Power system with power converter and method of detecting partial discharge in the power system

Abstract

A partial discharge detection technique is provided. In one aspect, a method of detecting partial discharge in a power system having a power electronic converter is provided. A first current signal is captured in response to a first applied voltage. A second current signal is captured in response to a second applied voltage, the second applied voltage being different than the first applied voltage. The first current signal is set as a reference signal. A difference signal is determined based on the second current signal and the reference signal. It is determined whether a partial discharge is present based on the difference signal. The method can be iterated, and for each iteration, the reference signal is updated on a rolling basis to a previously captured current signal measured in response to a previously applied voltage. For each iteration, the applied voltage is also increased or decreased.

Description

Technical Field

[0001] This disclosure relates to the detection of discharge. Background Technology

[0002] Electric systems, such as those found in aircraft electric and hybrid electric propulsion systems, can employ various power electronic converters to control and / or convert electricity. Power electronics-based electric systems can offer advantages such as dynamic speed control and higher energy efficiency. However, certain challenges associated with such electric systems exist, such as reliably detecting partial discharges. The presence of partial discharges can lead to the degradation of insulating materials and other packaging materials that do not possess partial discharge resistance.

[0003] Therefore, improved techniques for detecting partial discharges would be a useful addition to this field. Attached Figure Description

[0004] The specification sets forth a complete and practical disclosure for those skilled in the art, including its best mode, which is referenced in the accompanying drawings, wherein:

[0005] Figure 1 A diagram of a detection system connected to a power system, based on an example aspect of this disclosure, is provided;

[0006] Figure 2 Provided a description Figure 1 The detection system can detect and Figure 1 A sequence diagram illustrating example modes of partial discharge associated with a power system;

[0007] Figure 3 A graph is provided to display various signals, including a first applied voltage and a first current signal captured in response to the first applied voltage;

[0008] Figure 4 It provides graphs displaying various signals, including a second applied voltage, a second current signal captured in response to the second applied voltage, a reference signal, and a difference signal;

[0009] Figure 5 It provides graphs displaying various signals, including a third applied voltage, a third current signal captured in response to the third applied voltage, an updated reference signal, and a difference signal determined based on the updated reference signal and the third current signal;

[0010] Figure 6 Provided Figure 5 A magnified view of the curve graph;

[0011] Figure 7 A flowchart of a method for detecting partial discharge according to an exemplary aspect of this disclosure is provided;

[0012] Figure 8 A flowchart of a method for detecting partial discharge extinction voltage according to an exemplary aspect of this disclosure is provided;

[0013] Figure 9 Provided Figure 1 A detailed system diagram of the signal analyzer for the detection system; and

[0014] Figure 10 Example carriers are provided based on example embodiments of this topic. Detailed Implementation

[0015] Reference will now be made in detail to the present embodiments of this disclosure, one or more examples of which are illustrated in the accompanying drawings. Detailed description uses numerals and letter designations to refer to features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to refer to similar or analogous portions of this disclosure.

[0016] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0017] Unless otherwise specified herein, the terms “connection,” “fixation,” “attachment,” etc., refer to direct connection, fixation, or attachment, as well as indirect connection, fixation, or attachment via one or more intermediate components or features.

[0018] Unless the context clearly indicates otherwise, the singular forms “a,” “one,” and “the” include plural references.

[0019] In the context of this term, "at least one", such as "at least one of A, B and C", means only A, only B, only C, or any combination of A, B and C.

[0020] As used throughout the specification and claims, approximate language is applied to modify any quantitative expression that allows for variation without altering the underlying function. Therefore, values ​​modified by one or more terms such as “about,” “approximately,” and “substantially” are not limited to specified exact values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to margins of 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins may apply to a single value, to either or both endpoints of a defined numerical range, and / or to margins within a range between endpoints.

[0021] Throughout this specification and claims, scope limitations are combined and interchanged, and such scopes are identified and include all subscopes contained therein, unless the context or language otherwise indicates. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0022] Power electronic converters can provide dynamic control and higher energy efficiency for power systems. However, as mentioned above, such power electronic-based power systems are susceptible to partial discharges, or partial discharges that only partially bridge the insulation between conductors. The presence of partial discharges can lead to degradation of the insulation system and other packaging materials. For example, detecting partial discharges can be advantageous for detecting and / or predicting insulation system failures, developing maintenance plans, and monitoring component health. However, reliably detecting partial discharges is often difficult, especially at high switching frequencies. At high switching frequencies, partial discharge signals may be hidden in noise, such as transient current responses or current clusters due to voltage changes. Voltage changes occur due to the switching of the power converter's switching mechanism.

[0023] According to the inventive aspect of this disclosure, a detection technique is provided that can reliably detect partial discharge even at high switching frequencies. Typically, the disclosed detection technique is implemented using an iterative detection sequence that uses a reference signal updated on a rolling basis. For example, the reference signal can be updated continuously on a rolling basis or in each iteration of the detection sequence. The reference signal is updated on a rolling basis to a previously captured current signal measured in response to a previously applied voltage. The applied voltage increases or changes in each iteration of the detection sequence. For a given iteration, the reference signal and the currently captured current signal measured in response to the currently applied voltage are used to determine a difference signal. For example, the difference signal can be determined by subtracting the reference signal from the currently applied current signal. This difference signal can be used to determine whether a partial discharge exists at the currently applied voltage. For example, if the amplitude of the difference signal exceeds a threshold, it is determined that a partial discharge exists at the currently applied voltage. In this respect, a partial discharge initiation voltage can be determined. When a partial discharge actually exists, the amplitude of the difference signal is typically much larger than its expected amplitude. The partial discharge occurs suddenly and the amplitude exceeds the expected amplitude.

[0024] In some implementations, once a partial discharge is determined to exist at the currently applied voltage—that is, once the partial discharge initiation voltage is reached—the detection sequence can be iterated once or multiple times to confirm the presence of the partial discharge. In this regard, the applied voltage can be further increased. For example, the detection sequence can be iterated until the applied voltage is greater than or equal to a predetermined percentage of the partial discharge initiation voltage, such as 10%, etc.

[0025] Furthermore, in some implementations, a detection sequence can be executed to find the partial discharge extinction voltage, or the voltage at which the partial discharge pulse stops occurring when the applied voltage begins to decrease from an applied voltage higher than the partial discharge initiation voltage. For example, for each iteration of the detection sequence, the voltage can be decreased, and if the amplitude of the difference signal does not exceed a threshold, the currently applied voltage associated with that iteration is determined as the partial discharge extinction voltage.

[0026] The disclosed detection technique offers numerous advantages, benefits, and / or technical effects. For example, it typically allows for the detection of discharge activity without signal loss across the entire frequency bandwidth of kilohertz (kHz) and megahertz (GHz). Furthermore, it is noteworthy that partial discharge signals hidden within noise (e.g., transient current responses or current clusters) can be detected more easily because the disclosed detection technique is time-domain based rather than frequency-domain based. In addition to determining the presence of partial discharge, various characteristics of the detected partial discharge signal can be determined, such as the pulse shape, pulse amplitude, and / or frequency associated with the partial discharge signal. The disclosed technique also allows for the detection of not only the partial discharge initiation voltage but also the partial discharge extinction voltage. The detection technique can be implemented "in reverse" to detect the partial discharge extinction voltage. This detection technique may also offer other advantages and benefits not explicitly stated herein.

[0027] Furthermore, the disclosed testing techniques can be implemented for various applications. For example, the disclosed testing techniques can be implemented during component development or in the field. For instance, this testing technique can allow for fine characterization of test samples and prototypes during the development phase and during long-term testing using high-accelerated life testing to help estimate and determine future field reliability. In the field, this testing technique can be used to monitor discharge activity in pulse-driven systems, which can help estimate the health status of electrical components and prevent failures and unexpected downtime.

[0028] This testing technology is applicable to any industry that provides power electronics-based power systems. Example industries include, but are not limited to, the aerospace industry (e.g., for electric and hybrid electric aircraft), the power generation industry, the automotive industry, the marine industry, and the like. In some example embodiments, the disclosed testing technology can be used for various aerospace applications, such as for testing the quality of equipment before shipment; post-delivery inspection in wings or service workshops; and / or for active monitoring of power systems and / or their components during flight.

[0029] Figure 1A diagram of a system 100 according to an exemplary aspect of this disclosure is provided. For this embodiment, system 100 is an electrical system. System 100 includes a voltage source 110. For example, voltage source 110 may be one or more batteries. Voltage source 110 is electrically connected to power electronic devices, which in this embodiment include a power converter 120 having a plurality of switching devices 122. The switching devices 122 may be switched in a controlled manner to control the drawing and / or supply of power from voltage source 110 to voltage source 110. As an example, one or more switching devices 122 may be silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs). Power converter 120 is in turn electrically connected to a load 130. Load 130 may be, for example, a motor.

[0030] The detection system 140 is electrically connected to the load 130, for example, via a power bus. Typically, the detection system 140 is configured to detect partial discharges associated with system 100. The detection system 140 includes a sensing device, which in this embodiment is a current sensor 150 electrically connected to the load 130. The current sensor 150 is operable to measure or sense current. In alternative embodiments, the current sensor 150 may be located at other suitable locations, such as between the power converter 120 and the load 130. Other locations are also possible.

[0031] The detection system 140 also includes a signal analyzer 160. The signal analyzer 160 may include one or more processors 162, one or more memory devices 164, and one or more displays 166. For example, the signal analyzer 160 may be or include an oscilloscope. Typically, the signal analyzer 160 is configured to receive, process, and generate signals, and render images of these signals, such as an image of a current signal captured by a current sensor 150 in response to voltage changes caused by modulation of the switching device 122 of the power converter 120. A more detailed disclosure of the signal analyzer 160 is available on [date / details to be provided]. Figure 9 It was found in the subsequent text.

[0032] Now for reference Figure 1 and 2 , Figure 2 Sequence diagrams are provided illustrating an example mode in which the detection system 140 can detect partial discharges associated with system 100. Specifically, Figure 2 Example detection sequences are provided that can be implemented to detect partial discharges associated with system 100.

[0033] As shown in the figure, at a first time t1, a first voltage V1 is applied. For example, the switching device 122 of the power converter 120 can be controlled to apply the first voltage V1. Modulation of the switching device 122 can transfer power from the voltage source 110 to the load 130 and vice versa. When the first voltage V1 is applied, the current sensor 150 can capture a first current signal I1 in response to the first applied voltage V1. The captured first current signal I1 can be received by one or more processors 162. The received first current signal I1 can be saved or stored on one or more memory devices 164. In addition, the first current signal I1 can be displayed on a display 166.

[0034] For example, Figure 3 Graphs displaying various signals are provided, including a first applied voltage V1 and a first current signal I1 captured in response to the first applied voltage V1. The signal is in... Figure 3 The curve is presented as a function of time. For example... Figure 3 As shown in the example, the first applied voltage V1 is pulsed, for example, in the form of a square wave. In this example embodiment, the first applied voltage V1 pulses at +750V / -500V, presenting a peak-to-peak applied voltage of 1250V. Each pulse P has an associated falling edge FE and rising edge RE. Figure 3 (Only one pulse is marked in the text). Each falling edge FE and each rising edge RE corresponds to a change in the position or modulation of the switching device 122 of the power converter 120. The falling edge FE and rising edge RE can also be represented as switching edges.

[0035] like Figure 3 As shown, the captured first current signal I1 has a transient response at each falling edge FE and each rising edge RE. That is, the first current signal I1 experiences a transient response each time the switching device 122 is switched. It should be understood that changes in voltage cause changes in current. This is evident by the relatively large spikes in the first current signal I1 at the switching edges corresponding to the pulse of the first voltage V1. As described above, the first current signal I1 can be captured by the current sensor 150, received by one or more processors 162, stored in one or more memory devices 164, and presented on the display 166, as shown. Figure 3 As shown.

[0036] Return to Figure 1 and 2 At time t2, the detection sequence continues. Specifically, at time t2, one or more processors 162 can set the first current signal I1 as the reference signal I. REF The first current signal I1 can alternatively be set as the reference signal I at time t1. REFFurthermore, at time t2, a second voltage V2 is applied. The switching device 122 of the controllable power converter 120 is configured to apply the second voltage V2. The second voltage V2 differs from the first voltage V1. Specifically, the second voltage V2 can be greater than the first voltage V1. The second voltage V2 can be increased by a predetermined voltage increment or step, for example, by 50V. In some embodiments, for example, the predetermined voltage increment or step can be between 50 and 300V.

[0037] When a second voltage V2 is applied, the current sensor 150 can capture a second current signal I2 in response to the applied voltage V2. The captured second current signal I2 can be received by one or more processors 162. The received second current signal I2 can be stored or saved on one or more memory devices 164. In addition, the second current signal I2 can be displayed on a display 166.

[0038] One or more processors 162 of the detection system 140 may be based at least in part on the second current signal I2 and the reference signal I. REF The difference signal IΔ2 is determined. For example, in some embodiments, this can be achieved by subtracting the reference signal I from the second current signal I2. REF To determine the difference signal IΔ2, or mathematically expressed as IΔ2 I2 I REF Therefore, in such an embodiment, the reference signal I REF It can be defined as the current signal or, in this case, the second current signal I2 and the reference signal I. REF The difference between them.

[0039] In other example embodiments, the reference signal I can be used. REF Multiply by a correction factor (which is expressed as the quotient defined by dividing the currently applied voltage (in this case, the second voltage V2) by the previously applied voltage (in this case, the first voltage V1), and then subtract the reference signal I from the second current signal I2. REF The difference signal IΔ2 is determined by multiplying it with the correction coefficient, or mathematically expressed as IΔ2 in this case. I2 (I) REF (V2 / V1)). As described above, the reference signal I REF Multiplying by a correction factor can further increase partial detection sensitivity and further reduce error when using linear extrapolation. For example, in embodiments where the first applied voltage V1 and the second applied voltage V2 are relatively close to each other, a linear response can be assumed within a local range. Based on the current response under the first applied voltage V1, in this case, the reference signal I...REF The linear extrapolation of the current response under the second applied voltage V2 should be, or approximately, I2' = I REF (V2 / V1), therefore the difference is IΔ2 = I2 – I2', that is, IΔ2 I2 (I) REF (V2 / V1)). If there is no partial discharge, the difference signal IΔ2 should be infinitesimal. If there is a partial discharge, the difference signal IΔ2 will appear as noise beyond the time domain.

[0040] The resulting difference signal IΔ2 can be displayed on display 166. One or more processors 162 can then determine the presence of partial discharge based at least in part on the difference signal IΔ2. For example, if the amplitude of the difference signal IΔ2 exceeds a threshold, a partial discharge is determined to exist. Conversely, if the amplitude of the difference signal IΔ2 does not exceed the threshold, a partial discharge is determined not to exist.

[0041] Continuing with the example above, Figure 4 Graphs displaying various signals are provided, including the second applied voltage V2, the second current signal I2 captured in response to the second applied voltage V2, and the reference signal I. REF The difference signal IΔ2. As described above, the second current signal I2 can be captured by the current sensor 150, received by one or more processors 162, stored in one or more memory devices 164, and presented on the display 166, for example, as... Figure 4 As shown. In this case, the reference signal I REF A first current signal I1 is set to be captured in response to a first applied voltage V1. Figure 4 In the process, due to the voltage difference between the first voltage V1 and the second voltage V2, the reference signal I... REF It is slightly offset from the second current signal I2, as explained below.

[0042] like Figure 4 As shown in the example, the second applied voltage V2 is pulsed, for example, in the form of a square wave. In this example, the second applied voltage V2 pulses at +800V / -500V, presenting a peak-to-peak applied voltage of 1300V. Therefore, the first voltage V1 (applied at a peak-to-peak of 1250V) Figure 3 Between the first voltage I1 and the second voltage V2 applied at a peak-to-peak value of 1300V, the voltage increased by 50V. That is, the second voltage V2 is 50V greater than the first voltage V1. Therefore, the second current signal I2 has a slightly different response than the first current signal I1. The first current signal I1 is set as the reference signal I in this iteration of the sequence. REFThe difference between the first and second current responses I1 and I2 causes the resulting difference signal IΔ2 to have a relatively large amplitude at the time corresponding to the current transient caused by the modulation of the switching device 122. For example... Figure 4 As shown, there is a relatively large "bump" or amplitude spike at the time corresponding to the modulation of the switching device 122. Such a spike or bump is expected.

[0043] Using the difference signal IΔ2 determined by one or more processors 162, the one or more processors 162 can determine whether a partial discharge exists. For example, when the amplitude of the difference signal IΔ2 exceeds a threshold, for instance... Figure 4 If either the first threshold T1 or the second threshold T2 is indicated, partial discharge is determined to be present. In this example, the positive amplitude spikes of the difference signal IΔ2 occurring at the time corresponding to the rising edge of the pulse do not exceed the first threshold T1, and the negative amplitude spikes of the difference signal IΔ2 occurring at the time corresponding to the falling edge of the pulse do not exceed the second threshold T2. In this respect, no partial discharge was detected during this iteration of the detection sequence.

[0044] Back to Figure 1 and Figure 2 At time t3, the detection sequence iterates again. It is worth noting that for each iteration of the detection sequence, the reference signal I can be set or updated on a rolling basis using the previously captured current signal. REF Therefore, at time t3, one or more processors 162 set the second current signal I2 as the reference signal I. REF Furthermore, at time t3, a third voltage V3 is applied. The switching device 122 of the controllable power converter 120 applies the third voltage V3. The third voltage V3 differs from the second voltage V2. Specifically, the third voltage V3 can be greater than the second voltage V2. The third voltage V3 can be increased by a predetermined voltage increment, for example, by 50V. In some embodiments, the predetermined voltage increment can be set as a constant step size or value. That is, the predetermined voltage increment can be fixed between iterations (e.g., such that the voltage increases by 25V for each iteration of the detection sequence). In other embodiments, the predetermined voltage increment can be variable. For example, the predetermined voltage increment can decrease or be reduced as the applied voltage approaches the predicted partial discharge initiation voltage associated with a particular load or sample. For example, as the applied voltage approaches the predicted partial discharge initiation voltage, the predetermined voltage increment can decrease from 50V to 25V.

[0045] When a third voltage V3 is applied, the current sensor 150 can capture a third current signal I3 in response to the applied third voltage V3. The captured third current signal I3 can be received by one or more processors 162. The received third current signal I3 can be saved or stored on one or more memory devices 164. In addition, the third current signal I3 can be displayed on a display 166.

[0046] One or more processors 162 of the detection system 140 may be based at least in part on the third current signal I3 and the reference signal I. REF This is used to determine the difference signal IΔ3. For example, the reference signal I can be subtracted from the third current signal I3. REF The difference signal IΔ3 is then determined. The determined difference signal IΔ3 can be displayed on display 166. One or more processors 162 can then determine, at least in part, whether a partial discharge exists based on the difference signal IΔ3. For example, if the amplitude of the difference signal IΔ3 exceeds a threshold, a partial discharge is determined to exist. Conversely, if the amplitude of the difference signal IΔ3 does not exceed a threshold, a partial discharge is determined not to exist.

[0047] Continuing with the example above, Figure 5 Graphs displaying various signals are provided, including the third applied voltage V3, the third current signal I3 captured in response to the third applied voltage V3, and the reference signal I updated to the second current signal I2. REF The sum and difference signal IΔ3. The third current signal I3 can be captured by the current sensor 150, received by one or more processors 162, stored in one or more memory devices 164, and presented on the display 166, for example, as Figure 5 As shown. In this case, the reference signal I REF A second current signal I2 is configured to be captured in response to a second applied voltage V2. Figure 5 In the middle, due to the voltage difference between the second voltage V2 and the third voltage V3, the reference signal I REF It deviates slightly from the third current signal I3, as explained in more detail below.

[0048] like Figure 5 As shown, the third applied voltage V3 is pulsed, for example, in the form of a square wave. In this example, the third applied voltage V3 pulses at +850V / -500V, presenting a peak-to-peak applied voltage of 1350V. Therefore, the second voltage V2 (applied at a peak-to-peak of 1300V) Figure 4 Between the applied peak-to-peak voltage V3 and the third voltage V2, the voltage increases by 50V. In other words, the third voltage V3 is 50V greater than the second voltage V2. Therefore, the third current signal I3 has a slightly different response than the second current signal I2, which is set as the reference signal I in this iteration of the sequence.REF The difference between the second and third current responses I2 and I3 results in a difference signal IΔ3 with a relatively large amplitude at the time corresponding to the current transient caused by the modulation of the switching device 122. A relatively large "bump" or spike at the time corresponding to the modulation of the switching device 122 is expected, but an amplitude spike exceeding the expectation may indicate the presence of partial discharge.

[0049] Specifically, using the difference signal IΔ3 determined by one or more processors 162, the one or more processors 162 can determine whether a partial discharge exists. For example, when the amplitude of the difference signal IΔ3 exceeds a threshold, for instance... Figure 5 If either the first threshold T1 or the second threshold T2 is indicated, partial discharge is determined to exist. In this example, the first positive amplitude spike +SP1 of the difference signal IΔ3, occurring at the rising edge of one of the pulses, exceeds the first threshold T1. In this respect, at this time, the amplitude of the first positive amplitude spike +SP1 is greater than the expected amplitude. The amplitude of the difference signal IΔ3 exceeding the threshold indicates the presence of partial discharge. Furthermore, the first negative amplitude spike -SP1 and the second negative amplitude spike -SP2 of the difference signal IΔ3, occurring at the falling edge of each pulse, exceed the second threshold T2. In this respect, at this time, the amplitudes of both the first negative amplitude spike -SP1 and the second negative amplitude spike -SP2 are greater than the expected amplitude, indicating the presence of partial discharge in system 100. Figure 5 As shown in the example, partial discharge occurs suddenly and the magnitude exceeds the expected magnitude.

[0050] The expected amplitude at the switching edge of the pulse can be accurately predicted, at least because current transients or amplitude spikes in the current increase linearly or substantially linearly with increasing voltage. Therefore, assuming the voltage increases from a previous iteration of the detection sequence, a threshold can be set based on the expected amplitude of the difference signal at the switching edge. The use of the expected amplitude allows for accurate threshold setting regardless of the predetermined voltage increase between detection sequence iterations. Accurate threshold setting enables accurate detection of partial discharges.

[0051] Figure 6 Depicting Figure 5 A magnified view of the curve graph. Figure 6 In the diagram, the transient response of the third current signal I3 to the peak-to-peak variation of the applied third voltage V3 is shown more clearly. The transient response of the second current signal, which is... Figure 6 Reference signal I in REF It also displays more clearly. For example... Figure 6As further illustrated, the amplitude spike of the difference signal IΔ3 associated with partial discharge is embedded within current clusters or transient current responses. The generation of the difference signal IΔ3 is a time-domain based signal, allowing for the detection of partial discharges, even when they occur embedded within current transient noise. The amplitude of the difference signal IΔ3 can be analyzed for partial discharges (e.g., compared to a threshold), regardless of whether the spikes associated with switching (which may or may not indicate partial discharge) are embedded within current transients or clusters. This advantage is particularly useful for applications with higher switching frequencies.

[0052] Furthermore, in addition to determining the presence of partial discharge, various characteristics of the partial discharge signal can be determined. For example, the pulse shape, pulse amplitude, and / or frequency associated with the partial discharge signal, as well as other possibilities, can be determined. In this regard, the partial discharge detection technique presented in this paper not only performs pass / fail tests but also allows for the determination of certain characteristics of the detected partial discharge signal.

[0053] like Figure 2 Furthermore, if no partial discharge is detected at time t3 or at another future time, further iterations of the detection sequence can continue in the same manner as described above. Any suitable number of iterations of the detection sequence can be implemented. For example, N iterations can be implemented until the partial discharge initiation voltage is determined, where N is an integer. The detection sequence is generally based on time... This indicates that each time a detection sequence is implemented, the implementation of the detection sequence may include i) responding to a previously applied voltage. At a previous time (e.g., at (Location not shown) The previously captured current signal Set as reference signal I REF ;ii) Capture response to the currently applied voltage The captured current signal The currently applied voltage Different from (e.g., greater than) the previously applied voltage ;iii) based at least in part on the current current signal and reference signal I REF Determine the difference signal ; and iv) determining the presence of partial discharge based at least in part on the difference signal. In light of this disclosure, it will be understood that, in time... (Not shown) During the next iteration of the sequence, in response to the applied voltage The captured current signal It becomes the previously captured current signal and is therefore set as the reference signal I. REF In this way, the reference signal is updated on a rolling basis.

[0054] Figure 7 A flowchart of a method 700 for detecting partial discharge in a power system with a power electronic converter is provided.

[0055] At 702, method 700 includes capturing a first current signal in response to a first applied voltage. For example, multiple switching devices of a power electronic converter may be switched to pulse the first applied voltage (i.e., as a pulse-width modulated signal). Applying the first voltage allows power to be transferred between a voltage source and a load, both of which are electrically connected to the power electronic converter. A current sensor or other current sensor may capture the first current signal in response to the first applied voltage. The captured first current signal may be provided to one or more processors of a signal analyzer. One or more processors may receive the captured first current signal. One or more memory devices of the signal analyzer may store the first current signal.

[0056] At 704, method 700 includes capturing a second current signal in response to a second applied voltage, the second applied voltage being different from a first applied voltage. For example, multiple switching devices of a power electronic converter may be switched to apply the second applied voltage. The switching devices may be controlled to pulse (i.e., as a pulse width modulation signal) the second applied voltage. The second applied voltage may be increased by a predetermined voltage increment or step. In some embodiments, for example, the predetermined voltage increment or step may be between 50 and 300 V. A current sensor may capture the second current signal in response to the second applied voltage. The captured second current signal may be provided to one or more processors of a signal analyzer. One or more processors may receive the captured second current signal. One or more memory devices of the signal analyzer may store the second current signal.

[0057] At 706, method 700 includes setting a first current signal as a reference signal. For example, one or more processors of a signal analyzer may set a stored first current signal as a reference signal.

[0058] At 708, method 700 includes determining a difference signal based at least in part on the second current signal and the reference signal. For example, in some embodiments, one or more processors may subtract the reference signal from the second current signal to determine the difference signal. In other embodiments, one or more processors may determine the difference signal by multiplying the reference signal by a correction factor (which is expressed as a quotient defined by dividing the currently applied voltage (in this case, the second applied voltage) by the previously applied voltage (in this case, the first applied voltage)) and then subtracting the product of the reference signal and the correction factor from the second current signal.

[0059] At 710, method 700 includes determining the presence of a partial discharge based at least in part on a difference signal. For example, one or more processors may determine the presence of a partial discharge by comparing the difference signal to one or more thresholds, such as a first or positive threshold and a second or negative threshold. When the difference signal exceeds a threshold, a partial discharge is determined to be present. Conversely, when the difference signal does not exceed a threshold, a partial discharge is determined not to be present.

[0060] In some implementations, the threshold is set at or within a margin of the expected current amplitude (e.g., within ten percent (10%)). The expected current amplitude may be determined by one or more processors as the expected amplitude of the difference signal at the switching edge of the pulse of the currently applied voltage (in this example, the second applied voltage), the expected amplitude being determined at least in part based on the voltage increment between the currently applied voltage and the previously applied voltage (in this example, the first applied voltage).

[0061] At 712, when it is determined at 710 that a partial discharge has been detected, method 700 can stop and can determine various characteristics associated with the partial discharge signal, such as the pulse shape, pulse amplitude and / or frequency associated with the partial discharge signal.

[0062] At 714, when it is determined at 710 that no partial discharge is detected, method 700, or the detection sequence, can be iterated. This method can be iterated at least once, or iterated any suitable number of times, e.g., until the partial discharge initiation voltage is determined. Notably, with each iteration of method 700, the reference signal is updated on a rolling basis to the previously captured current signal, such that for a given iteration of method 700, the difference signal determined at 708 is determined to be the difference between the current current signal captured in response to the currently applied voltage and the previously captured current signal captured in response to the previously applied voltage. Furthermore, with each iteration of method 700, the currently applied voltage is greater than the previously applied voltage. With each iteration of the method, the currently applied voltage can be increased from the previously applied voltage, for example, between approximately 50 and 300 volts. The currently applied voltage and the previously applied voltage can be applied via pulse width modulation, for example, through rapid switching of multiple switching devices of a power electronic converter.

[0063] In other words, each iteration of method 700 may include capturing a current current signal in response to a currently applied voltage, which is different from a previously applied voltage; setting a previous current signal as a reference signal, which was captured in response to a previously applied voltage; determining a difference signal based at least in part on the current current signal and the reference signal; and determining whether a partial discharge exists based at least in part on the difference signal.

[0064] In some embodiments of method 700, once a partial discharge is determined to be present at the currently applied voltage (e.g., once the partial discharge initiation voltage is reached), the detection sequence can be iterated once or multiple times to confirm the presence of the partial discharge. In this regard, the applied voltage can be further increased or increased. For example, the detection sequence can be iterated until the applied voltage is greater than or equal to a predetermined percentage of the partial discharge initiation voltage, such as 10%, etc.

[0065] Furthermore, a detection sequence can be implemented to find the partial discharge extinction voltage, or the voltage at which the partial discharge pulse stops occurring when the applied voltage is reduced from an applied voltage higher than the partial discharge initiation voltage. In this regard, Figure 2 and aspects of the detection sequence described in the accompanying text and Figure 7 The aspects of method 700 described herein can be applied "in reverse" to detect partial discharge extinction voltage. The detection sequence can be applied "in reverse" because for each iteration of the detection sequence, the voltage can be reduced, and if the amplitude of the difference signal does not exceed a threshold, the currently applied voltage associated with that iteration is determined as the partial discharge extinction voltage. Figure 8 An example method is provided for implementing a detection sequence to detect the partial discharge extinction voltage.

[0066] Figure 8 A flowchart of a method 800 for detecting partial discharge extinction voltage in a power system with a power electronic converter is provided.

[0067] At 802, method 800 includes capturing a first current signal in response to a first applied voltage, the first applied voltage being higher than a partial discharge initiation voltage. For example, multiple switching devices of a power electronic converter may be switched to pulse the first applied voltage (i.e., as a pulse width modulated signal). Applying the first voltage allows power to be transferred between a voltage source and a load, both of which are electrically connected to the power electronic converter. A current sensor or other current sensing device may capture the first current signal in response to the first applied voltage. The captured first current signal may be provided to one or more processors of a signal analyzer. One or more processors may receive the captured first current signal. One or more memory devices of the signal analyzer may store the first current signal.

[0068] At 804, method 800 includes capturing a second current signal in response to a second applied voltage, the second applied voltage being less than a first applied voltage. For example, multiple switching devices of a power electronic converter may be switched to apply the second applied voltage. The switching devices may be controlled to pulse the second applied voltage (i.e., as a pulse width modulation signal). The second applied voltage may decrease from one iteration of method 800 to the next iteration by a predetermined voltage decrease or step size. In some embodiments, for example, the predetermined voltage decrease or step size may be between 50 and 300 V. A current sensor may capture the second current signal in response to the second applied voltage. The captured second current signal may be provided to one or more processors of a signal analyzer. One or more processors may receive the captured second current signal. One or more memory devices of the signal analyzer may store the second current signal.

[0069] At 806, method 800 includes setting a first current signal as a reference signal. For example, one or more processors of a signal analyzer may set a stored first current signal as a reference signal.

[0070] At 808, method 800 includes determining a difference signal based at least in part on the second current signal and the reference signal. For example, in some embodiments, one or more processors may determine the difference signal by subtracting the reference signal from the second current signal. In other embodiments, one or more processors may determine the difference signal by multiplying the reference signal by a correction factor (which is expressed as a quotient defined by dividing the currently applied voltage (in this case, the second applied voltage) by the previously applied voltage (in this case, the first applied voltage)) and then subtracting the product of the reference signal and the correction factor from the second current signal.

[0071] At 810, method 800 includes determining the presence of a partial discharge based at least in part on a difference signal. For example, one or more processors may determine the presence of a partial discharge by comparing the difference signal to one or more thresholds, such as a first or positive threshold and a second or negative threshold. When the difference signal exceeds a threshold, a partial discharge is determined to be present. Conversely, when the difference signal does not exceed a threshold, a partial discharge is determined not to be present. When no partial discharge is detected or present, the partial discharge extinguishing voltage is determined to be or approximately equal to the currently applied voltage.

[0072] In some implementations, the threshold is set at or within a margin of the expected current amplitude (e.g., within ten percent (10%)). The expected current amplitude may be determined by one or more processors as the expected amplitude of the difference signal at the switching edge of the pulse of the currently applied voltage (in this example, the second applied voltage), the expected amplitude being determined at least in part based on the reduction of the voltage between the currently applied voltage and the previously applied voltage (in this example, the first applied voltage).

[0073] At 812, when it is determined at 810 that partial discharge no longer exists, the currently applied voltage is determined as the partial discharge extinction voltage and method 800 can be stopped. Various characteristics associated with the current signal associated with the partial discharge extinction voltage, such as the pulse shape, pulse amplitude, and / or frequency of the signal, can be determined.

[0074] At 814, when it is determined at 810 that partial discharge still exists, method 800, or detection sequence, can be iterated. Method 800 can be iterated at least once, but can be iterated any suitable number of times, e.g., until the partial discharge extinction voltage is determined. Notably, each iteration of method 800 updates the reference signal on a rolling basis to the previously captured current signal, such that for a given iteration of method 800, the difference signal determined at 808 is determined to be the difference between the current current signal captured in response to the currently applied voltage and the previously captured current signal captured in response to the previously applied voltage. Furthermore, each iteration of method 800 involves the currently applied voltage being less than or lower than the previously applied voltage. Each iteration of the method can reduce the currently applied voltage from, for example, between approximately 50 and 300 volts from the previously applied voltage. The currently applied voltage and the previously applied voltage can be applied via pulse width modulation, e.g., by rapid switching of multiple switching devices of a power electronic converter.

[0075] In other words, at each iteration of method 800, method 800 may include capturing a current current signal in response to a currently applied voltage, the currently applied voltage being less than a previously applied voltage; setting a previous current signal as a reference signal, the previous current signal being captured in response to a previously applied voltage; determining a difference signal based at least in part on the current current signal and the reference signal; and determining whether a partial discharge exists based at least in part on the difference signal. When a partial discharge exists, the method iterates as the applied voltage decreases. When no partial discharge exists, the currently applied voltage is determined to be or approximately equal to the partial discharge extinction voltage. As will be understood from the context of method 800, the initial applied voltage in the sequence is greater than the partial discharge initiation voltage.

[0076] According to Figure 7 Method 700 detects the partial discharge initiation voltage associated with the electrical system and / or according to Figure 8 When Method 800 detects a partial discharge extinction voltage, it can take one or more control actions in response.

[0077] In some implementations, for example, one or more components of the system can be controlled in response to the detection of a partial discharge initiation voltage and / or a partial discharge extinction voltage. For example, a power converter or load (e.g., a motor) of the system can be controlled in response to the detection of a partial discharge. The power converter and / or load can be controlled to avoid or otherwise reduce their operation under the conditions / settings that cause the detected partial discharge. Such active control can be particularly useful for systems implemented in the field.

[0078] In other embodiments, upon detection of a partial discharge initiation voltage and / or a partial discharge extinction voltage, one or more notifications may be generated and transmitted to one or more entities, such as system operators, maintenance personnel, system manufacturers, etc. In some embodiments, the notification may indicate the detection of a partial discharge, and in some cases, indicate properties of the partial discharge, such as the pulse shape, pulse amplitude, and / or frequency associated with the partial discharge signal, as well as other possibilities.

[0079] In other implementations, one or more service or maintenance tasks can be scheduled in response to the detection of a partial discharge initiation voltage and / or a partial discharge extinction voltage. For example, one or more service or maintenance tasks can be scheduled to visually inspect the insulation system of one or more components of the system, repair or replace the insulation system of one or more components of the system, repair or replace one or more components of the system, etc. Furthermore, in response to the detection of a partial discharge initiation voltage and / or a partial discharge extinction voltage, data capturing partial discharge detection and the surrounding conditions can be transmitted to a monitoring system, such as a predictive and health monitoring system. Such a monitoring system can use the data to track component health status and make recommendations and predictions regarding the service of one or more components of the system. Such a monitoring system can prevent malfunctions and unexpected downtime.

[0080] Figure 9 Detailed system diagrams of a signal analyzer 160 according to exemplary embodiments of the present disclosure are provided. As indicated, the signal analyzer 160 may include one or more processors 162 and one or more memory devices 164. The one or more processors 162 may include any suitable processing means, such as a microprocessor, microcontroller, integrated circuit, logic device, and / or other suitable processing means. The one or more memory devices 164 may include one or more computer-executable or computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard disk drives, flash drives, and / or other memory devices.

[0081] One or more memory devices 164 may store information accessible by one or more processors 162, including computer-readable or computer-executable instructions 164A executable by one or more processors 162. Instructions 164A may be any set of instructions that, when executed by one or more processors 162, cause one or more processors 162 to perform operations. In some embodiments, instructions 164A may be executed by one or more processors 162 to cause one or more processors 162 to perform operations, such as any operations and functions configured for the signal analyzer 160. Instructions 164A may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions 164A may be executed on processor 162 in logically and / or virtually separate threads. Memory device 164 may further store data 164B accessible by processor 162. For example, data 164B may include models, lookup tables, databases, etc.

[0082] The signal analyzer includes one or more displays 166. The one or more displays 166 can display various images, such as those from the current sensor 150 (…). Figure 1 The image captured by the signal analyzer 160 may also include components for communication with, for example, detection system 140 and / or system 100 via a communication network. Figure 1 Network interface 168 is a network interface for communicating with other components of the network interface. Network interface 168 may include any suitable components for communicating with one or more network interfaces, including, for example, transmitters, receivers, ports, controllers, antennas and / or other suitable components.

[0083] Figure 10 An example vehicle 900 is provided according to an example embodiment of this subject matter. The system 100 and / or detection system 140 disclosed herein can be implemented on any suitable vehicle, including but not limited to aircraft such as fixed-wing aircraft, helicopters, or unmanned vehicles or drones. In this respect, system 100 can be the electrical system of an aircraft. Detection system 140 can be located on the aircraft for active component monitoring, or it can be located off-air (e.g., in a laboratory for component testing) or in a service / maintenance shop for off-wing or wing-mounted inspection. Furthermore, the system 100 and / or detection system 140 disclosed herein can be implemented on automobiles, ships, vessels, submarines, trains, hovercraft (not shown), tanks (not shown), and other types of vehicles. Moreover, the inventive aspects of this disclosure can be implemented in or used in non-vehicle applications, such as land-based power generation applications, testing laboratories, and other applications.

[0084] The disclosed detection techniques can provide certain advantages, benefits, and / or technical effects. For example, the disclosed detection techniques can allow the detection of discharge activity without signal loss over a wide frequency bandwidth. Furthermore, partial discharge signals hidden in noise (e.g., transient current responses or current clusters) can be detected more easily. In addition to determining the presence of partial discharge, various characteristics of the detected partial discharge signal can be determined, such as the pulse shape, pulse amplitude, and / or frequency associated with the partial discharge signal. The disclosed techniques can allow the detection of partial discharge initiation voltages and partial discharge extinction voltages.

[0085] The techniques discussed herein refer to computer-based systems and the actions taken by and from computer-based systems, as well as the information sent to and from computer-based systems. Those skilled in the art will recognize that the inherent flexibility of computer-based systems allows for a wide variety of possible configurations, combinations, and divisions of tasks and functions among components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, storage, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0086] While specific features of various embodiments may be shown in some figures but not others, this is merely for convenience. Any feature of the figures may be referenced and / or claimed in conjunction with any feature of any other figure, in accordance with the principles of this disclosure.

[0087] This written description uses examples to disclose this disclosure, including best practices, and also enables any person skilled in the art to practice this disclosure, including making and using any apparatus or system and performing any combination of methods. The patent scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0088] Further aspects are provided by the following topics:

[0089] 1. A method for detecting partial discharge in a power system having a power electronic converter, the method comprising: capturing a first current signal in response to a first applied voltage; capturing a second current signal in response to a second applied voltage, the second applied voltage being different from the first applied voltage; setting the first current signal as a reference signal; determining a difference signal based at least in part on the second current signal and the reference signal; and determining whether a partial discharge exists based at least in part on the difference signal.

[0090] 2. The method according to any one of the preceding clauses, wherein the method is iterated at least once, and wherein each time the method is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the method, the difference signal is determined as the difference between a current current signal captured in response to a currently applied voltage and a previously captured current signal captured in response to a previously applied voltage.

[0091] 3. The method according to any one of the preceding clauses, wherein each time the method is iterated, the currently applied voltage is greater than the previously applied voltage.

[0092] 4. The method according to any one of the preceding clauses, wherein the first applied voltage is greater than the partial discharge initiation voltage, and wherein each time the method is iterated, the currently applied voltage is reduced from the previously applied voltage.

[0093] 5. The method according to any one of the preceding clauses, wherein the difference signal is determined by subtracting a reference signal from the second current signal to determine the difference signal.

[0094] 6. The method according to any one of the preceding clauses, wherein the difference signal is determined by: multiplying the reference signal by a correction factor, the correction factor being expressed as a quotient defined by dividing the second applied voltage by the first applied voltage; and subtracting the product of the reference signal and the correction factor from the second current signal.

[0095] 7. The method according to any one of the preceding clauses, wherein when the difference signal exceeds a threshold, it is determined that partial discharge exists, and wherein when the difference signal does not exceed the threshold, it is determined that partial discharge does not exist.

[0096] 8. The method according to any one of the preceding clauses, wherein the threshold is set at or within a margin of the expected current amplitude, the expected current amplitude being determined as the expected amplitude of the difference signal at the switching edge of the pulse of the second applied voltage, the expected amplitude being determined at least in part based on the voltage increment between the second applied voltage and the first applied voltage.

[0097] 9. The method according to any one of the preceding clauses, wherein the method is iterated at least once, and wherein each time the method is iterated, the method comprises: capturing a current current signal in response to a currently applied voltage, the currently applied voltage being different from a previously applied voltage; setting a previous current signal as the reference signal, the previous current signal being captured in response to the previously applied voltage; determining a difference signal based at least in part on the current current signal and the reference signal; and determining, at least in part on the difference signal, whether a partial discharge exists.

[0098] 10. The method according to any one of the preceding clauses, wherein each time the method is iterated, the currently applied voltage is greater than the previously applied voltage by a predetermined voltage increment, the predetermined voltage increment being fixed between iterations.

[0099] 10a The method according to any one of the preceding clauses further includes: performing a control action in response to detecting a partial discharge in the power system.

[0100] 11. A system comprising: a voltage source; a power converter electrically connected to the voltage source, the power converter having a plurality of switching devices; a load electrically connected to the power converter; and a detection system having a current sensor and a signal analyzer, the signal analyzer having one or more processors configured to implement a detection sequence, wherein, when implementing the detection sequence, the one or more processors are configured to: receive a first current signal captured in response to switching a first voltage applied by the plurality of switching devices; receive a second current signal captured in response to switching a second voltage applied by the plurality of switching devices, the second voltage being different from the first voltage; set the first current signal as a reference signal; determine a difference signal based at least in part on the second current signal and the reference signal; and determine the presence of partial discharge based at least in part on the difference signal.

[0101] 12. The system according to any one of the preceding clauses, wherein the detection sequence is iterated at least once, and wherein each time the detection sequence is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the detection sequence, the difference signal is determined as the difference between a current current signal captured in response to a currently applied voltage and a previously captured current signal captured in response to a previously applied voltage.

[0102] 13. The system according to any one of the preceding clauses, wherein each time the detection sequence is iterated, the currently applied voltage is greater than the previously applied voltage.

[0103] 14. The system according to any one of the preceding clauses, wherein the first applied voltage is greater than the partial discharge initiation voltage, and wherein each time the detection sequence is iterated, the currently applied voltage is reduced from the previously applied voltage.

[0104] 15. The system according to any one of the preceding clauses, wherein when the difference signal exceeds a threshold, it is determined that a partial discharge exists, and wherein when the difference signal does not exceed the threshold, it is determined that no partial discharge exists.

[0105] 16. The system according to any one of the preceding clauses, wherein the threshold is set at or within a margin of a expected current amplitude, the expected current amplitude being determined as the expected amplitude of the difference signal at the switching edge of the pulse of the second voltage, the expected amplitude being determined at least in part based on the voltage increment between the second voltage and the first voltage.

[0106] 17. A non-transitory computer-readable medium comprising computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform a detection sequence, wherein, when performing the detection sequence, the one or more processors are configured to: receive a first current signal captured in response to a first applied voltage; receive a second current signal captured in response to a second applied voltage, the second applied voltage being different from the first applied voltage; set the first current signal as a reference signal; determine a difference signal based at least in part on the second current signal and the reference signal; and determine, at least in part on the difference signal, whether a partial discharge exists.

[0107] 18. A non-transitory computer-readable medium according to any one of the preceding clauses, wherein the detection sequence is iterated at least once, and wherein each time the detection sequence is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the detection sequence, the difference signal is determined as the difference between a current current signal captured in response to a currently applied voltage and a previously captured current signal captured in response to a previously applied voltage.

[0108] 19. The non-transitory computer-readable medium according to any one of the preceding clauses, wherein each time the detection sequence is iterated, the currently applied voltage is greater than the previously applied voltage.

[0109] 20. The non-transitory computer-readable medium according to any one of the preceding clauses, wherein when the difference signal exceeds a threshold, a partial discharge is determined to exist, and wherein when the difference signal does not exceed the threshold, a partial discharge is determined not to exist.

Claims

1. A method for detecting partial discharge in a power system with a power electronic converter, characterized in that, The method includes: In response to a first applied voltage, a first current signal is captured; In response to a second applied voltage, a second current signal is captured, wherein the second applied voltage is different from the first applied voltage; Set the first current signal as the reference signal; The difference signal is determined at least in part based on the second current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal. The method is iterated at least once, and each time the method is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the method, the difference signal is determined as the difference between the current current signal captured in response to the currently applied voltage and the previously captured current signal captured in response to the previously applied voltage.

2. The method according to claim 1, characterized in that, Each time the method is iterated, the currently applied voltage is greater than the previously applied voltage.

3. The method according to claim 1, characterized in that, The first applied voltage is greater than the partial discharge initiation voltage, and each time the method is iterated, the currently applied voltage is reduced from the previously applied voltage.

4. The method according to claim 1, characterized in that, The difference signal is determined by subtracting the reference signal from the second current signal to determine the difference value.

5. The method according to claim 1, characterized in that, The difference signal is determined by the following: The reference signal is multiplied by a correction factor, which is expressed as the quotient defined by dividing the second applied voltage by the first applied voltage; and Subtract the product of the reference signal and the correction coefficient from the second current signal.

6. The method according to claim 1, characterized in that, When the difference signal exceeds a threshold, partial discharge is determined to exist; when the difference signal does not exceed the threshold, partial discharge is determined to not exist.

7. The method according to claim 6, characterized in that, The threshold is set at or within a margin of the expected current amplitude, which is determined as the expected amplitude of the difference signal at the switching edge of the pulse of the second applied voltage, and the expected amplitude is determined at least in part based on the voltage increment between the second applied voltage and the first applied voltage.

8. The method according to claim 1, characterized in that, The method is iterated at least once, and each time the method is iterated, the method includes: The system captures a current current signal in response to a currently applied voltage, which is different from a previously applied voltage. The previous current signal is set as the reference signal, the previous current signal being captured in response to the previously applied voltage; The difference signal is determined at least in part based on the current current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal.

9. The method according to claim 8, characterized in that, Each time the method is iterated, the currently applied voltage is larger than the previously applied voltage by a predetermined voltage increment, and the predetermined voltage increment is fixed between iterations.

10. A system, characterized in that, include: Voltage source; A power converter, which is electrically connected to the voltage source, and the power converter has multiple switching devices; A load, which is electrically connected to the power converter; and A detection system comprising a current sensor and a signal analyzer, the signal analyzer having one or more processors configured to implement a detection sequence, wherein, when implementing the detection sequence, the one or more processors are configured to: Receive a first current signal captured in response to a first voltage applied by switching the plurality of switching devices; Receive a second current signal captured in response to a second voltage applied by switching the plurality of switching devices, the second voltage being different from the first voltage; Set the first current signal as the reference signal; The difference signal is determined at least in part based on the second current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal. The detection sequence is iterated at least once, and each time the detection sequence is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the detection sequence, the difference signal is determined as the difference between the current current signal captured in response to the currently applied voltage and the previously captured current signal captured in response to the previously applied voltage.

11. The system according to claim 10, characterized in that, Each time the detection sequence is iterated, the currently applied voltage is greater than the previously applied voltage.

12. The system according to claim 10, characterized in that, The applied first voltage is greater than the partial discharge initiation voltage, and the currently applied voltage is reduced from the previously applied voltage each time the detection sequence is iterated.

13. The system according to claim 10, characterized in that, When the difference signal exceeds a threshold, partial discharge is determined to exist; when the difference signal does not exceed the threshold, partial discharge is determined to not exist.

14. The system according to claim 13, characterized in that, The threshold is set at or within a margin of the expected current amplitude, which is determined as the expected amplitude of the difference signal at the switching edge of the pulse of the second voltage, and the expected amplitude is determined at least in part based on the voltage increment between the second voltage and the first voltage.

15. A non-transitory computer-readable medium comprising computer-executable instructions, which, when executed by one or more processors, cause the one or more processors to perform a detection sequence, characterized in that, When implementing the detection sequence, the one or more processors are configured to: Receive a first current signal captured in response to a first applied voltage; Receive a second current signal captured in response to a second applied voltage, wherein the second applied voltage is different from the first applied voltage; Set the first current signal as the reference signal; The difference signal is determined at least in part based on the second current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal. The detection sequence is iterated at least once, and each time the detection sequence is iterated, the reference signal is updated on a rolling basis to a previously captured current signal, such that for a given iteration of the detection sequence, the difference signal is determined as the difference between the current current signal captured in response to the currently applied voltage and the previously captured current signal captured in response to the previously applied voltage.

16. The non-transitory computer-readable medium according to claim 15, characterized in that, Each time the detection sequence is iterated, the currently applied voltage is greater than the previously applied voltage.

17. The non-transitory computer-readable medium according to claim 15, characterized in that, When the difference signal exceeds a threshold, partial discharge is determined to exist; when the difference signal does not exceed the threshold, partial discharge is determined to not exist.

18. A method for detecting partial discharge in a power system with a power electronic converter, characterized in that, The method includes: In response to a first applied voltage, a first current signal is captured; In response to a second applied voltage, a second current signal is captured, wherein the second applied voltage is different from the first applied voltage; Set the first current signal as the reference signal; The difference signal is determined at least in part based on the second current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal. When the difference signal exceeds a threshold, partial discharge is determined to exist; when the difference signal does not exceed the threshold, partial discharge is determined to not exist. The threshold is set at or within a margin of the expected current amplitude, which is determined as the expected amplitude of the difference signal at the switching edge of the pulse of the second applied voltage, and the expected amplitude is determined at least in part based on the voltage increment between the second applied voltage and the first applied voltage.

19. A method for detecting partial discharge in a power system with a power electronic converter, characterized in that, The method includes: In response to a first applied voltage, a first current signal is captured; In response to a second applied voltage, a second current signal is captured, wherein the second applied voltage is different from the first applied voltage; Set the first current signal as the reference signal; The difference signal is determined at least in part based on the second current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal. The method is iterated at least once, and each time the method is iterated, the method includes: The system captures a current current signal in response to a currently applied voltage, which is different from a previously applied voltage. The previous current signal is set as the reference signal, the previous current signal being captured in response to the previously applied voltage; The difference signal is determined at least in part based on the current current signal and the reference signal; and The presence of partial discharge is determined, at least in part, based on the difference signal.

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