KR102122580B1 - Apparatus and method for calculating service life of capacitor - Google Patents

Abstract

Provided is a capacitor life calculation method, which comprises the steps of: collecting temperature-life information of a capacitor, converting the temperature-life information to an Arrhenius equation factor, and calculating activation energy of the capacitor through regression analysis; acquiring the actual ambient temperature at a power plant site, acquiring the internal temperature and self-heating temperature of a capacitor device, and making a database; calculating a deterioration weighted average temperature, and calculating an operation temperature by replacing the calculated deterioration weighted average temperature with an actual ambient temperature; and calculating the life of the capacitor using the Arrhenius equation with the activation energy and the operating temperature as parameters.

Description

Capacitor life calculation method and device {APPARATUS AND METHOD FOR CALCULATING SERVICE LIFE OF CAPACITOR}

The present invention relates to a capacitor life estimation technique, and more particularly, to a method and apparatus for calculating a capacitor life using an equivalent temperature.

Capacitors are largely divided into dielectric capacitors and electrolytic capacitors depending on the material filling the inside. A dielectric capacitor is a structure in which a dielectric is disposed between two electrodes. The electrolytic capacitor has a structure in which a thin oxide film is formed on the anode surface, and an electrolyte is disposed between the oxide film and the cathode, and has a larger capacitance than the dielectric capacitor.

Capacitors function to store or discharge electric charges, to block direct current and to pass alternating current, and to rectify circuits of power supplies, delay circuits using charge and discharge times, and to extract or remove specific frequency components Used for filter circuits.

In industrial sites such as power plants, the life of the capacitor is calculated, and the capacitor is replaced according to the calculated life. In the process of acquiring various parameters necessary for estimating the life of the capacitor, a temperature profile is assumed according to verification requirements under normal and abnormal operation. However, the ambient temperature higher than the actual temperature can be selected as a parameter, and in this case, the heat aging conditions are somewhat excessively applied.

In the case of an electrolytic capacitor, if the temperature rises by 10°C, the life is reduced by half. When the temperature profile of the capacitor is applied to the overall high conservative overall, the replacement cycle of the capacitor is shortened, and inefficient maintenance can be performed, such as replacement with a new one, although there is no problem in performance.

The present invention is to provide a method and apparatus for estimating the life of a capacitor by applying a temperature profile of the capacitor based on the actual ambient temperature to prolong the replacement cycle of the capacitor and lower the purchasing cost of the capacitor through rational engineering and maintenance efficiency. .

Capacitor life estimation method according to an embodiment of the present invention, (i) collecting the temperature-life information of the capacitor, converting the collected temperature-life information to the Arrhenius equation factor, activation of the capacitor through regression analysis An activation energy calculation step for calculating energy, and (ii) an operating temperature calculation database unit for acquiring the actual ambient temperature at the site from the power plant operation information system and obtaining and storing the internal temperature and self-heating temperature of the capacitor device from the temperature measurement equipment. Operation temperature to calculate the deterioration-weighted average temperature based on the construction phase and (ⅲ) data of the operation temperature calculation database and capacitor properties, and calculate the operation temperature by replacing the calculated deterioration-weighted average temperature with the actual ambient temperature. It includes a calculation step, and (iv) a life calculation step of estimating the life of the capacitor using the Arrhenius equation with the activation energy and the operating temperature as parameters.

In the activation energy calculation step, the temperature T(° C.) can be converted into the Arrhenius equation factor X defined by 1/(T+273), and the lifetime L(time) is Arrhenius defined by ln(L) Can be converted to the equation factor Y. The regression analysis may include deriving a linear equation of Y = aX + b from a plurality of (X, Y) data pairs, and the activation energy of the capacitor can be calculated by multiplying the slope a of a straight line and Boltzmann constant k. have.

In the operation temperature calculation step, the deterioration weighted average temperature T _e may be calculated using Equation (1) below.

--- (1)Te =

--- (One)

φ is the activation energy (eV), k is the Boltzmann constant, t _s is the service time, t _i is the n time interval, e is the base of the natural logarithm (approximately 2.71828), and T _i is the midpoint temperature.

In the operation temperature calculation step, the operation temperature may be calculated by adding the temperature increase value to the deterioration weighted average temperature T _e calculated by Equation (1), and the temperature increase value is a capacitor device (panel) temperature rise value and a capacitor A value larger than the temperature rise value may be applied.

In the life estimation step, the following formula (2) can be used.

--- (2)ln(L) =

--- (2)

Here, L is the expected life (time) of the capacitor, φ is the activation energy (eV), k is the Boltzmann constant, T is the operating temperature (°F), and C is the process of converting the Arrhenius equation to the life equation Constant.

In the life calculation step, the life of the capacitor may be calculated by dividing the result of Equation (2) by n (a natural number greater than 1).

The capacitor life estimation device according to an embodiment of the present invention includes an activation energy calculation unit, an operation temperature calculation database unit, an operation temperature calculation unit, and a life calculation unit. The activation energy calculation unit performs a regression analysis from a database storing temperature-life information of a capacitor, a first operation unit converting temperature-life information stored in a database into an Arrhenius equation factor, and a regression analysis from the operation results of the first operation unit It includes a second calculation unit for calculating the activation energy of. The operating temperature calculation database unit stores actual ambient temperature information of the site obtained from the power plant operation information system, internal temperature information of the capacitor device obtained from the temperature measurement equipment, and heat generation temperature information of the capacitor itself. The operation temperature calculation unit includes a third calculation unit for calculating the deterioration-weighted average temperature using the information stored in the operation temperature calculation database unit, and a fourth operation unit for calculating the operation temperature from the calculation result of the third calculation unit. The life calculation unit is composed of a fifth calculation unit that calculates the life of the capacitor using the Arrhenius equation using the activation energy and the operating temperature as parameters.

According to this embodiment, by applying the deterioration-weighted average temperature (equivalent temperature) based on the actual ambient temperature, it is possible to apply a lower operating temperature than the conventional one when calculating the life, thereby extending the replacement cycle of the capacitor based on the extended life. You can. Therefore, it is possible to create economic performance by reducing purchase costs through rational engineering and maintenance efficiency improvement.

1 is a configuration diagram of a capacitor life estimation device according to an embodiment of the present invention.
2 is a flowchart illustrating a capacitor life calculation method according to an embodiment of the present invention.
3 is a graph showing an example of the regression analysis process of the first step.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein.

1 is a block diagram of a capacitor life estimation device according to an embodiment of the present invention.

Referring to FIG. 1, the capacitor life estimating apparatus 100 largely includes an activation energy calculating unit 10 for calculating activation energy of a capacitor, and an operation temperature calculation database for storing temperature information obtained from a power plant operation information system and temperature measurement equipment. The lifespan of the capacitor is calculated based on the calculation result of the unit 20, the operation temperature calculation unit 30 for calculating the operation temperature using the deterioration weighted average temperature (equivalent temperature), and the operation temperature calculation unit 30 It includes a lifetime calculation unit 40.

2 is a flowchart illustrating a capacitor life calculation method according to an embodiment of the present invention.

1 and 2, the capacitor life calculation method is largely the first step (S10) for calculating the activation energy of the capacitor, the second step (S20) for establishing a database for calculating the operating temperature, and deterioration weighting It includes a third step (S30) for calculating the operating temperature using the average temperature (equivalent temperature) and a fourth step (S40) for calculating the life of the capacitor based on the calculation result of the third step (S30).

The first step S10 is an activation energy calculation step and is executed by the activation energy calculation unit 10. The second step (S20) is a step of constructing the operation temperature calculation database unit 20. The third step S30 is an operation temperature calculation step and is executed by the operation temperature calculation unit 30. The fourth step S40 is a life calculation step, and is executed by the life calculation unit 40.

The first step (S10), the process of collecting the temperature-life information of the capacitor using the document of the manufacturer that produced the capacitor, the process of converting the temperature-life information to Arrhenius equation factors, and through regression analysis It may include the process of calculating the activation energy of the capacitor.

The activation energy calculating unit 10 includes a database storing temperature-life information of a capacitor, a first operation unit converting temperature-life information stored in the database into Arrhenius equation factors according to a preset logic, and a preset logic. Accordingly, it may be composed of a second calculation unit for calculating the activation energy of the capacitor through regression analysis.

Table 1 below shows an example of converting temperature-life information and temperature-life information of capacitors for inverters collected using the document of a capacitor manufacturer into Arrhenius equation factors (X, Y). In Table 1, X and Y are conversion factors, X is defined as 1/(T+273), and Y is defined as ln(L). Here, T is temperature (°C), and L is life (time).

3 is a graph showing an example of the regression analysis process of the first step. In the graph of FIG. 3, the horizontal axis is the conversion factor X, and the vertical axis is the conversion factor Y. Regression analysis is a well-known mathematical technique that derives a polynomial of first order or more from a plurality of (X, Y) data pairs. Equation 1 below shows an example of a formula derived by regression analysis from the graph of FIG. 3.

[Equation 1]

Y = aX + b = 7762.7X-11.793

In Equation 1, a is a slope of a straight line, and b is a constant.

The activation energy (φ) of the capacitor is defined as the product of the slope a of the straight line and the Boltzmann constant k. Equation 2 below shows an example of calculating the activation energy of the capacitor.

[Equation 2]

φ(eV) = a×k(eV) = 7762.7×8.617×10 ^-5 = 0.668913706

The second step (S20) is a process of acquiring the actual ambient temperature at the power plant site using a power plant operation information system (hereinafter referred to as a'PIS'), and using the calibrated temperature measurement equipment inside the capacitor device. And obtaining temperature and self-heating temperature information.

Through this process, the operation temperature calculation database unit 20 is built, and the operation temperature calculation database unit 20 stores temperature information acquired from the PIS and temperature information acquired from the temperature measurement equipment.

Since the ambient temperature of the capacitor affects the temperature rise and thermal aging of the capacitor device and components, it is very important to obtain actual temperature data around the capacitor. In this embodiment, the ambient temperature is obtained from the PIS, and the internal temperature of the capacitor device and the heating temperature of the capacitor itself are obtained from the temperature measurement equipment.

Table 2 below shows examples of data obtained by measuring actual field temperature. In Table 2, the panel is a panel of a device or component in which a capacitor is installed, and the panel temperature (internal temperature) is used in the same sense as the temperature of the capacitor device (internal temperature).

The actual field temperature measurement consists of measuring the room temperature where the panel is installed, the internal temperature of the panel, and the surface temperature of the capacitor. The room temperature can be obtained from the PIS, and the internal temperature of the panel and the surface temperature of the capacitor can be obtained from the temperature measurement equipment. In Table 2, the panel temperature rise value is the panel internal temperature minus the room temperature, and the capacitor temperature rise value is the surface temperature of the capacitor minus the panel internal temperature.

The third step (S30) includes the process of calculating the deterioration-weighted average temperature (equivalent temperature) based on PIS data and capacitor properties, and calculating the operating temperature by replacing the calculated equivalent temperature with the actual ambient temperature. can do. The operation temperature calculating unit 30 may be composed of a third operation unit for calculating the deterioration weighted average temperature according to the preset logic and a fourth operation unit for calculating the operation temperature according to the preset logic.

If the value obtained by a simple arithmetic method for the measured operating temperature is the average temperature, the deterioration-weighted average temperature (equivalent temperature) is based on the Arrhenius thermal model, and the temperature changes over time and the properties according to the temperature changes. It means the temperature calculated by reflecting the data on the change.

Equation 3 below shows an example of calculating the deterioration weighted average temperature (T _e ).

[Equation 3]

= 22.42℃T _e =

= 22.42℃

Here, φ is the activation energy (eV), k is the Boltzmann constant, t _s is the service time, t _i is the n time interval, e is the base of the natural logarithm (approximately 2.71828), and T _i is the midpoint temperature.

The operating temperature can be calculated by adding the temperature increase to the deterioration-weighted average temperature (T _e ). Here, the temperature rise value may be applied to the value of the panel temperature rise and the capacitor temperature rise shown in Table 2, and when applying a conservative criterion, a value greater than the value of the panel temperature rise and the capacitor temperature rise may be applied. .

For example, the operating temperature may be calculated as an equivalent temperature of 22.42°C plus the temperature rise of the panel and capacitor (3.2°C+2°C = 5.2°C) (27.62°C). On the other hand, when the conservative standard is applied, the operating temperature can be calculated as 32.42°C by applying the equivalent temperature of 22.42°C and the temperature rise of 10°C.

The fourth step (S40) is a process of calculating the life of the capacitor using the Arrhenius equation as the activation energy and the operating temperature as parameters. The life calculation unit 40 may be configured as a fifth operation unit that calculates the life of the capacitor according to a preset logic using the Arrhenius equation with the activation energy and the operating temperature as parameters.

Equation 4 below shows an example of capacitor life estimation.

[Equation 4]

ln(L) =

Here, L is the expected life of the capacitor, φ is the activation energy, k is the Boltzmann constant, T is the operating temperature (°F), and C is the constant generated in the process of converting the Arrhenius equation to the lifespan equation.

The result of Equation 4 can be calculated as the expected life of the capacitor, or by applying a conservative criterion, a value less than the result of Equation 4 can be calculated as the expected life. For example, the expected life of a capacitor can be calculated by dividing the result of Equation 4 by n (a natural number greater than 1).

For example, the activation energy (0.668913706eV) of the capacitor calculated in the first step (S10) and the operating temperature (32.42°C) calculated in the third step (S30) are applied to Equation 4, and conservative criteria are applied. By dividing the result of Equation 4 by 3, approximately 30.93 can be estimated as the expected lifetime.

In the related art, the processes of the first to third steps are omitted, and the life of the capacitor is calculated by applying the operating temperature of the capacitor to 40°C. In this case, the estimated lifetime is approximately 16.98 years, which is approximately half of the 30.93 years calculated in this example. This is due to the excessive application of the heat aging condition by applying an excessively high operating temperature in the conventional life calculation method.

In the method of this embodiment, by applying the deterioration weighted average temperature (equivalent temperature) based on the actual ambient temperature, it is possible to apply a lower operating temperature than the conventional one when calculating the life, and accordingly, the replacement cycle of the capacitor can be extended based on the extended life. have. Therefore, it is possible to create economic performance by reducing purchase costs through rational engineering and maintenance efficiency improvement.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to carry out various modifications within the scope of the claims and detailed description of the invention and the accompanying drawings. It is natural to fall within the scope of.

100: capacitor life calculation device
10: activation energy calculation unit
20: Operation temperature calculation database
30: operating temperature calculation unit
40: Life calculation

Claims (7)

An activation energy calculation step of collecting temperature-life information of the capacitor, converting the collected temperature-life information to an Arrhenius equation factor, and calculating activation energy of the capacitor through regression analysis;
An operation temperature calculation database unit construction step of acquiring the actual ambient temperature at the site from the power plant operation information system and obtaining and storing the internal temperature of the capacitor device and the self-heating temperature of the capacitor from the temperature measurement equipment installed in the capacitor device;
An operation temperature calculating step of calculating a deterioration weighted average temperature based on data of the operation temperature calculation database unit and a capacitor property, and calculating an operation temperature by replacing the calculated deterioration weighted average temperature with an actual ambient temperature; And
And a life estimating step of estimating the life of the capacitor using the Arrhenius equation using the activation energy and the operating temperature as parameters. According to claim 1,
In the step of calculating the activation energy,
The temperature T (° C.) is converted to the Arrhenius equation factor X defined by 1/(T+273), and the lifetime L (time) is converted to the Arrhenius equation factor Y defined by ln(L),
Regression analysis involves deriving a linear equation of Y = aX + b from a plurality of (X, Y) data pairs, and the capacitor's activation energy is calculated by multiplying the slope a of the straight line by Boltzmann's constant k. Way. According to claim 2,
In the operation temperature calculation step,
The deterioration weighted average temperature (T _e ) is a capacitor life calculation method calculated using the following equation (1).
Te =

--- (One)
φ is the activation energy (eV), k is the Boltzmann constant, t _s is the service time, t _i is the n time interval, e is the base of the natural logarithm (approximately 2.71828), and T _i is the midpoint temperature. According to claim 3,
In the operation temperature calculation step,
The operating temperature is calculated by adding the temperature increase to the deterioration weighted average temperature (T _e ) calculated by Equation (1),
The temperature rise value is a capacitor device (panel) temperature rise value and the capacitor temperature increase value is greater than the value applied to the capacitor life calculation method. The method of claim 4,
In the step of calculating the life,
The method of calculating the life of a capacitor in which the following formula (2) is used.
ln(L) =

--- (2)
Where L is the expected life (time) of the capacitor, φ is the activation energy (eV), k is the Boltzmann constant, T is the operating temperature (°F), and C is the process of converting the Arrhenius equation to the life equation Constant. The method of claim 5,
In the step of calculating the life, the life of the capacitor is calculated by dividing the result of Equation (2) by n (a natural number greater than 1). The activation energy of the capacitor is performed by performing a regression analysis from the database storing the temperature-life information of the capacitor, the first operation unit converting the temperature-life information stored in the database to the Arrhenius equation factor, and the calculation results of the first operation unit. An activation energy calculator including a second calculator to calculate;
An operating temperature calculation database unit that stores actual ambient temperature information of the site obtained from the power plant operation information system, internal temperature information of the capacitor device obtained from the temperature measurement equipment installed in the capacitor device, and self-heating temperature information of the capacitor;
A driving temperature calculation unit including a third calculation unit for calculating a deterioration-weighted average temperature using information stored in the operation temperature calculation database unit, and a fourth calculation unit for calculating an operation temperature from the calculation result of the third calculation unit; And
A capacitor life calculation device comprising a life calculation unit comprising a fifth calculation unit for estimating the life of a capacitor using the Arrhenius equation using the activation energy and the operating temperature as parameters.

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