Inverter power supply outgoing line fault protection method, device, equipment and storage medium

Abstract

The invention discloses an inverter power supply outgoing line fault protection method, device and equipment and a storage medium, and relates to the technical field of power grid fault protection. The specific scheme comprises the following steps: respectively acquiring voltage samples and current samples of two relay protection devices; determining that a fault occurs; for each relay protection device, calculating a voltage fault component and a current fault component according to the voltage sample and the current sample; determining a voltage fault modulus and a current fault modulus according to the voltage fault component and the current fault component; determining a fault relative direction corresponding to the relay protection device according to the voltage fault modulus and the current fault modulus; and determining that the fault is located between the two relay protection devices according to the fault relative directions of the two relay protection devices, and sending a protection instruction for indicating protection tripping to the two relay protection devices. According to the invention, various problems on the inverter type power supply outgoing line in the prior art can be solved, and the reliability of fault protection of the inverter type power supply outgoing line is improved.

Description

Technical Field

[0001] The present application relates to the technical field of power grid fault protection, and in particular to a method, device, equipment and storage medium for protecting an inverter power supply output line from fault. Background Art

[0002] Photovoltaic and wind power are mainly connected to the power system in a large-scale access and centralized transmission mode, which transforms the power source from the traditional synchronous power source to the inverter power source. The fault characteristics of the inverter power source mainly include weak feed, changes in power source impedance, and different positive and negative sequence impedances, which are quite different from the fault characteristics of the traditional synchronous power source, resulting in the traditional fault protection method being inapplicable to the inverter power transmission line.

[0003] Traditional fault protection methods generally include distance protection methods, longitudinal protection methods, and traveling wave protection methods. On inverter-type power transmission lines, the distance protection method may cause the protection device (i.e., relay protection device) to incorrectly operate (e.g., the protection device trips when it should not trip) or there is an operation dead zone (i.e., the protection device will not trip) in the case of a near-field fault; the longitudinal protection method may have problems such as limited applicability of fault types (only applicable to ground faults), or a high required sampling rate, or a transition resistance fault that reduces the protection sensitivity; the traveling wave protection method may have problems such as difficulty in implementation when the power supply voltage fails near the zero crossing point or when the initial traveling wave is not detected, or a high required sampling rate.

[0004] In summary, it is urgent to study a fault protection method suitable for inverter power supply transmission line. Summary of the invention

[0005] The embodiments of the present application solve various problems that occur in the prior art on the inverter power supply transmission line by providing an inverter power supply transmission line fault protection method, device, equipment and storage medium, and improve the reliability of the inverter power supply transmission line fault protection.

[0006] In a first aspect, an embodiment of the present application provides a method for protecting an inverter power outgoing line from a fault, comprising:

[0007] Respectively obtain voltage samples and current samples of two relay protection devices; determine the occurrence of a fault; for each relay protection device, calculate the voltage fault component and the current fault component based on the voltage sample and the current sample; determine the voltage fault modulus and the current fault modulus based on the voltage fault component and the current fault component; determine the relative direction of the fault corresponding to the relay protection device based on the voltage fault modulus and the current fault modulus; determine that the fault is located between the two relay protection devices based on the relative directions of the faults of the two relay protection devices, and send a protection instruction to the two relay protection devices, the protection instruction being used to instruct the relay protection device to perform a protection trip.

[0008] Further, determining that a fault occurs includes: determining that a fault occurs when the current sample satisfies the fault discrimination formula based on the current sample and the fault discrimination formula.

[0009] The fault judgment formula is shown in formula (1):

[0010]

[0011] In formula (1), k represents the index number of the current sample, ε is the preset discrimination threshold, Δi(m) represents the current fault component corresponding to the mth current sample, and Δi(n) represents the current fault component corresponding to the nth current sample.

[0012] Further, the voltage fault component and the current fault component are calculated according to the voltage sample and the current sample, including: taking the time corresponding to the occurrence of the fault as the starting time, and determining the voltage fault component and the current fault component according to the fault component calculation formula, the voltage sample and the current sample.

[0013] The fault component calculation formula is shown in formula (2):

[0014]

[0015] In formula (2), Δu(t) represents the voltage fault component at time t, u(t) represents the voltage at time t, u(tT) represents the voltage at time tT, T represents the fundamental wave period, Δi(t) represents the current fault component at time t, i(t) represents the current at time t, and i(tT) represents the current at time tT.

[0016] Furthermore, the voltage fault modulus and the current fault modulus are determined according to the voltage fault component and the current fault component, including: determining the voltage fault modulus according to the voltage fault component and the voltage fault modulus determination formula; determining the current fault modulus according to the current fault component and the current fault modulus determination formula.

[0017] The voltage fault modulus determination formula is shown in formula (3):

[0018]

[0019] In formula (3), Δu α represents the α modulus of the voltage fault component after phase modulus transformation, i.e., the voltage fault modulus; Δu a Indicates the a-phase component of the voltage fault component; Δu b Represents the b-phase component of the voltage fault component.

[0020] The formula for determining the current fault modulus is shown in formula (4):

[0021]

[0022] In formula (4), Δi α represents the α modulus of the voltage fault component after phase modulus transformation, that is, the current fault modulus; Δi a Indicates the a-phase component of the current fault component; Δi b Represents the b-phase component of the current fault component.

[0023] Furthermore, the relative direction of the fault corresponding to the relay protection device is determined based on the voltage fault modulus and the current fault modulus, including: determining the adaptive transient energy based on the voltage fault modulus and the current fault modulus and the adaptive transient energy calculation formula; determining the relative direction of the fault corresponding to the relay protection device based on the positive and negative value of the adaptive transient energy.

[0024] The adaptive transient energy calculation formula is shown in formula (5):

[0025] C=||Δu α ||·||Δi α ||E(5)

[0026] In formula (5), C represents the adaptive transient energy; Δu α The α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the voltage fault modulus; Δi α represents the α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the current fault modulus; E represents the transient energy, Where i represents the index number of the voltage fault component and the current fault component, and N represents the total number of sampling points within the data window duration.

[0027] Furthermore, the preset discrimination threshold ε is determined according to the sensitivity requirement of the application scenario.

[0028] Further, according to the relative directions of the faults of the two relay protection devices, determining that the fault is located between the two relay protection devices includes: when the relative directions of the faults of the two relay protection devices are both positive directions, determining that the fault is located between the two relay protection devices.

[0029] In a second aspect, an embodiment of the present application provides an inverter-type power supply transmission line fault protection device, including: an acquisition module, a fault judgment module, a direction determination module and an indication module.

[0030] The acquisition module is used to respectively acquire voltage samples and current samples of two relay protection devices.

[0031] The fault identification module is used to determine whether a fault occurs.

[0032] The direction determination module is used to calculate the voltage fault component and the current fault component for each relay protection device based on the voltage sample and the current sample; determine the voltage fault modulus and the current fault modulus based on the voltage fault component and the current fault component; and determine the relative fault direction corresponding to the relay protection device based on the voltage fault modulus and the current fault modulus.

[0033] The indication module is used to determine that the fault is located between the two relay protection devices according to the relative directions of the faults of the two relay protection devices, and send protection instructions to the two relay protection devices, wherein the protection instructions are used to instruct the relay protection devices to perform protection tripping.

[0034] In a third aspect, an embodiment of the present application provides a device, comprising: a processor; a memory for storing processor executable instructions; and a method for implementing the first aspect or any possible implementation of the first aspect when the processor executes the executable instructions.

[0035] In a fourth aspect, an embodiment of the present application provides a non-volatile computer-readable storage medium, which includes a device for storing a computer program or instruction. When the computer program or instruction is executed, the method of the first aspect or any possible implementation method of the first aspect is implemented.

[0036] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0037] The embodiment of the present application obtains voltage samples and current samples of two relay protection devices respectively; determines the occurrence of a fault; for each relay protection device, calculates the voltage fault component and the current fault component according to the voltage sample and the current sample; determines the voltage fault modulus and the current fault modulus according to the voltage fault component and the current fault component; determines the relative direction of the fault corresponding to the relay protection device according to the voltage fault modulus and the current fault modulus; determines that the fault is located between the two relay protection devices according to the relative direction of the faults of the two relay protection devices, and sends protection instructions to the two relay protection devices. It is not affected by factors such as the weak feedback characteristics of the inverter-type new energy, changes in power supply impedance, and inconsistency of positive and negative sequence impedances, and is not affected by the fault starting angle, fault location, and transition resistance. The required sampling rate can match the sampling rate that can be provided by current commercial relays, and a higher sampling rate is not required, thereby improving the reliability of fault protection for the inverter-type power supply transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 A schematic diagram of a flow chart of a method for protecting an inverter power outgoing line from a fault provided in an embodiment of the present application;

[0040] Figure 2 A schematic diagram of an inverter power supply transmission line system provided in this embodiment;

[0041] Figure 3 Relay protection device R S Schematic diagram of the equivalent circuit of the positive direction fault;

[0042] Figure 4 Relay protection device R S Schematic diagram of the reverse fault equivalent circuit;

[0043] Figure 5 This is a schematic diagram of another inverter type power supply outgoing line system;

[0044] Figure 6 To obtain the relay protection device R S Schematic diagram of voltage samples;

[0045] Figure 7 To obtain the relay protection device R S Schematic diagram of the current sample;

[0046] Figure 8 To obtain the relay protection device R P Schematic diagram of voltage samples;

[0047] Fig. 9 To obtain the relay protection device R P Schematic diagram of the current sample;

[0048] Fig.10 To obtain the relay protection device R S Schematic diagram of voltage fault components;

[0049] Fig.11 To obtain the relay protection device R S Schematic diagram of the current fault component;

[0050] Fig.12 To obtain the relay protection device R P Schematic diagram of voltage fault components;

[0051] Fig.13 To obtain the relay protection device R P Schematic diagram of the current fault component;

[0052] Fig.14 A schematic diagram of the composition of an inverter-type power supply output line fault protection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are 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 following describes some of the techniques involved in the embodiments of the present application to facilitate understanding, and they should be considered as merely exemplary. Therefore, it should be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, some descriptions of well-known functions and structures are omitted in the following description.

[0055] Photovoltaic and wind power are mainly connected to the power system in a large-scale access and centralized transmission mode, which transforms the power source from the traditional synchronous power source to the inverter power source. The fault characteristics of the inverter power source mainly include weak feed, changes in power source impedance, and different positive and negative sequence impedances, which are quite different from the fault characteristics of the traditional synchronous power source, resulting in the traditional fault protection method being inapplicable to the inverter power transmission line.

[0056] Traditional fault protection methods generally include distance protection methods, longitudinal protection methods, and traveling wave protection methods. On inverter-type power transmission lines, the distance protection method may cause the protection device (i.e., relay protection device) to incorrectly operate (e.g., the protection device trips when it should not trip) or there is an operation dead zone (i.e., the protection device will not trip) in the case of a near-field fault; the longitudinal protection method may have problems such as limited applicability of fault types (only applicable to ground faults), or a high required sampling rate, or a transition resistance fault that reduces the protection sensitivity; the traveling wave protection method may have problems such as difficulty in implementation when the power supply voltage fails near the zero crossing point or when the initial traveling wave is not detected, or a high required sampling rate.

[0057] Specifically, distance protection: 1) Positive-sequence voltage polarization distance protection, due to the time-varying characteristics of the impedance of the inverter-type renewable energy power source, leads to incorrect protection operation; affected by transient ride-through control and negative-sequence current suppression strategies, it is easy for phase-to-phase faults within the zone to refuse to operate, and for phase-to-phase faults outside the zone to misoperate; 2) Time domain distance protection, although not affected by changes in the power source impedance characteristics, but there is an operation dead zone in the event of a near-zone fault, and the weak feedback of renewable energy will make this phenomenon more serious.

[0058] Specifically, longitudinal protection: 1) Based on the zero-sequence measurement impedance of forward and reverse grounding faults, a method for setting the maximum sensitivity angle and action zone of the zero-sequence directional element is proposed, but this method is only applicable when a grounding fault occurs and is limited by the type of fault; 2) Distance protection of high-frequency mutation quantity, by selecting the high-frequency impedance of the inverter-type new energy in the appropriate frequency band to be inductive, and then distinguishing the internal and external faults by comparing the high-frequency working voltage and the high-frequency voltage at the fault point. This method is not affected by the control strategy, and the nearby faults can be reliably judged, but the sampling rate is relatively high; 3) A fault direction discrimination element based on the Euclidean distance between the positive-sequence reactive current reference value and the calculated value is proposed. Although it is not affected by the inverter-type new energy fault crossing control strategy and its output, this method tolerates a small transition resistance. When a fault passes through the transition resistance, the protection sensitivity is reduced.

[0059] Specifically, the traveling wave protection: 1) determines the fault direction by comparing the polarity of the voltage traveling wave and the current traveling wave; 2) compares the amplitude and energy of the traveling waves in the positive and negative directions; 3) determines the fault direction by defining the composite surge impedance, which is defined as the ratio of the first voltage traveling wave to the first current traveling wave. The above traveling wave protection methods all rely on the wave head of the initial traveling wave. When the power supply voltage fails near the zero point or the initial traveling wave is not detected, the method is difficult to implement and requires a high sampling rate.

[0060] In summary, it is urgent to study a fault protection method suitable for inverter power transmission lines.

[0061] Against this background, the present invention provides a method for protecting an inverter power supply line from faults, which can overcome the problems existing in the prior art on the inverter power supply line and improve the reliability of the fault protection on the inverter power supply line.

[0062] The execution subject of the inverter power supply transmission line fault protection method provided by the embodiment of the present disclosure may be a computer or a server, or may also be other electronic devices with data processing capabilities; or, the execution subject of the method may also be a processor (such as a central processing unit (CPU)) in the above electronic device; or, the execution subject of the method may also be an application (application, APP) installed in the above electronic device that can implement the function of the method; or, the execution subject of the method may be a functional module or unit in the above electronic device that has the function of the method, etc. There is no limitation on the execution subject of the method herein.

[0063] The inverter power supply output line fault protection method is exemplarily described below with reference to the accompanying drawings.

[0064] Figure 1 It is a flow chart of the inverter power supply output line fault protection method provided in an embodiment of the present application.

[0065] in, Figure 1 This is only an execution order shown in the embodiment of the present application, and does not represent the only execution order of the inverter power supply output line fault protection method. In the case where the final result can be achieved, Figure 1 The steps shown can be performed in parallel or in reverse. Figure 1 As shown, the method may include:

[0066] S101. Obtain voltage samples and current samples of two relay protection devices respectively.

[0067] Exemplarily, two relay protection devices may be respectively arranged at two ends of the line between two busbars. Figure 2 This is a schematic diagram of the inverter power supply transmission line system provided in this embodiment. Figure 2 As shown, two relay protection devices can be respectively arranged at the two ends of the line between busbar S and busbar P, one of which (i.e., R S ) can be set at one end of the line close to the busbar S, and another relay protection device (i.e. R P ) can be set at one end of the line close to the busbar P.

[0068] Exemplarily, the executing entity may send collection instructions to two relay protection devices respectively. After receiving the collection instructions, the two relay protection devices collect the voltage and current of the line and send them to the executing entity, so that the executing entity obtains the voltage samples and current samples of the two relay protection devices; or the two relay protection devices may periodically send the collected voltage and current of the line to the executing entity, and there is no restriction on the acquisition of voltage and current.

[0069] It should be noted that the voltage sample obtained from the relay protection device includes three-phase voltage components a, b, and c, and the current sample also includes three-phase current components a, b, and c.

[0070] S102: Determine that a fault occurs.

[0071] Specifically, determining that a fault occurs includes: determining that a fault occurs according to a current sample and a fault discrimination formula when the current sample satisfies the fault discrimination formula.

[0072] The fault judgment formula is shown in formula (1):

[0073]

[0074] In formula (1), k represents the index number of the current sample, ε is the preset discrimination threshold, Δi(m) represents the current fault component corresponding to the mth current sample, and Δi(n) represents the current fault component corresponding to the nth current sample.

[0075] For example, the preset discrimination threshold ε has a value range of 0 to 1, and there is no restriction on the specific value, and it can generally be 0.4.

[0076] Exemplarily, the current fault component Δi(m) corresponding to the m-th current sample can be obtained by calculating the difference between the current i(q) at time q corresponding to the m-th current sample and the current i(qT) at time qT corresponding to the m-th current sample. Wherein, T represents the fundamental wave period. The method of obtaining the current fault component Δi(n) corresponding to the n-th current sample is similar to the method of obtaining the current fault component Δi(m) corresponding to the m-th current sample, and will not be repeated here.

[0077] Exemplarily, the three-phase current components of the current sample may be calculated separately, and when any phase current component of the three-phase current components satisfies formula (1), it is determined that a fault occurs.

[0078] Furthermore, the preset discrimination threshold ε can be determined according to the sensitivity requirement of the application scenario. When the sensitivity requirement of the application scenario is higher, the preset discrimination threshold ε is smaller; when the sensitivity requirement of the application scenario is lower, the preset discrimination threshold ε is larger.

[0079] It can be understood that the smaller the preset discrimination threshold ε is, the more sensitive the fault discrimination is, but the disadvantage is that some slight disturbances are easily misjudged as faults; the larger the preset discrimination threshold ε is, the higher the reliability of fault discrimination is, but the disadvantage is that some slight faults may not be detected.

[0080] It should be noted that the above example of determining the occurrence of a fault by using the fault identification formula (1) is only an exemplary description. In practical applications, the fault can also be determined by other related technologies, which is not limited here.

[0081] It should be noted that when it is determined that no fault has occurred, there is no need to perform subsequent steps.

[0082] S103. For each relay protection device, calculate the voltage fault component and the current fault component based on the voltage sample and the current sample; determine the voltage fault modulus and the current fault modulus based on the voltage fault component and the current fault component; determine the relative fault direction corresponding to the relay protection device based on the voltage fault modulus and the current fault modulus.

[0083] Specifically, the voltage fault component and the current fault component are calculated according to the voltage sample and the current sample, including: taking the time corresponding to the occurrence of the fault as the starting time, and determining the voltage fault component and the current fault component according to the fault component calculation formula, the voltage sample and the current sample.

[0084] The fault component calculation formula is shown in formula (2):

[0085]

[0086] In formula (2), Δu(t) represents the voltage fault component at time t, u(t) represents the voltage at time t, u(tT) represents the voltage at time tT, T represents the fundamental wave period, Δi(t) represents the current fault component at time t, i(t) represents the current at time t, and i(tT) represents the current at time tT.

[0087] In some possible implementations, the fundamental wave period T=0.02 seconds.

[0088] It should be noted that the three-phase voltage components of the voltage sample and the three-phase current components of the current sample can be calculated respectively by formula (2) to obtain the three-phase voltage fault component and the three-phase current fault component.

[0089] Specifically, the voltage fault modulus and the current fault modulus are determined according to the voltage fault component and the current fault component, including: determining the voltage fault modulus according to the voltage fault component and the voltage fault modulus determination formula; determining the current fault modulus according to the current fault component and the current fault modulus determination formula.

[0090] The voltage fault modulus determination formula is shown in formula (3):

[0091]

[0092] In formula (3), Δuα represents the α modulus of the voltage fault component after phase modulus transformation, i.e., the voltage fault modulus; Δu a Indicates the a-phase component of the voltage fault component; Δu b Represents the b-phase component of the voltage fault component.

[0093] The formula for determining the current fault modulus is shown in formula (4):

[0094]

[0095] In formula (4), Δi α represents the α modulus of the voltage fault component after phase modulus transformation, that is, the current fault modulus; Δi a Indicates the a-phase component of the current fault component; Δi b Represents the b-phase component of the current fault component.

[0096] For example, after obtaining the voltage fault component and the current fault component, the fault component phase mode can be transformed using the Karlenberg transformation. The Karlenberg transformations of the voltage fault component and the current fault component are shown in formula (6) and formula (7), respectively:

[0097]

[0098]

[0099] In formula (6) and formula (7), Δu0 represents the zero modulus of the voltage fault component after phase modulus transformation, Δu α represents the α modulus of the voltage fault component after phase transformation, Δu β represents the β modulus of the voltage fault component after phase mode transformation, Δu a Indicates the a-phase component of the voltage fault component, Δu b Indicates the b-phase component of the voltage fault component, Δu c represents the c-phase component of the voltage fault component, Δi0 represents the 0-modulus of the current fault component after phase modulus transformation, Δi α represents the α modulus of the current fault component after phase modulus transformation,

[0100] Δi β represents the β modulus of the current fault component after phase transformation, Δi a represents the a-phase component of the current fault component, Δi b represents the b-phase component of the current fault component, Δi c Represents the c-phase component of the current fault component.

[0101] It can be understood that formula (3) can be obtained by transforming formula (6), and formula (4) can be obtained by transforming formula (7).

[0102] Specifically, the relative direction of the fault corresponding to the relay protection device is determined according to the voltage fault modulus and the current fault modulus, including: determining the adaptive transient energy according to the voltage fault modulus and the current fault modulus and the adaptive transient energy calculation formula; determining the relative direction of the fault corresponding to the relay protection device according to the positive and negative value of the adaptive transient energy.

[0103] The adaptive transient energy calculation formula is shown in formula (5):

[0104] C=||Δu α ||·||Δi α ||E(5)

[0105] In formula (5), C represents the adaptive transient energy; Δu α The α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the voltage fault modulus; Δi α represents the α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the current fault modulus; E represents the transient energy, Where i represents the index number of the voltage fault component and the current fault component, and N represents the total number of sampling points within the data window duration.

[0106] For example, Figure 3 Relay protection device R S Schematic diagram of the equivalent circuit of the positive fault, Figure 4 Relay protection device R S Schematic diagram of the reverse direction fault equivalent circuit.

[0107] for Figure 3 and Figure 4 For the circuit, P(t)=Δu(t)Δi(t), Where P(t) represents the transient power after the fault, t1 represents the fault start time, τ represents the data window length, and E S It means that from the fault start time t1, within the data window length τ, the relay protection device R S The transient energy obtained.

[0108] For relay protection device R S , when a positive fault occurs, such as Figure 3 There is a fault at f1 shown. E1 and Respectively represent Z after fault N and the energy absorbed by line NS, where Z N is the equivalent impedance from the wind farm to the busbar N. When a reverse fault occurs, such as Figure 3 The fault occurs at f2 shown in the figure. E2 and Respectively represent Z after failure E and the energy absorbed by line SP, where Z E Is the equivalent impedance from the system side to the busbar P. E1, All are positive numbers.

[0109] It can be understood that since C and E have the same polarity, the polarity of C can indicate a fault. When C is greater than 0, the fault occurs in the reverse direction of the relay protection device (i.e., the reverse direction of the busbar to which the relay protection device is close), and when C is less than 0, the fault occurs in the positive direction of the relay protection device (i.e., the positive direction of the busbar to which the relay protection device is close).

[0110] Understandably, Figure 2 For example, for the relay protection device R S , when C is greater than 0, the fault occurs in the relay protection device R S The opposite direction, that is, R S On the left side, when C is less than 0, the fault occurs in the relay protection device R S The positive direction, that is, R S Right side; for relay protection device R P , when C is greater than 0, the fault occurs in the relay protection device R P The opposite direction, that is, R P On the right side, when C is less than 0, the fault occurs in the relay protection device R P The positive direction, that is, R P Left side.

[0111] It can be understood that after S103 is executed for both relay protection devices, S104 can be executed.

[0112] S104: Determine that the fault is located between the two relay protection devices according to the relative directions of the faults of the two relay protection devices, and send protection instructions to the two relay protection devices.

[0113] Among them, the protection instruction is used to instruct the relay protection device to perform protection tripping.

[0114] Specifically, when the relative directions of the faults of the two relay protection devices are both in the positive direction (ie, the C values ​​corresponding to the two relay protection devices are both less than 0), it is determined that the fault is located between the two relay protection devices.

[0115] For example, Figure 2 For example, when there is and It can be determined that the fault occurred in the relay protection device R S With relay protection device R P between.

[0116] It can be understood that after the two relay protection devices receive the protection instruction, they will perform protection tripping to protect the line between the two relay protection devices to prevent the fault from causing damage to the line.

[0117] It should be noted that, when it is determined that the fault is not located between two relay protection devices, no protection instruction is sent to the two relay protection devices.

[0118] The embodiment of the present application obtains voltage samples and current samples of two relay protection devices respectively; determines the occurrence of a fault; for each relay protection device, calculates the voltage fault component and the current fault component according to the voltage sample and the current sample; determines the voltage fault modulus and the current fault modulus according to the voltage fault component and the current fault component; determines the relative direction of the fault corresponding to the relay protection device according to the voltage fault modulus and the current fault modulus; determines that the fault is located between the two relay protection devices according to the relative direction of the faults of the two relay protection devices, and sends protection instructions to the two relay protection devices. It is not affected by factors such as the weak feedback characteristics of the inverter-type new energy, changes in power supply impedance, and inconsistency of positive and negative sequence impedances, and is not affected by the fault starting angle, fault location, and transition resistance. The required sampling rate can match the sampling rate that can be provided by current commercial relays, and a higher sampling rate is not required, thereby improving the reliability of fault protection for the inverter-type power supply transmission line.

[0119] The method of the present application is specifically described through several specific examples.

[0120] In the electromagnetic transient simulation software PSCAD / EMTDC, Figure 5 In the inverter power transmission line system shown, the equivalent power is boosted to 35kV by the box transformer for collection. The station capacity is 200MW, the voltage level of the transmission line is 330kV transmission line, the transmission line length is 40km, and after transmission, it is boosted to 750kV by the transformer and connected to the system side. The sampling rate of the protection device is 10kHz, and the algorithm data window length of the protection scheme is 2ms.

[0121] Example 1

[0122] like Figure 5 As shown, at the midpoint f1 between the busbar S and the busbar P, a phase A (ie, phase a) grounding fault occurs, the fault starting angle is 45 degrees, and the transition resistance is 100Ω.

[0123] Get relay protection device R S Voltage samples (such as Figure 6 as shown) and current samples (as Figure 7 As shown), obtain the relay protection device R P Voltage samples (such as Figure 8 as shown) and current samples (as Fig. 9 shown).

[0124] According to the relay protection device R S The current sample and formula (1) are used, and the preset discrimination threshold ε is set to 0.4. When k=4, |Gradient(4)|=1.3>ε, and it is determined that a fault occurs.

[0125] For relay protection device R S , according to R S The corresponding voltage sample and current sample are used to determine R through formula (2). S The corresponding voltage fault component (such as Fig.10 ) and the current fault component (as Fig.11 According to R S The corresponding voltage fault component and current fault component are determined by formula (3) and formula (4) to determine R S The corresponding voltage fault modulus and current fault modulus; according to R S The corresponding voltage fault modulus and current fault modulus are determined by formula (5) to determine the relay protection device R S The corresponding adaptive transient energy C S =-1011.2369<0, determine the relay protection device R S The corresponding fault relative direction is the positive direction, that is, the fault occurs in the relay protection device R S on the right side.

[0126] For relay protection device R P , according to R P The corresponding voltage sample and current sample are used to determine R through formula (2). P The corresponding voltage fault component (such as Fig.12 ) and the current fault component (as Fig.13 According to R P The corresponding voltage fault component and current fault component are determined by formula (3) and formula (4) to determine R P The corresponding voltage fault modulus and current fault modulus; according to R P The corresponding voltage fault modulus and current fault modulus are determined by formula (5) to determine the relay protection device R P The corresponding adaptive transient energy C P =-5845.3312<0, determine the relay protection device R P The corresponding fault relative direction is the positive direction, that is, the fault occurs in the relay protection device R P on the left side.

[0127] According to the relative directions of the faults of the two relay protection devices, it can be determined that the fault occurred in the relay protection device R S On the right side, the relay protection device RP On the left side of , it can be determined that the fault is between the two relay protection devices, and protection instructions are sent to the two relay protection devices.

[0128] Example 2

[0129] like Figure 5 As shown, a phase A (i.e., phase a) grounding fault occurs between bus R and bus T, 2 km away from bus R, i.e., at f2. The fault starting angle is 90 degrees, and the transition resistance is 100Ω.

[0130] Continue with the steps of the above embodiment to determine the relay protection device R S The corresponding adaptive transient energy C S =-51943.1972<0, determine the relay protection device R S The corresponding fault relative direction is the positive direction, that is, the fault occurs in the relay protection device R S to the right; determine the relay protection device R P The corresponding adaptive transient energy C P =4989.4153>0, determine the relay protection device R P The corresponding fault relative direction is the opposite direction, that is, the fault occurs in the relay protection device R P on the right side.

[0131] According to the relative directions of the faults of the two relay protection devices, it can be determined that the fault occurred in the relay protection device R S On the right side, the relay protection device R P On the right side of , it can be determined that the fault is not located between the two relay protection devices, and no protection command is sent to the two relay protection devices.

[0132] Other examples are summarized in Table 1 below.

[0133] Table 1

[0134]

[0135] It can be seen from Table 1 that the present application is not affected by the size of the fault starting angle, the fault location (whether it is in the near zone), and the size of the transition resistance.

[0136] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in this embodiment is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in this embodiment or the accompanying drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0137] like Fig.14 As shown, the embodiment of the present application also provides an inverter type power supply transmission line fault protection device. The device includes: an acquisition module 1401, a fault identification module 1402, a direction determination module 1403 and an indication module 1404.

[0138] The acquisition module 1401 is used to respectively acquire voltage samples and current samples of two relay protection devices.

[0139] The fault identification module 1402 is used to determine whether a fault occurs.

[0140] The direction determination module 1403 is used to calculate the voltage fault component and the current fault component for each relay protection device based on the voltage sample and the current sample; determine the voltage fault modulus and the current fault modulus based on the voltage fault component and the current fault component; and determine the relative fault direction corresponding to the relay protection device based on the voltage fault modulus and the current fault modulus.

[0141] The indication module 1404 is used to determine that the fault is located between the two relay protection devices according to the relative directions of the faults of the two relay protection devices, and send protection instructions to the two relay protection devices, wherein the protection instructions are used to instruct the relay protection devices to perform protection tripping.

[0142] The beneficial effects and specific implementation methods of the device embodiment can be referred to the aforementioned method embodiment, and will not be described in detail here.

[0143] Some modules in the apparatus described in the present application can 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, classes, etc. that perform specific tasks or implement specific abstract data types. The present application can also be practiced in distributed computing environments, in which tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0144] The devices or modules described in the above application embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described in various modules according to their functions. When implementing the embodiments of the present application, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, the module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0145] The methods, devices or modules described in this application can be implemented in the form of computer-readable program codes. The controller can be implemented in any appropriate manner. For example, the controller can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program codes (such as software or firmware) that can be executed by the (micro) processor, logic gates, switches, application-specific integrated circuits (English: Application Specific Integrated Circuit; Abbreviation: ASIC), programmable logic controllers and embedded microcontrollers. Examples of controllers include but are not limited to the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20 and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in a purely computer-readable program code, the controller can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, this controller can be considered as a hardware component, and the devices included in it for implementing various functions can also be regarded as structures within the hardware component. Or even, the means for realizing various functions may be regarded as both a software module for realizing the method and a structure within a hardware component.

[0146] An embodiment of the present application further provides a device, comprising: a processor; a memory for storing processor executable instructions; when the processor executes the executable instructions, the method described in the embodiment of the present application is implemented.

[0147] The embodiments of the present application also provide a non-volatile computer-readable storage medium on which a computer program or instruction is stored. When the computer program or instruction is executed, the method described in the embodiments of the present application is implemented.

[0148] In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist independently, or two or more modules may be integrated into one module.

[0149] The above storage media include but are not limited to random access memory (RAM), read-only memory (ROM), cache, hard disk (HDD) or memory card. The memory can be used to store computer program instructions.

[0150] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary hardware. Based on such an understanding, the technical solution of the present application can be essentially or partly contributed to the prior art in the form of a software product, or it can be reflected in the implementation process of data migration. The computer software product can be stored in a storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a mobile terminal, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0151] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. All or part of this application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, mobile communication terminals, multi-processor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc.

[0152] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for protecting an inverter power outgoing line from faults, characterized in that: include: respectively obtaining voltage samples and current samples of two relay protection devices; Determine that a fault has occurred; For each relay protection device, a voltage fault component and a current fault component are calculated based on the voltage sample and the current sample; Determining a voltage fault modulus and a current fault modulus according to the voltage fault component and the current fault component; Determining a relative fault direction corresponding to a relay protection device according to the voltage fault modulus and the current fault modulus; According to the relative directions of the faults of the two relay protection devices, it is determined that the fault is located between the two relay protection devices, and a protection instruction is sent to the two relay protection devices, wherein the protection instruction is used to instruct the relay protection devices to perform a protection trip.

2. The method according to claim 1, characterized in that The determining that a failure occurs includes: According to the current sample and the fault discrimination formula, when the current sample satisfies the fault discrimination formula, determining that a fault occurs; The fault discrimination formula is shown in formula (1): In formula (1), k represents the index number of the current sample, ε is the preset discrimination threshold, Δi(m) represents the current fault component corresponding to the mth current sample, and Δi(n) represents the current fault component corresponding to the nth current sample.

3. The method according to claim 1, characterized in that The step of calculating the voltage fault component and the current fault component according to the voltage sample and the current sample comprises: Taking the time corresponding to the occurrence of the fault as the starting time, determining the voltage fault component and the current fault component according to the fault component calculation formula, the voltage sample and the current sample; The fault component calculation formula is shown in formula (2): In formula (2), Δu(t) represents the voltage fault component at time t, u(t) represents the voltage at time t, u(tT) represents the voltage at time tT, T represents the fundamental wave period, Δi(t) represents the current fault component at time t, i(t) represents the current at time t, and i(tT) represents the current at time tT.

4. The method according to claim 1, characterized in that: The determining of the voltage fault modulus and the current fault modulus according to the voltage fault component and the current fault component comprises: Determine the voltage fault modulus according to the voltage fault component and the voltage fault modulus determination formula; determine the current fault modulus according to the current fault component and the current fault modulus determination formula; The voltage fault modulus determination formula is shown in formula (3): In formula (3), Δu α represents the α modulus of the voltage fault component after phase modulus transformation, i.e., the voltage fault modulus; Δu a Indicates the a-phase component of the voltage fault component; Δu b Represents the b-phase component of the voltage fault component; The current fault modulus determination formula is shown in formula (4): In formula (4), Δi α represents the α modulus of the voltage fault component after phase modulus transformation, that is, the current fault modulus; Δi a Indicates the a-phase component of the current fault component; Δi b Represents the b-phase component of the current fault component.

5. The method according to claim 1, characterized in that The determining the relative fault direction corresponding to the relay protection device according to the voltage fault modulus and the current fault modulus includes: Determine the adaptive transient energy according to the voltage fault modulus and the current fault modulus and the adaptive transient energy calculation formula; determine the relative direction of the fault corresponding to the relay protection device according to the positive and negative of the adaptive transient energy; The adaptive transient energy calculation formula is shown in formula (5): C=||Δu α ||·||Δi α ||E(5)In formula (5), C represents the adaptive transient energy; Δu α The α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the voltage fault modulus; Δi α represents the α modulus of the three-phase component of the voltage fault component after phase modulus transformation, that is, the current fault modulus; E represents the transient energy, Where i represents the index number of the voltage fault component and the current fault component, and N represents the total number of sampling points within the data window duration.

6. The method according to claim 2, characterized in that The preset discrimination threshold ε is determined according to the sensitivity requirement of the application scenario.

7. The method according to claim 1, characterized in that The step of determining that the fault is located between the two relay protection devices according to the relative directions of the faults of the two relay protection devices comprises: When the relative directions of the faults of the two relay protection devices are both positive directions, it is determined that the fault is located between the two relay protection devices.

8. An inverter type power supply output line fault protection device, characterized in that: include: An acquisition module, used for respectively acquiring voltage samples and current samples of two relay protection devices; A fault identification module, used to determine if a fault has occurred; A direction determination module, for calculating a voltage fault component and a current fault component for each relay protection device according to a voltage sample and a current sample; Determining a voltage fault modulus and a current fault modulus according to the voltage fault component and the current fault component; Determining a relative fault direction corresponding to a relay protection device according to the voltage fault modulus and the current fault modulus; The indication module is used to determine that the fault is located between the two relay protection devices according to the relative directions of the faults of the two relay protection devices, and send a protection instruction to the two relay protection devices, wherein the protection instruction is used to instruct the relay protection devices to perform a protection trip.

9. A device for executing an inverter type power supply transmission line fault protection method, characterized in that: include: processor; a memory for storing processor-executable instructions; When the processor executes the executable instructions, the method according to any one of claims 1 to 7 is implemented.

10. A non-volatile computer-readable storage medium, characterized in that: The device comprises a computer program or an instruction for storing the computer program or the instruction, which, when executed, enables the method according to any one of claims 1 to 7 to be implemented.

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