CN114527331A - Capacitor analysis method and system - Google Patents
Capacitor analysis method and system Download PDFInfo
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- CN114527331A CN114527331A CN202210126569.7A CN202210126569A CN114527331A CN 114527331 A CN114527331 A CN 114527331A CN 202210126569 A CN202210126569 A CN 202210126569A CN 114527331 A CN114527331 A CN 114527331A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Abstract
The invention discloses a capacitor analysis method and a system, comprising the following steps: collecting a current effective value of a bus, and acquiring a transient event caused by capacitor switching by taking the change rate of the current effective value exceeding a first threshold as a trigger condition; acquiring transient power quality data before and after switching of a capacitor based on a transient event to generate a harmonic voltage value and a harmonic current value; respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance along with time change according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor; acquiring the temperature rise speed of the capacitor under a transient event, and acquiring a second change rule of capacitance along with temperature change; and judging whether the capacitor has a fault or not according to the first change rule and the second change rule. The invention provides an actual measurement basis for the research of related problems such as capacitor fault analysis and harmonic impedance calculation.
Description
Technical Field
The invention relates to the technical field of capacitance quality analysis, in particular to a capacitor analysis method and system.
Background
The reactive compensation cabinet is a power device which can play a role in improving the power factor of a power grid in a power supply system, can reduce the loss of a power supply transformer and a transmission line, improves the power supply efficiency, improves the power supply environment, and is relatively common in the power supply system. The electric power supply and utilization system is a complex electromagnetic environment, all electrical equipment operates in the electric energy quality environment, if the electric energy quality environment exceeds the bearing capacity of the reactive compensation cabinet, damage can be caused to the reactive compensation cabinet, and when the damage is accumulated to a certain degree, the reactive compensation cabinet can be damaged. In turn, the operation of electrical equipment at potential risk can also affect the development of changes in its power quality environment. Therefore, based on the constraint of the power quality environment borne by the reactive compensation cabinet in the design stage, the whole-course early warning is carried out on the operation of the reactive compensation cabinet from the perspective of asset life cycle management, and the method is a necessary means for ensuring the safe and reliable operation of the reactive compensation cabinet.
At present, the low-voltage reactive power compensation cabinet in China basically comprises a controller, a plurality of groups of switching switches, a plurality of groups of capacitors, corresponding switching state indicator lamps and the like. Due to the existence of harmonic waves, the capacitor is easy to generate heat, noise is increased, the capacitor is in failure, and further normal operation of related equipment is influenced. The method has the advantages that the fault type, the fault strength and the fault evolution trend are judged by detecting the partial discharge ultrasonic signals excited by the capacitor fault, and the automatic early warning of the capacitor fault is realized.
The fault detection of the capacitor is a precondition for analyzing and preventing the capacitor fault. At present, the traditional capacitor fault detection method is usually carried out off-line. However, the off-line detection of the capacitor in practical application often has the following defects:
the number of capacitors is large, the capacitors cannot be effectively monitored in normal operation by off-line detection, and trend information of each group of capacitors in the capacity change process cannot be positioned;
secondly, the traditional off-line detection method is to acquire capacitor fault group information after the capacitor fault develops to a certain degree to cause the action of the capacitor protection device, so that the advance prejudgment cannot be realized, and the accident can be found and prevented earlier and more timely.
Disclosure of Invention
In order to solve the above problems, the present application provides a capacitor analysis method, including the steps of:
collecting a current effective value of a bus, and acquiring a transient event caused by capacitor switching by taking the change rate of the current effective value exceeding a first threshold as a trigger condition;
acquiring transient power quality data before and after switching of a capacitor based on a transient event, and generating a harmonic voltage value and a harmonic current value through Fourier transform;
respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance along with time change according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor;
acquiring the temperature rise speed of the capacitor under a transient event, and acquiring a second change rule of capacitance along with temperature change;
and judging whether the capacitor has a fault or not according to the first change rule and the second change rule.
Preferably, the step of determining whether the capacitor has a fault according to the first variation rule and the second variation rule includes: acquiring the switching times of the capacitor by acquiring the occurrence times of the transient event, and generating a third change rule of capacitance along with the switching times of the capacitor according to the switching times of the capacitor;
and judging whether the capacitor has a fault according to the first change rule, the second change rule and the third change rule.
Preferably, the step of determining whether the capacitor has a fault according to the first change rule, the second change rule, and the third change rule includes: generating a first fault diagnosis model according to the first change rule and the third change rule, wherein the first fault diagnosis model is used for predicting the first probability of the capacitor fault by collecting the switching times of the capacitor;
generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor;
generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting the third probability of the capacitance fault by collecting the switching times and the heating rate of the capacitor;
judging whether the capacitor fails or not according to the first probability and/or the second probability;
and/or judging whether the capacitor is in fault or not according to the third probability.
Preferably, the step of generating the harmonic voltage value and the harmonic current value is followed by: and acquiring the harmonic impedance value of the capacitor at the bus according to the generated harmonic voltage value and the harmonic current value, and positioning the capacitor according to the harmonic impedance value.
Preferably, in the process of obtaining the harmonic impedance value, the calculation formula of the harmonic impedance value is:
wherein, Z represents the harmonic impedance value, V1 represents the harmonic voltage value before the capacitor is switched, V2 represents the harmonic voltage value after the capacitor is switched, I2 represents the harmonic current value after the capacitor is switched, and I1 represents the harmonic current value before the capacitor is switched.
Preferably, in the process of obtaining the capacitance of the capacitor, the capacitance is calculated by the formula:
wherein In is an nth harmonic current vector; un is an n-th harmonic voltage vector; l is the reactance value of the small reactance of the capacitor in series connection; UNn is neutral point n-th harmonic voltage vector; c is the capacitance of the capacitor; n is the harmonic frequency; j is an imaginary unit; w is the fundamental angular frequency.
The invention also discloses a capacitor analysis system, comprising:
the transient event acquisition module is used for acquiring a transient event caused by switching of the capacitor by acquiring a current effective value of the bus and taking the change rate of the current effective value exceeding a first threshold as a trigger condition;
the data acquisition and processing module is used for acquiring transient electric energy quality data before and after switching of the capacitor based on a transient event, and generating a harmonic voltage value and a harmonic current value through Fourier transform;
the first data analysis module is used for respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance changing along with time according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor;
the second data analysis module is used for acquiring a second change rule of capacitance along with temperature change by acquiring the temperature rise speed of the capacitor under a transient event;
and the capacitor fault diagnosis module is used for judging whether the capacitor has faults or not according to the first change rule and the second change rule.
Preferably, the capacitor analysis system further comprises a third data analysis module, which is used for acquiring the switching times of the capacitor by collecting the occurrence times of the transient event, and generating a third change rule of capacitance along with the switching times of the capacitor according to the switching times of the capacitor;
the capacitor fault diagnosis module is also used for judging whether the capacitor has faults or not according to the first change rule, the second change rule and the third change rule.
Preferably, the capacitor analysis system further comprises a fault prediction module for generating a fault diagnosis model for predicting faults of the capacitor according to the first change rule, the second change rule and the third change rule, wherein,
generating a first fault diagnosis model according to the first change rule and the third change rule, wherein the first fault diagnosis model is used for predicting the first probability of the capacitor fault by collecting the switching times of the capacitor;
generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor;
generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting the third probability of the capacitance fault by collecting the switching times and the heating rate of the capacitor;
judging whether the capacitor fails or not according to the first probability and/or the second probability;
and/or judging whether the capacitor is in fault or not according to the third probability.
Preferably, the capacitor analysis system further includes a fault location module, configured to obtain a harmonic impedance value of the capacitor at the bus according to the generated harmonic voltage value and the harmonic current value, and locate the capacitor according to the harmonic impedance value.
The invention discloses the following technical effects:
the invention does not need special capacitor capacity measuring equipment, and can save investment cost to the maximum extent;
according to the technical scheme, harmonic monitoring can be carried out during the operation of the system, the normal operation of the system is not influenced, and the monitoring result can meet the requirements of real-time performance, integrity and accuracy by carrying out harmonic monitoring on the capacitor;
the invention aims at the statistics of capacitor switching times, the transient process of capacitor switching, the harmonic impedance condition of a system during capacitor switching and the like; the system and the method reach the engineering practical level, and provide an actual measurement basis for researching related problems such as the influence of capacitor switching on a power grid, capacitor fault analysis and harmonic impedance calculation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a capacitor analysis method according to the present invention.
Fig. 2 is a schematic connection diagram of a capacitor analysis system according to an embodiment of the present application.
Fig. 3 is a schematic diagram illustrating a curve diagram of a capacitor analysis system according to an embodiment of the present disclosure.
Fig. 4 is a table display diagram of a capacitor analysis system according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
The present application provides a capacitor analysis method, and fig. 1 is a flow chart of the capacitor analysis method according to the present invention.
As shown in fig. 1, a capacitor analysis method includes the steps of:
s10: and acquiring a current effective value of the bus, and acquiring a transient event caused by switching of the capacitor by taking the change rate of the current effective value exceeding a first threshold as a trigger condition.
S20: based on the transient event, transient power quality data before and after the capacitor is switched are collected, and a harmonic voltage value and a harmonic current value are generated through Fourier transform.
S30: and respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance along with the change of time according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor.
S40: and acquiring the temperature rise speed of the capacitor under the transient event to obtain a second change rule of the capacitance along with the temperature change.
S50: and judging whether the capacitor has a fault or not according to the first change rule and the second change rule.
Illustratively, in the monitoring of the capacitance reactive power compensation cabinet, by performing harmonic wave monitoring on the capacitor during the operation of the system, the fault capacitor can be found in time without influencing the normal operation of the system, so as to facilitate the timely maintenance and operation of the reactive power compensation cabinet system. It should be noted that the first threshold is preferably 80%, and other values may be selected as the trigger condition in practical applications, which is not limited in the present application.
Preferably, in the process of acquiring the transient event, the switching times of the capacitor are acquired by acquiring the occurrence times of the transient event, and a third change rule of the capacitance along with the switching times of the capacitor is generated according to the switching times of the capacitor;
and judging whether the capacitor has a fault according to the first change rule, the second change rule and the third change rule.
The capacitor is monitored at multiple levels and angles, the misjudgment probability can be reduced, and the coverage rate of monitoring and early warning is increased. During switching operation, the capacitance of the capacitor changes sharply with time, which means that the capacitor has a high probability of failure. During the switching operation, the capacitance of the capacitor changes sharply with the rise of the temperature, which means that the probability of the capacitor being in fault is high. During the switching operation, the capacitance of the capacitor changes sharply with the increase of the switching times, which means that the capacitor has a high probability of failure.
Illustratively, the probability of damage of the capacitor is X1 according to the first variation rule, and the probability of damage of the capacitor is X2 … … according to the m-th variation rule.
Alternatively, the total damage probability X of the capacitor may be calculated according to the following formula:
alternatively, the total damage probability X of the capacitor can also be calculated according to the following formula:
X＝1-(1-X1)*(1-X2)*…(1-Xm)。 (2)
illustratively, in 8-hour monitoring, when the capacitance of the capacitor changes by more than 3%, the probability of the capacitor being damaged is 16%; when the capacitance of the capacitor changes by more than 5% under the condition that the temperature is increased from 20 ℃ to 35 ℃, the probability of the capacitor being damaged is 25%; illustratively, when the capacitance of the capacitor changes by more than 4% during the switching times from 5 to 30, the probability of the capacitor being damaged is 36%. If at least two of these conditions occur simultaneously with one capacitor, the probability of the capacitor being damaged may increase, for example, the probability of failure may increase to 70% or 95%. If the first two conditions occur simultaneously and calculation is carried out according to the formula (1), the damage probability of the capacitor is increased to 81% rapidly; the damage probability of the capacitor is mildly raised to 37% by calculation according to equation (2). If the three conditions occur simultaneously and are calculated according to the formula (1), the damage probability of the capacitor is increased to 225% rapidly; the damage probability of the capacitor is mildly raised to 60% by calculation according to equation (2).
According to the calculation result, the technical scheme can acquire data in real time in the operation process of the capacitor, and quantitatively calculate the damage probability of the capacitor so as to assist a user to do maintenance work in time. It should be noted that, in practical applications, the above formula may be selected or further fused with the above formula or the calculation result thereof according to the situation, so as to quantify the damage probability of the capacitor. However, other calculation formulas may be selected or fused in the technical idea of the present application, and the present application is not limited thereto.
Preferably, in the process of judging whether the capacitor fails, a first fault diagnosis model is generated according to the first change rule and the third change rule and used for predicting the first probability of the capacitor failing by collecting the switching times of the capacitor.
And generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor.
And generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting the third probability of the capacitance fault by collecting the switching times and the heating rate of the capacitor.
Judging whether the capacitor fails or not according to the first probability and/or the second probability; and/or determining whether the capacitor fails according to the third probability.
In the process of judging the fault probability of the capacitor according to the first change rule, the second change rule and the third change rule, the fault probability value of the capacitor can be used as the final output of the prediction model by establishing the prediction model and taking the first change rule and the second change rule under different conditions as input. As can be appreciated, the predictive model can be obtained after big data training in an intelligent machine learning manner.
Illustratively, in the running process of the system, a large amount of diagnosis data of a first change rule, a second change rule and a third change rule are collected, and fault models are trained respectively in a machine intelligent learning mode. And after the model with a certain training amount is completed, good identification capability can be established, and early warning characteristics of capacitor faults can be found comprehensively from the changes of the first change rule, the second change rule and the third change rule.
Further preferably, in the process of generating the harmonic voltage value and the harmonic current value, the harmonic impedance value of the capacitor at the bus is obtained according to the generated harmonic voltage value and the generated harmonic current value, and the capacitor is positioned according to the harmonic impedance value.
In many electrical systems such as reactive power compensation cabinets and the like, a capacitor bank consisting of a plurality of capacitors exists, so that different impedances of the capacitors corresponding to different positions of a bus can be obtained by calculating harmonic impedance values of the capacitors at the bus. And once a fault capacitor occurs, the impedance value of the capacitor at the position can be obviously different from the impedance values of the capacitors at other positions, so that the fault capacitor can be positioned, and the fault capacitor can be quickly found to perform corresponding maintenance work.
Further preferably, in the process of obtaining the harmonic impedance value, the calculation formula of the harmonic impedance value is:
wherein, Z represents the harmonic impedance value, V1 represents the harmonic voltage value before the capacitor is switched, V2 represents the harmonic voltage value after the capacitor is switched, I2 represents the harmonic current value after the capacitor is switched, and I1 represents the harmonic current value before the capacitor is switched.
Further preferably, in the process of obtaining the capacitance of the capacitor, the capacitance is calculated by the formula:
wherein In is an nth harmonic current vector; un is an n-th harmonic voltage vector; l is the reactance value of the small reactance of the capacitor in series connection; u shapeNnIs neutral point nth harmonic voltage vector; c is the capacitance of the capacitor; n is the harmonic frequency; j is an imaginary unit; w is the fundamental angular frequency.
A sine wave with a certain frequency and the maximum amplitude is called the fundamental wave. These wavelets above the fundamental frequency are called harmonics. Harmonics are sub-components obtained by fourier series decomposition of a periodic non-sinusoidal alternating current, which are greater than an integral multiple of the frequency of a fundamental wave, and are generally called higher harmonics, while fundamental waves are components having the same frequency as the power frequency (50 Hz). Interference of higher harmonics is a big "nuisance" in current power systems that affects the quality of the power. In a capacitor bank with a large capacity, a small amount of higher harmonic components in the voltage can generate a large higher harmonic current in the capacitor, which may overload the capacitor in a serious case. For this purpose, a reactor can be connected in series in each group of capacitors to limit the higher harmonic currents.
The definition of the harmonic wave of the power supply system is that the Fourier series decomposition is carried out on the periodic non-sinusoidal electric quantity, besides the component with the same frequency as the fundamental wave of the power grid, a series of components with the frequency larger than the fundamental wave of the power grid are obtained, and the part of the electric quantity is called as the harmonic wave. The ratio of the harmonic frequency to the fundamental frequency (n ═ fn/f1) is referred to as the harmonic order. Non-integer multiples of harmonics, known as Non-harmonics (Non-harmonics) or fractional harmonics, are sometimes present in the grid.
By using the formula, the capacitance of the capacitor can be conveniently calculated through the harmonic current vector, the harmonic voltage vector and other specific parameters, and the requirement of dynamically monitoring the capacitance of the capacitor in work is met.
The invention also discloses a capacitor analysis system, and fig. 2 is a connection schematic diagram of the capacitor analysis system according to an embodiment of the application.
Referring to fig. 2, the capacitor analysis system includes:
the transient event acquisition module 1 is configured to acquire a transient event caused by switching of the capacitor by acquiring a current effective value of the bus and using a change rate of the current effective value exceeding a first threshold as a trigger condition.
And the data acquisition and processing module 2 is used for acquiring transient electric energy quality data before and after switching of the capacitor based on the transient event, and generating a harmonic voltage value and a harmonic current value through Fourier transform.
The first data analysis module 3 is configured to generate a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and obtain the capacitance of the capacitor and a first change rule of the capacitance changing with time according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor.
And the second data analysis module 4 is used for acquiring a second change rule of capacitance along with temperature change by acquiring the temperature rise speed of the capacitor under the transient event.
And the capacitor fault diagnosis module 5 is used for judging whether the capacitor has faults or not according to the first change rule and the second change rule.
Illustratively, in the monitoring of the capacitance reactive power compensation cabinet, by performing harmonic monitoring on the capacitor during the operation of the system, the fault capacitor can be found in time without influencing the normal operation of the system, so that the system can be maintained and operated in time. It should be noted that the first threshold is preferably 80%, and other values may be selected as the trigger condition in practical applications, which is not limited in the present application.
Further preferably, the capacitor analysis system further comprises a third data analysis module, which is used for acquiring the switching times of the capacitor by collecting the occurrence times of the transient event, and generating a third change rule of the capacitance along with the switching times of the capacitor according to the switching times of the capacitor.
The capacitor fault diagnosis module is also used for judging whether the capacitor has faults or not according to the first change rule, the second change rule and the third change rule.
The capacitor is monitored at multiple levels and angles, the misjudgment probability can be reduced, and the coverage rate of monitoring and early warning is increased. During switching operation, the capacitance of the capacitor changes sharply with time, which means that the capacitor has a high probability of failure. During the switching operation, the capacitance of the capacitor changes sharply with the rise of the temperature, which means that the probability of the capacitor being in fault is high. In the switching process, the capacitance of the capacitor changes sharply with the increase of the switching times, which represents that the capacitor has a high probability of failure.
Illustratively, the probability of damage of the capacitor is X1 according to the first variation rule, and the probability of damage of the capacitor is X2 … … according to the m-th variation rule.
Alternatively, the total damage probability X of the capacitor may be calculated according to the following formula:
alternatively, the total damage probability X of the capacitor can also be calculated according to the following formula:
X＝1-(1-X1)*(1-X2)*…(1-Xm)。 (2)
illustratively, there is a 16% probability of a capacitor being damaged when its capacitance changes by more than 3% during an 8 hour monitoring; when the capacitance of the capacitor changes by more than 5% under the condition that the temperature is increased from 20 ℃ to 35 ℃, the probability of the capacitor being damaged is 25%; for example, when the capacitance of the capacitor changes by more than 4% in the process of switching times from 5 times to 30 times, the probability of the capacitor being damaged is 36%. If at least two of these conditions occur simultaneously with one capacitor, the probability of damage to the capacitor may increase, such as a failure probability of 70% or 95%. If the first two conditions occur simultaneously and calculation is carried out according to the formula (1), the damage probability of the capacitor is increased to 81% rapidly; the damage probability of the capacitor is mildly raised to 37% by calculation according to equation (2). If the three conditions occur simultaneously and calculation is carried out according to the formula (1), the damage probability of the capacitor is increased to 225% rapidly; the damage probability of the capacitor is mildly raised to 60% by calculation according to equation (2).
According to the calculation result, the technical scheme can acquire data in real time in the operation process of the capacitor, and quantitatively calculate the damage probability of the capacitor so as to assist a user to do maintenance work in time. It should be noted that, in practical applications, the above formula may be selected or further fused or the calculation result thereof may be selected according to the situation, so as to quantify the damage probability of the capacitor. However, other calculation formulas may be selected or fused in the technical idea of the present application, and the present application is not limited thereto.
Further preferably, the capacitor analysis system further includes a fault prediction module, which generates a fault diagnosis model for predicting faults of the capacitor according to the first change rule, the second change rule, and the third change rule, wherein:
and generating a first fault diagnosis model according to the first change rule and the third change rule, wherein the first fault diagnosis model is used for predicting the first probability of the capacitor fault by collecting the switching times of the capacitor.
And generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor.
And generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting the third probability of the capacitance fault by collecting the switching times and the heating rate of the capacitor.
Judging whether the capacitor fails or not according to the first probability and/or the second probability; and/or judging whether the capacitor is in fault or not according to the third probability.
In the process of judging the fault probability of the capacitor according to the first change rule, the second change rule and the third change rule, the fault probability value of the capacitor can be used as the final output of the prediction model by establishing the prediction model and taking the first change rule and the second change rule under different conditions as input. As can be appreciated, the predictive model can be obtained after big data training in an intelligent machine learning manner.
Illustratively, in the running process of the system, a large amount of diagnosis data of a first change rule, a second change rule and a third change rule are collected, and fault models are trained respectively in a machine intelligent learning mode. And after the model with a certain training amount is completed, good identification capability can be established, and early warning characteristics of capacitor faults can be found comprehensively from the changes of the first change rule, the second change rule and the third change rule.
Further preferably, the capacitor analysis system further includes a fault location module, configured to obtain a harmonic impedance value of the capacitor at the bus according to the generated harmonic voltage value and the harmonic current value, and locate the capacitor according to the harmonic impedance value.
In many electrical systems such as reactive power compensation cabinets and the like, a capacitor bank consisting of a plurality of capacitors is provided, and then different impedances of the capacitors corresponding to different positions of a bus can be obtained by calculating harmonic impedance values of the capacitors at the bus. And once a fault capacitor occurs, the impedance value of the capacitor at the position can be obviously different from the impedance values of the capacitors at other positions, so that the fault capacitor can be positioned, and the fault capacitor can be quickly found to perform corresponding maintenance work.
In one embodiment, in the process of judging the state of the capacitor, the capacitor analysis system collects and acquires multiple parameters related to the capacitor for display, so that managers can check and verify the operation condition of the system in time. Fig. 3 is a schematic diagram illustrating a curve diagram of a capacitor analysis system according to an embodiment of the present disclosure. Fig. 4 is a table display diagram of a capacitor analysis system according to an embodiment of the application.
Referring to fig. 3 and 4, the data shown in the system may include current, voltage, power factor, etc. The data period shown can be parameter data at different time points in a day, or parameter data averaged on different days in a month, or parameter data averaged every month in several months.
With continued reference to fig. 3 and 4, the system may count the maximum value, the minimum value, the average value, the maximum time, and the minimum time of each parameter item, and the maximum value, the minimum value, the average value, the maximum time, and the minimum time are labeled in a form of a table or a curve, so that the user can conveniently check the operation condition of the capacitor in real time. The system may present the data collected to the capacitor in a variety of forms, such as a graph or table. If the graph display form is adopted, the data change trend of the parameters can be displayed by changing the parameters of the abscissa and the ordinate, and if the graph display form is adopted, the data condition of the parameters is displayed by selecting the question stems of the tables.
Illustratively, when the system judges the capacitor fault, the system timely sends out fault early warning to facilitate the maintenance work of the capacitor. The failure early warning mode can include terminal display, light warning, information notification, mail sending, call dialing and the like, so as to report the abnormal state of the capacitor at the first time as far as possible.
Through the technical design, the problem that an enterprise cannot inquire the capacity change of the capacitor in real time is solved; and relevant indexes are obtained through collection of multiple capacitor relevant parameter data through calculation, changes of the indexes are displayed in various forms such as a curve graph or a table, enterprises can visually see the change situation of capacitor relevant energy consumption data during operation, and corresponding countermeasures are taken. Through the design of the prediction model, the technical support of fault prediction is provided for enterprises, and a reference basis is provided for circuit maintenance of the enterprises.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus once an item is defined in one figure, it need not be further defined and explained in subsequent figures, and moreover, the terms "first", "second", "third", etc. are used merely to distinguish one description from another and are not to be construed as indicating or implying relative importance.
It should be noted that step numbers such as S10 and S20 are used herein for the purpose of more clearly and briefly describing the corresponding contents, and do not constitute a substantial limitation on the sequence, and those skilled in the art may perform S20 first and then perform S10 in the specific implementation, which should be within the scope of the present application.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the present invention in its spirit and scope. Are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A capacitor analysis method, comprising the steps of:
collecting a current effective value of a bus, and acquiring a transient event caused by capacitor switching by taking the change rate of the current effective value exceeding a first threshold as a trigger condition;
acquiring transient power quality data before and after the capacitor is switched based on the transient event, and generating a harmonic voltage value and a harmonic current value through Fourier transform;
respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance changing along with time according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor;
acquiring the temperature rise speed of the capacitor under a transient event, and acquiring a second change rule of the capacitance along with the change of temperature;
and judging whether the capacitor has a fault or not according to the first change rule and the second change rule.
2. The capacitor analysis method according to claim 1, wherein the step of determining whether the capacitor has a fault according to the first variation rule and the second variation rule comprises:
acquiring the occurrence frequency of the transient event, acquiring the switching frequency of the capacitor, and generating a third change rule of the capacitance along with the switching frequency of the capacitor according to the switching frequency of the capacitor;
and judging whether the capacitor breaks down or not according to the first change rule, the second change rule and the third change rule.
3. The capacitor analysis method according to claim 2, wherein the step of determining whether the capacitor has a fault according to the first change rule, the second change rule, and the third change rule comprises:
generating a first fault diagnosis model according to the first change rule and the third change rule, wherein the first fault diagnosis model is used for predicting a first probability of the capacitor fault by collecting the switching times of the capacitor;
generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor;
generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting a third probability of the capacitance fault by collecting the switching times and the temperature rise speed of the capacitor;
and judging whether the capacitor fails or not according to the first probability, the second probability and/or the third probability.
4. The capacitor analysis method according to any one of claims 1-3, wherein the step of generating harmonic voltage and harmonic current values is followed by:
and acquiring a harmonic impedance value of the capacitor at the bus according to the harmonic voltage value and the harmonic current value, and positioning the capacitor according to the harmonic impedance value.
5. The capacitor analysis method according to claim 4, characterized in that:
the calculation formula of the harmonic impedance value is as follows:
wherein Z represents a harmonic impedance value, V1Represents the harmonic voltage value V before the capacitor is switched2Represents the harmonic voltage value I after the capacitor is switched2Represents the harmonic current value I after the capacitor is switched1Representing the harmonic current value before capacitor switching.
6. The capacitor analysis method according to claim 1, characterized in that:
the calculation formula of the capacitance is as follows:
wherein, InIs an nth harmonic current vector; u shapenIs an nth harmonic voltage vector; l is the reactance value of the small reactance of the capacitor in series connection; u shapeNnIs neutral point nth harmonic voltage vector; c is the capacitance of the capacitor; n is the harmonic frequency; j is an imaginary unit; w is the fundamental angular frequency.
7. A capacitor analysis system, comprising:
the transient event acquisition module is used for acquiring a transient event caused by switching of a capacitor by acquiring a current effective value of a bus and taking the change rate of the current effective value exceeding a first threshold as a trigger condition;
the data acquisition and processing module is used for acquiring transient electric energy quality data before and after the capacitor is switched based on the transient event, and generating a harmonic voltage value and a harmonic current value through Fourier transform;
the first data analysis module is used for respectively generating a harmonic voltage vector and a harmonic current vector according to the harmonic voltage value and the harmonic current value, and acquiring the capacitance of the capacitor and a first change rule of the capacitance changing along with time according to the neutral point harmonic voltage vector and the fundamental wave angular frequency of the capacitor;
the second data analysis module is used for acquiring a second change rule of the capacitance along with the temperature change by acquiring the temperature rise speed of the capacitor under a transient event;
and the capacitor fault diagnosis module is used for judging whether the capacitor has faults or not according to the first change rule and the second change rule.
8. The capacitor analysis system of claim 7, wherein:
the capacitor analysis system further comprises a third data analysis module, which is used for acquiring the switching times of the capacitor by collecting the occurrence times of the transient event, and generating a third change rule of the capacitance along with the switching times of the capacitor according to the switching times of the capacitor;
the capacitor fault diagnosis module is further used for judging whether the capacitor has faults or not according to the first change rule, the second change rule and the third change rule.
9. The capacitor analysis system of claim 8, wherein:
the capacitor analysis system further comprises a fault prediction module for generating a fault diagnosis model for the capacitor to predict faults according to the first change rule, the second change rule and the third change rule,
generating a first fault diagnosis model according to the first change rule and the third change rule, wherein the first fault diagnosis model is used for predicting a first probability of the capacitor having a fault by collecting the switching times of the capacitor;
generating a second fault diagnosis model according to the first change rule and the second change rule, wherein the second fault diagnosis model is used for predicting a second probability of the capacitor having faults by acquiring the temperature rise speed of the capacitor;
generating a third fault diagnosis model according to the second change rule and the third change rule, wherein the third fault diagnosis model is used for predicting a third probability of the capacitance fault by collecting the switching times and the temperature rise speed of the capacitor;
according to the first probability and/or the second probability and/or the third probability,
and judging whether the capacitor is in fault.
10. The capacitor analysis system according to any one of claims 7-9, wherein:
the capacitor analysis system further comprises a fault positioning module for obtaining a harmonic impedance value of the capacitor at the bus according to the generated harmonic voltage value and the harmonic current value, and positioning the capacitor according to the harmonic impedance value.
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Denomination of invention: A capacitor analysis method and system Effective date of registration: 20230621 Granted publication date: 20230210 Pledgee: Bank of Beijing Limited by Share Ltd. Shanghai branch Pledgor: TIANNA ENERGY TECHNOLOGY (SHANGHAI) CO.,LTD. Registration number: Y2023980044969 |