0002] FIELD OF THE INVENTION
[0003] The invention relates to the detection of a loose connection, or high-resistance connection, of conductors electrically connecting two electrical devices or systems . The invention is especially related to electrical devices within wind turbines .
[0004] BACKGROUND OF THE INVENTION
[0005] Wind turbines are positioned either onshore or of fshore . In either case , the electrical connections are not checked frequently, often due to the turbines being relatively inaccessible . It thus would be an advantage to have an automatic and / or online detection of a loose connection . This is also the case since due to the loads and conditions , a connection could get loose over time .
[0006] It therefore is an obj ect of the present invention to introduce cheap and easily introduced and replicable means and method to identi fy i f there is a loose connection of conductors , which otherwise could lead to damage of the devices or wind turbine itsel f , such as by fire .
[0007] SUMMARY OF THE INVENTION
[0008] The obj ect of the invention is achieved by the independent claims . The dependent claims describe advantageous developments and modi fications of the invention .
[0009] The solution includes introducing a method to measure i f there is substantially equal current in a plural of On conductors , the method including to arrange a measuring wire with a first direction coiling formed of N1 loops around a first of the conductors and a second direction coiling formed of N2 loops around a second of the conductors at the opposite looping direction relative to the first direction coiling, wherein number of loops N1 and N2 is selected such that the current induced in the measuring wire due to inductance by the currents in the conductors theoretically adds to value below a threshold T , and detect it as an inequality among the conductors i f the added measurement exceeds the threshold T , and the number Cnl of the first conductors are di f ferent from the number Cn2 of the second conductors .
[0010] In one embodiment the first and / or the second of the conductors are grouped into at least two sub-groups Cnla, Cnlb, Cn2a, Cn2b where each sub-group are looped by a subgroup Nla, Nib, N2a, N2b of the respective first direction coiling and / or second direction coiling .
[0011] The total sum of loops N1 of the first direction coiling' s may be such that it equals the total of sum of loops N2 of the second direction ceiling' s .
[0012] Each of the first and second direction loops may encircle the same number of conductors .
[0013] Each of the first and second direction loops may encircle a single conductor .
[0014] There may be double the number of first direction coiling' s compared to the number of second direction ceiling' s , and where the individual of the first direction coiling' s has hal f the number of loops as the individual second direction coiling' s .
[0015] There may be two first direction coiling' s and one second direction coiling .
[0016] Each first kind coiling may comprise two loops , and each second kind coiling comprises four loops . The method may be used to detect a loose connection of the conductors .
[0017] The conductors may be divided into groups of three , where for each group the tree conductors are connected with a measuring wire .
[0018] The aggregated number of loops N1 of the first may equal the aggregated number of loops N2 of the second direction coiling' s .
[0019] The solution further includes introducing a wind turbine comprising means to control i f there is substantially equal current in a plural of Cn conductors , the means including arrange a measuring wire arranged with a first direction coiling formed of N1 loops around Cnl of a first of the conductors and a second direction coiling formed of N2 loops around Cn2 of a second of the conductors at the opposite looping direction relative to the first direction coiling, wherein number of loops N1 and N2 is selected such that the current induced in the measuring wire due to inductance by the currents in the conductors theoretically adds to value below a threshold T , and detect it as an inequality among the conductors i f the added measurement exceeds the threshold T , and where the number Cnl of the first conductors are di f ferent from the number Cn2 of the second conductors .
[0020] The wind turbine may include the means for operating according to the method of any of the previous embodiments .
[0021] BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings , of which :
[0023] Figure 1 shows a general illustration of a wind turbine . Figure 2 shows a general illustration of the drive train within a wind turbine .
[0024] Figures 3A and B illustrates phase shi fted three-phase currents , where fig . 3A shows the currents adding to zero in an ideal system .
[0025] Figure 4 shows three conductors with a measuring wire formed with first direction coiling' s looping two of the conductors , and a second direction coiling looping the third conductor .
[0026] Figure 5 shows nine conductors divided into groups of three conductors , where for each group a measuring wire is formed with first direction coiling' s looping two of the conductors , and a second direction coiling looping the third conductor of the group .
[0027] Figure 6 shows nine conductors divided into groups of three conductors , where a measuring wire is formed with two first direction coiling' s each looping three of the conductors , and a second direction coiling looping the three remaining conductors .
[0028] The illustration in the drawings is in schematic form . It is noted that in di f ferent figures , similar or identical elements may be provided with the same reference signs .
[0029] DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 shows an embodiment wind turbine 1 positioned in the water, such as the ocean . The wind turbine 1 comprises a tower 2 mounted on a non-depicted fundament . A nacelle 3 is arranged on top of the tower 2 . The wind turbine 1 further comprises a wind rotor 5 having two , three or more blades 4 ( in the perspective of Figure 1 only two blades 4 are visible ) . The wind rotor 5 is rotatable around a longitudinal rotation axis Y . The wind turbine 1 comprises an electric generator .
[0031] Figure 2 schematically shows the principle of construction of the energy producing system of a wind turbine 1 showing a generator 1 connected to the rotor 5 by a shaft or drive train . A variable-voltage DC link with a capacitor is feed by the recti fied voltage pulses of the generator 1 , and an inverter 7 , for example a force-commutated inverter, is adapted to create a defined alternating output voltage . A trans former 8 brings the alternating voltage to a suitable peak level and frequency for feeding the energy into the utility grid 9 .
[0032] Figure 3A illustrates six conductors 10 connecting two devices 11 . The devices 11 could be any electrical systems or devices where power exchange is required . In one embodiment they could be respectively a generator 6 and inverter 7 in a wind turbine 1 , a wind turbine 1 in general to a grid 9 , an inverter 7 to the trans former 8 etc .
[0033] In the illustration six conductors 10 are illustrated though any number more than one conductor 10 would apply to the present invention .
[0034] In the illustration the conductors 10 are connected to the devices 11 trans ferring a total current split between the six conductors 10 . Ideally i f excluding any ef fects of current displacement due to asymmetrical magnetic field distribution, each thus will be carrying about the same fraction of the total current in the ideal situation with equal resistivities etc . In fig . 3A all conductors are correctly connected, but in fig . 3B one is loosely 12 or not fully connected forming a loose or high-resistivity connection . This could form a risk, e . g . , the current in the remaining conductors raising to a level where they could be heating possible to start a fire . Figure 4 illustrates a method to measure if there is substantially equal current in 3 conductors 10, though the method could be expanded to any number Cn of conductors 10, such as Cn = 1, 2, 3, 4, 5, 6 etc.
[0035] The method includes to arrange a measuring wire 20 with a first direction coiling 30 wrapped, og coiling, around a first of the conductors (10) and a second direction coiling 40 wrapped, or coiling, around a second of the conductors 10 at the opposite looping, or coiling, direction relative to the first direction coiling 30. The one of the first 30 and second 40 direction ceiling's thus could be looping, or coils, with N1 loops in a clockwise direction around the respective conductor 10, whereas the other of the first 30 and second 40 direction ceiling's then could be looping, or coils, with N2 loops in an anti-clockwise direction around the respective conductor 10.
[0036] In the illustration two first direction ceiling's 30 are seen each with two loops, and the single second direction coiling 40 are seen with four loops.
[0037] More generally, any number Cn ( = 1, 2, 3, 4, ...) of conductors would apply to the present invention, just as any number of respective first 30 and second 40 direction ceiling's.
[0038] The number of loops in the different first direction ceiling's 30 and the different second direction ceiling's 40 could also be different.
[0039] In general, the first and / or the second of the conductors (10) may be grouped into at least two sub-groups (10a, 10b) where each sub-group are looped by a sub-group (30a, 30b) of the respective first direction coiling (30) and / or second direction coiling (40) .
[0040] In the embodiment as seen in figure 4 and 5 there are two sub-groups (10a) of the first conductors (10) each with a single conductor (10) and each coiled with two loops N1 by the measuring wire 20. Correspondingly in the shown embodiment there is one sub-group (10b) of the second conductors (10) with a single conductor (10) and coiled by four loops N2.
[0041] In one embodiment, the number of loops Nl, N2 of the respective first 30 and second 40 direction ceiling's relates to the number of conductors 10 they respectively loop's or is wrapped around, the relation being such that the expected ideal current will be a fixed value close to or being zero. In the illustrated embodiment of fig. 1 the two first direction ceiling's 30 each is wrapped (or coils) around a single conductor 10 and each comprises Nl = 2 loops. The second direction coiling 40 is wrapped (or coils) around a single conductor 10 and each comprises N2 = 4 loops. In total, the aggregated, or total, number of loops Nl of the first 30 equals the aggregated, or total, number of loops N2 of the second 40 direction ceiling's, whereas the number of first conductors 10 are different from the number of first conductors. In the illustrated embodiment there are double the number Cnl of first of the conductors (10) compared to the number Cn2 of the second of the conductors (10) .
[0042] In general, as also indicated above, the relation is such that the number of loops Nl and N2 is selected for the current induced in the measuring wire 20 due to inductance by the currents in the conductors 10 theoretically too add to value below a threshold T. The method thus includes to detect it as an inequality among the conductors 10) if the added measurement exceeds the threshold T. In one embodiment T equals zero or is at least close to zero compared to the expected current of each conductor 10, such as less than 20%, or less than 10% or less than 5%.
[0043] The equation for the ideal situation taking only account on the currents within the conductors 10 and their induction of a current in the measuring wire 20, would then be: Iw = 2 x 130,1 + 2 x 130,2 - 4 x 140,
[0044] Where Iw is the current measured in the measuring wire 20, the parts 2 x 130,1 and 2 x 130, 2 is the two first 30 direction coiling' s each with two loops and the respective currents 130,1 and 130,2 in the conductors 10. The part 4 x 140 is the four loops of the second direction coiling 40 and the current 140 of the respective conductor 10. If all currents are equal, Iw will be zero, or close to zero. In a less ideal situation if Iw > T, where T is the defined threshold possible being zero, this is an indication of an inequality .
[0045] Figure 5 illustrates an embodiment with more than 3 conductors. In the illustration 9 conductors 10 are seen divided into groups of three. For each group the tree conductors 10 are connected with a measuring wire 20 according to the previous embodiments.
[0046] In the embodiment as seen there are two sub-groups (10a) of the first conductors (10) each with a single conductor (10) and each coiled with two loops N1 by the measuring wire 20. Correspondingly in the shown embodiment there is one subgroup (10b) of the second conductors (10) with a single conductor (10) and coiled by four loops N2.
[0047] Figure 6 shows an embodiment where there are more than 3 conductors, where, alternatively, or additionally, to forming groups of three each with a measuring wire 20 as in fig. 3, all or some of the first 30 and second 40 direction ceiling's are wrapped around a plural of conductors 10.
[0048] In this embodiment there are two sub-groups (10a) of the first conductors (10) each with three conductors (10) and each coiled with two loops N1 by the measuring wire 20. Correspondingly in the shown embodiment there is one subgroup (10b) of the second conductors (10) with three conductors (10) and coiled by four loops N2. In figure 6 each of the ceiling' s 30 , 40 loop the same number of conductors 10 . The number of loops Nl , N2 of the respectively first 30 and second 40 direction ceiling' s are the same as in e . g . fig . 4 , thus giving the same conditions .
[0049] A more general equation for the ideal situation taking only account on the currents within the conductors 10 and their induction of a current in the measuring wire 20 , would then be :
[0050] Iw = SmNlni x 130 , nl - En2 4 x 1 0 , n2
[0051] Where Iw is the current measured in the measuring wire 20 , the first part is the sum of the currents 130 , nl of the individual conductors 10 looped by first 30 direction ceiling' s multiplied with the respective loops Nlnl. In the same manner, the second part is the sum of the currents 140 , nl of the individual conductors 10 looped by second 40 direction coiling' s multiplied with the respective loops N2n2.
[0052] The respective number loops Nlnland N2n2of the individual conductors 10 and the number of first 30 and second 40 direction coiling' s are then selected such that in case of equality of currents in the conductors 10 the measuring wire 20 current Iw ideally will be zero , or at least close to zero .
[0053] In the embodiments as illustrated in e . g . any of figs . 4- 6 , the total sum of loops Nl of the first direction ceiling' s 30 equals the total of sum of loops N2 of the second direction coiling' s 40 .
[0054] Further, for the illustrated embodiments each of the first 30 and second 40 direction loops encircles the same number of conductors 10 . In some not illustrated embodiments the different ceiling's 30, 40 loop different number of conductors 10.
[0055] In general, one single measuring wire 20 thus loops, or coils, booth the first and second conductors 10. Further, the one single measuring wire 20 thus comprises an any relevant number of sub-groups (30a, 30b) of the respective first direction coiling (30) and / or second direction coiling (40) .
Claims
Patent Claims1. Method to measure if there is substantially equal current in a plural of Cn conductors (10) , the method including to arrange a measuring wire (20) with a first direction coiling (30) formed of N1 loops around Cnl of a first of the conductors (10) and a second direction coiling (40) formed of N2 loops around Cn2 of a second of the conductors (10) at the opposite looping direction relative to the first direction coiling (30) , wherein the number of loops N1 and N2 is selected such that the current induced in the measuring wire (20) due to inductance by the currents in the conductors (10) theoretically adds to value below a threshold T, and detect it as an inequality among the conductors (10) if the added measurement exceeds the threshold T, and the number Cnl of the first conductors are different from the number Cn2 of the second conductors.
2. method according to claim 1, wherein the first and / or the second of the conductors (10) are grouped into at least two sub-groups (10a, 10b) where each sub-group are looped by a sub-group (30a, 30b) of the respective first direction coiling (30) and / or second direction coiling (40) .
3. Method according to claim 1 or 2, wherein the total sum of loops N1 of the first direction ceiling's (30) equals the total of sum of loops N2 of the second direction coiling(40) .
4. Method according to claim 1, 2 or 3, wherein each of the first (30) and second (40) direction loops encircles the same number of conductors (10) .
5. Method according to any of claims 1-4, wherein each of the first (30) and second (40) direction loops encircles a single conductor (10) .
6. Method according to any of the preceding claims, wherein there are double the number of first direction ceiling's (30) compared to the number of second direction ceiling's (40) , and where the individual of the first direction coiling' s (30) has half the number of loops as the individual second direction ceiling's (40) .
7. Method according to claim 6, wherein there are two first direction ceiling's (30) and one second direction coiling (40) .
8. Method according to claim 6 or 7, wherein each first kind coiling (30) comprises two loops, and each second kind coiling (40) comprises four loops.
9. Method according to any of the preceding claims, wherein the method is used to detect a loose connection of the conductors (10) .
10. Method according to any of the preceding claims, wherein the conductors (10) are divided into groups of three, where for each group the tree conductors (10) are connected with a measuring wire (20) .
11. Method according to any of the preceding claims, the aggregated number of loops N1 of the first 30 equals the aggregated number of loops N2 of the second 40 direction coiling' s .
12. Wind turbine (1) comprising means to control if there is substantially equal current in a plural of Cn conductors (10) , the means including arrange a measuring wire (20) arranged with a first direction coiling (30) formed of N1 loops around a first of the conductors (10) and a second direction coiling (40) formed of N2 loops around Cn2 of a second of the conductors (10) at the opposite looping direction relative to the first direction coiling (30) , wherein number of loops N1 and N2 is selected such that thecurrent induced in the measuring wire (20) due to inductance by the currents in the conductors (10) theoretically adds to value below a threshold T, and detect it as an inequality among the conductors (10) if the added measurement exceeds the threshold T, and the number Cnl of the first conductors are different from the number Cn2 of the second conductors.
13. Wind turbine (1) according to claim 12, wherein it includes the means for operating according to the method of any of claims 2-11.