CN111308311A - Fault diagnosis method and device for filter circuit of converter and storage medium - Google Patents
Fault diagnosis method and device for filter circuit of converter and storage medium Download PDFInfo
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- G—PHYSICS
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- 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
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2832—Specific tests of electronic circuits not provided for elsewhere
- G01R31/2836—Fault-finding or characterising
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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
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2832—Specific tests of electronic circuits not provided for elsewhere
- G01R31/2836—Fault-finding or characterising
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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
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2832—Specific tests of electronic circuits not provided for elsewhere
- G01R31/2836—Fault-finding or characterising
- G01R31/2843—In-circuit-testing
Abstract
The invention discloses a fault diagnosis method, a fault diagnosis device and a storage medium of a converter filter circuit, wherein the fault diagnosis method of the converter filter circuit comprises the following steps: detecting a network side multiphase voltage of the filter circuit; obtaining the current of each phase of capacitance branch circuit according to the network side multiphase voltage and the actual capacitance value of the capacitance of each phase of capacitance branch circuit in the filter circuit; respectively comparing the current of each phase capacitive branch with an instantaneous current threshold, and judging the state of the filter circuit according to the comparison result; the actual capacitance value of the capacitor is determined by the input current of the corresponding phase of the filter circuit and the voltage of the network side when the network side power supply is disconnected. By adopting the embodiment of the invention, the fault diagnosis can be carried out on the filter circuit of the converter in advance, and the fault of the capacitor branch circuit caused by abnormal current is avoided.
Description
Technical Field
The invention relates to the technical field of wind power generation, in particular to a fault diagnosis method and device of a converter filter circuit and a storage medium.
Background
The wind power converter is a core component for electric energy grid connection of the wind generating set, and the grid side of the wind power converter comprises a filter circuit. In the operation process, the network side filter circuit is easily influenced by a power grid or a converter, and phenomena of overcurrent, high harmonic content and the like occur, so that a capacitor branch in the filter circuit breaks down, such as a switch or a capacitor is burnt out.
At present, in order to avoid a fault of a capacitor branch circuit caused by abnormal current, a fuse is added in a filter circuit, and then a protection strategy is executed according to a fuse curve.
However, the inventor of the present application has found that even if the current in the filter circuit is continuously lower than the protection value, heat is always accumulated, which causes the temperature in the filter circuit lines and devices to increase, and if the heat dissipation effect is poor, the switch or the capacitor is burned out. In addition, the fuse needs to be replaced after triggering a fault, and the replacement needs to be stopped, which not only causes cost increase, but also has poor maintainability.
Disclosure of Invention
The embodiment of the invention provides a circuit fault diagnosis method, a circuit fault diagnosis device and a storage medium for current transformer filtering, which can be used for carrying out fault diagnosis on a current transformer filtering circuit in advance and avoiding a fault of a capacitor branch circuit caused by abnormal current.
In a first aspect, an embodiment of the present invention provides a fault diagnosis method for a filter circuit of a converter, where the fault diagnosis method for the filter circuit includes:
detecting a network side multiphase voltage of the filter circuit;
obtaining the current of each phase of capacitance branch circuit according to the network side multiphase voltage and the actual capacitance value of the capacitance of each phase of capacitance branch circuit in the filter circuit;
respectively comparing the current of each phase capacitive branch with an instantaneous current threshold, and judging the state of the filter circuit according to the comparison result;
the actual capacitance value of the capacitor is determined by the input current and the network side voltage of the corresponding phase of the filter circuit when the network side power supply is disconnected.
In one possible embodiment of the first aspect, the input current of the corresponding phase of the filter circuit when the grid-side power supply is disconnected is determined by an intrinsic current sensor on the corresponding phase of the converter.
In a possible implementation manner of the first aspect, determining the state of the filter circuit according to the comparison result includes: and if the current of the capacitor branch circuit of any phase in the filter circuit is larger than the instantaneous current threshold, determining that the filter circuit is in an instantaneous current overrun fault state.
In one possible implementation of the first aspect, after determining that the filter circuit is in the transient current overrun fault condition, the method further comprises: and executing shutdown operation on the wind generating set provided with the converter filter circuit.
In a possible implementation manner of the first aspect, after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit, the method further includes: calculating the root mean square value of the current of each phase capacitive branch in a preset time period; and if the root mean square value of any phase of capacitive branch current in the filter circuit is greater than the effective current threshold value, determining that the filter circuit is in an effective current overrun fault state.
In a possible implementation manner of the first aspect, after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit, the method further includes: carrying out Fourier transform on the current of each phase capacitive branch to obtain multiple harmonics of the current of each phase capacitive branch; if the amplitude of any harmonic in the multiple harmonics is larger than the harmonic amplitude threshold, determining that the harmonic overrun fault occurs in the corresponding phase capacitance branch; and if any phase of capacitive branch in the filter circuit has a harmonic overrun fault, determining that the filter circuit is in a harmonic overrun fault state.
In a possible implementation manner of the first aspect, after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit, the method further includes: calculating the average value or root mean square value of the multi-phase capacitor branch current belonging to the same moment to obtain a neutral current instantaneous value; and if the neutral current instantaneous value is larger than the corresponding neutral current threshold value, determining that the filter circuit is in a neutral current overrun fault state.
In a second aspect, an embodiment of the present invention provides a fault diagnosis apparatus for a filter circuit of a converter, where the fault diagnosis apparatus includes:
the voltage detection module is used for detecting the network side multiphase voltage of the filter circuit;
the branch current calculation module is used for obtaining the current of each phase of capacitance branch circuit according to the network side multiphase voltage and the actual capacitance value of the capacitance of each phase of capacitance branch circuit in the filter circuit;
the comparison processing module is used for respectively comparing the current of each phase of capacitive branch circuit with an instantaneous current threshold;
the fault identification module is used for judging the state of the filter circuit according to the comparison result;
the actual capacitance value of the capacitor is determined by the network side voltage of the filter circuit when the network side power supply is disconnected and the input current of the filter circuit at the corresponding phase.
In a possible embodiment of the second aspect, the fault diagnosis device of the converter filter circuit is provided in a converter controller of the wind turbine generator system.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a program is stored, and the program, when executed by a processor, implements the converter filter circuit fault diagnosis method as described above.
As described above, in the embodiment of the present invention, to implement the early diagnosis of the fault of the filter circuit of the converter, the grid-side multiphase voltage of the filter circuit may be detected first, and the current of each phase capacitive branch may be obtained according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit. Because the network side filter circuit is easily influenced by the current of the power grid in the operation process, the current of each phase of capacitance branch circuit is only required to be compared with the instantaneous current threshold value respectively, and the state of the filter circuit is judged according to the comparison result, so that the fault of the filter circuit of the converter is diagnosed in advance, and the fault of the capacitance branch circuit caused by abnormal current is avoided.
Drawings
The present invention may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which like or similar reference characters identify like or similar features.
Fig. 1 is a grid-connected structure topology of a wind power converter according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a fault diagnosis method for a filter circuit of a converter according to an embodiment of the present invention;
fig. 3 is a schematic current diagram of the a-phase capacitive branch when the network side power supply corresponding to fig. 1 is turned on;
fig. 4 is a schematic current diagram of the a-phase capacitive branch when the grid-side power supply corresponding to fig. 1 is disconnected;
FIG. 5 is a schematic diagram of a subtraction and integration feedback circuit according to an embodiment of the present invention;
fig. 6 is a schematic flowchart of a fault diagnosis method for a filter circuit of a converter according to another embodiment of the present invention;
fig. 7 is a schematic structural diagram of a fault diagnosis apparatus for a filter circuit of a converter according to an embodiment of the present invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention.
Fig. 1 is a grid-connected structure topology of a wind power converter according to an embodiment of the present invention. As shown in fig. 1, the wind power converter includes a machine-side power module and a grid-side filter circuit, and a specific structure of the power module is not shown in fig. 1.
The network-side filter circuit shown in fig. 1 comprises a filter capacitor CfInductor LcAnd a switching device K, also referred to as an LC filter circuit. Inductor L shown in FIG. 1gThe inductor Lg is arranged outside the network side filter circuit, and is also called as an LCL filter circuit when the inductor Lg is arranged in the network side filter circuit. Wherein, the capacitor CfThe branch with the switching device K is referred to as the capacitive branch. FIG. 1 shows three phase capacitor branches a, b, c, where VaIs the network side voltage, V, of the a-phase filter circuitbIs the network side voltage, V, of the b-phase filter circuitcIs the net side voltage of the c-phase filter circuit. In actual operation, a network side filter circuit is easily influenced by the current of a power grid, and phenomena of overcurrent, high harmonic content and the like occur, so that a switch or a capacitor in the filter circuit is burnt out.
Based on the method, the device, the equipment and the storage medium for fault diagnosis of the converter filter circuit, the fault diagnosis of the converter filter circuit can be performed in advance based on the current of the capacitor branch circuit by adopting the embodiment of the invention, and the fault of the capacitor branch circuit caused by abnormal current is avoided.
Fig. 2 is a schematic flowchart of a fault diagnosis method for a filter circuit of a converter according to an embodiment of the present invention. As shown in fig. 2, the fault diagnosis method includes steps 201 to 203.
In step 201, a net-side poly-phase voltage of a filter circuit is detected.
In step 202, the current of each phase capacitive branch is obtained according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit.
In step 203, the current of each phase capacitive branch is compared with the instantaneous current threshold, and the state of the filter circuit is determined according to the comparison result.
The actual capacitance value of the capacitor of each phase capacitance branch can be determined by the corresponding phase input current of the filter circuit and the network side voltage when the network side power supply is disconnected. Due to the fact that the filter capacitor C is prolonged along with the service timefThe capacitance value of the capacitor has deviation, and in order to improve the calculation precision of the current of the capacitor branch circuit, the actual capacitance value of the capacitor is adopted for current calculation.
Specifically, when calculating the actual capacitance value of the capacitor, referring to fig. 3 and 4, the input current i of the filter circuit at the corresponding phase, which is detected by the intrinsic current sensor in the converter, may be first measuredoAssigning to the capacitor branch current icThen, the current i of the capacitor branch circuit is measuredcSubstituting the sum network side voltage into a capacitance voltage and capacitance value calculation formula (1) or a difference formula (2) to obtain a filter capacitance CfThe actual capacitance value of the capacitor.
ic＝Cf×dVc/dt(1)
ic＝Cf×(Vc–Vc_old)/T(2)
Where T is the sampling interval period, which can also be understood as the iterative operation period, VcFor the current sampling moment, the filter capacitor CfVoltage on the network side, VcOld is the filter capacitor C at the previous sampling timefThe grid side voltage of (c).
Fig. 3 is a schematic current diagram of the a-phase capacitive branch when the network side power supply corresponding to fig. 1 is turned on. Wherein ioIs the input current of the network-side filter circuit icFor the a-phase capacitive branch current, it can be seen from FIG. 3 that when the grid side power is turned on, ioIs not equal to ic。
Fig. 4 is a schematic current diagram of the a-phase capacitive branch when the grid-side power supply corresponding to fig. 1 is disconnected. It can be seen that when the network side power supply is disconnected, the inductor LcAnd a phase filter capacitor CfForm a series circuit ofoIs equal to ic。
When in implementation, the network side power supply can be disconnected firstly, so that the inductor LcAnd a phase capacitance branch circuit form a series circuit (namely, the circuit in a broken line frame at the right side in the figure 4 fails), and then the current I in the converter is collectedoI.e. the input current of the filter circuit. By the arrangement, i can be obtained without additionally arranging a current sensor in the filter capacitor branch circuitcThe method has the advantages of small circuit modification and low cost.
Specifically, when the capacitance current branch calculation is performed, the network-side multiphase voltage of the filter circuit and the actual capacitance value of the capacitance of each phase capacitance branch may be respectively substituted into the above formula (1) or formula (2), so as to obtain the branch current of the filter capacitor.
Since the derivation operation in the formula (1) is sensitive to noise, the signal can be filtered before the derivation operation, so as to improve the calculation accuracy. The difference operation in the formula (2) can have higher calculation accuracy without performing filtering processing.
The network-side multiphase voltage of the filter circuit can be obtained by using a voltage sensor or a preset voltage sampling circuit, and if the internal resistance of a circuit and a capacitor is considered, the network-side multiphase voltage can also be obtained by using a subtraction and integration feedback circuit.
Fig. 5 is a schematic structural diagram of a subtraction and integration feedback circuit according to an embodiment of the present invention. The subtraction and integration feedback circuit includes a subtraction operator 501, a multiplication operator 502, and an integration operator 503 in this order.
Wherein the "-" terminal of the subtraction operator 501 and the output of the integration operator 503Terminal connected to receive the output feedback V of the integral operator 503cThe initial value of the "+" terminal of the subtraction operator 501 is V0。
The number of the multiplication operators 502 may be multiple, taking two multiplication operators 502 as an example, the operation principle of the circuit in fig. 5 is as follows: v0Subtracting Vc and multiplying by 1/R to obtain branch current IfUsing formula (1) to IfAnd integrating, multiplying by 1/C to obtain a voltage Vc, and returning the value to the subtracter to be used as an input value of the next iteration to finally obtain a real Vc value.
As described above, in the embodiment of the present invention, to implement the early diagnosis of the fault of the filter circuit of the converter, the grid-side multiphase voltage of the filter circuit may be detected first, and the current of each phase capacitive branch may be obtained according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit. Because the network side filter circuit is easily influenced by the current of the power grid in the operation process, the current of each phase of capacitance branch circuit is only required to be compared with the instantaneous current threshold value respectively, and the state of the filter circuit is judged according to the comparison result, so that the fault of the filter circuit of the converter is diagnosed in advance, and the fault of the capacitance branch circuit caused by abnormal current is avoided.
For example, if the current of the capacitor branch of any phase in the filter circuit is greater than the instantaneous current threshold, it indicates that the current in the filter circuit is too large, so that it can be determined that the filter circuit is in an instantaneous current overrun fault state, and at this time, the wind turbine generator system needs to be stopped in time to ensure the operation safety of the wind turbine generator system.
On the contrary, if the capacitor branch currents of all the phases in the filter circuit are all smaller than or equal to the instantaneous current threshold, the current in the filter circuit is within the allowable operation range, so that the filter circuit can be determined to be in a normal state, and the wind generating set does not need to be processed.
For example, in actual operation, the technical scheme based on the embodiment of the invention can diagnose the current overrun fault of the filter circuit in the level of mus, so that the converter can respond in time, the fault of a capacitor branch circuit caused by abnormal current is avoided, and if the fault can be realized based on a high-speed CPU, the response time can be shortened to ns level.
In addition, the filter capacitor C is considered to be prolonged along with the service timefThe capacitance value of the filter circuit is determined based on the inherent sensor on the corresponding phase of the filter circuit when the network side power supply is disconnected so as to calculate the actual capacitance value of the filter capacitor, so that the calculation precision of the capacitance branch current can be improved, namely, the diagnosis precision of the fault of the filter circuit of the converter is improved, and the hardware does not need to be added in the converter, namely, the hardware maintenance cost is not increased, and the operation reliability of the converter is not reduced due to the hardware fault.
In addition, if it is known that a certain error exists in the filter capacitor, a certain tolerance interval should be added in the fault diagnosis process to prevent false triggering of the fault. For example, in identifying a transient current overrun fault, if the capacitance value C is knownfIf there is an error of. + -. a%, the current i can be found from the formula (1)cThe error of +/-a% also exists, therefore, the a% can be increased on the basis of the original instantaneous current threshold value, and the updated instantaneous current threshold value can be obtained.
It should be noted that the technical solution in the embodiment of the present invention is not limited to the three-phase three-wire circuit shown in fig. 1, but is also applicable to a single-phase circuit, a three-phase four-wire circuit, a delta connection three-phase three-wire circuit, and the like, and is not limited herein.
Further, besides the instantaneous current overrun fault, the state of the filter circuit can be judged from the aspects of other multiple fault types, including an effective current overrun fault, a harmonic overrun fault, a neutral current overrun fault and the like.
The following describes a filter capacitor fault diagnosis method for each fault type in detail.
Firstly, for the diagnosis of the fault that the effective current exceeds the limit, the root mean square value of the current of each phase capacitive branch in a preset time period, namely the effective value of the current, can be calculated, wherein the preset period refers to a power frequency period of a power grid. If the root mean square value of any phase of capacitive branch current in the filter circuit is greater than the effective current threshold value, the effective current in the filter circuit is too large, the filter circuit can be determined to be in an effective current overrun fault state, and at the moment, the wind generating set needs to be shut down to ensure the running safety of the wind generating set.
On the contrary, if the root mean square values of the capacitor branch currents of all the phases in the filter circuit are all smaller than or equal to the effective current threshold, the filter circuit is in a normal working state, and at the moment, no treatment measures are needed to be carried out on the wind generating set.
Secondly, for the diagnosis of the harmonic overrun fault, the current of each phase of capacitive branch can be subjected to Fourier transform to obtain multiple harmonics of each phase of capacitive branch current, if the amplitude of any harmonic in the multiple harmonics is larger than a harmonic amplitude threshold value, the harmonic overrun of the branch current of the filter capacitor is indicated, the harmonic overrun fault of the corresponding phase of capacitive branch can be determined, if the harmonic overrun fault of any phase of capacitive branch in the filter circuit is indicated, the harmonic overrun of the whole filter circuit is indicated, and at the moment, the wind generating set needs to be shut down to ensure the operation safety of the wind generating set.
On the contrary, if no harmonic overrun fault occurs in all the filtering branches in the filtering circuit, it indicates that no harmonic overrun occurs in the whole filtering circuit, and no treatment measure needs to be performed on the wind generating set at this time.
Thirdly, calculating the average value or root-mean-square value of the currents of the multi-phase capacitor branches belonging to the same moment aiming at the diagnosis of the over-limit fault of the neutral current to obtain the instantaneous value of the neutral current; if the neutral current instantaneous value is larger than the corresponding neutral current threshold value, the filter circuit is determined to be in a neutral current overrun fault state, and at the moment, the wind generating set needs to be stopped to ensure the operation safety of the wind generating set.
On the contrary, if the neutral current instantaneous value is less than or equal to the corresponding neutral current threshold value, the filter circuit is determined to be in a normal working state, and no treatment measures are needed to be carried out on the wind generating set at the moment.
It should be noted that the above-mentioned various fault diagnosis processes may be executed in parallel or may be executed sequentially. Fig. 6 is a schematic flow chart of a fault diagnosis method for a filter circuit of a converter according to another embodiment of the present invention, which includes steps 601-614, and is used to illustrate a sequential implementation manner in conjunction with fig. 4.
In step 601, collecting a network side multiphase voltage signal of a filter circuit;
in step 602, the network side voltage signal is filtered (only for formula (1);
in step 603, the current i of the capacitor branch circuit is calculated according to the filtered voltage signal and the actual capacitance value of the capacitorc；
In step 604, any phase i is determinedcIf not, executing step 605, otherwise executing step 606;
in step 605, reporting an instantaneous current overrun fault;
in step 606, i in the fundamental frequency period is calculatedcA valid value of (a);
in step 607, any phase i is judgedcIf yes, go to step 608, otherwise go to step 609;
in step 608, an active current overrun fault is declared;
in step 609, for icPerforming Fourier transform;
in step 610, any phase i is determinedcIf the harmonic wave is out of limit, execute step 611 if yes, otherwise execute step 612;
in step 611, a harmonic overrun fault is reported;
in step 612, based on three phases icCalculating the neutral current;
in step 613, determining whether the neutral current is over-limit, if so, executing step 613, otherwise, returning to step 601;
in step 614, a line current overrun fault is declared.
It should be noted that, for a system without a neutral line (for example, a three-phase three-wire star connection system, a three-phase three-wire angle connection system, etc.), since there is no neutral line current, the neutral line current overrun detection module is invalid, and a person skilled in the art can select a necessary fault determination module according to actual situations, which is not limited herein.
It should be further noted that the fault diagnosis method in the embodiment of the present invention is also applicable to an off-grid converter, where the off-grid converter is a converter that a grid-connected end of a grid-connected converter is directly connected to a load, that is, the off-grid converter is equivalent to an ac power supply. When the actual capacitance value of the filter capacitor in the off-grid converter is calculated, the load is only required to be disconnected.
Fig. 7 is a schematic structural diagram of a fault diagnosis device for a filter circuit of a converter according to an embodiment of the present invention. As shown in fig. 7, the filter circuit fault diagnosis apparatus includes a voltage detection module 701, a branch current calculation module 702, a comparison processing module 703, and a fault identification module 704.
The voltage detection module 701 is configured to detect a net-side multiphase voltage of the filter circuit.
The branch current processing module 702 is configured to obtain the capacitance of each phase capacitive branch according to the network-side multiphase voltage and the actual capacitance value of the capacitance of each phase capacitive branch in the filter circuit.
The actual capacitance value of the capacitor is determined by the network side voltage of the filter circuit when the network side power supply is disconnected and the input current of the filter circuit at the corresponding phase.
The comparison processing module 703 compares the current of each phase capacitive branch with the instantaneous current threshold respectively.
And a fault identification module 704 for judging the state of the filter circuit according to the comparison result.
It should be noted that the fault diagnosis device of the converter filter circuit in the embodiment of the present invention may be integrated in a converter controller of a wind turbine generator system, so that any adjustment on existing hardware is not required, and the fault diagnosis device may also be disposed in a logic device having an independent operation function, which is not limited herein.
Embodiments of the present invention also provide a computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, the method for diagnosing the fault of the filter circuit of the converter is implemented.
It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. For the device embodiments, reference may be made to the description of the method embodiments in the relevant part. Embodiments of the invention are not limited to the specific steps and structures described above and shown in the drawings. Those skilled in the art may make various changes, modifications and additions to, or change the order between the steps, after appreciating the spirit of the embodiments of the invention. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of an embodiment of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.
Embodiments of the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the algorithms described in the specific embodiments may be modified without departing from the basic spirit of the embodiments of the present invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the embodiments of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (10)
1. A fault diagnosis method for a filter circuit of a converter is characterized by comprising the following steps:
detecting a net side multiphase voltage of the filter circuit;
obtaining the current of each phase of capacitance branch circuit according to the network side multiphase voltage and the actual capacitance value of the capacitance of each phase of capacitance branch circuit in the filter circuit;
respectively comparing the current of each phase capacitive branch with an instantaneous current threshold, and judging the state of the filter circuit according to the comparison result;
and the actual capacitance value of the capacitor is determined by the input current and the network side voltage of the corresponding phase of the filter circuit when the network side power supply is disconnected.
2. The method of claim 1, wherein the input current for the corresponding phase of the filter circuit when the grid side power supply is off is determined by an intrinsic current sensor of the corresponding phase in the current transformer.
3. The method of claim 1, wherein determining the state of the filter circuit according to the comparison comprises:
and if the current of the capacitor branch circuit of any phase in the filter circuit is larger than the instantaneous current threshold value, determining that the filter circuit is in an instantaneous current overrun fault state.
4. The method of claim 3, further comprising, after said determining that said filter circuit is in an instantaneous current over-limit fault state: and executing shutdown operation on the wind generating set provided with the converter filter circuit.
5. The method according to claim 1, further comprising, after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit, further:
calculating the root mean square value of the current of each phase capacitive branch in a preset time period;
and if the root mean square value of any phase of capacitive branch current in the filter circuit is greater than the effective current threshold value, determining that the filter circuit is in an effective current overrun fault state.
6. The method according to claim 1, further comprising, after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitor of each phase capacitive branch in the filter circuit, further:
carrying out Fourier transform on the current of each phase capacitive branch to obtain multiple harmonics of the current of each phase capacitive branch;
if the amplitude of any harmonic in the multiple harmonics is larger than the harmonic amplitude threshold, determining that the harmonic overrun fault occurs in the corresponding phase capacitance branch;
and if any phase of capacitive branch in the filter circuit has a harmonic overrun fault, determining that the filter circuit is in a harmonic overrun fault state.
7. The method according to claim 1, wherein after obtaining the current of each phase capacitive branch according to the grid-side multiphase voltage and the actual capacitance value of the capacitance of each phase capacitive branch in the filter circuit, the method further comprises:
calculating the average value or root mean square value of the multi-phase capacitor branch current belonging to the same moment to obtain a neutral current instantaneous value;
and if the neutral current instantaneous value is larger than the corresponding neutral current threshold value, determining that the filter circuit is in a neutral current overrun fault state.
8. A converter filter circuit fault diagnosis apparatus, comprising:
the voltage detection module is used for detecting the network side multiphase voltage of the filter circuit;
the branch current calculation module is used for obtaining the current of each phase of capacitance branch circuit according to the network side multiphase voltage and the actual capacitance value of the capacitance of each phase of capacitance branch circuit in the filter circuit;
the comparison processing module is used for respectively comparing the current of each phase of capacitive branch circuit with an instantaneous current threshold;
the fault identification module is used for judging the state of the filter circuit according to the comparison result;
and the actual capacitance value of the capacitor is determined by the network side voltage of the filter circuit and the input current of the filter circuit at the corresponding phase when the network side power supply is disconnected.
9. The apparatus of claim 8, wherein the fault diagnostic device of the converter filter circuit is disposed in a converter controller of a wind turbine generator system.
10. A computer-readable storage medium, on which a program is stored, which, when being executed by a processor, carries out a converter filter circuit fault diagnosis method according to any one of claims 1 to 7.
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