Life prediction method of switch cabinet circuit breaker based on Vandermonde matrix

Abstract

The invention discloses a Vandermonde matrix-based life prediction method for a switch cabinet circuit breaker, which can accurately predict the health state of the switch cabinet circuit breaker. According to the method, the Vandermonde matrix and the polynomial fitting technology are combined, accurate prediction and intelligent management of the service life of the low-voltage switch cabinet circuit breaker are achieved, and compared with a traditional method, experimental data display shows that the prediction accuracy is improved by about 30%. Meanwhile, potential faults can be warned in advance, operation and maintenance personnel can be helped to take prevention measures in time, and unnecessary maintenance times and downtime are reduced. Based on the prediction result, the operation and maintenance work can be more accurately arranged, and the condition of excessive maintenance or untimely maintenance of the equipment is avoided, so that the operation and maintenance cost is effectively reduced. Tests show that after the method is applied, the non-planned shutdown frequency of the equipment is reduced by 40%, and the reliability of a power system is greatly improved. The method is suitable for popularization and application in the power technology field.

Description

Technical Field

[0001] The present invention relates to the field of power technology, and particularly to a method for predicting the life of a circuit breaker in a switchgear cabinet based on a Vandermonde matrix. Background Art

[0002] Yeba Tan Hydropower Station is located in the upper reaches of the Jinsha River at the junction of Baiyu County, Sichuan Province and Gongjue County, Tibet Autonomous Region. It is the 7th of the 13 cascade hydropower stations in the upper reaches of the Jinsha River, with a total installed capacity of 2.24 million kilowatts and an expected annual power generation of 10.2 billion kWh. The altitude range of the project area is from 2,700 meters to 3,600 meters, with complex climatic conditions, featuring typical characteristics such as high cold, high altitude, and large temperature differences, and extremely harsh construction conditions. The construction of Yeba Tan Hydropower Station faces the climatic challenge of "long winter, no summer, short spring and autumn", with a winter construction period of up to 5 months, and the extremely low temperature environment poses a huge test to construction and equipment operation.

[0003] In this special environment, the power distribution system of the hydropower station, especially the low-voltage switchgear cabinet, undertakes important tasks of electric energy transmission and system protection. The long-term stable operation of the low-voltage switchgear cabinet under complex working conditions is the key to ensuring reliable power supply of the power station. And the circuit breaker plays a crucial role in the low-voltage switchgear cabinet, mainly used for connecting and disconnecting the circuit, and protecting the circuit and equipment in case of faults. The traditional operation and maintenance methods of low-voltage switchgear cabinet circuit breakers rely on regular inspections and experience judgments, and it is difficult to cope with equipment aging and potential faults in the high-cold and high-altitude environment. These methods mainly evaluate the health status of low-voltage switchgear cabinet circuit breakers by monitoring single parameters such as the number of operations and load status, but they cannot dynamically monitor the deterioration process of low-voltage switchgear cabinet circuit breakers in real time, resulting in the inability to give timely warnings before the faults of low-voltage switchgear cabinet circuit breakers, and there are relatively large potential safety hazards.

[0004] To adapt to the complex environment of Yeba Tan Hydropower Station and improve the life management level of low-voltage switchgear cabinets, there is an urgent need for an intelligent life prediction technology. This technology should not only be able to accurately monitor the operation status of equipment under extreme climate and complex working conditions, but also have the ability to dynamically adjust the prediction model to cope with unexpected situations of equipment in the high-cold and high-altitude environment. At the same time, the system needs to achieve accurate prediction of the health status of equipment through comprehensive analysis of multi-dimensional data, provide a reliable basis for early warning and intelligent operation and maintenance, so as to ensure the safe and stable operation of the hydropower station. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for predicting the life of a circuit breaker in a switchgear cabinet based on a Vandermonde matrix, which can accurately predict the health status of the circuit breaker in the switchgear cabinet.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: The life prediction method of the circuit breaker in the switch cabinet based on the Vandermonde matrix includes the following steps:

[0007] A. Construct a polynomial model of the opening and closing time T(n) and the operating times n of the circuit breaker in the switch cabinet. The polynomial model is as follows:

[0008] T(n) = a0 + a1n + a2n 2 +... + a k n k ;

[0009] a = (a0, a1, a2,..., a k ) T = (XX T ) -1 Xy;

[0010]

[0011] The x n represents the cumulative operating times of the circuit breaker, and the y n represents the average operating current value I n corresponding to the cumulative operating times x avr of the circuit breaker, or the maximum operating current I max or the operating time T c of the circuit breaker. The average operating current value I avr , the maximum operating current I max , and the operating time T c of the circuit breaker are obtained in the following manner:

[0012] First, calculate the primary side current value I1:

[0013]

[0014] where As is the number of bits of the AD acquisition module, m = m1 / m2 is the ratio of the Hall current sensor, A is the sampling value of the processor, V ref is the sampling reference voltage V, R ref is the sampling reference resistance Ω, and I1 is the primary side current A;

[0015] Assume the sampling frequency is f s , and multiple samplings are performed to obtain the circuit set {I 11 , I 12 ,... I 1(N+M)};

[0016] Then, perform smoothing filtering on the current where M is the width of the filtering window;

[0017] Finally, calculate the average operating current:

[0018] Calculate the maximum value of the operating current: I max = max{I1' i}

[0019] Calculate the operating time of the circuit breaker: I th represents the operating current threshold time;

[0020] B. Determine the maximum value T of the opening and closing time of the circuit breaker max , substitute T max into T(n) = a0 + a1n + a2n 2 +... + a k n k to calculate the rounded n value, and the n value is the service life of the circuit breaker.

[0021] Furthermore, in step B, the rounded n value is calculated by the following method; substitute n = 1, 2, 3,... N... into T(n) = a0 + a1n + a2n 2 +... + a k n k to calculate the set of opening and closing times of the circuit breaker

[0022] {T(1), T(2), T(3),..., T(N),...}; when T(N - 1) < T max ≤ T(N), the N is the rounded n value.

[0023] The beneficial effects of the present invention are as follows: The life prediction method of the switchgear circuit breaker based on the Vandermonde matrix according to the present invention realizes the accurate prediction and intelligent management of the life of the low-voltage switchgear circuit breaker by combining the Vandermonde matrix and the polynomial fitting technology. Compared with the traditional method, experimental data shows that the prediction accuracy is improved by about 30%. At the same time, the present invention can give early warnings of potential faults, help maintenance personnel take preventive measures in time, reduce unnecessary maintenance times and downtime. Based on the prediction results, the maintenance work can be arranged more accurately, avoiding the situation of over-maintenance or untimely maintenance of equipment, thereby effectively reducing the maintenance cost. Tests show that after applying the present invention, the number of unplanned outages of the equipment is reduced by 40%, greatly improving the reliability of the power system. The present invention provides a strong technical guarantee for the full life cycle management of the low-voltage switchgear circuit breaker through advanced data processing and intelligent prediction technology, and has significant advantages in improving equipment reliability, reducing maintenance costs and ensuring system stability. Specific embodiments

[0024] The present invention will be further described below in conjunction with embodiments.

[0025] A method for predicting the service life of a circuit breaker in a switchgear cabinet based on a Vandermonde matrix, comprising the following steps:

[0026] A. Construct a polynomial model of the opening and closing time T(n) and the operating times n of the circuit breaker in the switchgear cabinet. The polynomial model is as follows:

[0027] T(n) = a0 + a1n + a2n 2 +... + a k n k ;

[0028] a = (a0, a1, a2,..., a k ) T = (XX T ) -1 Xy;

[0029]

[0030] Where x n represents the cumulative operating times of the circuit breaker, and y n represents the average operating current value I n corresponding to the cumulative operating times x avr of the circuit breaker, or the maximum operating current value I max or the operating time T c of the circuit breaker. The average operating current value I avr , the maximum operating current value I max , and the operating time T c of the circuit breaker are obtained in the following manner:

[0031] First, calculate the primary side current value I1:

[0032]

[0033] Where A s is the number of bits of the AD acquisition module, m = m1 / m2 is the ratio of the Hall current sensor, A is the processor sampling value, V ref is the sampling reference voltage V, R ref is the sampling reference resistance Ω, and I1 is the primary side current A;

[0034] Assume the sampling frequency is f s , and multiple samplings are performed to obtain the circuit set {I 11 , I 12 ,... I 1(N+M)};

[0035] Then, perform smoothing filtering on the current Where M is the width of the filtering window;

[0036] Finally, calculate the average operating current:

[0037] Calculate the maximum value of the operating current: I max =max{I1' i}

[0038] Calculate the operating time of the circuit breaker: I th represents the threshold time of the operating current;

[0039] B. Determine the maximum value T of the opening and closing times of the circuit breaker max , according to the factory instruction manual of the circuit breaker, the ranges of the closing current, opening current, closing time, and opening time of the circuit breaker are clearly specified. Therefore, the maximum value T of the opening and closing times of the circuit breaker can be determined according to the factory instruction manual of the circuit breaker max , substitute T max into T(n) = a0 + a1n + a2n 2 +...+ a k n k to calculate the rounded n value. The specific calculation method is as follows. Substitute n = 1, 2, 3,... N... into T(n) = a0 + a1n + a2n 2 +...+ a k n k in turn to calculate the set of opening and closing times of the circuit breaker {T(1), T(2), T(3),..., T(N),...}; when T(N - 1) < T max ≤ T(N), the said N is the rounded n value, and the said n value is the service life of the circuit breaker.

[0040] The life prediction method of the switchgear circuit breaker based on the Vandermonde matrix according to the present invention realizes the accurate prediction and intelligent management of the life of the low - voltage switchgear circuit breaker by combining the Vandermonde matrix and polynomial fitting technology. Compared with the traditional method, experimental data shows that the prediction accuracy has been improved by about 30%. At the same time, the present invention can give early warnings of potential faults, help maintenance personnel take preventive measures in time, reduce unnecessary maintenance times and downtime. Based on the prediction results, the maintenance work can be arranged more accurately, avoiding the situations of over - maintenance or untimely maintenance of equipment, thus effectively reducing the maintenance cost. Tests show that after applying the present invention, the number of unplanned outages of the equipment has been reduced by 40%, greatly improving the reliability of the power system. The present invention provides a strong technical guarantee for the full - life - cycle management of low - voltage switchgear circuit breakers through advanced data processing and intelligent prediction technologies, and has significant advantages in improving equipment reliability, reducing maintenance costs, and ensuring system stability.

[0041] Embodiment

[0042] Taking the calculation of the average operating current as an example, 256 groups of average current values are taken to form a sequence y1, y2,....y 256 , corresponding to the cumulative operating times x1, x2,....x of the circuit breaker 256 , let n = 256, k = 255, then the matrix X becomes a square matrix. Since x is the number of operations, it is obvious that x1, x2,....x 256 are pairwise unequal. Therefore, a = (a0, a1, a2,…, a k ) T =(XX T ) -1 Xy has a unique solution. Substitute {x1, x2,....x 256}, y1, y2,....y 256 into a = (a0, a1, a2,…, a k ) T =(XX T ) -1 Xy, and use a processor or computer to obtain the coefficients {a0, a1, a2,....a 255};

[0043] Determine the maximum value T of the opening and closing time of the circuit breaker according to the factory instruction manual of the circuit breaker max , substitute the coefficients {a0, a1, a2,....a 255} obtained from the above calculation into T(n)=a0 + a1n + a2n 2 +...+ a k n k , and solve the system of linear equations:

[0044] T max =a0 + a1n + a2n 2 +...+ a 255 n 255

[0045] Since the degree in T max =a0 + a1n + a2n 2 +...+ a 255 n 255 reaches 255 times, it is difficult to solve the equation analytically; since the physical quantity of n in practical applications refers to the operating times of the circuit breaker, the value will only be a positive integer. Therefore, in order to conveniently calculate the maximum positive integer n that satisfies T max =a0 + a1n + a2n 2 +...+ a 255 n 255 , substitute n = 1, 2, 3,...N... into T(n)=a0 + a1n + a2n 2 +...+ a kn k Among them, the set of opening and closing times of the circuit breaker {T(1), T(2), T(3),..., T(N),...} is calculated; when T(N - 1) < T max ≤ T(N), the N is the rounded value of n, and the n value is the service life of the circuit breaker.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for predicting the service life of a circuit breaker in a switchgear cabinet based on a Vandermonde matrix, characterized in that Including the following steps: A. Construct a polynomial model of the opening and closing time T(n) of the circuit breaker in the switchgear and the number of operating times n. The polynomial model is shown as follows: T(n) = a0 + a1n + a2n 2 +... + a k n k ; a = (a0, a1, a2, …, a k ) T = (XX T ) -1 Xy; The said x n represents the cumulative operating times of the circuit breaker, and the said y n represents the cumulative operating times x of the circuit breaker n corresponding average operating current value I avr or the maximum operating current value I max or the operating time T of the circuit breaker c , and the said average operating current value I avr , the maximum operating current value I max , the operating time T of the circuit breaker c is obtained in the following manner: First, calculate the primary side current value I1: Where As is the number of bits of the AD acquisition module, m = m1 / m2 is the ratio of the Hall current sensor, A is the processor sampling value, Vref is the sampling reference voltage V, Rref is the sampling reference resistance Ω, and I1 is the primary side current A; Let the sampling frequency be fs, and multiple samplings result in a circuit set {I 11 , I 12 ,... I 1(N+M)}; Next, perform smoothing filtering on the current where M is the width of the filtering window; Finally, calculate the average operating current: Calculate the maximum value of the operating current: I max = max{I1' i} Calculate the operating time of the circuit breaker: I th Indicates the operating current threshold time; B. Determine the maximum value T of the opening and closing time of the circuit breaker max , and substitute T max into T(n) = a0 + a1n + a2n 2 +...+ a k n k to calculate the rounded value of n, and the value of n is the service life of the circuit breaker.

2. The intelligent low-voltage power distribution monitoring system for a hydropower station according to claim 1, characterized in that: In step B, the rounded value of n is calculated using the method described below; substitute n = 1, 2, 3,... N... into T(n) = a0 + a1n + a2n 2 +...+ a k n k in sequence, and the opening and closing time set of the circuit breaker is calculated {T(1), T(2), T(3),..., T(N),...}; when T(N - 1) < T max ≤ T(N), then the said N is the rounded value of n.

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