CN110927565B - Open-circuit fault positioning method for SVG (static var generator) main loop switching device - Google Patents

Open-circuit fault positioning method for SVG (static var generator) main loop switching device Download PDF

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CN110927565B
CN110927565B CN201911075111.8A CN201911075111A CN110927565B CN 110927565 B CN110927565 B CN 110927565B CN 201911075111 A CN201911075111 A CN 201911075111A CN 110927565 B CN110927565 B CN 110927565B
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circuit fault
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switching device
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CN110927565A (en
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朱永元
龚立锋
王东
唐轶
王杨
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Zhangjiagang Power Supply Branch Of State Grid Jiangsu Electric Power Co ltd
China University of Mining and Technology CUMT
Suzhou Power Supply Co of State Grid Jiangsu Electric Power Co Ltd
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Zhangjiagang Power Supply Branch Of State Grid Jiangsu Electric Power Co ltd
China University of Mining and Technology CUMT
Suzhou Power Supply Co of State Grid Jiangsu Electric Power 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
    • G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
    • 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
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Abstract

The invention relates to an open-circuit fault positioning method for a SVG main circuit switch device, which comprises the following steps: for SVGxOf AC-side network with phase output current, SVGxSampling the phase voltage to obtain a sampling current sumNA sampling voltage; computingxReactive power corresponding to the positive half-wave and reactive power corresponding to the negative half-wave of the phase; computingxAn open circuit fault characteristic value of a phase; according toxAnd judging the position of the open-circuit fault by the relationship between the open-circuit fault characteristic value of the phase and a plurality of preset threshold values. The method can accurately and reliably position the open-circuit fault of the SVG main circuit switching device, is not influenced by load fluctuation, and solves the problem that the existing diagnosis method cannot distinguish the open-circuit fault of the IGBT and the freewheeling diode.

Description

Open-circuit fault positioning method for SVG main loop switching device
Technical Field
The invention belongs to the field of inverter fault diagnosis, and particularly relates to an open-circuit fault positioning method for a SVG (static var generator) main circuit switching device.
Background
Inverters are increasingly used in industrial production. The inverter necessarily uses power switching devices with high switching frequency. According to statistics from over 200 surveys of 80 companies, the power device faults account for more than 60% of the frequency converter faults, so that the rapid positioning of the fault power devices is very important for the inverter.
At present, a plurality of inverter power device fault diagnosis methods are available, and current detection is most commonly used, such as a PARK vector method, a current vector trajectory method and the like. However, these methods are only applicable to the variable frequency speed control system, and are not applicable to SVG, because the ac side of the variable frequency speed control system is connected to the motor, which belongs to the inductive load. However, SVG needs to work under two conditions of sensitivity and capacitance, so the reliability of these determination methods is difficult to guarantee.
The open-circuit faults of the power switching device comprise an IGBT open circuit and a free-wheeling diode open circuit, and because the current directions of an upper tube IGBT and a lower tube diode are consistent all the time, the diagnosis method based on the current magnitude cannot further distinguish the open-circuit faults of the IGBT and the diode. Therefore, the fault judgment of the power device is difficult, and the method is worthy of research.
Disclosure of Invention
The invention aims to provide a method for accurately and reliably positioning the open-circuit fault of the SVG main loop switch device.
In order to achieve the purpose, the invention adopts the technical scheme that:
the utility model provides a SVG main loop switch device open circuit fault location method for open circuit fault takes place the position and fixes a position in the SVG, SVG is including the three circuit unit that corresponds the three-phase, every the circuit unit include switching device, lower switching device, with go up the parallelly connected diode that goes up switching device, with the parallelly connected diode that goes down switching device, SVG main loop switch device open circuit fault location method is: x e (a, b, c), and respectively executing the following steps on the x phase of the SVG:
step 1: sampling the x-phase output current of the SVG and the x-phase voltage of the AC side power grid of the SVG simultaneously, and sampling in each period to obtain N sampling currents ix(k) And N sampling voltages ux(k) N is a positive even number, k is 1, 2, …, N, and then step 2 is performed;
step 2: based on the x phaseSampling current ix(k) And a sampling voltage ux(k) Calculating the reactive power corresponding to the positive half wave of the x phase in the current period
Figure BDA0002262193370000011
Reactive power corresponding to negative half wave
Figure BDA0002262193370000012
Then, executing the step 3;
and step 3: reactive power corresponding to positive half wave based on x phase
Figure BDA0002262193370000021
Reactive power corresponding to negative half wave
Figure BDA0002262193370000022
According to
Figure BDA0002262193370000023
Figure BDA0002262193370000024
Calculating an open-circuit fault eigenvalue for the x-phase
Figure BDA0002262193370000025
And 4, step 4: judgment of
Figure BDA0002262193370000026
If yes, alpha is a preset first threshold value, beta is a preset second threshold value, beta is less than 0 and less than alpha, if yes, the x-phase is in open circuit fault, and the step 5 is continuously executed;
and 5: judgment of
Figure BDA0002262193370000027
If yes, gamma is a preset third threshold value, epsilon is a preset fourth threshold value, beta is more than epsilon and less than 0 and gamma is more than alpha, if yes, the step is executed6, if not, executing the step 7;
step 6: judging whether n is positive or not, if yes, the upper switching device corresponding to x has an open-circuit fault, and if not, the lower switching device corresponding to x has an open-circuit fault;
and 7: and judging whether n is true or not, if so, the upper diode corresponding to x has an open-circuit fault, and if not, the lower diode corresponding to x has an open-circuit fault.
In the step 1, N is a multiple of 4.
In the step 1, the x-phase output current is collected through a current transformer, and the x-phase voltage of the alternating-current side power grid is collected through a voltage transformer.
In the step 2, reactive power corresponding to the positive half wave of the x phase is calculated by using a method of shifting the voltage of the alternating-current side power grid by 90 degrees
Figure BDA0002262193370000028
Reactive power corresponding to negative half wave
Figure BDA0002262193370000029
According to
Figure BDA00022621933700000210
Calculating the reactive power corresponding to the positive half wave of the x phase
Figure BDA00022621933700000211
Reactive power corresponding to negative half wave
Figure BDA00022621933700000212
In the step 4, | β | ═ α |; in the step 5, | epsilon | ═ γ |.
In the step 4, α is 0.4, and β is-0.4; in step 5, γ is 0.2 and ∈ is-0.2.
The upper switch tube and the lower switch tube are both IGBTs.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the method can accurately and reliably position the open-circuit fault of the SVG main circuit switching device, is not influenced by load fluctuation, and solves the problem that the existing diagnosis method cannot distinguish the open-circuit fault of the IGBT and the freewheeling diode.
Drawings
Fig. 1 is a three-phase four-wire system two-level SVG electrical topology diagram.
FIG. 2 is a flow chart of the method of the present invention.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.
The first embodiment is as follows: the SVG as shown in fig. 1 includes three circuit units corresponding to three phases, each circuit unit including an upper switching device, a lower switching device, an upper diode connected in parallel with the upper switching device, and a lower diode connected in parallel with the lower switching device. For example, for phase a, the corresponding circuit unit includes an upper switching device T1, a lower switching device T4, an upper diode D1 connected in parallel across the upper switching device T1, and a lower diode D4 connected in parallel across the lower switching device, and the upper switching device T1 and the lower switching device T4 are connected in series. And the midpoint between the upper switching device T1 and the lower switching device T4 forms its output and connects the resistor R and the inductor L. In this SVG, each upper switching tube and each lower switching tube are IGBTs, and therefore, may be referred to as an upper tube IGBT and a lower tube IGBT.
As shown in fig. 2, for the SVG, an open-circuit fault locating method for locating an open-circuit fault occurrence position in the SVG is as follows:
x epsilon (a, b and c) respectively represent a phase, a phase b and a phase c. Respectively executing the following steps on the x phase of the SVG:
step 1: and (5) collecting analog quantity signals.
Sampling the x-phase output current of the SVG and the x-phase voltage of the AC side power grid of the SVG at the same time, and sampling in each period to obtain N sampling currents ix(k) And N sampling voltages ux(k) N is a positive even number, usually a multiple of 4, and k is equal to1, 2, …, N, and then step 2 is performed.
In the step, x-phase output current is collected through a current transformer, and x-phase voltage of an alternating-current side power grid is collected through a voltage transformer.
Step 2: and calculating reactive power.
Sampling current i based on x phasex(k) And a sampling voltage ux(k) Calculating the reactive power corresponding to the positive half wave of the x phase in the current period
Figure BDA0002262193370000031
Reactive power corresponding to negative half wave
Figure BDA0002262193370000032
Then step 3 is performed.
In the step, one period of each phase of network side voltage is averagely divided into two intervals, wherein the phase of the network side voltage is 90-270 degrees, namely an interval I, and the phase of the network side voltage is 270-90 degrees, namely an interval II. Calculating the reactive power corresponding to the positive half wave of the x phase by using a method of shifting the voltage of the alternating-current side power grid by 90 degrees
Figure BDA0002262193370000033
Reactive power corresponding to negative half wave
Figure BDA0002262193370000034
The calculation formula is as follows:
Figure BDA0002262193370000041
and 3, step 3: and calculating an open-circuit fault characteristic value (normalized value).
Reactive power corresponding to positive half wave based on x phase
Figure BDA0002262193370000042
Reactive power corresponding to negative half wave
Figure BDA0002262193370000043
According to
Figure BDA0002262193370000044
Figure BDA0002262193370000045
Calculating an open-circuit fault eigenvalue for the x-phase
Figure BDA0002262193370000046
As a result, 6 numbers of the three phases were obtained
Figure BDA0002262193370000047
When an open-circuit fault of an IGBT or a freewheeling diode of a certain phase occurs, positive or negative half-wave current of each period output by the SVG three-phase is lost, and corresponding reactive power of the SVG three-phase is correspondingly changed. The IGBT of the lower tube is open-circuited, and the corresponding reactive power of the negative half-wave current of the phase is reduced; the freewheeling diode of the upper tube is opened, and the corresponding reactive power of the negative half-wave current of the phase is reduced, so 6 freewheeling diodes
Figure BDA0002262193370000048
Corresponds to the operating condition of one IGBT or diode. Taking phase a as an example, the following:
Figure BDA00022621933700000411
judging whether the phase a upper tube IGBT or the phase a lower tube diode is open-circuited,
Figure BDA00022621933700000412
and judging whether the IGBT or the upper diode tube of the phase a lower tube is open-circuited or not, and so on.
And 4, step 4: and judging the phase of the fault.
Judgment of
Figure BDA0002262193370000049
And if the first threshold value is not satisfied, alpha is a preset first threshold value, beta is a preset second threshold value, and beta is less than 0 and less than alpha, and | beta | ═ alpha |. If so,the x-phase has an open circuit fault and step 5 continues. Typically, α is 0.4 and β is-0.4.
And 5: and judging the switching device or the diode where the fault is located.
Judgment of
Figure BDA00022621933700000410
And if yes, gamma is a preset third threshold value, epsilon is a preset fourth threshold value, and | epsilon | ═ gamma |, beta < epsilon < 0 < gamma < alpha. If yes, go to step 6, otherwise go to step 7. Typically, γ is 0.2 and ε is-0.2.
Step 6: and judging the position of the fault.
And judging whether n is positive or not, if yes, generating open-circuit fault on the upper switch device corresponding to x, and if not, generating open-circuit fault on the lower switch device corresponding to x.
And 7: and judging the position of the fault.
And judging whether n is true or not, if so, generating open-circuit fault on the upper diode corresponding to x, and otherwise, generating open-circuit fault on the lower diode corresponding to x.
According to the scheme, when
Figure BDA0002262193370000051
And judging that the IGBT on the x phase has a fault.
When in use
Figure BDA0002262193370000052
Or
Figure BDA0002262193370000053
And judging that the tube diode in the x-phase tube is in fault.
The judgment process is further explained:
if it is
Figure BDA0002262193370000054
Judging to be a capacitive working condition, if any
Figure BDA0002262193370000055
Then x phase upper tubeThe IGBT is opened; otherwise if there is
Figure BDA0002262193370000056
The tube diode is open for x-phase.
If it is
Figure BDA0002262193370000057
Judging as a sensitive working condition, if any
Figure BDA0002262193370000058
The X-phase upper tube IGBT is opened; if it is
Figure BDA0002262193370000059
The freewheeling diode is open-circuited for the x-phase lower tube.
Based on
Figure BDA00022621933700000510
The determination of (2) is similar to the above process, and the specific correspondence is shown in the following table.
Figure BDA00022621933700000511
The above embodiments are only for illustrating the technical idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the protection scope of the present invention by this means. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (7)

1. The utility model provides a SVG main loop switch device open circuit fault location method for open circuit fault takes place the position to fixing a position in the SVG, the SVG is including the three circuit unit that corresponds the three-phase, every the circuit unit include switching device, lower switching device, with go up the parallelly connected diode that goes up switching device, with the parallelly connected diode that goes down switching device, its characterized in that: the SVG main loop switch device open-circuit fault positioning method comprises the following steps: x e (a, b, c), and respectively executing the following steps on the x phase of the SVG:
step 1: sampling the x-phase output current of the SVG and the x-phase voltage of the AC side power grid of the SVG simultaneously, and sampling in each period to obtain N sampling currents ix(k) And N sampling voltages ux(k) N is a positive even number, k is 1, 2, …, N, and then step 2 is performed;
and 2, step: the sampling current i based on x phasex(k) And a sampling voltage ux(k) Calculating the reactive power corresponding to the positive half-wave of the x phase in the current period
Figure FDA0003646806800000011
Reactive power corresponding to negative half wave
Figure FDA0003646806800000012
Then, executing the step 3;
and step 3: reactive power corresponding to positive half wave based on x phase
Figure FDA0003646806800000013
Reactive power corresponding to negative half wave
Figure FDA0003646806800000014
According to
Figure FDA0003646806800000015
Figure FDA0003646806800000016
Calculating an open-circuit fault eigenvalue for the x-phase
Figure FDA0003646806800000017
And 4, step 4: judgment of
Figure FDA0003646806800000018
If yes, alpha is a preset first threshold value, beta is a preset second threshold value, beta is less than 0 and less than alpha, and | beta |, i α |, if yes, the x-phase has an open-circuit fault, and the step 5 is continuously executed;
and 5: judgment of
Figure FDA0003646806800000019
If yes, gamma is a preset third threshold value, epsilon is a preset fourth threshold value, beta is more than epsilon and less than 0 and less than gamma and less than alpha, and if not, the step 6 is executed, and if not, the step 7 is executed;
step 6: judging whether n is positive or not, if yes, the upper switching device corresponding to x has an open-circuit fault, and if not, the lower switching device corresponding to x has an open-circuit fault;
and 7: and judging whether n is true or not, if so, the upper diode corresponding to x has an open-circuit fault, and if not, the lower diode corresponding to x has an open-circuit fault.
2. The SVG main circuit switching device open-circuit fault locating method according to claim 1, wherein: in the step 1, N is a multiple of 4.
3. The SVG main circuit switching device open-circuit fault locating method according to claim 1, wherein: in the step 1, the x-phase output current is collected through a current transformer, and the x-phase voltage of the AC-side power grid is collected through a voltage transformer.
4. The SVG main circuit switching device open-circuit fault locating method according to claim 1, wherein: in the step 2, the reactive power corresponding to the positive half wave of the x phase is calculated by using a method of shifting the voltage of the alternating-current side power grid by 90 degrees
Figure FDA0003646806800000021
Reactive power corresponding to negative half wave
Figure FDA0003646806800000022
5. The SVG main circuit switching device open-circuit fault locating method of claim 4, characterized by: according to
Figure FDA0003646806800000023
Calculating the reactive power corresponding to the positive half wave of the x phase
Figure FDA0003646806800000024
Reactive power corresponding to negative half wave
Figure FDA0003646806800000025
6. The SVG main circuit switching device open-circuit fault locating method according to claim 1, wherein: in the step 4, α is 0.4, and β is-0.4; in step 5, γ is 0.2 and ∈ is-0.2.
7. The SVG main loop switching device open-circuit fault location method of claim 1, characterized in that: the upper switch tube and the lower switch tube are both IGBTs.
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