CN111812473B - Method for rapidly estimating electrical service life of stator bar of high-voltage motor - Google Patents
Method for rapidly estimating electrical service life of stator bar of high-voltage motor Download PDFInfo
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- CN111812473B CN111812473B CN202010722409.XA CN202010722409A CN111812473B CN 111812473 B CN111812473 B CN 111812473B CN 202010722409 A CN202010722409 A CN 202010722409A CN 111812473 B CN111812473 B CN 111812473B
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- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The invention discloses a method for quickly estimating the electrical service life of a stator bar of a high-voltage motor. Based on the electrical aging test of a group of stator bars and the transient breakdown test of a group of stator bars, the Weibull distribution state and the breakdown time of other electrical aging test and transient breakdown test stator bars can be quickly estimated by drawing on a Weibull distribution failure probability diagram according to the relationship of Weibull parameters under different tests. The method has the characteristics of simplicity, clear flow, quick analysis and wide applicability, can greatly reduce the service life prediction cost of the stator bar under the condition of quickly and accurately predicting the electrical service life of the stator bar, effectively improves the insulation design of the stator bar and improves the insulation performance of the stator bar.
Description
Technical Field
The invention relates to a method for quickly estimating the electrical life of a stator bar of a high-voltage motor.
Background
The stator bar is a core component of a high-voltage motor, bears the comprehensive action of various stresses such as electrical stress, thermal stress and the like in tests and operation, and the reliability and the service life of the stator bar play a decisive role in the stable operation of a machine set. The insulation life of the stator bar determines the life of a generator stator winding, the electrical insulation life and the distribution state of the stator bar are rapidly and accurately estimated, and the method plays a very important role in guiding the insulation design and optimization of the stator bar.
In the estimation of the insulation life of the stator bar, 2 groups of electrical aging test data and more are generally used, and the insulation life of the stator bar under other voltages is obtained by a method of negative power straight line extrapolation. The traditional method for extrapolating the insulation life has long test time and high test cost. Meanwhile, the method cannot obtain the distribution state of the insulation life of the stator bar, and cannot estimate the life of the instantaneous breakdown test, so that the method has certain limitation.
Disclosure of Invention
The invention aims to establish a rapid estimation method for the electrical service life of a stator bar of a high-voltage motor, which has the characteristics of simple method, clear flow, rapid analysis and wide applicability, can rapidly and accurately estimate the electrical aging service life of the stator bar under different test voltages and the electrical breakdown service life of the stator bar under different boosting speeds, effectively estimate the electrical insulation performance of the stator bar, greatly reduce the service life estimation test cost of the stator bar and guide the insulation design and optimization of the stator bar. The technical scheme of the invention is as follows:
a method for rapidly estimating the electrical life of a stator bar of a high-voltage motor comprises the following steps:
1) Making 20 high-voltage motor stator bars, dividing each group into two groups of 10, testing in transformer oil at 15-25 deg.C by using high-voltage testing transformer, and making the first group have constant voltage of 3U N Electrical aging test of (2), wherein U N The second group carries out an instantaneous breakdown test at a constant boosting speed of 1kV/s for the rated voltage of the stator bars until all the stator bars are broken down;
2) According to the test result, obtaining the breakdown time of the electrical aging test of the first group of 10 stator bars, and obtaining the breakdown time of the instantaneous breakdown test of the second group of 10 stator bars;
3) Corresponding breakdown time t of 10 breakdown points of the first group of electrical aging tests i And probability of failure P i Drawn on a Weibull failure probability chart, and fitted with aging data points into a straight line L 1 ，L 1 To a known voltage of 3U N A Weibull failure probability straight line of the lower electrical aging test corresponds the breakdown time t 'of 10 breakdown points of the second group of transient breakdown tests' i And probability of failure P' i Drawn on a Weibull failure probability chart, and a straight line L is fitted to breakdown data points 2 ，L 2 A Weibull failure probability straight line of an electrical breakdown test at a known boosting speed of 1 kV/s;
4) Drawing a characteristic life probability straight line L with failure probability P =63.2% c ，L c And L 1 Has a cross point of q 1 ，q 1 Corresponding time t c1 Is at a voltage of 3U N Characteristic life of the Power-off aging test, L c And L 2 Has a cross point of q 2 ，q 2 Corresponding time t c2 The characteristic life of the transient breakdown test at the boosting speed of 1 kV/s;
5) On the Weibull failure probability chart, a straight line is drawnL 1 And L 2 Extending along the direction of the negative axis, intersecting two straight lines at a point A, wherein the time corresponding to the point A is t a ；
6) For constant test voltage U 1 Electrical aging test of stator bar of (1), its Weibull distribution line L 3 And a straight line L 2 Time t corresponding to the intersection B of b Comprises the following steps:
wherein, U 1 Is the constant test voltage, U, of the electrical aging of the stator bar needing to estimate the characteristic life N Rated voltage of stator bar, t a Is a known Weibull failure probability straight line L of an electrical aging test 1 With known electric breakdown test Weibull failure probability straight line L 2 The time corresponding to the crossing point A is represented by an electrical aging straight line L passing through the crossing point B on a Weibull failure probability chart 1 Is parallel line L of 3 And extending to a region with failure probability P =1% -99%, L 3 Is a constant test voltage U 1 Weibull distribution line, L, of lower electrical aging test c And L 3 Of the intersection point q 3 Corresponding time tc 3 Is a constant test voltage U 1 Predicted characteristic life of lower electrical ageing test when constant test voltage U 1 When the operating voltage of the stator bar is equal, the obtained characteristic service life is the estimated operating service life of the stator bar;
7) For constant boost speed k 1 In a stator bar electrical breakdown test of Weibull distribution line and L 1 Time t corresponding to the intersection point C of c Comprises the following steps:
t c ＝k 1 t a
wherein k is 1 The step-up speed of the electrical breakdown test of the stator bar needing to estimate the characteristic life is determined by taking a transient breakdown straight line L at a passing point C on a Weibull failure probability chart 2 Is parallel to the line L 4 And extending to a region with failure probability P =1% -99%, L 4 To estimate a constant boost speed k 1 Weibull distribution of lower electric breakdown testLine, L c And L 4 Cross point q of 4 Corresponding time t c4 Is a constant step-up speed k 1 Predicted characteristic life of the next transient breakdown test.
Technical effects
The invention provides a method for quickly estimating the electrical life of a high-voltage motor stator bar, which is different from the traditional method for linearly extrapolating the insulation life by using negative power of the stator bar and has the following technical effects:
a) The total test time is short, and the test cost is greatly reduced. More than 2 groups of electrical aging tests are used in the traditional method, the breakdown time of the electrical aging test with lower test voltage is longer, and certain dispersity exists, so that the total test time reaches more than thousands of hours. By using the rapid evaluation method, the test voltage of the electrical aging test is higher, the breakdown time is shorter, the breakdown time of the instantaneous breakdown test is shorter, the total time is less than hundreds of hours, and compared with the traditional method, the test time is greatly shortened to about 10 percent of the original time;
b) The rapid evaluation method can not only predict the electrical aging insulation life of the stator bar under constant voltage, but also predict the instantaneous breakdown insulation life of the stator bar under constant boosting speed, and has wide universality, while the traditional method can only predict the electrical aging insulation life of the stator bar under constant voltage;
c) The rapid evaluation method can not only estimate the insulation life of the stator bar, but also estimate the Weibull distribution state of the stator bar, and more comprehensively master the insulation life information of the stator bar.
Drawings
FIG. 1 is a schematic diagram of a method for rapidly estimating the electrical life of a stator bar of a high-voltage motor
Detailed Description
A method for rapidly estimating the electrical life of a stator bar of a high-voltage motor comprises the following steps:
1) Manufacturing 20 high-voltage motor stator bars which are divided into two groups, wherein each group comprises 10 stator bars, testing the stator bars in transformer oil by using a high-voltage testing transformer at the temperature of between 15 and 25 ℃,the first group is carried out at a constant voltage of 3U N Electrical aging test of (2), wherein U N The second group carries out an instantaneous breakdown test at a constant boosting speed of 1kV/s for the rated voltage of the stator bars until all the stator bars are broken down;
2) According to the test result, obtaining the breakdown time of the electrical aging test of the first group of 10 stator bars, and obtaining the breakdown time of the transient breakdown test of the second group of 10 stator bars;
3) As shown in FIG. 1, the breakdown time t corresponding to 10 breakdown points of the first set of electrical aging tests i And probability of failure P i Drawn on a Weibull failure probability chart, and fitted with aging data points into a straight line L 1 ，L 1 To a known voltage of 3U N A Weibull failure probability straight line of the lower electrical aging test corresponds the breakdown time t 'of 10 breakdown points of the second group of transient breakdown tests' i And probability of failure P' i Drawn on a Weibull failure probability chart, and a straight line L is fitted to breakdown data points 2 ，L 2 Is a Weibull failure probability straight line of an electrical breakdown test at a known boosting speed of 1 kV/s;
4) Drawing a characteristic life probability straight line L with failure probability P =63.2% c ，L c And L 1 Has a cross point of q 1 ，q 1 Corresponding time t c1 Is a voltage of 3U N Characteristic life of the Power-off aging test, L c And L 2 Has a cross point of q 2 ，q 2 Corresponding time t c2 The characteristic life of the transient breakdown test at the boosting speed of 1 kV/s;
5) On the Weibull failure probability chart, a straight line L is drawn 1 And L 2 Extending along the direction of the negative axis, intersecting two straight lines at a point A, and the time corresponding to the point A is t a ；
6) For constant test voltage U 1 Electrical aging test of stator bar of (1), its Weibull distribution line L 3 And a straight line L 2 Time t corresponding to intersection point B of (1) b Comprises the following steps:
wherein, U 1 Is the constant test voltage, U, of the electrical aging of the stator bar needing to estimate the characteristic life N Rated voltage of stator bar, t a Is a known Weibull failure probability straight line L of an electrical aging test 1 With known electric breakdown test Weibull failure probability straight line L 2 The time corresponding to the crossing point A is represented by an electrical aging straight line L passing through the crossing point B on a Weibull failure probability chart 1 Is parallel line L of 3 And extending to a region with failure probability P =1% -99%, L 3 Is a constant test voltage U 1 Weibull distribution line, L, of lower electrical aging test c And L 3 Of the intersection point q 3 Corresponding time tc 3 Is a constant test voltage U 1 Predicted characteristic life of lower electrical ageing test when constant test voltage U 1 When the operating voltage of the stator bar is equal, the obtained characteristic service life is the estimated operating service life of the stator bar;
7) For constant boost speed k 1 Electric breakdown test of stator bar of which the Weibull distribution is linear and L 1 Time t corresponding to intersection point C of (1) c Comprises the following steps:
t c ＝k 1 t a
wherein k is 1 The step-up speed of the electrical breakdown test of the stator bar needing to estimate the characteristic life is determined by taking an instantaneous breakdown straight line L at a crossing point C on a Weibull failure probability chart 2 Is parallel to the line L 4 And extending to a region with failure probability P =1% -99%, L 4 To estimate a constant boost speed k 1 Weibull distribution line, L, of lower electrical breakdown test c And L 4 Cross point q of 4 Corresponding time t c4 Is a constant step-up speed k 1 Predicted characteristic life of the next transient breakdown test.
Claims (1)
1. A method for quickly estimating the electrical service life of a stator bar of a high-voltage motor is characterized by comprising the following steps: the method comprises the following steps:
1) Manufacturing 20 high-voltage motor stator bars which are divided into two groups, wherein each group comprises 10 stator bars and the temperature is 15-25 DEG CNext, the test was carried out in transformer oil using a high-voltage test transformer, the first group being carried out at a constant voltage of 3U N Electrical aging test of (2), wherein U N The second group carries out an instantaneous breakdown test at a constant boosting speed of 1kV/s for the rated voltage of the stator bars until all the stator bars are broken down;
2) According to the test result, obtaining the breakdown time of the electrical aging test of the first group of 10 stator bars, and obtaining the breakdown time of the instantaneous breakdown test of the second group of 10 stator bars;
3) Corresponding breakdown time t of 10 breakdown points of the first group of electrical aging tests i And probability of failure P i Drawn on a Weibull failure probability chart, and fitted with aged data points to form a straight line L 1 ，L 1 For a known voltage of 3U N A Weibull failure probability straight line of the lower electrical aging test corresponds the breakdown time t 'of 10 breakdown points of the second group of transient breakdown tests' i And failure probability P' i Drawn on a Weibull failure probability chart, and a straight line L is fitted to breakdown data points 2 ，L 2 A Weibull failure probability straight line of an electrical breakdown test at a known boosting speed of 1 kV/s;
4) Drawing a characteristic life probability straight line L with failure probability P =63.2% c ，L c And L 1 Is q at the intersection point of 1 ，q 1 Corresponding time t c1 Is at a voltage of 3U N Characteristic life of the Power-off aging test, L c And L 2 Has a cross point of q 2 ，q 2 Corresponding time t c2 The characteristic life of the transient breakdown test at the boosting speed of 1 kV/s;
5) On the Weibull failure probability chart, a straight line L is drawn 1 And L 2 Extending along the direction of the negative axis, intersecting two straight lines at a point A, and the time corresponding to the point A is t a ；
6) For constant test voltage U 1 Electrical aging test of stator bar of which Weibull distribution line L is 3 And a straight line L 2 Time t corresponding to intersection point B of (1) b Comprises the following steps:
wherein, U 1 Is the constant test voltage, U, of the electrical aging of the stator bar needing to estimate the characteristic life N Rated voltage of stator bar, t a Is a known Weibull failure probability straight line L of an electrical aging test 1 With known electric breakdown test Weibull failure probability straight line L 2 The time corresponding to the intersection point A is on the Weibull failure probability chart, and the electrical aging straight line L is made by the intersection point B 1 Is parallel to the line L 3 And extending to the area, L, with failure probability P =1% -99% 3 Is a constant test voltage U 1 Weibull distribution line, L, of lower electrical aging test c And L 3 Cross point q of 3 Corresponding time tc 3 Is a constant test voltage U 1 Estimated characteristic life of the lower electrical aging test when constant test voltage U 1 When the operating voltage of the stator bar is equal, the obtained characteristic service life is the estimated operating service life of the stator bar;
7) For constant boost speed k 1 Electric breakdown test of stator bar of which the Weibull distribution is linear and L 1 Time t corresponding to intersection point C of (1) c Comprises the following steps:
t c ＝k 1 t a
wherein k is 1 The step-up speed of the electrical breakdown test of the stator bar needing to estimate the characteristic life is determined by taking an instantaneous breakdown straight line L at a crossing point C on a Weibull failure probability chart 2 Is parallel to the line L 4 And extending to a region with failure probability P =1% -99%, L 4 To estimate a constant boost speed k 1 Weibull distribution line, L, of lower electrical breakdown test c And L 4 Cross point q of 4 Corresponding time t c4 Is a constant step-up speed k 1 Predicted characteristic life of the next transient breakdown test.
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| JP4675837B2 (en) * | 2006-06-21 | 2011-04-27 | 中部電力株式会社 | Evaluation method of remaining life of turbine generator stator coil |
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