CN109888733B - Early warning type motor protection method and device - Google Patents
Early warning type motor protection method and device Download PDFInfo
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Abstract
The invention provides an early warning type three-phase motor protection method and device, wherein the method comprises the steps of collecting and calculating each phase voltage and each phase current of a three-phase power supply loop of a motor, obtaining first monitoring parameters, comparing each first monitoring parameter with a corresponding protection threshold value respectively, and judging whether asymmetric short-circuit fault occurs according to a comparison result; comparing the zero sequence voltage and the zero sequence current with corresponding protection thresholds, and judging whether a ground fault occurs; integrating the first monitoring parameters with time to obtain integral monitoring parameters of the first monitoring parameters in each time period, which are collectively called as second monitoring parameters; and comparing and judging each second monitoring parameter with a corresponding time integral threshold value to realize electric potential safety hazard early warning. The invention can realize comprehensive and efficient monitoring of electrical safety.
Description
Technical Field
The invention relates to the field of motor protection, in particular to an early warning type motor protection method and device.
Background
Along with the large-scale popularization of power equipment such as electric power application and various motor pumps, motors, elevators and the like, the number of motor safety accidents is also remarkably increased. In the field of power systems and other production, most of the damage to electrical machines is caused by breakdown of the insulation. The adoption of negative sequence protection and zero sequence protection is a universal motor comprehensive protection technical means at home and abroad, and particularly aims at the insulation fault protection of motor interphase asymmetrical short circuit, grounding and the like.
According to incomplete statistics, the number of 1KW-320KW low-voltage motors running in the whole country is 6000 thousands, accounts for more than 70% of the power consumption of a power grid, and is the most widely applied power equipment in industrial, agricultural and commercial systems. The number of the motors burned in the whole country is about 300 million every year, the capacity is 10 hundred million kilowatts, only the motors consume hundreds of millions of degrees every year in the burning process, the repair cost is as high as about 100 hundred million yuan, and the production stop loss is 100 hundred million yuan. In addition, the power is reduced after the motor is repaired, the power consumption is high, and the normal production of enterprises is directly influenced by the performance deterioration.
During the operation of the motor, faults such as undercurrent, overload, phase failure, locked rotor, short circuit, overvoltage, undervoltage, electric leakage, three-phase imbalance, overheating, grounding, bearing abrasion, stator and rotor eccentricity, winding aging and the like often occur. The motor comprehensive protection technology is a necessary guarantee for various motor fault protection, but the motor comprehensive protection equipment works in the initial transient process after an electrical fault occurs, at the moment, voltage and current signals contain attenuated direct current components and complex harmonic components to generate serious distortion, and the motor comprehensive protection function is greatly weakened. With the rapid development of electrical intelligent technology, the motor has various requirements on frequent starting, braking, positive and negative rotation, variable load and the like, and is easier to burn out windings than the prior motor, and particularly, the occurrence frequency of faults such as overload, short circuit, phase failure, chamber sweeping and the like is the highest.
In fact, the monitoring and early warning for early hidden dangers in the motor are more important, the prevention is in the future, the social and economic cost can be greatly saved, and the safety and the important guarantee for industrial production are also provided. Early insulation hidden trouble signals in the motor are weak, the motor is easily interfered by the outside, misjudgment and misoperation can be formed, and the existing electric comprehensive protection technology cannot meet the basic requirements of no operation rejection and no misoperation.
Disclosure of Invention
The invention aims to provide a motor safety monitoring and early warning method and device based on data aggregation optimization processing of negative sequence and zero sequence electrical parameters, so as to overcome the defects and shortcomings of single motor electric safety monitoring means, limited application of monitoring technology and the like in the prior art and realize comprehensive and efficient monitoring of motor electric safety.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides an early warning type three-phase motor protection method, which comprises the following steps:
s1, collecting and calculating each phase voltage and current of the three-phase power supply loop of the motor, and carrying out comprehensive protection processing on the motor;
s2, obtaining a first monitoring parameter according to each phase voltage and each phase current, wherein the first monitoring parameter comprises: each phase of negative sequence current, zero sequence current, negative sequence voltage and zero sequence voltage;
comparing the zero sequence voltage and the zero sequence current with corresponding protection thresholds respectively, and judging whether a ground fault occurs;
if the ground fault is judged not to occur, the negative sequence voltage and the negative sequence current are respectively compared with corresponding protection thresholds, and whether an asymmetric short-circuit fault occurs or not is judged according to a comparison result;
s3, integrating the first monitoring parameters with time to obtain integrated monitoring parameters of the first monitoring parameters in each time period, which are collectively called as second monitoring parameters;
and comparing and judging each second monitoring parameter with a corresponding time integral threshold value respectively to realize the early warning of the electrical safety hidden danger.
And respectively integrating the negative sequence power and the zero sequence power with time to obtain negative sequence electric energy and zero sequence electric energy of each time period, and using the negative sequence electric energy and the zero sequence electric energy as third monitoring parameters for analyzing and processing the asymmetric electrical insulation hidden danger of the motor.
Optionally, in step S2, the method specifically includes:
s021, respectively comparing the zero sequence current and the zero sequence current with corresponding protection thresholds;
s022, judging whether at least one parameter in the zero-sequence current and the zero-sequence voltage is larger than a corresponding protection threshold value; if yes, sending out a ground fault alarm; if not, the step S023 is carried out to judge whether the asymmetric short-circuit fault occurs:
s023, respectively comparing the negative sequence voltage and the negative sequence current with corresponding protection thresholds;
s024, judging whether at least one parameter in the negative sequence voltage and the negative sequence current is larger than a corresponding protection threshold value; if yes, an asymmetric short-circuit fault alarm is sent out; if not, then there is no asymmetric short fault.
Optionally, in step S1, the motor integrated protection process: including but not limited to motor start-up protection, locked rotor protection, overvoltage protection, undervoltage protection, overcurrent protection, and overheat protection.
Optionally, the method further comprises the following steps:
s4, respectively carrying out vector product on the negative sequence voltage and the negative sequence current and the zero sequence voltage and the zero sequence current in the first monitoring parameter to obtain negative sequence power and zero sequence power;
and respectively integrating the negative sequence power and the zero sequence power with time to obtain negative sequence electric energy and zero sequence electric energy of each time period, and using the negative sequence electric energy and the zero sequence electric energy as third monitoring parameters for analyzing and processing the asymmetric electrical insulation hidden danger of the motor.
Optionally, in step S4, the motor asymmetric electrical insulation hidden danger analysis processing includes the following steps:
s041, comparing and judging the negative sequence power and the zero sequence power with corresponding protection thresholds, and if the negative sequence power is greater than the corresponding protection thresholds and the zero sequence power is not greater than the corresponding protection thresholds, performing motor asymmetric short circuit hidden danger event early warning;
if only the zero sequence power is larger than the corresponding protection threshold value, early warning of the motor grounding hidden danger event is carried out;
and S042, analyzing the trend change of the third monitoring parameters in each time period along a time axis, and if the trend is obviously increased, carrying out early warning on the aggravation trend of the insulation hidden danger of the motor.
Optionally, the step S3 further includes refining the abnormal time period according to the time length, obtaining sub-integral monitoring parameters of each time sub-period in the abnormal time period, and determining one or a combination of the time node where the abnormality is located, the abnormality degree of each time sub-period, and the abnormality change trend according to each time sub-period and the sub-integral monitoring parameters corresponding to each time sub-period.
Optionally, in step S3, when the first monitoring parameter suddenly changes with respect to the protection threshold, from the sudden change beginning to the sudden change ending, the first monitoring parameter suddenly changes is integrated with respect to time to obtain a second monitoring parameter during the sudden change time period, and the second monitoring parameter during the sudden change time period is respectively compared with the corresponding time integration threshold by the early warning logic, so as to implement early warning of the electrical safety hazard.
The invention also provides an early warning type three-phase motor protection device applying the method, wherein the early warning type three-phase motor protection device comprises,
the signal acquisition module is used for acquiring each phase voltage and each phase current of the three-phase circuit of the motor;
the three-phase symmetric component calculation module is connected with the signal acquisition module and used for acquiring a first monitoring parameter of the three-phase motor, wherein the first monitoring parameter comprises: negative sequence voltage, zero sequence voltage, negative sequence current, and zero sequence current;
and the processing module is connected with the signal acquisition module and the three-phase symmetric component calculation module and is used for carrying out early warning logic processing on the first monitoring parameter, the second monitoring parameter and the third monitoring parameter so as to realize early warning of the electrical safety hidden danger.
Optionally, the signal acquisition module further includes:
the device comprises a voltage acquisition unit for acquiring zero-sequence voltage and a current acquisition unit for acquiring zero-sequence current, wherein the voltage acquisition unit is used for verifying the zero-sequence voltage calculated by the three-phase symmetric component calculation module, and the current acquisition unit is used for verifying the zero-sequence current calculated by the three-phase symmetric component calculation module.
Optionally, the signal acquisition module is further configured to acquire and obtain harmonic currents of each phase;
the harmonic current is obtained from the harmonic part of the current and is used as a monitoring parameter of the fault arc; and judging whether the harmonic current has intermittent generation characteristics, if so, determining that the fault electric arc hidden danger exists.
Optionally, the processing module includes an integral processing sub-module, a comparison sub-module and an early warning processing sub-module;
the integral processing submodule is connected with the output end of the acquisition module and is used for integrating the first monitoring parameter with time, and obtaining a second monitoring parameter and a third monitoring parameter and freezing and storing the second monitoring parameter and the third monitoring parameter;
the comparison submodule is connected with the output end of the integral processing submodule and is used for comparing the first monitoring parameter with a protection threshold value or comparing the first monitoring parameter with a time integral threshold value, comparing the third monitoring parameter with a corresponding set threshold value and outputting a result to the early warning processing submodule;
and the early warning processing submodule is connected with the output end of the comparison submodule and is used for processing the first monitoring parameter, the second monitoring parameter and the third monitoring parameter of the abnormal time period according to the result output by the comparison submodule and carrying out early warning on the electrical safety hidden danger.
The invention has the advantages of
1. Aiming at the characteristics of weak signals, slow change, large data quantity and the like of early hidden dangers in a motor mainly damaged by insulation, the invention adopts data optimization aggregation for integrating relevant weak signal data such as zero sequence, negative sequence and the like with time to obtain relevant time integral parameters of each time period, thereby forming new large-scale and strong signal data by optimizing and aggregating a large amount of weak signal data through data, greatly reducing the total data amount, improving the signal precision of the early and middle hidden dangers, and having remarkable effect on monitoring and early warning of the early and middle hidden dangers.
2. The method comprises the relevant time integral parameters of each time period with the sudden change start and stop as the boundary, and the sudden change time period integral parameters are used as the independent index parameters, so that the method is favorable for tracking the sudden change event process contained in the early hidden danger of the motor, and accurately mastering the hidden danger degree and the development trend of the relevant electric sudden change event. The time product classification parameters of the gradual change stage and the mutation stage are not distinguished, the respective characteristic information of the gradual change stage and the mutation stage is lacked, and the practical significance is greatly reduced.
3. The method can directly judge the existence of potential safety hazards of the abnormal time integral parameters which are larger than the threshold value. And for the abnormal time integral parameter smaller than the threshold, the sudden change time integral parameter is adopted, and the sudden change time period integral parameter with sudden change is found in the time period corresponding to the abnormal time integral parameter, so that the time for potential safety hazard occurrence can be further positioned, the component of the potential safety hazard of the motor can be found, and the judgment precision and accuracy are improved.
Drawings
Fig. 1 is a flowchart illustrating steps of an early warning type three-phase motor protection method according to the present invention;
fig. 2 is a flowchart illustrating a specific step of step S2 of the method for protecting a three-phase motor according to the present invention;
fig. 3 is a flowchart illustrating a specific step of step S4 of the method for protecting a three-phase motor according to the present invention;
fig. 4 is a logic block diagram of the early warning type three-phase motor protection device provided by the invention.
Detailed Description
The invention is further illustrated with reference to the following figures and examples.
Example 1:
referring to fig. 1 to 3, the embodiment provides an early warning type three-phase motor protection method, wherein the early warning type three-phase motor protection method includes the following steps:
and S1, collecting and calculating each phase voltage and each phase current of the three-phase motor power supply loop, and performing motor comprehensive protection calculation processing. Specifically, the judgment of the conventional motor protection function is performed according to each phase voltage and each phase current. Thus, the conventional motor protection function can be realized by the phase voltages and the phase currents. Optionally, in this step, the motor comprehensive protection process: including but not limited to motor start-up protection, locked rotor protection, overvoltage protection, undervoltage protection, overcurrent protection, and overheat protection.
S2, obtaining a first monitoring parameter through a symmetrical component method according to each phase voltage and each phase current, wherein the first monitoring parameter comprises: negative sequence current, zero sequence current, negative sequence voltage and zero sequence voltage of each phase.
S021 comparing the zero sequence voltage and current with the protection threshold,
s022, judging whether at least one parameter in the zero-sequence current and the zero-sequence voltage is larger than a corresponding protection threshold value; if yes, sending out a ground fault alarm; if not, the step S023 is carried out to judge whether the asymmetric short-circuit fault occurs:
s023, respectively comparing the negative sequence voltage and the negative sequence current with corresponding protection thresholds;
s024, judging whether at least one parameter in the negative sequence voltage and the negative sequence current is larger than a corresponding protection threshold value; if yes, an asymmetric short-circuit fault alarm is sent out; if not, then there is no asymmetric short fault.
And S3, integrating the first monitoring parameters with time to obtain time-integrated monitoring parameters of the first monitoring parameters in each time period, which are collectively called as second monitoring parameters.
And comparing and judging each second monitoring parameter with a corresponding time integral threshold value respectively to realize the early warning of the electrical safety hidden danger. When the circuit has hidden trouble, the corresponding time period is recorded as an abnormal time period.
Further, in step S3, when the first monitoring parameter suddenly changes with respect to the protection threshold, from the sudden change beginning to the sudden change ending, the first monitoring parameter suddenly changes is integrated with respect to time to obtain a second monitoring parameter during the sudden change time period, and the second monitoring parameter during the sudden change time period is compared with the corresponding time integration threshold for early warning, so as to achieve early warning of the electrical safety hazard.
Optionally, in step S3, the integration time period is refined according to the time length, so as to obtain sub-integration monitoring parameters of each time sub-period in the abnormal time period, and according to each time sub-period and the sub-integration monitoring parameters corresponding to each time sub-period, one or a combination of the time node where the abnormality is located, the abnormality degree and the abnormality change trend of each time sub-period is determined.
In specific implementation, the method further comprises step S4:
and S4, respectively carrying out vector product on the negative sequence voltage and the negative sequence current and the zero sequence voltage and the zero sequence current in the first monitoring parameter to obtain negative sequence power and zero sequence power.
And respectively integrating the negative sequence power and the zero sequence power with time to obtain negative sequence electric energy and zero sequence electric energy of each time period, wherein the negative sequence electric energy and the zero sequence electric energy are used as third monitoring parameters for analyzing and processing the asymmetric electrical insulation hidden danger of the motor.
And the third monitoring parameters comprise negative sequence electric energy and zero sequence electric energy parameters of each time period, the obtained third monitoring parameters are longitudinally compared, especially, if the zero sequence electric energy parameters of each time period in the non-fault operation state of the motor are obviously increased, the insulation reduction of the motor is judged, and corresponding early and middle insulation hidden danger development trend early warning is carried out.
In specific implementation, in steps S3 and S4, the integration characteristic of each time period is that the integration base time and the integration minimum duration can be set as required, and the integration time period is divided into one or more seconds, minutes, hours, days, and months. In steps S3 and S4, the comparison and judgment includes, but is not limited to, reporting high risk and serious risk when the second, minute and hour time integral parameters are greater than the corresponding threshold values, and reporting general middle and early risk when the daily integral parameters and monthly integral parameters are greater than the corresponding threshold values. Therefore, the type and the severity of the motor fault and the type and the severity of the hidden danger can be accurately judged.
In the scheme of the invention, the time integral threshold value of the unit hour time period is not a simple 60 times value of the time integral threshold value of the unit minute time period, and similarly, the time integral threshold value of the unit day time period is not a simple 24 times value of the time integral threshold value of the unit hour time period. In the scheme of the invention, the smaller the time integral threshold value of the unit time scale is, the more serious hidden danger condition is corresponding, and the larger the time integral threshold value of the unit time scale is, the more slight hidden danger condition is corresponding. The time integral threshold value of the unit hour time scale is obviously smaller than 60 times of the time integral threshold value of the unit minute time scale, and the time integral threshold value of the unit day time scale is obviously smaller than 24 times of the time integral threshold value of the unit hour time scale.
Preferably, in step S4, the motor asymmetric electrical insulation risk analysis process includes the following steps:
s041, comparing and judging the negative sequence power and the zero sequence power with corresponding time integral thresholds, if the negative sequence power is greater than the corresponding time integral thresholds and the zero sequence power is less than the corresponding time integral thresholds, judging that asymmetric short circuit hidden dangers occur, and early warning an asymmetric short circuit hidden danger event of the motor; and if the zero sequence power is greater than the corresponding time integral threshold value, whether the negative sequence power is greater than the corresponding time integral threshold value or not is judged, and the grounding hidden danger of the motor is pre-warned.
And S042, analyzing the trend change of the third monitoring parameter in each time period along a time axis, and if the trend is obviously increased, carrying out the trend early warning of the potential insulation hazard of the motor.
As will be understood by those skilled in the art, the first integral monitoring parameter is the integral of the first monitoring parameter in each time period, and different types of first monitoring parameters have different integral results for the same length of time period, and their corresponding time integral thresholds are different. The time integration threshold values of the same first monitoring parameter for the integration of different time periods are also different, that is, the first integration monitoring parameters corresponding to the time periods of different lengths are different, and therefore, the time integration threshold values corresponding to the time integration of the same first monitoring parameter for different time periods should also be different. Therefore, in the practical implementation process, the time integral threshold per time scale is generally preset, such as one minute, hour, day, etc., and the time integral threshold may be set as the product of the time duration corresponding to the time period and the time integral threshold per time scale.
Example 2
Referring to fig. 4, the present embodiment provides an early warning type three-phase motor protection device, wherein the early warning type three-phase motor protection device includes: the device comprises a signal acquisition module, a three-phase symmetric component calculation module and a processing module.
The signal acquisition module is used for acquiring each phase voltage and each phase current of the three-phase circuit of the motor.
The three-phase symmetric component calculation module is used for acquiring a first monitoring parameter of the three-phase motor, and the first monitoring parameter comprises: positive sequence voltage, negative sequence voltage, zero sequence voltage, positive sequence current, negative sequence current, and zero sequence current. In the field of alternating current electrical technology, the positive sequence, the negative sequence and the zero sequence are generated in order to analyze that when the system voltage and current are asymmetric, the asymmetric components of three phases are decomposed into symmetric components (positive sequence, negative sequence and homodromous zero sequence components). The symmetrical component method is to convert the asymmetrical three phases into symmetrical positive sequence, negative sequence and homodromous zero sequence. The ac power system is typically A, B, C three-phase, and the three-phase components of the power system, positive sequence, negative sequence and zero sequence, are determined according to the A, B, C three-phase sequence. Specifically, as follows, the following description will be given,
positive sequence: the phase A leads the phase B by 120 degrees, the phase B leads the phase C by 120 degrees, and the phase C leads the phase A by 120 degrees;
negative sequence: phase A is 120 degrees behind phase B, phase B is 120 degrees behind phase C, and phase C is 120 degrees behind phase A;
and (3) zero sequence: the ABC three phases are the same.
The positive sequence amplitude absolute values of all phases are equal, the negative sequence amplitude absolute values are equal, and the zero sequence amplitude absolute values are also equal. In this disclosure, unless otherwise specified, positive sequence current, negative sequence current, zero sequence current, positive sequence voltage, negative sequence voltage, and zero sequence voltage generally refer to the absolute values of the magnitudes of their respective parameters.
And the processing module is connected with the signal acquisition module and is used for carrying out early warning logic processing on the first monitoring parameter, the second monitoring parameter and the third monitoring parameter so as to realize early warning of the electrical safety hidden danger.
Optionally, the signal acquisition module further includes:
the voltage acquisition unit for acquiring zero sequence voltage and the current acquisition unit for acquiring zero sequence current realize the acquisition of zero sequence voltage and current through the mutual inductor as the supplement of a symmetrical component method. The voltage acquisition unit is used for verifying the zero sequence voltage calculated by the three-phase symmetric component calculation module, and the current acquisition unit is used for verifying the zero sequence current calculated by the three-phase symmetric component calculation module.
Specifically, the voltage acquisition unit is a voltage transformer PT, the current acquisition unit is a current transformer CT, and the processing module is integrated on a microcontroller chip dsPIC33FJ 256.
When the microcontroller is connected, the voltage transformers PT and the current transformers CT are connected to an ADC pin of the microcontroller chip dsPIC33FJ256 through corresponding acquisition and processing circuits, and the phase voltage A Ua, the phase voltage B Ub, the phase voltage C Uc, the phase current A Ia, the phase current B Ib and the phase current C Ic are obtained through the acquisition module 1 of the microcontroller.
Optionally, the signal acquisition module is further configured to acquire each phase of harmonic current to acquire an intermittent harmonic current.
The harmonic current is obtained from the harmonic part of the current and is used as a monitoring parameter of the fault arc; and judging whether the harmonic current has intermittent generation characteristics, if so, determining that the fault electric arc hidden danger exists.
Optionally, the processing module includes an integral processing sub-module, a comparison sub-module, and an early warning processing sub-module.
And the integral processing submodule is connected with the output end of the acquisition module and is used for integrating the first monitoring parameter with time, and obtaining a second monitoring parameter and a third monitoring parameter and freezing and storing the second monitoring parameter and the third monitoring parameter.
And the comparison submodule is connected with the output end of the integral processing submodule and is used for comparing the first monitoring parameter with a protection threshold value, comparing the second monitoring parameter with a time integral threshold value, comparing the third monitoring parameter with a corresponding set threshold value and outputting the result to the early warning processing submodule.
And the early warning processing submodule is connected with the output end of the comparison submodule and is used for processing the first monitoring parameter, the second monitoring parameter and the third monitoring parameter of the abnormal time period according to the result output by the comparison submodule and carrying out early warning on the electrical safety hidden danger.
In specific implementation, the early warning type three-phase motor protection device further comprises a real-time clock module, the real-time clock module is connected with the integral processing submodule, and the real-time clock module is used for generating a collection and integral time reference.
One of ordinary skill in the art will appreciate that all or some of the steps in the methods, systems, and functional modules/sub-modules in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof.
In a hardware implementation, the division between functional modules/sub-modules referred to in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the physical components may be implemented as hardware or as integrated circuits, such as application specific integrated circuits.
The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, and are not to be construed as limiting the scope of the invention. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present invention are intended to be within the scope of the claims.
Claims (9)
1. An early warning type three-phase motor protection method is characterized by comprising the following steps: the early warning type three-phase motor protection method comprises the following steps:
s1, collecting and calculating each phase voltage and current of the three-phase power supply loop of the motor, and carrying out comprehensive protection processing on the motor;
s2, obtaining a first monitoring parameter according to each phase voltage and each phase current, wherein the first monitoring parameter comprises: each phase of negative sequence current, zero sequence current, negative sequence voltage and zero sequence voltage;
comparing the zero sequence voltage and the zero sequence current with corresponding protection thresholds respectively, and judging whether a ground fault occurs;
if the ground fault is judged not to occur, the negative sequence voltage and the negative sequence current are respectively compared with corresponding protection thresholds, and whether an asymmetric short-circuit fault occurs or not is judged according to a comparison result;
s3, integrating the first monitoring parameters with time to obtain integrated monitoring parameters of the first monitoring parameters in each time period, which are collectively called as second monitoring parameters;
comparing and judging each second monitoring parameter with a corresponding time integral threshold value respectively to realize early warning of the electrical safety hidden danger;
in step S2, the method specifically includes:
s021, respectively comparing the zero-sequence current and the zero-sequence voltage with corresponding protection thresholds;
s022, judging whether at least one parameter in the zero-sequence current and the zero-sequence voltage is larger than a corresponding protection threshold value; if yes, sending out a ground fault alarm; if not, the step S023 is carried out to judge whether the asymmetric short-circuit fault occurs:
s023, respectively comparing the negative sequence voltage and the negative sequence current with corresponding protection thresholds;
s024, judging whether at least one parameter in the negative sequence voltage and the negative sequence current is larger than a corresponding protection threshold value; if yes, an asymmetric short-circuit fault alarm is sent out; if not, then there is no asymmetric short fault.
2. The early warning type three-phase motor protection method according to claim 1, characterized in that: in step S1, the motor integrated protection process: including but not limited to motor start-up protection, locked rotor protection, overvoltage protection, undervoltage protection, overcurrent protection, and overheat protection.
3. The early warning type three-phase motor protection method according to claim 1, characterized in that: further comprising the steps of:
s4, respectively carrying out vector product on the negative sequence voltage and the negative sequence current and the zero sequence voltage and the zero sequence current in the first monitoring parameter to obtain negative sequence power and zero sequence power;
and respectively integrating the negative sequence power and the zero sequence power with time to obtain negative sequence electric energy and zero sequence electric energy of each time period, and using the negative sequence electric energy and the zero sequence electric energy as third monitoring parameters for analyzing and processing the asymmetric electrical insulation hidden danger of the motor.
4. The early warning type three-phase motor protection method according to claim 3, characterized in that: in step S4, the motor asymmetric electrical insulation hidden danger analysis processing includes the following steps:
s041, comparing and judging the negative sequence power and the zero sequence power with corresponding protection thresholds, and if the negative sequence power is greater than the corresponding protection thresholds and the zero sequence power is not greater than the corresponding protection thresholds, performing motor asymmetric short circuit hidden danger event early warning;
if only the zero sequence power is larger than the corresponding protection threshold value, early warning of the motor grounding hidden danger event is carried out;
and S042, analyzing the trend change of the third monitoring parameters in each time period along a time axis, and if the trend is obviously increased, carrying out early warning on the aggravation trend of the insulation hidden danger of the motor.
5. The early warning type three-phase motor protection method according to any one of claims 1 to 4, characterized in that: step S3 further includes refining the abnormal time segment according to the time length, obtaining the sub-integral monitoring parameters of each time sub-segment in the abnormal time segment, and determining one or a combination of the time node where the abnormality is located, the abnormal degree and the abnormal change trend of each time sub-segment according to each time sub-segment and the sub-integral monitoring parameters corresponding to each time sub-segment.
6. The early warning type three-phase motor protection method according to any one of claims 1 to 4, characterized in that: in step S3, when the first monitoring parameter suddenly changes with respect to the protection threshold, from the sudden change beginning to the sudden change ending, the first monitoring parameter suddenly changes is integrated with respect to time to obtain a second monitoring parameter suddenly changing in time period, and the second monitoring parameter suddenly changing in time period is compared with the corresponding time integration threshold respectively to implement early warning of the electrical safety hazard.
7. An early warning type three-phase motor protection device to which the early warning type three-phase motor protection method according to any one of claims 1 to 6 is applied, characterized in that: the early-warning type three-phase motor protection device comprises,
the signal acquisition module is used for acquiring each phase voltage and each phase current of the three-phase circuit of the motor;
the three-phase symmetric component calculation module is connected with the signal acquisition module and used for acquiring a first monitoring parameter of the three-phase motor, wherein the first monitoring parameter comprises: negative sequence voltage, zero sequence voltage, negative sequence current, and zero sequence current;
the processing module is connected with the signal acquisition module and the three-phase symmetric component calculation module and is used for performing early warning logic processing on the first monitoring parameter, the second monitoring parameter and the third monitoring parameter so as to realize early warning of electrical safety hazards;
the processing module comprises an integral processing submodule, a comparison submodule and an early warning processing submodule;
the integral processing submodule is connected with the output end of the three-phase symmetric component calculation module and is used for integrating the first monitoring parameter with time, obtaining a second monitoring parameter and a third monitoring parameter and freezing and storing the second monitoring parameter and the third monitoring parameter;
the comparison submodule is connected with the output end of the integral processing submodule and is used for comparing the first monitoring parameter with a protection threshold value, comparing the second monitoring parameter with a time integral threshold value, comparing the third monitoring parameter with a corresponding set threshold value and outputting a result to the early warning processing submodule;
the early warning processing submodule is connected with the output end of the comparison submodule and is used for processing the first monitoring parameter, the second monitoring parameter and the third monitoring parameter in an abnormal time period according to the result output by the comparison submodule and carrying out early warning on the electric potential safety hazard;
the comparison sub-module is further configured to: respectively comparing the zero-sequence current and the zero-sequence voltage with corresponding protection thresholds; judging whether at least one parameter in the zero-sequence current and the zero-sequence voltage is larger than a corresponding protection threshold value; if yes, sending out a ground fault alarm; if not, comparing the negative sequence voltage and the negative sequence current with corresponding protection thresholds respectively; judging whether at least one parameter in the negative sequence voltage and the negative sequence current is larger than a corresponding protection threshold value; if yes, an asymmetric short-circuit fault alarm is sent out; if not, then there is no asymmetric short fault.
8. The early warning type three-phase motor protection device according to claim 7, characterized in that: the signal acquisition module further comprises:
the device comprises a voltage acquisition unit for acquiring zero-sequence voltage and a current acquisition unit for acquiring zero-sequence current, wherein the voltage acquisition unit is used for verifying the zero-sequence voltage calculated by the three-phase symmetric component calculation module, and the current acquisition unit is used for verifying the zero-sequence current calculated by the three-phase symmetric component calculation module.
9. The early warning type three-phase motor protection device according to claim 7, characterized in that: the signal acquisition module is also used for acquiring and obtaining harmonic currents of each phase;
the harmonic current is obtained from the harmonic part of the current and is used as a monitoring parameter of the fault arc; and judging whether the harmonic current has intermittent generation characteristics, if so, determining that the fault electric arc hidden danger exists.
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