CN110929417A - Temperature early warning control method and device based on fireproof power capacitor thermal stability calculation - Google Patents
Temperature early warning control method and device based on fireproof power capacitor thermal stability calculation Download PDFInfo
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Abstract
本发明公开了一种基于防火电力电容器热稳定计算的温度预警控制方法及装置，所述方法包括：获取所述防火电力电容器的产品信息，根据所述防火电力电容器的产品信息以及预设模型，计算所述防火电力电容器的损耗功率、建立热传导过程模型、外壳散热功率模型以及热平衡模型，计算所述防火电力电容器的内部最热点温度、内层壳体温度以及外壳温度；并根据预设预警阈值，对所述防火电力电容器温度进行预警控制；所述方法在获取所述防火电力电容器的基本产品信息后，就可以计算出所述产品的内部最热点温度、内层壳体温度和外壳温度，高效便捷、准确性高，有效地解决了防火电力电容器热稳定温度预警控制问题。
The invention discloses a temperature early warning control method and device based on thermal stability calculation of a fireproof power capacitor. The method includes: acquiring product information of the fireproof power capacitor, and according to the product information of the fireproof power capacitor and a preset model, Calculate the power loss of the fireproof power capacitor, establish a heat conduction process model, a shell heat dissipation power model and a heat balance model, and calculate the internal hottest point temperature, inner shell temperature and shell temperature of the fireproof power capacitor; and according to preset warning thresholds , to perform early warning control on the temperature of the fireproof power capacitor; after the method obtains the basic product information of the fireproof power capacitor, it can calculate the internal hottest point temperature, the inner shell temperature and the shell temperature of the product, It is efficient, convenient and accurate, and effectively solves the problem of early warning control of thermal stability and temperature of fireproof power capacitors.
Description
Technical Field
The invention relates to the field of thermal stability analysis of a fireproof power capacitor, in particular to a temperature early warning control method and device based on thermal stability calculation of the fireproof power capacitor.
Background
Indoor and underground substations have been rapidly developed in power grids in order to reduce costs and save land resources. The parallel capacitor is one of main equipment of a transformer substation, if a fault occurs in the conventional parallel capacitor used at present, the internal temperature is too high, the pressure is increased, the shell of the capacitor is broken, insulating oil is leaked, and once the fire occurs, the insulating oil is burnt in advance, so that a fire accident is caused. Indoor and underground transformer stations have poor heat dissipation conditions and small space, so that the condition is more dangerous. In order to solve the fire-proof problem of the traditional parallel capacitor, a fire-proof power capacitor appears in the power industry. The fireproof power capacitor is formed by adding a layer of shell on the basis of the traditional parallel capacitor unit shell and filling a water-based fireproof medium between the two layers of shells, so that the fireproof requirement of the capacitor is met.
The parallel capacitor is used as important equipment for normal operation of a power grid, and plays a key role in reactive compensation, improvement of power quality and the like. Its characteristics are that voltage is high, power is big, the frequency is low, causes its volume great, but because the heat radiating area is little, heat dispersion is relatively poor. Operating experience shows that the failure rate of the capacitor is obviously higher in 6-9 months per year than in other months, which shows that the temperature has a remarkable influence on the operating reliability of the capacitor. Because the temperature of the fireproof power capacitor under the thermal stability is not easy to calculate, early warning control on the temperature of the fireproof power capacitor cannot be timely carried out, the temperature of the medium inside the fireproof power capacitor is too high, the medium material is aged, and the service life and the safe operation of the fireproof power capacitor are influenced.
Disclosure of Invention
In order to solve the problems that the temperature of a fireproof power capacitor under thermal stability is difficult to calculate in the prior art, so that early warning control cannot be timely carried out on the temperature of the fireproof power capacitor, the temperature of a medium in the fireproof power capacitor is too high, the aging of a medium material is caused, and the service life and the safe operation of the fireproof power capacitor are influenced, the invention provides a temperature early warning control method based on the thermal stability calculation of the fireproof power capacitor, which is characterized by comprising the following steps of:
acquiring product information of the fireproof power capacitor, wherein the product information comprises rated voltage, rated frequency, capacitance and loss tangent of the fireproof power capacitor;
calculating the loss power of the fireproof power capacitor in the thermal stability according to the voltage, the rated frequency, the capacitance and the loss tangent of the fireproof power capacitor in the thermal stability;
establishing a heat conduction process model, a shell heat dissipation power model and a heat balance model according to the product information of the fireproof power capacitor and a preset model;
calculating the temperature of the internal hottest point, the temperature of an inner shell and the temperature of an outer shell of the fireproof power capacitor according to the product information of the fireproof power capacitor, the loss power of the fireproof power capacitor during thermal stability, the heat conduction process model, the outer shell heat dissipation power model and the heat balance model;
and carrying out early warning control on the temperature of the fireproof power capacitor according to the temperature of the hottest point in the fireproof power capacitor, the temperature of the inner shell, the temperature of the outer shell and a preset early warning threshold value.
Further, the formula for calculating the power loss of the fireproof power capacitor in thermal equilibrium is as follows:
P＝Qtanδ＝ωCU2tanδ
wherein P is a loss power of the fireproof power capacitor at thermal equilibrium, Q is an output capacity of the fireproof power capacitor, U is a voltage of the fireproof power capacitor at thermal stability, ω is a rated frequency of the fireproof power capacitor, C is the fireproof power capacitor capacitance, and tan δ is a loss tangent of the fireproof power capacitor.
Further, the establishing a heat conduction process model according to the product information of the fireproof power capacitor and a preset model comprises:
conducting heat generated by internal power losses of the fireproof power capacitor to an inner shell of the fireproof power capacitor and conducting the heat from the inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor;
the temperature distribution curve of the heat generated by the internal power loss of the fireproof power capacitor conducted to the inner shell of the fireproof power capacitor and the heat conducted from the inner shell of the fireproof power capacitor to the outer shell of the fireproof power capacitor is regarded as a linearization.
Further, the formula for establishing the heat conduction process model in the preset model is as follows:
Qf＝λ1(tX-tN)A+λ2(tN-tW)A
wherein Q isfIs the heat generation per unit time, lambda, of the fireproof power capacitor1The thermal conductivity from the internal medium of the fireproof power capacitor to the inner shell of the fireproof power capacitor; t is tXThe temperature of the hottest point of the fireproof power capacitor medium is obtained; t is tNThe temperature of the hottest point of the inner shell of the fireproof power capacitor is obtained; lambda [ alpha ]2A thermal conductivity from an inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor; t is tWIs the hottest point temperature of the housing of the fireproof power capacitor, A is the effective heat dissipation of the housing of the fireproof power capacitorArea.
Further, the formula for establishing the shell heat dissipation power model in the preset model is as follows:
Qs＝Qcon+Qrad
wherein Q issIs the heat dissipation per unit time, Q, of the housing of the fireproof power capacitor to the surroundingsconIs the natural convection heat dissipation per unit time of the housing of the fireproof power capacitor to the surrounding environment, QconIs the radiant heat per unit time of the housing of the fireproof power capacitor to the surrounding environment.
Furthermore, the shell of the fireproof power capacitor naturally convects heat quantity Q to the surrounding environment in unit timeconThe formula of (1) is:
Qcon＝α(tW-t0)A
wherein α is the natural convection coefficient of the shell, t0Is the ambient temperature, tWThe temperature of the hottest point of the shell of the fireproof power capacitor is A, and the effective heat dissipation area of the shell of the fireproof power capacitor is A;
the formula of the radiation heat dissipation per unit time qad of the housing of the fireproof power capacitor to the surroundings is,
Qrad＝5.7ε(tW-t0)4A
wherein epsilon is the shell emissivity.
Further, the formula of the natural convection heat dissipation coefficient of the housing is as follows:
α＝1.5(tW-t0)0.35
further, the formula for establishing the thermal equilibrium model in the preset model is as follows:
Pdt＝C`M·d(Δθ)+Qsdt
wherein P is the power loss of the fireproof power capacitor, t is the time, C' is the specific heat capacity of the fireproof power capacitor, M is the mass of the fireproof power capacitor, Delta theta is the temperature rise of the medium of the fireproof power capacitor, and QsFor the fire-proof power capacitor case to the surrounding environmentThe heat dissipation per unit time.
The temperature early warning control device based on fireproof power capacitor thermal stability calculation comprises:
one end of the acquisition unit is respectively connected with the loss power calculation unit, the model establishment unit and the temperature calculation unit; the acquisition unit is used for acquiring product information of the fireproof power capacitor, and rated voltage, rated frequency, capacitance and loss tangent of the fireproof power capacitor;
the device comprises an acquisition unit, a loss power calculation unit and a temperature calculation unit, wherein one end of the acquisition unit is connected with the temperature calculation unit; the loss power calculation unit is used for receiving the product information sent by the acquisition unit, calculating the loss power of the fireproof power capacitor according to the voltage, the rated frequency, the capacitance and the loss tangent of the fireproof power capacitor when the fireproof power capacitor is thermally stable, and sending the loss power of the fireproof power capacitor to the temperature calculation unit;
the model building unit is connected with the acquisition unit at one end and connected with the temperature calculation unit at the other end; the model establishing unit is used for receiving the product information of the fireproof power capacitor, establishing a heat conduction process model, a shell heat dissipation power model and a heat balance model according to the product information of the fireproof power capacitor and a preset model, and transmitting the heat conduction process model, the shell heat dissipation power model and the heat balance model to the temperature calculating unit;
one end of the temperature calculation unit is respectively connected with the acquisition unit, the loss power calculation unit and the model establishment unit, and the other end of the temperature calculation unit is connected with the early warning control unit; the temperature calculation unit is used for calculating the internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor according to the product information of the fireproof power capacitor, the loss power of the fireproof power capacitor, the heat conduction process model, the shell heat dissipation power model and the heat balance model, and sending the internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor to the early warning control unit;
the early warning control unit, one end of the said early warning control unit links with said temperature computational element; the early warning control unit is used for receiving the temperature calculation unit and sending the inside hottest point temperature, the inner shell body temperature and the shell temperature of the fireproof power capacitor, and carrying out early warning control on the temperature of the fireproof power capacitor according to the inside hottest point temperature, the inner shell body temperature, the shell temperature and a preset early warning threshold value of the fireproof power capacitor.
Further, the model establishing unit includes:
a heat conduction process model module, one end of which is connected with the acquisition unit and the other end of which is connected with the temperature calculation unit; the heat conduction process model module is used for establishing a heat conduction process model and sending the heat conduction process model to the temperature calculation unit;
one end of the shell heat dissipation power model module is connected with the acquisition unit, and the other end of the shell heat dissipation power model module is connected with the temperature calculation unit; the shell heat dissipation power model module is used for establishing a shell heat dissipation power model and sending the shell heat dissipation power model to the temperature calculation unit;
one end of the thermal balance model module is connected with the acquisition unit, and the other end of the thermal balance model module is connected with the temperature calculation unit; the thermal balance model module is used for establishing a thermal balance model and sending the thermal balance model to the temperature calculation unit.
Further, the heat conduction process model module for establishing a heat conduction process model includes:
conducting heat generated by internal power losses of the fireproof power capacitor to an inner shell of the fireproof power capacitor and conducting the heat from the inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor;
the temperature distribution curve of the heat generated by the internal power loss of the fireproof power capacitor conducted to the inner shell of the fireproof power capacitor and the heat conducted from the inner shell of the fireproof power capacitor to the outer shell of the fireproof power capacitor is regarded as a linearization.
The invention has the beneficial effects that: according to the technical scheme, the invention provides a temperature early warning control method and device based on fireproof power capacitor thermal stability calculation, wherein the method calculates the temperature of the hottest point in the fireproof power capacitor, the temperature of an inner shell and the temperature of an outer shell according to product information of the fireproof power capacitor and a preset model; according to a preset early warning threshold value, early warning control is carried out on the temperature of the fireproof power capacitor; high efficiency, convenience and high accuracy, and effectively solves the problem of early warning and controlling the thermal stability and the temperature of the fireproof power capacitor.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of a temperature early warning control method based on thermal stability calculation of a fireproof power capacitor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the internal structure of the fireproof power capacitor;
FIG. 3 is a flow chart of a BAMY12/2-500-1 WFH-based fire-protection power capacitor temperature early warning method according to an embodiment of the present invention;
fig. 4 is a structural diagram of a temperature early warning control device based on thermal stability calculation of a fireproof power capacitor according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a temperature early warning control method based on thermal stability calculation of a fireproof power capacitor according to an embodiment of the present invention. Fig. 2 is a schematic diagram of the internal structure of the fireproof power capacitor. As shown in fig. 1 and fig. 2, the method includes:
specifically, according to DL/T1647-2016, the voltage should be 1.2 times of the rated voltage of the product during thermal stability; because the fireproof power capacitor does not change the internal element material and structure of the traditional parallel capacitor, the capacitance C and the loss tangent of the fireproof power capacitor have the same change rule as those of the traditional parallel capacitor; during operation, the capacitance C changes along with the change of the temperature theta of the internal medium of the fireproof power capacitor, and the temperature coefficient of the capacitance of the fireproof power capacitor is a negative value and is generally-3 multiplied by 10-4～5×10-4Within the range of (a), the loss tangent of the all-film capacitor also slightly changes with the dielectric temperature theta; in this example, the fireproof power capacitor is operated at a given voltage and ambient temperatureThe thermal stability test, the capacitance C and the loss tangent are constant values.
specifically, the establishing of the heat conduction process model includes conducting heat generated by internal power loss of the fireproof power capacitor to an inner shell of the fireproof power capacitor, and conducting the heat from the inner shell of the fireproof power capacitor to an outer shell;
establishing a shell heat dissipation power model comprises establishing the heat dissipation capacity Q of the shell of the fireproof power capacitor to the surrounding environment in unit timesNatural convection heat dissipation QconAnd radiation heat dissipation QradThe model of (2);
the establishing of the thermal balance model comprises that when the loss power of the fireproof power capacitor is equal to the heat dissipation power of the shell of the fireproof power capacitor, the heat absorption power of the fireproof power capacitor is equal to zero, so that the temperature of the fireproof power capacitor does not rise any more, and the fireproof power capacitor reaches a thermal balance state under the working condition; establishing a model among the power loss of the fireproof power capacitor, the heat dissipation power of the shell of the fireproof power capacitor and the heat absorption power of the fireproof power capacitor at thermal equilibrium.
specifically, the product information of the fireproof power capacitor, the result of the heat conduction process model, and the result of the shell heat dissipation power model are substituted into the heat balance model in step 130, so that the temperature of the hottest point inside the fireproof power capacitor, the temperature of the inner shell, and the temperature of the shell can be calculated.
in this embodiment, the manner of performing the early warning control on the fireproof power capacitor through the calculated internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor includes multiple manners, including performing real-time comparison on a preset temperature early warning threshold value and the internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor to perform early warning, where the early warning threshold value may be multi-order, and thus forming hierarchical early warning;
specifically, in this embodiment, a first warning threshold and a second warning threshold are set; the first early warning threshold value is smaller than a second early warning threshold value;
when the obtained internal hottest point temperature is below a first early warning threshold value, determining that the influence of the current internal hottest point temperature on the fireproof power capacitor is acceptable, and keeping the fireproof power capacitor to normally work;
when the obtained internal hottest point temperature is between a first early warning threshold value and a second early warning threshold value, the influence of the current internal hottest point temperature on the fireproof power capacitor possibly has a risk, and the current internal hottest point temperature is fed back to related workers through early warning to be artificially confirmed;
when the obtained internal hottest point temperature is above a second early warning threshold value, the influence of the current internal hottest point temperature on the fireproof power capacitor has a large risk, and related workers are warned in time.
FIG. 3 is a flow chart of a BAMY12/2-500-1 WFH-based fire-protection power capacitor temperature early warning method according to an embodiment of the present invention. As shown in fig. 3, the method includes:
specifically, in the present example, the fireproof power capacitor is of the BAMY12/2-500-1WFH type, the product information is shown in Table 1,
TABLE 1 BAMY12/2-500-1WFH type fireproof power capacitor rating parameter
specifically, in this embodiment, the formula for calculating the power loss of the fireproof power capacitor is as follows:
P＝Qtanδ＝ωCU2tanδ
wherein P is the loss power of the fireproof power capacitor, Q is the output capacity of the fireproof power capacitor, U is the voltage of the fireproof power capacitor when thermally stable, ω is the rated frequency of the fireproof power capacitor, C is the fireproof power capacitor capacitance, and tan δ is the loss tangent; specifically, according to DL/T1647-2016, the voltage should be 1.2 times of the rated voltage of the product during thermal stability;
as described in the above embodiments, the capacitance C may change with the temperature θ of the internal medium of the fireproof power capacitor during operation, and the temperature coefficient of capacitance for the fireproof power capacitor is a negative value and is usually-3 × 10-4～5×10-4Within the range of (a), the loss tangent of the all-film capacitor also slightly changes with the dielectric temperature theta; in this example, the fireproof power capacitor was subjected to a thermal stability test at a given voltage and ambient temperature, and the capacitance C and the loss tangent were constant values.
the establishment of the heat conduction process model is the same as the establishment of the heat conduction process model in the above embodiment, specifically, in this embodiment, heat generated by internal power loss is conducted to the inner shell through the element and the impregnant, and since the oil gap thickness of the impregnant of the fireproof power capacitor is in millimeter level, the impregnant has viscosity and does not obviously flow, the temperature distribution curve for conducting the temperature of the internal medium of the fireproof power capacitor to the temperature of the inner shell is generally approximately linearized; the process is consistent with the heat conduction process of the traditional parallel capacitor, the heat conductivity coefficient from the internal medium of the capacitor to the 'inner shell' is generally 1.9-2.1, in the example, lambda is taken1Is 2.0;
the heat of the inner shell of the fireproof power capacitor is conducted to the shell through the fireproof medium, and the fireproof medium is only filled between the inner shell and the shell of the fireproof power capacitor and does not flow obviously, so that the temperature distribution curve of the inner shell of the fireproof power capacitor conducted to the shell is regarded as linear; since only the fireproof medium is filled between the inner shell and the outer shell of the fireproof power capacitor, the heat conductivity coefficient of the process in the embodiment is the heat conductivity coefficient lambda of the fireproof medium2Is 0.54;
therefore, the two processes of the heat conduction of the fireproof power capacitor can regard the temperature distribution curve as a piecewise linear process, and the formula for establishing the heat conduction process model in this example is as follows:
Qf＝λ1(tX-tN)A+λ2(tN-tW)A
wherein Q isfLambda being the heat generation per unit time of the fireproof power capacitor1The heat conductivity coefficient from the internal medium of the fireproof power capacitor to the inner shell is shown; t is tXThe temperature of the hottest point of the fireproof power capacitor medium (the height from the center line of the core to the bottom surface 2/3); t is tNThe temperature of the hottest point of the inner shell of the fireproof power capacitor (the position where the center line of the inner shell is away from the bottom surface 2/3); lambda [ alpha ]2The heat conductivity coefficient from the inner shell to the outer shell of the fireproof power capacitor is set; t is tWIs the fire-proof electric powerThe hottest point temperature of the capacitor case (the height of the center line of the case from the bottom surface 2/3), a, is the effective heat dissipation area of the fireproof power capacitor case.
specifically, in this embodiment, the formula for establishing the shell heat dissipation power model in the preset model is as follows:
Qs＝Qcon+Qrad
wherein Q issIs the heat dissipation per unit time, Q, of the fireproof power capacitor case to the surrounding environmentconFor natural convection heat dissipation, QconIs the radiant heat removal.
Further, the natural convection heat dissipation QconThe formula of (1) is:
Qcon＝α(tW-t0)A
wherein α is the natural convection coefficient of the shell, t0Is the ambient temperature, tWThe temperature of the hottest point of the shell of the fireproof power capacitor is A, and the effective heat dissipation area of the shell of the fireproof power capacitor is A;
because the natural convection heat dissipation coefficient of the shell of the fireproof power capacitor is influenced by factors such as the environment temperature, the shell size, the placement mode and the like, the calculation process is very complicated, the empirical formula is adopted for calculation in the example,
α＝1.5(tW-t0)0.35
radiation heat quantity QradThe formula of (a) is as follows,
Qrad＝5.7ε(tW-t0)4A
wherein epsilon is the shell radiation coefficient;
specifically, in this embodiment, the formula for establishing the thermal equilibrium model in the preset model is as follows:
Pdt＝C`M·d(Δθ)+Qsdt
wherein P is the power loss of the fireproof power capacitor, t is time, and C' is the specific heat capacity of the fireproof power capacitor; m is the mass of the fireproof power capacitor; delta theta is the medium temperature rise of the fireproof power capacitor; qsThe heat dissipation per unit time of the fire-proof power capacitor shell to the surrounding environment;
when the fireproof power capacitor reaches thermal equilibrium, the fireproof power capacitor does not absorb heat any more, and the temperature rise delta theta of the medium is kept constant, namely d (delta theta) is 0; the heat generated by the fireproof power capacitor in unit time is totally dissipated to the surrounding environment, and the formula of the heat balance model can be converted into
Pdt＝Qs＝(Qcon+Qrad)dt
At this time, the fireproof power capacitor reaches a thermal steady state, the heat generated by the fireproof power capacitor is equal to the heat dissipated by the housing, and the internal and external temperatures of the fireproof power capacitor reach a constant value.
in this example, the main parameters of the product under the conditions of the heat stability test are shown in Table 2,
TABLE 2 main parameters of the product under the conditions of the heat stability test
The calculation results and the measurement results are shown in table 3,
TABLE 3 comparison of the calculated results with the measured results
Because the inner shell casing of product can't connect the thermocouple, so can't monitor inner shell casing temperature during the experiment, through comparing with product thermal stability test data, the difference of calculated value and testing value is within 3 ℃, in reasonable receiving range.
in this embodiment, obtain through the calculation the mode that fire prevention power capacitor early warning control was carried out to fire prevention power capacitor's inside hot spot temperature, inlayer casing temperature, shell temperature contains the multiple, include through predetermined temperature early warning threshold with fire prevention power capacitor's inside hot spot temperature, inlayer casing temperature, shell temperature carry out real-time comparison and then carry out the early warning, the early warning threshold can be multistage, forms the early warning of layering.
Specifically, in this embodiment, a first warning threshold and a second warning threshold are set; the first early warning threshold value is smaller than a second early warning threshold value;
when the obtained internal hottest point temperature is below a first early warning threshold value, determining that the influence of the current internal hottest point temperature on the fireproof power capacitor is acceptable, and keeping the fireproof power capacitor to normally work;
when the obtained internal hottest point temperature is between a first early warning threshold value and a second early warning threshold value, the influence of the current internal hottest point temperature on the fireproof power capacitor possibly has a risk, and the current internal hottest point temperature is fed back to related workers through early warning to be artificially confirmed;
when the obtained internal hottest point temperature is above a second early warning threshold value, the influence of the current internal hottest point temperature on the fireproof power capacitor has a large risk, and related workers are warned in time.
Fig. 4 is a structural diagram of a temperature early warning control device based on thermal stability calculation of a fireproof power capacitor according to an embodiment of the present invention. As shown in fig. 4, the apparatus includes:
an obtaining unit 310, wherein one end of the obtaining unit 310 is connected to the power loss calculating unit 320, the model establishing unit 330 and the temperature calculating unit 340 respectively; the obtaining unit 310 is configured to obtain product information of the fireproof power capacitor, where the product information includes a rated voltage, a rated capacity, a rated frequency, a temperature category, a capacitance, a loss tangent, a quality, a specific heat capacity, a thermal conductivity from an internal medium of the fireproof power capacitor to an inner shell, a thermal conductivity from the inner shell to an outer shell of the fireproof power capacitor, an outer shell size, a top surface sleeve diameter, an outer shell effective heat dissipation area, an outer shell radiation coefficient, and an outer shell convection heat dissipation coefficient of the fireproof power capacitor, and send the product information to the loss power calculating unit 320, the model establishing unit 330, and the temperature calculating unit 340;
a power loss calculation unit 320, wherein one end of the power loss calculation unit 320 is connected to the obtaining unit 310, and the other end is connected to the temperature calculation unit 340; the loss power calculation unit 320 is configured to receive the product information sent by the obtaining unit 310, calculate the loss power of the fireproof power capacitor according to the voltage, the rated frequency, the capacitance, and the loss tangent of the fireproof power capacitor when the fireproof power capacitor is thermally stable, and send the loss power of the fireproof power capacitor to the temperature calculation unit 340;
a model establishing unit 330, wherein one end of the model establishing unit 330 is connected with the obtaining unit 310, and the other end is connected with a temperature calculating unit 340; the model establishing unit 330 is configured to receive product information of the fireproof power capacitor, establish a heat conduction process model, a shell heat dissipation power model and a heat balance model according to the product information of the fireproof power capacitor and a preset model, and transmit the heat conduction process model, the shell heat dissipation power model and the heat balance model to the temperature calculating unit 340;
a temperature calculation unit 340, wherein one end of the temperature calculation unit 340 is connected to the obtaining unit 310 and the model establishing unit 330, and the other end is connected to an early warning control unit 350; the temperature calculation unit 340 is configured to calculate an internal hottest point temperature, an inner shell temperature, and a shell temperature of the fireproof power capacitor according to the product information of the fireproof power capacitor, the loss power of the fireproof power capacitor during thermal stability, the heat conduction process model, the shell heat dissipation power model, and the heat balance model, and send the internal hottest point temperature, the inner shell temperature, and the shell temperature of the fireproof power capacitor to the early warning control unit 350;
an early warning control unit 350, wherein one end of the early warning control unit 350 is connected with the temperature calculation unit 340; the early warning control unit 350 is used for receiving the temperature calculation unit 340 and sending the inside hottest point temperature, the inner shell body temperature and the shell temperature of the fireproof power capacitor, and carrying out early warning control on the temperature of the fireproof power capacitor according to the inside hottest point temperature, the inner shell body temperature, the shell temperature and a preset early warning threshold value of the fireproof power capacitor.
Further, the model building unit 330 includes:
a thermal conduction process model module 3301, one end of the thermal conduction process model module 3301 is connected to the obtaining unit 310, and the other end is connected to the temperature calculating unit 340; the thermal conduction process model module 3301 is configured to establish a thermal conduction process model and send the thermal conduction process model to the temperature calculation unit 340;
a housing heat dissipation power model module 3302, one end of the housing heat dissipation power model module 3302 is connected to the obtaining unit 310, and the other end is connected to the temperature calculating unit 340; the housing heat dissipation power model module 3302 is configured to establish a housing heat dissipation power model, and send the housing heat dissipation power model to the temperature calculation unit 340;
a thermal balance model module 3303, one end of the thermal balance model module 3303 is connected with the acquiring unit, and the other end is connected with the temperature calculating unit 340; the thermal equilibrium model module 3303 is used to build a thermal equilibrium model and send the thermal equilibrium model to the temperature calculation unit 340.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Reference to step numbers in this specification is only for distinguishing between steps and is not intended to limit the temporal or logical relationship between steps, which includes all possible scenarios unless the context clearly dictates otherwise.
Moreover, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination.
Various component embodiments of the disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure may also be embodied as device or system programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present disclosure may be stored on a computer-readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The disclosure may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several systems, several of these systems may be embodied by one and the same item of hardware.
The foregoing is directed to embodiments of the present disclosure, and it is noted that numerous improvements, modifications, and variations may be made by those skilled in the art without departing from the spirit of the disclosure, and that such improvements, modifications, and variations are considered to be within the scope of the present disclosure.
Claims (11)
1. A temperature early warning control method based on fireproof power capacitor thermal stability calculation is characterized by comprising the following steps:
acquiring product information of the fireproof power capacitor, wherein the product information comprises rated voltage, rated frequency, capacitance and loss tangent of the fireproof power capacitor;
calculating the loss power of the fireproof power capacitor in the thermal stability according to the voltage, the rated frequency, the capacitance and the loss tangent of the fireproof power capacitor in the thermal stability;
establishing a heat conduction process model, a shell heat dissipation power model and a heat balance model according to the product information of the fireproof power capacitor and a preset model;
calculating the temperature of the internal hottest point, the temperature of an inner shell and the temperature of an outer shell of the fireproof power capacitor according to the product information of the fireproof power capacitor, the loss power of the fireproof power capacitor during thermal stability, the heat conduction process model, the outer shell heat dissipation power model and the heat balance model;
and carrying out early warning control on the temperature of the fireproof power capacitor according to the temperature of the hottest point in the fireproof power capacitor, the temperature of the inner shell, the temperature of the outer shell and a preset early warning threshold value.
2. The method of claim 1, wherein the formula for calculating the power loss of the fireproof power capacitor at thermal equilibrium is:
P＝Qtanδ＝ωCU2tanδ
wherein P is a loss power of the fireproof power capacitor at thermal equilibrium, Q is an output capacity of the fireproof power capacitor, U is a voltage of the fireproof power capacitor at thermal stability, ω is a rated frequency of the fireproof power capacitor, C is the fireproof power capacitor capacitance, and tan δ is a loss tangent of the fireproof power capacitor.
3. The method of claim 1, wherein the modeling the heat conduction process according to the product information of the fireproof power capacitor and a preset model comprises:
conducting heat generated by internal power losses of the fireproof power capacitor to an inner shell of the fireproof power capacitor and conducting the heat from the inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor;
the temperature distribution curve of the heat generated by the internal power loss of the fireproof power capacitor conducted to the inner shell of the fireproof power capacitor and the heat conducted from the inner shell of the fireproof power capacitor to the outer shell of the fireproof power capacitor is regarded as a linearization.
4. The method of claim 3, wherein the predetermined model is modeled as a heat transfer process according to the formula:
Qf＝λ1(tX-tN)A+λ2(tN-tW)A
wherein Q isfIs the heat generation per unit time, lambda, of the fireproof power capacitor1The thermal conductivity from the internal medium of the fireproof power capacitor to the inner shell of the fireproof power capacitor; t is tXThe temperature of the hottest point of the fireproof power capacitor medium is obtained; t is tNThe temperature of the hottest point of the inner shell of the fireproof power capacitor is obtained; lambda [ alpha ]2A thermal conductivity from an inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor; t is tWThe temperature of the hottest point of the shell of the fireproof power capacitor is A, and the effective heat dissipation area of the shell of the fireproof power capacitor is A.
5. The method of claim 1, wherein the formula for establishing the shell heat dissipation power model in the preset model is as follows:
Qs＝Qcon+Qrad
wherein Q issIs the heat dissipation per unit time, Q, of the housing of the fireproof power capacitor to the surroundingsconIs the natural convection heat dissipation per unit time of the housing of the fireproof power capacitor to the surrounding environment, QconIs the radiant heat per unit time of the housing of the fireproof power capacitor to the surrounding environment.
6. The method of claim 5, wherein the housing of the flameproof power capacitor naturally convects heat Q per unit time to the ambient environmentconThe formula of (1) is:
Qcon＝α(tW-t0)A
wherein α is the natural convection coefficient of the shell, t0Is the ambient temperature, tWThe temperature of the hottest point of the shell of the fireproof power capacitor is A, and the effective heat dissipation area of the shell of the fireproof power capacitor is A;
the shell of the fireproof power capacitor radiates heat quantity Q per unit time to the surrounding environmentradThe formula of (a) is as follows,
Qrad＝5.7ε(tW-t0)4A
wherein epsilon is the shell emissivity.
7. The method of claim 6, wherein the natural convection heat dissipation coefficient of the housing is formulated as:
α＝1.5(tW-t0)0.35
8. the method of claim 1, wherein the formula for establishing the thermal equilibrium model in the predetermined model is as follows:
Pdt＝C`M·d(Δθ)+Qsdt
wherein P is the power loss of the fireproof power capacitor, t is the time, C' is the specific heat capacity of the fireproof power capacitor, M is the mass of the fireproof power capacitor, Delta theta is the temperature rise of the medium of the fireproof power capacitor, and QsIs the amount of heat dissipated per unit time by the fire-protected power capacitor enclosure to the surrounding environment.
9. A temperature early warning controlling means based on fire prevention power capacitor thermal stability calculates, its characterized in that, the device includes:
one end of the acquisition unit is respectively connected with the loss power calculation unit, the model establishment unit and the temperature calculation unit; the acquisition unit is used for acquiring product information of the fireproof power capacitor, and rated voltage, rated frequency, capacitance and loss tangent of the fireproof power capacitor;
the device comprises an acquisition unit, a loss power calculation unit and a temperature calculation unit, wherein one end of the acquisition unit is connected with the temperature calculation unit; the loss power calculation unit is used for receiving the product information sent by the acquisition unit, calculating the loss power of the fireproof power capacitor according to the voltage, the rated frequency, the capacitance and the loss tangent of the fireproof power capacitor when the fireproof power capacitor is thermally stable, and sending the loss power of the fireproof power capacitor to the temperature calculation unit;
the model building unit is connected with the acquisition unit at one end and connected with the temperature calculation unit at the other end; the model establishing unit is used for receiving the product information of the fireproof power capacitor, establishing a heat conduction process model, a shell heat dissipation power model and a heat balance model according to the product information of the fireproof power capacitor and a preset model, and transmitting the heat conduction process model, the shell heat dissipation power model and the heat balance model to the temperature calculating unit;
one end of the temperature calculation unit is respectively connected with the acquisition unit, the loss power calculation unit and the model establishment unit, and the other end of the temperature calculation unit is connected with the early warning control unit; the temperature calculation unit is used for calculating the internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor according to the product information of the fireproof power capacitor, the loss power of the fireproof power capacitor, the heat conduction process model, the shell heat dissipation power model and the heat balance model, and sending the internal hottest point temperature, the inner shell temperature and the shell temperature of the fireproof power capacitor to the early warning control unit;
the early warning control unit, one end of the said early warning control unit links with said temperature computational element; the early warning control unit is used for receiving the temperature calculation unit and sending the inside hottest point temperature, the inner shell body temperature and the shell temperature of the fireproof power capacitor, and carrying out early warning control on the temperature of the fireproof power capacitor according to the inside hottest point temperature, the inner shell body temperature, the shell temperature and a preset early warning threshold value of the fireproof power capacitor.
10. The apparatus of claim 9, wherein the model building unit comprises:
a heat conduction process model module, one end of which is connected with the acquisition unit and the other end of which is connected with the temperature calculation unit; the heat conduction process model module is used for establishing a heat conduction process model and sending the heat conduction process model to the temperature calculation unit;
one end of the shell heat dissipation power model module is connected with the acquisition unit, and the other end of the shell heat dissipation power model module is connected with the temperature calculation unit; the shell heat dissipation power model module is used for establishing a shell heat dissipation power model and sending the shell heat dissipation power model to the temperature calculation unit;
one end of the thermal balance model module is connected with the acquisition unit, and the other end of the thermal balance model module is connected with the temperature calculation unit; the thermal balance model module is used for establishing a thermal balance model and sending the thermal balance model to the temperature calculation unit.
11. The apparatus of claim 9, wherein the heat conduction process model module for modeling a heat conduction process comprises:
conducting heat generated by internal power losses of the fireproof power capacitor to an inner shell of the fireproof power capacitor and conducting the heat from the inner shell of the fireproof power capacitor to an outer shell of the fireproof power capacitor;
the temperature distribution curve of the heat generated by the internal power loss of the fireproof power capacitor conducted to the inner shell of the fireproof power capacitor and the heat conducted from the inner shell of the fireproof power capacitor to the outer shell of the fireproof power capacitor is regarded as a linearization.
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