Hybrid high-voltage direct-current circuit breaker energy consumption branch fault detection method and device

Abstract

The invention provides a hybrid high-voltage direct-current circuit breaker energy consumption branch fault detection method and device, and can be applied to the technical field of flexible direct-current systems. The method comprises the steps that the current of the upper half branch / the lower half branch of the mth energy consumption branch of the hybrid high-voltage direct-current circuit breaker is obtained, and m is a positive integer; performing normalization and first-order difference calculation on the current in sequence to obtain an analysis current; decomposing the analysis current by using empirical Fourier decomposition to obtain a fault feature component; determining a sudden change peak value according to the fault feature component; and determining the fault state of the hybrid high-voltage direct-current circuit breaker energy consumption branch according to the sudden change peak value. According to the hybrid high-voltage direct-current circuit breaker energy consumption branch fault detection method and device provided by the invention, the fault detection of the hybrid high-voltage direct-current circuit breaker energy consumption branch can be more accurate.

Description

Technical Field

[0001] The present application relates to the technical field of flexible direct current systems, and in particular to a method and device for detecting faults in energy-consuming branches of a hybrid high-voltage direct current circuit breaker. Background Art

[0002] Due to the urgent need for access to a large number of renewable energy sources, flexible DC systems have been further developed, among which multi-terminal flexible high-voltage DC systems have received great attention and research, and have also promoted the development of multi-terminal flexible DC distribution systems. However, due to the relatively low impedance and low current tolerance of these systems, when a fault occurs, a DC circuit breaker is needed to quickly remove the fault to ensure its own reliability and stability.

[0003] As far as the mainstream design route of hybrid high-voltage DC circuit breakers is concerned, no matter what topology of hybrid high-voltage DC circuit breakers, it requires an energy-consuming branch, which is composed of metal oxide varistors (MOVs). Its function is to dissipate the energy stored in the DC grid, and at the same time, use the residual voltage characteristics of MOVs to protect other circuits such as transfer branches in the circuit breaker. On the other hand, due to the high voltage level and large transmission capacity of the flexible DC grid, its operation and control protection methods are diverse. For example, in a certain project, the absorption energy of the hybrid high-voltage DC circuit breaker MOV is as high as 150MJ, and the energy absorption time of MOV is relatively long, up to 50ms. Therefore, the application conditions of the hybrid high-voltage DC circuit breaker MOV are closely connected with the flexible DC grid, and the reliability of MOV will directly affect the reliability of the flexible DC grid. Therefore, a corresponding energy-consuming branch fault detection method is required to ensure the operation reliability of the hybrid high-voltage DC circuit breaker.

[0004] However, the current energy consumption branch detection method mainly relies on the differential current between the MOV branch and the main branch for detection, and this differential current is easily affected by signal synchronization and the threshold setting is difficult. Therefore, it is necessary to propose a new energy consumption branch fault detection method to ensure the operation reliability of the hybrid high-voltage DC circuit breaker energy consumption branch. Summary of the invention

[0005] In view of the problems in the prior art, the embodiments of the present application provide a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method and device, which can at least partially solve the problems in the prior art.

[0006] On the one hand, the present application proposes a hybrid high-voltage direct current circuit breaker energy-consuming branch fault detection method, comprising:

[0007] Obtaining the current of the upper half branch / lower half branch of the mth energy consumption branch of the hybrid high-voltage direct current circuit breaker, where m is a positive integer;

[0008] The current is normalized and first-order difference calculated in sequence to obtain an analysis current;

[0009] Decomposing the analysis current by using empirical Fourier decomposition to obtain fault characteristic components;

[0010] Determining a mutation peak value according to the fault characteristic component;

[0011] The fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker is determined according to the sudden change peak value.

[0012] In some embodiments, the step of normalizing and first-order difference calculating the current in sequence to obtain the analysis current includes:

[0013] The time when the current reaches the maximum peak after the energy consumption branch is started is taken as the time starting point, and the current after the time starting point is segmented in sequence according to the preset time intervals, until the current is less than the preset current threshold for the first time, then the segmentation is stopped to obtain k segmented currents, where k is a positive integer;

[0014] According to the k segment currents, normalizing each segment current to obtain a normalized current corresponding to each segment current;

[0015] A first-order difference operation is performed on each of the normalized currents to obtain an analysis current corresponding to each of the normalized currents.

[0016] In some embodiments, the step of decomposing the analysis current using empirical Fourier decomposition to obtain fault characteristic components includes:

[0017] Decomposing each of the analysis currents using empirical Fourier decomposition to obtain different time-frequency components of the analysis current;

[0018] For each of the analysis currents, the highest time-frequency component is selected from the time-frequency components of the analysis current as the fault characteristic component corresponding to the analysis current.

[0019] In some embodiments, determining the mutation peak value according to the fault characteristic component includes:

[0020] For each fault characteristic component of the analysis current, a first-order difference operation is performed on the fault characteristic component and then multiplied by a preset coefficient to obtain a sudden change peak value corresponding to the analysis current.

[0021] In some embodiments, determining the fault state of the energy-consuming branch of the hybrid high-voltage DC circuit breaker according to the sudden change peak value includes:

[0022] According to the order of the acquisition time of the segmented current from first to last, it is judged whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the acquisition current corresponding to each segmented current, and the judgment is stopped until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

[0023] In some embodiments, judging whether the hybrid high-voltage DC circuit breaker energy consumption branch is faulty according to the sudden change peak value corresponding to the collected current corresponding to each segment current in the order of the acquisition time of the segment current from first to last, and stopping judging until the fault state of the hybrid high-voltage DC circuit breaker energy consumption branch is determined, includes:

[0024] Determine whether the mutation peak value corresponding to the analysis current corresponding to the segment current with the first acquisition time is greater than the detection threshold;

[0025] If the sudden change peak value is greater than the detection threshold, it is determined that the energy-consuming branch of the hybrid high-voltage direct current circuit breaker is faulty, and the fault determination is stopped.

[0026] In some embodiments, the method further comprises:

[0027] If the mutation peak value is less than or equal to the detection threshold, determining whether the segment current whose acquisition time ranks last is less than the preset current threshold;

[0028] If the segment current is less than the preset current threshold, it is determined that the energy-consuming branch of the hybrid high-voltage direct current circuit breaker has not failed, and the fault determination is stopped.

[0029] On the other hand, the present application proposes a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device, comprising:

[0030] An acquisition module, used for acquiring the current of the upper half branch / lower half branch of the mth energy consumption branch of the hybrid high-voltage direct current circuit breaker, wherein m is a positive integer;

[0031] A calculation module, used for performing normalization and first-order difference calculation on the current in sequence to obtain an analysis current;

[0032] A decomposition module, used for decomposing the analysis current by using empirical Fourier decomposition to obtain fault characteristic components;

[0033] A first determination module, used to determine a mutation peak value according to the fault characteristic component;

[0034] The second determination module is used to determine the fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker according to the sudden change peak value.

[0035] In some embodiments, the computing module is specifically used for:

[0036] The time when the current reaches the maximum peak after the energy consumption branch is started is taken as the time starting point, and the current after the time starting point is segmented in sequence according to the preset time intervals, until the current is less than the preset current threshold for the first time, then the segmentation is stopped to obtain k segmented currents, where k is a positive integer;

[0037] According to the k segment currents, normalizing each segment current to obtain a normalized current corresponding to each segment current;

[0038] A first-order difference operation is performed on each of the normalized currents to obtain an analysis current corresponding to each of the normalized currents.

[0039] In some embodiments, the decomposition module is specifically used to:

[0040] Decomposing each of the analysis currents using empirical Fourier decomposition to obtain different time-frequency components of the analysis current;

[0041] For each of the analysis currents, the highest time-frequency component is selected from the time-frequency components of the analysis current as the fault characteristic component corresponding to the analysis current.

[0042] In some embodiments, the first determining module is specifically configured to:

[0043] For each fault characteristic component of the analysis current, a first-order difference operation is performed on the fault characteristic component and then multiplied by a preset coefficient to obtain a sudden change peak value corresponding to the analysis current.

[0044] In some embodiments, the second determining module is specifically configured to:

[0045] According to the order of the acquisition time of the segmented current from first to last, it is judged whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the acquisition current corresponding to each segmented current, and the judgment is stopped until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

[0046] In some embodiments, the second determining module is specifically configured to:

[0047] Determine whether the mutation peak value corresponding to the analysis current corresponding to the segment current with the first acquisition time is greater than the detection threshold;

[0048] If the sudden change peak value is greater than the detection threshold, it is determined that the energy-consuming branch of the hybrid high-voltage direct current circuit breaker is faulty, and the fault determination is stopped.

[0049] In some embodiments, the second determining module is further configured to:

[0050] If the mutation peak value is less than or equal to the detection threshold, determining whether the segment current whose acquisition time ranks last is less than the preset current threshold;

[0051] If the segment current is less than the preset current threshold, it is determined that the energy-consuming branch of the hybrid high-voltage direct current circuit breaker has not failed, and the fault determination is stopped.

[0052] An embodiment of the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the hybrid high-voltage direct current circuit breaker energy-consuming branch fault detection method described in any of the above embodiments are implemented.

[0053] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the hybrid high-voltage direct current circuit breaker energy-consuming branch fault detection method described in any of the above embodiments are implemented.

[0054] The hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method and device provided in the embodiment of the present application obtains the current of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker, where m is a positive integer; normalizes and first-order difference calculations are performed on the current in sequence to obtain an analysis current; decomposes the analysis current using empirical Fourier decomposition to obtain a fault characteristic component; determines a mutation peak value based on the fault characteristic component; and determines the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch based on the mutation peak value. In this way, the fault detection of the hybrid high-voltage DC circuit breaker energy-consuming branch is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0056] Figure 1 It is a topological diagram of a hybrid high-voltage DC circuit breaker.

[0057] Figure 2 It is a flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in an embodiment of the present application.

[0058] Figure 3 It is a partial flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in one embodiment of the present application.

[0059] Figure 4 It is a partial flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in one embodiment of the present application.

[0060] Figure 5 It is a partial flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in one embodiment of the present application.

[0061] Figure 6 It is a partial flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in one embodiment of the present application.

[0062] Figure 7 It is a partial flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in one embodiment of the present application.

[0063] Figure 8 It is a flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in an embodiment of the present application.

[0064] Fig. 9 This is a topological diagram of a multi-terminal flexible DC system described in an embodiment of the present application.

[0065] Fig.10 It is the fault current breaking waveform of the robust hybrid high-voltage DC circuit breaker described in one embodiment of the present application.

[0066] Fig.11 This is the test waveform diagram of Case A described in the embodiment of the present application.

[0067] Fig.12 This is the test waveform diagram of Case B described in the embodiment of the present application.

[0068] Fig.13 It is a structural schematic diagram of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device provided in one embodiment of the present application.

[0069] Fig.14 It is a schematic diagram of the physical structure of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but are not intended to limit the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be arbitrarily arranged with each other.

[0071] The terms “first”, “second”, etc. used in this document do not specifically refer to an order or sequence, nor are they used to limit this application. They are only used to distinguish elements or operations described with the same technical terms.

[0072] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0073] As used herein, "and / or" includes any and all permutations of the items described.

[0074] In order to better understand the present application, the research background of the present application is first introduced in detail below.

[0075] (I) Breaking principle of hybrid high-voltage DC circuit breaker

[0076] Figure 1 This is a topological diagram of a hybrid high-voltage DC circuit breaker. Figure 1 In the figure, the hybrid high-voltage DC circuit breaker includes three branches: main branch, transfer branch and energy consumption branch, m is the power electronic switch submodule number and the energy consumption branch submodule number. The main branch is the main branch transfer switch, fast mechanical switch and main branch stray inductance L z The transfer branch is composed of multiple power electronic switch submodules connected in series. Taking the mth power electronic switch module as an example, the submodule consists of a diode, a power electronic insulated gate bipolar transistor (IGBT), a buffer capacitor C m1 , stray inductance L m1 and L m2 , and the snubber resistor R m1 and R m2 It is used for fault current transfer and transient voltage establishment; the energy consumption branch is connected in parallel with the power electronic switch module, which is composed of multiple metal oxide varistors (Metal-oxide varistor, MOV) in series and parallel and stray inductance L m3 composition to achieve energy dissipation.

[0077] The working principle of the hybrid high-voltage DC circuit breaker is as follows:

[0078] 1) When the system is at t 0 After a short circuit occurs, the fault current i br Rapidly increases, at this time, the main branch continues to conduct current, the main branch current i ma Equal to i br .

[0079] 2) After a certain system side protection method detection time interval, the circuit breaker is at t a When receiving the disconnection command, the main branch transfer switch is locked, i ma starts to decrease until time t b ,i ma decreases to zero, during which i br Continue to increase.

[0080] 3) After the main branch current is zero, the fast mechanical switch begins to open, and the IGBT of the transfer branch is turned on. br The current is commutated to the transfer branch, and the transfer branch current i tr Equal to i br .

[0081] 4) Fast mechanical switch break at t c Keep enough insulation distance at all times. At this time, turn off the IGBT in the transfer branch. br A transient voltage will be established through the buffer capacitor. When the transient voltage exceeds the starting voltage of the energy-consuming branch MOV, i br The flow will flow from the transfer branch to the energy consumption branch, i tr starts to decrease. At t d Moment, i tr decrease to zero;

[0082] 5) When the energy-consuming branch MOV is turned on, the circuit breaker enters the energy-consuming stage, and the MOV begins to absorb energy. br starts to decrease until t e Moment, i br The energy consumption branch current i mo Equal to i br .

[0083] (II) Principle of Empirical Fourier Decomposition

[0084] Empirical Fourier Decomposition (EFD) includes two key steps: improved segmentation technology and zero-phase filter bank construction technology.

[0085] 2.1 Improved segmentation technology

[0086] In the improved segmentation technique, the frequency range [0, π] is divided into M consecutive frequency segments. Unlike the local maximum and minimum techniques, the frequency ω 0 and frequency ω Nare not necessarily equal to 0 and π, respectively; their values ​​are determined during the adaptive sorting process. During the sorting process, the Fourier spectrum amplitudes at frequencies ω = 0 and ω = π and their local maxima are identified and extracted into a sequence. All amplitudes in the sequence are sorted in descending order. The frequencies corresponding to the first M maxima in the sorted sequence are denoted by [Ω 1 ,Ω 2 , ..., Ω M ] indicates. In addition, the left boundary frequency Ω is also defined 0 =0 and right boundary frequency Ω M+1 =π. The boundary of each line segment is determined by the following equation (1).

[0087]

[0088] In the formula, X i (ω) indicates the frequency in Ω m and Ω m+1 The amplitude of the Fourier spectrum between , i is the frequency band number.

[0089] 2.2 Zero-phase filter construction technology

[0090] In EFD, the zero-phase filter bank is constructed based on the frequency bands obtained by the improved segmentation technique. In each frequency band, the zero-phase filter is a bandpass filter with a cutoff frequency of ω n-1 and ω n , and there is no transition phase. Therefore, the zero-phase filter retains the main Fourier spectrum components in the segment and excludes all other Fourier spectrum components outside the segment.

[0091] First, the Fourier transform of a signal f(t) See formula (2).

[0092]

[0093] The zero-phase filter can be To construct, as shown in formula (3).

[0094]

[0095] Where, frequency ω n The value of is determined by formula (1).

[0096] After obtaining the zero-phase filter bank, Perform the filter operation shown in formula (4) to obtain the filtered frequency domain signal f n (ω).

[0097]

[0098] Performing the inverse Fourier transform of the filtered frequency domain signal in equation (5) can obtain the corresponding time-frequency component f in the time domain. n (t).

[0099]

[0100] 2.3 Empirical Fourier Decomposition Steps

[0101] With the improved segmentation technology and zero-phase filter bank construction technology, the specific steps of empirical Fourier decomposition are as follows:

[0102] Step a: Analyze the signal Perform fast Fourier transform to obtain its complex coefficients And get its Fourier spectrum Wherein, m is the number of the energy consumption branch of the hybrid high-voltage DC circuit breaker; λ is the signal segment number; It is based on the upper / lower branch MOV device current I of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker m-L (t) is obtained, and the specific calculation method can be found in the specific embodiments of the present application below.

[0103] Step b: Set the number of empirical Fourier decomposition layers to n, and use the improved spectrum segmentation technique to determine The spectrum boundary ω n .

[0104] Step c: Based on the obtained spectrum boundary ω n , construct a zero-phase filter bank

[0105] Step d: Utilization Get the frequency domain components after filtering

[0106] Step e: Perform inverse Fourier transform to obtain the time-frequency components

[0107] In this application, in order to include enough high-frequency component information as much as possible, the decomposition level n can be selected as 3, and the highest frequency component is the fault characteristic component.

[0108] The execution subject of the hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in the embodiment of the present application includes but is not limited to a computer.

[0109] Figure 2 FIG. 1 is a flow chart of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in an embodiment of the present application, such as Figure 2As shown, the hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in the embodiment of the present application includes:

[0110] S101, obtaining a current of an upper half branch / lower half branch of an mth energy-consuming branch of a hybrid high-voltage direct current circuit breaker, where m is a positive integer;

[0111] In step S101, Figure 3 As shown, the hybrid high-voltage DC circuit breaker includes at least two energy-consuming branches, and the mth energy-consuming branch can be any energy-consuming branch of the hybrid high-voltage DC circuit breaker; each of the energy-consuming branches includes an upper half branch and a lower half branch.

[0112] When fault monitoring is performed on the energy-consuming branch of the hybrid high-voltage DC circuit breaker, the current of the upper half branch / lower half branch of one of the energy-consuming branches can be obtained, and then the fault detection of the energy-consuming branch of the hybrid high-voltage DC circuit breaker is performed according to the current.

[0113] S102, performing normalization and first-order difference calculation on the current in sequence to obtain an analysis current;

[0114] In step S102, the current is first normalized, and then a first-order difference calculation is performed on the normalized result to obtain the analysis current.

[0115] S103, decomposing the analysis current by using empirical Fourier decomposition to obtain fault characteristic components;

[0116] In step S102, each analysis current is decomposed by using empirical Fourier decomposition to obtain different time-frequency components of the analysis current, and a time-frequency component is selected from the time-frequency components as the fault characteristic component.

[0117] S104, determining a mutation peak value according to the fault characteristic component;

[0118] In step S104, a mutation peak is calculated according to the fault characteristic component.

[0119] S105. Determine the fault state of the energy-consuming branch of the hybrid high-voltage DC circuit breaker according to the sudden change peak value.

[0120] In step S105, after obtaining the sudden change peak value, the fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker is determined using the sudden change peak value, for example, whether the energy-consuming branch is faulty or not.

[0121] The hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided by the present application obtains the current of the upper half branch / lower half branch of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker, where m is a positive integer; normalizes and first-order difference calculations are performed on the current in sequence to obtain an analysis current; decomposes the analysis current using empirical Fourier decomposition to obtain a fault characteristic component; determines a mutation peak value based on the fault characteristic component; and determines the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch based on the mutation peak value. In this way, the fault detection of the hybrid high-voltage DC circuit breaker energy-consuming branch is more accurate.

[0122] like Figure 4 As shown, in some embodiments, the normalizing and first-order difference calculation are performed on the current in sequence to obtain the analysis current, including:

[0123] S1021, taking the time when the current reaches the maximum peak after the energy consumption branch is started as the time starting point, segmenting the current after the time starting point in chronological order according to preset time intervals until the current is less than a preset current threshold for the first time, then stopping segmenting, and obtaining k segmented currents, where k is a positive integer;

[0124] S1022. According to the k segment currents, normalize each segment current to obtain a normalized current corresponding to each segment current;

[0125] S1023. Perform a first-order difference operation on each of the normalized currents to obtain an analysis current corresponding to each of the normalized currents.

[0126] Specifically, in step 1, for the current I of the upper branch / lower branch of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker, m-L (t). Im-L(t) is segmented and the segmented currents are numbered starting from 1. The breaking current with segment number λ is expressed as For the λth segment current The starting time is t st and the termination time is t en ; where t p is the time when the current value reaches the peak value after the energy consumption branch is started, and ΔT is a preset time interval. In this application, ΔT can be taken as 3ms;

[0127]

[0128] Step 2: Determine Is it less than a preset current threshold, which can be 10A? If so, then based on the time when the preset current threshold appears, After the signal length is padded to 1 ΔT, proceed to step 3; if not, proceed directly to step 3;

[0129] Step 3: For each Perform normalization operation to obtain the The corresponding normalized current Among them, g max and g min Represent the maximum and minimum values ​​of the normalized signal, taking 1 and 0 respectively. express The minimum value of express The maximum value of

[0130]

[0131] Step 4: For each Perform a first-order difference operation to obtain the Corresponding analysis current

[0132]

[0133] like Figure 5 As shown, in some embodiments, the method of decomposing the analysis current by using empirical Fourier decomposition to obtain fault characteristic components includes:

[0134] S1031, decomposing each of the analysis currents by using empirical Fourier decomposition to obtain different time-frequency components of the analysis current;

[0135] S1032. For each analysis current, select the highest time-frequency component among the time-frequency components of the analysis current as the fault characteristic component corresponding to the analysis current.

[0136] Specifically, for each analysis current Perform 3-layer empirical Fourier decomposition and select the highest frequency time-frequency component As the analysis current The corresponding fault feature component.

[0137] In some embodiments, determining the mutation peak value according to the fault characteristic component includes: for each fault characteristic component of the analysis current, performing a first-order difference operation on the fault characteristic component and multiplying the result by a preset coefficient to obtain the mutation peak value corresponding to the analysis current.

[0138] Specifically, according to the fault characteristic component Calculate mutation peak The formula is as follows:

[0139]

[0140] In some embodiments, determining the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch according to the sudden change peak value includes: judging whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the collected current corresponding to each segmented current in order of the acquisition time of the segmented current from first to last, and stopping the judgment until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

[0141] like Figure 6 As shown, in some embodiments, judging whether the hybrid high-voltage DC circuit breaker energy consumption branch is faulty according to the sudden change peak value corresponding to the collected current corresponding to each segment current in the order of the acquisition time of the segment current from first to last, until the fault state of the hybrid high-voltage DC circuit breaker energy consumption branch is determined, then stopping the judgment includes:

[0142] S1051, determining whether the mutation peak value corresponding to the analysis current corresponding to the segment current whose acquisition time ranks first is greater than the detection threshold;

[0143] S1052: If the sudden change peak value is greater than the detection threshold, it is determined that the energy-consuming branch of the hybrid high-voltage DC circuit breaker is faulty, and fault determination is stopped.

[0144] like Figure 7 As shown, in the above embodiment, the method may further include:

[0145] S1053, if the mutation peak value is less than or equal to the detection threshold, determining whether the segment current whose acquisition time ranks last is less than the preset current threshold;

[0146] S1054: If the segment current is less than the preset current threshold, it is determined that the energy-consuming branch of the hybrid high-voltage DC circuit breaker has not failed, and the fault determination is stopped.

[0147] For a better understanding of the present application, the hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided by the present application is described in detail below through a specific embodiment.

[0148] like Figure 8 As shown, the hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method provided in this embodiment includes:

[0149] Step 1: Obtain the lower half branch current I of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker m-L (t); In this step, the mth energy consumption branch is set to include the MOV of the upper branch and the lower branch.

[0150] Step 2: I m-L(t) is segmented and the segmented current is numbered starting from 1. The breaking current with segment number λ is expressed as in, The starting time is t st and the termination time is t en ; where t p is the time to reach the peak value after the energy consumption branch is started, ΔT is the time interval, and in this application, ΔT is taken as 3ms;

[0151]

[0152] Step 3: Determination Is it less than 10A? If so, take the time when 10A appears as the benchmark. After the signal length of (t) is padded to 1 ΔT, proceed to step 4; if not, proceed directly to step 4;

[0153] Step 4: Perform normalization operation to obtain the normalized current Among them, g max and g min Respectively represent the maximum and minimum values ​​of the normalized signal, express The minimum value of express The maximum value of

[0154]

[0155] Step 5: Perform first-order difference calculation to obtain the analysis current

[0156]

[0157] Step 6: Perform 3-layer empirical Fourier decomposition and select the highest frequency time-frequency component As fault characteristic component;

[0158] Step 7: Fault characteristic components Mutation peak calculate;

[0159]

[0160] Step 8: Judgment Is it greater than the detection threshold ξ? If so, it is determined that the energy consumption branch is faulty and the detection procedure is terminated; if not, it proceeds to step nine;

[0161] Step 9: Determination Is it less than 10A? If so, it is determined that the energy consumption branch has not failed and the detection procedure is terminated; if not, λ=λ+1 is set and the above steps 3 to 8 are repeated.

[0162] For example, Figure 1 Taking the hybrid high-voltage DC circuit breaker shown in FIG. 1 as an example, its specific parameters are shown in Table 1.

[0163] Table 1 Parameters of hybrid high-voltage DC circuit breaker

[0164] parameter value parameter value <![CDATA[Rated voltage (U rate ) \ kV]]> 535 <![CDATA[Main branch stray inductance (L z ) μH]]> 22.5 <![CDATA[Action time (t FMS )\ ms]]> 3 <![CDATA[Stray inductance of the transfer branch (L m1 ) μH]]> 3 <![CDATA[Residual current (I res ) / A]]> 5 <![CDATA[Stray inductance of the transfer branch (L m2 ) μH]]> 2.1 Number of submodules (m) 10 <![CDATA[Transfer branch resistance (R m1 ) \Ω]]> 16 <![CDATA[MOV number of rows (N p1 )]]> 5 <![CDATA[Transfer branch resistance (R m2 ) \MΩ]]> 3 <![CDATA[MOV number of rows (N p2 )]]> 4 <![CDATA[Transfer branch capacitance (C m1 ) μF]]> 23.3 <![CDATA[MOV number of columns (N s )]]> 12 <![CDATA[Stray inductance of the energy-consuming branch (L m3 ) μH]]> 1

[0165] The hybrid high-voltage DC circuit breaker can be assumed to Fig. 9 In the line Line3 of the multi-terminal flexible DC grid shown in FIG. 1 , the parameters of the multi-terminal flexible DC grid are shown in Table 2.

[0166] Table 2 Multi-terminal flexible DC grid parameters

[0167]

[0168]

[0169] The output power of each converter station is 1pu. The line with short-circuit fault on the system side is Line 3. The fault time is 0ms, which means that the system has been running stably before the fault occurs. The short-circuit fault type is positive grounding short-circuit fault. The fault point is close to the converter station MMC. 3 The distance between them is 109km and the grounding resistance is 0.01Ω. In addition, in order to test the large current breaking, the system side protection time is set to 4ms and the circuit breaker transfer branch shutdown delay is 3ms.

[0170] Under the operating conditions of the system, the fault current breaking waveform of the sound hybrid high-voltage DC circuit breaker is shown in Fig.10 .exist Fig.10 In the circuit breaker, the current flowing through the circuit breaker is composed of the main branch current i ma , transfer branch current i tr and energy consumption branch current i mo Composition, i mo The peak value is about 7kA. In addition, the current sampling frequency is 10kHz.

[0171] Under the above system operating conditions, two energy-consuming branch operation cases were selected to test the proposed method. Case A is normal disconnection, that is, the energy-consuming branch does not have a MOV fault disconnection; Case B is a MOV fault disconnection, and the MOV fault location is a MOV fault in the upper half of the first submodule of the energy-consuming branch, and the fault time is 23ms after the short-circuit fault occurs in the system. Based on these operating conditions and the method proposed in this paper, Fig.11 and Fig.12The relevant waveform diagrams of Case A and Case B during the detection process are given respectively.

[0172] exist Fig.11 In the figure, (a) is the lower half branch current I of the first submodule of the energy consumption branch. 1-L (t), (b) are the analysis current G 1-L (t), (c) are fault characteristic components f 1-3 (t). Fig.11 It can be seen that when λ is 6, the fault characteristic component will increase to a certain extent, which is caused by the nonlinear characteristics of MOV, but from the perspective of its amplitude, its amplitude is only 3×10 -4 . Then, using (c), we can obtain 6 mutation peaks: as well as Their values ​​are 3.4×10 -8 , 1.5×10 -7 , 1.5×10 -7 , 2.0×10 -7 , 3.8×10 -8 , and 1.6×10 -4 These values ​​are all smaller than the detection threshold ζ set in this paper, so I 1-L (t) No sudden change component appears, and it is determined that the energy-consuming branch submodule is in normal breaking condition, which is consistent with the actual setting.

[0173] like Fig.12 As shown, for case B, when the time is 23ms, I 1-L The amplitude of (t) decreases from 0.105kA to 0.0003kA and then decays to 0. This makes G in (b) 1-L The amplitude of (t) is significantly larger than Fig.11 G in (b) 1-L (t). In addition, Fig.12 It can also be found in (c) that f 1-3 The amplitude of (t) also increases, and f 1-3 The time when the maximum value (t) appears coincides with the time when the MOV fault is disconnected, which indicates that the fault characteristic component obtained by EFD can effectively characterize the sudden change component of the original current. Fig.12 (c) and the method proposed in this application, 6 mutation peaks can be calculated: as well as Their values ​​are 3.4×10 -8 , 1.5×10 -7 , 1.5×10 -7 , 2.0×10 -7 , 3.8×10 -8 and 3.9785. Among them, It is much larger than the detection threshold. Therefore, the method provided in this embodiment can accurately determine that the MOV fault disconnection has occurred in the submodule.

[0174] Fig.13 is a structural schematic diagram of a hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device provided in an embodiment of the present application, such as Fig.13 As shown, the hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device provided in the embodiment of the present application includes:

[0175] An acquisition module 21 is used to acquire the current of the upper branch / lower branch of the mth energy consumption branch of the hybrid high-voltage direct current circuit breaker, where m is a positive integer;

[0176] A calculation module 22, used for performing normalization and first-order difference calculation on the current in sequence to obtain an analysis current;

[0177] A decomposition module 23, used to decompose the analysis current by using empirical Fourier decomposition to obtain fault characteristic components;

[0178] A first determination module 24, configured to determine a mutation peak value according to the fault characteristic component;

[0179] The second determination module 25 is used to determine the fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker according to the sudden change peak value.

[0180] The hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device provided by the present application obtains the current of the upper branch / lower branch of the mth energy-consuming branch of the hybrid high-voltage DC circuit breaker, where m is a positive integer; normalizes and first-order difference calculations are performed on the current in sequence to obtain an analysis current; decomposes the analysis current using empirical Fourier decomposition to obtain a fault characteristic component; determines a mutation peak value based on the fault characteristic component; and determines the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch based on the mutation peak value. In this way, the fault detection of the hybrid high-voltage DC circuit breaker energy-consuming branch is more accurate.

[0181] In some embodiments, the computing module is specifically used for:

[0182] The time when the current reaches the maximum peak after the energy consumption branch is started is taken as the time starting point, and the current after the time starting point is segmented in sequence according to the preset time intervals, until the current is less than the preset current threshold for the first time, then the segmentation is stopped to obtain k segmented currents, where k is a positive integer;

[0183] According to the k segment currents, normalizing each segment current to obtain a normalized current corresponding to each segment current;

[0184] A first-order difference operation is performed on each of the normalized currents to obtain an analysis current corresponding to each of the normalized currents.

[0185] In some embodiments, the decomposition module is specifically used to:

[0186] Decomposing each of the analysis currents using empirical Fourier decomposition to obtain different time-frequency components of the analysis current;

[0187] For each of the analysis currents, the highest time-frequency component is selected from the time-frequency components of the analysis current as the fault characteristic component corresponding to the analysis current.

[0188] In some embodiments, the first determining module is specifically configured to:

[0189] For each fault characteristic component of the analysis current, a first-order difference operation is performed on the fault characteristic component and then multiplied by a preset coefficient to obtain a sudden change peak value corresponding to the analysis current.

[0190] In some embodiments, the second determining module is specifically configured to:

[0191] According to the order of the acquisition time of the segmented current from first to last, it is judged whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the acquisition current corresponding to each segmented current, and the judgment is stopped until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

[0192] In some embodiments, the second determining module is specifically configured to:

[0193] Determine whether the mutation peak value corresponding to the analysis current corresponding to the segment current with the first acquisition time is greater than the detection threshold;

[0194] If the sudden change peak value is greater than the detection threshold, the fault of the mth energy-consuming branch of the hybrid high-voltage direct current circuit breaker is determined, and the fault judgment is stopped.

[0195] In some embodiments, the second determining module is further configured to:

[0196] If the mutation peak value is less than or equal to the detection threshold, determining whether the segment current whose acquisition time ranks last is less than the preset current threshold;

[0197] If the segment current is less than the preset current threshold, it is determined that the mth energy-consuming branch of the hybrid high-voltage direct current circuit breaker has not failed, and the fault judgment is stopped.

[0198] The embodiments of the device provided in the embodiments of the present application can be specifically used to execute the processing flow of the above-mentioned method embodiments. Its functions will not be repeated here, and reference can be made to the detailed description of the above-mentioned method embodiments.

[0199] Fig.14 A schematic diagram of the physical structure of an electronic device provided in an embodiment of the present application is shown in FIG. Fig.14 As shown, the electronic device may include: a processor 301, a communication interface 302, a memory 303 and a communication bus 304, wherein the processor 301, the communication interface 302 and the memory 303 communicate with each other through the communication bus 304. The processor 301 may call the logic instructions in the memory 303 to execute the method described in any of the above embodiments.

[0200] In addition, the logic instructions in the above-mentioned memory 303 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art, and the computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk.

[0201] This embodiment discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the methods provided by the above-mentioned method embodiments.

[0202] This embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program enables the computer to execute the methods provided by the above-mentioned method embodiments.

[0203] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0204] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0205] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0206] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0207] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0208] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A hybrid high-voltage DC circuit breaker energy-consuming branch fault detection method, characterized in that: include: Obtaining the current of the upper half branch / lower half branch of the mth energy consumption branch of the hybrid high-voltage direct current circuit breaker, where m is a positive integer; performing normalization and first-order difference calculation on the current in sequence to obtain an analysis current; Decomposing the analysis current by using empirical Fourier decomposition to obtain fault characteristic components; determining a mutation peak value according to the fault characteristic component; The fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker is determined according to the sudden change peak value.

2. The method according to claim 1, characterized in that The normalization and first-order difference calculation are performed on the current in sequence to obtain the analysis current, which includes: The time when the current reaches the maximum peak after the energy consumption branch is started is used as the time starting point, and the current after the time starting point is segmented in chronological order according to preset time intervals until the current is less than the preset current threshold for the first time, then the segmentation is stopped to obtain k segmented currents, where k is a positive integer; According to the k segment currents, normalizing each segment current to obtain a normalized current corresponding to each segment current; A first-order difference operation is performed on each normalized current to obtain an analysis current corresponding to each normalized current.

3. The method according to claim 2, characterized in that The analysis current is decomposed by using empirical Fourier decomposition to obtain fault characteristic components, including: Decomposing each analysis current by using empirical Fourier decomposition to obtain different time-frequency components of the analysis current; For each analysis current, the highest time-frequency component among the time-frequency components of the analysis current is selected as the fault characteristic component corresponding to the analysis current.

4. The method according to claim 3, characterized in that Determining the mutation peak value according to the fault characteristic component includes: For each fault characteristic component of the analysis current, a first-order difference operation is performed on the fault characteristic component and then multiplied by a preset coefficient to obtain a sudden change peak value corresponding to the analysis current.

5. The method according to claim 4, characterized in that Determining the fault state of the energy-consuming branch of the hybrid high-voltage DC circuit breaker according to the sudden change peak value includes: According to the order of the acquisition time of the segmented current from the earliest to the latest, it is judged whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the acquired current corresponding to each segmented current, and the judgment is stopped until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

6. The method according to claim 5, characterized in that The step of determining whether the hybrid HVDC circuit breaker energy consumption branch is faulty according to the sudden change peak value corresponding to the collected current corresponding to each segment current according to the acquisition time of the segment current from earliest to latest, and stopping the determination until the hybrid HVDC circuit breaker energy consumption branch is determined to be in a faulty state comprises: Determine whether the mutation peak value corresponding to the analysis current corresponding to the segment current ranked first in the acquisition time is greater than the detection threshold; If the sudden change peak value is greater than the detection threshold, it is determined that the energy consumption branch of the hybrid high-voltage direct current circuit breaker is faulty, and the fault determination is stopped.

7. The method according to claim 6, characterized in that The method further comprises: If the mutation peak value is less than or equal to the detection threshold, determining whether the current of the segment with the last acquisition time is less than the preset current threshold; If the segment current is less than the preset current threshold, it is determined that no fault occurs in the energy-consuming branch of the hybrid high-voltage direct current circuit breaker, and the fault determination is stopped.

8. A hybrid high-voltage DC circuit breaker energy-consuming branch fault detection device, characterized in that: include: an acquisition module, configured to acquire a current of an upper half branch / lower half branch of an m-th energy-consuming branch of a hybrid high-voltage direct current circuit breaker, wherein m is a positive integer; a calculation module, configured to perform normalization and first-order difference calculation on the current in sequence to obtain an analysis current; a decomposition module, configured to decompose the analysis current using empirical Fourier decomposition to obtain fault characteristic components; A first determining module is used to determine a mutation peak value according to the fault characteristic component; The second determining module is configured to determine a fault state of the energy-consuming branch of the hybrid high-voltage direct current circuit breaker according to the sudden change peak value.

9. The device according to claim 8, characterized in that The calculation module is specifically used for: The time when the current reaches the maximum peak after the energy consumption branch is started is used as the time starting point, and the current after the time starting point is segmented in chronological order according to preset time intervals until the current is less than the preset current threshold for the first time, then the segmentation is stopped to obtain k segmented currents, where k is a positive integer; According to the k segment currents, normalizing each segment current to obtain a normalized current corresponding to each segment current; A first-order difference operation is performed on each normalized current to obtain an analysis current corresponding to each normalized current.

10. The device according to claim 9, characterized in that The decomposition module is specifically used for: Decomposing each analysis current by using empirical Fourier decomposition to obtain different time-frequency components of the analysis current; For each analysis current, the highest time-frequency component among the time-frequency components of the analysis current is selected as the fault characteristic component corresponding to the analysis current.

11. The device according to claim 10, characterized in that The first determining module is specifically configured to: For each fault characteristic component of the analysis current, a first-order difference operation is performed on the fault characteristic component and then multiplied by a preset coefficient to obtain a sudden change peak value corresponding to the analysis current.

12. The device according to claim 11, characterized in that The second determining module is specifically configured to: According to the order of the acquisition time of the segmented current from the earliest to the latest, it is judged whether the hybrid high-voltage DC circuit breaker energy-consuming branch is faulty according to the sudden change peak value corresponding to the acquired current corresponding to each segmented current, and the judgment is stopped until the fault state of the hybrid high-voltage DC circuit breaker energy-consuming branch is determined.

13. The device according to claim 12, characterized in that The second determining module is specifically configured to: Determine whether the mutation peak value corresponding to the analysis current corresponding to the segment current ranked first in the acquisition time is greater than the detection threshold; If the sudden change peak value is greater than the detection threshold, it is determined that the energy consumption branch of the hybrid high-voltage direct current circuit breaker is faulty, and the fault determination is stopped.

14. The device according to claim 13, characterized in that The second determining module is further configured to: If the mutation peak value is less than or equal to the detection threshold, determining whether the current of the segment with the last acquisition time is less than the preset current threshold; If the segment current is less than the preset current threshold, it is determined that no fault occurs in the energy-consuming branch of the hybrid high-voltage direct current circuit breaker, and the fault determination is stopped.

15. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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