JPH11230847A - Device for monitoring pressure of gas for electrical insulation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten processing time at the time of calculating temperature compensating pressure in a pressure state monitoring device of an electrically insulating gas to monitor the pressure of a gas for electrical insulation, by calculating temperature compensating pressure on the basis of the detected pressure and detected temperature of the gas for electrical insulation. SOLUTION: The coefficients of a plurality of constant molar volume curves on a plurality of molar volumes corresponding to a plurality of pressures from the vicinity of the high pressure-side control limit of an SF6 gas to the vicinity of the low pressure-side control limit are stored in the storage unit 45 of a control part 24. At an initial state, the coefficients of two constant volume curves in the vicinity of the high pressure-side control limit, and in the vicinity of the low pressure-side control limit, are selected. For a first time, temperature compensating pressure is obtained from the pressure of the gas detected at a pressure detecting part 21, the temperature of the gas detected at a temperature detecting part 22, and the selected coefficients. For a second time or later, the coefficients of two constant molar volume curves sandwiching the temperature compensating pressure obtained at the previous time are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates a temperature compensation pressure, which is a pressure at a predetermined reference temperature, based on a detected pressure and a detected temperature of an electrically insulating gas sealed in a pressure vessel. A pressure monitoring device for monitoring the pressure of the gas for electrical insulation based on, for example, a gas-insulated switchgear in the field of electric power (hereinafter, referred to as
GIS: GasInsulated Switchgear. ), Gas insulated transmission line (hereinafter, GIL: Gas Insulated transmission)
Line. ) And gas insulated transformer
sulfur hexafluoride gas (S)
The present invention relates to a pressure state monitoring device for an electric insulating gas suitable for monitoring the pressure state of a gas excellent in electrical insulation, non-combustibility, and non-corrosion, such as F ₆ gas. In the following description, the electrical equipment in which the gas is sealed is generically called GIS,
In addition, gas and gas have the same meaning.

[0002]

2. Description of the Related Art In general, a gas excellent in electrical insulation is sealed in a GIS through which a high-voltage current flows. Various electrical phenomena occur in the GIS. To detect the electrical phenomena, detection means such as voltage detection, current detection, temperature detection, pressure detection, sound detection, and light detection are used. Phenomena are detected, the state inside the GIS is monitored based on the detected various signals, and continuation / stop of the operation of the GIS is determined and controlled. Since the practical use of GIS, a method of monitoring the state of the inside of the GIS using a means for detecting the gas pressure inside the GIS as the detection means has been described.
Extremely effective and heavily used. It is a widely known fact that SF ₆ gas is often used as a gas having excellent electrical insulation properties, including the example disclosed in Japanese Patent Publication No. 6-40045. On the other hand, Tokiko Sho 61-45
The gist disclosed in Japanese Patent Publication No. 766 is that "the gas of the power circuit breaker is an extinguishing gas, and the pressure-temperature characteristics of the gas are stored as a non-linear curve in the memory."
That is. BACKGROUND ART-2 In recent years, various measures have been taken as a social responsibility in various technical fields to protect the global environment, or improvements in technology have been studied. In particular, at the 3rd Conference of the Parties to the United Nations Framework Convention on Climate Change (COP3), which was held in 1997 to discuss the reduction of greenhouse gas emissions, the so-called “Kyoto Conference”, the emission reduction of “SF ₆ gas” to the atmosphere was reduced. It has been demanded. As an interim measure, the use of other insulating gases is being considered, although the insulation is inferior to that of "SF ₆ gas" in terms of reducing the amount of use, that is, the so-called total amount regulation.
Specifically, it is an electrically insulating gas such as "nitrogen gas" occupying about 78% of the volume of the atmosphere and "argon gas" occupying about 1% of the volume of the atmosphere. On the other hand, research and development on the discovery of the invention of “SF ₆ alternative gas” as a permanent measure has been conducted, and the results and practical application are expected.

Conventionally, as a gas state monitoring technique in GIS or the like, there is a technique using a mechanical temperature compensation pressure switch (so-called density switch) as disclosed in Japanese Utility Model Laid-Open No. 59-9450, for example. The temperature compensating pressure switch generates a gas leak alarm signal when the gas gradually leaks from the GIS and the temperature compensating pressure decreases and reaches a predetermined low pressure side threshold pressure (low pressure side set value). It is configured.

However, such a mechanical type temperature compensating pressure switch has a problem in operation reliability and accuracy. For example, as disclosed in Japanese Patent Publication No. 6-40045, a microcomputer is used. Electronic temperature-compensated pressure relays have been proposed. This temperature-compensated pressure relay detects the pressure and temperature of the gas in the pressure vessel, and sequentially uses the slopes of the plurality of constant density straight lines stored in the memory and the detected gas temperature to sequentially determine the plurality of gas pressures. From the calculated gas pressures, a constant density straight line corresponding to the gas pressure closest to the detected gas pressure is selected. Then, the temperature compensation pressure at the reference temperature is calculated using the slope of the selected constant density line and the detected gas pressure and temperature.

[0005]

More specifically, in this conventional temperature-compensated pressure relay device, the slope values of a plurality of constant density straight lines are stored in correspondence with the index I. Then, the gas pressure and the temperature are detected, and the pressure is obtained from the constant density straight line and the detected temperature while sequentially increasing the value of I starting from I = 0, so that this pressure becomes closest to the detected gas pressure. Is selected as the optimal constant density line. Then, temperature compensation calculation (20 ° C. conversion of pressure value) is performed based on the selected constant density straight line. As described above, in the conventional temperature-compensated pressure relay device, the calculation process for selecting the slope of the constant-density line used for the calculation is repeatedly performed each time the gas pressure is detected and the temperature-compensation calculation is performed. However, there is a problem that the processing becomes complicated and the processing takes time.

In the gas state monitoring technology in GIS or the like, in addition to the above-described temperature compensation pressure calculation processing,
It is necessary to perform processing for transmitting the temperature compensation pressure, processing for controlling the output of the high-pressure alarm, processing for detecting the rate of pressure rise, and the like. Performing a self-diagnosis or the like is also useful for improving reliability. That is, in order to perform such various kinds of processing by one microcomputer (8 bits), it is required to perform various kinds of processing as fast as possible.

The present invention relates to a pressure compensating state monitoring apparatus for monitoring a pressure of an electric insulating gas by calculating a temperature compensating pressure based on a detected pressure and a detected temperature of the electric insulating gas. It is another object of the present invention to reduce the processing time when calculating the value.

[0008]

According to a first aspect of the present invention, there is provided an apparatus for monitoring the pressure state of an electrically insulating gas, comprising the steps of: detecting a predetermined pressure and a detected temperature of the electrically insulating gas sealed in a pressure vessel; A pressure compensating pressure which is a pressure at a reference temperature; and a pressure state monitoring device for the electric insulating gas which monitors the pressure of the electric insulating gas based on the temperature compensated pressure. Using a plurality of constant molar volume curves for a plurality of molar volumes corresponding to a plurality of pressures from the vicinity of the limit to the vicinity of the low pressure side control limit, temperature data corresponding to the detected temperature, pressure data corresponding to the detected pressure , 2 of the plurality of constant molar volume curves
A step of calculating the temperature compensation pressure from the two constant molar volume curves, wherein two constant molar volume curves used in the first temperature compensation pressure calculation at the time of activation of the pressure state monitoring device are set in advance. Using the constant molar volume curve, as two constant molar volume curves used for the second and subsequent temperature compensation pressure calculations, two adjacent two molecules sandwiching the temperature compensation pressure value obtained as a result of the previous temperature compensation pressure calculation It is characterized in that a constant molar volume curve is selected.

According to the pressure monitoring apparatus for an electrically insulating gas according to the present invention, the temperature compensation pressure is calculated from the temperature data corresponding to the detected temperature and the pressure data corresponding to the detected pressure. In the two constant molar volume curves, the two adjacent constant molar volume curves sandwiching the value of the temperature compensation pressure obtained as a result of the previous temperature compensation pressure calculation are selected in the second and subsequent temperature compensation pressure calculations. Therefore, when there is little change in the temperature compensation pressure, in most cases, the same two constant molar volume curves as in the previous time are used, so that it takes no time to select the constant molar volume curve, and the processing time is shortened. I do. In addition, even when the constant molar volume curve is selected again, it is almost always sufficient to select the two constant molar volume curves in the vicinity of the previous time, and the processing time is shortened. Since the value of the temperature compensation pressure (converted to a pressure value of, for example, 20 ° C.) in each constant molar volume curve is known in advance, the temperature compensation pressure obtained as a result of the previous calculation and the temperature compensation pressure known in advance are used. The constant molar volume curve can be selected only by determining the magnitude relation of

According to a second aspect of the present invention, there is provided an apparatus for monitoring the pressure state of a gas for electrical insulation, comprising the configuration of the first aspect, wherein two predetermined constant moles used for calculating the first temperature compensation pressure. The volume curves are a curve near the high-pressure control limit and a curve near the low-pressure control limit.

According to the pressure monitoring apparatus for an electrically insulating gas according to the second aspect, the following operation and effect can be obtained in addition to the operation and effect of the first aspect. Since the first temperature compensation pressure is calculated by interpolation between two constant molar volume curves, the accuracy is better as compared with the case where two constant molar volume curves adjacent to each other with the temperature compensation pressure interposed therebetween are used. However, an average accuracy can be obtained as the first calculation result.

According to a third aspect of the present invention, there is provided an apparatus for monitoring the pressure state of a gas for electrical insulation, comprising the configuration of the first or second aspect, wherein the constant molar volume curve includes a detection lower limit temperature of the detection temperature and a detection lower limit temperature. The constant molar volume curve in each section is divided into a plurality of sections within the range of the upper limit temperature and is approximated by a polygonal line assuming that the curve is a straight line. Is calculated.

According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the constant molar volume curve is approximated by a broken line. Since the temperature compensation pressure can be calculated using a linear equation, the processing time is further reduced.

According to a fourth aspect of the present invention, there is provided an apparatus for monitoring a pressure state of a gas for electrical insulation, comprising the configuration of the first or second aspect, wherein the temperature compensation pressure is calculated by a microcomputer. The coefficient of the constant molar volume curve is stored in a storage means.

According to the pressure monitoring apparatus for electric insulating gas according to the fourth aspect of the present invention, in addition to the function and effect of the first or second aspect, when a constant molar volume curve is selected, It is only necessary to read out the coefficients from the storage means.

According to a fifth aspect of the present invention, there is provided an apparatus for monitoring the pressure state of an electrically insulating gas, comprising the configuration of the third aspect, wherein the microcomputer calculates the temperature compensation pressure and stores the temperature compensation pressure in a storage means of the microcomputer. It is characterized in that a coefficient of a straight line approximating a polygonal line of a constant molar volume curve is stored.

According to the pressure monitoring apparatus for an electrically insulating gas according to the fifth aspect of the present invention, in addition to the effect of the third aspect, when a straight line approximating a broken line of a constant molar volume curve is selected. It is only necessary to read the coefficient from the storage means.

According to a sixth aspect of the present invention, there is provided an apparatus for monitoring the pressure state of a gas for electrical insulation, comprising the configuration of the first, second, third, fourth or fifth aspect, wherein the constant molar volume is provided. The characteristic is that the curve is obtained in advance by solving using a virial type equation of state.

According to the apparatus for monitoring the pressure state of the gas for electrical insulation according to the sixth aspect, the function and effect of the first, second, third, fourth, or fifth aspect are achieved. In addition, the present invention can be applied to a case where an electric insulating gas or a plurality of electric insulating gases are mixed.

According to a seventh aspect of the present invention, there is provided an apparatus for monitoring the pressure state of a gas for electrical insulation, comprising the structure of the first, second, third, fourth or fifth aspect, wherein the constant molar volume is provided. The curve is previously Beattie-Bridge.
It is characterized by being obtained by solving using the equation of man.

According to the pressure monitoring apparatus for an electrically insulating gas according to the seventh aspect of the present invention, the operation and effect of the first, second, third, fourth, and fifth aspects are achieved. In addition, when SF ₆ gas is used, the constant molar volume curve becomes a constant molar volume straight line, so that a linear equation may be used to calculate the temperature compensation pressure, so that the processing time is further reduced.

In the pressure monitoring apparatus for an electric insulating gas according to the present invention, the pressure at a predetermined reference temperature is determined based on the detected pressure and the detected temperature of the electric insulating gas sealed in the pressure vessel. In a pressure state monitoring device for an electrical insulating gas for calculating a temperature compensation pressure and monitoring the pressure of the electrical insulation gas based on the temperature compensation pressure, a first pressure and a second pressure of the electrical insulation gas The temperature data corresponding to the detected temperature, the pressure data corresponding to the detected pressure, the first constant molar volume curve and the second constant molar volume curve for different molar volumes corresponding to The temperature compensation pressure is calculated by proportional distribution from the constant molar volume curve and the second constant molar volume curve.

According to the pressure monitoring apparatus for an electrically insulating gas according to the eighth aspect of the present invention, each pressure at the detected temperature of the first constant molar volume curve and the second constant molar volume curve is obtained. When calculating the temperature compensation pressure based on the detected pressure and the detected pressure, the calculation is performed by proportional distribution, so that the calculation is simplified and the processing time is shortened.

According to a ninth aspect of the present invention, there is provided a pressure state monitoring apparatus for an electrically insulating gas, comprising the configuration of the eighth aspect, wherein the range of the detected pressure for calculating the temperature compensation pressure is a straight line of the detected temperature. The first on the intersecting first constant molar volume curve
From the pressure value in the vicinity of the pressure in the range of the pressure value in the vicinity of the second pressure on the second constant molar volume curve crossing the straight line of the detected temperature.

According to the pressure monitoring apparatus for an electrically insulating gas according to the ninth aspect of the present invention, in addition to the effects of the eighth aspect, even when the temperature compensation pressure is calculated by extrapolation, Since it is close to the first constant molar volume curve or the second constant molar volume curve, a highly accurate calculation result can be obtained, and the two constant molar volume curves can be selected without being re-interpolated. Good, shortens processing time.

[0026]

Preferred embodiments of the present invention will now be described with reference to the drawings. In the description, the gas for electrical insulation is SF ₆ gas, which is frequently used. In the following, the description of the electric insulating gas using the constant molar volume curve and the description of the SF ₆ gas using the constant molar volume straight line will be described as necessary, but the curve is generally a polynomial, It is needless to say that the straight line is a linear expression and is a part of the curve, and therefore, the explanation of the temperature compensation based on the constant molar volume curve will be mainly given.

FIG. 1 is a schematic configuration diagram of an SF ₆ gas pressure state monitoring system according to an embodiment. In this embodiment, an SF ₆ gas pressure state monitoring system 1 is a gas pressure in a GIL (gas insulated transmission line). Is to monitor. G
A transmission line 2B through which a current flows at a voltage of about 30,000 to 500,000 [V] is provided in the IL 2, and the transmission line 2B is supported by an insulating spacer 2A also serving as a sealing. The space separated by the insulating spacer 2A and the GIL 2 forms independent pressure vessels 2C, respectively.
Each pressure vessel 2C is sealed with SF ₆ gas as an electric insulating gas.

The pressure condition monitoring system 1 for SF ₆ gas includes a plurality of pressure condition monitoring devices 6 as an embodiment of the pressure condition monitoring device for electric insulating gas of the present invention. Each of the pressure vessels 2C is communicated with a pressure introducing pipe 3. The SF ₆ gas pressure state monitoring system 1 includes a plurality of analog local monitoring devices 7,
A plurality of digital local monitoring devices 8, a first central monitoring device 10, a second central monitoring device 12, and an electrical equipment circuit operating section 13 are provided, and each analog local monitoring device 7 has a corresponding plurality of sets of pressures. Each of the digital local monitoring devices 8 is connected to the status monitoring device 6 via the first analog signal transmission line 4, and each of the digital local monitoring devices 8 is connected to the corresponding plurality of sets of pressure status monitoring devices 6 by the first analog monitoring device 6. Each is connected via a digital signal transmission line 5. The first central monitoring device 10 is connected to the analog local monitoring device 7 via the second analog signal transmission line 9, and the second central monitoring device 12 is connected to the digital local monitoring device via the second digital signal transmission line 11. It is connected to the device 8. Note that the electric device circuit operation unit 13 outputs various operation signals.

The pressure state monitoring device 6 receives the detected pressure, the detected temperature, and the temperature compensation pressure of the SF ₆ gas in the corresponding pressure vessel 2C as analog signals via the first analog signal transmission line 4 as an analog local monitoring device. 7, a signal such as an abnormal high pressure alarm, a pressure rise alarm or an abnormal low pressure alarm based on the detected pressure is output as digital data to the digital local monitoring device 8 via the first digital signal transmission line 5.

FIG. 2 is a schematic block diagram of the pressure state monitoring device 6. The pressure state monitoring device 6 detects the gas pressure of the SF ₆ gas in the pressure vessel 2C and outputs a pressure voltage signal, and detects the gas temperature of the SF ₆ gas in the pressure vessel 2C and detects the temperature. The apparatus includes a temperature detecting unit 22 that outputs a voltage signal, a switching setting unit 23 for setting various data and switching display, and a control unit 24 that controls the entire pressure state monitoring device 6. The display unit 25 displays alarms, various data, and units corresponding to displayed data, and transmits pressure rise detection data, abnormal high pressure detection data, or abnormal low pressure detection data to the corresponding digital local monitoring device 8. Output unit 26 for
And an analog signal transmission unit 27 for transmitting an analog signal to the corresponding analog local monitoring device 7. Further, a terminal block 28 for connecting to an external DC power supply (not shown) or corresponding local monitoring devices 7 and 8, an insulating DC / DC converter 29 for lowering the voltage of the external DC power supply to a predetermined internal power supply voltage, and A reset signal output section 30 for outputting a reset signal SRST for initializing the operation of the control section 24 by manual operation of a power switch or a reset switch (not shown).

In the middle of the pressure introducing pipe 3 connected to the pressure vessel 2C, there is provided a normally open stop valve 3A which is closed during inspection or the like and is always open during normal use. At the end of the pressure introducing pipe 3, one end is connected in series to the other end of the normally open stop valve 3A, and the other end is opened as a charge / discharge port for SF ₆ gas. 3B is provided.

The pressure detector 21 is a normally open stop valve 3A.
A gas pressure detection sensor 31 for detecting the gas pressure of SF ₆ gas and outputting an original pressure detection signal SPO between the valve and the normally closed stop valve 3B, and an original pressure voltage signal SVPO for converting the original pressure detection signal SPO to a voltage signal. And a pressure / voltage converter (P / V converter) 32 for converting the output into a signal.

The temperature detector 22 is a normally open stop valve 3A.
A gas temperature detection sensor 33 which detects the gas temperature of SF ₆ gas and outputs a raw temperature detection signal STO between the valve and the normally closed stop valve 3B, and converts the raw temperature detection signal STO to a raw temperature voltage signal SVTO which is a voltage signal. And a temperature / voltage converter (T / V converter) 34 for converting the output into a signal.

The switching setting unit 23 includes a display switching switch 35 for switching display, a setting switching switch 36 for designating setting switching, a setting unit 37 for performing various settings,
A pressure rise detection setting section 38 for inputting and setting various set values for detecting an abnormal pressure rise rate, and a manual return switch 39 for returning manually when an abnormal pressure rise rate is detected.

The control unit 24 is composed of a microcomputer or the like, and includes a control unit 40 for controlling the entire control unit 24, an operation unit 41 for performing various operations, and a comparison unit 42 for performing various comparisons. And a determination unit 43 for performing various determinations based on the comparison result in the comparison unit 42, and an A for performing analog / digital conversion of the input analog signal.
/ D converter 44, ROM for storing various data, RA
A storage unit 45 composed of an M or the like, and a timing unit 46 having a plurality of timers and outputting an interrupt signal of a timer interrupt and the like are provided. The functions of the control unit 40, the operation unit 41, the comparison unit 42, and the judgment unit 43 are realized by a CPU constituting the microcomputer and a control program executed by the CPU and described later.

The display unit 25 has a numerical display unit 50 for numerically displaying a gas temperature, a gas pressure, a temperature compensation pressure as a gas pressure at a standard temperature of 20 ° C., an abnormal pressure rise rate, and the like.
The unit includes a unit display section 51 for displaying a unit of the numerical value displayed on the numerical value display section 50, and an output display section 52 for displaying the content of the output alarm when an alarm is output.

The alarm output unit 26 is connected to the abnormal pressure rise detection relay switch 5 based on the abnormal pressure rise detection control signal SSP.
3, a pressure rise alarm output section 54 for outputting a pressure rise detection output signal SCSP, and a high pressure side alarm control signal SCSP.
A high-voltage alarm output unit 56 for outputting a high-voltage alarm output signal SCHE for driving a high-voltage alarm relay switch 55 based on HE, and a low-voltage alarm relay switch 57 based on a low-voltage alarm control signal SLE. And a low-voltage-side alarm output section 58 for outputting a low-voltage-side alarm output signal SCLE for the purpose.

The analog signal transmission unit 27 has a voltage /
Current converter (V / I converter) 62 and control unit 24
With the temperature compensation pressure voltage signal SVC electrically isolated from
An optical coupler 61 for transmitting P0, a voltage / current converter 62 for converting the temperature-compensated pressure-voltage signal SVCP1 into a temperature-compensated pressure-current signal SACP which is a current signal and outputting the same, and converting the temperature-compensated pressure-current signal SACP into four. And a first transmission signal output unit 63 that outputs a temperature-compensated pressure transmission signal STACC having a current range of ２０20 [mA]. An insulation amplifier 65 for amplifying the original pressure voltage signal SVPO and outputting it as an amplified pressure voltage signal ASVP, and a voltage / current converter 66 for converting the amplified pressure voltage signal ASVP to a pressure current signal SAP which is a current signal and outputting the same. And the pressure / current signal SAP is 4 to 20 [mA].
And a second transmission signal output section 67 which outputs the pressure transmission signal STAP having a current range of Further, an insulation amplifier 70 for amplifying the original temperature voltage signal SVTO and outputting it as an amplified temperature voltage signal ASVT, and an amplified temperature voltage signal ASV
A voltage / current converter 71 for converting T into a temperature current signal SAT, which is a current signal, and outputting the temperature / current signal SAT;
And a third transmission signal output section 72 for outputting as a temperature transmission signal STAT having a current range of 0 [mA].

The pressure state monitoring device 6 mainly performs the following processing. A plurality of pressure detection data are obtained while sampling the gas pressure at 5 msec, and an instantaneous abnormal rise is detected from the plurality of pressure detection data every 20 msec.
A sudden abnormal rise is detected every 0 msec, a slow abnormal rise is detected every 2 seconds, and a very slow abnormal rise is detected every 20 seconds. Then, the detection result is output to the digital local monitoring device 8 via the pressure rise alarm output unit 54, and the type and alarm of the abnormal rise are displayed on the display unit 25. The reference pressure rise rate for determining such an abnormal rise is determined according to the pressure rise rate at the time of various assumed accidents such as a short circuit accident or a ground fault accident. The four types of abnormal rises are set by the pressure rise detection setting unit 38 of the switching setting unit 23, respectively.

Further, the gas pressure and the gas temperature are detected to obtain a temperature compensation pressure, a high pressure abnormality and a low pressure abnormality are detected from the temperature compensation pressure, and a high pressure alarm is output from the high pressure alarm output unit 5 respectively.
6 to the digital local monitoring device 8,
The low-voltage alarm is output to the digital local monitoring device 8 via the low-voltage alarm output unit 58. The reference pressure for determining a high pressure abnormality or a low pressure abnormality is set by the setting unit 37 of the switching setting unit 23. The detected gas pressure, gas temperature, and temperature compensation pressure are output to the analog local monitoring device 7 via the analog signal transmission unit 27 and displayed on the display unit 25.

Next, a constant molar volume curve for obtaining the temperature compensation pressure from the detected temperature and the detected pressure in the pressure state monitoring device 6 will be described. The ROM of the storage unit 45 in the control unit 24 of the pressure state monitoring device 6 includes S
Coefficients of a plurality of constant molar volume curves are stored for a plurality of molar volumes corresponding to a plurality of pressures from near the high pressure side control limit to near the low pressure side control limit of the F ₆ gas. The constant molar volume curve represents the gas pressure P at a constant molar volume V as a function of the gas temperature t, and is represented by the following equation (1). The gas pressure P is set to F _i (t) in the following equation (1) for the sake of convenience described later.

[0042]

(Equation 1) In the equation (1), when the coefficients a _i2 , a _i3 ,... Of the terms larger than the second order with respect to the gas temperature t are 0, a linear equation, that is, a straight line is obtained.

In general, when an electrically insulating gas is used, for example, the Leiden type of a virial type equation of state is applied as a state equation of a real gas, and the second virial coefficient B and the third virial coefficient C are selected and substituted. The virial-type equation of state is a cubic equation for the molar volume V. here,
If we successively substituting a predetermined plurality of temperature compensation pressure P20 _i and the reference temperature 20 ° C., the virial type state equation can be solution using the "official Cardano", that determine the molar volume V it can. That is, the constant molar volume V _i
Motomari is a value, so that to sequentially obtains the plurality of constant molar volume V _i. Then, if the reverse assignment sequential plurality of the predetermined molar volume V _i to virial-type state equation can be obtained formula (1). In this case, since the second virial coefficient B and the third virial coefficient C depend on the gas temperature t, the equation (1) becomes a polynomial relating to the gas temperature t, and a constant molar volume curve is obtained.

In particular, when SF ₆ gas is used as the electric insulating gas, if the Beattie-Bridgeman equation is applied, the Beattie-Bridgeman equation becomes a cubic equation for the molar volume V. Here, if a plurality of predetermined temperature compensation pressures P20 _i and a reference temperature of 20 ° C. are substituted, the beattie
-Bridgeman's equation can be solved using "Cardano's formula", and the molar volume V can be determined. That is, Motomari the value of constant molar volume V _i, so that successively obtains a plurality of constant molar volume V _i. Then, if the reverse assignment sequential plurality of the predetermined molar volume V _i in equation Beattie-the Bridgeman, it is possible to obtain the equation (1). In this case, equation (1) becomes a linear equation related to the gas temperature t, and a straight line of constant molar volume is obtained.

Further, when "a gas obtained by mixing a plurality of electric insulating gases" is used as a measure for reducing global warming gas emissions, for example, a Leiden type virial type equation of state is applied as a state equation of a real gas. The second virial coefficient B of a two-component mixed gas, the third virial coefficient ^{_{C, B = B 11 χ 1 2}} + 2B 12 χ 1 χ 2 + B 22 χ 2 2 C = C 111 χ 1 3 + 3C 112 χ 1 2 χ 2 ^{_{+ 3C 122 χ 1 χ 2 2}} + C
Represented by ₂₂₂ chi ₂ ^3. In the formula, χ ₁ and χ ₂ are mole fractions of each component, B ₁₁ , B ₂₂ , C ₁₁₁ , and C ₂₂₂ are coefficients of pure components, and B ₁₂ , C ₁₁₂ , and C ₁₂₂ are mutual components of the mixed system. The action (cross) virial coefficient. By selecting and substituting the second virial coefficient B and the third virial coefficient C, the virial-type equation of state becomes a cubic equation for the molar volume V. Here, by sequentially substituting a plurality of predetermined temperature compensation pressures P20 _i and the reference temperature 20 ° C., the virial-type equation of state can be solved using “Cardano's formula”. You can ask. That is, the value of the constant molar volume V _i is determined, and a plurality of constant molar volumes V _i are sequentially determined.
_i will seek _i . Then, if the reverse assignment sequential plurality of the predetermined molar volume V _i to virial-type state equation can be obtained formula (1). In this case, since the second virial coefficient B and the third virial coefficient C depend on the gas temperature t, the equation (1) becomes a polynomial relating to the gas temperature t, and a constant molar volume curve is obtained.

Since it takes a very long time to process the solution of the above-described cubic equation and the inverse substitution operation in the control unit 24 of the present embodiment, it is necessary to store the result calculated in advance by a personal computer or the like in the storage unit 45. become.

In this embodiment, the pressure in the GIS pressure vessel at 20 ° C. is set to a reference pressure of 0.20 MPa.
(Megapascal), 0.30MPa, 0.40MPa,
Coefficients of seven types of constant molar volume curves which are 0.50 MPa, 0.60 MPa, 0.70 MPa, and 0.80 MPa are stored. The constant molar volume curve of 0.20 MPa is near the low pressure side control limit,
A constant molar volume curve of 0 MPa is near the high pressure side control limit. FIG. 3 is a diagram conceptually showing a coefficient table of the first embodiment in which the coefficients of the constant molar volume curve are stored. In the first embodiment, the reference pressure 0. Each coefficient a of 20 MPa to 0.80 MPa
_i0 , _ai1 , _ai2 ,... are stored. In the following description, a set of coefficients of each reference pressure is represented by A (1) to A (7) corresponding to i = 1 to 7.

In the case of a cubic type GIS, that is, C-GIS, a reference pressure of 0.00 MPa, a pressure of 0.1 MPa and a pressure of 0.0 MPa are used.
05MPa, 0.10MPa, 0.15MPa, 0.2
What is necessary is just to store the coefficients of seven kinds of constant molar volume curves such as 0 MPa, 0.25 MPa, and 0.30 MPa. In addition, in GIS or C-GIS, the constant molar volume curve is not limited to seven types (seven), and any type can be selected from four types and sixteen types in consideration of calculation accuracy, processing speed, and storage capacity. It goes without saying that you can do it. further,
If not a constant molar volume curve, but a constant molar volume straight line,
The coefficients a _i0 and a _i1 are stored.

In the RAM of the storage unit 45,
When performing an operation based on (1), the coefficient a _i0, A_i1, ...
The two sets of registers [Ad] and [Au] for reference are
Each is set corresponding to two constant molar volume curves.
And two constant molar volume curves selected as described below.
Are assigned to the two register groups [Ad] and [Au].
Set (store) each. This gives two constant molar volumes
The product curve is now selected. The operation unit 4
1 is obtained by the calculation program corresponding to the above equation (1).
Corresponds to the detected temperature with reference to the register group [Ad] and [Au]
Calculate the pressure to be applied. And the result of these operations and
Temperature compensation from reference pressure and detected pressure corresponding to each curve
The pressure P20 is calculated. That is, the detected pressure Pt is the temperature
It is converted to the compensation pressure P20.

FIG. 4 shows a method for obtaining the temperature compensation pressure P20 from the detected temperature t and the detected pressure Pt based on two constant molar volume curves selected from a plurality of (seven in this embodiment) constant molar volume curves. FIG. The constant molar volume curve is a function of temperature as in the above equation (1). As shown in the figure, the function of the constant molar volume curve with the higher reference pressure is Fu (t),
The function of the constant molar volume curve with the lower reference pressure is defined as Fd (t).

The pressure corresponding to the detected temperature t on each constant molar volume curve is obtained as Fu (t) and Fd (t), and the pressure corresponding to the reference temperature (20 ° C.) is Fu.
(20) and Fd (20). Fu (20),
The value of Fd (20) is known for each constant molar volume curve and need not be calculated. Fu (t) is defined as a virtual constant molar volume curve F '(t) passing through the intersection of the detected pressure Pt and the detected temperature t.
And Fd (t), the pressure corresponding to the reference temperature (20 ° C.) on the virtual constant molar volume curve F ′ (t) is calculated as the temperature compensation pressure P20 with respect to the detected pressure Pt.
Can be considered.

That is, the temperature compensation pressure P20 is given by the following equation (2).
Can be obtained by proportional distribution.

(Equation 2)

In the example of FIG. 4, the case where the detected pressure Pt is within the range of both pressures at the detected temperature t of the two constant molar volume curves (interpolation) is shown. In the case where the detected pressure Pt is outside the range (in the case of extrapolation), it can be similarly obtained by the above equation (2).

In this embodiment, the two constant molar volume curves Fu (t) and Fd (t) have a reference pressure of 0.80 MPa in the initial state.
a and 0.20 MPa, and the first time, the temperature compensation pressure P20 is determined from this constant molar volume curve. Thereafter, when calculating the temperature compensation pressure P20 for the second and subsequent times,
Two adjacent constant molar volume curves sandwiching the previous temperature compensation pressure P20 are set.

FIGS. 5 to 9 are flowcharts of a control program of the CPU constituting the microcomputer of the control unit 24. FIG. 5 is a flowchart of a main routine, FIG. 7 is a flowchart of an interrupt process, and FIGS. 9 is a flowchart of various subroutines.
Hereinafter, the operation will be described based on the flowchart. In the following description and each flowchart, each register and flag used for control are represented by the following labels, and each register and flag and their storage contents are represented by the same label unless otherwise specified.

A (i): A register of a coefficient table in which a set of coefficients of a constant molar volume curve corresponding to the i-th reference pressure is stored. [Ad]: Reference of two selected constant molar volume curves. Register group for storing coefficient set with lower pressure [Au]: Register group for storing coefficient set with higher reference pressure of two selected constant molar volume curves Pt: Register for detected pressure RB1: Register RB2 that stores the oldest data of the ring buffer that stores the detected pressure RB2: Register that stores the second oldest data of the ring buffer that stores the detected pressure RB3: Register that is the third oldest of the ring buffer that stores the detected pressure Register RB4 in which data is stored RB4: Register in which the fourth oldest data of the ring buffer for storing the detected pressure is stored RB5: Ring bar in which the detected pressure is stored Register the most recent data is stored in the file

P1o: A register for saving the old pressure data for detecting the pressure rise rate every 200 msec p2o: A register for saving the old pressure data for detecting the pressure rise rate every 2 seconds p3o: Every 20 seconds A register for saving the old pressure data for detecting the pressure rise rate p1n: A register for saving the new pressure data for detecting the pressure rise rate every 200 msec p2n: A register for detecting the pressure rise rate every 2 seconds Register for saving new pressure data p3n: Register for saving new pressure data to detect pressure rise rate every 20 seconds t: Register for detected temperature P20: Register for temperature compensation pressure i: Order of constant molar volume curve P20, i: Register of the reference pressure corresponding to the reference temperature in the i-th constant molar volume curve ct20m: Measure 20 msec by 5 msec interrupt processing Ct1: Counter register for measuring 200 msec in 5 msec interrupt processing ct2: Counter register for measuring 2 sec in 5 msec interrupt processing ct3: Counter register for measuring 20 sec in 5 msec interrupt processing S1: A flag indicating that 200 msec has elapsed S2: A flag indicating that 2 seconds have elapsed S3: A flag indicating that 20 seconds have elapsed a: The processing time when calculating the pressure increase rate of 200 msec, 2 sec, and 20 sec is sequentially delayed by 5 msec. Flag to let

When the CPU starts the processing of the main routine of FIG. 5 by turning on the power or the like, first, at step S1, resetting and setting each flag and each register, or starting each part of the pressure state monitoring device 6 is started. Perform initialization processing such as When the initialization process is completed, the insulation amplifier 65 of the analog signal transmission unit 27, based on the original pressure voltage signal output from the pressure detection unit 21,
A pressure transmission signal having a current range of 4 to 20 [mA] is formed by the voltage / current converter 66 and the second transmission signal output unit 67, and the analog transmission is performed via the terminal plate 28 and the first analog signal transmission line 4. Output to the local monitoring device 7. Further, based on the original temperature voltage signal, the insulation amplifier 70 and the voltage / current converter 71 of the analog signal transmission unit 27 are used.
And 3 to 20 [m] by the third transmission signal output unit 72.
A], a temperature transmission signal having a current range of A] is formed, and is output to the analog local monitoring device 7 via the terminal plate 28 and the first analog signal transmission line 4.

As a result, the pressure transmission signal and the temperature transmission signal are transmitted to the analog local monitoring device 7, and the analog local monitoring device 7 mediates these signals to the first central monitoring device. 10 will be transmitted. As a result, the first central monitoring apparatus 10 performs signal processing based on the pressure transmission signal and the temperature transmission signal, and stops power transmission as necessary, or notifies the supervisor. That is, the observer can take preventive maintenance measures. Hereinafter, similarly, the analog local monitoring device 7
The first central monitoring device 10 continues the monitoring operation in parallel with the operation of the digital local monitoring device 8 and the second central monitoring device 12 described later.

When the initialization processing in step S1 is completed,
In step S2, 10 minutes for the 10-minute
A minute timer is started, and in step S3, a 5 ms timer for measuring 5 ms of the clock unit 46 is started to start a timer interrupt. As a result, the CPU performs an interrupt process of FIG. 7 described later by an interrupt signal output from the 5 msec timer every 5 msec.

Next, the CPU determines in step S4 that the ROM
Reference pressure 0.20MP stored in coefficient table
The coefficient set A (1) of the constant molar volume curve a is stored in a register group [Ad
], A coefficient set A (7) of a constant molar volume curve at a reference pressure of 0.80 MPa is set in a register group [Au], and two constant molar volume curves used for calculating a temperature compensation pressure are set on the low pressure side. Select curves near the control limit and near the high pressure side control limit. Furthermore, the selected 2
An initial curve flag indicating that the constant molar volume curve of this book is set as an initial state is set.

Next, in step S5, data of the gas temperature t (detected temperature) is read from the A / D converter 44, and in step S6, it is determined whether or not the gas temperature t is in the range of -20.degree. judge. If the temperature is not within the range of −20 ° C. to 60 ° C., the data of the temperature sensor abnormality is output and displayed in step S7, the high-pressure side alarm output processing is performed, and the interruption of the 5 msec timer is prohibited in step S7 ′, and the standby is performed. (Wait)
I do. Thus, an alarm is issued when the gas temperature is abnormal, the interruption process is interrupted, and the process stands by until a key input or the like is made after restoration. It should be noted that the processing corresponding to the key input after recovery is a forced interrupt processing for returning to the main routine, and a detailed description thereof will be omitted. -20 ° C
If the temperature is within the range of -60 ° C., the temperature compensation pressure calculation process of FIG. 6 is performed in step S8, and the pressure abnormality determination process based on the result of the temperature compensation pressure calculation process and the display of the temperature compensation pressure P20 are performed in step S9. Transmit the temperature compensation pressure transmission signal. Then, in step S10, other processing such as processing corresponding to the operation of the setting unit and display control is performed, and step S10 is performed.
Return to 5. Thus, steps S5 to S10
During the repetition of the above, the interrupt processing of FIG. 7 is performed every 5 msec by the interrupt signal from the 5 msec timer.

In the interrupt processing shown in FIG.
In step 11, the 5 msec timer is restarted for the next interrupt processing. In step S12, data of the gas pressure Pt (detected pressure) is read from the output of the A / D converter 44. In step S13, the power is supplied based on the 10-minute timer. It is determined whether or not 10 minutes have elapsed since the was input. This is a process for preventing erroneous detection of a pressure rise because the state in the pressure vessel of the GIS is likely to be in an unsteady state for 10 minutes after the power is turned on. And 10
If the minutes have not elapsed, in step S14, the gas pressure Pt is set in the registers p1o, p2o, and p3o, respectively, and the routine returns to the original routine. Note that this register p1o,
The data set in p2o and p3o are 200 msec and 2 sec, respectively, immediately before the lapse of 10 minutes when 10 minutes have passed.
The gas pressure before and 20 seconds before is saved, and is used only for the first time as old data at the time of detecting the pressure rise rate described later.

If 10 minutes have elapsed in step S13, the gas pressure Pt is reduced to -0.101MP in step S15.
a to determine whether it is within the range of 1.000 MPa,
If it is out of the range, the data of the pressure sensor abnormality is output and displayed in step S16, a high-pressure side alarm output process is performed, and in step S16 ', the interruption of the 5 msec timer is prohibited and the operation waits. Thus, when the gas pressure is abnormal, an alarm is issued, the interruption process is interrupted, and the process stands by until a key input or the like after restoration is made. It should be noted that the processing corresponding to the key input after recovery is a forced interrupt processing for returning to the main routine, and a detailed description thereof will be omitted.

If the gas pressure Pt is within the range in step S15, the gas pressure Pt is written in the ring buffer in step S17, and the flow advances to step S18. The ring buffer is provided with at least five registers for writing the gas pressure Pt, and updates the write pointer for each write operation to write time-series data. In this description, RB1 indicates the oldest data, RB2 indicates the second oldest data, RB3 indicates the third oldest data, RB4 indicates the fourth oldest data, and RB5 indicates the latest data.

Next, in step S18, "ct20m =
It is determined whether or not "3", that is, whether or not the value of the counter register ct20m is "3". If "ct20m = 3", ct20m is incremented by "1" in step S19, and the process proceeds to step S103. If "ct20m = 3", the pressure rise rate detection processing (I) of FIG. 8 is performed in step S101, and ct20m is reset in step S102, and the process proceeds to step S103. That is, the counter register ct20m is reset to “0” by the initial setting, and step S18
Is determined, the increment process in step S19, and the reset process in step S102 are performed.
01, the processing in step S102 is 20 msec (5 msec
× 4). And step S
At 103, a pressure rise rate detection process (II) of FIG.
To return to the original routine. That is, step S103 is performed every 5 msec, and 200 msec is received in response to the result of the pressure rise rate detection processing (I) in step S101.
The calculation and determination of the pressure increase rate every 2 seconds and every 20 seconds are executed with a delay of 5 msec. By repeating the above interrupt processing every 5 msec, the gas pressure is sampled at a sampling cycle of 5 msec.

In the pressure rise rate detection processing (I) of FIG. 8, the detected pressures RB1, RB of the ring buffer are determined in step S21.
Calculate the pressure rise rate from 2, RB3, RB4, RB5,
A determination process for detecting an instantaneous abnormal rise is performed based on the calculation result, and an alarm output process is performed based on the determination result. Then, the counter register ct1 for counting 200 msec is incremented by "1" and the operation proceeds to step S22. The calculation of the pressure rise rate is performed, for example, by calculating the minimum value and the maximum value of the five detected pressures RB1, RB2, RB3, RB4, and RB5, and determining the sampling time difference (5 msec or 10 msec or 15 msec or It may be obtained by dividing the difference between the maximum value and the minimum value in 20 msec). The determination process is performed by comparison with a predetermined reference pressure increase rate. Step S21
, The register RB1 is the oldest data and the register RB5 is the latest data. Needless to say, in the timing example of FIG. 10 described later, the data of the register RB5 is sequentially written in the ring buffer in a time series every 5 msec, and is stored in the register RB1 in the next calculation of step S21, and is stored in the register RB5.
Stores the latest data at the time when 20 msec has elapsed.

As described above, at step S21, 20 m
The operation of detecting an instantaneous abnormal rise every second is performed. From the next step S22, a sudden abnormal rise every 200msec, a slow abnormal rise every 2sec, and a very slow abnormal rise every 20sec are detected. To do
Using the counter registers ct1, ct2, ct3, the timing is controlled so as to correspond to each time interval, and each detected pressure is taken in.

That is, in step S22, "ct1 =
10 ”(if the value of the counter register ct1 is“ 1 ”
0 "), and returns to the original routine (interrupt processing) unless" ct1 = 10 ". On the other hand, "ct
If "1 = 10", ct1 is reset in step S23, a flag S1 indicating that 200 msec has elapsed is set, a detected pressure RB5 is set in a register p1n, and a counter register ct2 for measuring 2 seconds is set to "1". The value is incremented by 1 "and the process proceeds to step S24. That is, the counter register ct1 is reset to "0" by default, and every time 20 msec elapses, step S2 is executed.
Since it is incremented by 1, the processing in step S23 is performed for 200 msec (20 mse
c × 10).

In step S24, it is determined whether or not "ct2 = 10". If "ct2 = 10", the process returns to the original routine. If "ct2 = 10", the process returns to step S2.
Go to 5. In step S25, ct2 is reset, a flag S2 indicating that 2 seconds have elapsed is set, a detected pressure RB5 is set in a register p2n, and a counter register ct3 for measuring 20 seconds is incremented by "1", and step S26 is performed. Proceed to. That is, the counter register ct2 is reset to "0" by default, and is incremented in step S23 every 200 msec. Therefore, the processing in step S25 is performed for 2 sec (200 msec × 10) by the determination in step S24.
It is executed every time.

In step S26, it is determined whether or not "ct3 = 10". If "ct3 = 10", the process returns to the original routine. If "ct3 = 10", step S2 is executed.
Go to 7. In step S27, ct3 is reset, a flag S3 indicating that 20 seconds have elapsed is set, the detected pressure RB5 is set in the register p3n, and the routine returns to the original routine. That is, the counter register ct3 is reset to “0” by the initial setting, and 2se
Each time c elapses, the value is incremented in step S25, so that the process in step S27 is executed every 20 seconds (2 sec × 10) based on the determination in step S26.

The pressure rise rate detection process (II) in FIG. 9 detects a sudden abnormal rise every 200 msec from the detected pressure RB5 set in the registers p1n, p2n, p3n in the pressure rise rate detection process (I). Pressure rise rate (hereinafter “20
0 msec width pressure rise rate. " ) Pressure rise rate for detecting a slow abnormal rise every 2 seconds (hereafter,
It is called "2sec width pressure rise rate". ), A process of calculating a pressure rise rate (hereinafter, referred to as “20-sec width pressure rise rate”) for detecting a very slow abnormal rise every 20 seconds.

Here, 200 msec, 2 sec, 20 sec
Since the count for measuring the time is based on the same 5 msec interrupt processing, the pressure rise rate detection processing (I) (FIG. 8)
In steps S23, S25, and S
27 are the same interrupt timing (5 msec,
(A timing of a common multiple of 200 msec, 2 sec, and 20 sec). At this time, the register p1
When each pressure increase rate is calculated when the detected pressure RB5 is set to n, p2n, and p3n, 20 msec in step S21
200msec width pressure rise rate in addition to each pressure rise rate, 2se
c Width pressure increase rate, 20 sec At most, four types of calculations of the width pressure increase rate are performed at the same interrupt timing, and one interrupt process requires time and effort.

Therefore, in the pressure rise rate detection processing (II), 5
The timing of calculating the four types of pressure rise rates is shifted by 5 msec so that at most one type of pressure rise rate is calculated in one interrupt processing of msec. First, in step S31, a flag S1 indicating a timing of 200 msec is set.
It is determined whether or not is set. If it has not been set, the process proceeds to step S34, and if it has been set, it is determined in step S32 whether or not "a = 1". Here, the flag a is reset to "0" by default, and is set to "1" in step S301 of this flow every time 5 msec is passed once, and is set to "1". Steps S33, S36, and S39 are performed.

If not "a = 1", step S301
To set the flag a to "1" and return to the original routine. If “a = 1”, a 200 msec width pressure rise rate is calculated from the new and old detected pressures p1n and p1o in step S33, and a determination process for detecting a sudden abnormal rise is performed based on the calculation result. The alarm output process is performed.
Further, for the next calculation, the latest detected pressure p1n is stored in p1o as the old detected pressure, and the flag S1 is reset. Then, the flag a is reset to "0" in order to pass the process of 2 sec, and the process proceeds to step S34.

Although a detailed description of each step will be omitted below, as can be seen from the flowchart, steps S34 to S36 perform processing such as calculation of a 2-sec width pressure increase rate, and steps S37 to S37.
Reference numeral 39 denotes processing such as calculation of a 20-sec width pressure increase rate under the same control as calculation of a 200-msec pressure increase rate.

When the above processing has reached the timing of, for example, 20 sec, the timings of 20 msec, 200 msec and 2 sec have been reached.
In the interrupt processing at this time, the process returns to the original routine from step S32 to step S301 in FIG. 9, and the processing of 200 msec, 2 sec and 20 sec is passed. Next interrupt processing (Figure 7)
Then, step S18 → step S19 → step S1
03, step S31 in FIG. 9 → step S32 →
Step S33 → step S34 → step S35 → step S301, and the process returns to the original routine.
Only the processing of msec is performed. Similarly, in the next interrupt processing, only the processing for 2 seconds is performed, and in the next interrupt processing, only the processing for 20 seconds is performed.

FIG. 10 is a diagram showing an example of the timing of the processing of each of the above-mentioned pressure rise rates. The detected pressures RB1, RB2, RB3, RB4, RB5 sampled every 5 msec.
Thus, at time t0, the arithmetic processing A of 20 msec is performed, and after the next 5 msec, the arithmetic processing B of 200 msec is performed from p1o and p1n. After the next 5 msec, p2
Calculation processing C of 2 sec is performed from o and p2n, and the next 5
After m sec, the arithmetic processing D of 20 sec from p3o, p3n is performed. As described above, since the processing is shifted by 5 msec, one interrupt processing can be completed in a short time. In other words, you can perform other functions with plenty of time,
The reliability of each function increases.

Next, the temperature compensation pressure calculation processing of FIG. 6 will be described. First, in step S41, the A / D converter 44
The data of the gas pressure Pt is read from the output of step S42, and in step S42, Fd (t), Fd (t), from the selected two constant molar volume curves and the detected temperature t read in step S5 (FIG. 5).
Fu (t) is calculated and the reference pressure Fd (2
0) and Fu (20) are calculated. Next, in step S43, from the gas pressures Pt, Fd (t), Fu (t), Fd (20) and Fu (20),
The temperature compensation pressure P20 corresponding to the gas pressure Pt is calculated based on the above equation (2).

Next, in step S44, it is determined whether or not the initial curve flag has been reset. If the initial curve flag has not been reset, the first process is performed.
I which satisfies P20, i ≦ P20 ≦ P20, i + 1, that is, the smaller number i of the two constant molar volume curves having the reference pressure sandwiching the temperature compensation pressure P20 of the calculation result is obtained, and in step S46 the initial curve is obtained. The flag is reset and the process proceeds to step S401. Thus, the number of the constant molar volume curve used in the next calculation is obtained.

If the initial curve flag has been reset in step S44, the process is the second or subsequent process. Therefore, in step S47, it is determined whether or not “Fd (20) ≦ P20 ≦ Fu (20)”, that is, calculation is performed. It is determined whether or not the resulting temperature compensation pressure P20 is within the range of the reference pressures of the two currently selected constant molar volume curves, and if it is within the range, there is no need to update the constant molar volume curve. Return to the original routine. On the other hand, if it is out of the range, “0.
20MPa ≦ P20 ≦ 0.80MPa ”, that is, whether the calculated temperature compensation pressure P20 is in the vicinity of the low-pressure control limit and in the vicinity of the high-pressure control limit. If it is outside the range, there are no two constant molar volume curves sandwiching the temperature compensation pressure P20, so the first calculation of the temperature compensation pressure P20 at startup is performed again. That is, in step S49, as in step S4 of the main routine, the coefficient set A (1) of the constant molar volume curve at the reference pressure of 0.20 MPa stored in the coefficient table of the ROM is set in the register group [Ad]. , Reference pressure 0.8
A set of coefficients A (7) of a constant molar volume curve of 0 MPa is set in a register group [Au], and two constant molar volume curves used for calculating the temperature compensation pressure are set near the low pressure side control limit and the high pressure side control limit. Select a nearby curve. Further, an initial curve flag indicating that the two constant molar volume curves thus selected are set as the initial state is set,
Return to the original routine.

On the other hand, if the temperature compensation pressure P20 is in the range between the vicinity of the low-pressure control limit and the vicinity of the high-pressure control limit, the flow proceeds to step S45, then to step S46, and further to step S401. Step S45 and Step S
The processing with 46 is performed as described above. In step S401, the coefficient set A (i) in the coefficient table is set in the register group [Ad], and the coefficient set A (i + 1) is set.
Is set in the register group [Au], and the process returns to the original routine. As a result, two adjacent constant molar volume curves sandwiching the temperature compensation pressure P20 of the detection result are selected.

In step S45, P20, i ≦ P20 ≦
When i to be P20, i + 1 is obtained, it can be obtained by comparing P20 with each reference pressure of each constant molar volume curve. For example, when processing as shown in FIG. The comparison with the reference pressure need not be performed. In FIG. 11, the same steps as those in FIG. 6 are denoted by the same reference numerals.
In the processing of FIG. 11, step S is performed in the second and subsequent processing.
In step S47 ', it is determined whether the temperature compensation pressure P20 is out of the range of the reference pressures of the two currently selected constant molar volume curves on the lower pressure side. In step S47 ", i is decremented. If it is not off to the low pressure side, in step S48 ',
It is determined whether the temperature compensation pressure P20 is out of the range of the reference pressures of the two currently selected constant molar volume curves on the high pressure side, and if not, i is incremented in step S48 ". Two constant molar volume curves can be selected in step S401, and if it is off to the low pressure side in step S47 'or if it is off to the high pressure side in step S48', Proceed to S48, where "0.20 MP
It is determined whether or not a ≦ P20 ≦ 0.80 MPa ”, that is, whether or not the calculated temperature compensation pressure P20 is within the range near the low-pressure control limit and the range near the high-pressure control limit.
If it is within the range, the process returns to the original routine. If the temperature compensation pressure is outside the range, there are no two constant molar volume curves sandwiching the temperature compensation pressure P20.
Repeat 20 calculations. That is, in step S49, the same processing as in step S4 of the main routine is performed, and the process returns to the original routine. In the normal case, when the temperature compensation pressure P20 is out of the range, it is at most more than one constant molar volume curve. Therefore, the two constant molar volume curves selected in such a process are also equal to the temperature compensating pressure P20. P20 is sandwiched. The processing in step S41 in FIGS. 6 and 11 may be omitted because the latest detected pressure data is stored in the register RB5 in step S12 in FIG. This eliminates the time required for the A / D conversion processing, and shortens the processing time. The processing of steps S48 and S49 in FIGS. 6 and 11 is processing for the calculation error of the temperature compensation pressure P20, the abnormality of the temperature sensor, and the abnormality of the pressure sensor, and is performed in steps S6, S7, and FIG. This is a process to supplement the processes of steps S15 and S16.

FIG. 12 is a view for explaining an embodiment using a constant molar volume curve approximated by a polygonal line. In this embodiment, the range of the lower limit temperature td and the upper limit temperature tu of the detected temperature is divided into a plurality of sections j.
(J = 1, 2,...). Then, similarly to the above embodiment, a polygonal line approximation curve in which each section is approximated by a straight line is used for each of a plurality of constant molar volume curves distinguished by the number i (i = 1, 2,..., 7). Note that a straight line in an arbitrary section j in an arbitrary constant molar volume curve i is represented by FLi, j. Then, as shown in FIG. 13, the data of the slope αi, j and intercept βi, j of each straight line FLi, j in the temperature-pressure coordinate system is stored in the ROM in association with each section number j. .
Further, as shown in FIG. 13, the lower limit of the temperature of each section (td = t ₁₎ and the upper limit value (tu = t _{j + 1)} of data also section number j (j = 1,2, ..., m ,..., J + 1) are stored in the ROM.

With the above configuration, the temperature compensation pressure P20 is obtained as follows. 2 selected as in the previous embodiment
From each of the constant molar volume curves, two straight lines are detected, each of which is a linear approximation of the two constant molar volume curves corresponding to the section including the detected temperature t. Straight line of detected temperature t and 2
The pressure at each intersection of each of two straight lines obtained by approximating the two constant molar volume curves is determined, and this pressure is determined as the pressure Fu (t), Fd (t) corresponding to the detected temperature t in the two constant molar volume curves. )
Consider Similarly, from each of the two constant molar volume curves, two straight lines each obtained by linearly approximating the two constant molar volume curves corresponding to the section including 20 ° C. are detected,
The pressure at the intersection of each of two straight lines obtained by approximating the two constant molar volume curves with a straight line at 20 ° C. is determined, and this pressure is used as the reference pressure Fu (20), Fd in the two constant molar volume curves.
(20) Then, the detected pressure Pt and the above Fu
From (t), Fd (t), Fu (20) and Fd (20), the temperature compensation pressure P20 is obtained by proportional distribution using the above-mentioned equation (2).

According to this embodiment, when obtaining each pressure, it is only necessary to obtain the intersection of the straight lines, so that the calculation is simplified and the processing is performed quickly.

In the above embodiment, the GIL (gas insulated
The case of monitoring the pressure state of gas in the pipe of electric wire)
However, the present invention is not limited to this, and the gas-insulated switchgear
(GIS), monitoring the gas pressure state of gas-insulated transformer
Needless to say, the present invention can be applied to such cases. In addition,
Sulfur hexafluoride gas (SF₆gas)
As described in the case of
Mixed gas "," SF ₆Alternative gas ", other gases
It goes without saying that it can be applied.

[0088]

As described above, according to the first aspect of the present invention,
According to the pressure monitoring device for gas for electrical insulation described in the above, 2
At the time of calculating the temperature compensating pressure for the second and subsequent times, the adjacent 2 sandwiching the value of the temperature compensating pressure obtained as a result of the previous temperature compensating pressure calculation
Since the constant molar volume curve is selected, when there is little change in the temperature compensation pressure, in most cases, the same two constant molar volume curves are used as in the previous time. Processing time is shortened. In addition, even when the constant molar volume curve is selected again, in most cases, it is sufficient to select the previous two constant molar volume curves.
Processing time is reduced.

According to the pressure monitoring apparatus of the second aspect of the present invention, in addition to the function and effect of the first aspect, the first temperature compensation pressure is calculated by two constant pressure Since the calculation is performed by interpolation between the volume curves, almost average accuracy is obtained as the first calculation result.

According to the pressure monitoring apparatus of the third aspect of the present invention, in addition to the effects of the first and second aspects, the constant molar volume curve is approximated by a broken line. Therefore, a linear equation may be used for calculating the temperature compensation pressure, and the processing time is further reduced.

According to the pressure monitoring apparatus for an electrically insulating gas according to a fourth aspect of the present invention, in addition to the effects of the first or second aspect, when a constant molar volume curve is selected, its coefficient is selected. Need only be read from the storage means.

According to the pressure monitoring apparatus for an electrically insulating gas according to the fifth aspect of the present invention, in addition to the effect of the third aspect, when a straight line approximating a broken line of a constant molar volume curve is selected, It is only necessary to read out the coefficients from the storage means.

According to a pressure state monitoring apparatus for an electrically insulating gas according to a sixth aspect of the present invention, in addition to the effects of the first, second, third, fourth or fifth aspects, Therefore, the present invention can be applied to a general electric insulating gas or a mixture of a plurality of electric insulating gases.

According to the pressure monitoring apparatus for an electrically insulating gas according to a seventh aspect of the present invention, in addition to the functions and effects of the first, second, third, fourth or fifth aspects, Therefore, it can be applied to the case of SF ₆ gas having excellent electrical insulation.

Further, according to the pressure state monitoring device for an electrically insulating gas according to the eighth aspect of the present invention, each pressure at the detected temperature of the first constant molar volume curve and the second constant molar volume curve is determined. When calculating the temperature compensation pressure by interpolation or extrapolation from the detected pressure, the calculation is performed by proportional distribution, so that the calculation is simplified.

According to the pressure monitoring apparatus for an electrically insulating gas according to the ninth aspect of the present invention, in addition to the operation and effect of the eighth aspect, even when the temperature compensation pressure is calculated by extrapolation, the first compensation can be performed. , Or a second constant molar volume curve, so that a highly accurate calculation result can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an SF ₆ gas pressure state monitoring system according to an embodiment of the present invention.

FIG. 2 is a schematic configuration block diagram of a pressure state monitoring device according to an embodiment of the present invention.

FIG. 3 is a diagram conceptually showing a coefficient table of an embodiment in which coefficients of a constant molar volume curve of the present invention are stored.

FIG. 4 is a diagram illustrating a method for obtaining a temperature compensation pressure from a detected temperature and a detected pressure based on two constant molar volume curves in the embodiment of the present invention.

FIG. 5 is a flowchart of a main routine in the embodiment of the present invention.

FIG. 6 is a flowchart of a temperature compensation pressure calculation process according to the embodiment of the present invention.

FIG. 7 is a flowchart of an interrupt process according to the embodiment of the present invention.

FIG. 8 is a pressure rise rate detection process according to the embodiment of the present invention.
It is a flowchart of (I).

FIG. 9 is a pressure rise rate detection process in the embodiment of the present invention.
It is a flowchart of (II).

FIG. 10 is a diagram illustrating an example of a timing of processing of a pressure increase rate according to the embodiment of the present invention.

FIG. 11 is a flowchart illustrating another example of the temperature compensation pressure calculation process according to the embodiment of the present invention.

FIG. 12 is a diagram illustrating an embodiment of the present invention using a constant molar volume curve approximated by a polygonal line.

FIG. 13 is a diagram conceptually showing a table in which data of the temperature of each section and the slope and intercept of each straight line in the embodiment using the constant molar volume curve approximated by the broken line of the present invention.

[Explanation of symbols]

Reference Signs List 1 SF ₆ gas pressure state monitoring system 2C pressure vessel 3 pressure introduction pipe 6 pressure state monitoring device 21 pressure detection unit 22 temperature detection unit 24 control unit 40 control unit 41 arithmetic unit 42 comparison unit 43 judgment unit 44 A / D converter 45 storage unit

Claims (9)

[Claims] 1. A temperature compensation pressure, which is a pressure at a predetermined reference temperature, is calculated based on a detected pressure and a detected temperature of an electric insulating gas sealed in a pressure vessel, and the electric insulation is calculated based on the temperature compensated pressure. A pressure state monitoring device for monitoring the pressure of the working gas, wherein a plurality of molar volumes corresponding to a plurality of pressures ranging from a vicinity of a high-pressure control limit to a vicinity of a low-pressure control limit of the electrical insulating gas are provided. Using a plurality of constant molar volume curves, temperature data corresponding to the detected temperature, pressure data corresponding to the detected pressure, and the temperature compensating pressure from two constant molar volume curves of the plurality of constant molar volume curves. Using a preset constant molar volume curve as two constant molar volume curves used for calculating the first temperature compensation pressure at the time of starting the pressure state monitoring device, As the two constant molar volume curves used for the second and subsequent temperature compensation pressure calculations, two adjacent constant molar volume curves sandwiching the temperature compensation pressure value obtained as a result of the previous temperature compensation pressure calculation are selected. A pressure state monitoring device for an electrically insulating gas, characterized in that the pressure state is monitored. 2. Two predetermined constant molar volume curves used for the first temperature compensation pressure calculation are a curve near the high pressure side control limit and a curve near the low pressure side control limit. The pressure monitoring device for an electrically insulating gas according to claim 1, wherein: 3. The constant molar volume curve is divided into a plurality of sections within a range between a lower detection temperature limit and a higher detection temperature limit of the detection temperature, and the constant molar volume curve in each section is regarded as a straight line. 3. The pressure state monitoring device according to claim 1, wherein the temperature compensation pressure is calculated by performing a proportional distribution operation based on the broken line approximation line. 4. The method according to claim 1, wherein the calculation of the temperature compensation pressure is performed by a microcomputer, and a coefficient of the constant molar volume curve is stored in a storage means of the microcomputer. Pressure monitoring device for gas for electrical insulation. 5. The microcomputer according to claim 3, wherein said temperature compensation pressure is calculated by a microcomputer, and a coefficient of a straight line approximation of said constant molar volume curve is stored in a storage means of said microcomputer. Pressure monitoring device for electrical insulation gas. 6. A method according to claim 1, wherein said constant molar volume curve is obtained in advance by solving using a virial type equation of state. 6. The pressure monitoring device for an electrical insulating gas according to claim 5. 7. The constant molar volume curve is previously determined by Beatti.
6. The pressure monitoring of the gas for electrical insulation according to claim 1, wherein the pressure is monitored by solving using an e-Bridgeman's equation. apparatus. 8. A temperature compensation pressure, which is a pressure at a predetermined reference temperature, is calculated based on a detected pressure and a detected temperature of the electric insulating gas sealed in the pressure vessel, and based on the temperature compensated pressure, the electric insulation is calculated. A pressure monitoring device for monitoring the pressure of the gas for use in electrical insulation, comprising: a first constant molar volume curve for different molar volumes corresponding to a first pressure and a second pressure of the gas for electrical insulation; 2 using two constant molar volume curves, from the temperature data corresponding to the detected temperature, the pressure data corresponding to the detected pressure, the first constant molar volume curve, and the second constant molar volume curve, An apparatus for monitoring the pressure state of an electrically insulating gas, wherein the temperature compensation pressure is calculated by proportional distribution. 9. The range of the detected pressure for calculating the temperature compensation pressure is determined based on a pressure value near a first pressure on the first constant molar volume curve intersecting a straight line of the detected temperature. 9. The pressure monitoring apparatus for an electrically insulating gas according to claim 8, wherein the pressure is in a range of a pressure value near a second pressure on the second constant molar volume curve crossing a temperature line.