CN109596894A - Ac capacitor on-line monitoring method and device - Google Patents
Ac capacitor on-line monitoring method and device Download PDFInfo
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- CN109596894A CN109596894A CN201910001850.6A CN201910001850A CN109596894A CN 109596894 A CN109596894 A CN 109596894A CN 201910001850 A CN201910001850 A CN 201910001850A CN 109596894 A CN109596894 A CN 109596894A
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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
Abstract
The present invention is suitable for technical field of electricity, a kind of ac capacitor on-line monitoring method and device provided by the invention, which comprises obtain inductor current value, grid-connected current value, grid-connected voltage value and the capacitor input voltage value of current transformer；Ac capacitor current value is obtained according to the inductor current value, grid-connected current value；Ac capacitor voltage value is obtained according to the grid-connected voltage value and capacitor input voltage value；According to the ac capacitor current value and the ac capacitor voltage value, the actual capacity value of the ac capacitor is determined；Ac capacitor is monitored according to the actual capacity value of the ac capacitor and raw capacity value, the Trueattenuation situation of ac capacitor can be obtained.
Description
Technical field
The invention belongs to technical field of electricity more particularly to a kind of ac capacitor on-line monitoring methods and device.
Background technique
With the fast development of industry, electrical equipment gradually increases, and wants to the capacity of current transformer, efficiency, reliability
Ask higher and higher, single converter cell autonomous working has been unable to satisfy demand, and current transformer parallel operation is held as expansion system
A kind of important channel of amount.The projected life of grid-connected converter, the ac capacitor in current transformer was when long usually at 10 years or more
Between run after, the capacitance of capacitor can gradually decay, and have larger impact to the reliability and performance indicator of grid-connected converter.
Currently, the method that traditional ac capacitor to grid-connected converter is monitored is to monitor the operation of ac capacitor
Time, reaching the regular hour is to replace to ac capacitor.But due to grid-connected converter actual operating mode, scheduling and
The attenuation of the influence of the factors such as environment, each ac capacitor is different, and certain ac capacitor decaying are very fast, does not replace in time
It will cause the reliability decrease of grid-connected converter complete machine work, and the decaying of other ac capacitors is slower, replaces capacitor meeting ahead of time
It results in waste of resources.
Summary of the invention
In view of this, being able to solve existing the embodiment of the invention provides a kind of ac capacitor on-line monitoring method and device
There is the attenuation of each ac capacitor existing for technology different, certain ac capacitor decaying are very fast, cause without replacement in time
The reliability decrease of grid-connected converter complete machine work, and the decaying of other ac capacitors is slower, replaces capacitor ahead of time and causes resource
The problem of waste.
The embodiment of the present invention in a first aspect, providing a kind of ac capacitor on-line monitoring method, comprising:
Obtain inductor current value, grid-connected current value, grid-connected voltage value and the capacitor input voltage value of current transformer；
Ac capacitor current value is obtained according to the inductor current value, grid-connected current value；
Ac capacitor voltage value is obtained according to the grid-connected voltage value and capacitor input voltage value；
According to the ac capacitor current value and the ac capacitor voltage value, the actual capacity of the ac capacitor is determined
Value；
Ac capacitor is monitored according to the actual capacity value of the ac capacitor and raw capacity value.
The second aspect of the embodiment of the present invention provides a kind of ac capacitor on-Line Monitor Device, comprising:
Parameter acquisition module, inductor current value, grid-connected current value, grid-connected voltage value and the capacitor for obtaining current transformer are defeated
Enter voltage value；
Current value processing module, for obtaining ac capacitor current value according to the inductor current value, grid-connected current value；
Voltage value processing module, for obtaining ac capacitor voltage according to the grid-connected voltage value and capacitor input voltage value
Value；
Actual capacity value determining module is used for according to the ac capacitor current value and the ac capacitor voltage value, really
The actual capacity value of the fixed ac capacitor；
The third aspect of the embodiment of the present invention, provides a kind of terminal device, including memory, processor and is stored in
In the memory and the computer program that can run on the processor, when the processor executes the computer program
The step of realizing above-mentioned ac capacitor on-line monitoring method.
The fourth aspect of the embodiment of the present invention, provides a kind of computer readable storage medium, described computer-readable to deposit
Storage media is stored with computer program, and the computer program realizes above-mentioned ac capacitor on-line monitoring when being executed by processor
The step of method.
The beneficial effect of the embodiment of the present invention compared with prior art is: the embodiment of the present invention is first according to inductive current
Value, grid-connected current value, obtain ac capacitor current value, further according to grid-connected voltage value and capacitor input voltage value, obtain alternating current
Hold voltage value and determines the reality of the ac capacitor then according to the ac capacitor current value and the ac capacitor voltage value
Border capability value is finally monitored ac capacitor according to the actual capacity value of ac capacitor and raw capacity value, can obtain
The Trueattenuation situation of ac capacitor is monitored, rather than is monitored according to the runing time of ac capacitor, is replaced in time
Faster ac capacitor decay to guarantee the reliability of current transformer complete machine work, retains and decays slower ac capacitor to save money
Source.
Detailed description of the invention
It to describe the technical solutions in the embodiments of the present invention more clearly, below will be to embodiment or description of the prior art
Needed in attached drawing be briefly described, it should be apparent that, the accompanying drawings in the following description is only of the invention some
Embodiment for those of ordinary skill in the art without any creative labor, can also be according to these
Attached drawing obtains other attached drawings.
Fig. 1 is a kind of grid-connected converter system structure diagram that one embodiment of the invention provides；
Fig. 2 is a kind of flow diagram for ac capacitor on-line monitoring method that one embodiment of the invention provides；
Fig. 3 be another embodiment of the present invention provides a kind of ac capacitor on-line monitoring method flow diagram；
Fig. 4 is a kind of flow diagram for ac capacitor on-line monitoring method that yet another embodiment of the invention provides；
Fig. 5 is a kind of structural block diagram for ac capacitor on-Line Monitor Device that one embodiment of the invention provides；
Fig. 6 is a kind of schematic block diagram of the terminal device for ac capacitor on-line monitoring that one embodiment of the invention provides.
Specific embodiment
In being described below, for illustration and not for limitation, the tool of such as particular system structure, technology etc is proposed
Body details, to understand thoroughly the embodiment of the present invention.However, it will be clear to one skilled in the art that there is no these specific
The present invention also may be implemented in the other embodiments of details.In other situations, it omits to well-known system, device, electricity
The detailed description of road and method, in case unnecessary details interferes description of the invention.
In order to illustrate technical solutions according to the invention, the following is a description of specific embodiments.
With reference to Fig. 1, Fig. 1 is a kind of grid-connected converter system structure diagram that one embodiment of the invention provides.Wherein, and
Net current transformer is made of three-phase half-bridge plus LC low-pass filter, wherein ac capacitor Ca、CbAnd Cc, before and after ac capacitor
Electric current is respectively inductive current iLa、iLbAnd iLcWith grid-connected current iga、igbAnd igc。Uga、UgbAnd UgcFor grid-connected voltage, VxFor electricity
Hold input voltage.
With reference to Fig. 2, Fig. 2 is a kind of process signal for ac capacitor on-line monitoring method that one embodiment of the invention provides
Figure.This method can be applied to the controller installed on current transformer, such as single-chip microcontroller, and details are as follows for the process of the present embodiment:
S201: inductor current value, grid-connected current value, grid-connected voltage value and the capacitor input voltage value of current transformer are obtained.
In the present embodiment, current transformer is grid-connected converter.Inductor current value, grid-connected current value, grid-connected voltage value and electricity
Hold input voltage value is indicated with three-phase static coordinate system.
Specifically, the three-phase electricity flow valuve that inductance output end can be obtained by current sensor, obtains the inductance of current transformer
Current value.By obtaining the three-phase electricity flow valuve of capacitor output end, the grid-connected current value of current transformer is obtained.Pass through voltage measuring apparatus
The three-phase voltage value for obtaining capacitor output end, obtains the grid-connected voltage value of current transformer.By the three-phase electricity for obtaining capacitor input terminal
Pressure is worth to obtain the capacitor input voltage value of current transformer.
S202: ac capacitor current value is obtained according to inductor current value, grid-connected current value.
In the present embodiment, it is poor inductor current value and grid-connected current value can be made, and ac capacitor current value is calculated.
S203: ac capacitor voltage value is obtained according to grid-connected voltage value and capacitor input voltage value.
In the present embodiment, it is poor grid-connected voltage value and capacitor input voltage value can be made, to alternating current is calculated
Hold voltage value.
S204: according to the ac capacitor current value and the ac capacitor voltage value, the reality of the ac capacitor is determined
Border capability value.
In the present embodiment, ac capacitor current value and ac capacitor voltage value will can be imported capacitance current differential
Formula calculates the actual capacity value that capacitance current differential formulas determines the ac capacitor.
S205: ac capacitor is monitored according to the actual capacity value of ac capacitor and raw capacity value.
In the present embodiment, raw capacity value can be obtained from the specifications of capacitor.
As can be seen from the above description, the actual capacity value and raw capacity value by ac capacitor supervise ac capacitor
It surveys, the Trueattenuation situation that can obtain ac capacitor is monitored, rather than is supervised according to the runing time of ac capacitor
It surveys, replacement in time decays faster ac capacitor to guarantee the reliability of current transformer complete machine work, retains the slower exchange that decays
Capacitor is to economize on resources.
With reference to Fig. 3, Fig. 3 be another embodiment of the present invention provides a kind of ac capacitor on-line monitoring method process signal
Figure.On the basis of the above embodiments, step S204 includes:
S301: by ac capacitor current value and ac capacitor voltage value, capacitance current differential formulas is imported.
In the present embodiment, capacitance current differential formulasC is capacitor in formula, and U is capacitance voltage, and i is capacitor
Electric current, t are the time.
S302: by capacitance current differential formulas ac capacitor current value and ac capacitor voltage value sat by three phase static
Mark system is converted to two-phase rotating coordinate system, calculates capacitance current differential formulas and obtains the actual capacity value of ac capacitor.
In the present embodiment, the actual capacity of ac capacitor is obtained by carrying out integral operation to capacitance current differential formulas
Value.
In one embodiment of the invention, it is calculated in step S202 according to the inductor current value, grid-connected current value
To ac capacitor current value are as follows:
In formula (1), iCa、iCbAnd iCcFor the ac capacitor current value of three-phase static coordinate system, iLa、iLbAnd iLcFor three-phase
The inductor current value of rest frame, iga、igbAnd igcFor the grid-connected current value of three-phase static coordinate system.
According to the grid-connected voltage value and capacitor input voltage value in step S203, ac capacitor voltage value is calculated
Are as follows:
In formula (2), UCa、UCbAnd UCcFor the ac capacitor voltage value of three-phase static coordinate system, Uga、UgbAnd UgcFor three-phase
The grid-connected voltage value of rest frame, VxWhen for ac capacitor star connection, neutral point voltage value.
In one embodiment of the invention, by the ac capacitor current value and ac capacitor electricity in step S301
Pressure value imports capacitance current differential formulas are as follows:
In formula (3), wherein C is the capacitance of ac capacitor.
In one embodiment of the invention, in step S302, by the ac capacitor in the capacitance current differential formulas
Current value is converted to two-phase rotating coordinate system by three-phase static coordinate system are as follows:
In formula (4), iLqAnd iLdFor the inductor current value of two-phase rotating coordinate system, igqAnd igdFor two-phase rotating coordinate system
Grid-connected current value, C3s/2rThe transformation matrix of two-phase rotating coordinate system is converted to for three-phase static coordinate system, wherein C3s/2rValue
It is as follows,
The ac capacitor voltage value in the capacitance current differential formulas is converted to two by three-phase static coordinate system
Cordic phase rotator system are as follows:
In formula (5), UgqAnd UgdFor the ac capacitor voltage value of two-phase rotating coordinate system；
Formula (4) and (5) are imported in formula (3), obtained
Wherein
In formula (6), S is Laplace operator.
If the positive-sequence component of grid-connected voltage isIt is with negative sequence componentThen grid-connected voltage value are as follows:
In formula, Uga、UgbAnd UgcFor the three-phase voltage value of grid-connected voltage value, ω is the angle speed that current transformer exports grid-connected voltage
Degree；
By formula (6) and (7), the actual capacity value of the two-phase rotating coordinate system of ac capacitor is obtained
Wherein
In another embodiment of the present invention, it can incite somebody to actionIt is quiet that three-phase is transformed to by two-phase rotating coordinate system
Only coordinate system obtainsIts transformation for mula is C3s/2r -1, obtain the quiet actual capacity value of the three-phase of ac capacitor.
As can be seen from the above description, the reason of being coordinately transformed is ac capacitor current value and the ac capacitor voltage value
It is of ac, after ac capacitor current value and the ac capacitor voltage value can be converted to DC quantity decoupling after coordinate transform
Closed-loop control is carried out, the calculating of capacitor's capacity, which is placed on two-phase rotating coordinate system, can simplify calculating process.
With reference to Fig. 4, Fig. 4 is a kind of process signal for ac capacitor on-line monitoring method that yet another embodiment of the invention provides
Figure.On the basis of the above embodiments, specifically details are as follows by step S205:
S401: it is poor that actual capacity value and the raw capacity value prestored are made, and obtains the pad value of ac capacitor.
In the present embodiment, the raw capacity value prestored can be obtained from the specifications of capacitor itself.
S402: judge whether pad value has exceeded preset drop threshold.
In the present embodiment, preset drop threshold can be determined according to time situation, can also be according to old in complete machine
Change experiment and practical measuring and calculating is carried out to capacitance/service life.
S403: if pad value has exceeded preset drop threshold, alarm prompt is sent to alarm.
In the present embodiment, it if pad value is without departing from preset drop threshold, sends and retains prompt information to display
Terminal reminds user that can continue to use.
It should be understood that the size of the serial number of each step is not meant that the order of the execution order in above-described embodiment, each process
Execution sequence should be determined by its function and internal logic, the implementation process without coping with the embodiment of the present invention constitutes any limit
It is fixed.
Corresponding to the ac capacitor on-line monitoring method of foregoing embodiments, Fig. 5 is one kind that one embodiment of the invention provides
The structural block diagram of ac capacitor on-Line Monitor Device, for ease of description, only parts related to embodiments of the present invention are shown.
Referring to Fig. 5, which includes: parameter acquisition module 501, current value processing module 502, voltage value processing module 503, practical appearance
Magnitude determining module 504 and ac capacitor monitoring modular 505.
Wherein, parameter acquisition module 501, for obtaining inductor current value, the grid-connected current value, grid-connected voltage value of current transformer
With capacitor input voltage value；
Current value processing module 502, for obtaining ac capacitor electric current according to the inductor current value, grid-connected current value
Value；
Voltage value processing module 503, for obtaining ac capacitor according to the grid-connected voltage value and capacitor input voltage value
Voltage value；
Actual capacity value determining module 504 is used for according to the ac capacitor current value and the ac capacitor voltage value,
Determine the actual capacity value of the ac capacitor；
Ac capacitor monitoring modular 505, for the actual capacity value and raw capacity value according to the ac capacitor to friendship
Galvanic electricity appearance is monitored.
As can be seen from the above description, the actual capacity value and raw capacity value by ac capacitor supervise ac capacitor
It surveys, the Trueattenuation situation that can obtain ac capacitor is monitored, rather than is supervised according to the runing time of ac capacitor
It surveys, replacement in time decays faster ac capacitor to guarantee the reliability of current transformer complete machine work, retains the slower exchange that decays
Capacitor is to economize on resources.
With reference to Fig. 5, in one embodiment of the invention, the actual capacity value determining module 504 is specifically used for institute
Ac capacitor current value and the ac capacitor voltage value are stated, capacitance current differential formulas is imported, by the capacitance current differential
Ac capacitor current value and the ac capacitor voltage value in formula are converted to two cordic phase rotators by three-phase static coordinate system
System calculates capacitance current differential formulas and obtains the actual capacity value of ac capacitor.
With reference to Fig. 5, in one embodiment of the invention, the current value processing module 502, for according to the inductance
Current value, grid-connected current value to ac capacitor current value are as follows:
In formula (1), iCa、iCbAnd iCcFor the ac capacitor current value of three-phase static coordinate system, iLa、iLbAnd iLcFor three-phase
The inductor current value of rest frame, iga、igbAnd igcFor the grid-connected current value of three-phase static coordinate system；
The voltage value processing module 503, for being exchanged according to the grid-connected voltage value with capacitor input voltage value
Capacitance voltage value are as follows:
In formula (2), UCa、UCbAnd UCcFor the ac capacitor voltage value of three-phase static coordinate system, Uga、UgbAnd UgcFor three-phase
The grid-connected voltage value of rest frame, VxWhen for ac capacitor star connection, neutral point voltage value.
With reference to Fig. 5, in one embodiment of the invention, the actual capacity value determining module 504, for described by institute
Ac capacitor current value and the ac capacitor voltage value are stated, capacitance current differential formulas is imported are as follows:
In formula (3), wherein C is the capacitance of ac capacitor.
The actual capacity value determining module 504, for the ac capacitor by the capacitance current differential formulas
Current value and the ac capacitor voltage value are converted to two-phase rotating coordinate system by three-phase static coordinate system, and it is micro- to calculate capacitance current
The actual capacity value that point formula obtains ac capacitor includes:
Ac capacitor current value in the capacitance current differential formulas is converted into two-phase rotation by three-phase static coordinate system
Turn coordinate system are as follows:
In formula (4), iLqAnd iLdFor the inductor current value of two-phase rotating coordinate system, igqAnd igdFor two-phase rotating coordinate system
Grid-connected current value, C3s/2rThe transformation matrix of two-phase rotating coordinate system is converted to for three-phase static coordinate system, wherein C3s/2rValue
It is as follows,
The ac capacitor voltage value in the capacitance current differential formulas is converted to two by three-phase static coordinate system
Cordic phase rotator system are as follows:
In formula (5), UgqAnd UgdFor the ac capacitor voltage value of two-phase rotating coordinate system；
Formula (4) and (5) are imported in formula (3), obtained
Wherein
In formula (6), s is Laplace operator.
If the positive-sequence component of grid-connected voltage isIt is with negative sequence componentThen grid-connected voltage value are as follows:
In formula, Uga、UgbAnd UgcFor the three-phase voltage value of grid-connected voltage value, ω is the angle speed that current transformer exports grid-connected voltage
Degree；
By formula (6) and (7), the actual capacity value of the two-phase rotating coordinate system of ac capacitor is obtained
Wherein
With reference to Fig. 5, in one embodiment of the invention, the ac capacitor monitoring modular 505, being specifically used for will be practical
It is poor that capability value is made with the raw capacity value prestored, obtains the pad value of ac capacitor, it is pre- to judge whether the pad value has exceeded
If drop threshold send alarm prompt to alarm if pad value has exceeded preset drop threshold.
Referring to Fig. 6, Fig. 6 is a kind of signal of the terminal device for ac capacitor on-line monitoring that one embodiment of the invention provides
Block diagram.Terminal 600 in the present embodiment as shown in FIG. 6 may include: one or more processors 601, one or more defeated
Enter equipment 602, one or more then output equipments 603 and one or more memories 604.Above-mentioned processor 601, input equipment
602, then output equipment 603 and memory 604 by communication bus 605 complete mutual communication.Memory 604 is for storing
Computer program, the computer program include program instruction.The program that processor 601 is used to execute the storage of memory 604 refers to
It enables.Wherein, processor 601 is configured for that described program instruction execution or less is called to operate each mould in above-mentioned each Installation practice
Block/unit function, such as the function of module 501 to 505 shown in Fig. 5.
It should be appreciated that in embodiments of the present invention, alleged processor 601 can be central processing unit (Central
Processing Unit, CPU), which can also be other general processors, digital signal processor (Digital
Signal Processor, DSP), specific integrated circuit (Application Specific Integrated Circuit,
ASIC), ready-made programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic
Device, discrete gate or transistor logic, discrete hardware components etc..General processor can be microprocessor or this at
Reason device is also possible to any conventional processor etc..
Input equipment 602 may include that Trackpad, fingerprint adopt sensor (for acquiring the finger print information and fingerprint of user
Directional information), microphone etc., output equipment 603 may include display (LCD etc.), loudspeaker etc..
The memory 604 may include read-only memory and random access memory, and to processor 601 provide instruction and
Data.The a part of of memory 604 can also include nonvolatile RAM.For example, memory 604 can also be deposited
Store up the information of device type.
In the specific implementation, processor 601 described in the embodiment of the present invention, input equipment 602, output equipment 603 can
Implementation described in the first embodiment and second embodiment of service request method provided in an embodiment of the present invention is executed,
Also the implementation of terminal described in the embodiment of the present invention can be performed, details are not described herein.
A kind of computer readable storage medium, the computer-readable storage medium are provided in another embodiment of the invention
Matter is stored with computer program, and the computer program includes program instruction, realization when described program instruction is executed by processor
All or part of the process in above-described embodiment method can also instruct relevant hardware to complete by computer program,
The computer program can be stored in a computer readable storage medium, the computer program when being executed by processor,
The step of above-mentioned each embodiment of the method can be achieved.Wherein, the computer program includes computer program code, the meter
Calculation machine program code can be source code form, object identification code form, executable file or certain intermediate forms etc..The calculating
Machine readable medium may include: any entity or device, recording medium, USB flash disk, the shifting that can carry the computer program code
Dynamic hard disk, magnetic disk, CD, computer storage, read-only memory (Read-Only Memory, ROM), random access memory
(Random Access Memory, RAM), electric carrier signal, telecommunication signal and software distribution medium etc..It needs to illustrate
It is that the content that the computer-readable medium includes can be fitted according to the requirement made laws in jurisdiction with patent practice
When increase and decrease, such as in certain jurisdictions, according to legislation and patent practice, computer-readable medium do not include be electric carrier wave
Signal and telecommunication signal.
The computer readable storage medium can be the internal storage unit of terminal described in aforementioned any embodiment, example
Such as the hard disk or memory of terminal.The computer readable storage medium is also possible to the External memory equipment of the terminal, such as
The plug-in type hard disk being equipped in the terminal, intelligent memory card (Smart Media Card, SMC), secure digital (SD,
Secure Digital) card, flash card (Flash Card) etc..Further, the computer readable storage medium can be with
Both including the terminal internal storage unit and also including External memory equipment.The computer readable storage medium is for storing
Other programs and data needed for the computer program and the terminal.The computer readable storage medium can be also used for
Temporarily store the data that has exported or will export.
Those of ordinary skill in the art may be aware that list described in conjunction with the examples disclosed in the embodiments of the present disclosure
Member and algorithm steps, can be realized with electronic hardware, computer software, or a combination of the two, in order to clearly demonstrate hardware
With the interchangeability of software, each exemplary composition and step are generally described according to function in the above description.This
A little functions are implemented in hardware or software actually, the specific application and design constraint depending on technical solution.Specially
Industry technical staff can use different methods to achieve the described function each specific application, but this realization is not
It is considered as beyond the scope of this invention.
It is apparent to those skilled in the art that for convenience of description and succinctly, the end of foregoing description
The specific work process at end and unit, can refer to corresponding processes in the foregoing method embodiment, details are not described herein.
In several embodiments provided herein, it should be understood that disclosed terminal and method can pass through it
Its mode is realized.For example, the apparatus embodiments described above are merely exemplary, for example, the division of the unit, only
Only a kind of logical function partition, there may be another division manner in actual implementation, such as multiple units or components can be tied
Another system is closed or is desirably integrated into, or some features can be ignored or not executed.In addition, shown or discussed phase
Mutually between coupling, direct-coupling or communication connection can be through some interfaces, the INDIRECT COUPLING or communication of device or unit
Connection is also possible to electricity, mechanical or other form connections.
The unit as illustrated by the separation member may or may not be physically separated, aobvious as unit
The component shown may or may not be physical unit, it can and it is in one place, or may be distributed over multiple
In network unit.Some or all of unit therein can be selected to realize the embodiment of the present invention according to the actual needs
Purpose.
It, can also be in addition, the functional units in various embodiments of the present invention may be integrated into one processing unit
It is that each unit physically exists alone, is also possible to two or more units and is integrated in one unit.It is above-mentioned integrated
Unit both can take the form of hardware realization, can also realize in the form of software functional units.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can readily occur in various equivalent modifications or replace
It changes, these modifications or substitutions should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with right
It is required that protection scope subject to.
Claims (10)
1. a kind of ac capacitor on-line monitoring method characterized by comprising
Obtain inductor current value, grid-connected current value, grid-connected voltage value and the capacitor input voltage value of current transformer；
Ac capacitor current value is obtained according to the inductor current value, grid-connected current value；
Ac capacitor voltage value is obtained according to the grid-connected voltage value and capacitor input voltage value；
According to the ac capacitor current value and the ac capacitor voltage value, the actual capacity value of the ac capacitor is determined；
Ac capacitor is monitored according to the actual capacity value of the ac capacitor and raw capacity value.
2. ac capacitor on-line monitoring method according to claim 1, which is characterized in that described according to the ac capacitor
Current value and the ac capacitor voltage value, determine the actual capacity value of the ac capacitor, comprising:
By the ac capacitor current value and the ac capacitor voltage value, capacitance current differential formulas is imported；
By in the capacitance current differential formulas ac capacitor current value and the ac capacitor voltage value sat by three phase static
Mark system is converted to two-phase rotating coordinate system, calculates capacitance current differential formulas and obtains the actual capacity value of ac capacitor.
3. ac capacitor on-line monitoring method according to claim 1 or 2, which is characterized in that described according to the inductance
Current value, grid-connected current value, are calculated ac capacitor current value are as follows:
In formula (1), iCa、icbAnd iCcFor the ac capacitor current value of three-phase static coordinate system, iLa、iLbAnd iLcFor three phase static
The inductor current value of coordinate system, iga、igbAnd igcFor the grid-connected current value of three-phase static coordinate system；
It is described according to the grid-connected voltage value and capacitor input voltage value, ac capacitor voltage value is calculated are as follows:
In formula (2), UCa、UCbAnd UCcFor the ac capacitor voltage value of three-phase static coordinate system, Uga、UgbAnd UgcFor three phase static
The grid-connected voltage value of coordinate system, VxWhen for ac capacitor star connection, neutral point voltage value.
4. ac capacitor on-line monitoring method according to claim 3, which is characterized in that described by the ac capacitor electricity
Flow valuve and the ac capacitor voltage value import capacitance current differential formulas are as follows:
In formula (3), wherein C is the capacitance of ac capacitor.
5. ac capacitor on-line monitoring method according to claim 4, which is characterized in that described that the capacitance current is micro-
The ac capacitor current value and the ac capacitor voltage value divided in formula is converted to two-phase rotation by three-phase static coordinate system and sits
Mark system calculates capacitance current differential formulas and obtains the actual capacity value of ac capacitor, comprising:
Ac capacitor current value in the capacitance current differential formulas is converted to two-phase rotation by three-phase static coordinate system to sit
Mark system are as follows:
In formula (4), iLqAnd iLdFor the inductor current value of two-phase rotating coordinate system, igqAnd igdFor two-phase rotating coordinate system and
Net current value, C3s/2rThe transformation matrix of two-phase rotating coordinate system is converted to for three-phase static coordinate system, wherein C3s/2rValue is such as
Under,
The ac capacitor voltage value in the capacitance current differential formulas is converted into two-phase rotation by three-phase static coordinate system
Turn coordinate system are as follows:
In formula (5), UgqAnd UgdFor the ac capacitor voltage value of two-phase rotating coordinate system；
Formula (4) and (5) are imported in formula (3), obtained
Wherein
In formula (6), s is Laplace operator.
If the positive-sequence component of grid-connected voltage isIt is with negative sequence componentThen grid-connected voltage value are as follows:
In formula, Uga、UgbAnd UgcFor the three-phase voltage value of grid-connected voltage value, ω is the angular speed that current transformer exports grid-connected voltage；
By formula (6) and (7), the actual capacity value of the two-phase rotating coordinate system of ac capacitor is obtained
Wherein。
6. ac capacitor on-line monitoring method according to claim 1-5, which is characterized in that described according to
The actual capacity value and raw capacity value of ac capacitor are monitored ac capacitor, comprising:
It is poor that actual capacity value and the raw capacity value prestored are made, and obtains the pad value of ac capacitor；
Judge whether the pad value exceeds preset drop threshold；
If pad value exceeds preset drop threshold, alarm prompt is sent to alarm.
7. a kind of ac capacitor on-Line Monitor Device characterized by comprising
Parameter acquisition module, for obtaining inductor current value, grid-connected current value, grid-connected voltage value and the capacitor input electricity of current transformer
Pressure value；
Current value processing module, for obtaining ac capacitor current value according to the inductor current value, grid-connected current value；
Voltage value processing module, for obtaining ac capacitor voltage value according to the grid-connected voltage value and capacitor input voltage value；
Actual capacity value determining module, for determining institute according to the ac capacitor current value and the ac capacitor voltage value
State the actual capacity value of ac capacitor；
Ac capacitor monitoring modular, for according to the actual capacity value of the ac capacitor and raw capacity value to ac capacitor into
Row monitoring.
8. ac capacitor on-Line Monitor Device according to claim 7, which is characterized in that the actual capacity value determines mould
Block is specifically used for the ac capacitor current value and the ac capacitor voltage value capacitance current differential formulas is imported, by institute
It states the ac capacitor current value in capacitance current differential formulas and the ac capacitor voltage value is converted by three-phase static coordinate system
For two-phase rotating coordinate system, calculates capacitance current differential formulas and obtain the actual capacity value of ac capacitor.
9. a kind of terminal device, including memory, processor and storage are in the memory and can be on the processor
The computer program of operation, which is characterized in that the processor realizes such as claim 1 to 6 when executing the computer program
The step of described in any item ac capacitor on-line monitoring methods.
10. a kind of computer readable storage medium, the computer-readable recording medium storage has computer program, and feature exists
In realization such as ac capacitor as claimed in any one of claims 1 to 6 is monitored on-line when the computer program is executed by processor
The step of method.
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