CN110993251B - Phase selection and switching-off based transformer core demagnetization method and system - Google Patents
Phase selection and switching-off based transformer core demagnetization method and system Download PDFInfo
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- CN110993251B CN110993251B CN201911076964.3A CN201911076964A CN110993251B CN 110993251 B CN110993251 B CN 110993251B CN 201911076964 A CN201911076964 A CN 201911076964A CN 110993251 B CN110993251 B CN 110993251B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F13/00—Apparatus or processes for magnetising or demagnetising
- H01F13/006—Methods and devices for demagnetising of magnetic bodies, e.g. workpieces, sheet material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
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- Protection Of Transformers (AREA)
Abstract
The invention discloses a phase selection and switching-off based transformer iron core demagnetizing method and a system, wherein the method comprises the following steps: receiving a brake separating signal, analyzing the brake separating signal, and judging whether the brake separating signal is in a non-fault removal condition; judging whether the opening signal is a non-fault removal condition, and removing a load side circuit breaker of the transformer; any two-phase circuit breaker on the power supply side of the transformer is disconnected, and three-phase voltage on the power supply side of the transformer is detected in real time; when the monitored three-phase voltage of the power supply side of the transformer meets a preset relation condition, monitoring the amplitude of the third-phase voltage running at the power supply side of the transformer; when the amplitude of the running third-phase voltage reaches a peak value, the third-phase circuit breaker is disconnected, and the demagnetization of the transformer iron core is completed; according to the method and the system, the phase selection control device is used for controlling the switching-off time sequence of the transformer to realize demagnetization according to the magnetic linkage characteristic among three phases of the transformer, the effect is stable, the implementation is simple and easy, and the practical value is better.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a phase selection switching-off based transformer core demagnetizing method and system.
Background
The transformer iron core demagnetizing technology refers to: and the residual magnetism in the iron core is eliminated by using related equipment, so that the magnetic domain of the iron core is restored to a disordered state, the magnetic flux path is improved, and the accuracy of the transformer test is further improved. The degaussing methods adopted at present mainly include the following two methods:
d, direct current demagnetization: a dc current is applied to the transformer winding and the polarity is constantly reversed. The current applied in each time is 5% -10% of the previous time until the current is reduced to 5mA. The transformer is automatically discharged each time before the polarity of the current is changed. By the direct-current demagnetization method, the area of a hysteresis loop of the transformer core can be reduced. When this area is sufficiently small, demagnetization can be considered successful.
An alternating current demagnetization method: the neutral point of the high-voltage side of the transformer is grounded and has no load. And applying alternating voltage phase by phase on the low-voltage side of the transformer by adopting a no-load pressurization method, gradually increasing the voltage to 30 percent of rated voltage, and keeping the voltage for a certain time. Then, the applied voltage was again slowly decreased to 0V. After the applied voltage is reduced to 0V, the voltage is slowly increased again to 30% of the rated voltage, and the no-load exciting current is obviously reduced every time after the voltage is repeatedly increased.
However, the two methods have the disadvantages of requiring professional personnel to perform field operation by means of additional equipment, being complicated to operate and the like, and have a lot of inconvenience in practical application.
Disclosure of Invention
In order to solve the problems that the existing iron core demagnetizing methods in the prior art need to contact additional equipment and are complicated to operate, the invention provides a phase selection and switching-off based transformer iron core demagnetizing method and a phase selection and switching-off based transformer iron core demagnetizing system, wherein the phase selection and switching-off control device is used for controlling the switching-off time sequence of a transformer to realize demagnetization according to the magnetic linkage characteristics among three phases of the transformer, and the phase selection and switching-off based transformer iron core demagnetizing method comprises the following steps:
receiving a brake separating signal, analyzing the brake separating signal, and judging whether the brake separating signal is in a non-fault removal condition;
judging whether the opening signal is in a non-fault removal condition, and removing a load side circuit breaker of the transformer;
any two-phase circuit breaker on the power supply side of the transformer is disconnected, and three-phase voltage on the power supply side of the transformer is detected in real time;
when the monitored three-phase voltage of the power supply side of the transformer meets a preset relation condition, monitoring the amplitude of the third-phase voltage running at the power supply side of the transformer;
and when the amplitude of the running third-phase voltage reaches a peak value, disconnecting the third-phase circuit breaker and finishing the demagnetization of the transformer iron core.
Further, the three-phase voltage at the power supply side of the transformer meets the preset relation condition that: the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third phase in operation.
Further, the monitoring time is started to time while the three-phase voltage of the power supply side of the transformer is monitored in real time;
and when the monitored three-phase voltage at the power supply side of the transformer does not meet the preset condition relation within preset time, directly disconnecting the third-phase circuit breaker when the amplitude of the running third-phase voltage reaches the next peak value.
Further, if the opening signal is judged to be the fault removal condition, the demagnetization of the transformer iron core is not needed.
The transformer core demagnetization system based on phase selection and opening comprises:
the signal analysis unit is used for receiving the brake separating signal, analyzing the brake separating signal and judging whether the brake separating signal is in a non-fault removal condition;
the phase selection control unit is used for cutting off a load side circuit breaker of the transformer when the signal analysis unit judges that the opening signal is in a non-fault cutting-off condition;
the phase selection control unit is used for simultaneously disconnecting any two-phase circuit breaker on the power supply side of the transformer;
the detection unit is used for detecting the three-phase voltage of the power supply side of the transformer in real time and detecting whether the three-phase voltage of the power supply side of the transformer meets a preset relation condition or not; the detection unit detects the amplitude of the third phase voltage running at the power supply side of the transformer when the three-phase voltage at the power supply side of the transformer meets the preset relation condition;
when the detection unit detects that the amplitude of the running third-phase voltage reaches a peak value, a disconnection instruction is sent to the phase selection control unit; and the phase selection control unit disconnects the third phase circuit breaker according to a disconnection instruction.
Further, the three-phase voltage at the power supply side of the transformer meets the preset relation condition that: the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third phase in operation.
Further, the detection unit is used for starting monitoring time timing while monitoring the three-phase voltage of the power supply side of the transformer in real time;
when the monitored three-phase voltage of the power supply side of the transformer does not meet a preset condition relation within preset time, the detection unit detects the amplitude of the third phase voltage, and sends a disconnection instruction to the phase selection control unit when the amplitude of the running third phase voltage reaches the next peak value; and the phase selection control unit disconnects the third-phase circuit breaker according to the disconnection instruction.
Furthermore, if the signal analysis unit judges that the opening signal is in a fault removal condition, the signal is ignored, and the demagnetization of the transformer iron core is not needed.
The invention has the beneficial effects that: the technical scheme of the invention provides a phase selection and switching-off based transformer iron core demagnetization method and a phase selection and switching-off based transformer iron core demagnetization system, wherein the method and the system control the switching-off time sequence of a transformer to realize demagnetization by using a phase selection control device according to the magnetic linkage characteristics among three phases of the transformer; the method and the system can be realized only by means of phase selection control, the defect that a professional carries out on-site complicated operation by means of additional equipment is overcome, residual magnetism remaining in the iron core after the transformer is cut off can be eliminated more conveniently and effectively when the transformer is not cut off, the method and the system are stable in effect, simple and easy to realize, have better practical value and ensure the accuracy of a transformer test.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of a phase-selection switching-off based transformer core demagnetizing method according to an embodiment of the present invention;
fig. 2 is a structural diagram of a transformer core demagnetizing system based on phase selection and switching-off according to an embodiment of the present invention.
Detailed Description
Example embodiments of the present invention will now be described with reference to the accompanying drawings, however, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are provided for a complete and complete disclosure of the invention and to fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same unit/element is denoted by the same reference numeral.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a phase-selection switching-off based transformer core demagnetizing method according to an embodiment of the present invention; as shown in fig. 1, the method includes:
in this embodiment, whether the received opening signal is an opening signal under the condition of fault removal is distinguished, and if the received opening signal is judged to be the opening signal under the condition of fault removal, the method belongs to a countermeasure for the fault condition, and is not a condition that the transformer core needs to be demagnetized under the condition of conventional non-fault removal, and subsequent operations and demagnetization of the transformer core are not required.
if the situation is judged to be the non-fault removal situation, the iron core of the transformer needs to be demagnetized, and the transformer is in a no-load running state by removing the breaker on the load side of the transformer.
in this embodiment, the transformer is a three-phase dual-winding transformer, and the relationship between the primary-side three-phase voltages of the transformer (i.e. the two phases are disconnected) under the condition that the primary-side two-phase is opened (and the two phases are disconnected) can be obtained according to the calculation of a symmetric component method (taking the operation example of the phase a and the phase B as follows): namely, the phase B and the phase C have the same voltage and are 1/2 of the voltage of the phase A, and the angle is 180 degrees different from the phase A; and because there is a direct relation between the voltage flux linkages, i.e., E =4.44f ψ. Therefore, it can be seen that the relationship between the magnetic chains is also the relationship between the magnetic chains corresponding to the three phases as long as the conditional relationship is satisfied between the voltages
Therefore, in this embodiment, the condition that the three-phase voltage on the power supply side of the transformer meets the preset relation is that the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third running phase.
When the three-phase voltage on the power supply side of the transformer meets the conditions, whether the amplitude of the running third-phase voltage reaches a peak value or not needs to be detected, and the third-phase circuit breaker is cut off when the amplitude of the third-phase voltage reaches the peak value, so that the residual magnetism in the transformer is minimum.
And 150, when the amplitude of the running third-phase voltage reaches a peak value, disconnecting the third-phase circuit breaker to complete demagnetization of the transformer iron core.
Further, in order to ensure the stability of the operation of the power grid, it is not desirable to continuously maintain the demagnetization mode, in this embodiment, the monitoring time is started while the three-phase voltage on the power supply side of the transformer is monitored in real time;
and when the monitored three-phase voltage at the power supply side of the transformer does not meet the preset condition relation within preset time, directly disconnecting the third-phase circuit breaker when the amplitude of the running third-phase voltage reaches the next peak value.
Fig. 2 is a structural diagram of a transformer core demagnetizing system based on phase selection and switching-off according to an embodiment of the present invention. As shown in fig. 2, the system includes:
the signal analysis unit 210 is configured to receive a brake separating signal, analyze the brake separating signal, and determine whether the brake separating signal is a non-fault-removal condition;
further, if the signal analyzing unit 210 determines that the opening signal is a fault clearing condition, the signal is ignored, and the transformer core does not need to be demagnetized.
The phase selection control unit 220, where the phase selection control unit 220 is configured to cut off a load-side circuit breaker of the transformer when the signal analysis unit 210 determines that the tripping signal is a non-fault cut-off condition;
the phase selection control unit 220 is configured to simultaneously disconnect any two phase circuit breakers on the power supply side of the transformer;
the detection unit 230 is used for detecting the three-phase voltage of the power supply side of the transformer in real time and detecting whether the three-phase voltage of the power supply side of the transformer meets a preset relation condition; when the three-phase voltage at the power supply side of the transformer meets the preset relation condition, the detection unit 230 detects the amplitude of the third-phase voltage running at the power supply side of the transformer;
further, the three-phase voltage at the power supply side of the transformer meets the preset relation condition that: the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third phase in operation.
When the detecting unit 230 detects that the amplitude of the running third phase voltage reaches a peak value, a disconnection instruction is sent to the phase selection control unit; the phase selection control unit 220 opens the third phase breaker according to the opening instruction.
Further, the detecting unit 230 is configured to start monitoring time timing while monitoring the three-phase voltage at the power supply side of the transformer in real time;
when the monitored three-phase voltage on the power supply side of the transformer does not meet the preset condition relationship within the preset time, the detection unit 230 detects the amplitude of the third phase voltage, and sends a disconnection instruction to the phase selection control unit 220 when the amplitude of the operated third phase voltage reaches the next peak value; the phase selection control unit 220 opens the third phase breaker according to the opening instruction.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore, may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Reference to step numbers in this specification is only for distinguishing between steps and is not intended to limit the temporal or logical relationship between steps, which includes all possible scenarios unless the context clearly dictates otherwise.
Moreover, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination.
Various component embodiments of the disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure may also be embodied as devices or system programs (e.g., computer programs and computer program products) for performing some or all of the methods described herein. Such programs implementing the present disclosure may be stored on a computer-readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
Claims (8)
1. A transformer iron core demagnetizing method based on phase selection and opening comprises the following steps:
receiving a brake separating signal, analyzing the brake separating signal, and judging whether the brake separating signal is in a non-fault removal condition;
judging whether the opening signal is a non-fault removal condition, and removing a load side circuit breaker of the transformer;
any two-phase circuit breaker on the power supply side of the transformer is disconnected, and three-phase voltage on the power supply side of the transformer is detected in real time;
when the monitored three-phase voltage of the power supply side of the transformer meets a preset relation condition, monitoring the amplitude of the third-phase voltage running at the power supply side of the transformer;
and when the amplitude of the running third-phase voltage reaches the peak value, disconnecting the third-phase circuit breaker to finish the demagnetization of the transformer iron core.
2. The method of claim 1, wherein: the three-phase voltage of the power supply side of the transformer meets the preset relation condition that: the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third phase in operation.
3. The method according to claim 1 or 2, characterized in that:
starting monitoring time timing while monitoring three-phase voltage of a power supply side of the transformer in real time;
and when the monitored three-phase voltage at the power supply side of the transformer does not meet the preset condition relation within preset time, directly disconnecting the third-phase circuit breaker when the amplitude of the running third-phase voltage reaches the next peak value.
4. The method of claim 1, wherein: and if the opening signal is judged to be the fault removal condition, the demagnetization of the transformer iron core is not needed.
5. A phase-selection separating-gate based transformer core demagnetizing system, comprising:
the signal analysis unit is used for receiving the brake separating signal, analyzing the brake separating signal and judging whether the brake separating signal is in a non-fault removal condition;
the phase selection control unit is used for cutting off a load side circuit breaker of the transformer when the signal analysis unit judges that the switching-off signal is in a non-fault cutting-off condition;
the phase selection control unit is used for simultaneously disconnecting any two phase circuit breakers on the power supply side of the transformer;
the detection unit is used for detecting the three-phase voltage of the power supply side of the transformer in real time and detecting whether the three-phase voltage of the power supply side of the transformer meets a preset relation condition or not; the detection unit detects the amplitude of the third phase voltage running at the power supply side of the transformer when the three-phase voltage at the power supply side of the transformer meets the preset relation condition;
when the detection unit detects that the amplitude of the running third-phase voltage reaches a peak value, a disconnection instruction is sent to the phase selection control unit; and the phase selection control unit disconnects the third phase circuit breaker according to the disconnection instruction.
6. The system of claim 5, wherein: the three-phase voltage of the power supply side of the transformer meets the preset relation condition that: the phase voltages of any two disconnected phases are equal and are-1/2 of the voltage of the third phase in operation.
7. The system according to claim 5 or 6, characterized in that: the detection unit is used for starting monitoring time timing while monitoring three-phase voltage of the power supply side of the transformer in real time;
when the monitored three-phase voltage on the power supply side of the transformer does not meet the preset condition relation within preset time, the detection unit detects the amplitude of the third-phase voltage, and sends a disconnection instruction to the phase selection control unit when the amplitude of the running third-phase voltage reaches the next peak value; and the phase selection control unit disconnects the third phase circuit breaker according to a disconnection instruction.
8. The system of claim 5, wherein: and if the signal analysis unit judges that the opening signal is in the fault removal condition, neglecting the signal and not needing to demagnetize the iron core of the transformer.
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| CN201911076964.3A CN110993251B (en) | 2019-11-06 | 2019-11-06 | Phase selection and switching-off based transformer core demagnetization method and system |
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| CN110993251B true CN110993251B (en) | 2022-12-13 |
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