CN114879028B - Method, system and equipment for evaluating minimum input time of switching-on resistance of circuit breaker - Google Patents
Method, system and equipment for evaluating minimum input time of switching-on resistance of circuit breaker Download PDFInfo
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Abstract
The invention relates to the technical field of excitation inrush current suppression, and discloses a method, a system and equipment for evaluating minimum input time of a switching-on resistor of a circuit breaker. The method comprises the steps of determining steady-state magnetic flux of a transformer corresponding to a circuit breaker and a closing angle of an auxiliary contact in the circuit breaker when the auxiliary contact is closed, further calculating a minimum breaking angle of excitation surge current according to the steady-state magnetic flux and the closing angle, and finally evaluating minimum input time of a closing resistor carried by the circuit breaker according to the minimum breaking angle and the closing angle. The minimum input time of the switching-on resistor is determined according to the minimum breaking angle of the excitation surge current and the switching-on angle of the auxiliary contact, and compared with the mode of setting the minimum input time of the switching-on resistor according to experience parameters in the prior art, the invention can more effectively inhibit the excitation surge current.
Description
Technical Field
The invention relates to the technical field of excitation inrush current suppression, in particular to a method, a system and equipment for evaluating minimum input time of a switching-on resistor of a circuit breaker.
Background
The magnetizing inrush current is an inrush current generated in a coil of an empty transformer when the transformer is put into operation due to the nonlinear saturation characteristic of the transformer core and the influence of residual magnetic flux in the core before the transformer is put into operation. The amplitude of the impulse current is more than 20 times of the no-load current, which may cause damage to an alternating current filter and a transformer, thereby causing distortion of alternating voltage and current and seriously jeopardizing the safe operation of the system.
At present, a breaker with a switching-on resistor is mainly adopted to weaken exciting inrush current generated when an idle transformer is put into operation, and the switching-on resistor is put into an electric loop to reduce the increase of magnetic flux, so that the magnitude of the exciting inrush current is restrained, and the switching-on resistor is withdrawn after being put into operation for a certain time. In theory, the longer the switching-on resistor is put in, the more excitation surge current can be reduced, however, the longer the switching-on resistor is put in, the higher the requirements on the quality of the switching-on resistor and the breaker per se are, and the higher the cost is. Therefore, it is necessary to reasonably determine the minimum time taken for the closing resistance.
In the prior art, the minimum input time of the switching-on resistor is set according to experience parameters, however, research shows that the setting mode can not well inhibit excitation surge current after the switching-on resistor is input.
Disclosure of Invention
The invention provides a method, a system and equipment for evaluating the minimum input time of a switching-on resistor of a circuit breaker, and solves the technical problem that the excitation surge current cannot be effectively restrained after the switching-on resistor is input by the conventional determination mode of the minimum input time of the switching-on resistor.
The invention provides a method for evaluating minimum input time of a closing resistor of a circuit breaker, which comprises the following steps:
determining steady-state magnetic flux of a transformer corresponding to a circuit breaker and a closing angle of an auxiliary contact in the circuit breaker when the auxiliary contact is closed;
calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle;
And evaluating the minimum input time of the switching-on resistor of the circuit breaker according to the minimum breaking angle and the switching-on angle.
According to one implementation manner of the first aspect of the present invention, the determining the steady-state magnetic flux of the transformer corresponding to the circuit breaker includes:
And obtaining the rated voltage and the steady-state inductance of the transformer, determining the resistance value of the closing resistor, and calculating the steady-state magnetic flux of the transformer according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance.
According to one implementation manner of the first aspect of the present invention, the calculating the steady-state magnetic flux of the transformer according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance includes:
The steady state flux of the transformer is calculated as:
Where Φ m denotes steady-state magnetic flux of the transformer, U m is rated voltage of the transformer, R is resistance of the closing resistor, L is steady-state inductance, and ω is angular speed of operation of the alternator.
According to one implementation manner of the first aspect of the present invention, the calculating a minimum break angle of the excitation surge current according to the steady-state magnetic flux and the closing angle includes:
The minimum break angle of the excitation surge current is calculated as follows:
In the formula, theta min represents the minimum break angle of excitation surge current, phi m is steady-state magnetic flux of the transformer, phi sat is saturation magnetic flux of the transformer, and alpha is the auxiliary contact closing angle.
According to one implementation manner of the first aspect of the present invention, the calculating the minimum break angle of the excitation surge current includes:
And taking the steady-state magnetic flux of the transformer as 1.15pu when calculating the minimum break angle of the excitation surge current.
According to one implementation manner of the first aspect of the present invention, the estimating the minimum input time of the closing resistance of the circuit breaker according to the minimum breaking angle and the closing angle includes:
when the closing angle is in the range of [0, 90 ° ], the minimum input time of the closing resistance is evaluated according to the following formula:
when the closing angle is within the range of (90 °,180 ° ], the minimum input time of the closing resistance is evaluated according to the following equation:
In the formula, T represents the minimum input time of the switching-on resistor, theta min is the minimum break angle of the excitation surge current, alpha is the auxiliary contact switching-on angle, and T δ is the time limit value of the switching-on resistor input.
According to one implementation manner of the first aspect of the present invention, the estimating the minimum input time of the closing resistance of the circuit breaker according to the minimum breaking angle and the closing angle further includes:
and setting the time limit value of the switching-on resistor to be 20ms.
The second aspect of the invention provides a minimum input time evaluation system for a closing resistor of a circuit breaker, comprising:
The determining module is used for determining steady-state magnetic flux of a transformer corresponding to the circuit breaker and a closing angle when an auxiliary contact in the circuit breaker is closed;
The calculation module is used for calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle;
And the evaluation module is used for evaluating the minimum input time of the switching-on resistance of the circuit breaker according to the minimum breaking angle and the switching-on angle.
According to one manner in which the second aspect of the present invention can be implemented, the determining module includes:
and the steady-state magnetic flux determining unit is used for obtaining the rated voltage and the steady-state inductance of the transformer, determining the resistance value of the closing resistor and calculating the steady-state magnetic flux of the transformer according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance.
According to one possible manner of the second aspect of the present invention, the steady-state magnetic flux determining unit is specifically configured to:
The steady state flux of the transformer is calculated as:
Where Φ m denotes steady-state magnetic flux of the transformer, U m is rated voltage of the transformer, R is resistance of the closing resistor, L is steady-state inductance, and ω is angular speed of operation of the alternator.
According to one manner in which the second aspect of the present invention can be implemented, the computing module includes:
A calculation unit for calculating a minimum break angle of the excitation surge current according to the following formula:
In the formula, theta min represents the minimum break angle of excitation surge current, phi m is steady-state magnetic flux of the transformer, phi sat is saturation magnetic flux of the transformer, and alpha is the auxiliary contact closing angle.
According to one possible implementation manner of the second aspect of the present invention, the computing unit is specifically configured to:
And taking the steady-state magnetic flux of the transformer as 1.15pu when calculating the minimum break angle of the excitation surge current.
According to one implementation manner of the second aspect of the present invention, the evaluation module includes:
A first evaluation unit, configured to evaluate a minimum input time of the closing resistance according to the following formula when the closing angle is in a range of [0, 90 ° ]:
a second evaluation unit for evaluating the minimum input time of the closing resistance according to the following formula when the closing angle is within the range of (90 °,180 °):
In the formula, T represents the minimum input time of the switching-on resistor, theta min is the minimum break angle of the excitation surge current, alpha is the auxiliary contact switching-on angle, and T δ is the time limit value of the switching-on resistor input.
According to one implementation manner of the second aspect of the present invention, the evaluation module further includes:
And the setting unit is used for setting the time limit value of the switching-on resistance input to be 20ms.
The third aspect of the invention provides a minimum input time assessment device for a closing resistor of a circuit breaker, comprising:
a memory for storing instructions; the instruction is used for realizing the minimum input time assessment method for the switching-on resistance of the circuit breaker in the mode which can be realized according to any one of the above modes;
And the processor is used for executing the instructions in the memory.
A fourth aspect of the present invention is a computer-readable storage medium having a computer program stored thereon, which when executed by a processor, implements the method for evaluating a minimum input time for a closing resistance of a circuit breaker according to any one of the modes described above.
From the above technical scheme, the invention has the following advantages:
The method comprises the steps of determining steady-state magnetic flux of a transformer corresponding to a circuit breaker and a closing angle of an auxiliary contact in the circuit breaker when the auxiliary contact is closed, further calculating a minimum breaking angle of excitation surge current according to the steady-state magnetic flux and the closing angle, and finally evaluating minimum input time of a closing resistor carried by the circuit breaker according to the minimum breaking angle and the closing angle; the minimum input time of the switching-on resistor is determined according to the minimum breaking angle of the excitation surge current and the switching-on angle of the auxiliary contact, and compared with the mode of setting the minimum input time of the switching-on resistor according to experience parameters in the prior art, the invention can more effectively inhibit the excitation surge current.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a schematic diagram of various curves of transient and steady state magnetic fluxes taking into account initial state magnetic fluxes provided by an alternative embodiment of the present invention;
FIG. 2 is a schematic diagram of an approximate forward magnetization curve of a transformer according to an alternative embodiment of the present invention;
fig. 3 is a flowchart of a method for evaluating minimum throw-in time of a switching-on resistance of a circuit breaker according to an alternative embodiment of the present invention;
FIG. 4 is a schematic diagram of a forward saturated excitation surge current waveform with a closing resistor according to an alternative embodiment of the present invention;
FIG. 5 is a schematic diagram of a magnetizing inrush current waveform with switching on resistance in reverse saturation according to an alternative embodiment of the present invention;
FIG. 6 is a schematic diagram showing a relationship between a closing angle of an auxiliary contact and a minimum input time of a closing resistor when the closing angle of the auxiliary contact is in a range of 0-180 degrees according to an alternative embodiment of the present invention;
Fig. 7 is a block diagram illustrating a structural connection of a minimum throw-in time evaluation system for a closing resistance of a circuit breaker according to an alternative embodiment of the present invention.
Reference numerals:
1-a determination module; 2-a calculation module; 3-an evaluation module.
Detailed Description
The embodiment of the invention provides a method, a system and equipment for evaluating minimum input time of a switching-on resistor of a circuit breaker, which are used for solving the technical problem that excitation surge current cannot be effectively restrained after the switching-on resistor is input in a current determination mode of the minimum input time of the switching-on resistor.
In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present invention, but not all embodiments of the present invention. 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.
The method, the system and the equipment for evaluating the minimum input time of the switching-on resistance of the circuit breaker are used for evaluating the minimum input time of the switching-on resistance (namely the minimum input time of the switching-on resistance) required by suppressing excitation surge current. The magnetizing inrush current is an inrush current generated in a coil of an empty transformer when the transformer is put into operation due to the nonlinear saturation characteristic of the transformer core and the influence of residual magnetic flux in the core before the transformer is put into operation.
At present, a single-phase transformer is generally selected as a large-capacity transformer, and in order to better explain the principle and effect of suppressing the excitation surge current, the single-phase transformer is taken as an example to explain the generation principle of the excitation surge current and the interruption angle of the excitation surge current.
When the closing resistance is not considered, the relation between the voltage and the magnetic flux of the transformer satisfies:
where u is the voltage of the transformer and phi is the magnetic flux.
Assuming that the transformer is switched on at the moment 0 of the positive zero crossing point of a certain alternating current voltage, the voltage waveform is sine wave, and the voltage expression is brought into the formula (1), so that the voltage is obtained:
φ＝-Φm cos(ωt+α)+Φ(0) (2)
Wherein alpha is an auxiliary contact closing angle, phi m is steady-state magnetic flux of the transformer, namely magnetic flux generated when the transformer operates at rated voltage, and phi (0) is initial magnetic flux at 0 moment;
The magnetic flux cannot be suddenly changed, and the following can be obtained:
Φ(0)＝Φm cos(α)+Φr (3)
Where Φ r represents the remanence of the transformer.
Assuming that the circuit breaker studied in the present application is equipped with a phase-selecting switching-on/off device, it is possible to switch on/off at an ideal angle, and at this time, the influence of remanence, Φ r =0, is not considered.
As shown in fig. 1, curves of transient magnetic flux and steady magnetic flux considering initial state magnetic flux are listed in fig. 1, where a is a steady magnetic flux curve, a + is a transient magnetic flux curve considering forward initial state magnetic flux, a - is a transient magnetic flux curve considering reverse initial state magnetic flux, Φ sat represents saturation magnetic flux of the transformer, and θ min represents a minimum break angle of excitation inrush current. The value range of the saturation magnetic flux is generally 1.15 to 1.4. The transformer generally does not exceed the steady state flux during steady operation, but Φ (0)＞Φsat during severe angle closing. It can be seen that saturation is most severe at the break angle θ=pi of the magnetizing inrush current in one cycle, and when Φ (0) +.0, the transient magnetic flux curve has a bias of Φ (0). At the time of forward saturation, when ωt=θ min, the following is satisfied:
Φsat＝-Φm cos(ωt+α)+Φ(0) (4)。
as shown in fig. 2, when the iron core is not saturated, the slope of the magnetization curve is larger, the current is approximately 0, the slope K is smaller after the magnetic flux reaches more than phi sat, the current is rapidly increased, the exciting current is formed, and the process of reverse magnetization is similar.
From fig. 1 and 2, it is possible to obtain:
Wherein, I m is the peak value of excitation surge current, and the corresponding magnetic flux is phi m cos(α)+Φm.
In one period (0, 2 pi), its forward saturated excitation surge current can be expressed as:
Wherein i u+ represents a forward saturated excitation surge current;
reverse saturation excitation surge can be expressed as:
Where i u- denotes a reverse saturation excitation surge current.
Obtainable according to formula (5):
Referring to fig. 3, fig. 3 shows a flowchart of a method for evaluating minimum input time of a switching-on resistance of a circuit breaker according to an embodiment of the present invention.
The method for evaluating the minimum input time of the switching-on resistor of the circuit breaker provided by the embodiment of the invention comprises the steps S1-S3.
And S1, determining steady-state magnetic flux of a transformer corresponding to the circuit breaker and a closing angle of an auxiliary contact in the circuit breaker during closing.
The transformer corresponding to the circuit breaker, namely the transformer applying the circuit breaker to restrain the exciting surge. In this embodiment, the circuit breaker includes a main contact, an auxiliary contact and a closing resistor, where the auxiliary contact is connected in series with the closing resistor and then connected in parallel with the main contact.
As one implementation manner, when determining the steady-state magnetic flux of the transformer corresponding to the circuit breaker, the rated voltage and the steady-state inductance of the transformer can be obtained, the resistance value of the closing resistor is determined, and then the steady-state magnetic flux of the transformer is calculated according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance.
As a specific embodiment, the steady state magnetic flux of the transformer is calculated according to the following formula:
Where Φ m denotes steady-state magnetic flux of the transformer, U m is rated voltage of the transformer, R is resistance of the closing resistor, L is steady-state inductance, and ω is angular speed of operation of the alternator.
And S2, calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle.
According to the generation principle of the exciting current and the description of the breaking angle of the exciting current, the minimum breaking angle of the exciting current can be deduced from the formulas (3) and (4), and the calculation formula of the minimum breaking angle of the exciting current is as follows:
In the formula, theta min represents the minimum break angle of excitation surge current, phi m is steady-state magnetic flux of the transformer, phi sat is saturation magnetic flux of the transformer, and alpha is the auxiliary contact closing angle.
The saturation magnetic flux is generally in the range of 1.15 to 1.4, and in this embodiment, the steady-state magnetic flux of the transformer is preferably 1.15pu when calculating the minimum break angle of the magnetizing inrush current.
In the embodiment of the invention, a calculation formula of the minimum break angle of the excitation surge current is provided, the calculation formula accords with the generation principle of the excitation surge current, and the minimum break angle of the excitation surge current can be accurately and rapidly obtained according to the calculation formula.
And S3, evaluating the minimum input time of the switching-on resistor of the circuit breaker according to the minimum breaking angle and the switching-on angle.
From the above description of the generation principle of the excitation surge and the break angle of the excitation surge, the waveforms of the excitation surge saturated in the forward direction with the closing resistor may be shown in fig. 4, and the waveforms of the excitation surge saturated in the reverse direction with the closing resistor may be shown in fig. 5. In fig. 4 and 5, the 0 time is the time corresponding to the positive zero crossing of the ac voltage. The peak excitation current is related to the steady-state flux amplitude, the saturation flux, the auxiliary contact closing angle, and the magnetization curve slope, which are related to the transformer characteristics. As is clear from equations (7), (8) and (9), when the auxiliary contact closing angle α is n×pi, n=0, 1 and 2, the peak value of the magnetizing inrush current will be the maximum value when the transformer is charged in no-load. In addition, the closing angle alpha of the auxiliary contact is in the range of (0, pi), and the excitation surge current amplitude is symmetrically distributed by taking alpha=pi/2 as the center.
It can be seen that the excitation surge waveform is completely deviated from one side of the time axis and is intermittent, and the width of the waveform discontinuity is referred to as the excitation surge break angle θ, and θ=2θ min. The more severe the transformer saturation, the smaller the magnetizing inrush current break angle θ, which is characterized by a larger magnetizing inrush current. The excitation surge interruption angle θ is also symmetrically distributed with α=pi/2 as the center.
According to the analysis, the circuit breaker applies a closing resistor after the converter transformer flows through the current, so that the steady-state component of the exciting inrush current can be reduced. According to equations (6) and (7), the closing resistor is turned on at the closing angle α, and the exit time is required to be in the section of the saturation excitation surge current i u not equal to 0, so that the steady-state magnetic flux can be weakened. According to equation (8), after the rated magnetic flux is reduced, the peak value of the excitation inrush current is also reduced. Thus, to act to attenuate the magnetizing inrush current, in one possible way, when the closing angle is in the range of [0, 90 ° ], the minimum input time of the closing resistance is estimated according to the following equation:
And when the closing angle is within the range of (90 °,180 ° ], the minimum input time of the closing resistance is estimated according to the following formula:
In the formula, T represents the minimum input time of the switching-on resistor, theta min is the minimum break angle of the excitation surge current, alpha is the auxiliary contact switching-on angle, and T δ is the time limit value of the switching-on resistor input.
Wherein, as a preference, T δ = 20ms is set.
As shown in fig. 4 and 5, the minimum switching-in time of the switching-on resistor is estimated according to the formulas (11) and (12) in the present embodiment, so that the switching-on resistor can play a role of weakening the excitation surge current after being switched on.
As an example, when calculating the minimum breaking angle of the excitation surge current, Φ m＝1.1pu,Φsat =1.15 pu is taken, and according to formulas (10), (11) and (12), the corresponding relation between the auxiliary contact closing angle and the minimum input time of the closing resistance when the auxiliary contact closing angle is in the range of 0-180 ° is calculated as shown in fig. 6, wherein T δ =20 ms is set during calculation. As can be seen from fig. 6, if the switching-on resistor can weaken the exciting inrush current at different auxiliary contact switching-on angles, the switching-on time cannot be lower than 12.81ms, and the longer the switching-on time, the better the weakening of the exciting inrush current. And as can be seen from fig. 6, when the switching-on angle is 90-180 degrees, the switching-on angle is reverse saturation, and the time of excitation surge current is [ (pi+θ min -alpha)/2pi ] ×20ms, which is later than that of forward saturation, so that the weakening effect of the switching-on resistor on the excitation surge current of reverse saturation is lower than that of forward saturation under the condition of certain switching-on time of the switching-on resistor.
The invention also provides a system for evaluating the minimum input time of the switching-on resistance of the circuit breaker, which can be used for realizing the method for evaluating the minimum input time of the switching-on resistance of the circuit breaker according to any one of the embodiments.
Referring to fig. 7, fig. 7 shows a block diagram of structural connection of a minimum input time evaluation system for switching-on resistance of a circuit breaker according to an embodiment of the invention.
The embodiment of the invention provides a minimum input time evaluation system for a closing resistor of a circuit breaker, which comprises the following steps:
the determining module 1 is used for determining steady-state magnetic flux of a transformer corresponding to the circuit breaker and a closing angle when an auxiliary contact in the circuit breaker is closed;
the calculating module 2 is used for calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle;
and the evaluation module 3 is used for evaluating the minimum input time of the switching-on resistance of the circuit breaker according to the minimum breaking angle and the switching-on angle.
In one possible implementation, the determining module 1 includes:
and the steady-state magnetic flux determining unit is used for obtaining the rated voltage and the steady-state inductance of the transformer, determining the resistance value of the closing resistor and calculating the steady-state magnetic flux of the transformer according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance.
In one possible implementation, the steady state magnetic flux determining unit is specifically configured to:
The steady state flux of the transformer is calculated as:
Where Φ m denotes steady-state magnetic flux of the transformer, U m is rated voltage of the transformer, R is resistance of the closing resistor, L is steady-state inductance, and ω is angular speed of operation of the alternator.
In one possible implementation, the computing module 2 includes:
A calculation unit for calculating a minimum break angle of the excitation surge current according to the following formula:
In the formula, theta min represents the minimum break angle of excitation surge current, phi m is steady-state magnetic flux of the transformer, phi sat is saturation magnetic flux of the transformer, and alpha is the auxiliary contact closing angle.
In one possible implementation, the computing unit is specifically configured to:
And taking the steady-state magnetic flux of the transformer as 1.15pu when calculating the minimum break angle of the excitation surge current.
In one possible implementation, the evaluation module 3 comprises:
A first evaluation unit, configured to evaluate a minimum input time of the closing resistance according to the following formula when the closing angle is in a range of [0, 90 ° ]:
a second evaluation unit for evaluating the minimum input time of the closing resistance according to the following formula when the closing angle is within the range of (90 °,180 °):
In the formula, T represents the minimum input time of the switching-on resistor, theta min is the minimum break angle of the excitation surge current, alpha is the auxiliary contact switching-on angle, and T δ is the time limit value of the switching-on resistor input.
In one possible implementation, the evaluation module 3 further comprises:
And the setting unit is used for setting the time limit value of the switching-on resistance input to be 20ms.
The invention also provides a minimum input time assessment device for the closing resistance of the circuit breaker, which comprises the following components:
A memory for storing instructions; the instruction is used for realizing the minimum input time assessment method for the switching-on resistance of the circuit breaker according to any one of the embodiments;
And the processor is used for executing the instructions in the memory.
The invention also provides a computer readable storage medium, wherein the computer readable storage medium is stored with a computer program, and the computer program realizes the minimum input time assessment method for the closing resistance of the circuit breaker according to any one of the embodiments when being executed by a processor.
According to the embodiment of the invention, the minimum input time of the switching-on resistor is determined according to the minimum breaking angle of the excitation surge current and the switching-on angle of the auxiliary contact, and compared with the mode of setting the minimum input time of the switching-on resistor according to experience parameters in the prior art, the excitation surge current can be more effectively restrained.
It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described system, apparatus and module may refer to corresponding procedures in the foregoing method embodiments, and specific beneficial effects of the above-described system, apparatus and module may refer to corresponding beneficial effects in the foregoing method embodiments, which are not repeated herein.
In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interface, indirect coupling or communication connection of devices or modules, electrical, mechanical, or other form.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed over a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist alone physically, or two or more modules may be integrated into one module. The integrated modules may be implemented in hardware or in software functional modules.
The integrated modules, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. The method for evaluating the minimum input time of the closing resistance of the circuit breaker is characterized by comprising the following steps of:
determining steady-state magnetic flux of a transformer corresponding to a circuit breaker and a closing angle of an auxiliary contact in the circuit breaker when the auxiliary contact is closed;
calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle;
Evaluating the minimum input time of a closing resistor carried by the circuit breaker according to the minimum breaking angle and the closing angle;
The minimum input time of the closing resistance carried by the breaker is estimated according to the minimum breaking angle and the closing angle, and the method comprises the following steps:
When the closing angle is at And when the range is over, evaluating the minimum input time of the closing resistor according to the following formula:
；
When the closing angle is at And when the switching resistance is within the range, evaluating the minimum input time of the switching resistance according to the following formula:
；
In the method, in the process of the invention, The minimum input time of the closing resistance is represented,For the minimum break angle of the excitation surge,In order to assist the closing angle of the contacts,The time limit value for the switching-on resistor.
2. The method for evaluating the minimum throw-in time of a closing resistor of a circuit breaker according to claim 1, wherein determining the steady-state magnetic flux of a transformer corresponding to the circuit breaker comprises:
And obtaining the rated voltage and the steady-state inductance of the transformer, determining the resistance value of the closing resistor, and calculating the steady-state magnetic flux of the transformer according to the resistance value of the closing resistor, the rated voltage and the steady-state inductance.
3. The method for evaluating the minimum throw-in time of a closing resistor of a circuit breaker according to claim 2, wherein the calculating the steady-state magnetic flux of the transformer from the resistance value of the closing resistor, the rated voltage and the steady-state inductance comprises:
The steady state flux of the transformer is calculated as:
；
In the method, in the process of the invention, Indicating the steady state magnetic flux of the transformer,For the rated voltage of the transformer,Is the resistance value of the closing resistor,Is an inductance in a steady state and,Is the angular velocity at which the alternator operates.
4. The method for evaluating minimum throw-in time of a closing resistor of a circuit breaker according to claim 1, wherein the calculating a minimum break angle of a magnetizing inrush current from the steady state magnetic flux and the closing angle comprises:
The minimum break angle of the excitation surge current is calculated as follows:
；
In the method, in the process of the invention, Represents the minimum break angle of the excitation surge,Is the steady-state magnetic flux of the transformer,Is the saturation magnetic flux of the transformer,The auxiliary contact closing angle is obtained.
5. The method for evaluating minimum throw-in time of a closing resistor of a circuit breaker according to claim 4, wherein the calculating a minimum break angle of a magnetizing inrush current comprises:
the value of steady-state magnetic flux of the transformer is taken as when the minimum break angle of the excitation surge current is calculated 。
6. The method for evaluating the minimum throw-in time of a closing resistance of a circuit breaker according to claim 1, wherein the evaluating the minimum throw-in time of the closing resistance of the circuit breaker based on the minimum break angle and the closing angle further comprises:
and setting the time limit value of the switching-on resistor to be 20ms.
7. The minimum input time evaluation system of circuit breaker closing resistance is characterized by comprising:
The determining module is used for determining steady-state magnetic flux of a transformer corresponding to the circuit breaker and a closing angle when an auxiliary contact in the circuit breaker is closed;
The calculation module is used for calculating the minimum breaking angle of the excitation surge current according to the steady-state magnetic flux and the closing angle;
And the evaluation module is used for evaluating the minimum input time of the switching-on resistance of the circuit breaker according to the minimum breaking angle and the switching-on angle.
8. A circuit breaker closing resistance minimum throw-in time assessment apparatus, comprising:
A memory for storing instructions; the instructions are used for realizing the minimum input time assessment method for the switching-on resistance of the circuit breaker according to any one of claims 1-6;
And the processor is used for executing the instructions in the memory.
9. A computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and when executed by a processor, the computer program implements the circuit breaker closing resistance minimum throw-in time evaluation method according to any one of claims 1 to 6.
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| US6472877B1 (en) * | 1997-06-25 | 2002-10-29 | Chevron U.S.A., Inc. | Method and apparatus for measuring the opening time of a medium voltage air circuit breaker |
| US6965238B2 (en) * | 2003-03-31 | 2005-11-15 | General Electric Company | Methods and apparatus for analyzing high voltage circuit breakers |
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| CN107884707B (en) * | 2017-09-30 | 2018-12-21 | 杨启蓓 | High-voltage circuit-breaker switching on-off time on-Line Monitor Device and method |
| CN110932246A (en) * | 2015-09-18 | 2020-03-27 | 施瓦哲工程实验有限公司 | Time domain line protection for power transmission systems |
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