CN114114088B - Nuclear power auxiliary transformer high-voltage side open-phase discrimination method and device - Google Patents
Nuclear power auxiliary transformer high-voltage side open-phase discrimination method and device Download PDFInfo
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- CN114114088B CN114114088B CN202111289724.9A CN202111289724A CN114114088B CN 114114088 B CN114114088 B CN 114114088B CN 202111289724 A CN202111289724 A CN 202111289724A CN 114114088 B CN114114088 B CN 114114088B
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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
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention discloses a method and a device for discriminating the phase failure of a high-voltage side of a nuclear power auxiliary transformer, comprising the following steps: s1: collecting three-phase current and three-phase voltage of a high-voltage side of a nuclear power auxiliary transformer; s2: judging whether the nuclear power auxiliary transformer is in a grid-connected state or not; s3: judging whether the effective value of the fundamental current of each phase line is larger than a second preset value or not, and judging whether the effective value of the harmonic current of the corresponding phase line is larger than a third preset value or not; if yes, judging that the phase line is broken. By implementing the technical scheme of the invention, the problem that the single-phase broken wire cannot be accurately identified under the no-load state by using the criterion of low phase line current is effectively solved, the judgment result is accurate, and the safety of equipment can be better ensured.
Description
Technical Field
The invention relates to the technical field of power system safety, in particular to a method and a device for judging the phase failure of a high-voltage side of a nuclear power auxiliary transformer.
Background
Currently, a 220kV system standby power supply system is configured in a nuclear power station, and the system is generally composed of a 220kV bus power supply, a 220kV power transmission line and a 220kV auxiliary transformer. The 220kV system standby power supply system needs to bear the function of power supply when the generator set is shut down for maintenance or fails.
The existing auxiliary transformer open-phase monitoring device is mainly monitored through phase current or negative sequence current. On the one hand, the nuclear power auxiliary transformer is in an idle running state for a long time, when the capacitive current of a line is large or the idle exciting current is small, the phase current change after the high-voltage side is broken is small, and the identification by using the criterion of low phase current is difficult; on the other hand, when the nuclear power auxiliary transformer is in a load-carrying running state, the nuclear power auxiliary transformer is influenced by negative sequence current caused by load unbalance, and the negative sequence current criterion has risks of misoperation and refusal. Therefore, when the high-voltage side opposite side circuit of the nuclear power auxiliary transformer is broken, the effective identification is difficult to be carried out by using the existing criteria, and an alarm is sent out timely, if the load is required to be switched to the auxiliary transformer during shutdown maintenance of the nuclear power unit at the moment, the three-phase load of the auxiliary transformer is unbalanced, the additional loss can be caused due to unbalanced magnetic circuit, and the one-phase winding with larger load can be overheated and tripped, so that the safe operation of the nuclear power station is endangered.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method and a device for judging the phase failure of a high-voltage side of a nuclear power auxiliary transformer aiming at least one defect existing in the prior art.
The technical scheme adopted for solving the technical problems is as follows: a method for distinguishing the open phase of the high-voltage side of a nuclear power auxiliary transformer is constructed, which comprises the following steps:
s1: collecting three-phase current and three-phase voltage of a high-voltage side of a nuclear power auxiliary transformer;
s2: calculating positive sequence voltage amplitude of a high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltage, judging whether the nuclear power auxiliary transformer is in a grid-connected state according to whether the positive sequence voltage amplitude is larger than a first preset value, and if so, executing step S3;
s3: calculating the fundamental current and the harmonic current effective value of each phase line according to the three-phase current, judging whether the fundamental current effective value of each phase line is larger than a second preset value or not, and judging whether the harmonic current effective value of the corresponding phase line is larger than a third preset value or not; if yes, judging that the phase line is broken.
Preferably, in the method for discriminating the open phase of the high-voltage side of the nuclear power auxiliary transformer, the criterion that the positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer is greater than a first preset value is as follows:
when the formula (1) is satisfied, judging that the nuclear power auxiliary transformer is in a grid-connected state:
wherein U is h1 Positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer; u (U) set The method comprises the steps of determining a first preset value for judging that the positive sequence voltage of the high-voltage side of the nuclear power auxiliary transformer is high; k (K) 1 Is the first compensation coefficient; u (U) n Is the rated voltage of the high-voltage side of the nuclear power auxiliary transformer.
Preferably, in the method for judging the open-phase at the high-voltage side of the auxiliary transformer for nuclear power according to the present invention, the criterion for judging whether the effective value of the fundamental current of each phase line is greater than the second preset value is as follows:
when the formula (2) is satisfied, determining that the effective value of the fundamental current of the corresponding phase line is larger than a second preset value:
wherein I is 1_X The method comprises the steps that the method is a fundamental current effective value of an X phase line on a high-voltage side of a nuclear power auxiliary transformer, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 1_set The method comprises the steps of determining a second preset value for judging that the effective value of fundamental wave current at the high-voltage side of the nuclear power auxiliary transformer is high; k (K) 2 Is the second compensation coefficient; i b0 And the no-load exciting current is used for the high-voltage side of the nuclear power auxiliary transformer.
Preferably, in the method for discriminating a phase failure at a high voltage side of a nuclear power auxiliary transformer according to the present invention, when the effective value of the fundamental current of at least one phase line is greater than the second preset value, it is further determined whether the sum of the effective values of even harmonic currents of the corresponding phase lines is greater than a third preset value, where the criterion is as follows:
when the equation (3) is satisfied, it is determined that the even-numbered harmonic current effective value of the corresponding phase line is greater than a third preset value:
wherein I is ∑2_X The method comprises the steps that the sum of even-numbered harmonic current effective values of an X phase line of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 2_set The method comprises the steps of determining a third preset value with high effective value of even harmonic current on the high-voltage side of the nuclear power auxiliary transformer; i n1_X Is the effective value of the X-phase even harmonic of the high voltage side of the nuclear power auxiliary transformer, wherein n is 1 Is a positive even number; k (K) 3 Is the third compensation coefficient.
Preferably, in the method for discriminating a phase failure at a high voltage side of a nuclear power auxiliary transformer according to the present invention, when the effective value of the fundamental current of at least one phase line is greater than the second preset value, it is further determined whether the ratio of the sum of the effective values of odd harmonic currents of the corresponding phase line to the sum of the effective values of even harmonic currents of the phase line is less than a fourth preset value, where the criterion is as follows:
when the formula (4) is satisfied, determining that the ratio of the sum of the effective values of odd harmonic currents of the corresponding phase line on the high-voltage side of the nuclear power auxiliary transformer to the sum of the effective values of even harmonic currents of the phase line is smaller than a fourth preset value:
wherein I is ∑1_X The method comprises the steps that the sum of effective values of odd-order harmonic currents of X phases of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phases comprise an A phase line, a B phase line and a C phase line; k (k) 4 A fourth preset value for judging that the ratio of the sum of the effective values of the odd-numbered harmonic currents to the sum of the effective values of the even-numbered harmonic currents of the X phase is low; i n2_X Is the effective value of the odd-order harmonic of the X phase at the high voltage side of the nuclear power auxiliary transformer, wherein n 2 Is a positive odd number other than 1.
Preferably, in the method for judging the phase interruption at the high voltage side of the auxiliary nuclear power transformer according to the present invention, steps S1 to S3 are repeatedly executed within a duration T after a phase interruption is judged for the first time, and if the judgment is true within the duration T, the corresponding phase interruption is judged.
The invention solves the technical problem and also constructs a high-voltage side open-phase distinguishing device of the nuclear power auxiliary transformer, which comprises the following components:
the acquisition circuit is used for acquiring three-phase current and three-phase voltage of the high-voltage side of the nuclear power auxiliary transformer;
the information processing circuit is used for calculating positive sequence voltage amplitude values of the high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltage and calculating fundamental wave current and harmonic current effective values of each phase line according to the three-phase current;
and the logic processing circuit is used for judging whether the positive sequence voltage amplitude is larger than a first preset value, the fundamental wave current effective value is larger than a second preset value and the harmonic current effective value is larger than a third preset value.
Preferably, in the device for discriminating a phase failure at a high voltage side of a nuclear power auxiliary transformer according to the present invention, the collecting circuit includes a current detecting unit CT for collecting three-phase current at the high voltage side of the nuclear power auxiliary transformer, and a voltage detecting unit PT for collecting three-phase voltage at the high voltage side of the nuclear power auxiliary transformer.
Preferably, in the high-voltage side open-phase discriminating device of a nuclear power auxiliary transformer according to the present invention, the current detecting unit CT includes an optical current transformer, and the voltage detecting unit PT includes an inductive voltage transformer.
The invention has at least the following beneficial effects: the method for judging the single-phase broken line of the opposite side line of the nuclear power auxiliary high-voltage side is constructed, and whether the phase line is abnormal or not is judged according to the fact that whether the fundamental current and the harmonic current of each phase line are abnormal or not, so that the problem that when the line capacitive current is larger than the no-load exciting current of the nuclear power auxiliary transformer, the single-phase broken line cannot be accurately identified under the no-load state by the criterion that the phase line current is low is effectively solved, the judging result is accurate and reliable, and the safety of equipment can be better ensured.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a flow chart of an embodiment of a method for discriminating a phase failure at a high voltage side of a nuclear power auxiliary transformer according to the present invention;
fig. 2 is a schematic diagram of a high-voltage side open-phase discrimination device of the nuclear power auxiliary transformer of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 1 is a flowchart of a first embodiment of a method for discriminating a high-voltage side open phase of a nuclear power auxiliary transformer according to the present invention, the implementation method includes: step S1, step S2, step S3.
Step S1: collecting three-phase current and three-phase voltage of a high-voltage side of a nuclear power auxiliary transformer;
step S2: calculating positive sequence voltage amplitude of a high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltage, judging whether the nuclear power auxiliary transformer is in a grid-connected state according to whether the positive sequence voltage amplitude is larger than a first preset value, and if so, executing step S3;
optionally, in step S2, it is determined whether the auxiliary nuclear power transformer is in a grid-connected state, where the specific criterion needs to satisfy formula (1):
wherein U is h1 Positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer; u (U) set For judging the first pre-stage of the positive sequence voltage of the high-voltage side of the nuclear power auxiliary transformerSetting a value; k (K) 1 Is the first compensation coefficient; u (U) n Is the rated voltage of the high-voltage side of the nuclear power auxiliary transformer.
When the nuclear power auxiliary transformer is in an offline state, the positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer is low level, and after the nuclear power auxiliary transformer enters a grid-connected state, the positive sequence voltage amplitude of the nuclear power auxiliary transformer is close to rated voltage, so that whether the nuclear power auxiliary transformer is in the grid-connected state can be judged according to whether the positive sequence voltage amplitude is larger than a first preset value or not. Further, since the transmission line is long and has line loss, in order to improve the accuracy of the calculation result, a first compensation coefficient K is added 1 First compensation coefficient K 1 0.5 to 0.8 of the total weight of the plant extract can be taken.
Step S3: calculating fundamental current and harmonic current effective values of each phase line according to the three-phase currents, judging whether the fundamental current effective values of each phase line are larger than a second preset value or not, and judging whether the harmonic current effective values of the corresponding phase lines are larger than a third preset value or not; if yes, judging that the phase line is broken.
Optionally, in step S2, it is determined whether the effective value of the fundamental current of each phase line is greater than a second preset value, and the specific criterion needs to satisfy equation (2):
wherein I is 1_X The method is characterized in that the method is a fundamental wave current effective value of an X phase line of a high-voltage side of a nuclear power auxiliary transformer, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 1_set The method comprises the steps of determining a second preset value for judging that the effective value of fundamental wave current at the high-voltage side of the nuclear power auxiliary transformer is high; k (K) 2 Is the second compensation coefficient; i b0 And the no-load exciting current is used for the high-voltage side of the nuclear power auxiliary transformer.
When the nuclear power auxiliary transformer is in an idle state, the capacitive current of the line is larger than the idle excitation current of the nuclear power auxiliary transformer due to the long power transmission line. If a phase line at the high-voltage side of the nuclear power auxiliary transformer has a broken line fault, the power transmission line charges and discharges the nuclear power auxiliary transformer due to the capacitive power transmission line, and the fundamental wave current effective value of the nuclear power auxiliary transformer is obtained at the momentWill increase and therefore it is possible to determine whether a phase failure has occurred based on whether the fundamental current effective value is greater than the second preset value. Further, in order to improve the accuracy of the calculation result, a second compensation coefficient K is added 2 Second compensation coefficient K 2 0.5 to 0.8 of the total weight of the plant extract can be taken.
Abnormal states such as grid fluctuation and external interference exist, and the effective value of the fundamental wave current is increased. In order to improve the reliability of the judgment result, therefore, when the effective value of the fundamental current of at least one phase line is larger than the second preset value, whether the sum of the effective values of even harmonic currents of the corresponding phase lines is larger than the third preset value is also judged, and the specific criterion needs to satisfy the formula (3):
wherein I is ∑2_X The method comprises the steps that the sum of even harmonic current effective values of an X phase line of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 2_set The method comprises the steps of determining a third preset value with high effective value of even harmonic current on the high-voltage side of the nuclear power auxiliary transformer; i n1_X Is the effective value of the X-phase even harmonic of the high voltage side of the nuclear power auxiliary transformer, wherein n is 1 Is a positive even number; k (K) 3 Is the third compensation coefficient.
When the nuclear power auxiliary transformer works normally, the three-phase load is balanced, the amplitudes of the even-numbered harmonic effective values of the phase lines are similar, and the vector sum of the phases is close to zero. Therefore, when the three-phase load is balanced, the sum of the effective values of the even harmonic currents is close to zero. When open-phase faults occur, the three-phase load is unbalanced, and the sum of the effective values of even harmonic currents is increased. Therefore, whether the phase line has a phase failure can be further judged according to whether the sum of the effective values of even harmonic currents of the nuclear power auxiliary transformer is larger than a third preset value. Further, in order to improve the accuracy of the calculation result, a third compensation coefficient K is added 3 Third compensation coefficient K 3 0.1 to 0.3 of the total weight of the composition can be taken.
Optionally, when the effective value of the fundamental current of at least one phase line is greater than the second preset value, it is further determined whether the ratio of the sum of the effective values of the odd-numbered harmonic currents of the corresponding phase line to the sum of the effective values of the even-numbered harmonic currents of the phase line is less than the fourth preset value, where the specific criterion needs to satisfy equation (4):
wherein I is ∑1_X The method is characterized in that the sum of effective values of odd-order harmonic currents of X phases of a high-voltage side of a nuclear power auxiliary transformer is used, wherein the X phases comprise an A phase line, a B phase line and a C phase line; k (k) 4 A fourth preset value for judging that the ratio of the sum of the effective values of the odd-numbered harmonic currents to the sum of the effective values of the even-numbered harmonic currents of the X phase is low; i n2_X Is the effective value of the odd-order harmonic of the X phase at the high voltage side of the nuclear power auxiliary transformer, wherein n 2 Is a positive odd number other than 1.
To prevent odd harmonics from being too large, resulting in an effective value of fundamental current I 1_X And the sum of the even harmonic current effective values I ∑2_X The increase affects the judgment, so that whether the phase line has a phase failure or not can be further judged according to whether the ratio of the sum of the effective values of the odd-numbered harmonic currents of the nuclear power auxiliary transformer to the sum of the effective values of the even-numbered harmonic currents of the phase line is smaller than a fourth preset value. Wherein, the fourth preset value K 4 0.33 may be taken.
Optionally, after determining that a phase line is disconnected for the first time, steps S1 to S3 are repeatedly executed within a duration T, and if the determinations are all true within the duration T, the corresponding phase line is determined to be disconnected.
In order to avoid direct output of erroneous judgment results caused by factors such as power grid fluctuation or external interference, the steps S1 to S3 are repeatedly executed within the time T, and the corresponding phase line is judged to be broken when all criteria are met, so that the accuracy of the judgment results is improved. Wherein the time T may take 100ms.
As shown in fig. 2, the invention also constructs a device for judging the open-phase of the high-voltage side of the nuclear power auxiliary transformer, which comprises an acquisition circuit, an information processing circuit and a logic processing circuit.
And the acquisition circuit is used for acquiring three-phase current and three-phase voltage of the high-voltage side of the nuclear power auxiliary transformer.
And the information processing circuit is used for calculating positive sequence voltage amplitude values of the high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltages and calculating fundamental wave current and harmonic current effective values of each phase line according to the three-phase currents.
And the logic processing circuit is used for judging whether the positive sequence voltage amplitude is larger than a first preset value, the fundamental wave current effective value is larger than a second preset value and the harmonic current effective value is larger than a third preset value.
Optionally, judging whether the nuclear power auxiliary transformer is in a grid-connected state, wherein a specific criterion needs to satisfy a formula (1):
wherein U is h1 Positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer; u (U) set The method comprises the steps of determining a first preset value for judging that the positive sequence voltage of the high-voltage side of the nuclear power auxiliary transformer is high; k (K) 1 Is the first compensation coefficient; u (U) n Is the rated voltage of the high-voltage side of the nuclear power auxiliary transformer.
Optionally, judging whether the effective value of the fundamental current of each phase line is larger than a second preset value, wherein a specific criterion needs to satisfy the formula (2):
wherein I is 1_X The method is characterized in that the method is a fundamental wave current effective value of an X phase line of a high-voltage side of a nuclear power auxiliary transformer, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 1_set The method comprises the steps of determining a second preset value for judging that the effective value of fundamental wave current at the high-voltage side of the nuclear power auxiliary transformer is high; k (K) 2 Is the second compensation coefficient; i b0 And the no-load exciting current is used for the high-voltage side of the nuclear power auxiliary transformer.
Optionally, when the effective value of the fundamental current of at least one phase line is greater than a second preset value, it is further determined whether the sum of the effective values of even harmonic currents of the corresponding phase lines is greater than a third preset value, and the specific criterion needs to satisfy formula (3):
wherein I is ∑2_X The method comprises the steps that the sum of even harmonic current effective values of an X phase line of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 2_set The method comprises the steps of determining a third preset value with high effective value of even harmonic current on the high-voltage side of the nuclear power auxiliary transformer; i n1_X Is the effective value of the X-phase even harmonic of the high voltage side of the nuclear power auxiliary transformer, wherein n is 1 Is a positive even number; k (K) 3 Is the third compensation coefficient.
Optionally, when the effective value of the fundamental current of at least one phase line is greater than the second preset value, it is further determined whether the ratio of the sum of the effective values of the odd-numbered harmonic currents of the corresponding phase line to the sum of the effective values of the even-numbered harmonic currents of the phase line is less than the fourth preset value, where the specific criterion needs to satisfy equation (4):
wherein I is ∑1_X The method is characterized in that the sum of effective values of odd-order harmonic currents of X phases of a high-voltage side of a nuclear power auxiliary transformer is used, wherein the X phases comprise an A phase line, a B phase line and a C phase line; k (k) 4 A fourth preset value for judging that the ratio of the sum of the effective values of the odd-numbered harmonic currents to the sum of the effective values of the even-numbered harmonic currents of the X phase is low; i n2_X Is the effective value of the odd-order harmonic of the X phase at the high voltage side of the nuclear power auxiliary transformer, wherein n 2 Is a positive odd number other than 1.
Optionally, the acquisition circuit comprises a current detection unit CT for acquiring three-phase current at the high-voltage side of the nuclear power auxiliary transformer and a voltage detection unit PT for acquiring three-phase voltage at the high-voltage side of the nuclear power auxiliary transformer. The current detection unit CT includes an optical current transformer, and the voltage detection unit PT includes an inductive voltage transformer.
The invention has at least the following beneficial effects: the method for judging the single-phase broken line of the opposite side line of the nuclear power auxiliary high-voltage side is constructed, and whether the phase line is abnormal or not is judged according to the fact that whether the fundamental current and the harmonic current of each phase line are abnormal or not, so that the problem that when the line capacitive current is larger than the no-load exciting current of the nuclear power auxiliary transformer, the single-phase broken line cannot be accurately identified under the no-load state by the criterion that the phase line current is low is effectively solved, the judging result is accurate and reliable, and the safety of equipment can be better ensured.
It is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the invention; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Claims (8)
1. The method for discriminating the phase failure of the high-voltage side of the nuclear power auxiliary transformer is characterized by comprising the following steps of:
s1: collecting three-phase current and three-phase voltage of a high-voltage side of a nuclear power auxiliary transformer;
s2: calculating positive sequence voltage amplitude of a high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltage, judging whether the nuclear power auxiliary transformer is in a grid-connected state according to whether the positive sequence voltage amplitude is larger than a first preset value, and if so, executing step S3;
s3: calculating the fundamental current and the harmonic current effective value of each phase line according to the three-phase current, judging whether the fundamental current effective value of each phase line is larger than a second preset value or not, and judging whether the harmonic current effective value of the corresponding phase line is larger than a third preset value or not; if yes, judging that the phase line is broken; when the effective value of the fundamental current of at least one phase line is larger than the second preset value, judging whether the sum of the effective values of even harmonic currents of the corresponding phase lines is larger than a third preset value, wherein the criterion is as follows:
when the equation (3) is satisfied, it is determined that the even-numbered harmonic current effective value of the corresponding phase line is greater than a third preset value:
wherein I is ∑2_X The method comprises the steps that the sum of even-numbered harmonic current effective values of an X phase line of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 2_set Is a third preset value; i n1_X Is the effective value of the X-phase even harmonic of the high voltage side of the nuclear power auxiliary transformer, wherein n is 1 Is a positive even number; k (K) 3 Is the third compensation coefficient; i 1_X The effective value of the fundamental wave current of the X phase line at the high voltage side of the nuclear power auxiliary transformer.
2. The method for distinguishing the open-phase of the high-voltage side of the nuclear power auxiliary transformer according to claim 1, wherein the criterion that the positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer is larger than a first preset value is as follows:
when the formula (1) is satisfied, judging that the nuclear power auxiliary transformer is in a grid-connected state:
wherein U is h1 Positive sequence voltage amplitude of the high-voltage side of the nuclear power auxiliary transformer; u (U) set Is a first preset value; k (K) 1 Is the first compensation coefficient; u (U) n Is the rated voltage of the high-voltage side of the nuclear power auxiliary transformer.
3. The method for judging whether the effective value of the fundamental current of each phase line is greater than a second preset value according to claim 1, wherein the criterion for judging whether the effective value of the fundamental current of each phase line is greater than the second preset value is as follows:
when the formula (2) is satisfied, determining that the effective value of the fundamental current of the corresponding phase line is larger than a second preset value:
wherein I is 1_X The method comprises the steps that the method is a fundamental current effective value of an X phase line on a high-voltage side of a nuclear power auxiliary transformer, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 1_set Is a second preset value; k (K) 2 Is the second compensation coefficient; i b0 And the no-load exciting current is used for the high-voltage side of the nuclear power auxiliary transformer.
4. The method for determining a phase interruption at a high voltage side of a nuclear power auxiliary transformer according to claim 3, wherein when the effective value of the fundamental current of at least one phase line is greater than the second preset value, it is further determined whether the ratio of the sum of the effective values of the odd-numbered harmonic currents of the corresponding phase line to the sum of the effective values of the even-numbered harmonic currents of the phase line is smaller than a fourth preset value, as follows:
when the formula (4) is satisfied, determining that the ratio of the sum of the effective values of odd harmonic currents of the corresponding phase line on the high-voltage side of the nuclear power auxiliary transformer to the sum of the effective values of even harmonic currents of the phase line is smaller than a fourth preset value:
wherein I is ∑1_X The method comprises the steps that the sum of effective values of odd-order harmonic currents of X phases of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phases comprise an A phase line, a B phase line and a C phase line; k (k) 4 A fourth preset value; i n2_X Is the effective value of the odd-order harmonic of the X phase at the high voltage side of the nuclear power auxiliary transformer, wherein n 2 Is a positive odd number other than 1.
5. The method according to any one of claims 1 to 4, further comprising repeating steps S1 to S3 for a duration T after determining that a certain phase line is disconnected for the first time, and determining that the corresponding phase line is disconnected if the determinations are all true for the duration T.
6. The utility model provides a nuclear power auxiliary transformer high voltage side phase failure distinguishing device which characterized in that includes:
the acquisition circuit is used for acquiring three-phase current and three-phase voltage of the high-voltage side of the nuclear power auxiliary transformer;
the information processing circuit is used for calculating positive sequence voltage amplitude values of the high-voltage side of the nuclear power auxiliary transformer according to the three-phase voltage and calculating fundamental wave current and harmonic current effective values of each phase line according to the three-phase current;
the logic processing circuit is used for judging whether the positive sequence voltage amplitude is larger than a first preset value, the fundamental wave current effective value is larger than a second preset value and the harmonic current effective value is larger than a third preset value or not; when the effective value of the fundamental current of at least one phase line is larger than the second preset value, judging whether the sum of the effective values of even harmonic currents of the corresponding phase lines is larger than a third preset value, wherein the criterion is as follows:
when the equation (3) is satisfied, it is determined that the even-numbered harmonic current effective value of the corresponding phase line is greater than a third preset value:
wherein I is ∑2_X The method comprises the steps that the sum of even-numbered harmonic current effective values of an X phase line of a high-voltage side of a nuclear power auxiliary transformer is obtained, wherein the X phase line comprises an A phase line, a B phase line and a C phase line; i 2_set Is a third preset value; i n1_X Is the effective value of the X-phase even harmonic of the high voltage side of the nuclear power auxiliary transformer, wherein n is 1 Is a positive even number; k (K) 3 Is the third compensation coefficient; i 1_X The effective value of the fundamental wave current of the X phase line at the high voltage side of the nuclear power auxiliary transformer.
7. The device for distinguishing the open-phase of the high-voltage side of the nuclear power auxiliary transformer according to claim 6, wherein the acquisition circuit comprises a current detection unit CT for acquiring three-phase current of the high-voltage side of the nuclear power auxiliary transformer and a voltage detection unit PT for acquiring three-phase voltage of the high-voltage side of the nuclear power auxiliary transformer.
8. The device for discriminating a high-voltage side loss of phase of a nuclear power auxiliary transformer according to claim 7 wherein said current detecting unit CT includes an optical current transformer and said voltage detecting unit PT includes an inductive voltage transformer.
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| CN202111289724.9A CN114114088B (en) | 2021-11-02 | 2021-11-02 | Nuclear power auxiliary transformer high-voltage side open-phase discrimination method and device |
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