A method, system and product for locating fault sections based on transient high-frequency energy

Abstract

The present invention relates to a method, system and product for locating a fault section based on transient high-frequency energy. The method comprises: establishing an active distribution network simulation model in a T-connection form; based on the active distribution network simulation model, monitoring the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point; extracting the M-side fault high-frequency component information according to the M-side fault signal, and extracting the N-side fault high-frequency component information according to the N-side fault component signal; determining the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information; locating the fault position according to the action high-frequency energy and the braking high-frequency energy; the fault position is an in-zone fault on the line or an out-of-zone fault outside the line. For a distribution network to which PV is connected in a T-connection manner, the present invention can locate the fault section using double-end information.

Description

Technical Field

[0001] The present invention relates to the field of fault section positioning in a distribution network, and in particular to a method, system and product for positioning a fault section based on transient high-frequency energy. Background Art

[0002] The fault section location of the distribution network is the prerequisite for fault isolation and self-healing, which is conducive to improving the power supply reliability of the distribution network. The penetration rate of distributed generation (DG) in the distribution network will gradually increase, forming an active distribution network. In order to reduce construction costs and transmission line corridors, the "Technical Guidelines and Preparation Instructions for Distribution Network Planning and Design" points out that DG can be connected to the grid using a T-connection, which changes the fault distribution characteristics. The traditional distribution network fault section location method faces huge challenges.

[0003] Renewable energy generation is mainly divided into photovoltaic power generation and wind power generation. my country's wind energy resources are mainly distributed in the "Three Norths" and the southeast coastal areas, and are mainly connected to the power grid in a large-scale and group-based manner. Therefore, this paper mainly studies the fault location problem after photovoltaic power (PV) is connected to the distribution network in the form of T-connection. For the existing protection of T-connected lines, the current protection scheme mainly adopts a three-terminal longitudinal protection scheme. "Longitudinal protection of T-connected transmission lines of new energy stations based on cosine similarity" comprehensively considers factors such as current transformer saturation, and forms a longitudinal protection scheme by calculating the cosine similarity of the three-terminal current. "Wind power T-connected line protection scheme using voltage amplitude difference and measured impedance characteristics" uses the three-terminal positive sequence voltage and current relationship to propose the main judgment criterion of voltage amplitude difference, and then eliminates the blind spot of the main judgment criterion through adaptive distance auxiliary judgment. "Research on current differential protection of photovoltaic T-connected high-voltage distribution network [J]. Power System Protection and Control" proposes a comprehensive judgment criterion for differential protection of T-connected lines in view of the problem that the differential protection of traditional T-connected lines cannot have both sensitivity and reliability.

[0004] In summary, the existing methods for fault section location and fault distance measurement in distribution networks have made great progress, but further research is still needed for the case where PV is connected to the distribution network in a T-connected manner. The existing fault section location method mainly uses the three-terminal current to form a longitudinal protection, and the fault distance measurement method is mostly for the case of T-connection of the transmission network, and the fault distance is calculated by the three-terminal electrical quantity. However, it is not economical to build a three-terminal fiber channel for distribution networks, and some areas do not have the conditions for building fiber channels. Therefore, for the distribution network where PV is connected in a T-connected manner, it is of great significance to study the method of using two-terminal information to locate the fault section. Summary of the invention

[0005] The purpose of the present invention is to provide a method, system and product for locating a fault section based on transient high-frequency energy, and to locate the fault section of a distribution network to which PV is connected in a T-connection manner by using double-end information.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for locating a fault section based on transient high-frequency energy, comprising:

[0008] Establish a simulation model of active distribution network in T-connection form;

[0009] Based on the active distribution network simulation model, the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point are monitored; the M-side fault signal includes the M-side fault voltage component and the M-side fault current component; the N-side fault signal includes the N-side fault voltage component and the N-side fault current component; M is the bus node; N is the grid connection point when the PV is connected to the grid in a T-connected form;

[0010] Extracting the M-side fault high-frequency component information according to the M-side fault signal, and extracting the N-side fault high-frequency component information according to the N-side fault component signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault component signal includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component;

[0011] Determine the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information;

[0012] The fault position is located according to the action high-frequency energy and the braking high-frequency energy; the fault position is an in-zone fault on the line or an out-of-zone fault outside the line.

[0013] Optionally, extracting the M-side fault high-frequency component information according to the M-side fault signal, and extracting the N-side fault high-frequency component information according to the N-side fault component signal, specifically includes:

[0014] According to the M-side fault signal, a wavelet packet transform method is used to extract the high-frequency component information of the M-side fault;

[0015] According to the N-side fault component signal, the N-side fault high-frequency component information is extracted using a wavelet packet transform method.

[0016] Optionally, the time domain expression of the high-frequency current component of the M-side fault is M (t) is:

[0017] Where, e is 2.7; τ1 is the current decay constant on the back side of M, R MS is the equivalent resistance value of the back side of M; R MN is the resistance value of line MN; α is the fault location parameter;

[0018] The time domain expression of the high-frequency voltage component of the M-side fault is u M (t) is:

[0019] Among them, L MS is the equivalent reactance value of the back side of M; L MN is the reactance value of line MN.

[0020] Optionally, the time domain expression of the high-frequency current component of the N-side fault is M (t) is:

[0021] Where τ2 is the current decay constant on the back side of N, R NX is the equivalent resistance value of the N back side;

[0022] The time domain expression of the high-frequency voltage component of the N-side fault is u N (t) is:

[0023] Among them, R eq is the equivalent resistance value of N back side R NX High frequency resistance R equivalent to photovoltaic power supply PV The parallel result of eq L is the equivalent reactance value of N back side NX High frequency reactance L equivalent to photovoltaic power supply PV The parallel result.

[0024] Optionally, determining the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information specifically includes:

[0025] The product of the M-side fault high-frequency voltage component and the M-side fault high-frequency current component is determined as the M-side transient high-frequency energy;

[0026] The product of the N-side fault high-frequency voltage component and the N-side fault high-frequency current component is determined as the N-side transient high-frequency energy;

[0027] Determine the absolute value of the difference between the M-side transient high-frequency energy and the N-side transient high-frequency energy as the action high-frequency energy;

[0028] The absolute value of the sum of the M-side transient high-frequency energy and the N-side transient high-frequency energy is determined as the braking high-frequency energy.

[0029] Optionally, locating the fault position according to the action high-frequency energy and the braking high-frequency energy specifically includes:

[0030] determining a ratio of the action high-frequency energy to the braking high-frequency energy as a high-frequency energy ratio;

[0031] When the high frequency energy ratio is greater than 1, determining that the fault location is an intra-area fault on the line;

[0032] When the high frequency energy ratio is less than 1, it is determined that the fault location is an out-of-zone fault outside the line.

[0033] A fault section location system based on transient high-frequency energy, comprising:

[0034] Active distribution network simulation model building module, used to build the active distribution network simulation model under T-connection form;

[0035] The M-side fault signal and N-side fault signal monitoring module is used to monitor the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point based on the active distribution network simulation model; the M-side fault signal includes the M-side fault voltage component and the M-side fault current component; the N-side fault signal includes the N-side fault voltage component and the N-side fault current component; M is the bus node; N is the grid connection point when the PV is connected to the grid in a T-connected form;

[0036] An M-side fault high-frequency component information and an N-side fault high-frequency component information extraction module, used to extract the M-side fault high-frequency component information according to the M-side fault signal, and to extract the N-side fault high-frequency component information according to the N-side fault component signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault component signal includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component;

[0037] An action high-frequency energy and a braking high-frequency energy determination module, used to determine the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information;

[0038] The fault location positioning module is used to locate the fault location according to the action high-frequency energy and the braking high-frequency energy; the fault location is an in-zone fault on the line or an out-of-zone fault outside the line.

[0039] Optionally, the M-side fault high-frequency component information and the N-side fault high-frequency component information extraction module specifically include:

[0040] An M-side fault high-frequency component information extraction unit is used to extract the M-side fault high-frequency component information by using a wavelet packet transform method according to the M-side fault signal;

[0041] The N-side fault high-frequency component information extraction unit is used to extract the N-side fault high-frequency component information by using a wavelet packet transform method according to the N-side fault component signal.

[0042] An electronic device includes a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the above-mentioned fault section locating method based on transient high-frequency energy.

[0043] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for locating a fault section based on transient high-frequency energy is implemented.

[0044] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention provides a method, system and product for locating a fault section based on transient high-frequency energy, establishes an active distribution network simulation model in a T-connection form, monitors the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point, and finally determines the action high-frequency energy and the braking high-frequency energy based on the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point to locate the fault position; the present invention can locate the fault position through double-end electrical quantities. Under different fault types, the action high-frequency energy corresponding to the fault section is greater than the braking high-frequency energy. In the face of different types of phase-to-phase fault forms, the protection fault section locating strategy can correctly distinguish between faults inside and outside the zone, indicating that the present invention has strong universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a schematic diagram of an active distribution network with T-connection;

[0047] Figure 2 This is the main topological structure diagram of the inverter power supply;

[0048] Figure 3 A flow chart of a fault section location method based on transient high-frequency energy provided by the present invention;

[0049] Figure 4 for Figure 1 The high-frequency additional network diagram of the fault when the fault occurs in the MN area of ​​the line;

[0050] Figure 5 A flow chart of a fault section location method based on transient high-frequency energy, taking the 10kV active distribution network provided by the present invention as an example;

[0051] Figure 6 This is the topology diagram of the 10kV active distribution network simulation model;

[0052] Figure 7 It is a simulation diagram of high-frequency electrical quantities on the M side and the N side provided by the present invention; Figure 7 (a) is the high-frequency power diagram on both sides. Figure 7 (b) is the high-frequency energy diagram on both sides. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The purpose of the present invention is to provide a method, system and product for locating a fault section based on transient high-frequency energy, which can locate the fault section by using double-end information for a distribution network to which PV is connected in a T-connection manner.

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Embodiment 1

[0057] Figure 1 The figure is a schematic diagram of an active distribution network with T-connection. The left side S represents the system power supply located upstream of the fault point f, the right side X represents the system power supply located downstream of the fault point f, and PV is the photovoltaic power supply. Assuming that a three-phase short circuit fault occurs inside the line MN, α is the fault location parameter, which represents the ratio of the distance from the fault point f to the busbar M to the total length of the line MN.

[0058] The DC power generated by the photovoltaic array is converted into AC power by the inverter and then connected to the power grid through the L-type filter circuit. Figure 1 shown. Figure 2 This is the main topology diagram of the inverter power supply. Figure 2 Middle C d is the DC side stabilizing capacitor, R and L are the internal parameters of the filter, and the three-phase parameters are the same.

[0059] Jia K, Ren Z, Li L, et al. High-frequency transient comparison based fault location in distribution systems with DGs [J]. IET Generation, Transmission & Distribution, 2017, 11 (16): 4068-4077. Based on the flow path of high-frequency current during phase short circuit, four possible high-frequency impedance structures of photovoltaic power sources are summarized, and can be uniformly expressed as the form of RLC series circuit. In order to make the phase angle characteristics of the high-frequency impedance of the photovoltaic power source close to the line, that is, the photovoltaic power source can be equivalent to a resistance-inductive element, the lower limit of the selected frequency band should be selected according to the high-frequency equivalent impedance angle of PV being greater than or equal to the line impedance angle. In the present invention, the line impedance angle is selected as 53°.

[0060] The principles for selecting frequency bands are as follows:

[0061] Based on the above analysis, the lower limit of the selected frequency band can be determined, and the upper limit of the selected frequency band can be selected according to the following principles:

[0062] The upper limit of the selected frequency band needs to consider three constraints. First, according to the sampling theorem, the sampling frequency should be greater than twice the highest frequency in the selected frequency band; second, the sampling frequency should be combined with the actual engineering application background and should not exceed the computing power of the existing data processing hardware, usually not exceeding 10kHz. Third, the selected frequency cannot exceed the critical value of the additional impact of the line distributed capacitance. The frequency of the transient current of the line distributed capacitance is consistent with the natural frequency of the traveling wave, and the theoretical minimum value of the natural frequency of the traveling wave is:

[0063] f min =ν / 4d (1)

[0064] Where: v is the speed of the traveling wave, d is the fault distance.

[0065] Considering that the transmission distance of a 10kV AC distribution network is generally within 6-20km, it can be assumed that the fault distance d will not exceed 20km. For the high-frequency component of the traveling wave, its wave speed is about 97% to 99% of the speed of light. Based on this, it can be calculated that the main frequency of the natural frequency of the traveling wave will not be lower than 3600Hz. The frequency band selected by the present invention is 2800-3000Hz.

[0066] Figure 3 The flowchart of the fault section location method based on transient high-frequency energy provided by the present invention is as follows: Figure 3 As shown, a method for locating a fault section based on transient high-frequency energy includes:

[0067] Step 301: Establish a simulation model of an active distribution network in a T-connection form.

[0068] In practical applications, when the selected frequency band meets the above frequency selection principles, the influence of the line-to-ground distributed capacitance on transient high-frequency electrical quantities can be ignored. Based on the above analysis, the equivalent network of the system's fault transient high-frequency component can be obtained. Figure 4 for Figure 1 The high-frequency additional network diagram of the fault when the line fails in the MN area is as follows: Figure 4 shown.

[0069] M and O are both busbars, N is the grid connection point when PV is connected to the grid in T-connection form, Z MS , Z OX are the equivalent high-frequency impedances of the upstream and downstream system power supplies at the fault point; Z PV is the equivalent high-frequency impedance of the photovoltaic power source; Z MN is the equivalent high-frequency impedance of line MN; ΔU f is the fault high frequency voltage source; ΔU M and ΔU N are the high frequency voltages at M and N respectively; ΔI M and ΔI N are the high frequency currents flowing through M and N respectively.

[0070] Step 302: Based on the active distribution network simulation model, monitor the M-side fault signal in the system upstream of the fault point and the N-side fault signal in the system downstream of the fault point; the M-side fault signal includes the M-side fault voltage component and the M-side fault current component; the N-side fault signal includes the N-side fault voltage component and the N-side fault current component; M is the bus node; N is the grid connection point when the PV is connected to the grid in a T-connected form.

[0071] Step 303: extract the M-side fault high-frequency component information according to the M-side fault signal, and extract the N-side fault high-frequency component information according to the N-side fault component signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault component signal includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component.

[0072] The step 303 specifically includes: extracting the high-frequency component information of the M-side fault by using the wavelet packet transform method according to the M-side fault signal; and extracting the high-frequency component information of the N-side fault by using the wavelet packet transform method according to the N-side fault component signal.

[0073] In practical applications, Z NSis the equivalent high-frequency impedance between node N and the back power supply S. Since the two-terminal electrical quantity is the equivalent impedance of the back side, the load and generator impedance will change with the frequency. Therefore, the equivalent high-frequency impedance is the equivalent impedance value of the back side of the detection points M and O at different frequencies. Then Z NS It is expressed as:

[0074] Z NX =Z NO +Z OX (2)

[0075]

[0076]

[0077] Among them, Z NX is the equivalent impedance value of the back side of N; Z NO is the equivalent impedance value between the PV grid-connected point and the busbar O; Z OX is the equivalent impedance value of the back side of busbar O; R NX is the equivalent resistance value of the N back side; L NX is the equivalent reactance value of N back side; θ NX is the impedance angle of the equivalent impedance on the back side of N; ω is the angular frequency; j is a complex operator.

[0078] Similarly, the equivalent high-frequency impedance on the back side of N can be uniformly expressed as Z eq :

[0079]

[0080] Where: θ eq ∈{min(θ NX ,θ PV ),max(θ NX ,θ PV )}; L eq L is the equivalent reactance value of N back side NX High frequency reactance L equivalent to photovoltaic power supply PV The parallel result of PV is the impedance angle of PV equivalent impedance; Z NX (ω) is the equivalent impedance value of the back side of N at a specific angular frequency ω; Z PV (ω) is the PV equivalent impedance value at a specific angular frequency ω.

[0081] In high frequency networks, Z NX and Z PV Both are highly inductive, so their impedance angles are both at (0°, 90°), so the equivalent impedance Z formed after parallel connection is eq Still inductive. Therefore, the equivalent impedance Z eq It can be treated as a resistive-inductive component.

[0082] In order to qualitatively analyze the distribution of transient energy frequency characteristics in the upstream and downstream areas of the fault point, the present invention simplifies the transient high-frequency voltage source at the fault point into a unit step signal, and its frequency domain form is recorded as 1 / (jω). M (ω), ΔU N (ω) are the frequency domain forms corresponding to the instantaneous values ​​of the fault voltage components at the upstream and downstream protection installations of the fault point.

[0083] Depend on Figure 4 The circuit structure shown can be obtained:

[0084]

[0085]

[0086] Among them, Z MS is the equivalent impedance on the back side of busbar M; is the voltage value corresponding to the bus M at a specific angular frequency ω; is the voltage value corresponding to the bus N at a specific angular frequency ω; α is the fault location parameter.

[0087] According to the circuit relationship, the frequency domain expressions of the voltage and current fault components at both ends are respectively subjected to inverse Fourier transform to obtain the time domain expressions of the voltage and current components at the M and N nodes at high frequency:

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] Among them, e is 2.7; τ1 is the current decay constant on the back side of M; R MS is the equivalent resistance value of the back side of M; R MN is the resistance value of line MN; L MS is the equivalent reactance value of the back side of M; L MN is the reactance value of line MN; τ2 is the current attenuation constant on the back side of N; R NX is the equivalent resistance value of the N back side; R eq is the equivalent resistance value of N back side R NX High frequency resistance R equivalent to photovoltaic power supply PV The parallel result ofeq L is the equivalent reactance value of N back side NX High frequency reactance L equivalent to photovoltaic power supply PV The parallel result.

[0095] Considering that the selected data window length is extremely short, it can be considered that the attenuation term in formula (8) is only slightly less than 1 during the entire analysis process. Therefore, the negative term in formula (8) plays a dominant role. Therefore, when analyzing transient high-frequency processes, formula (8) is less than 0.

[0096] For (9), transform it into the following form:

[0097]

[0098]

[0099] Obviously, both A and C are less than 0, while the value of B is the same as the numerator (L MS R L -R MS L MN ) related.

[0100] Since B contains a decay term, |B| reaches its maximum value when t=0. Assuming (L MS R L -R MS L MN ) is greater than 0, then formula (9) is obviously greater than 0, and when (L MS R L -R MS L MN ) is less than 0, it is difficult to intuitively determine the positive or negative situation of formula (9). However, it can be deduced and proved that the positive or negative situation of item B is consistent with (L MS R L -R MS L MN ), and formula (9) is always greater than 0. The proof process is as follows:

[0101] Let t = 0, and assume that (L MS R L -R MS L MN ) is less than 0, then the problem of judging the positive and negative situation of formula (9) is transformed into judging the size relationship between formula (16) and formula (17).

[0102]

[0103]

[0104] Assuming |C|>|B|, combining (16) and (17) we can obtain:

[0105] (αL MS R MN -αR MS L MN )<(L MS +αL MN )R MS (18)

[0106] Since the equivalent resistance of the generator calculated to the high voltage side is greater than the line resistance, that is, R MS >αR MN Therefore, the relationship in formula (18) holds.

[0107] Therefore, within the total time window of transient high-frequency analysis, formula (8) is always less than 0, and formula (9) is always greater than 0, that is:

[0108]

[0109] Similarly, due to R eq >(1-α)R MN , so (10) and (11) satisfy the following relationship:

[0110]

[0111] The above analysis is only performed when the fault voltage component undergoes a step; conversely, when the fault voltage component drops, by the same token, the high-frequency voltage measured at each node upstream of the fault point is less than 0 and the high-frequency current is greater than 0, but the product of the voltage and current in the high-frequency network is still less than 0, which is consistent with the result when the fault voltage component undergoes a step. Therefore, the representation of this method in the fault phase is consistent.

[0112] Step 304: Determine the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information.

[0113] In practical applications, consider the transient energy e, where e is equal to the integral of the product of voltage and current. From the above analysis, it can be seen that the transient high-frequency energy distribution rules on both sides of the fault point are completely opposite. Transient energy is actually the energy carried by the transient wave formed by the transient traveling wave reflected back and forth on the transmission line. The fault point is equivalent to an energy source, from which energy is emitted and passes through the lines located upstream and downstream of the fault point, and is finally consumed in the resistive element. Therefore, the correctness of the above conclusion is also verified by the perspective of traveling waves.

[0114] Based on this, the definition of action high-frequency energy and braking high-frequency energy is as follows:

[0115]

[0116] Step 305: Locate the fault location according to the action high-frequency energy and the braking high-frequency energy; the fault location is an in-zone fault on the line or an out-of-zone fault outside the line.

[0117] In summary, there is a significant difference in the relationship between the action high-frequency energy and the braking high-frequency energy during in-zone and out-zone faults, as shown in formula (22).

[0118]

[0119] Since the sampled data are all in discrete form, in order to facilitate calculation, the transient energy e is redefined and expressed as shown in formula (23).

[0120]

[0121] In the formula, n is the total number of data points in the selected time window of all fault phases, f is the frequency band corresponding to the sampling point, and the product of voltage and current corresponding to a single sampling point is called transient power. Therefore, the protection identification criterion is constructed by combining the fault characteristics of formula (23) and formula (22) as shown in formula (24), where k = e act / e res , denoted as the high-frequency energy ratio, where k will not be equal to 1.

[0122]

[0123] Taking 10kV active distribution network as an example, Figure 5 The flow chart of the fault section location method based on transient high-frequency energy is shown in the figure, taking the 10kV active distribution network provided by the present invention as an example. Figure 5 shown.

[0124] Use Matlab / Simulink to establish a 10kV active distribution network simulation model. Figure 6 This is the topology diagram of the 10kV active distribution network simulation model, such as Figure 6 As shown. There are 3 overhead lines in the system, which are L1 branch (line LM, 3km), L2 branch (line MO, 5km), L3 branch (line OR, 3km), k1 is the preset fault point, and the distance between the fault point k1 and the M end is 1km. Table 1 is the line and photovoltaic power supply parameter configuration table. The relevant parameters of PV and lines are detailed in Table 1.

[0125]

[0126]

[0127] In the simulation analysis, α=1 / 3, the sampling frequency is 10kHz, and the recorded data in the 2.5ms time window before and after the protection device is activated are extracted. When a metallic three-phase short circuit fault occurs in the L2 area (k1) of the branch, the present invention performs simulation analysis from three aspects: section positioning, relative position determination between the fault point and PV, and fault distance measurement. The specific positioning steps are as follows.

[0128] The fault component voltage and fault current signals within the 5ms data window are collected, and the high-frequency information of their respective fault components is extracted using wavelet packet transform. The wavelet basis function is db3, and the number of decomposition layers is 4. The results of multiplying the fault high-frequency voltage signal and the fault high-frequency current signal of each phase in the fault phase on both sides of M and O are summed to obtain the high-frequency energy on the M and O sides, and then the corresponding action and braking high-frequency energy are obtained according to formula (21). Figure 7 This is a simulation diagram of high-frequency electrical quantities on the M side and the N side provided by the present invention, wherein: Figure 7 (a) is the high-frequency power diagram on both sides. Figure 7 (b) is the high-frequency energy diagram on both sides. The specific results are as follows Figure 7 shown.

[0129] Depend on Figure 7 (b) It can be seen that the action high-frequency energy is greater than the braking high-frequency energy. According to formula (22), it is determined that there is a fault inside the MN line. Table 2 shows the identification results under different short-circuit fault scenarios. Table 2 shows the simulation results under other metallic short-circuit fault scenarios.

[0130] Table 2

[0131]

[0132] It can be seen from Table 2 that under different fault types, only the action high-frequency energy corresponding to the fault section is greater than the braking high-frequency energy. Faced with different types of interphase faults, the protection fault section location strategy can correctly distinguish between internal and external faults, indicating that this protection method has strong universality.

[0133] Embodiment 2

[0134] In order to execute the method corresponding to the above-mentioned embodiment 1 to achieve the corresponding functions and technical effects, a fault section locating system based on transient high-frequency energy is provided below.

[0135] A fault section location system based on transient high-frequency energy, comprising:

[0136] The active distribution network simulation model establishment module is used to establish the active distribution network simulation model under the T-connection form.

[0137] The M-side fault signal and N-side fault signal monitoring module is used to monitor the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point based on the active distribution network simulation model; the M-side fault signal includes the M-side fault voltage component and the M-side fault current component; the N-side fault signal includes the N-side fault voltage component and the N-side fault current component; M is the bus node; N is the grid connection point when the PV is connected to the grid in a T-connected form.

[0138] The M-side fault high-frequency component information and N-side fault high-frequency component information extraction module is used to extract the M-side fault high-frequency component information according to the M-side fault signal, and to extract the N-side fault high-frequency component information according to the N-side fault component signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault component signal includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component.

[0139] In practical applications, the M-side fault high-frequency component information and N-side fault high-frequency component information extraction module specifically include: an M-side fault high-frequency component information extraction unit, which is used to extract the M-side fault high-frequency component information by using a wavelet packet transform method according to the M-side fault signal; and an N-side fault high-frequency component information extraction unit, which is used to extract the N-side fault high-frequency component information by using a wavelet packet transform method according to the N-side fault component signal.

[0140] The action high-frequency energy and braking high-frequency energy determination module is used to determine the action high-frequency energy and braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information.

[0141] The fault location positioning module is used to locate the fault location according to the action high-frequency energy and the braking high-frequency energy; the fault location is an in-zone fault on the line or an out-of-zone fault outside the line.

[0142] Embodiment 3

[0143] An embodiment of the present invention provides an electronic device including a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the fault section locating method based on transient high-frequency energy of embodiment 1.

[0144] In practical applications, the above electronic device may be a server.

[0145] In practical applications, an electronic device includes: at least one processor, a memory, a bus and a communications interface.

[0146] Wherein: the processor, the communication interface, and the memory communicate with each other via a communication bus.

[0147] Communication interface, used to communicate with other devices.

[0148] The processor is used to execute the program, and specifically can execute the method described in the above embodiment.

[0149] Specifically, the program may include program codes including computer operation instructions.

[0150] The processor may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention. The one or more processors included in the electronic device may be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.

[0151] The memory is used to store programs. The memory may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory.

[0152] Based on the description of the above embodiments, the embodiments of the present application provide a storage medium on which computer program instructions are stored. The computer program instructions can be executed by a processor to implement the method described in any embodiment.

[0153] The fault section location system based on transient high-frequency energy provided in the embodiments of the present application exists in various forms, including but not limited to:

[0154] (1) Mobile communication devices: These devices are characterized by their mobile communication functions and their main purpose is to provide voice and data communications. These terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones.

[0155] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing functions, and generally also have mobile Internet access capabilities. These terminals include: PDA, MID and UMPC devices, such as iPad.

[0156] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players (such as iPods), handheld game consoles, e-books, smart toys, and portable car navigation devices.

[0157] (4) Other electronic devices with data interaction functions.

[0158] Thus far, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired results. Additionally, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing may be advantageous.

[0159] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0160] For the convenience of description, the above device is described by being divided into various units according to their functions and described separately. Of course, when implementing the present application, the functions of each unit can be implemented in one or more software and / or hardware. It should be understood by those skilled in the art that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0161] 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.

[0162] 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.

[0163] 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 The steps for the functions specified in one or more boxes.

[0164] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0165] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0166] Computer-readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM),

[0167] Digital Versatile Disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device

[0168] Or any other non-transmission medium that can be used to store information that can be accessed by a computing device. According to the definition in this article, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0169] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0170] 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 on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0171] The present application may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific transactions or implement specific abstract data types. The present application may also be practiced in distributed computing environments where transactions are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0172] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0173] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for locating a fault section based on transient high-frequency energy, characterized in that: include: Establish a simulation model of active distribution network in T-connection form; Based on the active distribution network simulation model, monitor the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point; the M-side fault signal includes the M-side fault voltage component and the M-side fault current component; The N-side fault signal includes an N-side fault voltage component and an N-side fault current component; M is the bus node; N is the grid connection point when PV is connected to the grid in T-connection form; Extracting the M-side fault high-frequency component information according to the M-side fault signal, and extracting the N-side fault high-frequency component information according to the N-side fault signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault high-frequency component information includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component; The time domain expression of the high-frequency current component of the M-side fault is for: ; where e is 2.7; is the current decay constant on the back side of M, ; is the equivalent resistance value of the back side of M; is the resistance value of line MN; is the fault location parameter; The time domain expression of the high-frequency voltage component of the M-side fault is for: ;in, is the equivalent reactance value of the back side of M; is the reactance value of line MN; The time domain expression of the high-frequency current component of the N-side fault is for: ;in, is the current decay constant on the N back side, ; is the equivalent resistance value of the N back side; The time domain expression of the high-frequency voltage component of the N-side fault is for: ;in, N back side equivalent resistance R NX High frequency resistance equivalent to photovoltaic power supply R PV The parallel result of N is the back side equivalent reactance value L NX High frequency reactance equivalent to photovoltaic power source L PV The parallel result of Determine the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information; The fault position is located according to the action high-frequency energy and the braking high-frequency energy; the fault position is an in-zone fault on the line or an out-of-zone fault outside the line.

2. The method for locating a fault section based on transient high-frequency energy according to claim 1, characterized in that: The extracting the high-frequency component information of the M-side fault according to the M-side fault signal, and extracting the high-frequency component information of the N-side fault according to the N-side fault signal, specifically includes: According to the M-side fault signal, a wavelet packet transform method is used to extract the high-frequency component information of the M-side fault; According to the N-side fault signal, the high-frequency component information of the N-side fault is extracted using a wavelet packet transform method.

3. The method for locating a fault section based on transient high-frequency energy according to claim 2, characterized in that: The determining of the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information specifically includes: The product of the M-side fault high-frequency voltage component and the M-side fault high-frequency current component is determined as the M-side transient high-frequency energy; The product of the N-side fault high-frequency voltage component and the N-side fault high-frequency current component is determined as the N-side transient high-frequency energy; Determine the absolute value of the difference between the M-side transient high-frequency energy and the N-side transient high-frequency energy as the action high-frequency energy; The absolute value of the sum of the M-side transient high-frequency energy and the N-side transient high-frequency energy is determined as the braking high-frequency energy.

4. The method for locating a fault section based on transient high-frequency energy according to claim 3 is characterized in that: The locating the fault position according to the action high-frequency energy and the braking high-frequency energy specifically includes: determining a ratio of the action high-frequency energy to the braking high-frequency energy as a high-frequency energy ratio; When the high frequency energy ratio is greater than 1, determining that the fault location is an intra-area fault on the line; When the high frequency energy ratio is less than 1, it is determined that the fault location is an out-of-zone fault outside the line.

5. A fault section location system based on transient high-frequency energy, characterized in that: include: Active distribution network simulation model building module, used to build the active distribution network simulation model under T-connection form; An M-side fault signal and an N-side fault signal monitoring module, for monitoring the M-side fault signal in the upstream system of the fault point and the N-side fault signal in the downstream system of the fault point based on the active distribution network simulation model; the M-side fault signal includes an M-side fault voltage component and an M-side fault current component; The N-side fault signal includes an N-side fault voltage component and an N-side fault current component; M is the bus node; N is the grid connection point when PV is connected to the grid in T-connection form; An M-side fault high-frequency component information and an N-side fault high-frequency component information extraction module, used to extract the M-side fault high-frequency component information according to the M-side fault signal, and to extract the N-side fault high-frequency component information according to the N-side fault signal; the M-side fault high-frequency component information includes the M-side fault high-frequency voltage component and the M-side fault high-frequency current component; the N-side fault high-frequency component information includes the N-side fault high-frequency voltage component and the N-side fault high-frequency current component; An action high-frequency energy and a braking high-frequency energy determination module, used to determine the action high-frequency energy and the braking high-frequency energy according to the M-side fault high-frequency component information and the N-side fault high-frequency component information; The time domain expression of the high-frequency current component of the M-side fault is for: ; where e is 2.7; is the current decay constant on the back side of M, ; is the equivalent resistance value of the back side of M; is the resistance value of line MN; is the fault location parameter; The time domain expression of the high-frequency voltage component of the M-side fault is for: ;in, is the equivalent reactance value of the back side of M; is the reactance value of line MN; The time domain expression of the high-frequency current component of the N-side fault is for: ;in, is the current decay constant on the N back side, ; is the equivalent resistance value of the N back side; The time domain expression of the high-frequency voltage component of the N-side fault is for: ;in, N back side equivalent resistance R NX High frequency resistance equivalent to photovoltaic power supply R PV The parallel result of N is the back side equivalent reactance value L NX High frequency reactance equivalent to photovoltaic power source L PV The parallel result of The fault location positioning module is used to locate the fault location according to the action high-frequency energy and the braking high-frequency energy; the fault location is an in-zone fault on the line or an out-of-zone fault outside the line.

6. The fault section locating system based on transient high-frequency energy according to claim 5 is characterized in that: The M-side fault high-frequency component information and N-side fault high-frequency component information extraction module specifically includes: An M-side fault high-frequency component information extraction unit is used to extract the M-side fault high-frequency component information by using a wavelet packet transform method according to the M-side fault signal; The N-side fault high-frequency component information extraction unit is used to extract the N-side fault high-frequency component information by using a wavelet packet transform method according to the N-side fault signal.

7. An electronic device, characterized in that: It comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the fault section locating method based on transient high-frequency energy as described in any one of claims 1 to 4.

8. A computer-readable storage medium, characterized in that: It stores a computer program, and when the computer program is executed by a processor, the fault section locating method based on transient high-frequency energy as described in any one of claims 1 to 4 is implemented.

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