Pulse Injection Method for Dual-Parameter Detection and Estimation of Residual Current and Insulation Resistance

Abstract

This invention relates to the field of multi-branch floating ground power supply technology, and discloses a pulse-injection method for dual-parameter detection and estimation of residual current and insulation resistance. The method includes: injecting a symmetrical positive and negative pulse with zero net charge between the power supply midpoint and the grounding terminal; simultaneously acquiring the differential current and midpoint voltage of each branch; symmetrically decomposing the pulses to separate the steady-state leakage current component and the transient return current component; using the time integral of the total return current component to invert the capacitance time constant, insulation time constant, and capacitance weight; then extracting the insulation charge to obtain the global insulation resistance; using the insulation time constant to weight the transient return current component of each branch to obtain the branch leakage current ratio, mapping the output branch insulation resistance and residual current; finally, continuously fusing steady-state and transient data by generating dynamic coefficients, and adaptively updating the injection duration for the next round. This invention eliminates ring network shunt interference and achieves accurate positioning and anti-interference assessment of the dual parameters.

Description

Technical Field

[0001] This invention relates to the field of multi-branch floating ground power supply technology, and more specifically, to a pulse injection method for detecting and estimating two parameters: residual current and insulation resistance. Background Technology

[0002] In applications such as intelligent substation ring network DC systems, multi-branch HVDC distribution networks for communication base stations, and medical isolation distribution systems, multi-branch floating ground operation is commonly used to ensure the continuity and high reliability of power supply. In these scenarios, insulation monitoring and leakage current protection are crucial for maintaining safe system operation. Currently, low-frequency pulse injection is typically used to assess the insulation performance of the system and its individual branches. However, in ring network multi-branch systems, the significant and unevenly distributed capacitance to ground caused by long cables and the parallel paths created by the closed ring network mean that the injected pulse current not only flows through faulty branches with deteriorated insulation but also experiences significant shunting and backflow in the distributed capacitance of healthy branches and the ring network loop. This complex charge flow path means that the differential current measured by transformers using conventional monitoring methods no longer monotonically corresponds to the actual insulation degradation level of that branch, resulting in a spatial mismatch between the monitored residual current parameters and the actual insulation resistance parameters. If the deviation caused by ring network shunting and capacitor backfeed is not effectively isolated and quantified, transient shunting crosstalk is easily misjudged as a decrease in insulation resistance, thus triggering frequent false alarms. This causes serious confusion in traditional dual-parameter detection, restricting the safe operation and maintenance efficiency and monitoring accuracy of multi-branch floating ground power supply networks. Summary of the Invention

[0003] This invention provides a pulse injection method for detecting and estimating two parameters: residual current and insulation resistance, which solves the technical problems mentioned in the background art.

[0004] This invention provides a pulse-injection method for dual-parameter detection and estimation of residual current and insulation resistance, including:

[0005] Positive and negative symmetrical pulses are injected between the power supply midpoint and the grounding terminal, and the differential current, midpoint voltage and bus voltage of each branch are collected simultaneously.

[0006] The differential current and the midpoint voltage are symmetrically decomposed to separate the steady-state leakage current component and the transient return current component, and the total leakage current corresponding to the steady-state leakage current component is obtained.

[0007] The time integral of the total return current component generated by superimposing the transient return current components of each branch is calculated to obtain the capacitance time constant, insulation time constant and capacitance weight.

[0008] Based on the capacitance weight, the insulation charge is extracted, and the transient return current component of the midpoint voltage is weighted using the insulation time constant to obtain the reference voltage, and the global insulation resistance is calculated.

[0009] The transient return current component of each branch is weighted using the insulation time constant to obtain the branch leakage current ratio. Combined with the global insulation resistance and the bus voltage, the branch insulation resistance and branch residual current are output.

[0010] The total return current component is reconstructed using the capacitance time constant and the insulation time constant to generate a dynamic coefficient. The total leakage current and the global insulation resistance are then fused using the dynamic coefficient, and the sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round.

[0011] The beneficial effects of this invention are as follows: By injecting positive and negative symmetrical pulses at the power supply midpoint and grounding terminal and performing symmetrical decomposition, the steady-state leakage current component and transient return current component are successfully separated. Then, by using the time integration of the transient return current component to invert multi-mode parameters, the problem of parameter spatial mismatch caused by ring network current shunting and distributed capacitor backfeed is effectively overcome. This invention realizes accurate quantification of the global and branch insulation status and lossless mapping of residual current. It not only avoids the risk of misjudgment caused by capacitor charging and discharging interference in multi-branch floating ground networks, but also greatly improves the long-term stability and adaptive evolution capability of system-level leakage current monitoring through the generation and dynamic fusion of continuous confidence coefficients. Attached Figure Description

[0012] Figure 1 This is a flowchart of the pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance of the present invention. Detailed Implementation

[0013] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0014] like Figure 1 As shown, a pulse injection method for detecting and estimating residual current and insulation resistance as dual parameters includes:

[0015] Positive and negative symmetrical pulses are injected between the power supply midpoint and the grounding terminal, and the differential current, midpoint voltage and bus voltage of each branch are collected simultaneously.

[0016] The differential current and the midpoint voltage are symmetrically decomposed to separate the steady-state leakage current component and the transient return current component, and the total leakage current corresponding to the steady-state leakage current component is obtained.

[0017] The time integral of the total return current component generated by superimposing the transient return current components of each branch is calculated to obtain the capacitance time constant, insulation time constant and capacitance weight.

[0018] Based on the capacitance weight, the insulation charge is extracted, and the transient return current component of the midpoint voltage is weighted using the insulation time constant to obtain the reference voltage, and the global insulation resistance is calculated.

[0019] The transient return current component of each branch is weighted using the insulation time constant to obtain the branch leakage current ratio. Combined with the global insulation resistance and the bus voltage, the branch insulation resistance and branch residual current are output.

[0020] The total return current component is reconstructed using the capacitance time constant and the insulation time constant to generate a dynamic coefficient. The total leakage current and the global insulation resistance are then fused using the dynamic coefficient, and the sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round.

[0021] Preferably, positive and negative symmetrical pulses are injected between the power supply midpoint and the grounding terminal to synchronously collect the differential current, midpoint voltage, and bus voltage of each branch, including:

[0022] The power supply midpoint is obtained. When the power supply system has a physical midpoint, the physical midpoint is used as the power supply midpoint. When the power supply system does not have the physical midpoint, two resistors with equal resistance are connected in series between the positive bus and the negative bus. The connection point of the two resistors is used as the composite midpoint, and the composite midpoint is used as the power supply midpoint.

[0023] The positive and negative symmetrical pulses are constructed according to the following calculation formula:

[0024]

[0025] in, Let be the waveform function of the positive and negative symmetrical pulses as a function of time. For single half-pulse amplitude, It is a single half-pulse width. For unit step function, It is a time variable;

[0026] The positive and negative symmetrical pulses are applied between the power supply midpoint and the grounding terminal, and the differential current, midpoint voltage and bus voltage of each branch are synchronously collected at a preset sampling frequency.

[0027] The power supply midpoint is the reference position where the positive and negative symmetrical pulses enter the power supply system, and is used to apply the injected excitation evenly to the ground channels corresponding to the positive and negative buses.

[0028] The physical midpoint is the actual intermediate potential point that already exists within the power supply system itself.

[0029] The synthesized midpoint is an intermediate potential point artificially established through the connection point of the two resistors when the power supply system itself does not have a physical midpoint.

[0030] The positive busbar is the main conductor in the power supply system that carries the positive potential.

[0031] The negative busbar is the main conductor in the power supply system that carries the negative potential.

[0032] A positive-negative symmetrical pulse is an injection signal consisting of two consecutive half-pulses with opposite polarities and equal amplitudes, used to excite the ground insulation response without forming a net DC bias.

[0033] The first half-pulse is the first half of the positive and negative symmetrical pulse excitation, used to establish an injection response in the first direction within the first time window.

[0034] The second half-pulse is the latter half of the positive-negative symmetrical pulse, used to establish an injection response in the opposite direction to the first half-pulse within the second time window.

[0035] The waveform function of the positive and negative symmetrical pulses changing with time is a functional representation of the positive and negative symmetrical pulses throughout the entire injection period.

[0036] The amplitude of a single half-pulse is the excitation intensity of each half-pulse relative to the zero baseline. It is preferably 1 to 3 / 100 of the rated voltage to ground of the bus; when the signal is weak, it can be increased to within 5 / 100; because it is necessary to ensure that the differential current and the midpoint voltage have sufficient resolution, while avoiding significant disturbance to the original power supply state.

[0037] The single half-pulse width is the duration of a single half-pulse, used to determine the completeness of the observation of transient return current to ground and steady-state leakage current processes within a time window. It is preferably between five and twenty milliseconds and must be configured as an integer multiple of the power frequency interference period. After the first round of estimation, it is the sum of the capacitance time constant and the insulation time constant; this is because it needs to cover fast response while also using periodic symmetry to cancel AC crosstalk and avoid introducing additional slow changes due to an excessively long time window.

[0038] The unit step function is a piecewise function used to describe the transition of a waveform from a closed state to an open state at a switching moment, and is used to construct the boundary between the first half-pulse and the second half-pulse.

[0039] The time variable is a quantity used to mark the position of waveforms, differential currents, and midpoint voltages at various times.

[0040] The preset sampling frequency is the sampling speed when synchronously acquiring the differential current, the midpoint voltage, and the bus voltage. Preferably, one half-pulse width contains 100 to 500 sampling points; when the half-pulse width is 5 milliseconds to 20 milliseconds, it is preferably 10 kHz to 100 kHz; thereby ensuring time alignment accuracy and integration accuracy.

[0041] Differential current is the net unbalanced current formed by each branch relative to the ground loop during the injection process, used to characterize the return current participation of the branch in the injected excitation. It can be obtained by synchronously acquiring the net unbalanced current of each branch conductor.

[0042] The midpoint voltage is the potential difference between the power supply midpoint and the grounding terminal, used to reflect the global ground response. It can be obtained by synchronously acquiring the potential difference between the power supply midpoint and the grounding terminal.

[0043] Bus voltage is the potential difference between the positive bus and the negative bus, used to reflect the main power supply voltage level of the system. It can be obtained by synchronously acquiring the potential difference between the positive bus and the negative bus.

[0044] In detail, because the power supply midpoint is located at the potential center between the positive and negative busbars, when the positive and negative symmetrical pulses are applied between the power supply midpoint and the grounding terminal, the grounding channels corresponding to the positive and negative busbars can be excited simultaneously.

[0045] In detail, since not all power supply systems have a physical midpoint, when the system lacks a natural midpoint, two resistors with equal resistance values ​​need to be connected in series between the positive and negative busbars, and the connection point is taken as the synthetic midpoint, so as to establish a stable injection reference point without changing the main power supply structure.

[0046] In detail, because the first half-pulse and the second half-pulse have equal amplitudes, opposite polarities, and the same width, the total injected charge of the two half-pulses cancels each other out, thus avoiding the formation of a continuous DC bias.

[0047] In detail, because it is necessary to compare the changes of the differential current and the midpoint voltage of each branch in two half-pulses at the same time, the differential current, the midpoint voltage and the bus voltage of each branch must be acquired synchronously.

[0048] In detail, the resistance values ​​of the two resistors are selected as follows: the two resistors are selected to have the same resistance value and a large resistance value. The single resistor is preferably 1 megohm to 20 megohms, so that the combined midpoint is stable and the original leakage to ground of the power supply system is not significantly changed.

[0049] In detail, the method of applying the positive and negative symmetrical pulses between the power supply midpoint and the grounding terminal is as follows: first output the first half pulse, then continuously output the second half pulse, without setting a gap time between the two half pulses, when the polarity of the first half pulse is positive, the polarity of the second half pulse is negative, and vice versa, and the switching time of the two half pulses is aligned with the start time of synchronous acquisition.

[0050] In detail, the selection method for the single-half pulse amplitude and the single-half pulse width is as follows: the single-half pulse amplitude is selected according to 1 / 100 to 5 / 100 of the rated ground level corresponding to the bus voltage, and the single-half pulse width is selected according to 5 milliseconds to 20 milliseconds; after the capacitance time constant and the insulation time constant are obtained in the first round of calculation, the single-half pulse width is updated to the sum of the two.

[0051] In detail, the method of matching the preset sampling frequency with the single and half pulse width is as follows: ensure that there are at least 100 effective sampling points within one single and half pulse width, so that the time of delaying one single and half pulse width can be accurately located in the sampling sequence;

[0052] In detail, the method of triggering and aligning the synchronous acquisition is as follows: taking the start time of the first half pulse as the zero time, the differential current, the midpoint voltage and the bus voltage of each branch are acquired using the same triggering start point, so that the same sampling sequence number corresponds to the same time.

[0053] Preferably, the differential current and the midpoint voltage are symmetrically decomposed to separate the steady-state leakage current component and the transient return current component, including:

[0054] Fold the time window corresponding to the second half-pulse back to the time window corresponding to the first half-pulse, and obtain the transient return current component and the steady-state leakage current component corresponding to the differential current according to the following calculation formula:

[0055]

[0056]

[0057] The transient return current component and the steady-state leakage current component corresponding to the midpoint voltage are obtained using the following calculation formulas:

[0058]

[0059]

[0060] The total leakage current corresponding to the steady-state leakage current component is generated using the following formula:

[0061]

[0062] in, It is a time variable, and its value ranges between zero and the width of the single half-pulse; The width of the single half-pulse; Branch number; The total number of branch roads; For the first The branch road at the current moment The differential current; For the first The differential current of the branch at a time delayed by one half-pulse width; For the first The transient return current component corresponding to the differential current of the branch; For the first The steady-state leakage current component corresponding to the differential current of the branch; For the current moment The midpoint voltage; The midpoint voltage is a time delay of one half-pulse width; The transient return current component corresponding to the midpoint voltage; The steady-state leakage current component corresponding to the midpoint voltage; The total leakage current corresponding to the steady-state leakage component; The symbol for absolute value calculation; For summation calculation symbols; This is the symbol for time integration calculation.

[0063] The differential current at the current moment is the value of the differential current of a certain branch at the current sampling moment. It can be obtained by reading the value at the current sampling position from the synchronously acquired differential current sequence.

[0064] The differential current delayed by one half-pulse width is the differential current value of the same branch at a time corresponding to a segment of one half-pulse width after the current time. It can be obtained by reading from the synchronously acquired differential current sequence with a fixed sampling offset corresponding to one half-pulse width.

[0065] The transient backflow component corresponding to the differential current is the part of the differential current that changes in the opposite direction as the polarity of the first half-pulse and the second half-pulse reverses, and is used to characterize the transient backflow caused by the injection.

[0066] The steady-state leakage current component corresponding to the differential current is the part of the differential current that changes in the same direction and in the same manner at the corresponding moments of the two half-pulses, and is used to characterize the relatively stable leakage current level.

[0067] The midpoint voltage at the current moment is the value of the midpoint voltage at the current sampling moment. It can be obtained by reading the value at the current sampling position from the synchronously acquired midpoint voltage sequence.

[0068] The midpoint voltage at a time delayed by one half-pulse width is the midpoint voltage value at a time corresponding to a segment of one half-pulse width after the current time. It can be obtained by reading from the synchronously acquired midpoint voltage sequence with a fixed sampling offset corresponding to one half-pulse width.

[0069] The transient return current component corresponding to the midpoint voltage is the part of the midpoint voltage that changes in opposite directions as the polarity of the two half-pulses reverses, and is used to reflect the global transient return current voltage response to ground.

[0070] The steady-state leakage current component corresponding to the midpoint voltage is the part of the midpoint voltage that maintains a common trend at the corresponding moments of the two half-pulses, and is used to reflect the globally relatively stable leakage current voltage response.

[0071] Branch number is a number used to distinguish different branches.

[0072] The total number of branches is the number of branches included in the calculation of the power supply system.

[0073] Total leakage current is the overall leakage current obtained by summing the steady-state leakage current components of all branches at the same time, and is used to characterize the global steady-state leakage current level.

[0074] In detail, because the first half-pulse and the second half-pulse are equal in excitation amplitude but opposite in polarity, after folding the time window corresponding to the second half-pulse back to the time window corresponding to the first half-pulse, the two sets of samples at the same moment can be directly used for sum and difference calculations.

[0075] In detail, because the transient return current component changes in the opposite direction as the pulse polarity reverses, the difference between the differential current at the current moment and the differential current at a moment delayed by one half-pulse width, and then taking half of the difference, can separate this polarity-reversed portion from the mixed signal.

[0076] In detail, because the steady-state leakage current component does not depend on the polarity reversal between the two half-pulses, the steady portion can be retained by summing the differential current at the current moment with the differential current at a moment delayed by one half-pulse width and taking half of the sum.

[0077] In detail, because the midpoint voltage, like the differential current, contains both transient return current and steady-state leakage current, the midpoint voltage must be decomposed in the same way as the differential current.

[0078] In detail, since the steady-state leakage current components of each branch together constitute the total leakage current at the system level, it is necessary to first sum the steady-state leakage current components of each branch at the same moment, then take the absolute value and perform time integration and average value calculation within a single half-pulse width to obtain the global steady-state leakage current level.

[0079] In detail, the positioning method for delaying the moment by one half-pulse width is as follows: In the sampling sequence, the number of sampling points corresponding to the half-pulse width is used as a fixed offset. Sampling points at the same offset are read forward from the current sampling point. When the half-pulse width is not divisible by the sampling interval, the value at that moment is calculated according to the proportional relationship between adjacent sampling points.

[0080] In detail, the method of folding the time window corresponding to the second half-pulse back to the time window corresponding to the first half-pulse is as follows: taking the start time of the first half-pulse as the zero time, remapping the sampled values ​​in the second half-pulse that are separated from the current time by one half-pulse width to the same time of the first half-pulse, and then performing sum and difference operations.

[0081] In detail, the processing method when the differential current or the midpoint voltage changes slowly is as follows: first, complete the one-to-one correspondence between the current time and the time delayed by one half-pulse width, and then perform decomposition, integration and average value calculation only within the time window corresponding to one half-pulse width, so as to reduce the impact of slow changes on the decomposition results.

[0082] In detail, the time integral and average value are calculated as follows: the integrand is accumulated point by point at all sampling moments corresponding to the single half-pulse width, and after the accumulation is completed, it is divided by the length of the time window to obtain the corresponding time average value.

[0083] Preferably, the time integral of the total return current component superimposed from the transient return current components of each branch is calculated to obtain the capacitance time constant, insulation time constant, and capacitance weight, including:

[0084] The transient return current components of the differential currents of each branch at the same time are summed to generate the total return current component, and the normalized return current density is generated according to the following formula:

[0085]

[0086]

[0087]

[0088] The first-order time integral, the second-order time integral, and the third-order time integral are obtained using the following formulas:

[0089]

[0090]

[0091]

[0092] The first and second intermediate values ​​are obtained using the following formula:

[0093]

[0094]

[0095]

[0096] The capacitance time constant, the insulation time constant, and the capacitance weight are obtained using the following formulas:

[0097]

[0098]

[0099]

[0100] in, The total reflux component, The total number of branch roads, Branch number, For the first The transient return current component corresponding to the differential current of the branch. To align the total return flow component with the sign, For symbolic functions, and For time variables, The width of the single half-pulse, The normalized reflux density, This is the first-order time integral. This is the second-order time integral. For the third-order time integral, To assist in calculating variables, This is the first intermediate quantity. This is the second intermediate quantity. The capacitor time constant is... The insulation time constant is... The capacitor weight is denoted as .

[0101] The total return flow component is the global transient return flow formed by summing the transient return flow components of all branches at the same moment, and is used to characterize the overall return flow process of the system.

[0102] The sign-aligned total return component is a return flow that is uniformly adjusted to the same sign direction after the total return component is judged as a whole, in order to eliminate the difference in reference polarity.

[0103] Normalized reflux density is a time distribution obtained by normalizing the total reflux component with sign alignment according to the total amount within one half-pulse width. It is used to highlight the time shape while weakening the influence of the total amount size.

[0104] The time variable is the integration time quantity used in time integration, which is used to mark the distribution position of the integrand within one half-pulse width.

[0105] The first-order time integral is a quantity obtained by integrating the normalized reflux density with time weighting once, and is used to characterize the average time position of the reflux process.

[0106] The second-order time integral is a quantity obtained by integrating the normalized reflux density with a second-order time weight, and is used to characterize the extent of the reflux process relative to the time position.

[0107] The third-order time integral is a quantity obtained by integrating the normalized reflux density with three time weights, which is used to enhance the sensitivity to changes in the time tail.

[0108] The first auxiliary calculation variable is an auxiliary quantity obtained directly from the first-order time integral.

[0109] The second auxiliary calculation variable is an auxiliary quantity obtained by converting the second-order time integral.

[0110] The third auxiliary calculation variable is an auxiliary quantity obtained by converting the third-order time integral.

[0111] The first intermediate quantity is the intermediate result before root finding formed by combining three auxiliary calculation variables.

[0112] The second intermediate quantity is another intermediate result before root finding, formed by combining three auxiliary calculation variables.

[0113] The capacitance time constant is the time scale corresponding to the faster-changing part of the total return current component, and is used to describe the decay rate of the capacitance-related return current process.

[0114] The insulation time constant is the time scale corresponding to the slower-changing part of the total return current component, and is used to describe the decay rate of insulation-related processes.

[0115] The capacitance weight is the relative proportion of the capacitance-related part in the total return current component, used to further decompose the total return current charge into capacitance-related and insulation-related parts.

[0116] In detail, since the transient return current components of each branch are all excited by the same positive and negative symmetrical pulse, the total return current component formed by summing the transient return current components of each branch at the same moment can represent the global transient return current process of the entire power supply system.

[0117] In detail, because the positive and negative directions of the total return current component are affected by the acquisition reference direction, the total return current component is first integrated over time to determine its sign, and then it is uniformly adjusted to the same sign direction, so that it can reflect only the time process without being disturbed by the reference direction.

[0118] In detail, because the symbol-aligned total return component includes both the total amount and the time distribution, after normalizing it to the normalized return density, the first-order time integral, the second-order time integral, and the third-order time integral mainly reflect the time pattern and no longer mainly reflect the total charge size.

[0119] In detail, because a total return current component contains both a fast-changing part related to the capacitance time constant and a slow-changing part related to the insulation time constant, it is necessary to use the first-order time integral, the second-order time integral, and the third-order time integral to establish a solution relationship in order to identify these two different time scales simultaneously.

[0120] In detail, since the faster-changing part corresponds to a smaller time scale and the slower-changing part corresponds to a larger time scale, the smaller time root obtained by adding or subtracting the square root of the difference between the first intermediate quantity and four times the second intermediate quantity is defined as the capacitance time constant, and the larger time root obtained is defined as the insulation time constant.

[0121] In detail, since the first-order time integral reflects the overall time position, while the capacitance time constant and the insulation time constant represent the time scales of the fast-changing and slow-changing parts respectively, the capacitance weight can be obtained by normalizing the difference between the insulation time constant and the first-order time integral according to the difference between the two types of time constants.

[0122] In detail, the method for aligning the integral sign and symbol of the total return current component is as follows: first, perform time integration on the total return current component within one half-pulse width, and use the positive or negative sign of the integration result as the overall sign, and then uniformly adjust the total return current component to the same direction as the overall sign.

[0123] In detail, the normalization process for the symbol-aligned total return current component is as follows: using the time integral of the symbol-aligned total return current component within one half-pulse width as the normalization benchmark, the symbol-aligned total return current component at each moment is divided by the normalization benchmark, and before the higher-order multiplication and addition operations, the tail values ​​below the white noise lower limit of the sampling device are forcibly reset to zero. When the normalization benchmark becomes too small, the current round of calculation is stopped and the next round of injection duration is reset.

[0124] In detail, the time root selection method for solving the quadratic equation based on the first and second intermediate quantities is as follows: real roots greater than 0 are preferentially retained, and the smaller time root is used as the capacitance time constant, while the larger time root is used as the insulation time constant. When no two real roots greater than 0 exist, the current round of calculation is stopped and the injection duration for the next round is reset.

[0125] In detail, the applicable method for obtaining the capacitance time constant and the insulation time constant simultaneously from the same total return current component is as follows: the total return current component should exhibit a continuous decay process that is fast at first and slow at the end within one half-pulse width, and the first-order time integral, the second-order time integral, and the third-order time integral should maintain a consistent progressive relationship.

[0126] In detail, the denominator protection method when calculating the capacitor weight is as follows: when the difference between the insulation time constant and the capacitor time constant is too small, the capacitor weight is not directly output, but the single half pulse width is reset and recalculated.

[0127] Preferably, the insulation charge is extracted based on the capacitance weight, and the transient return current component of the midpoint voltage is weighted using the insulation time constant to obtain a reference voltage. The global insulation resistance is then calculated, including:

[0128] The total return charge and the insulating charge are calculated using the following formula:

[0129]

[0130]

[0131] The transient return current component of the midpoint voltage is processed according to the following calculation formula to generate the sign-aligned transient return current component corresponding to the midpoint voltage:

[0132]

[0133] The reference voltage is obtained by weighting the sign-aligned transient return current component corresponding to the midpoint voltage using the insulation time constant according to the following formula:

[0134]

[0135] The global insulation equivalent capacitance is obtained using the following formula, and the global insulation resistance is then calculated:

[0136]

[0137]

[0138] in, and For time variables, The width of the single half-pulse, Align the total return flow component with the symbols. The total reflux charge, The capacitor weight is... For the insulating charge, The transient return current component of the midpoint voltage. For symbolic functions, The sign-aligned transient return current component corresponds to the midpoint voltage. The insulation time constant is... It is a natural constant. The reference voltage is... This refers to the global insulation equivalent capacitance. The global insulation resistance is... This is the symbol for time integration calculation.

[0139] The value is a fixed constant, used to form a complementary relationship with the capacitor weight, and also to ensure that the insulating charge corresponds to the non-capacitive part.

[0140] The total return charge is the total charge obtained by integrating the sign-aligned total return component over a single half-pulse width, and is used to characterize the total amount carried by all transient return flows within that time window.

[0141] Insulation charge is the amount of insulation-related charge remaining after the capacitor-related portion is stripped from the total return charge according to the capacitor weight, and is used to characterize the effective charge carried by the insulation-related process.

[0142] The sign-aligned transient return current component corresponding to the midpoint voltage is a voltage process quantity obtained by making an overall determination of the transient return current component corresponding to the midpoint voltage and unifying the sign direction. It is used for weighted matching with the attenuation process corresponding to the insulation time constant.

[0143] The exponential decay factor is a weighting function that decreases over time according to the insulation time constant, used to give a more appropriate weight to the slower processes associated with insulation in the calculation of the reference voltage.

[0144] The first weighted integral is the quantity obtained by multiplying the sign-aligned transient backflow component corresponding to the midpoint voltage with the exponential decay coefficient at each time step and integrating it within one half-pulse width. It is used to accumulate the voltage contribution related to insulation.

[0145] The second weighted integral is the integral of the exponential decay coefficient itself within one half-pulse width, and is used to normalize the first weighted integral.

[0146] The reference voltage is a representative voltage obtained by dividing the first weighted integral by the second weighted integral, and is used together with the insulating charge to calculate the global insulation equivalent capacitance.

[0147] The global insulation equivalent capacitance is a system-level equivalent capacitance obtained from the relationship between the insulation charge and the reference voltage, used to connect the insulation time constant and the global insulation resistance.

[0148] The global insulation resistance is a system-level equivalent insulation resistance value determined by the insulation time constant and the global insulation equivalent capacitance, and is used to characterize the global insulation level of the entire power supply system.

[0149] The natural constant is a fixed constant that constitutes the natural exponential decay relationship and is used to describe the continuous decay process that matches the insulation time constant.

[0150] In detail, since the total return charge includes both capacitance-related and insulation-related components, it is necessary to first use the capacitance weight to subtract the capacitance-related component, and then define the remaining component as the insulation charge. This way, the result obtained from the insulation charge will not be contaminated by the capacitance-related process.

[0151] In detail, because the transient return current component corresponding to the midpoint voltage is also affected by the reference polarity direction, it is necessary to first align the integration sign and determination. Only in this way can the first weighted integral and the second weighted integral have the same directional significance.

[0152] In detail, since the insulation time constant corresponds to a relatively slow insulation-related decay process, after constructing the exponential decay coefficient according to this time scale, the sign-aligned transient return current component corresponding to the midpoint voltage is weighted to highlight the voltage part related to insulation, thereby forming a more stable reference voltage.

[0153] In detail, because a charge-voltage correspondence is formed between the insulating charge and the reference voltage, their ratio can give the global insulation equivalent capacitance. Furthermore, because the insulation time constant and the global insulation equivalent capacitance together correspond to a system-level insulation process, their ratio can give the global insulation resistance.

[0154] In detail, the method for determining the correspondence between the insulating charge, the capacitor weight, and the total return charge is as follows: first, the total return charge is considered to be formed by the part corresponding to the capacitor time constant and the part corresponding to the insulating time constant, and then the proportion after subtracting the capacitor weight from the value is allocated to the insulating charge.

[0155] In detail, the reference voltage is obtained as follows: first, the sign-aligned transient backflow component corresponding to the midpoint voltage is multiplied by the exponential decay coefficient at each time step, then time integration is completed within one half-pulse width, and the time integration of the exponential decay coefficient itself within the same time window is normalized to obtain the reference voltage.

[0156] In detail, the applicable method for obtaining the global insulation equivalent capacitance by dividing the insulation charge by the reference voltage is as follows: the reference voltage should maintain the same directional relationship with the insulation charge and not be close to 0, so that the global insulation equivalent capacitance remains positive and stable.

[0157] In detail, when the reference voltage is close to 0, the calculation and protection method for the global insulation equivalent capacitance and the global insulation resistance is as follows: stop outputting the global insulation equivalent capacitance and the global insulation resistance in this round, and recalculate after resetting the injection duration of the next round.

[0158] Preferably, the transient return current component of each branch is weighted using the insulation time constant to obtain the branch leakage current ratio, and combined with the global insulation resistance and the bus voltage, the branch insulation resistance and residual current are output, including:

[0159] The transient return current components corresponding to the differential current of each branch are sign-aligned according to the following calculation formula to generate the sign-aligned transient return current components for each branch:

[0160]

[0161] The leakage current percentage of each branch is calculated using the following formula:

[0162]

[0163] The effective ground stress and the globally estimated residual current are obtained using the following formulas:

[0164]

[0165]

[0166] Output the residual current and insulation resistance of each branch according to the following calculation formula:

[0167]

[0168]

[0169] in, Branch number, and For time variables, The width of the single half-pulse, For the first The transient return current component corresponding to the differential current of the branch. For symbolic functions, For the first The sign-aligned transient backflow components corresponding to each branch. The insulation time constant is... It is a natural constant. For the first The percentage of leakage current in the corresponding branch circuit. The total number of branch roads, To sum the branch numbers, This refers to the positive bus voltage to ground corresponding to the bus voltage. This refers to the negative bus voltage to ground corresponding to the bus voltage. The symbol for absolute value calculation. The effective ground stress, The global insulation resistance is... For the global estimate of the residual current, For the first The residual current of the corresponding branch. For the first The insulation resistance of the branch corresponding to each branch. The symbol for time integration is used. The symbol for summation calculation.

[0170] The sign-aligned transient return current component corresponding to each branch is a branch-level transient quantity obtained by making an overall sign and unifying the direction of the transient return current component of each branch. It is used to compare the contribution of each branch to the insulation-related return current.

[0171] The branch weighted integral is a quantity obtained by multiplying the sign-aligned transient return component corresponding to each branch by the exponential decay coefficient and integrating it over a single half-pulse width. It is used to characterize the degree of participation of the branch in the insulation-related process.

[0172] The branch leakage rate is the normalized proportion of the weighted integral of a certain branch relative to the sum of the weighted integrals of all branches, used to characterize the relative contribution of that branch to the global leakage process.

[0173] The summation branch number is a number used to perform summation traversal on all branches.

[0174] The voltage between the positive busbar and ground is the potential difference between the positive busbar and ground, used to characterize the voltage stress borne by the insulation of the positive side to ground.

[0175] The voltage between the negative busbar and ground is the potential difference between the negative busbar and ground, used to characterize the voltage stress borne by the insulation of the negative side to ground.

[0176] Effective ground stress is a system-level ground voltage characterization quantity obtained by averaging the absolute values ​​of the positive bus voltage to ground and the negative bus voltage to ground, and is used to correlate the bipolar ground stress.

[0177] The globally estimated residual current is the system-level residual current estimated from the relationship between the effective ground stress and the global insulation resistance.

[0178] The branch residual current is the branch-level estimated leakage current obtained by distributing the globally estimated residual current to each branch according to the leakage current ratio of the branch.

[0179] The branch insulation resistance is the branch-level equivalent insulation resistance value obtained by converting the global insulation resistance to the leakage current ratio of each branch.

[0180] In detail, because the transient return components of each branch may still present different signs due to different acquisition reference directions, it is necessary to perform sign alignment separately. Only in this way can the magnitude comparison between each branch be comparable.

[0181] In detail, since the insulation time constant represents the time scale of the insulation-related process, after aligning the signs of the transient return current components corresponding to each branch and performing weighted integration according to this time scale, the insulation-related parts can be highlighted more, thereby forming the branch weighted integral that better represents the degree of insulation participation.

[0182] In detail, since the degree of insulation participation of different branches should be compared in relative proportion rather than just in absolute size, the branch weighted integral of each branch is divided by the sum of the weighted integrals of all branches to obtain the leakage current ratio of the branch that can be directly compared.

[0183] In detail, since the insulation of the bipolar system simultaneously bears the voltage to ground of both the positive bus and the negative bus, taking the absolute values ​​of both and then averaging them can uniformly represent the bipolar voltage stress to ground as the effective stress to ground.

[0184] In detail, since the global estimated residual current is a system-level result, and the branch leakage current ratio has already given the relative share of each branch in the global leakage current, multiplying the two to obtain the branch residual current, and converting the global insulation resistance into the branch insulation resistance according to the same share relationship, can realize the mapping from global quantity to branch quantity.

[0185] In detail, the method for obtaining the positive bus voltage to ground and the negative bus voltage to ground corresponding to the bus voltage is as follows: taking the power supply midpoint or the combined midpoint as a reference, the potential of the positive bus relative to the reference point and the midpoint voltage are combined to form the positive bus voltage to ground, and the potential of the negative bus relative to the reference point and the midpoint voltage are combined to form the negative bus voltage to ground.

[0186] In detail, the integration method of the branch weighted integral is as follows: within one half-pulse width, the product of the sign-aligned transient backflow component and the exponential decay coefficient corresponding to each branch is accumulated point by point, and the branch weighted integral corresponding to each branch is obtained after the accumulation is completed.

[0187] In detail, when the sum of the weighted integrals of all branches is close to zero, the method for handling the leakage current ratio of the branch is as follows: compare the sum with the preset noise floor safety threshold. If it is less than the threshold, it is determined to be in an extremely high insulation health state. Stop outputting the leakage current ratio of each branch and assign an initial constant to each branch. Then reset the injection time for the next round and calculate again.

[0188] In detail, when the leakage current ratio of each branch is close to 0, the calculation and protection method for the insulation resistance of the branch is as follows: limit the insulation resistance of the branch corresponding to the branch to a high resistance value, while retaining the sorting result of the leakage current ratio of the branch corresponding to the branch.

[0189] Preferably, the total return current component is reconstructed using the capacitance time constant and the insulation time constant to generate a dynamic coefficient. This dynamic coefficient is then used to fuse the total leakage current corresponding to the steady-state leakage component with the global insulation resistance. The sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round, including:

[0190] The reduction reflux component is generated using the following calculation formula:

[0191]

[0192] The restoration error and the dynamic coefficient are obtained using the following formula:

[0193]

[0194]

[0195] The combined global insulation resistance and combined total leakage current are calculated using the following formulas:

[0196]

[0197]

[0198] Output the residual current and insulation resistance of the fused branch for each branch according to the following calculation formula:

[0199]

[0200]

[0201] The duration of the next injection round is calculated using the following formula:

[0202]

[0203] in, For time variables, For the reduced reflux component, The total reflux charge, The capacitor weight is... The capacitor time constant is... The insulation time constant is... It is a natural constant. The restoration error is... The width of the single half-pulse, Align the total return flow component with the symbols. The dynamic coefficient is... For the fused global insulation resistance, The global insulation resistance is... The effective ground stress, The total leakage current is... The total leakage current is the fused current. For the global estimate of the residual current, Branch number, The remaining current of the fused branch corresponding to each branch. The percentage of leakage current in the aforementioned branch. The insulation resistance of the fused branch corresponding to each branch is... The duration of the next injection round, The symbol for absolute value calculation. This is the symbol for time integration calculation.

[0204] The restored reflux component is an estimated reflux process obtained by reconstructing the sign-aligned total reflux component using the capacitance time constant, the insulation time constant, the capacitance weight, and the total reflux charge. It is used to verify the consistency between the model and the measured process.

[0205] The restoration error is the difference between the symbol alignment total reflow component and the restoration reflow component, obtained by time integration and normalization, and is used to characterize the current reconstruction quality.

[0206] The dynamic coefficient is a confidence level generated from the reduction error and is used to determine the relative weights of steady-state and transient results in the fused output.

[0207] The fused global insulation resistance is the global insulation output obtained by weighting the global insulation resistance with another global insulation resistance estimate using the dynamic coefficient.

[0208] The total leakage current is obtained by weighting the total leakage current under steady state and the estimated global residual current obtained under transient state by the dynamic coefficients, in order to prevent variable aliasing and overwriting of physical quantities with the same name in the data fusion step.

[0209] The fused branch residual current is the branch-level fused output obtained by mapping the total fused leakage current to each branch according to the leakage current ratio of the branch.

[0210] The fused branch insulation resistance is the branch-level fused output obtained by mapping the fused global insulation resistance to each branch according to the leakage current ratio of the branch.

[0211] The next injection duration is the time length used when the positive and negative symmetrical pulse injection is executed in the next round, which is used to adaptively match the fast and slow responses of the current system.

[0212] In detail, because the symbol-aligned total return current component contains both a faster decay portion related to the capacitance time constant and a slower decay portion related to the insulation time constant, these two portions can be resynthesized into the reduced return current component using the capacitance weight and the total return current charge.

[0213] In detail, since the degree of fit between the restored reflux component and the symbol-aligned total reflux component directly reflects the credibility of the current model, the difference between the two is integrated over time and normalized to form the restoration error. The dynamic coefficient is then generated from the restoration error, which can transform the model credibility into a quantity that can be directly used for weighted fusion.

[0214] In detail, because the total leakage current is closer to steady-state information, while the global insulation resistance and the global estimated residual current are closer to transient identification information, a more stable global output can be obtained by continuously weighting these two types of results using the dynamic coefficient.

[0215] In detail, since the branch leakage current ratio has already established a proportional mapping relationship from the system-level result to the branch-level result in the previous stage, the fused global insulation resistance and the fused total leakage current can still be output as the fused branch insulation resistance and the fused branch residual current in the same proportion.

[0216] In detail, since the next round of injection needs to cover both the rapid changes corresponding to the capacitance time constant and the slow changes corresponding to the insulation time constant, the sum of the two is used as the duration of the next round of injection, which allows the next round of injection time window to cover both main processes simultaneously.

[0217] In detail, the method for constructing the reduced reflux component by combining the capacitor time constant, the insulation time constant, the capacitor weight, and the total reflux charge is as follows: the reduced reflux component is obtained by adding the attenuation part corresponding to the capacitor time constant and the attenuation part corresponding to the insulation time constant, wherein the proportion of the former is determined by the capacitor weight, and the proportion of the latter is determined by subtracting the capacitor weight from the value one.

[0218] In detail, when the total reflux charge is close to 0, the restoration error is handled as follows: instead of directly using the total reflux charge as the divisor, the dynamic coefficient of this round is stopped from being output, and the data of the next round is collected again.

[0219] In detail, when the total leakage current is close to 0, the method of using the dynamic coefficient to weight the global insulation resistance and the total leakage current is as follows: prioritize outputting the result corresponding to the global insulation resistance and the global estimated residual current, and reduce the influence of the total leakage current in the fusion.

[0220] In detail, the method of summing the capacitance time constant and the insulation time constant as the next injection duration is as follows: the next injection duration simultaneously covers the rapid decay phase corresponding to the capacitance time constant and the slow decay phase corresponding to the insulation time constant, and a fixed protection delay interval is forcibly introduced at the pulse switching boundary to wait for the residual transient charge to be discharged, thereby ensuring that the next injection time window is consistent with the current system response time scale and that the signals do not interfere with each other.

[0221] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0222] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A pulse-injection method for dual-parameter detection and estimation of residual current and insulation resistance, characterized in that, include: Positive and negative symmetrical pulses are injected between the power supply midpoint and the grounding terminal, and the differential current, midpoint voltage and bus voltage of each branch are collected simultaneously. The differential current and the midpoint voltage are symmetrically decomposed to separate the steady-state leakage current component and the transient return current component, and the total leakage current corresponding to the steady-state leakage current component is obtained. The time integral of the total return current component generated by superimposing the transient return current components of each branch is calculated to obtain the capacitance time constant, insulation time constant and capacitance weight. Based on the capacitance weight, the insulation charge is extracted, and the transient return current component of the midpoint voltage is weighted using the insulation time constant to obtain the reference voltage, and the global insulation resistance is calculated. The transient return current component of each branch is weighted using the insulation time constant to obtain the branch leakage current ratio. Combined with the global insulation resistance and the bus voltage, the branch insulation resistance and branch residual current are output. The total return current component is reconstructed using the capacitance time constant and the insulation time constant to generate a dynamic coefficient. The total leakage current and the global insulation resistance are then fused using the dynamic coefficient, and the sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round.

2. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 1, characterized in that, A symmetrical positive and negative pulse is injected between the power supply neutral point and the grounding terminal, and the differential current, neutral point voltage, and bus voltage of each branch are collected synchronously, including: The power supply midpoint is obtained. When the power supply system has a physical midpoint, the physical midpoint is used as the power supply midpoint. When the power supply system does not have the physical midpoint, two resistors with equal resistance are connected in series between the positive bus and the negative bus. The connection point of the two resistors is used as the composite midpoint, and the composite midpoint is used as the power supply midpoint. Construct the positive and negative symmetrical pulse consisting of a continuous first half-pulse and a second half-pulse, wherein the first half-pulse and the second half-pulse have equal amplitudes, opposite polarities, and the same width per half-pulse, so that the net charge of the positive and negative symmetrical pulse is zero. The positive and negative symmetrical pulses are applied between the power supply midpoint and the grounding terminal, and the differential current, midpoint voltage and bus voltage of each branch are synchronously collected at a preset sampling frequency.

3. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 2, characterized in that, The differential current and the midpoint voltage are symmetrically decomposed to separate the steady-state leakage current component and the transient return current component, and the total leakage current corresponding to the steady-state leakage current component is obtained, including: Fold the time window corresponding to the second half-pulse back to the time window corresponding to the first half-pulse. At any time corresponding to the first half-pulse, obtain the differential current at the current time and the differential current at a time delayed by one half-pulse width. Half of the difference between the differential current at the current moment and the differential current at a moment delayed by one half-pulse width is taken as the transient return current component corresponding to the differential current. Half of the sum of the differential current at the current moment and the differential current at a moment delayed by one half-pulse width is taken as the steady-state leakage current component corresponding to the differential current. Obtain the midpoint voltage at the current moment and the midpoint voltage at a moment delayed by one half-pulse width; Half of the difference between the midpoint voltage at the current moment and the midpoint voltage at a moment delayed by one half-pulse width is taken as the transient return current component corresponding to the midpoint voltage. Half of the sum of the midpoint voltage at the current moment and the midpoint voltage at a moment delayed by one half-pulse width is taken as the steady-state leakage current component corresponding to the midpoint voltage. The steady-state leakage current components of the differential current corresponding to the same moment in each branch are summed and their absolute values ​​are extracted. Time integration and average value calculation are performed within the time span corresponding to the single half-pulse width to obtain the total leakage current corresponding to the steady-state leakage current components.

4. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 3, characterized in that, The time integral of the total return current component generated by superimposing the transient return current components of each branch is calculated to obtain the capacitance time constant, insulation time constant, and capacitance weight, including: The total return current component is obtained by summing the transient return current components of the differential currents of each branch at the same time. First, the total return current component is integrated over time within one half-pulse width. The sign of the integration result is used as the overall sign. Then, the total return current component is uniformly adjusted to the same direction as the overall sign to generate a sign-aligned total return current component. The time integral of the sign-aligned total return current component within one half-pulse width is used as the normalization reference. The sign-aligned total return current component at each moment is divided by the normalization reference to generate the normalized return current density. The normalized reflux density is multiplied by the first power of time, the second power of time, and the third power of time, respectively, and time integration is performed within the time span corresponding to the single half-pulse width to obtain the first-order time integral, the second-order time integral, and the third-order time integral, respectively. Calculate the first intermediate quantity and the second intermediate quantity based on the first-order time integral, the second-order time integral and the third-order time integral; Solve the quadratic equation based on the first intermediate quantity and the second intermediate quantity, and take the smaller time root as the capacitance time constant and the larger time root as the insulation time constant. Calculate the first difference between the insulation time constant and the first time integral, and divide the first difference by the difference between the insulation time constant and the capacitance time constant to obtain the capacitance weight.

5. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 4, characterized in that, Based on the capacitance weights, insulation charge is extracted. A reference voltage is obtained by weighting the transient return current component of the midpoint voltage using the insulation time constant. The global insulation resistance is then calculated, including: The total return charge is obtained by integrating the symbol-aligned total return component over the time span corresponding to the single half-pulse width. Obtain the second difference between the first value and the capacitor weight, and multiply the second difference by the total return charge to obtain the insulating charge; The transient return current component of the midpoint voltage is integrated and its sign is aligned to generate the sign-aligned transient return current component corresponding to the midpoint voltage. An exponential decay coefficient is constructed using the natural constant as the base and the negative of the ratio of the time variable to the insulation time constant as the exponent. Multiply the sign-aligned transient backflow component corresponding to the midpoint voltage by the exponential decay coefficient and integrate it over time within the time span corresponding to the single half-pulse width to obtain the first weighted integral; The exponential decay coefficient is integrated over the time span corresponding to the single half-pulse width to obtain the second weighted integral. Divide the first weighted integral by the second weighted integral to obtain the reference voltage; The global insulation equivalent capacitance is obtained by dividing the insulation charge by the reference voltage. The global insulation resistance is obtained by dividing the insulation time constant by the global insulation equivalent capacitance.

6. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 5, characterized in that, The transient return current component of each branch is weighted using the insulation time constant to obtain the branch leakage current ratio. Combined with the global insulation resistance and the bus voltage, the branch insulation resistance and branch residual current are output, including: The transient return current components corresponding to the differential current of each branch are sign-aligned to generate the sign-aligned transient return current components corresponding to each branch. Multiply the sign-aligned transient backflow component corresponding to each branch by the exponential decay coefficient and integrate it over the time span corresponding to the single half-pulse width to obtain the branch weighted integral corresponding to each branch. Divide the weighted integral of each branch by the sum of the weighted integrals of all branches to obtain the leakage rate of each branch. Obtain the positive bus voltage to ground and the negative bus voltage to ground corresponding to the bus voltage; The effective ground stress is obtained by summing the absolute values ​​of the positive bus voltage to ground and the negative bus voltage to ground and taking the average value. The effective ground stress is divided by the global insulation resistance to obtain the global estimated residual current. Multiply the leakage current ratio of each branch by the estimated global residual current to output the residual current of each branch. Divide the global insulation resistance by the leakage current ratio of each branch to output the insulation resistance of each branch.

7. The pulse injection-type dual-parameter detection and estimation method for residual current and insulation resistance according to claim 6, characterized in that, The total return current component is reconstructed using the capacitance time constant and the insulation time constant to generate a dynamic coefficient. This dynamic coefficient is then used to fuse the total leakage current and the global insulation resistance. The sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round, including: The restoration error is obtained by constructing a restored reflux component by combining the capacitor time constant, the insulation time constant, the capacitor weight, and the total reflux charge; and by calculating the integral of the error between the restored reflux component and the sign-aligned total reflux component. The dynamic coefficient is generated by taking the reciprocal of the sum of the numerical value and the restoration error; By using the dynamic coefficients to weight the global insulation resistance and the total leakage current, a fused global insulation resistance and a fused total leakage current are output. The combined global insulation resistance and the combined total leakage current are mapped and output as combined branch residual current and combined branch insulation resistance according to the branch leakage current ratio. The sum of the capacitance time constant and the insulation time constant is used as the injection duration for the next round.

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