Online monitoring method and system for insulation aging of outgoing cable of new energy station

Abstract

The invention provides an on-line monitoring method for insulation aging of a new energy station sending-out cable. Comprising the following steps: establishing a cable distributed parameter model; establishing a new energy power station rear-end cable and power grid system impedance mathematical model; acquiring and processing three-phase voltage and current of an outlet of the new energy station; calculating a square root ratio coefficient and an insulation change coefficient; judging line insulation conditions at different monitoring moments; and decoupling of two factors causing change of the resonant frequency is realized by using a root ratio curve. According to the method, the change of the resonant frequency caused by the change of the equivalent impedance of the weak power grid can be avoided, and then the insulation aging conditions of the equivalent distributed capacitance and the power transmission cable are estimated by analyzing the change of the resonant frequency of the broadband impedance spectrum of the cable. The method is convenient to implement, the monitoring process is simple, and insulation aging on-line monitoring of the long-distance power transmission cable can be realized so as to guarantee safe operation of a new energy power generation system.

Description

Technical Field

[0001] The present invention relates to the field of cable monitoring technology, and in particular to an online monitoring method for insulation aging faced by transmission cables of a new energy station. Background Art

[0002] Due to the constraints of wind and light resources, most renewable energy power generation bases are concentrated in remote areas such as deserts, Gobi, and grasslands, requiring long-distance transmission cables to transmit electricity to the power grid. However, these areas have large temperature differences between day and night and complex climates, so the insulation conditions of the power transmission cables of renewable energy stations are more severe than those of inland power transmission lines. In response to this situation, it is usually necessary to conduct real-time online monitoring of the insulation conditions of the cables to ensure the safe transmission of electricity.

[0003] For long transmission cables, distributed parameters are usually used for analysis and modeling, that is, each section of the transmission cable can be equivalent to a circuit model. When the insulation of the transmission cable ages, the dielectric constant of the insulation will change, which will cause the equivalent capacitance of the insulation to the ground in the circuit model to change. C L Increase. By estimating C L The size of the insulation can reflect the aging of the transmission cable.

[0004] Common online monitoring methods for transmission cables include partial discharge method, frequency domain reflection method, pulse current method, etc. However, due to the complexity of the cable structure, partial discharge (PD) will undergo multiple reflections and attenuation. At the same time, the cable is noisy and has large interference during operation, so the collected PD signal is extremely weak and easily submerged by noise. The frequency domain reflection method is only suitable for offline monitoring of cable faults due to the mutual interference between the test signal and the signal transmitted in the cable. Therefore, some scholars have proposed a broadband impedance method, because cable aging will affect the equivalent distributed capacitance. C L , the broadband impedance spectrum of the cable will also change accordingly, so the equivalent distributed capacitance can be estimated based on the resonant frequency of the broadband impedance spectrum. C L However, since the real-time fluctuation of the grid-side impedance will also affect the resonance frequency of the broadband impedance spectrum, this method is mostly used for offline testing and rarely used for online monitoring. Summary of the invention

[0005] In view of this, the present invention provides an online monitoring method for the overall insulation aging of the transmission cable of a new energy station, which includes the following steps: Establish cable distributed parameter model; Establish a mathematical model of impedance of the rear-end cables and power grid system of new energy power stations; Collect and process the three-phase voltage and current at the outlet of the new energy station to obtain the broadband impedance spectrum of the back-end system and its series resonant frequency; Calculate the square root ratio coefficient and insulation variation coefficient; Determine the line insulation condition at different monitoring times; The root ratio curve is used to decouple the two factors that cause the resonant frequency change.

[0006] The establishment of the cable distributed parameter model is specifically as follows: According to the model of the cable sent out from the new energy station, the equivalent resistance per unit length of the cable is defined as R L , the equivalent inductance is L L , the equivalent capacitance is C L , the equivalent resistance of the power grid is R g , the equivalent inductance is L g ; The equivalent circuit model in S domain is: .

[0007] The mathematical model of the impedance of the rear-end cables and power grid system of the new energy power station is specifically established as follows: Mathematical model of cable impedance at the back end of new energy power station: ; Mathematical model of power grid system impedance: ; Among them, poly n numL Indicates the number of cable segments. n The back-end system impedance polynomial for the case of segment Z n sys The cable portion of the molecule, poly n numg It is the power grid part; poly n denL is the backend system impedance polynomial Z n sys The cable part of the denominator, poly n deng It is the power grid part; n Indicates the number of cable segments; remember f 1( t 0) indicates the health status of the new energy station transmission cable and the rated operating parameters of the power grid system Zn sys The first series resonant frequency, f 2( t 0) represents the second series resonant frequency.

[0008] The specific steps of collecting and processing the three-phase voltage and current at the outlet of the new energy station are as follows: Superimpose broadband signals; Collect three-phase voltage and current at the outlet of new energy station; Perform Fourier analysis; After dividing the amplitudes of each phase voltage and current at each frequency point, the broadband impedance spectrum Znsys of each phase of the back-end system is obtained; Further get the current running state ( t=t x ) Z n sys The first series resonant frequency f 1( t x ) and the second series resonant frequency f 2( t x ).

[0009] The root ratio curve is specifically a curve approximately fitted by interpolation method, and its meaning is: Define the equivalent impedance of the power grid L g The equivalent inductance parameter L in the cable distributed parameters L The ratio is M: ; Ratio M and back-end system impedance polynomial Z n sys The ratio of the first two roots root1 and root2 of the numerator simplified formula is the root ratio, where the simplified formula is: .

[0010] The meanings of the square root ratio coefficient and the insulation variation coefficient are: According to the first series resonant frequency f 1( t x ) and the second series resonant frequency f 2( t x ), obtain the root ratio coefficient under the current operating state T L ( t x ), and the insulation variation coefficient K C1 ( tx ): ; .

[0011] The determination of the line insulation conditions at different monitoring times is specifically as follows: when f 1( t x )= f 1( t x-1 ), determine that the line insulation condition has not changed; when f 1( t x ) ≠ f 1( t x-1 )and T L ( t x ) =T L ( t x-1 ), determine the equivalent inductance of the power grid L g There is no change, while the line-to-ground capacitance C L changes, in this case the capacitance to ground C L The rate of change is 1 / K C1 ( t x-1 ); when f 1( t x ) ≠ f 1( t x-1 )and T L ( t x ) ≠ T L ( t x-1 ), determine the equivalent inductance of the power grid L g Changes, but the cable-to-ground capacitance is not determined C L If there is a change, the two changes are decoupled by the root ratio curve method.

[0012] The decoupling of two factors causing the change of the resonant frequency by using the root ratio curve is specifically: Using interpolation method, T L ( t x ) value to get the corresponding M The value of the back-end system impedance polynomial Z is solved n sys The first root of the simplified molecular formula is obtained root 1; Combined with the current first series resonant frequency f 1( t x ) Solve the cable-to-ground capacitance in the current state C L Size: .

[0013] In a second aspect, an online monitoring system for insulation aging faced by a new energy station transmission cable is provided, comprising: a first module for establishing a cable distributed parameter model; The second module is used to establish a mathematical model of impedance of the rear-end cables and power grid system of the new energy power station; The third module is used to collect and process the three-phase voltage and current at the outlet of the new energy station; The fourth module is used to calculate the square root ratio coefficient and the insulation variation coefficient; The fifth module is used to determine the line insulation conditions at different monitoring times; The sixth module is used to use the root ratio curve to achieve decoupling of two factors that cause the resonant frequency change.

[0014] According to a third aspect, an electronic device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the above method when executing the computer program.

[0015] Beneficial effects of the present invention: The present invention can avoid the change of resonant frequency caused by the change of equivalent impedance of weak power grid, and then estimate the equivalent distributed capacitance by analyzing the change of resonant frequency of broadband impedance spectrum of cable. C L , monitor the insulation aging of transmission cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention has the following accompanying drawings: Figure 1 Coefficient relationship diagram; Figure 2 A simplified diagram of the system topology and data collection location; Figure 3 Comparison chart of theoretical calculation formula of back-end cable and power grid system impedance and measured impedance data; Figure 4 Root Ratio Curve Example; Figure 5 Distributed circuit and grid impedance models; Figure 6 Overall flow chart of the monitoring method. DETAILED DESCRIPTION

[0017] In order to make the objects, advantages and features of the present invention more obvious, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] An embodiment of an online monitoring method for insulation aging faced by a new energy station transmission cable comprises the following steps: Step 1: Figure 5 According to the model of the cable sent out by the new energy station, the distributed parameter model is established using the manual parameters. The equivalent resistance per unit length of the cable is defined as R L , the equivalent inductance is L L , the equivalent capacitance is C L , the equivalent resistance of the power grid is R g , the equivalent inductance is L g The equivalent circuit model in the s domain is listed as formula (1), and the mathematical model of the impedance of the rear-end cables and power grid system of the new energy power station is established. Z n sys As shown in formula (2) and formula (3), n Indicates the number of cable segments. f 1( t 0) indicates the health status of the new energy station transmission cable and the rated operating parameters of the power grid system Z n sys The first series resonant frequency, f 2( t 0) represents the second series resonant frequency.

[0019] Step 2: According to the model established in step 1, the three-phase voltage and current of the new energy station outlet are continuously collected during system operation and Fourier analysis is performed (such as Figure 1 ), and the amplitude-frequency characteristics of the three-phase voltage and current are obtained respectively; after dividing the amplitude of each phase voltage and current at each frequency point, the broadband impedance spectrum of each phase of the back-end system is obtained. Z n sys (like Figure 3 ), the impedance spectrum includes the impedance of the back-end cables and the power grid system, and records the current operating state ( t=t x ) Z n sys The first series resonant frequency f 1( t x ) and the second series resonant frequency f 2( t x ).

[0020] Step 3: Define the grid equivalent impedance L g Equivalent inductance parameters in cable distributed parameters L L The ratio is M As shown in equation (8) and the back-end system impedance polynomial Z n sys The simplified molecular formula is as follows: The first two roots of formula (7) root 1 and root The fitting curve of the ratio of 2 is the root ratio curve (such as Figure 4 ). Then the interpolation method is used to approximate a curve.

[0021] Step 4: Define the second series resonant frequency at the current monitoring moment f 2( t x ) and the first series resonant frequency f 1( t x ) is the square root ratio coefficient T L ( t x ) as in formula (9). Definition of insulation variation coefficient K C1 ( t x ) as formula (10). Get the current running state ( t=t x )of T L ( t x )and K C1 ( t x )value.

[0022] Step 5: Determine the insulation condition of the line. f 1( t x )= f 1( t x-1), indicating that the line insulation condition has not changed. If the results are not equal, it means that the equivalent inductance of the public power grid L g or line-to-ground capacitance C L changes; if at this time T L ( t x ) =T L ( t x-1 ), indicating the equivalent inductance of the power grid L g There is no change, so it can be determined that the line-to-ground capacitance C L Changes, the degree of change is 1 / K C1 ( t x ); if at this time T L ( t x ) ≠ T L ( t x-1 ), indicating the equivalent inductance of the power grid L g changes have occurred.

[0023] Step 6: Use interpolation method according to T L ( t x ) value to get the corresponding M The value of M Substitute into formula (7) to solve the polynomial and obtain its first root root 1. Combined with the current of the first series resonant frequency f 1( t x ) can be used to calculate the cable-to-ground capacitance in the current state C L The size of is as shown in formula (12), thereby obtaining the insulation state of the transmission cable and realizing the decoupling of the two factors that cause the resonant frequency change.

[0024] The detailed description of the above steps is as follows: ; ; ; Among them, poly n numL Indicates the number of cable segments. nThe back-end system impedance polynomial for the case of segment Z n sys The cable portion of the molecule, poly n numg It is the power grid part; poly n denL is the backend system impedance polynomial Z n sys The cable part of the denominator, poly n deng is the power grid part, and equation (2) represents Z n sys The connection between these four parts.

[0025] Since the series resonant frequency of the back-end system is only Z n sys The molecule is related, and the analysis focuses on formula (4): ; make After calculation, it is found that formula (4) can be written as formula (5). Among them, So The polynomial is a variable, and its coefficient pattern is shown in Figure (1). Its essence is the diagonal of the coefficients of Pascal's triangle.

[0026] ; Transform equation (5) and substitute it into equation (1) h 0 and h g We get formula (6).

[0027] ; The numerator (6) of the back-end system impedance can be written as: ; Definition of grid equivalent inductance L g The inductance per unit length of the cable L L The ratio is M： ; Secondly, the inverter control algorithm is set so that the modulation wave is superimposed every hour. f 1±1kHz and fWideband signals around 2±1kHz. At the same time, when the system is running, the three-phase voltage and current at the outlet of the new energy station are continuously collected and Fourier analysis is performed to obtain the amplitude-frequency characteristics of the three-phase voltage and current respectively; after dividing the amplitude of each phase voltage and current at each frequency point, the broadband impedance spectrum of each phase of the back-end system is obtained. Record the first series resonant frequency in the current operating state f 1( t x ) and the second series resonant frequency f 2( t x ) and obtain the root ratio coefficient under the current operating state T L ( t x ) see formula (9), and the insulation variation coefficient K C1 ( t x )See formula (10).

[0028] ; ; when f 1( t x )= f 1( t x-1 ), indicating that the line insulation condition has not changed.

[0029] when f 1( t x ) ≠ f 1( t x-1 )and T L ( t x ) =T L ( t x-1 ), indicating the equivalent inductance of the power grid L g There is no change, while the line-to-ground capacitance C L In this case, the capacitance to ground C L The rate of change is 1 / K C1 ( t x-1 ).

[0030] when f 1( tx ) ≠ f 1( t x-1 )and T L ( t x ) ≠ T L ( t x-1 ), indicating the equivalent inductance of the power grid L g Changes, but the cable-to-ground capacitance is not determined C L The two changes can be decoupled by the root ratio curve method below.

[0031] The above analysis shows that the equivalent inductance of the power grid is L g or cable-to-ground capacitance C L Will affect the series resonant frequency f n ( t x ) changes, among which f n ( t x ) is the impedance polynomial of the back-end system in the current operating state Z n sys 1st to n series resonant frequency, but the impact effect is different.

[0032] According to formula (11), it can be seen that the equivalent inductance of the power grid is L g Through influence root n To indirectly affect f n ( t x ), and the capacitance to ground C L Direct impact f n ( t x ).

[0033] ; in, root n is the first to the last n A root, along with M changes, root n It's also changing.M and root n There is a unique mapping relationship. Similarly, you can get a series of root 2 / root The value of 1 varies with M The discrete points of the change. Through the interpolation method, a curve can be approximately fitted, and this curve is defined as the root ratio curve. Figure 4 .

[0034] Therefore, the current corresponding M The value of , and then according to polynomial (7) to obtain the current root 1。 Combined with the current first series resonant frequency f 1( t x ) can be used to calculate the cable-to-ground capacitance in the current state C L The size of is shown in formula (12), thereby obtaining the insulation state of the transmission cable and achieving the decoupling of the two factors that cause the resonant frequency change.

[0035] ; Implementation cases based on the above solutions: Build a new energy storage power station model in the simulation software MATLAB / Simulink and set cable parameters in the simulation model R L =0.053Ω / km, L L =0.63mH / km, C L =25nF / km, the grid impedance parameter is R g =1Ω, L g =1mH.

[0036] Three line aging states under three grid impedances are set, with a total of nine sets of data. The simulation parameters in the model are: G1-L1: L g =1mH ; C L =25 1nF / km G1-L2: L g =1mH ; C L =25 1.05nF / km G1-L3: L g=1mH ; C L =25 1.1nF / km G2-L1: L g =2mH ; C L =25 1nF / km G2-L2: L g =2mH ; C L =25 1.05nF / km G2-L3: L g =2mH ; C L =25 1.1nF / km G3-L1: L g =3mH ; C L =25 1nF / km G3-L2: L g =3mH ; C L =25 1.05nF / km G3-L3: L g =3mH ; C L =25 1.1nF / km The following table shows the values ​​of various monitoring parameters when the cable aging status changes and the grid impedance status changes.

[0037]

[0038] According to the above results, when T L When unchanged, it means L g No change. Capacitance to ground C L The rate of change of the parameter K C It can be seen that the online monitoring of insulation aging of long-distance transmission cables is realized.

[0039] Based on the same inventive concept, an embodiment of the present invention also provides an online monitoring system for insulation aging faced by cables sent out of a new energy station.

[0040] It includes: a first module, used for establishing a cable distributed parameter model; The second module is used to establish a mathematical model of impedance of the rear-end cables and power grid system of the new energy power station; The third module is used to collect and process the three-phase voltage and current at the outlet of the new energy station, and obtain the broadband impedance spectrum of the back-end system and its series resonant frequency; The fourth module is used to calculate the square root ratio coefficient and the insulation variation coefficient; The fifth module is used to determine the line insulation conditions at different monitoring times; The sixth module is used to use the root ratio curve to achieve decoupling of two factors that cause the resonant frequency change.

[0041] It should be noted that any process or method description in the embodiments may be understood as representing a module, fragment or portion of a code including one or more executable instructions for implementing steps of a specific logical function or process, and that the scope of the preferred embodiments of the present invention includes alternative implementations in which the functions may not be performed in the order shown or discussed, including performing the functions in a substantially simultaneous manner or in the reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0042] It should be noted that the logic and / or steps in the embodiments, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or equipment (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or equipment and execute instructions), or in combination with these instruction execution systems, devices or equipment. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or equipment, or in combination with these instruction execution systems, devices or equipment. More specific examples of computer-readable media (non-exhaustive list) include the following: an electrical connection with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0043] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0044] A person skilled in the art may understand that all or part of the steps of implementing the above-mentioned embodiment method may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one of the steps of the method embodiment or a combination thereof.

[0045] In addition, each functional module in the embodiment of the present invention may be integrated into a processing module, or each module may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0046] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0047] The above embodiments describe the technical solutions of the present invention in detail. Obviously, the present invention is not limited to the described embodiments. Based on the embodiments of the present invention, people familiar with the technical field can also make various changes accordingly, but any changes that are equivalent or similar to the present invention belong to the scope of protection of the present invention.

[0048] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for online monitoring of insulation aging faced by cables sent out of a new energy station, characterized in that: The steps include: Establish cable distributed parameter model; Establish a mathematical model of impedance of the rear-end cables and power grid system of new energy power stations; Collect and process the three-phase voltage and current at the outlet of the new energy station to obtain the broadband impedance spectrum of the back-end system and its series resonant frequency; Calculate the square root ratio coefficient and insulation variation coefficient; Determine the line insulation condition at different monitoring times; The root ratio curve is used to decouple the two factors that cause the resonant frequency change.

2. The online monitoring method according to claim 1, characterized in that: The establishment of the cable distributed parameter model is specifically as follows: According to the model of the cable sent out from the new energy station, the equivalent resistance per unit length of the cable is defined as R L , the equivalent inductance is L L , the equivalent capacitance is C L , the equivalent resistance of the power grid is R g , the equivalent inductance is L g ; The equivalent circuit model in the S domain is: 。 3. The online monitoring method according to claim 2, characterized in that: The mathematical model of the impedance of the rear-end cables and power grid system of the new energy power station is specifically established as follows: Mathematical model of cable impedance at the back end of new energy power station: ； Mathematical model of power grid system impedance: ； Among them, poly n numL Indicates the number of cable segments. n The back-end system impedance polynomial for the case of segment Z n sys The cable portion of the molecule, poly n numg It is the power grid part; poly n denL is the backend system impedance polynomial Z n sys The cable part of the denominator, poly n deng It is the power grid part; n Indicates the number of cable segments; remember f 1( t 0) indicates the health status of the new energy station transmission cable and the rated operating parameters of the power grid system Z n sys The first series resonant frequency, f 2( t 0) represents the second series resonant frequency.

4. The online monitoring method according to claim 3, characterized in that: The specific steps of collecting and processing the three-phase voltage and current at the outlet of the new energy station are as follows: Superimpose broadband signals; Collect three-phase voltage and current at the outlet of new energy station; Perform Fourier analysis; After dividing the amplitudes of each phase voltage and current at each frequency point, the broadband impedance spectrum Z nsys of each phase of the back-end system is obtained; Further get the current running state ( t=t x ) Z n sys The first series resonant frequency f 1( t x ) and the second series resonant frequency f 2( t x ).

5. The online monitoring method according to claim 4, characterized in that: The root ratio curve is specifically a curve approximately fitted by interpolation method, and its meaning is: Define the equivalent impedance of the power grid L g The equivalent inductance parameter L in the cable distributed parameters L The ratio is M: ； Ratio M and back-end system impedance polynomial Z n sys The ratio of the first two roots root1 and root2 of the numerator simplified formula is the root ratio, where the simplified formula is: 。 6. The online monitoring method according to claim 4, characterized in that: The meanings of the square root ratio coefficient and the insulation variation coefficient are: According to the first series resonant frequency f 1( t x ) and the second series resonant frequency f 2( t x ), obtain the root ratio coefficient under the current operating state T L ( t x ), and the insulation variation coefficient K C1 ( t x ): ； 。 7. The online monitoring method according to claim 6, characterized in that: The determination of the line insulation conditions at different monitoring times is specifically as follows: when f 1( t x )= f 1( t x-1 ), determine that the line insulation condition has not changed; when f 1( t x ) ≠ f 1( t x-1 )and T L ( t x ) =T L ( t x-1 ), determine the equivalent inductance of the power grid L g There is no change, while the line-to-ground capacitance C L changes, in this case the capacitance to ground C L The rate of change is 1 / K C1 ( t x-1 ); when f 1( t x ) ≠ f 1( t x-1 )and T L ( t x ) ≠ T L ( t x-1 ), determine the equivalent inductance of the power grid L g Changes, but the cable-to-ground capacitance is not determined C L If there is a change, the two changes are decoupled by the root ratio curve method.

8. The online monitoring method according to claim 7, characterized in that: The decoupling of two factors causing the change of the resonant frequency is achieved by using the root ratio curve, specifically: Using interpolation method, T L ( t x ) value to get the corresponding M The value of the back-end system impedance polynomial Z is solved n sys The first root of the simplified molecular formula is obtained root 1; Combined with the current first series resonant frequency f 1( t x ) Solve the cable-to-ground capacitance in the current state C L Size: 。 9. An online monitoring system for insulation aging of cables sent out of a new energy station, characterized in that: include: The first module is used to establish a cable distributed parameter model; The second module is used to establish a mathematical model of impedance of the rear-end cables and power grid system of the new energy power station; The third module is used to collect and process the three-phase voltage and current at the outlet of the new energy station; The fourth module is used to calculate the square root ratio coefficient and the insulation variation coefficient; The fifth module is used to determine the line insulation conditions at different monitoring times; The sixth module is used to use the root ratio curve to achieve decoupling of two factors that cause the resonant frequency change.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the online monitoring method described in any one of claims 1 to 8 is implemented.

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