JP2924987B2 - Gas leak detection method for gas insulated switchgear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting gas leakage in a gas insulated switchgear.

[0002]

2. Description of the Related Art Conventionally, gas-insulated switchgear (GIS) has been
Is formed by a plurality of gas sections of the metal container component enclosing sealed F ₆ gas, the gas leakage at these gas compartment occurs, the withstand voltage becomes dangerous operating condition decreases.

[0003] Therefore, conventionally, by comparing the gas pressure at a predetermined time every day with the gas pressure at the same time the previous day or monitoring a change in the gas pressure, a standard for detecting a gas leak whose gas pressure corresponds to the working limit pressure of the GIS is conventionally used. Gas leaks are detected when the pressure drops, alarms are issued, and countermeasures are taken to avoid dangerous situations.

[0004]

In the case of the conventional GIS gas leak detection, the gas leak is not detected until the gas pressure actually decreases to the GIS service limit pressure. And
The change in the pressure drop of the GIS gas pressure due to the gas leak differs depending on the state of the leak. The gas pressure decreases gradually in the case of spontaneous leakage, but the gas pressure sharply drops in the case of a sudden leak.

Therefore, even if the gas pressure is reduced to the reference pressure and a gas leak is detected, there is a problem that an appropriate countermeasure cannot be taken depending on the tendency of the pressure reduction and the like. When they occur, measures may be delayed.

SUMMARY OF THE INVENTION It is an object of the present invention to detect a gas leak in a gas section of a GIS at an early stage by predicting a time at which a gas pressure falls to a reference pressure for detecting a gas leak. It is also an object of the present invention to enable accurate detection.

[0007]

Means for Solving the Problems To achieve the above object, a gas leak detection method for a GIS according to the present invention comprises:
The gas pressure in the gas section of the GIS is periodically detected and monitored, and the detected pressure is set at each of the pressures P ₁ ′ at a predetermined caution stage.
'Detects, each pressure _{P 1'} to P 'time _{t 1} was lowered to' _n ~t _n to P _n ', the time _{t 1'} the ~t _n 'time function expression of decompression changes following 6 Substituting into the gas pressure P ′ and the time t ′, a simultaneous equation of each of the pressures P ₁ ′ to P _n ′ is established, and an initial pressure P which varies depending on gas leakage of the time function equation by a constant determination operation using the established simultaneous equation. _m ', initial time t
_O ', the time constant T' determines the value of each constant of, to P n _'lower gas leakage detecting these values' each pressure P ₁ in the' gas pressure P as well as substituted into the constant of the time function formula _'from the following equation (7) formula that by substituting deforming the time function formula, the gas pressure P' of the reference pressure P _L Request is _'time t _L to decrease _the' reference pressure P _L. However, it is assumed that n ≧ 3.

[0008]

[6] _{P '= P m' · exp} {- (t'-t O ') / T'}

[0009]

[Equation 7] _{t L '= t O' -T} '· Ln (P L' / P m ') Ln: operator that shows the natural logarithm

Further, when achieving the improvement of detection accuracy, the gas pressure of the gas compartment of the gas insulated switchgear monitored periodically detected, the detected pressure P _i at time i by conversion formula below Number 8 Converted to the converted pressure P _si of the reference temperature s, the converted pressure P
Each pressure P at the caution stage of the reference temperature s where _si is a preset temperature
_The times t _{1 to} t _{n at} which the pressure P falls to _{1 to} P _n are detected, and each pressure P
_{1 to} P _n and the respective times t _{1 to} t _n are substituted into the gas pressure P and the time t of the time function formula of the decompression change of the following equation 9 to obtain the respective pressures P ₁ to
A simultaneous equation of P _n is established, and values of respective constants of an initial pressure P _m , an initial time t _O , and a time constant T, which are different due to gas leak of the time function, are determined by a constant determination operation using the established simultaneous equation, these values by substituting the reference pressure PL in the pressure P ₁ to P _n lower gas leak detection in gas pressure P as well as substituted into the constant of the time function formula number 10 which is a modification of the time function formula from equation to determine the time t _L of the gas pressure P in which the influence of outside air temperature is lowered to the reference pressure PL. However, it is assumed that n ≧ 3.

[0011]

P _si = P i + L · (s−Ti) P _si : Converted pressure at i (kgf / cm ² · g) P _i : Detected pressure at _i (kgf / cm ² · g) T _i : i Temperature of outside air at time (° C) L: Gas density coefficient (kgf / cm ² · g / ° C)

[0012]

P = P _m · exp {− (t−t _O ) / T}

[0013]

T _L = t _O −T · _{L n} (P _L / P _m ) Ln: operator indicating natural logarithm

[0014]

In the gas leak detecting method of the GIS according to the present invention configured as described above, in claim 1, it is assumed that the gas pressure in the gas compartment is reduced by the gas leak according to the time function equation (6). based on the detection of the gas pressure time t ₁ (detected pressure) is lowered to the pressure P _{1 '~P} n' attention stage that has been set in advance _'~t n', the pressure P ₁ '~
The simultaneous equations of the pressures P ₁ ′ to P _n ′ are established by substituting P _n ′ and the times t ₁ ′ to t _n ′ into the time function formula of Expression 6.

The values of the initial pressure P _m ′, the initial time t _O ′, and the time constant T ′, which are different due to the gas leak of the time function equation of Equation 6, are determined by the constant determination operation using the established simultaneous equations. Is determined.

Further, these values are substituted into the respective constants of the time function equation of the equation (6), and the equation (7) is obtained by substituting the gas pressure P 'with the reference pressure P _L ' for gas leak detection.
A time t _L ′ at which the pressure falls to the reference pressure P _L is obtained.

Therefore, the time t _L ′ at which the pressure falls to the GIS use limit pressure is predicted in advance, and the gas leak of the GIS is detected early.

[0018] In the case of claim 2, in terms of the pressure P of the reference temperature s by conversion formula having 8 to detect the pressure P _i at each time i
Each pressure Caution stages with in terms of the _si is set to the pressure P ₁ to P _n of the respective reference temperature s, number 9, the operation of the numerical formula 10, a reference pressure P _L of the gas pressure P gas leak detection
Time t _L to decrease sought, performed accurately early detection of gas leakage by eliminating the influence of the outside temperature.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. FIG. 2 shows a configuration in which the present invention is applied to the detection of gas leaks in a plurality of gas sections of the GIS. The gas pressure in each section is constantly detected by each of the pressure sensors 1a,.

Further, in order to eliminate the fluctuation of the detected pressure due to the outside temperature (atmosphere temperature), the outside temperature sensor 2
Outside temperature is constantly detected.

An analog signal of the detected pressure of each section of the pressure sensors 1a to 1n and the detected temperature of the outside air temperature sensor 2 is transmitted to a detecting device 3 provided on a monitoring panel or the like, and an input insulating device of the device 3 is provided. The signal is supplied to a multiplexer 6 via an amplifier section 4 and a low-pass filter section 5 for removing unnecessary bands.

The multiplexer 6 supplies analog signals of the detected pressure and detected temperature of each section to an A / D converter 7 to convert them into digital data, and supplies these digital data to an arithmetic processing unit 8 having a microcomputer configuration. I do.

Then, the arithmetic processing unit 8 operates as described below. First, the instantaneous detected pressure of each section is converted into the pressure of the reference temperature s such as 20 ° C. based on the latest data of the outside air temperature and calibrated to eliminate the influence of the outside air temperature.

At this time, the conversion formula of the detected pressure of each section is:
For example, when the reference temperature s is 20 ° C., the following equation 11 is used.

[0025]

P 2 _Oi = P _i + L · (20−T _i ) P 2 _Oi : 20 ° C. converted pressure at the time of i (kgf / cm ² ·
g) P _i : Detection pressure at _i (kgf / cm ₂ · g) T _i : Outside air temperature at _i (° C.) L: Gas density coefficient (kgf / cm ² · g / ° C.)

Next, the times t _{1 to} t _{n at} which the calibrated detected pressures of the respective sections decrease to the preset pressures P _{1 to} P _n in the caution stage are detected. The pressure _P 1 to P _n is a set pressure at the respective reference temperature.

Assuming that the detected pressure of each section from which the influence of the outside air temperature is excluded is a gas pressure P, the gas pressure P is an index according to the solid line in FIG. Functionally degraded.

At this time, the initial pressure P _m , the initial time t _O , and the time constant T in the equation (9) are constants different depending on gas leakage. If the values of these constants are determined, the gas pressure can be calculated from the equation (9). Predict a decrease in P.

[0029] Then, the reference pressure of the converted gas leak detection reference temperature used corresponds to the critical pressure, such as GIS, as shown in FIG. 1 and P _L, the attention stage of gas leakage of a preset reference temperature The pressure is set to P ₁ , P ₂ ,..., Pn (P ₁ <
P ₂ <... P _n <P _L ), and the gas pressure P is set at each of the pressures P ₁ to P ₁ .
Time _t 1 when reduced to P _{n, t} 2, ... to detect tn, gas pressure P number 9 wherein the time t to the pressure _P 1 _{to P} n,
Substituting the times t _{1 to} t _n , the pressure P _{1 in the following} equation 12 is obtained.
A simultaneous equation of ~ _Pn is established. However, it is assumed that n ≧ 3.

[0030]

P ₁ = P _m · exp ｛− (t ₁ −t _O ) / T｝ P ₂ = P _m · exp ｛− (t ₂ −t _O ) / T｝ Pn = P _m · exp ｛− (T _n −t _O ) / T｝

If the calculation of the coefficients of the non-linear function (non-linear regression parameter) using the simultaneous equations of equation (12) or the solution operation of the so-called simultaneous equations is executed as the constant determining operation, the constant determining equation Unknown constant P in the equation
_m . t _O. The value of T is determined and determined, and the time function formula of Expression 10 is determined.

Then, P = P
When calculated as P _L, prior to lowering the reference pressure _{P L,}
The time t _{L at} which the pressure P _L is reduced is obtained.

When the time t _L is known, the time t _L
To grasp the trend, etc. of the vacuum change based on the gas leakage from the length or the like of time of up to _L, gentle natural leakage, even in the event any of the sharp sudden leakage, to know the time t _L to be subjected to pre-measures, Thorough measures can be taken.

Therefore, the arithmetic processing unit 8 sets the detected pressure after calibration as the gas pressure P for each gas section based on the preset pressures P _{1 to} P _n of the common or individual caution stages of each section. The pressure comparison and the time detection of 3 are executed.

[0035] Then, when the detected pressure detected time _t 1 ~t _n when lowered to the pressure _P 1 to P _n, constant _P m running constant determination operation of _{the, t} O, the value of T after determining to perform the equation calculation of the number 10 to determine the time t _L of each compartment.

Furthermore, the time _{t L} to decrease the time _t 1 ~t _n and the reference pressure _{P L} drops in pressure _P 1 to P _n of each compartment
The results of monitoring and detection are supplied to the display unit 9 and displayed on a screen as numerical values or a characteristic graph as shown in FIG.
The data is supplied to an external storage device or the like via the data transmission unit 10 and managed.

When the time t _L is reached, a contact signal for alarm is supplied to an external alarm device or the like via the contact output unit 11.

In the above embodiment, the detected pressure is converted into the pressure at the reference temperature (20 ° C.) to determine the time t _L ,
Even when the gas pressure in each section changes steadily depending on the gas temperature, early detection of gas leakage can be accurately performed early by eliminating the influence of the outside air temperature.

By the way, when the change of the gas pressure depending on the temperature is small, it may be detected without the calibration based on the outside air temperature. In this case, each of the pressures at the caution stage is P ₁ ′ to P _1
n ′, the time when the detected pressure decreases to these pressures P ₁ ′ to P _n ′ is _denoted by t ₁ ′ to t _n ′, and the expressions of Expressions 6 and 7 are used instead of Expressions 9 and 10. Gas pressure P 'is the reference pressure P
_The time t _L ′ at which the temperature falls to _L ′ may be obtained.

Then, each pressure P ₁ ′-
The number and value of P _n ′, P _{1 to} P _n may be set according to the type of gas and usage conditions.

Next, a specific example in which the present invention is applied to detection of gas leakage of a so-called reduced GIS will be described.

In the case of a reduced type GIS having a rated pressure of 5.0 kgf / cm ² · g, an alarm pressure for gas leakage is 4.5 kgf / cm ^2.
cm ² · g, so that the reference pressure P _L ′ for gas leak detection without correction due to the outside air temperature is 4.5 kgf / cm ² · g
And

Then, the number n of caution stages is set to 3, and the pressure P ₁ ′ of the _first caution stage is 4.95 kgf / cm ² · g,
Pressure P ₂ ′ at second caution stage = 4.90 kgf / cm
² · g, pressure P ₃ ′ at the _third caution stage = 4.85 kg
f / cm ² · g and the detection was started with t _O ′ = 0, the gas pressure of GIS was 0.1 hours later (t
₁ ′ = 0.1), decreases to P ₁ ′, 0.2 hours later (t ₂ ′ = 0.2), P ₂ ′ and 0.3 hours later (t ₃ ′ = 0.3) ) To P ₃ ′.

In this case, based on the pressures P ₁ ′, P ₂ ′, P ₃ ′ and the times t ₁ ′, t ₂ ′, t ₃ ′, the initial pressure Pm ′ = 5. 0 kgf / cm ² · g and a time constant T ′ = 10 hours are obtained. As shown in the following equation (13), the gas pressure of the GIS starts to leak (t _O ′ = 0) and after about one hour from the reference pressure P _L ′ = 4.5 kgf / cm ²
-The decrease to g can be detected in advance.

[0045]

T _L ′ = t _O ′ −T ′ · L _n (P _L ′ / P _m ′) = 0−10 · L _n (4.5 / 5.0) ≒ 1.05 (hour)

[0046]

Since the present invention is configured as described above, the following effects can be obtained. First, in the case of claim 1, the time t ₁ ′ when the gas pressure (detection pressure) of the gas section of the gas insulated switchgear (GIS) drops to each of the pressures P ₁ ′ to P _n ′ in a preset caution stage. Ｔt _n ′ based on the detection of the pressures P ₁ ′ 〜P _n ′ and the times t ₁ ′ 't _n ′
Is substituted into the time function formula of the decompression change of Equation ₁ to obtain the pressure P ₁ ′ ~
A simultaneous equation of P _n ′ is set up (where n ≧ 3), and an initial pressure P _m ′ and an initial time t _O ′ that differ depending on the gas leak of the time function equation by a constant determination operation using the established simultaneous equation. , the time constant T 'determines the value of each constant of, as well as substitutes the determined values of the constants in the time function formula, the gas pressure P' is deformed by substituting the reference pressure P _{L 'of} gas leak detection From equation (2), the time t when the pressure falls to the reference pressure P _L ′
_{Since L} ′ has been obtained, the time t _L ′ at which the gas reaches the GIS use limit pressure due to gas leakage can be predicted in advance and detected early, and the pressure reduction based on the gas leakage can be performed from the time until this time t _L ′. Understand the gradual and sudden changes, etc.
Appropriate measures can be taken against the various types of gas leaks.

[0047] In the case of claim 2, in terms of the pressure P of the detected pressure P _i the reference temperature s by the number 3 in the conversion formula for each time i
converts to _si, the pressure of each note stage to set set pressure P ₁ to P _n of the reference temperature s respectively, the number 4, from the numerical formula 5, the gas pressure P is the reference pressure in which the influence of outside air temperature because of obtaining the time t _L to decrease the P _L, it can be performed more accurately GIS gas leakage early detection of eliminating the influence of ambient temperature.

[Brief description of the drawings]

FIG. 1 is a decompression characteristic diagram for explaining detection of one embodiment of a gas leak detection method for a gas insulated switchgear of the present invention.

FIG. 2 is a block diagram of an apparatus used for detection in FIG.

FIG. 3 is a flowchart for explaining processing of an arithmetic processing unit in FIG. 2;

[Explanation of symbols]

P gas pressure P _m initial pressure P ₁ to P each pressure of _n Note stage P _L reference pressure t _O initial time t ₁ ~t _n P ₁ to P _n time t _L the time to decrease the P _L of

Claims (2)

(57) [Claims] 1. A gas pressure in a gas section of a gas insulated switchgear is periodically detected and monitored, and a time t ₁ at which the detected pressure falls to each of pressures P ₁ ′ to P _n ′ at a predetermined caution stage. '
'Detects the respective pressure _{P 1' ~t n ~P n '} , the respective times _{t 1'} ~t _n '
Is substituted for the gas pressure P ′ and the time t ′ of the time function formula of the pressure change of the following equation (1) to establish simultaneous equations of the respective pressures P ₁ ′ to P _n ′, and a constant determination operation using the established simultaneous equations by the time function formula of the gas leakage by different initial pressure P _m ', initial time t _O', when determining the values of the constants in the constant T ', substituted into these values to the respective constant of the time function formula In addition, the gas pressure P ′ is substituted with the reference pressure P _L ′ for gas leak detection lower than each of the pressures P ₁ ′ to P _n ′, and the time function formula is transformed into the following equation (2). A gas leak detection method for a gas insulated switchgear, wherein a time t _L ′ at which P ′ falls to the reference pressure P _L ′ is obtained. However, it is assumed that n ≧ 3. [Number 1] _{P '= P m' · exp} {- (t'-t O ') / T'} Equation 2] _{t L '= t O' -T} '· Ln (P L' / P m ' Ln: operator indicating natural logarithm Wherein monitoring the gas pressure of the gas compartment of the gas insulated switchgear is detected periodically, converting the detected pressure P _i at time i in terms of the pressure P _si reference temperature s by conversion formula the following equation 3 and, wherein the reduced pressure _{P si} time is decreased to the pressure _P 1 to P _n of the attention stage preset the reference temperature s _t 1 ~t _n
Detects said each pressure _P 1 to P _n, each time _t 1 ~t _n the gas pressure P of the time function type vacuum change the following equation 4, the by substituting the time t the pressure _P 1 to P making a simultaneous equation of _n, erected <br/> initial pressure varies by a gas leakage of the time function formula by constant determining operation using the simultaneous equations P _m, the values of the constants of the initial time t _O, the time constant T determined, substitutes a reference pressure P _L of these values before <br/> Symbol time function formula of the said respective pressure P ₁ to P _n lower gas leak detection on the gas pressure P as well as substituted into the constants The gas pressure P excluding the influence of the outside air temperature is obtained from the following equation (5) obtained by modifying the time function equation.
Determining a time t _{L at} which the pressure decreases to the reference pressure P _L. However
And n ≧ 3. P _si = P _i + L · (s−T _i ) P _si : Converted pressure at i (kgf / cm ² · g) P _i : Detected pressure at _i (kgf / cm ² · g) T _i : outside air temperature at the time of i (° C.) L: gas density coefficient (kgf / cm ² · g / ° C.) P = P _m · exp {− (t−t _O ) / T} _{t L = t O -T · Ln} (P L / P m) Ln: operator that shows the natural logarithm