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CN114417560A - Bus residual voltage detection method, motor voltage loss protection method, storage device and terminal - Google Patents

Bus residual voltage detection method, motor voltage loss protection method, storage device and terminal Download PDF

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CN114417560A
CN114417560A CN202111565000.2A CN202111565000A CN114417560A CN 114417560 A CN114417560 A CN 114417560A CN 202111565000 A CN202111565000 A CN 202111565000A CN 114417560 A CN114417560 A CN 114417560A
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voltage
bus
rotor
stator
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姬玉泽
陈文刚
宰洪涛
王新瑞
张轲
原亚飞
朱剑飞
刘贺龙
张玉娟
陈磊
姚泽龙
杨世宁
许泳涛
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Jincheng Power Supply Co of State Grid Shanxi Electric Power Co Ltd
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Abstract

The invention provides a bus residual voltage detection method, a motor voltage loss protection method, a storage device and a terminal, wherein the bus residual voltage detection method comprises the following steps: constructing a mathematical model of the counter electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus; analyzing the change rule of the phase angle in the bus voltage based on the mathematical model to obtain a relational expression between the differential quantity of the bus voltage space phase angle to time and the rotor angular speed; establishing a relational expression between the rotating speed of the motor and the angular speed of a rotor of the motor; analyzing the rotating speed and the rotor speed of the motor to obtain a relational expression between a rotating speed detection setting value and the rotating speed of the motor during normal operation; comparing the rotor rotating speed of the motor acquired in real time with a rotating speed detection setting value, and judging whether the bus voltage is the arrival of the back electromotive force of the motor; the method has the advantages that the method can achieve the beneficial effect of protecting the motor from voltage loss according to the characteristic quantity change of the bus residual voltage, and is suitable for the field of bus residual voltage detection.

Description

Bus residual voltage detection method, motor voltage loss protection method, storage device and terminal
Technical Field
The invention relates to the technical field of bus residual voltage detection, in particular to a bus residual voltage detection method, a motor voltage loss protection method, storage equipment and a terminal.
Background
In industrial production, when a large-capacity high-voltage motor suddenly encounters a power failure, a residual voltage (hereinafter, referred to as a residual voltage) temporarily exists on a bus side of the motor due to the generation of a back electromotive force, and the residual voltage can generally reach a high value.
According to different industrial production requirements, a standby automatic input power supply is configured for part of motors, and bus residual voltage generated by back electromotive force after the motors are stopped is mainly utilized for grid-connected detection, so that the power supply of the motors is quickly switched after power failure, and the motor is prevented from being stopped in the production process; however, for a motor which does not need to be switched over, in the shutdown operation process after power failure, because the bus side still has residual voltage, the situation that voltage is sent back to the power supply system side occurs, when the voltage value of the residual voltage reaches a larger value, potential risks can be generated on the user side, for example, bus residual voltage generated by counter electromotive force of the motor in a coal mine can cause gas coal dust explosion or cause electric shock and death of human bodies; when the voltage on the bus side is transmitted to the power supply system through the transformer, the failure of the automatic backup automatic switching device of the system can be influenced, and the protection misoperation of the transformer can be caused in serious cases, so that a large-area power failure accident is caused.
The motor is usually provided with the voltage loss protection, and the voltage loss protection can ensure that the motor is not started by itself when the power supply voltage is lower than the requirement of a restart voltage value, so that the damage to the motor caused by forced restart is avoided.
When the motor is in power failure, when the voltage value of the bus residual voltage generated by the counter electromotive force is low, the voltage failure protection can be detected and cut off, so that the influence of the counter electromotive force on a user and a system is eliminated; but when the voltage value of the bus residual voltage is higher, such as: when the voltage value of the residual voltage of the bus is larger than the setting range of the voltage loss protection, the voltage loss protection cannot detect and cut back electromotive force, so that the traditional voltage loss protection cannot accurately detect and cut back electromotive force of the motor.
In summary, the method for protecting the voltage loss of the motor based on the bus residual voltage detection is important for researching the bus residual voltage generated by the counter electromotive voltage of the motor so as to achieve the purpose of detecting the counter electromotive voltage, further improving the traditional voltage loss protection, and increasing the function of cutting off the counter electromotive voltage so as to protect the safe production of users and the safe operation of a power supply system.
Disclosure of Invention
Aiming at the defects in the related technology, the technical problem to be solved by the invention is as follows: the bus residual voltage detection method, the motor residual voltage protection method, the storage device and the terminal are provided for performing mathematical modeling analysis on the bus residual voltage and achieving motor residual voltage protection and eliminating back electromotive force after the motor is powered off according to the change of the characteristic quantity of the bus residual voltage.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the method for detecting the residual voltage of the motor bus is characterized by comprising the following steps: the method comprises the following steps:
s10, constructing a mathematical model of the counter electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus;
s20, analyzing the change rule of the phase angle in the bus voltage based on the mathematical model of the back electromotive force of the motor and the mathematical model of the initial value of the residual voltage of the bus, obtaining the relational expression between the differential quantity of the space phase angle of the bus voltage to time and the angular speed of the rotor, and the relational expression is as follows:
Figure BDA0003421763220000021
wherein:
Figure BDA0003421763220000022
is the differential quantity of the space phase angle of the bus voltage to the time, omegarIs the rotor angular velocity of the motor;
s30, establishing a relational expression between the rotating speed of the motor and the angular speed of the rotor of the motor, wherein the relational expression is as follows:
Figure BDA0003421763220000023
wherein: n isrAcquiring the rotor speed of the motor in real time, wherein kr is a conversion coefficient;
s40, analyzing the rotating speed and the rotor speed of the motor to obtain a relational expression between the rotating speed detection setting value and the rotating speed of the motor in normal operation, wherein the relational expression is as follows:
nset＝ns-. DELTA.n formula (3)
Wherein: n issetFor rotational speed detection of the setting value, nsThe motor speed is the rotating speed of the motor when the motor normally operates, and Delta n is an empirical error quantity;
s50, mixing nrAnd nsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the back electromotive force of the motor, it is determined that the bus voltage reaches the back electromotive force of the motor.
Preferably, in step S10, constructing a mathematical model of the back electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus, including:
s101, establishing a motor stator flux linkage equation, a rotor winding flux linkage equation and a stator current mathematical model:
the motor stator flux linkage equation is as follows:
Figure BDA0003421763220000024
in the formula (10), the coefficient Ks1、Ks2、Ks3、Ts'、TrThe expression of' is:
Figure BDA0003421763220000031
Ts'＝(Ls-Lm 2/Lr)/Rsformula (10-2)
Tr'＝(Lr-Lm 2/Ls)/RrFormula (10-3)
The flux linkage equation for the rotor winding is:
Figure BDA0003421763220000032
in the formula (11), the coefficient Kr1、Kr2、Kr3The expression of (a) is:
Figure BDA0003421763220000033
the mathematical model of the stator current is:
Figure BDA0003421763220000034
wherein:
Figure BDA0003421763220000041
is the bus voltage vector, ω, of the motorSFor the frequency of the network, MmMutual inductance for the stator windings and rotor windings of the motor; rrIs rotor resistance, RsIs stator resistance, ωrIs the rotor angular velocity of the motor;
LSis a stator inductance, LmFor exciting inductance, LrIs a rotor inductance;
ψs0、ψr0the initial values of the flux linkage of the stator and rotor loops are the flux linkage of the stator and rotor windings when the motor operates in a steady state;
s102, solving the stator flux linkage at the power-off moment of the motor according to the current zero-crossing time calculated by the stator current equation:
Figure BDA0003421763220000042
wherein: the solution equations for parameters s1, s2, and s3 are:
Figure BDA0003421763220000043
Tr＝Lr/Rr
s103, according to a flux linkage equation and a voltage equation at the power failure moment of the motor, an initial value of the voltage is obtained and expressed in a space vector coordinate as follows:
Figure BDA0003421763220000044
the formula (15) is a mathematical model of the initial value of the residual voltage of the bus.
Preferably, in S101, establishing a stator flux linkage equation of the motor, a flux linkage equation of the rotor winding, and a stator current mathematical model specifically includes:
s1011, establishing a vector expression of the initial voltage in the space when the motor normally operates as follows:
Figure BDA0003421763220000045
when the motor operates stably, the relationship between the stator flux linkage and the bus voltage is as follows:
Figure BDA0003421763220000046
s1012, constructing a flux linkage equation of a rotor and a flux linkage equation of a stator of the motor under the dq rotation coordinate system:
the flux linkage equation of the rotor is as follows:
Figure BDA0003421763220000051
the flux linkage equation of the stator is as follows:
Figure BDA0003421763220000052
wherein: psidr、ψqrComponents of the stator flux linkage in the d-and q-axes, ψds、ψqsThe components of the rotor flux linkage on the d-axis and the q-axis respectively; sigma is a magnetic leakage coefficient, and the value is as follows: σ ═ 1-Lm 2/LrLs；ids、iqsThe components of the stator current on the d-axis and the q-axis, respectively; u. ofds、uqsThe components of the stator voltage on the d axis and the q axis respectively;
s1013, establishing a voltage equation of the stator and a voltage equation of the rotor as follows:
Figure BDA0003421763220000053
Figure BDA0003421763220000054
wherein: u. ofdr、uqrThe components of the rotor voltage on the d axis and the q axis respectively; i.e. idrAnd iqrThe components of the rotor current on the d-axis and the q-axis;
s1014, according to the flux linkage equation of the rotor, the flux linkage equation of the stator, the voltage equation of the stator and the voltage equation of the rotor, obtaining that when the motor normally operates, the steady-state flux linkage equation of the rotor is as follows:
Figure BDA0003421763220000055
s1015, when the voltage begins to drop, the motor stator flux linkage equation is as follows:
Figure BDA0003421763220000061
s1016, establishing a flux linkage equation of the rotor winding when the voltage drops:
Figure BDA0003421763220000062
s1017, when the voltage drops, the calculation expression of the stator current is as follows:
Figure BDA0003421763220000063
s1018, recording the stator zero-crossing time as:t＝tm(ii) a And establishing an equation:
Figure BDA0003421763220000064
solving equation (13) yields: the stator flux linkage at the moment of power failure of the motor is as follows:
Figure BDA0003421763220000065
s1019, according to the flux linkage equation and the voltage equation, the initial value of the voltage is obtained and expressed in the space vector coordinate as:
Figure BDA0003421763220000066
preferably, according to equation (15), the expression of the amplitude and the phase angle of the initial value of the bus residual voltage is:
Figure BDA0003421763220000067
Figure BDA0003421763220000068
according to the equation (15-2), the change law of the phase angle in space is as follows:
Figure BDA0003421763220000069
wherein: t isr＝Lr/Rr(ii) a In the above expression, us(t) is the initial value of the bus residual voltage; u shapes(t) is the amplitude of the initial value of the residual voltage of the bus, thetaus(t) is the phase angle, omega, of the initial value of the residual voltage of the busrIs the rotor angular velocity, psi, of the motors0Is the initial value of the stator winding flux linkage, and t is time.
Correspondingly, the motor voltage loss protection method based on the bus residual voltage detection comprises the following steps:
a10, monitoring the bus voltage and extracting the bus voltage angle;
a20, calculating the differential quantity of the bus voltage space phase angle to time
Figure BDA0003421763220000071
A30, calculating the rotation speed of the motor
Figure BDA0003421763220000072
A40, judging whether the back electromotive force arrives, if so, executing the step A50, otherwise, executing the step A60;
a50, sending an action signal according to the voltage loss protection setting value and the time limit value;
a60, locking.
Preferably, the determining whether the back electromotive force arrives is specifically:
real-time collected rotor speed n of motorrDetecting setting value n with rotating speedsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the counter electromotive force of the motor, the bus voltage is judged to reach the counter electromotive force of the motor;
n isset＝ns-△n；
N issThe rotation speed of the motor when the motor normally operates, and Δ n is an empirical error.
Preferably, the step S50 includes: sending an action signal according to the voltage loss protection setting value and the time limit value, and specifically comprising the following steps:
s501, judging whether | U is satisfiedres|≤UopIf satisfied, the time limit value t is outputop；
The U isopThe voltage loss protection setting value based on bus residual voltage detection has the expression:
Figure BDA0003421763220000073
wherein: u shapeN.minVoltage allowed minimum value, k, for normal operation of the motorrIs the return coefficient of the relay; k is a radical ofrelIs a reliability factor;
s502, obtaining a setting value U of the traditional voltage loss protectionop.1And a time limit value top.1；
S503, judging whether the time limit value t is metop.1Or time limit value topIf one of the signals is satisfied, an action signal is sent out.
Preferably, in the step S50, the time limit value top.1The sum time limit value is topThe relationship between them is:
top＝top.1+ DELTAt type (17)
Wherein: Δ t is the time limit margin.
Accordingly, a storage device having stored therein a plurality of instructions adapted to be loaded by a processor and to execute the motor bus residual voltage detection method as described above.
Accordingly, a terminal, characterized by: the method comprises the following steps:
a processor adapted to implement instructions; and
the storage device is suitable for storing a plurality of instructions, and the instructions are suitable for being loaded by the processor and executing the motor bus residual voltage detection method.
The invention has the beneficial technical effects that:
1. according to the method for detecting the residual voltage of the motor bus, the mathematical model of the counter electromotive force of the motor and the mathematical model of the initial value of the residual voltage of the bus are constructed, the initial value phase angle differential quantity of the counter electromotive force of the motor is used as a parameter for identifying the counter electromotive force, the counter electromotive force is effectively subjected to information detection and identification, and the identification sensitivity of the counter electromotive force is improved.
2. The invention discloses a motor voltage loss protection method based on bus residual voltage detection, and provides a voltage loss protection method based on bus residual voltage initial value phase angle differential quantity detection, so that counter electromotive force is effectively removed, and harm to users and a power grid is reduced.
3. According to the invention, the back electromotive force identification detection is added on the basis of the traditional voltage loss protection, so that the reliability and selectivity of the voltage loss protection are improved, and the reliable operation of the motor is ensured.
Drawings
FIG. 1 is a schematic flow chart of a method for detecting residual voltage of a bus of a motor according to the present invention;
FIG. 2 is a schematic diagram of an equivalent circuit model of the motor of the present invention;
FIG. 3 is a schematic diagram showing the variation law of the reaction potential in the present invention;
FIG. 4 is a schematic flow chart of a motor voltage loss protection method based on bus residual voltage detection according to the present invention;
fig. 5 is a schematic diagram of an action module of the motor voltage loss protection method in the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments, but not all embodiments, of the present invention; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Next, the present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially according to the general scale for convenience of illustration when describing the embodiments of the present invention, and the drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
An embodiment of the present invention is described in detail below with reference to the accompanying drawings.
Example one
As shown in fig. 1, the method for detecting the residual voltage of the bus of the motor comprises the following steps:
s10, constructing a mathematical model of the counter electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus;
s20, analyzing the change rule of the phase angle in the bus voltage based on the mathematical model of the back electromotive force of the motor and the mathematical model of the initial value of the residual voltage of the bus, obtaining the relational expression between the differential quantity of the space phase angle of the bus voltage to time and the angular speed of the rotor, and the relational expression is as follows:
Figure BDA0003421763220000091
wherein:
Figure BDA0003421763220000092
is the differential quantity of the space phase angle of the bus voltage to the time, omegarIs the rotor angular velocity of the motor;
s30, establishing a relational expression between the rotating speed of the motor and the angular speed of the rotor of the motor, wherein the relational expression is as follows:
Figure BDA0003421763220000093
wherein: n isrAcquiring the rotor speed of the motor in real time, wherein kr is a conversion coefficient;
s40, analyzing the rotating speed and the rotor speed of the motor to obtain a relational expression between the rotating speed detection setting value and the rotating speed of the motor in normal operation, wherein the relational expression is as follows:
nset＝ns-. DELTA.n formula (3)
Wherein: n issThe motor speed is the rotating speed of the motor when the motor normally operates, and Delta n is an empirical error quantity;
s50, mixing nrAnd nsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the back electromotive force of the motor, it is determined that the bus voltage reaches the back electromotive force of the motor.
According to the method for detecting the residual voltage of the motor bus, the mathematical model of the counter electromotive force of the motor and the mathematical model of the initial value of the residual voltage of the bus are constructed, the initial value phase angle differential quantity of the counter electromotive force of the motor is used as a parameter for identifying the counter electromotive force, the counter electromotive force is effectively subjected to information detection and identification, and the identification sensitivity of the counter electromotive force is improved.
Example two
FIG. 2 is a schematic diagram of an equivalent circuit model of the motor of the present invention; in FIG. 2, u is the motor bus voltage, ω is the power frequency of the grid, S is the motor slip, RrIs rotor resistance, RsIs stator resistance, RmIs an excitation resistor; l isSIs a stator inductance, LmFor exciting inductance, LrIs a rotor inductance; omegarIs the rotor angular velocity of the motor; normal operation of the motor, omegar＝(1-s)ωs；
In this application, ωsThe stator voltage frequency of the motor in normal operation is equal to the grid frequency and omega.
As shown in fig. 3, on the basis of the first embodiment, in step S10, the mathematical model of the back electromotive force of the motor and the mathematical model of the initial value of the bus residual voltage are constructed, including:
s101, establishing a motor stator flux linkage equation, a rotor winding flux linkage equation and a stator current mathematical model: the method specifically comprises the following steps:
s1011, establishing a vector expression of the initial voltage in the space when the motor normally operates as follows:
Figure BDA0003421763220000101
when the motor operates stably, the relationship between the stator flux linkage and the bus voltage is as follows:
Figure BDA0003421763220000102
s1012, constructing a flux linkage equation of a rotor and a flux linkage equation of a stator of the motor under the dq rotation coordinate system:
the flux linkage equation of the rotor is as follows:
Figure BDA0003421763220000103
the flux linkage equation of the stator is as follows:
Figure BDA0003421763220000104
wherein: psidr、ψqrComponents of the stator flux linkage in the d-and q-axes, ψds、ψqsThe components of the rotor flux linkage on the d-axis and the q-axis respectively; sigma is a magnetic leakage coefficient, and the value is as follows: σ ═ 1-Lm 2/LrLs；ids、iqsThe components of the stator current on the d-axis and the q-axis, respectively; u. ofds、uqsThe components of the stator voltage on the d axis and the q axis respectively;
s1013, establishing a voltage equation of the stator and a voltage equation of the rotor as follows:
Figure BDA0003421763220000111
Figure BDA0003421763220000112
wherein: u. ofdr、uqrThe components of the rotor voltage on the d axis and the q axis respectively; i.e. idrAnd iqrThe components of the rotor current on the d-axis and the q-axis;
s1014, according to the flux linkage equation of the rotor, the flux linkage equation of the stator, the voltage equation of the stator and the voltage equation of the rotor, obtaining that when the motor normally operates, the steady-state flux linkage equation of the rotor is as follows:
Figure BDA0003421763220000113
generally, when a motor is normally operated, when a sudden power failure occurs, the stator current suddenly drops to zero, but the magnetic field generated by the stator current does not instantaneously drop to zero, and since the magnetic flux of the stator winding cannot suddenly change, a direct current component is induced in the stator winding and is attenuated and changed in the stator winding, so that the attenuation time constant of the direct current component is related to the stator winding parameters.
Because of the disappearance of the stator current, the space flux linkage in the motor is conserved, instantaneous induction current can be generated in the rotor winding to counteract the magnetic flux change caused by the sudden disappearance of the stator current so as to maintain the magnetic flux not to be suddenly changed, and the magnetic field generated by the rotor winding current is relatively static with the rotor, and due to the inertial motion of the rotor, the magnetic field cuts the stator winding to omegarIs the rotor speed, this current decays with the rotor winding time constant, being a slowly varying current component.
Therefore, when the external power supply is suddenly removed, the flux linkage of the motor is composed of three parts:
one part is a magnetic linkage generated by a direct current component induced by the change of the magnetic field of the stator winding;
the second part is a flux linkage induced by the conservation of flux linkage in the stator winding; the magnetic flux linkage generated by cutting the stator by the magnetic field generated by the induction current of the rotor winding;
the third part is that the initial magnetic flux in the stator winding can not change suddenly and is still in a turn stator winding;
therefore, according to the above theory, it follows:
s1015, when the voltage begins to drop, the motor stator flux linkage equation is as follows:
Figure BDA0003421763220000121
in the formula (10), the coefficient Ks1、Ks2、Ks3、Ts'、TrThe expression of' is:
Figure BDA0003421763220000122
Ts'＝(Ls-Lm 2/Lr)/Rsformula (10-2)
Tr'＝(Lr-Lm 2/Ls)/RrFormula (10-3)
S1016, establishing a flux linkage equation of the rotor winding when the voltage drops:
Figure BDA0003421763220000123
in the formula (11), the coefficient Kr1、Kr2、Kr3The expression of (a) is:
Figure BDA0003421763220000124
s1017, when the voltage drops, the calculation expression of the stator current is as follows:
Figure BDA0003421763220000131
wherein: mmMutual inductance for the stator windings and rotor windings of the motor; psis0、ψr0The initial values of the flux linkage of the stator and rotor loops are the flux linkage of the stator and rotor windings when the motor operates in a steady state;
in this embodiment, the initial value of the back electromotive force is calculated using the current in equation (12):
when the stator current is reduced to zero, the counter electromotive force takes an initial value, therefore, the zero-crossing time of the stator current is solved through an expression of the stator current, the initial value of the flux linkage is solved through the zero-crossing time, and the initial value of the voltage, namely the initial value of the counter electromotive force, is solved according to a flux linkage equation.
S1018, recording the stator zero-crossing time as: t is tm(ii) a And establishing an equation:
Figure BDA0003421763220000132
solving equation (13) yields: the stator flux linkage at the moment of power failure of the motor is as follows:
Figure BDA0003421763220000133
wherein: the solution equations for parameters s1, s2, and s3 are:
Figure BDA0003421763220000134
Tr＝Lr/Rr
s1019, according to the flux linkage equation and the voltage equation, the initial value of the voltage is obtained and expressed in the space vector coordinate as:
Figure BDA0003421763220000135
the formula (15) is a mathematical model of the initial value of the residual voltage of the bus.
In this embodiment, a mathematical model of the initial value of the residual voltage of the bus is established by deriving the initial value of the back electromotive force, and the model can be divided into two parts for analysis.
According to the formula (15), the expression of the amplitude and the phase angle of the initial value of the bus residual voltage is as follows:
Figure BDA0003421763220000136
Figure BDA0003421763220000141
wherein: t isr＝Lr/Rr(ii) a In the above expression, us(t) is the initial value of the bus residual voltage; u shapes(t) is the amplitude of the initial value of the residual voltage of the bus, thetaus(t) is the phase angle of the initial value of the residual voltage of the bus bar, psis0Is the initial value of the stator winding flux linkage, and t is time.
As shown in fig. 3, the law of change of the reaction potential is: with angular frequency ω of the rotorrThe amplitude of the back electromotive force is gradually reduced; at the same time, with the time constant T of the rotorrDecaying exponentially; the change rule of the phase angle is gradually reduced along with the reduction of the angular frequency of the rotor.
Therefore, according to the equation (15-2), the change law of the phase angle in space is:
Figure BDA0003421763220000142
then, the relational expression between the differential quantity of the bus voltage space phase angle to time and the rotor angular speed is as follows:
Figure BDA0003421763220000143
wherein:
Figure BDA0003421763220000144
is the differential quantity of the space phase angle of the bus voltage to the time, omegarIs the rotor angular velocity of the motor;
as can be seen from equation (1), the differential amount of the phase angle of the counter electromotive force is the rotor angular velocity after the motor is de-energized, and therefore the counter electromotive force can be identified by detecting the change in this characteristic amount.
By detecting the angular velocity of the rotor, a conversion is made into a rotational speed, since:
Figure BDA0003421763220000145
ω＝2πf
wherein: n is the rotating speed, f is the frequency, and p is the magnetic pole pair number of the motor;
thus, it is possible to obtain:
Figure BDA0003421763220000146
according to the theory, the relational expression between the rotating speed of the motor and the angular speed of the rotor of the motor is established, and is as follows:
Figure BDA0003421763220000147
in general, when the motor is operating stably, ωrThe rotation speed of the motor is kept constant as follows: n iss＝(1-s)nN(ii) a Wherein n isNThe rotation speed of the magnetic field generated by the stator of the motor under the rated frequency is s is slip ratio, which is usually between 0.02-0.05, so the rotation speed of the motor is slightly lower than the rotation speed of the magnetic field, which is usually (0.95-0.97) nNIn the meantime.
When the outside of the motor is suddenly de-energized, the rotating speed of the motor begins to be reduced, and at the initial moment, due to the inertia of the high-speed motion of the rotor, the speed of the rotor is still very high, so that very large back electromotive force is generated and sent back to the bus, and the bus has very high residual voltage; and reflecting the change of the back electromotive force according to the phase angle of the detected bus residual voltage and the change of the differential quantity of the phase angle at the initial moment.
Usually, the rotational speed of the motor is kept constant at the initial time by inertia, and therefore, at the initial time, the differential detection amount of the phase angle is the initial rotational speed of the rotor, that is, (0.95 to 0.97) nNHowever, considering the influence of the acquisition error and the resistance consumption of the motor, n is appropriately setsAdjusting, and increasing an empirical error quantity delta n according to operation experience, so that a concept of a rotating speed detection setting value is introduced, namely: the differential of the phase angle is set to ns-△n；
The relational expression between the speed detection setting value and the rotating speed of the motor is as follows:
nset＝ns-. DELTA.n formula (3)
Wherein: n issetDetecting a setting value for the rotating speed, wherein delta n is an empirical error quantity;
thus, the identification of the reaction potential is represented as: real-time acquisition of rotor speed n of motorrAnd n isrAnd nsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the back electromotive force of the motor, it is determined that the bus voltage reaches the back electromotive force of the motor.
Namely: when the motor is operating normally, nr＝nset(ii) a When the motor is de-energized, the rotational speed of the motor begins to decrease, and therefore nr≤nset。
In addition, the invention also provides a motor voltage loss protection method based on bus residual voltage detection.
The motor voltage loss protection has the main functions of realizing self-starting or automatic power-off of the motor when voltage is reduced due to short-time voltage disappearance or short circuit in a power grid, and protecting load and production process flow from loss; the voltage loss protection is usually realized by a low voltage protection acting on tripping, so the setting value of the low voltage is different according to the operation requirement of the motor.
After the motor loses power, if the motor allows self-starting, because of the generation of counter electromotive force, the residual voltage of a bus is large, the rapid switching of a power supply can be rapidly realized to realize the self-starting, but when the motor does not allow the self-starting, the existence of the counter electromotive force can generate potential harm and particularly can influence the stable operation of a power grid, once the counter electromotive force is high, the generated bus residual voltage is large, and when the counter electromotive force does not reach the setting value of voltage loss protection, the bus voltage is sent back to a high-voltage side through a transformer of a transformer substation, the action of a power grid automatic device can be influenced, even protection misoperation is caused, and power failure accidents in the power grid are triggered.
As shown in fig. 4, the method for protecting the voltage loss of the motor based on the bus residual voltage detection includes the following steps:
a10, monitoring the bus voltage and extracting the bus voltage angle;
a20, calculating the differential quantity of the bus voltage space phase angle to time
Figure BDA0003421763220000151
A30, calculating the rotation speed of the motor
Figure BDA0003421763220000161
A40, judging whether the back electromotive force arrives, if so, executing the step A50, otherwise, executing the step A60;
a50, sending an action signal according to the voltage loss protection setting value and the time limit value;
a60, locking.
The invention discloses a motor voltage loss protection method based on bus residual voltage detection, and provides a voltage loss protection method based on bus residual voltage initial value phase angle differential quantity detection, so that counter electromotive force is effectively removed, and harm to users and a power grid is reduced.
Specifically, the determining whether the back electromotive force arrives includes:
real-time collected rotor speed n of motorrDetecting setting value n with rotating speedsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the counter electromotive force of the motor, the bus voltage is judged to reach the counter electromotive force of the motor;
n isset＝ns-△n；
N issThe rotation speed of the motor when the motor normally operates, and Δ n is an empirical error.
Further, the step S50 includes: sending an action signal according to the voltage loss protection setting value and the time limit value, and specifically comprising the following steps:
s501, judging whether | U is satisfiedres|≤UopIf satisfied, the time limit value t is outputop；
The U isopThe voltage loss protection setting value based on bus residual voltage detection has the expression:
Figure BDA0003421763220000162
wherein: u shapeN.minVoltage allowed minimum value, k, for normal operation of the motorrIs the return coefficient of the relay; k is a radical ofrelIs a reliability factor;
s502, obtaining a setting value U of the traditional voltage loss protectionop.1And a time limit value top.1；
S503, judging whether the time limit value t is metop.1Or time limit value topIf one of the signals is satisfied, an action signal is sent out. Further, in the step S50, the time limit value top.1The sum time limit value is topThe relationship between them is:
top＝top.1+ DELTAt type (17)
Wherein: Δ t is the time limit margin.
In the embodiment, a logic criterion of back electromotive force is added on the basis of the traditional motor voltage loss protection, so that the reliability of detecting and cutting off the motor voltage loss by only depending on the single criterion of voltage is improved.
During setting of traditional voltage loss protection, according to the condition setting of cutting of a self-starting motor which is not allowed, the voltage is generally:
Uop＝0.6～0.7UN；
the protection action is realized for 0.5s to avoid the false action caused by quick-break protection and the broken line of the voltage loop.
When the motor normally operates, the allowable range of the voltage is generally (0.95-1.10) UN(ii) a Therefore, after the counter electromotive force is detected, a signal is sent to the low-voltage judging module, the low-voltage judging module judges, and the setting value is as follows:
Figure BDA0003421763220000171
wherein: u shapeN.minThe voltage allowed minimum value for normal operation of the motor is generally 0.95UN；
krThe return coefficient of the relay is generally 0.85; k is a radical ofrelThe reliability coefficient is generally 1.2; therefore, in this embodiment, Uop≈0.8UN
The action time limit should be matched with the voltage loss protection:
top＝top.1+△t
wherein: t is top.1For realizing the operation of the voltage loss protection, the time limit margin is delta t, and is generally 0.5s, so the operation time limit is 1 s.
As shown in fig. 5, the implementation process of the action module is as follows:
firstly, the voltage U of the motor bus is measuredresCollecting angle theta, wherein the collecting part comprises a voltage amplitude part | UresI and phase angle θ (t);
secondly, the differential calculation is carried out on the phase angle
Figure BDA0003421763220000172
Calculating corresponding rotating speed n through the coefficient krrComparing with the setting value, if nr≤nsetThe differential quantity of the phase angle detects that the bus voltage is the arrival of the back electromotive force of the motor, and the amplitude | U of the voltageres|≤UopWhen both the two conditions are satisfied, the protection acts;
in addition, in the embodiment, the voltage loss protection based on the phase angle differential detection is matched with the traditional voltage loss protection when the voltage amplitude | Ures|≤Uop.1When the voltage is lost, the voltage is protected; the two types of protection are matched, the time limit of the voltage loss protection is short, the threshold value is low, therefore, the traditional voltage loss protection is preferentially judged and operated, the initial value of the back electromotive force of a general large-capacity motor is high, the phase angle differential quantity can be detected under the condition that the voltage loss protection cannot be cut off, the operation can be cut off under the condition that the voltage loss protection cannot be judged and cut off, the defect of the traditional voltage loss protection is overcome, and meanwhile, the triggering locking of the non-back electromotive force signal is realized based on the detection of the phase angle differential quantity.
In conclusion, the back electromotive force identification detection is added on the basis of the traditional voltage loss protection, so that the reliability and the selectivity of the voltage loss protection are improved, and the reliable operation of the motor is guaranteed.
The invention also provides a storage device, wherein a plurality of instructions are stored, and the instructions are suitable for being loaded by a processor and executing the motor bus residual voltage detection method.
The present invention also provides a terminal, which may include:
a processor adapted to implement instructions; and
the storage device is suitable for storing a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the motor bus residual voltage detection method according to the flower girl.
The storage device may be a computer-readable storage medium, and may include: ROM, RAM, magnetic or optical disks, and the like.
The terminal can be any device capable of realizing the method for detecting the residual voltage of the motor bus, and the device can be various terminal equipment, such as: desktop computers, portable computers, etc., may be implemented in software and/or hardware.
In the description of the present invention, it should be understood that the terms "mounted," "connected," "fixed," and the like are used in a broad sense, and for example, may be fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The algorithms and displays presented herein are not inherently related to any particular computer, virtual machine, or other apparatus. Various general purpose systems may also be used with the teachings herein. The required structure for constructing such a device will be apparent from the description above. In addition, the present invention is not directed to any particular programming language. It is appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any descriptions of specific languages are provided above to disclose the best mode of the invention.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The method for detecting the residual voltage of the motor bus is characterized by comprising the following steps: the method comprises the following steps:
s10, constructing a mathematical model of the counter electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus;
s20, analyzing the change rule of the phase angle in the bus voltage based on the mathematical model of the back electromotive force of the motor and the mathematical model of the initial value of the residual voltage of the bus, obtaining the relational expression between the differential quantity of the space phase angle of the bus voltage to time and the angular speed of the rotor, and the relational expression is as follows:
Figure FDA0003421763210000011
wherein:
Figure FDA0003421763210000012
is the differential quantity of the space phase angle of the bus voltage to the time, omegarIs the rotor angular velocity of the motor;
s30, establishing a relational expression between the rotating speed of the motor and the angular speed of the rotor of the motor, wherein the relational expression is as follows:
Figure FDA0003421763210000013
wherein: n isrAcquiring the rotor speed of the motor in real time, wherein kr is a conversion coefficient;
s40, analyzing the rotating speed and the rotor speed of the motor to obtain a relational expression between the rotating speed detection setting value and the rotating speed of the motor in normal operation, wherein the relational expression is as follows:
nset＝ns-. DELTA.n formula (3)
Wherein: n issetFor rotational speed detection of the setting value, nsThe motor speed is the rotating speed of the motor when the motor normally operates, and Delta n is an empirical error quantity;
s50, mixing nrAnd nsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the back electromotive force of the motor, it is determined that the bus voltage reaches the back electromotive force of the motor.
2. The method of claim 1, wherein: in step S10, a mathematical model of the back electromotive force of the motor and a mathematical model of the initial value of the residual voltage of the bus are constructed, including:
s101, establishing a motor stator flux linkage equation, a rotor winding flux linkage equation and a stator current mathematical model:
the motor stator flux linkage equation is as follows:
Figure FDA0003421763210000014
in the formula (10), the coefficient Ks1、Ks2、Ks3、Ts'、TrThe expression of' is:
Figure FDA0003421763210000021
Ts'＝(Ls-Lm 2/Lr)/Rsformula (10-2)
Tr'＝(Lr-Lm 2/Ls)/RrFormula (10-3)
The flux linkage equation for the rotor winding is:
Figure FDA0003421763210000022
in the formula (11), the coefficient Kr1、Kr2、Kr3The expression of (a) is:
Figure FDA0003421763210000023
the mathematical model of the stator current is:
Figure FDA0003421763210000024
wherein:
Figure FDA0003421763210000031
is the bus voltage vector, ω, of the motorSFor the frequency of the network, MmMutual inductance for the stator windings and rotor windings of the motor; rrIs rotor resistance, RsIs stator resistance, ωrIs the rotor angular velocity of the motor;
LSis a stator inductance, LmFor exciting inductance, LrIs a rotor inductance;
ψs0、ψr0the initial values of the flux linkage of the stator and rotor loops are the flux linkage of the stator and rotor windings when the motor operates in a steady state;
s102, solving the stator flux linkage at the power-off moment of the motor according to the current zero-crossing time calculated by the stator current equation:
Figure FDA0003421763210000032
wherein: the solution equations for parameters s1, s2, and s3 are:
Figure FDA0003421763210000033
Tr＝Lr/Rr
s103, according to a flux linkage equation and a voltage equation at the power failure moment of the motor, an initial value of the voltage is obtained and expressed in a space vector coordinate as follows:
Figure FDA0003421763210000034
the formula (15) is a mathematical model of the initial value of the residual voltage of the bus.
3. The method of claim 2, wherein: s101, establishing a motor stator flux linkage equation, a rotor winding flux linkage equation and a stator current mathematical model, and specifically comprising the following steps:
s1011, establishing a vector expression of the initial voltage in the space when the motor normally operates as follows:
Figure FDA0003421763210000035
when the motor operates stably, the relationship between the stator flux linkage and the bus voltage is as follows:
Figure FDA0003421763210000036
s1012, constructing a flux linkage equation of a rotor and a flux linkage equation of a stator of the motor under the dq rotation coordinate system:
the flux linkage equation of the rotor is as follows:
Figure FDA0003421763210000041
the flux linkage equation of the stator is as follows:
Figure FDA0003421763210000042
wherein: psidr、ψqrComponents of the stator flux linkage in the d-and q-axes, ψds、ψqsThe components of the rotor flux linkage on the d-axis and the q-axis respectively; sigma is a magnetic leakage coefficient, and the value is as follows: σ ═ 1-Lm 2/LrLs；ids、iqsThe components of the stator current on the d-axis and the q-axis, respectively; u. ofds、uqsThe components of the stator voltage on the d axis and the q axis respectively;
s1013, establishing a voltage equation of the stator and a voltage equation of the rotor as follows:
Figure FDA0003421763210000043
Figure FDA0003421763210000044
wherein: u. ofdr、uqrThe components of the rotor voltage on the d axis and the q axis respectively; i.e. idrAnd iqrThe components of the rotor current on the d-axis and the q-axis;
s1014, according to the flux linkage equation of the rotor, the flux linkage equation of the stator, the voltage equation of the stator and the voltage equation of the rotor, obtaining that when the motor normally operates, the steady-state flux linkage equation of the rotor is as follows:
Figure FDA0003421763210000045
s1015, when the voltage begins to drop, the motor stator flux linkage equation is as follows:
Figure FDA0003421763210000051
s1016, establishing a flux linkage equation of the rotor winding when the voltage drops:
Figure FDA0003421763210000052
s1017, when the voltage drops, the calculation expression of the stator current is as follows:
Figure FDA0003421763210000053
s1018, recording the stator zero-crossing time as: t is tm(ii) a And establishing an equation:
Figure FDA0003421763210000054
solving equation (13) yields: the stator flux linkage at the moment of power failure of the motor is as follows:
Figure FDA0003421763210000055
s1019, according to the flux linkage equation and the voltage equation, the initial value of the voltage is obtained and expressed in the space vector coordinate as:
Figure FDA0003421763210000056
4. the method of claim 2, wherein: according to the formula (15), the expression of the amplitude and the phase angle of the initial value of the bus residual voltage is as follows:
Figure FDA0003421763210000057
Figure FDA0003421763210000058
according to the equation (15-2), the change law of the phase angle in space is as follows:
Figure FDA0003421763210000059
wherein: t isr＝Lr/Rr(ii) a In the above expression, us(t) is the initial value of the bus residual voltage; u shapes(t) is the amplitude of the initial value of the residual voltage of the bus, thetaus(t) is the phase angle, omega, of the initial value of the residual voltage of the busrIs the rotor angular velocity, psi, of the motors0Is the initial value of the stator winding flux linkage, and t is time.
5. A motor voltage loss protection method based on bus residual voltage detection is characterized in that: the method comprises the following steps:
a10, monitoring the bus voltage and extracting the bus voltage angle;
a20, calculating the differential quantity of the bus voltage space phase angle to time
Figure FDA0003421763210000061
A30, calculating the rotation speed of the motor
Figure FDA0003421763210000062
A40, judging whether the back electromotive force arrives, if so, executing the step A50, otherwise, executing the step A60;
a50, sending an action signal according to the voltage loss protection setting value and the time limit value;
a60, locking.
6. The method for protecting the voltage loss of the motor based on the bus residual voltage detection as claimed in claim 5, wherein: the judging whether the back electromotive force arrives specifically includes:
real-time collected rotor speed n of motorrDetecting setting value n with rotating speedsetMaking a comparison when nr≤nsetWhen the bus voltage reaches the counter electromotive force of the motor, the bus voltage is judged to reach the counter electromotive force of the motor;
n isset＝ns-△n；
N issThe rotation speed of the motor when the motor normally operates, and Δ n is an empirical error.
7. The method for protecting the voltage loss of the motor based on the bus residual voltage detection as claimed in claim 5, wherein: the step S50 includes: sending an action signal according to the voltage loss protection setting value and the time limit value, and specifically comprising the following steps:
s501, judging whether | U is satisfiedres|≤UopIf satisfied, the time limit value t is outputop；
The U isopThe voltage loss protection setting value based on bus residual voltage detection has the expression:
Figure FDA0003421763210000063
wherein: u shapeN.minVoltage allowed minimum value, k, for normal operation of the motorrIs the return coefficient of the relay; k is a radical ofrelIs a reliability factor;
s502, obtaining a setting value U of the traditional voltage loss protectionop.1And a time limit value top.1；
S503, judging whether the time limit value t is metop.1Or time limit value topIf one of the signals is satisfied, an action signal is sent out.
8. The method for protecting the voltage loss of the motor based on the bus residual voltage detection as claimed in claim 5, wherein: in the step S50, the time limit value top.1The sum time limit value is topThe relationship between them is:
top＝top.1+ DELTAt type (17)
Wherein: Δ t is the time limit margin.
9. A storage device having a plurality of instructions stored therein, characterized in that: the instructions are suitable for being loaded by a processor and executing the motor bus residual voltage detection method according to any one of claims 1 to 4.
10. A terminal, characterized in that: the method comprises the following steps:
a processor adapted to implement instructions; and
a storage device adapted to store a plurality of instructions adapted to be loaded by a processor and to perform the method of any of claims 1 to 4.
CN202111565000.2A 2021-12-20 2021-12-20 Bus residual voltage detection method, motor voltage loss protection method, storage device and terminal Pending CN114417560A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114876799A (en) * 2022-05-27 2022-08-09 沈阳工业大学 Method for estimating re-electrifying time after vacuum pump direct exhaust atmosphere speed reduction

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114876799A (en) * 2022-05-27 2022-08-09 沈阳工业大学 Method for estimating re-electrifying time after vacuum pump direct exhaust atmosphere speed reduction
CN114876799B (en) * 2022-05-27 2024-05-28 沈阳工业大学 Method for estimating time for re-powering up after direct exhaust air speed reduction of vacuum pump

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