High-voltage reactor direct-current resistance measuring device integrated with shielding device

Abstract

The invention discloses a high-voltage reactor direct-current resistance measuring device integrated with a shielding device, and relates to the technical field of reactor direct-current resistance measurement. Comprising a shielding device and a measuring device. The measuring device comprises a direct current generator, a bypass resistor and a multi-order LC filter which are electrically connected with the high-voltage reactor, a current and voltage measuring circuit which is electrically connected with the bypass resistor and the multi-order LC filter, and an MCU control circuit which is electrically connected with the current and voltage measuring circuit. The shielding device is of a cover body structure and comprises internal insulating layers which are arranged layer by layer from outside to inside; the high-conductivity metal layer, the middle insulating layer, the high-permeability magnetic shielding layer and the internal insulating layer are detachably connected with the high-voltage reactor; the shielding device covers the measuring device and the high-voltage reactor, so that the measuring device and the high-voltage reactor are in a sealed state. The device can effectively suppress induced electric interference and reduce the influence of alternating current components on a measurement result, so that the accuracy and reliability of direct current resistance data are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of reactor direct current resistance measurement, and in particular to a high-voltage reactor direct current resistance measurement device integrated with a shielding device. Background Art

[0002] In the operation and maintenance of power systems, accurately measuring the DC resistance of equipment is a crucial task, especially in high-voltage power equipment such as 500kV substations. The measurement of DC resistance can not only reflect the working status of electrical equipment, but also help to detect potential faults in a timely manner. However, in the actual measurement process, the induced electrical signals in the environment often have a significant impact on the measurement results, especially in the operating environment of large power equipment, where changes in electric and magnetic fields will produce instantaneous induced electricity.

[0003] For example, when measuring the interval of a 500kV line and testing the circuit resistance of a circuit breaker, the instantaneous induced current to which the measuring equipment is subjected can reach 2000V. This high-intensity induced current may not only damage the measuring equipment, but also pose a serious threat to the safety of the operator. At the same time, when measuring the reactor on the low-voltage side of a 500kV main transformer, if the reactor adjacent to the device under test is in operation, the induced current may reach 800V, further deteriorating the reliability of the measurement.

[0004] At present, the commonly used DC resistance test devices are not equipped with effective inductive electrical shielding protection devices, which makes DC resistance measurement in high-voltage environments face huge challenges. Due to inductive electrical interference, the measured DC resistance value often has a large error, which not only affects the accuracy of equipment maintenance, but also reduces the overall safety of the power system.

[0005] When measuring the DC resistance of reactors in power systems, the following technical issues need to be solved urgently:

[0006] Interference from inductive current: When measuring near high-voltage equipment, strong electric and magnetic fields will cause inductive current to be generated, making the measuring instrument unable to provide accurate DC resistance values. This inductive current will not only affect the accuracy of the measurement, but also damage the test equipment.

[0007] Mixing of measurement signals: During the measurement process, strong interfering AC components may appear in the windings of the reactor. These components are mixed into the measurement signal, increasing the difficulty of extracting the DC components.

[0008] The existing equipment has insufficient anti-interference ability: Traditional measurement equipment lacks effective shielding and filtering design, which makes it difficult to achieve accurate DC resistance measurement in an environment with induced electricity. Frequent equipment damage also causes economic losses.

[0009] Safety hazards: High-intensity induced electricity may cause electric shock risks to operators, so a safe measurement method is needed to ensure the personal safety of operators when performing reactor DC resistance tests. Summary of the invention

[0010] In view of the above problems, the present invention proposes a DC resistance measuring device with a shielding effect; the device can effectively suppress induced electrical interference and reduce the influence of AC components on the measurement results, thereby ensuring the accuracy and reliability of DC resistance data.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A high-voltage reactor DC resistance measuring device integrated with a shielding device, the high-voltage reactor DC resistance measuring device comprising a shielding device and a measuring device;

[0013] The measuring device comprises a DC current generator, a bypass resistor and a multi-order LC filter electrically connected to the high-voltage reactor, wherein the bypass resistor and the multi-order LC filter form a parallel relationship, a current and voltage measuring circuit electrically connected to the bypass resistor and the multi-order LC filter, and an MCU control circuit electrically connected to the current and voltage measuring circuit;

[0014] The shielding device is a cover structure, including an internal insulation layer arranged layer by layer from the outside to the inside; a high-conductivity metal layer, a middle insulation layer, a high-permeability magnetic shielding layer and an internal insulation layer, which is detachably connected to the high-voltage reactor; the shielding device covers the measuring device and the high-voltage reactor, so that the measuring device and the high-voltage reactor are in a sealed state.

[0015] Furthermore, the high-voltage reactor DC resistance measuring device generates a specified DC current through a DC current generator and supplies it to the reactor; the reactor generates a voltage drop, and the bypass resistor bypasses the AC interference; the multi-order LC filter further filters the AC component and outputs a pure voltage signal; the current and voltage measurement circuit measures the voltage and current data of the reactor and sends it to the MCU control circuit; the MCU processes the data, extracts the effective DC component and calculates the DC resistance of the reactor.

[0016] Furthermore, the DC current generator adopts a BUCK step-down constant current circuit to reduce the input voltage to a lower output voltage and stably provide a DC current of 0-20A; the DC current generator includes a main switch tube, an optocoupler and a gate driver, a freewheeling diode, a filter, and a current sensor.

[0017] Furthermore, the DC current generator drives the main switch tube to turn on through the optocoupler and the gate driver chip based on the PWM signal; when the main switch tube is driven to turn on, the power supply supplies power to the load, and the inductor stores energy and charges the capacitor at the same time; when the main switch tube is turned off, the inductor current cannot change suddenly, and the freewheeling diode provides a freewheeling path to complete a working cycle; the DC current generator further smoothes the output current through the second-order filtering combination of the filter, and supplies power to the inductor under test; the Hall current sensor collects the output current in real time and outputs it to the microcontroller MCU through the analog-to-digital converter ADC.

[0018] Furthermore, the current and voltage measurement circuit includes a DC voltage acquisition circuit; the input signal of the DC voltage acquisition circuit is derived from the voltage signal at both ends of the high-voltage reactor, and the DC voltage acquisition circuit uses a small-resistance resistor and a capacitor for preliminary processing to eliminate most interference signals; the signal is further processed by a multi-stage filter composed of an inductor and a capacitor to remove residual high-frequency interference signals; the signal after filtering is sent to an isolation operational amplifier for signal isolation and amplification to isolate the interference between the subsequent circuit and the front-end circuit; finally, the amplified and isolated signal is output from the analog-to-digital converter ADC to the microcontroller MCU.

[0019] Furthermore, the MCU control circuit uses a STM32F446 high-performance 32-bit microcontroller MCU as the core, which has hard floating points and a digital signal processing unit DSP, and supports a fast Fourier transform FFT algorithm;

[0020] The microcontroller MCU outputs a PWM signal through the PWM pin to drive the MOSFET switch to control the on and off of the current; the output current is controlled by adjusting the duty cycle of the PWM signal; the processed current and voltage signals are input to the MCU and converted through the analog-to-digital converter ADC; the fast Fourier transform algorithm is applied in the microcontroller MCU to perform digital filtering and separate the DC voltage and current signals; finally, the separated signal is used to calculate the DC resistance of the reactor coil.

[0021] Furthermore, the microcontroller MCU distinguishes the signal characteristics of different frequency bands through wavelet transform, wavelet packet transform and Fourier transform, and identifies and classifies interference signals;

[0022] The microcontroller MCU uses an adaptive filter to perform an adaptive filtering algorithm to dynamically adjust filtering parameters, automatically identify and remove induced electricity and noise signals from reactors, surrounding power lines and other electrical equipment;

[0023] The microcontroller MCU performs adaptive noise elimination on each signal channel, using the difference between the main signal and the reference signal to estimate and eliminate noise; by analyzing the time domain characteristics and spectral characteristics of the signal, it can dynamically remove irrelevant noise components;

[0024] After the above algorithm processing, the DC voltage and current signals are filtered out separately, ensuring that the measuring device correctly measures the DC resistance of the high-voltage reactor.

[0025] Furthermore, the microcontroller MCU analyzes the time-frequency characteristics of the signal by decomposing the signal into different frequency bands based on wavelet transform;

[0026] The calculation formula of wavelet transform is as follows:

[0027]

[0028] Where W(a,b) is the wavelet transform coefficient, which represents the projection value of the signal at scale a and position b; x(t) is the input signal; is the complex conjugate of the mother wavelet function; is the mother wavelet function; a is the scale parameter, which controls the frequency resolution; b is the time shift parameter, which controls the time position; t is the time variable;

[0029] The microcontroller MCU further decomposes the detail part based on the wavelet decomposition based on the wavelet packet transform to obtain a higher frequency resolution;

[0030] The calculation formula of wavelet decomposition is as follows:

[0031]

[0032]

[0033] Where W j,k (t) is the coefficient of the kth node in the jth layer; W j+1,2k (t) is the low-frequency component of the 2kth node in the j+1th layer; W j+1,2k+1 (t) is the high-frequency component of the 2k+1th node in the j+1th layer;

[0034] h(n) and g(n) are low-pass and high-pass filters; n is the discrete sample point index; t is the time variable;

[0035] The microcontroller MCU converts the signal from the time domain to the frequency domain through Fourier transform to analyze the frequency components;

[0036] The calculation formula of Fourier transform is as follows:

[0037]

[0038] In the formula, X(f) is the spectrum of the signal in the frequency domain; x(t) is the original signal; e -j2πft is a complex exponential function; dt is a small change in the integral variable t; f is the frequency; j is the imaginary unit.

[0039] Further, the adaptive filtering algorithm includes an LMS algorithm and an RLS algorithm;

[0040] The LMS algorithm updates the filter weights using the minimum mean square error criterion. The calculation formula is as follows:

[0041] Output signal:

[0042]

[0043] error:

[0044] e(n)=d(n)-y(n)

[0045] Weight update:

[0046] w i (n+1)=w i (n)+2μe(n)x(n-1)

[0047] Where y(n) is the filter output; M is the filter order; w i (n) is the ith weight of the filter, the filter weight value updated at time n; x(ni) is the value of the input signal at time ni; e(n) is the error signal; d(n) is the desired signal; w i (n+1) is the i-th weight value at time n+1; μ is the step size factor, which controls the speed of weight adjustment; 2μe(n)x(n-1) is the amount of weight update;

[0048] The RLS algorithm updates the filter weights based on the recursive least squares criterion, and the calculation formula is as follows:

[0049] Gain vector:

[0050]

[0051] error:

[0052] e(n)=d(n)-w T (n-1)x(n)

[0053] Weight update:

[0054] w(n)=w(n-1)+K(n)e(n)

[0055] Inverse covariance matrix update:

[0056]

[0057] Where K(n) is the gain vector; P(n-1) is the inverse covariance matrix at time n-1; x(n) is the input signal vector; λ is the forget factor, which controls the update speed of the weight; x T (n) is the transpose of the input signal vector x(n); e(n) is the error signal; d(n) is the desired signal; w T (n-1) is the transpose of the weight vector w(n-1) at time n-1; w(n) is the weight vector; P(n) is the inverse covariance matrix; λ is the forget factor, which controls the update speed of the weight; P(n-1) is the inverse covariance matrix at time n-1;

[0058] The steps of the adaptive filtering algorithm are as follows:

[0059] Step 1: The reference signal x(n) enters the adaptive filter to generate the estimated noise n(n);

[0060] Step 2, main signal x s (n) minus the estimated noise to obtain the pure signal y(n):

[0061] y(n)=x s (n)-n(n)

[0062] Step 3, update the filter parameters to minimize the error:

[0063] e(n)=x s (n)-y(n)

[0064] Adjust filter weights according to the LMS algorithm and the RLS algorithm.

[0065] The high-voltage reactor DC resistance measuring device with shielding device has the following beneficial effects:

[0066] Suppressing inductive interference: The shielding device effectively reduces the influence of external electromagnetic interference, thereby improving the accuracy and reliability of measurement. This is especially important for high-voltage measurement environments and helps to obtain more realistic measurement data.

[0067] Reduce AC component interference: The use of multi-order LC filters can further filter the AC components, making the output signal purer and significantly reducing the interference of AC signals on DC resistance measurement results.

[0068] Improve measurement accuracy: Through precisely controlled DC current generation and real-time current and voltage measurement, combined with the MCU's digital signal processing algorithm, the DC component can be extracted more accurately, thereby improving the measurement accuracy of DC resistance.

[0069] Dynamic noise elimination: The microcontroller MCU uses an adaptive filtering algorithm to dynamically adjust the filtering parameters according to the real-time detection situation, effectively identify and remove noise from different sources, and ensure the validity of the measurement data.

[0070] Simplified operation process: The integrated design reduces the need for external devices, making the overall operation easier and improving the user experience.

[0071] Improve the adaptability of the equipment: Due to its strong anti-interference ability, it can maintain good measurement performance in different power environments, making the device suitable for a variety of complex industrial applications.

[0072] Enhanced safety: The closed shielding structure not only reduces external interference, but also provides additional safety protection during high-voltage operation, preventing accidental contact with high-voltage components.

[0073] In summary, the high-voltage reactor DC resistance measuring device integrated with the shielding device ensures the accuracy, reliability and safety of DC resistance measurement and enhances the overall performance of the high-voltage reactor measurement equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0075] Figure 1 It is a schematic diagram of the overall structure of the device for measuring the DC resistance of a high-voltage reactor according to the present invention;

[0076] Figure 2 A circuit diagram of a DC current generator of a measuring device of the present invention;

[0077] Figure 3 A circuit diagram of a DC voltage acquisition circuit of a measuring device of the present invention;

[0078] Figure 4 A circuit diagram of the MCU control circuit of the present invention;

[0079] Figure 5 It is a schematic structural diagram of the shielding device of the present invention;

[0080] In the figure: 1. High conductivity metal layer; 2. Middle insulation layer; 3. High magnetic permeability magnetic shielding layer; 4. Internal insulation layer. DETAILED DESCRIPTION

[0081] The following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0082] In view of the problem that when measuring the DC resistance of an online high-voltage reactor in a power system, the induction signal interference generated by nearby high-voltage reactors and other equipment causes a large error in the measurement result, this embodiment provides a high-voltage reactor DC resistance measuring device with an integrated shielding device, and the high-voltage reactor DC resistance measuring device includes a measuring device;

[0083] like Figure 1 As shown, the measuring device includes a DC current generator electrically connected to the high-voltage reactor, a bypass resistor and a multi-order LC filter, wherein the bypass resistor and the multi-order LC filter form a parallel relationship, a current and voltage measuring circuit electrically connected to the bypass resistor and the multi-order LC filter, and an MCU control circuit electrically connected to the current and voltage measuring circuit.

[0084] Among them, the main function of the DC current generator is to generate a stable DC current and supply it to the high-voltage reactor to be measured. The functions of the bypass resistor are: 1. Suppress AC interference: By bypassing the AC component, it prevents it from interfering with the measurement of the high-voltage reactor, thereby improving the accuracy of the measurement; 2. Shunt effect: Provide a low impedance path for the AC signal to ensure that the AC interference does not affect the DC current measurement of the reactor. The functions of the multi-order LC filter are: 1. Signal filtering: Use a combination of inductance and capacitance to remove high-frequency AC components, retain only DC components, and provide a purer voltage signal; 2. Stability: Through the design of multi-order filtering, the fluctuation of the output signal is reduced to avoid measurement errors caused by signal fluctuations. The functions of the current and voltage measurement circuit are: 1. Signal acquisition: Collect voltage signals from both ends of the high-voltage reactor and obtain current data in real time. 2. Signal processing: Preliminary processing of the signal through small resistance resistors and capacitors to eliminate most of the interference, and use multi-stage filters to further remove residual high-frequency noise. 3. Isolation and amplification: The signal is processed by the isolation operational amplifier to improve the signal quality and ensure the accuracy of the subsequent ADC.

[0085] Specifically, Figure 2As shown, the DC current generator is designed based on the BUCK circuit. The BUCK circuit is a step-down DC-DC converter that can reduce the input high voltage to a lower output voltage and can stably provide a certain output current. The DC current generator includes: the main switch tube Q1, the type is: low voltage and high current MOSFET, the specification is: withstand voltage 100V, instantaneous current reaches 300A; isolation drive components: high-speed optocoupler U1, gate driver chip U2, these two components form a suspended drive with isolation function, ensuring that the source of Q1 can be reliably switched without grounding; freewheeling diodes D2-D6, the type is Dongke Semiconductor synchronous rectification chip, 5 in parallel, which provide high-efficiency high-current operation to ensure that when Q1 is turned off, the inductor can keep the current flowing; the output filter adopts second-order filtering, which can achieve a smoother DC output current compared to the first-order filtering of the conventional BUCK circuit.

[0086] The working process of the DC current generator is as follows: PWM signal drive: Q1 is driven to turn on through U1 and U2; power supply: the power supply simultaneously supplies power to the load and charges the inductor L1 energy storage and capacitor C5-C12; dark process: when Q1 is turned off, since the inductor current cannot change suddenly, D2-D6 provides a freewheeling path, so that the inductor can discharge continuously and complete a working cycle. The components of the output path are inductor L2 and capacitor C13-C17, which form a second-order filter, which helps to further smooth the output current; output interface: I_OUT+ and I_OUT- terminals are connected to both ends of the high-voltage reactor under test. The current monitoring component uses a Hall current sensor U3 to collect the output current, remove the AC component through a second-order filter, and output it to IDC_ADC for conversion and measurement.

[0087] The current and voltage measurement circuit includes a DC voltage acquisition circuit; Figure 3As shown in the figure, the main function of the DC voltage acquisition circuit is to collect the voltage signal at both ends of the high-voltage reactor and process the signal to eliminate interference; its input source is the voltage signal at both ends of the reactor input from the JP7 port; since the voltage induced by the reactor is usually very high and weakly coupled, the induced voltage generated is usually regarded as a virtual voltage. Preliminary signal processing: In the initial stage of the input signal, a small resistance resistor and capacitor C31 are used for preliminary filtering to eliminate most of the interference signals. Multi-order filter: After the signal is initially processed, it is passed to the multi-order filter; the filter is composed of inductors L3-L5 and capacitors C28-C30 to further remove residual interference signals; high-frequency interference filtering: inductor L5 and capacitors C28, C27 are mainly used to filter high-frequency interference to ensure the purity of the signal. Isolation and amplification: the filtered signal is sent to the isolation operational amplifier U5 for isolation and amplification to improve the stability and availability of the signal. Signal output: the processed signal is finally output to VDC_ADC for conversion and further processing by the microcontroller unit MCU.

[0088] like Figure 4 As shown in the figure, the MCU control circuit uses the STM32F446 high-performance 32-bit microcontroller MCU as the core, which has hard floating point and digital signal processing unit DSP, and supports fast Fourier transform FFT algorithm. The microcontroller MCU outputs PWM signals through the PWM pin to drive the MOSFET switch to control the opening and closing of the current; the output current is controlled by adjusting the duty cycle of the PWM signal; the processed current and voltage signals are input to the MCU and converted through the analog-to-digital converter ADC; the fast Fourier transform algorithm is applied in the microcontroller MCU to perform digital filtering and separate the DC voltage and current signals; finally, the separated signals are used to calculate the DC resistance of the reactor coil.

[0089] The microcontroller MCU distinguishes the signal characteristics of different frequency bands through wavelet transform, wavelet packet transform, and Fourier transform, and identifies and classifies interference signals. The microcontroller MCU uses an adaptive filter to perform an adaptive filtering algorithm to dynamically adjust the filtering parameters, automatically identifying and removing induced electricity and noise signals from reactors, surrounding power lines, and other electrical equipment. The microcontroller MCU performs adaptive noise elimination on each signal channel, using the difference between the main signal and the reference signal to estimate and eliminate noise; by analyzing the time domain characteristics and spectral characteristics of the signal, it can dynamically remove irrelevant noise components. After the above algorithm processing, the DC voltage and current signals are filtered out separately to ensure that the measuring device correctly measures the DC resistance of the high-voltage reactor.

[0090] The processes of wavelet transform, wavelet packet transform and Fourier transform are as follows:

[0091] The microcontroller MCU analyzes the time-frequency characteristics of the signal by decomposing it into different frequency bands based on wavelet transform;

[0092] The calculation formula of wavelet transform is as follows:

[0093]

[0094] Where W(a,b) is the wavelet transform coefficient, which represents the projection value of the signal at scale a and position b; x(t) is the input signal; is the complex conjugate of the mother wavelet function; is the mother wavelet function; a is the scale parameter, which controls the frequency resolution; b is the time shift parameter, which controls the time position; t is the time variable;

[0095] The microcontroller MCU further decomposes the details based on the wavelet decomposition based on the wavelet packet transform to obtain higher frequency resolution;

[0096] The calculation formula of wavelet decomposition is as follows:

[0097]

[0098] Where W j,k (t) is the coefficient of the kth node in the jth layer; W j+1,2k (t) is the low-frequency component of the 2kth node in the j+1th layer; W j+1,2k+1 (t) is the high-frequency component of the 2k+1th node in the j+1th layer;

[0099] h(n) and g(n) are low-pass and high-pass filters; n is the discrete sample point index; t is the time variable;

[0100] The microcontroller MCU converts the signal from the time domain to the frequency domain through Fourier transform to analyze the frequency components;

[0101] The calculation formula of Fourier transform is as follows:

[0102]

[0103] In the formula, X(f) is the spectrum of the signal in the frequency domain; x(t) is the original signal; e -j2πft is a complex exponential function; dt is a small change in the integral variable t; f is the frequency; j is the imaginary unit.

[0104] The adaptive filtering algorithm process is as follows:

[0105] Adaptive filtering algorithms include LMS algorithm and RLS algorithm;

[0106] The LMS algorithm updates the filter weights using the minimum mean square error criterion. The calculation formula is as follows:

[0107] Output signal:

[0108]

[0109] error:

[0110] e(n)=d(n)-y(n)

[0111] Weight update:

[0112] w i (n+1)=w i (n)+2μe(n)x(n-1)

[0113] Where y(n) is the filter output; M is the filter order; w i (n) is the ith weight of the filter, the filter weight value updated at time n; x(ni) is the value of the input signal at time ni; e(n) is the error signal; d(n) is the desired signal; w i (n+1) is the i-th weight value at time n+1; μ is the step size factor, which controls the speed of weight adjustment; 2μe(n)x(n-1) is the amount of weight update;

[0114] The RLS algorithm updates the filter weights based on the recursive least squares criterion, and the calculation formula is as follows:

[0115] Gain vector:

[0116]

[0117] error:

[0118] e(n)=d(n)-w T (n-1)x(n)

[0119] Weight update:

[0120] w(n)=w(n-1)+K(n)e(n)

[0121] Inverse covariance matrix update:

[0122]

[0123] Where K(n) is the gain vector; P(n-1) is the inverse covariance matrix at time n-1; x(n) is the input signal vector; λ is the forget factor, which controls the update speed of the weight; x T (n) is the transpose of the input signal vector x(n); e(n) is the error signal; d(n) is the desired signal; w T(n-1) is the transpose of the weight vector w(n-1) at time n-1; w(n) is the weight vector; P(n) is the inverse covariance matrix; λ is the forget factor, which controls the update speed of the weight; P(n-1) is the inverse covariance matrix at time n-1;

[0124] The steps of adaptive filtering algorithm are as follows:

[0125] Step 1: The reference signal x(n) enters the adaptive filter to generate the estimated noise n(n);

[0126] Step 2, main signal x s (n) minus the estimated noise to obtain the pure signal y(n):

[0127] y(n)=x s (n)-n(n)

[0128] Step 3, update the filter parameters to minimize the error:

[0129] e(n)=x s (n)-y(n)

[0130] Adjust filter weights according to the LMS algorithm and the RLS algorithm.

[0131] In summary, the DC resistance measuring device of the high-voltage reactor adopts a DC current generator, a multi-order LC filter, a current and voltage measurement circuit, and an MCU control circuit in the measuring device part; when measuring the DC resistance of the reactor, the DC current generator generates a 0-20A DC current, which flows through the high-voltage reactor and generates a voltage drop at both ends of the high-voltage reactor. By measuring this voltage drop, the DC resistance of the reactor can be calculated. Since the above-mentioned interference will cause other strong interfering AC components to be mixed in the reactor winding, a low-resistance resistor is used for bypass in hardware, and a multi-order LC low-pass filter is added to filter out the AC component to the maximum extent. However, it is impossible for the hardware to completely filter out the AC component, and some residual AC components enter the voltage measurement circuit, so the microcontroller MCU uses filtering algorithms such as fast Fourier transform to separate the DC component to achieve the purpose of accurately detecting the DC resistance of the reactor.

[0132] In addition, in terms of indoor isolation, Figure 5As shown, the high-voltage reactor DC resistance measuring device includes a shielding device, which is a cover structure, including an internal insulation layer 4 arranged layer by layer from the outside to the inside; a high-conductivity metal layer 1, a middle insulation layer 2, a high-permeability magnetic shielding layer 3 and an internal insulation layer 4, which are detachably connected to the high-voltage reactor; the shielding device is covered on the measuring device and the high-voltage reactor, so that the measuring device and the high-voltage reactor are in a sealed state. Among them, the high-conductivity metal layer 1 is made of high-conductivity metal materials such as copper Cu or aluminum Al. The main function of this layer is to provide effective electric field shielding and reduce the influence of induced voltage on the measurement results. At the same time, it can guide the induced current and lead it to the ground through good conductivity, thereby protecting the safety of the test equipment and operators.

[0133] The middle insulating layer 2 is made of polymer materials (such as polyethylene, polyvinyl chloride, etc.) or ceramic materials and has good insulation properties. The function of this layer is to isolate the electrical connection between the high-conductivity metal layer 1 and the high-permeability magnetic shielding layer 3 to prevent short circuits, while providing a certain mechanical strength and stability to ensure the reliability of the shielding device in complex environments.

[0134] The high permeability magnetic shielding layer 3 is made of iron-nickel alloy (such as Mu-Metal) or other alloys, which can effectively shield the magnetic field. The main function of this layer is to shield external magnetic interference and reduce the influence of the variable magnetic field generated by the transformer or other equipment when working on the reactor measurement. This magnetic shielding helps to improve the accuracy and reliability of the measurement.

[0135] The material of the inner insulating layer 4 is similar to that of the middle insulating layer 2, usually a polymer insulating material or a ceramic material. This layer is used to protect the internal coil and other electrical components, prevent short circuits or leakage, and ensure the electrical safety of the entire shielding structure; at the same time, it can also reduce the generation and propagation of electrical noise, further improving the stability of the measurement results.

[0136] The four-layer structure of the high-conductivity metal layer 1, the middle insulating layer 2, the high-permeability magnetic shielding layer 3, and the internal insulating layer 4 can effectively reduce the interference of induced electric and magnetic fields during field operations, ensuring the safety and accuracy of the reactor in measuring DC resistance under high-voltage environments.

[0137] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high voltage reactor DC resistance measuring device integrated with a shielding device, characterized in that: The high-voltage reactor DC resistance measuring device comprises a shielding device and a measuring device; The measuring device comprises a DC current generator, a bypass resistor and a multi-order LC filter electrically connected to the high-voltage reactor, wherein the bypass resistor and the multi-order LC filter form a parallel relationship, a current and voltage measuring circuit electrically connected to the bypass resistor and the multi-order LC filter, and an MCU control circuit electrically connected to the current and voltage measuring circuit; The shielding device is a cover structure, including an internal insulation layer arranged layer by layer from the outside to the inside; a high-conductivity metal layer, a middle insulation layer, a high-permeability magnetic shielding layer and an internal insulation layer, which is detachably connected to the high-voltage reactor; the shielding device covers the measuring device and the high-voltage reactor, so that the measuring device and the high-voltage reactor are in a sealed state.

2. The high-voltage reactor DC resistance measuring device integrated with a shielding device according to claim 1, characterized in that: The high-voltage reactor DC resistance measuring device generates a specified DC current through a DC current generator and supplies it to the reactor; the reactor generates a voltage drop, and the bypass resistor bypasses the AC interference; The multi-order LC filter further filters the AC component and outputs a pure voltage signal; the current and voltage measurement circuit measures the voltage and current data of the reactor and sends it to the MCU control circuit; the MCU processes the data, extracts the effective DC component and calculates the DC resistance of the reactor.

3. The high voltage reactor DC resistance measuring device integrated with a shielding device according to claim 2, characterized in that: The DC current generator adopts a BUCK step-down constant current circuit to reduce the input voltage to a lower output voltage and stably provide a DC current of 0-20A; the DC current generator includes a main switch tube, an optocoupler and a gate driver, a freewheeling diode, a filter, and a current sensor.

4. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 3, characterized in that: The DC current generator drives the main switch tube to turn on through an optocoupler and a gate driver chip based on a PWM signal; when the main switch tube is driven to turn on, the power supply supplies power to the load, and the inductor stores energy and charges the capacitor at the same time; when the main switch tube is turned off, the inductor current cannot change suddenly, and the freewheeling diode provides a freewheeling path to complete a working cycle; the DC current generator further smoothes the output current through a second-order filtering combination of the filter, and supplies power to the inductor under test; the Hall current sensor collects the output current in real time and outputs it to the microcontroller MCU through the analog-to-digital converter ADC.

5. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 2, characterized in that: The current and voltage measurement circuit comprises a DC voltage acquisition circuit; the input signal of the DC voltage acquisition circuit is derived from the voltage signal at both ends of the high-voltage reactor, and the DC voltage acquisition circuit uses a small-value resistor and a capacitor for preliminary processing to eliminate most interference signals; the signal is further processed by a multi-stage filter composed of an inductor and a capacitor to remove residual high-frequency interference signals; the signal after filtering is sent to an isolation operational amplifier for signal isolation and amplification to isolate the interference between the subsequent circuit and the front-end circuit; finally, the amplified and isolated signal is output from the analog-to-digital converter ADC to the microcontroller MCU.

6. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 2, characterized in that: The MCU control circuit uses the STM32F446 high-performance 32-bit microcontroller MCU as the core, which has hard floating point and digital signal processing unit DSP and supports fast Fourier transform FFT algorithm; The microcontroller MCU outputs a PWM signal through the PWM pin to drive the MOSFET switch to control the on and off of the current; the output current is controlled by adjusting the duty cycle of the PWM signal; the processed current and voltage signals are input to the MCU and converted by the analog-to-digital converter ADC; The fast Fourier transform algorithm is applied in the microcontroller MCU to perform digital filtering to separate the DC voltage and current signals; finally, the DC resistance of the reactor coil is calculated using the separated signals.

7. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 6, characterized in that: The microcontroller MCU distinguishes the signal characteristics of different frequency bands through wavelet transform, wavelet packet transform and Fourier transform, and identifies and classifies interference signals; The microcontroller MCU uses an adaptive filter to perform an adaptive filtering algorithm to dynamically adjust filtering parameters, automatically identify and remove induced electricity and noise signals from reactors, surrounding power lines and other electrical equipment; The microcontroller MCU performs adaptive noise elimination on each signal channel, using the difference between the main signal and the reference signal to estimate and eliminate noise; by analyzing the time domain characteristics and spectral characteristics of the signal, it can dynamically remove irrelevant noise components; After the above algorithm processing, the DC voltage and current signals are filtered out separately, ensuring that the measuring device correctly measures the DC resistance of the high-voltage reactor.

8. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 7, characterized in that: The microcontroller MCU analyzes the time-frequency characteristics of the signal by decomposing the signal into different frequency bands based on wavelet transform; The calculation formula of wavelet transform is as follows: Where W(a,b) is the wavelet transform coefficient, which represents the projection value of the signal at scale a and position b; x(t) is the input signal; is the complex conjugate of the mother wavelet function; is the mother wavelet function; a is the scale parameter, which controls the frequency resolution; b is the time shift parameter, which controls the time position; t is the time variable; The microcontroller MCU further decomposes the detail part based on the wavelet decomposition based on the wavelet packet transform to obtain a higher frequency resolution; The calculation formula of wavelet decomposition is as follows: Where W j,k (t) is the coefficient of the kth node in the jth layer; W j+1,2k (t) is the low-frequency component of the 2kth node in the j+1th layer; W j+1,2k+1 (t) is the high-frequency component of the 2k+1th node in the j+1th layer; h(n) and g(n) are low-pass and high-pass filters; n is the discrete sample point index; t is the time variable; The microcontroller MCU converts the signal from the time domain to the frequency domain through Fourier transform to analyze the frequency components; The calculation formula of Fourier transform is as follows: In the formula, X(f) is the spectrum of the signal in the frequency domain; x(t) is the original signal; e -j2πft is a complex exponential function; dt is a small change in the integral variable t; f is the frequency; j is the imaginary unit.

9. The device for measuring the DC resistance of a high-voltage reactor integrated with a shielding device according to claim 7, characterized in that: The adaptive filtering algorithm includes an LMS algorithm and an RLS algorithm; The LMS algorithm updates the filter weights using the minimum mean square error criterion. The calculation formula is as follows: Output signal: error: e(n)=d(n)-y(n) Weight update: w i (n+1)=w i (n)+2μe(n)x(n-1) Where y(n) is the filter output; M is the filter order; w i (n) is the ith weight of the filter, the filter weight value updated at time n; x(ni) is the value of the input signal at time ni; e(n) is the error signal; d(n) is the desired signal; w i (n+1) is the i-th weight value at time n+1; μ is the step size factor, which controls the speed of weight adjustment; 2μe(n)x(n-1) is the amount of weight update; The RLS algorithm updates the filter weights based on the recursive least squares criterion, and the calculation formula is as follows: Gain vector: error: e(n)=d(n)-w T (n-1)x(n) Weight update: w(n)=w(n-1)+K(n)e(n) Inverse covariance matrix update: Where K(n) is the gain vector; P(n-1) is the inverse covariance matrix at time n-1; x(n) is the input signal vector; λ is the forget factor, which controls the update speed of the weight; x T (n) is the transpose of the input signal vector x(n); e(n) is the error signal; d(n) is the desired signal; w T (n-1) is the transpose of the weight vector w(n-1) at time n-1; w(n) is the weight vector; P(n) is the inverse covariance matrix; λ is the forget factor, which controls the update speed of the weight; P(n-1) is the inverse covariance matrix at time n-1; The steps of the adaptive filtering algorithm are as follows: Step 1: The reference signal x(n) enters the adaptive filter to generate the estimated noise n(n); Step 2, main signal x s (n) minus the estimated noise to obtain the pure signal y(n): y(n)=x s (n)-n(n) Step 3, update the filter parameters to minimize the error: e(n)=x s (n)-y(n) Adjust filter weights according to the LMS algorithm and the RLS algorithm.

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