Anti-interference electricity device and method based on magnetic switch

Abstract

The invention discloses an anti-interference electricity device and method based on a magnetic switch, and relates to the technical field of anti-interference electricity, according to the anti-interference electricity device and method based on the magnetic switch, the interference of instantaneous voltage fluctuation is reduced by adopting moving average filtering, the instantaneous change of a low-frequency component is extracted in combination with short-time Fourier transform (STFT), the identification of the voltage drop of a power grid is more accurate, and the anti-interference electricity device and method based on the magnetic switch are more reliable. The problem of misjudgment or missed judgment caused by short-time fluctuation in a traditional method is effectively avoided; according to the alternating current and direct current switching strategy, the current voltage phase is calculated, the optimal switching phase is matched, it is guaranteed that the alternating current and direct current voltage difference is minimum in the switching process, and therefore current impact is reduced, and contactor contact vibration caused by phase deviation is avoided; meanwhile, the direct current support voltage is dynamically adjusted by combining an exponential smoothing function, and the voltage change in the switching process is more stable; in a direct-current supporting mode, the stability of the contactor contact is enhanced by adopting a magnetic locking technology, and the contact is not mistakenly released due to fluctuation of electromagnetic attraction during interference electricity by monitoring the state quantity of the contact in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of anti - power - fluctuation, and particularly to an anti - power - fluctuation device and method based on a magnetic switch. Background Art

[0002] In industrial production and power systems, power - fluctuation phenomena widely exist. Power - fluctuation is caused by transmission line faults, large - load impacts, or remote power - grid disturbances. Although the duration is short, it can still cause equipment tripping, production interruption, and even equipment damage.

[0003] Traditional anti - power - fluctuation methods mainly start from the power - supply side and the load side, such as dynamic reactive - power compensation (SVG), dual - power - source switching, low - voltage ride - through for inverters, or contactor - holding modules, etc. Such methods are difficult to take into account different load characteristics. For equipment that relies on electromagnetic attraction, such as AC contactors, even if the power supply is quickly restored, they may be accidentally released due to fluctuations in electromagnetic attraction, resulting in unexpected power - off of the load.

[0004] To reduce such risks, common solutions use DC support modules to provide short - time DC to maintain the excitation of the contactor coil when the voltage drops. However, different contactors have different responses to DC support, and phase mismatch during the switching process may cause short - time current mutations, resulting in slight vibrations of the contacts. Such vibrations do not immediately cause equipment shutdown, but may affect the life of the contactor and, in high - sensitivity load scenarios, such as continuous production lines or data centers, may cause relay mis - triggering or abnormal control systems. Existing flexible - switching solutions calculate the optimal switching phase through fixed logic, reducing the impact, but in the face of different load characteristics, especially high - power contactors, there may still be slight vibrations, affecting system stability. Therefore, without increasing additional hardware costs, how to optimize the anti - power - fluctuation ability of contactors and prevent contact vibrations during the switching process has become an important optimization direction for anti - power - fluctuation technology. Summary of the Invention

[0005] In view of the above - mentioned existing problems, the present invention is proposed.

[0006] The present invention provides an anti - power - fluctuation device and method based on a magnetic switch to solve the problems that contactors may still be accidentally released after power - supply restoration, the DC support scheme has unstable responses under different loads, and phase mismatch during switching causes contact vibrations, affecting equipment life and system stability.

[0007] To solve the above - mentioned technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present invention provides an anti - power - fluctuation device based on a magnetic switch, which includes

[0009] a voltage - detection module, a switching - control module, a DC - support module, a magnetic - stability module, a state - monitoring module, and a power - supply - restoration module:

[0010] The voltage detection module is used to detect the change of grid voltage, judge whether power flicker occurs, and output a power flicker signal when the voltage is lower than the set threshold;

[0011] The switching control module receives the power flicker signal, calculates the optimal AC-DC switching phase, and outputs a phase control signal;

[0012] The DC support module receives the phase control signal, dynamically adjusts the DC support voltage, and outputs a DC control signal;

[0013] The magnetic force stabilization module receives the DC control signal, switches to the DC support mode, and provides an additional magnetic attraction force through the magnetic locking technology to stabilize the contact state of the contactor;

[0014] The status monitoring module receives the stability signal and judges whether the grid voltage has recovered;

[0015] The power supply recovery module receives the recovery signal, switches back to AC power supply according to the optimal phase calculated by the switching control module, avoids current impact, prevents contact vibration, completes the AC-DC switching, and restores the normal power supply state.

[0016] As a preferred solution of the anti-power-flicker device based on a magnetic switch according to the present invention, wherein:

[0017] The magnetic force stabilization module monitors the contact state and outputs a stability signal;

[0018] The magnetic locking technology is specifically a magnetic switch or an electromagnetic lock.

[0019] As a preferred solution of the anti-power-flicker device based on a magnetic switch according to the present invention, wherein: in the status monitoring module, when the voltage recovers to the set threshold and continuously operates stably for more than the preset time, a recovery signal is output.

[0020] In a second aspect, the present invention provides an anti-power-flicker method based on a magnetic switch, including,

[0021] Step S1, detecting the change of grid voltage and judging whether power flicker occurs; when the voltage is lower than the set threshold, outputting a power flicker signal;

[0022] Step S2, calculating the optimal AC-DC switching phase based on the power flicker signal and outputting a phase control signal;

[0023] Step S3, adjusting the DC support voltage according to the phase control signal and outputting a DC control signal;

[0024] Step S4: Receive the DC control signal, switch to the DC support mode, and stabilize the contact state through the magnetic locking technology to prevent contact vibration; meanwhile, monitor the contact state and output a stability signal.

[0025] Step S5: Receive the stability signal and determine whether the grid voltage has recovered; when the voltage recovers to be stable, output a recovery signal.

[0026] Step S6: Receive the recovery signal, switch back to AC power supply according to the optimal phase to avoid current impact and prevent contact vibration; after completing the AC-DC switching, resume normal power supply.

[0027] As a preferred solution of the anti-power-sag method based on a magnetic switch according to the present invention, wherein: the step of detecting the change of the grid voltage, determining whether a power sag occurs, and outputting a power-sag signal when the voltage is lower than the set threshold is as follows:

[0028] Define the collected grid voltage signal as V(t):

[0029] V(t) = {v 1 , v 2 , …, v n},

[0030] wherein, V(t) represents the grid voltage signal at time t, v i represents the voltage value at the i-th sampling point, n is the total number of sampling points, and t represents the current time point.

[0031] Apply a moving average filter to the sampling sequence, and the formula is:

[0032]

[0033] wherein, represents the smoothed voltage value with a window length of m, m represents the length of the moving window, v i represents the voltage value at the i-th sampling point, and t represents the current time point;

[0034] Calculate the frequency change by using the short-time Fourier transform STFT, perform the STFT transform on the signal, and the formula is:

[0035]

[0036] wherein, X(t, f) represents the amplitude of the short-time Fourier transform at time t and frequency f, v i is the voltage value at the i-th sampling point, w(i - t) is the window function, f is the analysis frequency, and j is the imaginary unit.

[0037] Calculate the voltage change rate, and extract the amplitude at the low-frequency component f = 0 based on the STFT, which is expressed as:

[0038] ΔV(t) = |X(t, 0)| - |X(t - 1, 0)|,

[0039] where ΔV(t) represents the instantaneous voltage change, and X(t, 0) and X(t - 1, 0) represent the amplitudes of the STFT low-frequency components at the current and previous moments respectively.

[0040] When the following conditions are met, it is determined that a power flicker has occurred:

[0041]

[0042] where V th is the set voltage threshold.

[0043] If the duration T d exceeds the set time threshold T th , then a power flicker signal is output:

[0044] When S d = 1,

[0045] where S d is the power flicker signal. When S d = 1, it indicates that a power flicker has been detected. T d represents the duration of low voltage, and T th is the set time threshold.

[0046] As a preferred solution of the anti-power-flicker method based on a magnetic switch according to the present invention, wherein: the step of calculating the optimal AC-DC switching phase based on the power flicker signal and outputting a phase control signal is as follows.

[0047] Collect the AC grid voltage signal, and define the time-domain expression of the grid voltage signal as:

[0048] V ac (t) = V m cos(ωt + φ),

[0049] where V ac (t) is the instantaneous voltage of the AC grid, V m is the maximum amplitude of the grid voltage, ω is the grid angular frequency, t is the current time, and φ is the current voltage phase.

[0050] Calculate the current phase based on the sampling signal, and the calculation formula is:

[0051]

[0052] where φ(t) represents the voltage phase at the current moment, and Δt is the sampling time interval.

[0053] Set the optimal AC-DC switching phase φ opt Minimize the switching impact, φ opt The calculation formula is:

[0054]

[0055] where φ opt is the optimal switching phase, V dc is the DC support voltage, |V ac (t) - V dc | is the AC-DC voltage difference,

[0056] Calculate the optimal switching moment, the formula is:

[0057]

[0058] where t opt is the optimal switching moment,

[0059] When t = t opt , S φ = 1, generate a phase control signal,

[0060] where S φ is the phase control signal, when S φ = 1, output a phase synchronization trigger signal.

[0061] As a preferred solution of the anti-power-sag method based on a magnetic switch described in the present invention, wherein: the step of adjusting the DC support voltage according to the phase control signal and outputting a DC control signal is,

[0062] The DC support voltage V dc needs to be dynamically adjusted to match the optimal AC-DC switching phase φ opt , and its adjustment formula is:

[0063] V dc (t) = αV ac (t opt ),

[0064] where V dc (t) is the DC support voltage at time t, α is the DC support ratio coefficient, 0 < α ≤ 1, set according to the load characteristics, V ac 9t opt ) is the AC voltage at the optimal switching moment t opt ,

[0065] For the DC support voltage, to avoid voltage mutation, use an exponential smoothing function to adjust V dc , and the adjustment formula is:

[0066] Vdc V(t) = λV dc (t - 1) + (1 - λ)αV ac (t opt )

[0067] Where λ is the smoothing factor (0 < λ < 1), which is used to control the adjustment rate of the DC support voltage.

[0068] When V dc reaches the steady state and the change amount is less than the set threshold ΔV th , the DC control signal is output:

[0069] When |V dc (t) - V dc (t - 1)| < ΔV th , S dc = 1,

[0070] Where S dc is the DC control signal. When S dc = 1, it indicates that the DC support voltage has reached the steady state, and ΔV th is the threshold value allowed for voltage change.

[0071] As a preferred solution of the anti - power - swaying method based on the magnetic switch described in the present invention, wherein: the step of switching to the DC support mode and stabilizing the contact state through the magnetic locking technology is as follows.

[0072] When S dc = 1, M s = 1. When receiving the DC control signal S dc = 1, switch to the DC support mode. Where M s is the DC support mode indication signal. When M s = 1, it means that the DC support mode has been switched.

[0073] Use the magnetic locking technology to enhance the contact stability. The magnetic suction calculation formula is:

[0074]

[0075] Where F m is the magnetic suction, β is the electromagnetic suction coefficient, and I dc is the DC support current, and the calculation formula is:

[0076] I dc = P / V dc , where P is the load power.

[0077] Monitor the contact state. Define the contact vibration state quantity as D c :

[0078]

[0079] Among them, D c is the contact vibration amount, reflecting the degree of change in the contact state, C(i) represents the contact position state at time i, and T w is the monitoring window length.

[0080] If the vibration amount is lower than the set threshold D th , output a stability signal:

[0081] When D c < D th , S s = 1,

[0082] Among them, S s is the contact stability signal. When S s = 1, it means that the contact has been stabilized.

[0083] As a preferred scheme of the anti - power - swaying method based on a magnetic switch described in the present invention, wherein: the step of receiving the stability signal and judging whether the grid voltage has recovered; when the voltage recovers stably and outputting a recovery signal is as follows,

[0084] Collect the grid voltage signal, and the grid voltage signal is expressed as V ac (t):

[0085] V ac (t)= V m cos(ωt + φ),

[0086] Among them, V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, and φ is the voltage phase.

[0087] Use the moving average method to calculate the voltage mean value, and the calculation formula is:

[0088]

[0089] Among them, is the voltage mean value at time t, and N is the moving window length.

[0090] Judge whether the voltage has recovered, set the voltage recovery threshold V th , when the following conditions are met, it is considered that the grid voltage has recovered:

[0091]

[0092] Among them, V th is the set recovery threshold.

[0093] To prevent misjudgment, a recovery time T is introduced. r , and the calculation formula is:

[0094]

[0095] Among them, T v is the cumulative time of voltage recovery, and T r is the set recovery time threshold.

[0096] When the voltage recovery time exceeds the threshold, T v >T r , S r =1, and a recovery signal is output. Among them, S r is the recovery signal. When S r =1, it indicates that the grid voltage has recovered to stability.

[0097] As a preferred solution of the anti - voltage - sag method based on a magnetic switch according to the present invention, wherein: the step of receiving the recovery signal and switching back to AC power supply according to the optimal phase is as follows.

[0098] Collect the current AC voltage phase information. The expression of the grid voltage is:

[0099] V ac (t)=V m cos(ωt + φ),

[0100] Among them, V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, and φ is the voltage phase.

[0101] The formula for calculating the phase at the current moment is:

[0102]

[0103] Among them, φ(t) is the voltage phase at time t, and Δt is the sampling time interval.

[0104] Calculate the optimal phase switching moment. The formula is:

[0105]

[0106] Among them, φ opt is the optimal switching phase, and V dc is the current DC support voltage.

[0107] Calculate the optimal switching moment. The calculation formula is:

[0108]

[0109] Among them, t swis the optimal phase switching moment,

[0110] When the recovery signal S r = 1 and reaches the optimal phase switching moment t = t sw , perform the switching:

[0111] When t = t sw and S r = 1, S ac = 1,

[0112] wherein, S ac is the AC switching trigger signal. When S ac = 1, perform the AC-DC switching,

[0113] When the AC switching is successful and the current impact is less than the set threshold I th , resume normal power supply:

[0114] When |I ac - I dc | < I th , M s = 0,

[0115] wherein, M s is the DC support mode status indication signal. M s = 0 indicates exiting the DC support mode. I ac is the AC current, I dc is the DC support current, and I th is the maximum threshold allowed for the current impact.

[0116] The beneficial effects of the present invention are as follows: In the present invention, moving average filtering is adopted to reduce the interference of instantaneous voltage fluctuations, and the short-time Fourier transform STFT is combined to extract the instantaneous changes of low-frequency components, so as to more accurately identify the power grid voltage drop, effectively avoiding the problems of misjudgment or missed judgment due to short-time fluctuations in the traditional method.

[0117] In the present invention, in the AC-DC switching strategy, the current voltage phase is calculated and the optimal switching phase is matched to ensure the minimum AC-DC voltage difference during switching, thereby reducing the current impact and avoiding the contact vibration of the contactor caused by phase deviation; at the same time, the exponential smoothing function is combined to dynamically adjust the DC support voltage, and the voltage changes more smoothly during the switching process; in the DC support mode, the magnetic locking technology is adopted to enhance the stability of the contactor contact, and by real-time monitoring the contact status quantity, the contact will not be mis-released due to the electromagnetic suction fluctuation during the power supply interruption.

[0118] In the present invention, for the judgment of grid voltage recovery, the sliding average is used to calculate the voltage mean value, combined with the cumulative calculation method of recovery time. The AC-DC switching is only executed after the voltage stability reaches the set threshold, so as to reduce the interference of short-term voltage fluctuations on the system and avoid misoperation caused by premature switching. During the power supply recovery process, the optimal phase matching switching moment is calculated, so that no excessive current impact will occur when the AC power supply is restored, and mechanical jitter of the contact due to instantaneous impact is avoided.

[0119] In summary, the present invention improves the stability of the contactor during power fluctuations, reduces the risk of mis-triggering, and effectively overcomes the deficiencies of traditional anti-power-fluctuation solutions in load adaptability, contact vibration suppression, and power supply switching smoothness. BRIEF DESCRIPTION OF THE DRAWINGS

[0120] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0121] Figure 1 It is a schematic framework diagram of an anti-power-fluctuation device based on a magnetic switch of the present invention.

[0122] Figure 2 It is a schematic flow diagram of an anti-power-fluctuation method based on a magnetic switch of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0123] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0124] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0125] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other with other embodiments.

[0126] Embodiment 1, referring to Figure 1 and Figure 2 , this embodiment provides an anti-power-fluctuation device based on a magnetic switch, including:

[0127] A voltage detection module, a switching control module, a DC support module, a magnetic force stabilization module, a status monitoring module, and a power supply restoration module;

[0128] The voltage detection module is used to detect changes in the grid voltage, determine whether voltage sags occur, and output a voltage sag signal when the voltage is lower than the set threshold;

[0129] The switching control module receives the voltage sag signal, calculates the optimal AC-DC switching phase, and outputs a phase control signal;

[0130] The DC support module receives the phase control signal, dynamically adjusts the DC support voltage, and outputs a DC control signal;

[0131] The magnetic force stabilization module receives the DC control signal, switches to the DC support mode, and provides an additional magnetic attraction force through the magnetic locking technology to stabilize the contact state of the contactor;

[0132] The magnetic force stabilization module monitors the contact state and outputs a stability signal;

[0133] The magnetic locking technology is specifically a magnetic switch or an electromagnetic lock;

[0134] The status monitoring module receives the stability signal and determines whether the grid voltage has been restored;

[0135] In the status monitoring module, when the voltage is restored to the set threshold and continuously operates stably for more than the preset time, a restoration signal is output;

[0136] The power supply restoration module receives the restoration signal, switches back to AC power supply according to the optimal phase calculated by the switching control module, avoids current impact, prevents contact vibration, completes the AC-DC switching, and restores the normal power supply state.

[0137] This embodiment also provides a voltage sag resistance method for the above voltage sag resistance device based on a magnetic switch, including:

[0138] Step S1, detecting changes in the grid voltage and determining whether voltage sags occur; when the voltage is lower than the set threshold, output a voltage sag signal;

[0139] The steps of detecting changes in the grid voltage, determining whether voltage sags occur, and outputting a voltage sag signal when the voltage is lower than the set threshold are,

[0140] Define the collected grid voltage signal as V(t):

[0141] V(t) = {v 1 , v 2 , …, v n},

[0142] where V(t) represents the grid voltage signal at time t, and v irepresents the voltage value of the i-th sampling point, n is the total number of sampling points, t represents the current time point,

[0143] Apply a moving average filter to the sampling sequence, and the formula is:

[0144]

[0145] where, represents the smoothed voltage value with a window length of m, m represents the length of the moving window, v i represents the voltage value of the i-th sampling point, t represents the current time point;

[0146] Use the short-time Fourier transform STFT to calculate the frequency change. Perform the STFT transform on the signal, and the formula is:

[0147]

[0148] where, X(t,f) represents the amplitude of the short-time Fourier transform at time t and frequency f, v i is the voltage value of the i-th sampling point, w(i - t) is the window function, f is the analysis frequency, j is the imaginary unit,

[0149] Calculate the voltage change rate. Based on the STFT, extract the amplitude at the low-frequency component f = 0, which is expressed as:

[0150] ΔV(t) = |X(t,0)| - |X(t - 1,0)|,

[0151] where, ΔV(t) represents the instantaneous voltage change, and X(t,0) and X(t - 1,0) respectively represent the amplitudes of the STFT low-frequency components at the current and previous moments,

[0152] When the following conditions are met, it is determined that a voltage dip has occurred:

[0153]

[0154] where, V th is the set voltage threshold,

[0155] If the duration T d exceeds the set time threshold T th , then output a voltage dip signal:

[0156] When

[0157] where, S d is the voltage dip signal. When S d = 1, it means that a voltage dip is detected. T d represents the duration of the low voltage, T this the set time threshold,

[0158] Specifically, the sliding window filtering method is used to smooth the original voltage signal, reducing the interference of instantaneous fluctuations on the judgment. Subsequently, the short-time Fourier transform (STFT) is used to perform time-frequency analysis on the voltage signal, extracting the instantaneous change information of the low-frequency component, thereby obtaining more accurate voltage change characteristics and improving the detection robustness. Here, the voltage threshold V th and the time threshold T th are defined. Only when the voltage is lower than the set threshold and the duration exceeds the set threshold, the power swing signal S d is output to prevent misjudgment;

[0159] Step S2: Calculate the optimal AC-DC switching phase based on the power swing signal and output a phase control signal;

[0160] The steps of calculating the optimal AC-DC switching phase based on the power swing signal and outputting a phase control signal are as follows:

[0161] Collect the AC grid voltage signal. Define the time-domain expression of the grid voltage signal as:

[0162] V ac (t) = V m cos(ωt + φ),

[0163] where V ac (t) is the instantaneous voltage of the AC grid, V m is the maximum amplitude of the grid voltage, ω is the grid angular frequency, t is the current time, and φ is the current voltage phase.

[0164] Calculate the current phase based on the sampling signal. The calculation formula is:

[0165]

[0166] where φ(t) represents the voltage phase at the current moment, and Δt is the sampling time interval.

[0167] Set the optimal AC-DC switching phase φ opt to minimize the switching impact. The calculation formula of φ opt is:

[0168]

[0169] where φ opt is the optimal switching phase, V dc is the DC support voltage, |V ac (t) - V dc | is the AC-DC voltage difference.

[0170] Calculate the optimal switching moment. The formula is:

[0171]

[0172] Among them, t opt is the optimal switching moment,

[0173] When t = t opt , S φ = 1, a phase control signal is generated.

[0174] Among them, S φ is the phase control signal. When S φ = 1, a phase synchronization trigger signal is output.

[0175] Specifically, based on the time-domain expression of the grid AC voltage signal, the current phase information is calculated by sampling, and on this basis, the optimal AC-DC switching phase φ opt is determined to minimize the switching impact of the AC-DC voltage. The optimal switching moment t opt is calculated based on the current phase information and is used to trigger the phase control signal S φ , ensuring the stability of the AC-DC switching process and improving the reliability of the anti-sag system;

[0176] Step S3: Adjust the DC support voltage according to the phase control signal and output a DC control signal;

[0177] Step S4: Receive the DC control signal, switch to the DC support mode, and stabilize the contact state through magnetic locking technology to prevent contact vibration; at the same time, monitor the contact state and output a stability signal;

[0178] The step of adjusting the DC support voltage according to the phase control signal and outputting a DC control signal is as follows:

[0179] The DC support voltage V dc needs to be dynamically adjusted to match the optimal AC-DC switching phase φ opt , and its adjustment formula is:

[0180] V dc (t) = αV ac (t opt ),

[0181] Among them, V dc (t) is the DC support voltage at time t, α is the DC support ratio coefficient, 0 < α ≤ 1, which is set according to the load characteristics, and V ac (t opt ) is the AC voltage at the optimal switching moment t opt .

[0182] For the DC support voltage, to avoid voltage mutation, an exponential smoothing function is used to adjust Vdc , the adjustment formula is:

[0183] V dc (t) = λV dc (t - 1) + (1 - λ)αV ac (t opt ),

[0184] where λ is the smoothing factor (0 < λ < 1), used to control the adjustment rate of the DC support voltage,

[0185] When V dc reaches the steady state and the change amount is less than the set threshold ΔV th , the DC control signal is output:

[0186] When |V dc (t) - V dc (t - 1)| < ΔV th , S dc = 1,

[0187] where S dc is the DC control signal. When S dc = 1, it indicates that the DC support voltage has reached the steady state, and ΔV th is the threshold allowed for voltage change,

[0188] The steps to switch to the DC support mode and stabilize the contact state through the magnetic locking technology are as follows:

[0189] When S dc = 1, M s = 1. When receiving the DC control signal S dc = 1, switch to the DC support mode. Among them, M s is the DC support mode indication signal. When M s = 1, it means that the DC support mode has been switched,

[0190] Use the magnetic locking technology to enhance the contact stability. The magnetic suction force calculation formula is:

[0191]

[0192] where F m is the magnetic suction force, β is the electromagnetic suction coefficient, and I dc is the DC support current. The calculation formula is:

[0193] I dc = P / V dc , where P is the load power,

[0194] Monitor the contact state. Define the contact vibration state quantity as D c :

[0195]

[0196] Among them, D c is the contact vibration amount, reflecting the degree of change in the contact state, C(i) represents the contact position state at time i, and T w is the monitoring window length,

[0197] If the vibration amount is lower than the set threshold D th , output a stability signal:

[0198] When D c < D th , S s = 1,

[0199] Among them, S s is the contact stability signal. When S s = 1, it indicates that the contact has stabilized,

[0200] Specifically, in the DC support mode, according to the optimal switching phase φ opt calculate the adaptive DC support voltage V dc , and adopt exponential smoothing adjustment to ensure the smoothness of the voltage switching process; when V dc reaches stability, generate a DC control signal S dc , trigger the start of the DC support mode M s , and at the same time apply a magnetic suction force F m through magnetic locking technology to enhance the stability of the contact and prevent contact vibration; finally, based on the contact vibration state quantity D c carry out real-time monitoring. When the contact state tends to be stable, output the stability signal S s ;

[0201] Step S5, receive the stability signal and judge whether the grid voltage has recovered; when the voltage recovers and stabilizes, output a recovery signal;

[0202] The steps of receiving the stability signal and judging whether the grid voltage has recovered; when the voltage recovers and stabilizes, output a recovery signal are,

[0203] Collect the grid voltage signal, and the grid voltage signal is expressed as V ac (t):

[0204] V ac (t)= V m cos(ωt + φ),

[0205] Among them, V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, and φ is the voltage phase,

[0206] The sliding average method is used to calculate the average voltage, and the calculation formula is:

[0207]

[0208] Wherein, is the average voltage at time t, N is the length of the sliding window,

[0209] Judge whether the voltage has recovered, and set the voltage recovery threshold V th . When the following conditions are met, it is considered that the grid voltage has recovered:

[0210]

[0211] Wherein, V th is the set recovery threshold,

[0212] To prevent misjudgment, the recovery time T r is introduced, and the calculation formula is:

[0213]

[0214] Wherein, T v is the cumulative time of voltage recovery, T r is the set recovery time threshold,

[0215] When the voltage recovery time exceeds the threshold, T v >T r , S r = 1, and the recovery signal is output. Wherein, S r is the recovery signal. When S r = 1, it means that the grid voltage has recovered and stabilized;

[0216] Specifically, the average voltage is calculated based on the sliding average here to determine whether the grid voltage has recovered, ensuring that short-term fluctuations will not cause misjudgment. Secondly, the recovery threshold V th is set to judge whether the voltage has recovered. Further, through the cumulative calculation of the recovery time T r , the voltage stability is improved; when the recovery time exceeds the threshold T r , the recovery signal S r is output;

[0217] Step S6, receive the recovery signal, switch back to AC power supply according to the optimal phase, avoid current impact, and prevent contact vibration; after completing the AC-DC switching, resume normal power supply;

[0218] The steps of receiving the recovery signal and switching back to AC power supply according to the optimal phase are

[0219] Collect the current AC voltage phase information. The expression of the grid voltage is:

[0220] V ac (t) = V m cos(ωt + φ),

[0221] where V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, and φ is the voltage phase,

[0222] The phase calculation formula at the current moment is:

[0223]

[0224] where φ(t) is the voltage phase at time t, and Δt is the sampling time interval,

[0225] Calculate the optimal phase switching moment. The formula is:

[0226]

[0227] where φ opt is the optimal switching phase, and V dc is the current DC support voltage,

[0228] Calculate the optimal switching moment. The calculation formula is:

[0229]

[0230] where t sw is the optimal phase switching moment,

[0231] When the recovery signal S r = 1 and the optimal phase switching moment t = t sw is reached, perform the switching:

[0232] When t = t sw and S r = 1, S ac = 1,

[0233] where S ac is the AC switching trigger signal. When S ac = 1, perform the AC-DC switching,

[0234] When the AC switching is successful and the current impact is less than the set threshold I th , resume normal power supply:

[0235] When |I ac - I dc | < I th , M s= 0,

[0236] wherein, M s is the DC support mode status indication signal, M s = 0 indicates exiting the DC support mode, I ac is the AC current, I dc is the DC support current, I th is the maximum threshold allowed for current impact,

[0237] Specifically, after the AC power grid is restored, it is necessary to perform AC-DC switching at the optimal phase φ opt to reduce current impact. Here, calculate the current phase φ(t) and match the optimal switching moment t sw , to ensure smooth switching; when the restoration signal S r triggers and the system reaches the optimal switching phase, output the AC switching signal S ac , complete the switching from the DC support mode to AC power supply, and ensure that the current impact |I ac - I dc | is lower than the set threshold I th , to prevent contact vibration and equipment damage.

[0238] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An anti-electrical shaking device based on a magnetic switch, characterized in that: The device includes a voltage detection module, a switching control module, a DC support module, a magnetic stabilization module, a state monitoring module and a power supply recovery module: The voltage detection module is used to detect changes in grid voltage, determine whether power fluctuations occur, and output a power fluctuation signal when the voltage is lower than a set threshold; The switching control module receives the power shaking signal, calculates the optimal AC / DC switching phase, and outputs a phase control signal; The DC support module receives a phase control signal, dynamically adjusts the DC support voltage, and outputs a DC control signal; The magnetic stabilization module receives a DC control signal, switches to a DC support mode, and provides additional magnetic attraction force through magnetic locking technology to stabilize the contact state of the contactor; The state monitoring module receives the stability signal and determines whether the grid voltage has recovered; The power supply recovery module receives the recovery signal, switches back to AC power supply according to the optimal phase calculated by the switching control module, completes AC / DC switching, and recovers the normal power supply state.

2. The anti-electrical shaking device based on a magnetic switch according to claim 1, characterized in that: The magnetic force stabilization module monitors the contact state and outputs a stability signal; The magnetic locking technology is specifically a magnetic switch or an electromagnetic lock.

3. The anti-electrical shaking device based on a magnetic switch according to claim 2, characterized in that: In the state monitoring module, when the voltage recovers to the set threshold and continues to operate stably for more than a preset time, a recovery signal is output.

4. A method for preventing electric sway based on a magnetic switch, based on the anti-electric sway device based on a magnetic switch according to any one of claims 1 to 3, characterized in that: include: Step S1, detecting grid voltage changes and determining whether power shaking occurs; When the voltage is lower than the set threshold, a power shake signal is output; Step S2, calculating the optimal AC / DC switching phase based on the power shaking signal, and outputting a phase control signal; Step S3, adjusting the DC support voltage according to the phase control signal, and outputting a DC control signal; Step S4, receiving a DC control signal, switching to a DC support mode, and stabilizing the contact state through magnetic locking technology to prevent contact vibration; monitoring the contact state and outputting a stability signal; Step S5, receiving a stability signal and determining whether the grid voltage has recovered; when the voltage recovers to be stable, outputting a recovery signal; Step S6, receiving a recovery signal, switching back to AC power supply according to the optimal phase, and restoring normal power supply after completing the AC-DC switching.

5. The anti-electricity shaking method based on a magnetic switch according to claim 4, characterized in that: The step of detecting the grid voltage change and determining whether power shaking occurs, and outputting a power shaking signal when the voltage is lower than a set threshold, is as follows: The collected grid voltage signal is defined as V(t): V(t)={v1,v2,…,v n }, Where V(t) represents the grid voltage signal at time t, v i represents the voltage value of the i-th sampling point, n is the total number of sampling points, t represents the current time point, Apply a sliding average filter to the sample sequence, the formula is: in, represents the smoothed voltage value with a window length of m, where m represents the length of the sliding window, and v i represents the voltage value of the i-th sampling point, and t represents the current time point; The short-time Fourier transform (STFT) is used to calculate the frequency change, and the STFT transform is performed on the signal. The formula is: Where X(t,f) represents the short-time Fourier transform amplitude at time t and frequency f, v i is the voltage value of the i-th sampling point, w(it) is the window function, f is the analysis frequency, j is the imaginary unit, Calculate the voltage change rate and extract the amplitude of the low-frequency component at f=0 based on STFT, expressed as: ΔV(t)=|X(t,0)|-|X(t-1,0)|, Among them, ΔV(t) represents the instantaneous change of voltage, X(t,0) and X(t-1,0) represent the amplitude of the STFT low-frequency component at the current and previous moments respectively. When the following conditions are met, it is determined that a power surge has occurred: Among them, V th is the set voltage threshold, like Duration T d Exceeding the set time threshold T th , then the output power shaking signal: when Among them, S d For power shaking signal, when S d =1, it means that power shaking is detected, T d Indicates the duration of low voltage, T th The time threshold is set.

6. The anti-electricity shaking method based on a magnetic switch according to claim 5, characterized in that: The steps of calculating the optimal AC / DC switching phase based on the power shaking signal and outputting the phase control signal are as follows: Collect the AC grid voltage signal and define the grid voltage signal time domain expression as: V ac (t)=V m cos(ωt+φ), Among them, V ac (t) is the instantaneous voltage of the AC grid, V m is the maximum amplitude of the grid voltage, ω is the grid angular frequency, t is the current time, φ is the current voltage phase, The current phase is calculated based on the sampled signal. The calculation formula is: Among them, φ(t) represents the voltage phase at the current moment, Δt is the sampling time interval, Set the optimal AC / DC switching phase φ opt Minimize switching shock, φ opt The calculation formula is: Among them, φ opt is the optimal switching phase, V dc is the DC support voltage, |V ac (t)-V dc | is the AC / DC voltage difference, Calculate the optimal switching time, the formula is: Among them, t opt is the optimal switching time, When t = t opt , S φ =1, generate phase control signal, Among them, S φ is the phase control signal, when S φ =1, output phase synchronization trigger signal.

7. The anti-electricity shaking method based on a magnetic switch according to claim 6, characterized in that: The steps of adjusting the DC support voltage according to the phase control signal and outputting the DC control signal are: DC support voltage V dc Dynamic adjustment is required to match the optimal AC / DC switching phase φ opt , the adjustment formula is: V dc (t)=αV ac (t opt ), Among them, V dc (t) is the DC support voltage at time t, α is the DC support proportional coefficient, 0<α≤1, set according to the load characteristics, V ac (t opt ) is the optimal switching time t opt The AC voltage, For the DC support voltage, an exponential smoothing function is used to adjust V dc , the adjustment formula is: V dc (t)=λV dc -1)+(1-λ)αV ac (t opt ), Among them, λ is a smoothing factor (0<λ<1), which is used to control the adjustment rate of the DC support voltage. When V dc Reaching a stable state, the change is less than the set threshold ΔV th When , the output DC control signal is: When |V dc (t)-V dc (t-1)|<ΔV th , S dc =1, Among them, S dc is the DC control signal, when S dc =1, indicating that the DC support voltage has reached a stable state, ΔV th The threshold for voltage change allowed.

8. The anti-electricity shaking method based on a magnetic switch according to claim 7, characterized in that: The steps of switching to the DC support mode and stabilizing the contact state by magnetic locking technology are: When S dc =1,M s =1, when receiving the DC control signal S dc =1, switch to DC support mode, where M s It is the DC support mode indication signal. s =1, it means it has switched to DC support mode. Magnetic locking technology is used to enhance contact stability. The formula for calculating the magnetic attraction force is: Among them, F m is the magnetic attraction force, β is the electromagnetic attraction coefficient, I dc is the DC support current, and the calculation formula is: I dc =P / V dc , where P is the load power, Monitor the contact state and define the contact vibration state quantity as D c : Among them, D c is the contact vibration amount, reflecting the degree of change of the contact state, C(i) represents the contact position state at time i, T w To monitor the window length, If the vibration level is lower than the set threshold D th , output stability signal: When D c <D th , S s =1, Among them, S s is the contact stability signal. s =1, indicating that the contact is stable.

9. The anti-electricity shaking method based on a magnetic switch according to claim 8, characterized in that: The steps of receiving the stability signal and judging whether the grid voltage has recovered; and outputting the recovery signal when the voltage has recovered and stabilized are as follows: Collect the grid voltage signal, which is represented by V ac (t): V ac (t)=V m cos(ωt+φ), Among them, V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, φ is the voltage phase, The voltage mean is calculated using the sliding average method, and the calculation formula is: in, is the voltage mean at time t, N is the sliding window length, Determine whether the voltage has recovered and set the voltage recovery threshold V th , when the following conditions are met, the grid voltage is considered to be restored: Among them, V th is the recovery threshold set, To prevent misjudgment, the recovery time T is introduced r , the calculation formula is: Among them, T v is the cumulative time of voltage recovery, T r is the recovery time threshold set. When the voltage recovery time exceeds the threshold, T v >T r , S r =1, output recovery signal, where S r To restore the signal, when S r =1, it indicates that the grid voltage has returned to stability.

10. The anti-electricity shaking method based on a magnetic switch according to claim 9, characterized in that: The steps of receiving the recovery signal and switching back to AC power supply according to the optimal phase are: Collect the current AC voltage phase information, the expression of the grid voltage is: V ac (t)=V m cos(ωt+φ), Among them, V ac (t) is the AC voltage at time t, V m is the maximum voltage amplitude, ω is the grid angular frequency, φ is the voltage phase, The phase calculation formula at the current moment is: Among them, φ(t) is the voltage phase at time t, Δt is the sampling time interval, Calculate the optimal phase switching time, the formula is: Among them, φ opt is the optimal switching phase, V dc is the current DC support voltage, Calculate the optimal switching time, the calculation formula is: Among them, t sw is the optimal phase switching time, When receiving the recovery signal S r =1 and the optimal phase switching time t=t sw When the switch is executed: When t = t sw And S r =1, S ac =1, Among them, S ac is the AC switching trigger signal. ac =1, AC / DC switching is performed. When the AC switching is successful and the current impact is less than the set threshold I th When the power supply is restored to normal: This |I ac -I dc | th , M s = 0,​ Among them, M s It is the DC support mode status indication signal, M s =0 means exiting DC support mode, I ac is the alternating current, I dc is the DC support current, I th It is the maximum threshold allowed for current surge.

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