Method and system for monitoring the quality of fluids

Abstract

A method and system for monitoring the quality of fluids, wherein comprising the different features of a fluid with at least two different methods are measured and a measure for the quality of the fluid is derived and/or a process of the fluid deterioration is identified by comparing the results of the measurements of the at least two different methods, where the methods includes at least one optical absorption measurement and at least one electron paramagnetic resonance measurement.

Claims

1. A method for monitoring quality of fluids, comprising: measuring different features of a fluid with at least two different methods comprising at least a first measurement method and at least a second measurement method which are implemented simultaneously; and comparing results of the measurements of the at least two different methods comprising at least the first measurement method and at least the second measurement method which are implemented simultaneously to at least one of (i) derive a measure for a quality of the fluid and (ii) identify a process of the fluid deterioration; wherein the first and the second measurement methods each comprise at least one optical absorption measurement and at least one electron paramagnetic resonance measurement.

2. The method according to claim 1, wherein the method is implemented to identify aging of the fluid in connection with plastic or other incompatible materials.

3. The method according to claim 2, wherein the aging comprises chemical aging.

4. The method according to claim 3, wherein the chemical aging comprises at least one of a change of acidity, water content and free radicals concentration.

5. The method according to claim 2, wherein the aging comprises at least one of thermal aging and aging over time.

6. The method according to claim 1, wherein the fluid is at least one of (i) a dielectric liquid and (ii) an oil.

7. The method according to claim 2, wherein the fluid is at least one of (i) a dielectric liquid and (ii) an oil.

8. The method according to claim 6, wherein the fluid is one of (i) a highly-refined mineral oil or synthetic ester, and (ii) a mixture comprising at least one of a dielectric liquid and an oil.

9. The method according to claim 7, wherein the fluid is one of (i) a highly-refined mineral oil or synthetic ester, and (ii) a mixture comprising at least one of a dielectric liquid and an oil.

10. The method according to claim 1, wherein the measurements are performed at least one of (i) remotely, (ii) under high pressure and (iii) in a closed system.

11. The method according to claim 1, wherein the fluid is enclosed by a power grid unit.

12. The method according to claim 11, wherein the power grid unit is at least one of a transformer, a switchgear and a variable speed drive.

13. The method according to claim 1, further comprising: at least one of (i) determining a fluid deterioration process and (ii) discrimination between fluid deterioration processes.

14. The method according to claim 1, wherein at least one of (i) a electron paramagnetic resonance measurement signal comprising at least one of an integral value and spectrum, (ii) an absorption in at least one of a visible spectral range and another range comprising a fixed range or several ranges of wavelength as at least one of an integral value and spectrum, measured in transmission, as turbidity and change in color, is measured in combination.

15. The method as claimed in claim 14, wherein the measurements are performed in parallel at the same time.

16. The method according to claim 1, wherein a measure for quality is derived by comparing the measured values of the at least two different methods comprising at least the first measurement method and at least the second measurement method with standard values; and wherein a low quality is identified when at least one of the measured values is higher or lower than the standard value.

17. The method according to claim 16, wherein an acceptable quality for use is identified with both values lower than a standard value, and a necessary exchange of fluid is identified with at least one or both of the measured values being higher than the standard value.

18. The method according to claim 17, wherein the standard value comprises a turbidity in a visible spectral range and an integral of an electron paramagnetic resonance measurement signal.

19. The method according to claim 1, wherein the measuring occurs in high pressure conditions.

20. The method according to claim 19, wherein the pressure is higher than 200 bar.

21. A system comprising: a power grid unit having at least one device for an optical absorption measurement; and at least one device for an electron paramagnetic resonance measurement (EPR), the system being monitored by: measuring different features of a fluid with at least two different methods comprising at least a first measurement method and at least a second measurement method which are implemented simultaneously; and comparing results of the measurements of the at least two different methods comprising at least the first measurement method and at least the second measurement method which are implemented simultaneously to at least one of (i) derive a measure for a quality of the fluid and (ii) identify a process of the fluid deterioration; wherein the first and the second measurement methods each comprise at least one optical absorption measurement and at least one electron paramagnetic resonance measurement.

22. The system according to claim 21, further comprising: at least one of a transformer, a switchgear and variable speed drive.

23. The system according to claim 21, further comprising: a fluid in a closed container; wherein the at least one device for the optical absorption measurement and the at least one device for the electron paramagnetic resonance measurement are within or at the container.

24. The system according to claim 22, further comprising: a fluid in a closed container; wherein the at least one device for the optical absorption measurement and the at least one device for the electron paramagnetic resonance measurement are within or at the container.

25. The system according to claim 21, further comprising: a device to at least one of (i) remotely control the measured data and (ii) analyze the measured data; wherein the device compares a value obtained by the at least one device for the optical absorption measurement and the value obtained by the at least one device for the electron paramagnetic resonance measurement with standard values and derives a quality of the fluid from a combination of compared values.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is further described hereinafter with reference to illustrated embodiments shown in the accompanying drawings, in which:

(2) FIG. 1 illustrates a graphical plot of data from an optical absorption measurement;

(3) FIG. 2 illustrates a bar chart of data of an electron paramagnetic resonance measurement EPR;

(4) FIG. 3 illustrates the method in accordance with the present invention, deriving a measure for the quality of a fluid and aging mechanism by comparing the results of the measurements of FIGS. 1 and 2; and

(5) FIG. 4 is flowchart of the method in accordance with the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

(6) In FIG. 1 an optical absorption measurement within visible spectral range VIS for a fluid Midel 7131 is shown. Midel 7131 is a liquid for oil-filled transformers and consists of a synthetical ester. Midel 7131 is fire and environmentally safe. In non deteriorated, non aged stage, it is transparent, with a bit of yellow color.

(7) In transmission spectra of FIG. 1, the transmission in percent %, depending on wavelength in nm in the spectral UV-VIS range is shown. Sample 1 and 6 are non aged, not deteriorated. Midel 7131. Sample 1 is a more color less sample and sample 6 is of a bit more yellow color manually viewed. Both samples 1 and 6 show a high transmission in % in the UV-VIS spectra.

(8) Samples 3 and 4 are liquid Midel 7131 aged thermally, in contact with Nomex at elevated temperatures. The aging has been performed for 2000 hours (sample 3) and 4000 hrs (sample 4), both at 150 C. Nomex is a flame-resistant meta-armid polymer material. Nomex can be produced in the form of paper sheets, particularly used for electrical insulation. As seen in FIG. 1 the transmission T.sub.r of samples 3 and 4 is lower than that of imaged samples 1 and 6 in the entire UV-VIS range. The visible color of sample 3 is strong yellow and the visible color of sample 4 is strong brown/red.

(9) Sample 2 is liquid Midel 7131 aged with incompatible plastic. The aging has been performed for 3 months at 105 C. As seen in FIG. 1, the transmission T.sub.r of sample 2 is lower than the transmission T.sub.r of samples 1, 6, 3 and 4 nearly in the entire spectral UV-VIS range. Only sample 4 shows a slightly smaller or substantially the same transmission in a range of wavelength below 420 nm. The color of sample 2 is cloudy/milky yellow.

(10) Sample 5 is liquid Midel 7131 aged by a fuse breakdown. As seen in FIG. 1 the transmission T.sub.r of sample 2 is lower than the transmission of the other samples 1 to 4 and 6 in the entire spectral UV-VIS range. The visible color of sample 5 is dark black.

(11) Alternative to transmission T.sub.r curves in the UV-VIS range, the integral value of the area below the curve can be used as a result of the optical absorption measurement for evaluation of the quality of the fluid, particularly liquid. The information and result, is the same as described before for the transmission T.sub.r, dependent on wavelength A curves in the UV-VIS range.

(12) The light absorption within visible spectral range UV-VIS, as shown in FIG. 1, provides information on dielectric fluid turbidity and color. With this information, the optical absorption and/or turbidity can be measured either in the VIS or NIR range or in both ranges and/or in another wavelength range. In the example of FIG. 1 only the data on VIS range turbidity are shown for the sake of simplicity.

(13) In FIG. 2, Electron Paramagnetic Resonance (EPR) measurements on the same samples 1 to 6 of FIG. 1 are shown. The EPR signal S.sub.EPR is given in arbitrary units, depending on the sample number No. As can be seen in FIG. 2, the sample 5, liquid Midel 7131 aged by a fuse breakdown, shows very high vH EPR signal intensity I. It is the highest EPR signal intensity I of all measured samples 1 to 6.

(14) Samples 3 and 4, liquid Midel 7131 aged thermally in contact with Nomex at elevated temperatures, show a high H EPR signal S.sub.EPR. The EPR signal S.sub.EPR intensity I is lower than the signal intensity I of sample 5, but higher than the signal intensity I of samples 1, 2 and 6.

(15) Samples 1 and 6, unaged liquid Midel 7131, show low L EPR signal S.sub.EPR intensity I.

(16) Also sample 2, liquid Midel 7131 aged with incompatible plastic, shows low L EPR signal S.sub.EPR intensity I. It is even slightly lower than the intensity I of samples 1 and 6. Samples 1, 2 and 6 show all three low L intensity I in EPR signal S.sub.EPR measurements. It is not possible to distinguish aging from no aging alone on EPR measurements.

(17) In FIG. 3 a schema summarizing and comparing the measurements of transmission spectra of FIG. 1 in the spectral UV-VIS range and Electron Paramagnetic Resonance EPR measurements of FIG. 2 is shown. The results in form of qualitative information about turbidity T.sub.u in VIS range of FIG. 1, compared to results in form of qualitative information about the integral EPR signal S.sub.EPR of FIG. 2 are given.

(18) As evident from FIG. 3, fluid without deterioration can be distinctly identified and distinguished from aged fluid by comparing measured results of optical UV-VIS in combination with EPR measurements. A measure for the quality of the fluid is given in the form of the information aged or not aged by comparing the results of the measurements of the two different, methods optical UV-VIS and EPR measurement. With values for turbidity T.sub.u in VIS range low L and EPR signal S.sub.EPR low L the quality of fluid is good, and there is no requirement to change and/or exchange the fluid to guarantee a proper functional operation of equipment using the turbidity T.sub.u. With values for turbidity T.sub.u in VIS range low L and EPR signal S.sub.EPR high H, or values for turbidity T.sub.u in VIS range high H and EPR signal S.sub.EPR low L, or both values high K or very high vH, the quality of fluid is not good and must be further checked, changed and/or exchanged to guarantee a proper functional operation of equipment using the fluid. Further, the aging mechanism, see FIG. 3 second column, can be determined and distinguished.

(19) Only in combination is reliable information provided by the two methods about the quality of the liquid, particularly with respect to aging/deterioration, and the aging mechanism. With one method, it is not possible to reliably evaluate the quality and the need for action with respect to aging/deterioration of the liquid and its changing and/or exchange. The aging mechanism determined also provides information on the processes that may lead to its failure within equipment like transformers.

(20) Both methods, optical and EPR measurements can be performed remotely. This enables measurements and a quality evaluation in harsh environments, and/or a simultaneous monitoring of properties of a fluid particularly continuously, and/or online, such as with a computer. The disclosed embodiments offer an interpretation technique providing fluid deterioration scenario and reason identification.

(21) In the special case of FIG. 3, the measure for the quality of the fluid by comparing the results of the measurements of the two different methods, the optical and the Electron Paramagnetic Resonance SER measurements, is (i) low L VIS and low L EPR signals combination indicates no deterioration of the fluid, (ii) high H VIS and low L EPR signals combination indicates deterioration of the fluid by incompatible plastic, (iii) low L VIS and high H EPR signals combination indicates deterioration of the fluid with Nomex at high temperatures, and (iv) high R VIS and high H EPR signals combination indicates deterioration of the fluid by a fuse breakdown.

(22) For other applications and fluids, the specific measure and the scheme can be different. However, a clear determination of the quality of liquid is possible with a combination of the at least two methods also in other applications and for other liquids. The methodology illustrated in FIG. 3 is merely an example for the method for monitoring the quality of fluids in accordance with the present invention. The methodology of FIG. 3 can be used as described before, in combination with different features described before and in combination with conventional methods and features. The optical absorption (transparency) measurements can occur within a specific bandwidth or bandwidths of UV-VIS spectra. Either the integral optical signal or optical spectra can be used or both. For EPR signal acquisition, the integral signal and/or spectra can also be used. The data analysis and discrimination between several predetermined aging mechanisms can be performed manually or automatically, particularly after transmitting data from a remote measurement. NIR-MIR data can be used both on turbidity and on specific impurities present in the fluid, such as oil.

(23) Even when the methodology of deterioration scenario determination for different fluids is different in detail, it is possible to monitor and interpret optical and EPR signals at the same time for all fluids. This combination of optical and EPR monitoring provides a good basis for the fluid ageing scenario interpretation. This offers a safe and reliable tool for quality monitoring of, for example, isolating liquids for remote equipment, such as oil in transformers. The mutual optical and EPR data interpretation allows conclusions on the specific processes taking place in a fluid.

(24) Advantages of the present invention are, inter alia, the possibility to remotely monitor fluids properties without intervention to equipment working regime due to installed optical and EPR measurement sensors/systems, and more precisely to identify events such as equipment break down, compared with methods merely using optical or BEE signals alone, by analysing the reasons of the fluid deterioration. Equipment ageing can be calculated with the help of monitoring data, so as to avoid failures and expensive repairs of equipment. Equipment faults can be detected in their infancy, enabling fast remedial response. There is an easy adaptation of the proposed methodology for a variety of constructions and equipments. The technology can be implemented in high pressure conditions, for example in subsea equipment.

(25) FIG. 4 is a flowchart of a method for monitoring quality of fluids. The method comprises measuring different features of a fluid with at least two different methods, as indicated in step 410.

(26) Next, the results of the measurements of at least two different methods are compared to at least one of (i) derive a measure for a quality of the fluid and (ii) identify a process of the fluid deterioration, as indicated in step 420. In accordance with the method of the invention, at least two methods comprise at least one optical absorption measurement and at least one electron paramagnetic resonance measurement (EPR).

(27) While there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that Various omissions and substitutions and changes in the form and details of the methods described and the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.