CN110703015B - Capacitor monitoring method based on differential pressure - Google Patents

Capacitor monitoring method based on differential pressure Download PDF

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CN110703015B
CN110703015B CN201910921759.6A CN201910921759A CN110703015B CN 110703015 B CN110703015 B CN 110703015B CN 201910921759 A CN201910921759 A CN 201910921759A CN 110703015 B CN110703015 B CN 110703015B
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phase
capacitor
differential pressure
jδv
breakdown
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马俊
马启月
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Xi'an Xd Iot Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/10—Measuring sum, difference or ratio

Abstract

The invention relates to the technical field of circuit monitoring, in particular to a capacitor monitoring method based on differential pressure, which utilizes a capacitor device and existing signals protected by the capacitor device to realize high-precision testing and fault positioning of capacitor faults, introduces three-phase line voltage of a system, combines the differential pressure of each phase of capacitor to obtain a judgment state quantity, improves the judgment precision of the faults and obtains fault position information; expressing the system line voltage and the differential pressure in a complex form, and calculating to obtain a discrimination coefficient; can be used to determine that the coefficient is related only to the impedance of the monitored capacitor bank; the method can be used for judging the difference of the judging coefficients at different times; the threshold value which can be used for judging the coefficient is 0.0005 to 1 time of the change rate of the phase capacitance after the single element is broken down; the location where the component breakdown occurs can be determined from the sign of the discrimination coefficient.

Description

Capacitor monitoring method based on differential pressure
Technical Field
The invention relates to the technical field of circuit monitoring, in particular to a capacitor monitoring method based on differential pressure.
Background
At present, the internal protection methods of high-voltage power capacitors are all unbalanced protection, and the monitoring method generally adopts a scheme of monitoring capacitor units one by one, namely monitoring parameters such as voltage, current and temperature of each capacitor and judging whether the capacitor fails, and the method has various defects and mainly comprises the following steps: the number of the capacitor units is too large in one set of capacitor device, and the capacitor units are usually contained in a large number, and according to the voltage grade and the capacity of a transformer substation, the number of the capacitor units contained in one set of capacitor device is about 25 to 50 in a high-voltage transformer substation, and is up to hundreds in an extra-high voltage transformer substation and an extra-high voltage transformer substation. Therefore, each capacitor unit needs to be monitored, related monitoring equipment needs to be installed on all the capacitor units, a communication system and a software platform with large node number are built, and the system is high in difficulty, high in complexity, high in cost and difficult to construct and install. High-voltage capacitors with high test terminal complexity are often mounted on a high-voltage insulating platform, and each capacitor is provided with a monitoring terminal, so that the problems of energy taking, communication, heat dissipation and the like of the terminal need to be solved. Because the voltage difference of tens of kilovolts exists between the insulating platform and the ground, the cable cannot be directly laid from the ground to the insulating platform, the technologies such as local induction energy taking, wireless communication and the like are generally adopted, the capacitor often runs outdoors and is seriously influenced by sunlight, wind, rain and the like, special design needs to be carried out on water resistance, heat dissipation, weather resistance and the like, and the technical complexity of the test terminal is very high due to the factors. Influence on primary wiring parameters such as voltage, current, and temperature are measured for each capacitor, and it is inevitable to install a sensor such as a transformer or a coil at a terminal of the capacitor, which may adversely affect reliability, creepage distance, and mechanical strength of the primary wiring of the capacitor. Due to the fact that the number of the high-voltage power capacitors is large, the technical complexity of the terminal device is high, the overall reliability and the service life of a hardware system are reduced, the design life of the high-voltage power capacitor reaches 20 years to 30 years, and the failure rate is low under normal working conditions. Electronic devices generally have a lifetime of only 3 to 5 years in an outdoor environment and a high failure rate. Therefore, the scheme of monitoring each capacitor may cause the problem that the hardware maintenance workload and the maintenance cost of the monitoring system are larger than those of the capacitor. The existing capacitor protection methods are all unbalanced protection, symmetric faults of a capacitor device are invalid, the monitored data information amount is low, the operation condition of the capacitor cannot be evaluated, and the fault capacitor cannot be positioned. The capacitor may still have serious failures such as unplanned shutdown, explosion and fire, etc., and the maintenance efficiency after trip is too low. For a 35kV high-voltage capacitor device, a Y-shaped wiring with a non-grounded neutral point and differential pressure protection are usually adopted, and the device needs to measure the bus line voltage and the phase current.
Disclosure of Invention
The invention aims to provide a capacitor monitoring method based on differential pressure, which aims to solve the problems that for a 35kV high-voltage capacitor device, Y-shaped wiring with ungrounded neutral points and differential pressure protection are adopted, and the device needs to measure bus line voltage and phase current.
In order to achieve the purpose, the invention provides the following technical scheme:
a differential pressure based capacitor monitoring method, comprising the steps of:
s1: first measuring three-phase differential pressure
Figure GDA0003273962310000021
And three phase line voltage
Figure GDA0003273962310000022
S2: calculating the complex form of the three-phase differential pressureA0+jΔVA0、ΔUB0+jΔVB0、ΔUC0+jΔVC0And converting the three-phase line voltage into a complex form Uab0+jVab0、Ubc0+jVbc0、Uca0+jVca0；
S3: calculating the discrimination coefficient at the moment as TA10、TB10、TC10、TA20、TB20、TC20；
S4: after a period of time delay, the three-phase differential pressure is measured
Figure GDA0003273962310000023
And three phase line voltage
Figure GDA0003273962310000024
Figure GDA0003273962310000025
S5: calculating the complex form of the three-phase differential pressureA1+jΔVA1、ΔUB1+jΔVB1、ΔUC1+jΔVC1And converting the three-phase line voltage into a complex form Uab1+jVab1、Ubc1+jVbc1、Uca1+jVca1；
S6: calculating the discrimination coefficient TA11、TB11、TC11、TA21、TB21、TC21；
S7: calculating the discrimination M according to the discrimination coefficients of the previous and the next timesA、MB、MCAnd setting a judgment threshold value Mth；
S8: if | MA|＞MthThen, it can be determined that phase A occursThe component is broken down if MAGreater than 0, i.e. the breakdown position is CA1If M is presentA< 0, i.e. the breakdown position is CA2(ii) a In the same way, for the B-phase capacitor and the C-phase capacitor, the discrimination coefficients are respectively TB1，TB2And TC1，TC2The judgment amount and the judgment process are the same as those in A.
Preferably, the threshold value M is determinedthIs 0.0005k to 1 k.
Preferably, the differential pressure
Figure GDA0003273962310000026
Is a phase capacitor CA1And CA2Voltage difference of (a), namely:
Figure GDA0003273962310000027
wherein XAIs the impedance of the A-phase capacitor, XBIs the impedance of the B-phase capacitor, XCIs C-phase capacitor impedance, XA1Is CA1Impedance, XA2Is CA2Impedance, and similarly, the phase difference voltage B
Figure GDA0003273962310000031
And difference of voltage from C
Figure GDA0003273962310000032
Preferably, the differential pressure
Figure GDA0003273962310000033
Expressed in complex form as Δ UA1+jΔVA1Differential pressure
Figure GDA0003273962310000034
Is in the form of Δ UB1+jΔVB1Differential pressure
Figure GDA0003273962310000035
Is in the form of Δ UC1+jΔVC1。
Preferably, the system voltage is expressed in complex form as
Figure GDA0003273962310000036
Figure GDA0003273962310000037
Preferably, the a-phase capacitor discrimination coefficient is set to TA1And TA2Then there is
Figure GDA0003273962310000038
Let t0Solution of time to TA10，TA20，t1Solution of time to TA11，TA21If the component breakdown occurs in the phase a capacitor and the capacitance change rate is k, the determination amount is: mA＝TA11-TA10+TA21-TA20。|MA|＞MthThen, it can be determined that the component breakdown occurred in phase A, and if M is detectedAGreater than 0, i.e. the breakdown position is CA1If M is presentA< 0, i.e. the breakdown position is CA2。
Preferably, the discrimination coefficient T of the B-phase capacitor is setB1And TB2Then there is
Figure GDA0003273962310000039
Let t0Solution of time to TB10，TB20，t1Solution of time to TB11，TB21If the element breakdown occurs in the B-phase capacitor and the capacitance change rate is k, the determination amount is: mB＝TB11-TB10+TB21-TB20。|MB|＞MthThen, it can be determined that the component breakdown occurred in phase B, and if M is detectedBGreater than 0, i.e. the breakdown position is CB1If M is presentB< 0, i.e. the breakdown position is CB2。
Preferably, the coefficient of discrimination T of the C-phase capacitor is setC1And TC2Then there is
Figure GDA00032739623100000310
Let t0Solution of time to TC10，TC20，t1Solution of time to TC11，TC21If the C-phase capacitor is subjected to element breakdown and the capacitance change rate is k, the judgment quantity is as follows: mC＝TC11-TC10+TC21-TC20。|MC|＞MthThen, it can be determined that the component breakdown occurred in the C phase, and if M is detectedCGreater than 0, i.e. the breakdown position is CC1If M is presentC< 0, i.e. the breakdown position is CC2。
Compared with the prior art, the invention has the beneficial effects that:
1. the capacitor monitoring method based on the differential pressure realizes the fault monitoring and fault positioning of the high-voltage capacitor device with a simple system structure, lower cost and higher precision.
2. Compared with the traditional differential pressure protection, the capacitor monitoring method based on the differential pressure eliminates the interference caused by the voltage fluctuation of the system, so that the judgment precision of the fault can be improved, the balance fault can be effectively monitored, and the fault position information can be obtained.
3. Compared with a method for monitoring the capacitor units one by one, the capacitor monitoring method based on the differential pressure does not affect primary equipment, does not increase sensors, and is simple in structure, high in reliability and low in cost.
Drawings
FIG. 1 is a schematic flow chart of the steps of the present invention;
FIG. 2 is a schematic of the computational flow of the present invention;
fig. 3 is a schematic diagram of the wiring principle of the capacitor device and differential pressure protection of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The wiring principle of the capacitor device and the differential pressure protection of the present embodiment is shown in fig. 3, and the capacitor monitoring method based on differential pressure, as shown in fig. 1 and 2, includes the following steps:
s1: first measuring three-phase differential pressure
Figure GDA0003273962310000041
And three phase line voltage
Figure GDA0003273962310000042
S2: calculating the complex form of the three-phase differential pressureA0+jΔVA0、ΔUB0+jΔVB0、ΔUC0+jΔVC0And converting the three-phase line voltage into a complex form Uab0+jVab0、Ubc0+jVbc0、Uca0+jVca0；
S3: calculating the discrimination coefficient at the moment as TA10、TB10、TC10、TA20、TB20、TC20；
S4: after a period of time delay, the three-phase differential pressure is measured
Figure GDA0003273962310000043
And three phase line voltage
Figure GDA0003273962310000044
Figure GDA0003273962310000051
S5: calculating the complex form of the three-phase differential pressureA1+jΔVA1、ΔUB1+jΔVB1、ΔUC1+jΔVC1And converting the three-phase line voltage into a complex form Uab1+jVab1、Ubc1+jVbc1、Uca1+jVca1；
S6: calculating the discrimination coefficient TA11、TB11、TC11、TA21、TB21、TC21；
S7: calculating the discrimination M according to the discrimination coefficients of the previous and the next timesA、MB、MCAnd setting a judgment threshold value Mth；
S8: if | MA|＞MthThen, it can be determined that the component breakdown occurred in phase A, and if M is detectedAGreater than 0, i.e. the breakdown position is CA1If M is presentA< 0, i.e. the breakdown position is CA 2; in the same way, for the B-phase capacitor and the C-phase capacitor, the discrimination coefficients are respectively TB1，TB2And TC1， TC2The judgment amount and the judgment process are the same as those in A.
Further, the threshold M is judgedthThe value of (a) is 0.0005k to 1k, and the threshold value of the discrimination coefficient is 0.0005 to 1 time of the change rate of the phase capacitance after the single element is broken down.
It is worth to say that the differential pressure
Figure GDA0003273962310000052
Is a phase capacitor CA1And CA2Voltage difference of (a), namely:
Figure GDA0003273962310000053
wherein XAIs the impedance of the A-phase capacitor, XBIs the impedance of the B-phase capacitor, XCIs C-phase capacitor impedance, XA1Is CA1Impedance, XA2Is CA2Impedance, likewise yielding a differential pressure
Figure GDA0003273962310000054
And differential pressure
Figure GDA0003273962310000055
Specifically, differential pressure
Figure GDA0003273962310000056
Expressed in complex formIs Delta UA1+jΔVA1Differential pressure
Figure GDA0003273962310000057
Is in the form of Δ UB1+jΔVB1Differential pressure
Figure GDA0003273962310000058
Is in the form of Δ UC1+jΔVC1。
In addition, the system voltage is expressed in complex form as
Figure GDA0003273962310000059
In addition, let the A-phase capacitor discrimination coefficient be TA1And TA2Then there is
Figure GDA00032739623100000510
Let t0Solution of time to TA10，TA20，t1Solution of time to TA11，TA21If the component breakdown occurs in the phase a capacitor and the capacitance change rate is k, the determination amount is: mA＝TA11-TA10+TA21-TA20。
Setting the discrimination coefficient T of the B-phase capacitorB1And TB2Then there is
Figure GDA00032739623100000511
Let t0Solution of time to TB10，TB20，t1Solution of time to TB11，TB21If the element breakdown occurs in the B-phase capacitor and the capacitance change rate is k, the determination amount is: mB＝TB11-TB10+TB21-TB20。
Setting the discrimination coefficient T of the C-phase capacitorC1And TC2Then there is
Figure GDA0003273962310000061
Let t0Solution of time to TC10，TC20，t1Time of dayIs solved as TC11，TC21If the C-phase capacitor is subjected to element breakdown and the capacitance change rate is k, the judgment quantity is as follows: mC＝TC11-TC10+TC21-TC20。
The invention realizes the high-precision test and fault location of capacitor faults by using the capacitor device and the existing signals protected by the capacitor device, introduces the three-phase line voltage of a system, combines the differential pressure of each phase of capacitor to obtain the judgment state quantity, improves the judgment precision of the faults and obtains the fault position information; expressing the system line voltage and the differential pressure in a complex form, and calculating to obtain a discrimination coefficient; the discrimination coefficient is only related to the impedance of the monitored capacitor bank; the judgment quantity is the difference of the judgment coefficients at different times; the threshold value of the discrimination coefficient is 0.0005 to 1 time of the phase capacity change rate after the single element is broken down; and determining the position of the component breakdown according to the sign of the discrimination coefficient.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (4)

1. A capacitor monitoring method based on differential pressure is characterized in that: the method comprises the following steps:
s1: first measuring three-phase differential pressure
Figure FDA0003273962300000011
And three phase line voltage
Figure FDA0003273962300000012
S2: calculating the complex form of the three-phase differential pressureA0+jΔVA0、ΔUB0+jΔVB0、ΔUC0+jΔVC0And converting the three-phase line voltage into a complex form Uab0+jVab0、Ubc0+jVbc0、Uca0+jVca0；
S3: calculating t0The time discrimination coefficient is TA10、TB10、TC10、TA20、TB20、TC20；
S4: after a period of time delay, the three-phase differential pressure is measured
Figure FDA0003273962300000013
And three phase line voltage
Figure FDA0003273962300000014
Figure FDA0003273962300000015
S5: calculating the complex form of the three-phase differential pressureA1+jΔVA1、ΔUB1+jΔVB1、ΔUC1+jΔVC1And converting the three-phase line voltage into a complex form Uab1+jVab1、Ubc1+jVbc1、Uca1+jVca1；
S6: calculating the discrimination coefficient TA11、TB11、TC11、TA21、TB21、TC21；
S7: calculating the discrimination M according to the discrimination coefficients of the previous and the next timesA、MB、MCAnd setting a judgment threshold value MthLet the A-phase capacitor discrimination coefficient be TA1And TA2Then there is
Figure FDA0003273962300000016
Let t0Solution of time to TA10，TA20，t1Solution of time to TA11，TA21If the component breakdown occurs in the phase a capacitor and the capacitance change rate is k, the determination amount is: mA＝TA11-TA10+TA21-TA20If | MA|>MthThen, it can be determined that the component breakdown occurred in phase A, and if M is detectedA>0, i.e. breakdown position is CA1If M is presentA<0, i.e. breakdown position is CA2(ii) a Setting the discrimination coefficient T of the B-phase capacitorB1And TB2Then there is
Figure FDA0003273962300000017
Let t0Solution of time to TB10，TB20，t1Solution of time to TB11，TB21If the element breakdown occurs in the B-phase capacitor and the capacitance change rate is k, the determination amount is: mB＝TB11-TB10+TB21-TB20If | MB|>MthThen, it can be determined that the component breakdown occurred in phase B, and if M is detectedB>0, i.e. breakdown position is CB1If M is presentB<0, i.e. breakdown position is CB2(ii) a Setting the discrimination coefficient T of the C-phase capacitorC1And TC2Then there is
Figure FDA0003273962300000018
Let t0Solution of time to TC10，TC20，t1Solution of time to TC11，TC21If the C-phase capacitor is subjected to element breakdown and the capacitance change rate is k, the judgment quantity is as follows: mC＝TC11-TC10+TC21-TC20If | MC|>MthThen, it can be determined that the component breakdown occurred in the C phase, and if M is detectedC>0, i.e. breakdown position is CC1If M is presentC<0, i.e. breakdown position is CC2。
2. The differential pressure based capacitor monitoring method of claim 1, wherein: judgment threshold value MthIs 0.0005k to 1 k.
3. The differential pressure based of claim 1The capacitor monitoring method is characterized in that: three-phase differential pressure
Figure FDA0003273962300000024
Is in the form of Δ UA1+jΔVA1Differential pressure of three phases
Figure FDA0003273962300000021
Is in the form of Δ UB1+jΔVB1Differential pressure of three phases
Figure FDA0003273962300000022
Is in the form of Δ UC1+jΔVC1。
4. The differential pressure based capacitor monitoring method of claim 1, wherein: the system voltage is expressed in complex form as
Figure FDA0003273962300000023
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CN1531159A (en) * 2003-03-14 2004-09-22 福建省电力勘测设计院 Differential pressure regulating protector of resistor set
CN103499728A (en) * 2013-07-19 2014-01-08 上海磁浮交通工程技术研究中心 Method and system for detecting voltage unbalance of series capacitor bank
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