Method for determining damaged phases and type of damage of electricity transmission line

Abstract

FIELD: electrical engineering.SUBSTANCE: invention can be used in relay protection and automation of high and ultra-high voltage lines, in particular, in single-phase automatic reclosing devices for selecting a damaged phase and determining the type of short circuit. According to the method, three-phase voltages and currents are supplied to the inputs of the phase selector, which are fed to the inputs of the filters of symmetrical components of voltage and current, respectively, the groups of characteristic values created by the characteristic value generation unit are supplied to the corresponding groups of inputs of the damage type classifier unit, which generates a logical signal of the damage type and damaged phases at the corresponding output of the phase selector based on determining the values of the characteristic values.When classifying the type of damage, the possibility of using the currents and voltages of the previous mode is taken into account, for which a control signal from the circuit breaker control automation is fed to the input of the damage type classifier. Before the implementation of the method begins, the values of the functional dependencies of the ratio of currents and voltages in the direct, reverse and zero sequences are obtained and stored in the memory block by simulation modelling, the values of the functional dependencies of the ratio of currents and voltages in the direct, reverse and zero sequences, and the values of the symmetrical components of the voltage of the direct, reverse and zero sequences generated by the filter are used to generate characteristic quantities in the characteristic quantity generation unit. From the output of the damage type classifier unit, along with signals about the type of damage, a signal about the damaged phase or phases is generated.EFFECT: simplifying the method for determining damaged phases and the type of damage to a power transmission line while maintaining a high recognition capability for various types of short circuits.1 cl, 7 dwg

Description

[0001] The invention relates to electrical engineering and can be used in relay protection and automation of high and ultra-high voltage lines, in particular, in single-phase automatic reclosing devices for selecting a damaged phase and determining the type of short circuit.

[0002] A method for determining damaged phases and damage zones of a power transmission line is known [Russian Federation Patent for Invention No. 2037246, IPC H02H 3 / 40, H02H 3 / 26, G01R 31 / 08, published 06 / 09 / 1995].According to the method for determining damaged phases and the damage zone of a power transmission line by measuring voltages, currents, and their components at the beginning of the line and converting the measured quantities into three reactive parameters, the measured quantities are preliminarily converted into first quantities corresponding to the voltages at the beginning of the line, second quantities corresponding to the voltages at the end of the monitored zone of the undamaged line, and into third reference quantities, the first reactive parameter is formed as the mutual reactive power of the first and third quantities, the second reactive parameter as the mutual reactive power of the second and third quantities, the third reactive parameter as the mutual reactive power of the first and second quantities, the sign of the third parameter is compared with the signs of the first and second parameters and the damage is recorded in the monitored zone if the signs of the first and third parameters coincide and are opposite to the sign of the second parameter.

[0003] The disadvantage of the known method for determining damaged phases and damage zones of a power line is the low recognition ability in distinguishing between different types of short circuits and determining damaged phases.

[0004] A method is known for determining a special phase during a short circuit to ground of a power transmission line [Patent of the Russian Federation for invention No. 2031506, IPC H02H 3 / 16, H02H 3 / 26, H02H 3 / 42, published. [20.03.1995], in which, by forming a reference signal proportional to the zero-sequence current, three main signals proportional to the negative-sequence currents of different phases of the power transmission line, determining the angular zone of the reference signal relative to the main signals, three mutual reactive powers are determined between each of the main and the reference signal, the reactive powers and three additional signals are converted, each of the additional signals is summed with a portion of the additional signal of the leading phase, thereby forming three total signals, a pair of total signals is identified in which the sign of the total signal of the leading phase is positive, and the lagging phase is negative, and the one to which the said lagging signal corresponds is accepted as a special phase.

[0005] The disadvantage of the known method for determining a special phase during a ground fault in a power line is the low recognition ability in distinguishing between different types of short circuits and determining damaged phases.

[0006] The closest technical solution is the method for determining damaged phases and the type of damage to a power transmission line [Russian Federation Patent for Invention No. 2790618, IPC H02H 3 / 26, published 02 / 28 / 2023, Bulletin No. 7], according to which a phase selector is installed on each phase of the power transmission line, three-phase voltages and currents are supplied to the analog inputs of each phase selector, which are fed to the inputs of the filters of symmetrical components of voltage and current, respectively, the currents of direct, negative and zero sequences generated by the filter of symmetrical components are normalized relative to the positive sequence current, for this purpose, first, the amplitude of the positive sequence current is determined by the module determination unit, and then scaled currents of direct, negative and zero sequences are formed in the scaling unit,the characteristic value groups generated by the characteristic value generation unit are fed to the corresponding input groups of the fault type classifier unit, which recognizes the fault type and the faulty phases and generates a logical fault type signal at the corresponding output of the phase selector by establishing the position of the points, the coordinates of which are determined by the characteristic values ​​of the groups, relative to the response characteristics, while in order to differentiate between phase-to-phase faults and short circuits to ground, the scaled zero sequence current modulus is compared with the setting in the threshold element, and if it exceeds the setting and leads to the operation of the threshold element, then it is assumed that a short circuit to ground has occurred, otherwise - an interphase fault.

[0007] According to the proposal, the characteristic quantities of the groups are created in the characteristic quantities generation unit based on the scaled currents of the symmetrical components, the arguments of which are determined relative to the complex amplitude of the positive sequence voltage, for this purpose, the initial phase of the positive sequence voltage arriving at its input from the corresponding output of the symmetrical voltage component filter is first determined by the block for determining the argument of the complex electrical quantity, and then, in the phase-shifting unit, the arguments of all scaled symmetrical components are reduced by the value of the initial phase of the positive sequence voltage, the response characteristics of the phase selector are formed in the block of damage type classifiers in a multidimensional space in the form of hypersurfaces that enclose points, the coordinates of which are determined by the characteristic quantities of the corresponding group, consistent with the type of damage and the damaged phases,wherein the coordinates of the points in the formation of the hypersurfaces of the response characteristics are obtained by simulating the modes of the controlled power transmission line for all types of damage, the block of damage type classifiers consists of classifiers, the groups of inputs of which are the corresponding groups of inputs of the block, and a logic block that processes the set of logical signals arriving at the input from the outputs of the classifiers taking into account the signal arriving from the output of the said threshold element, and makes a decision on the type of damage and on the indicator that the phase of the selector is a special phase, and forms logical signals of the types of damage at the outputs of the phase selector, wherein the type of three-phase short circuit on the power transmission line is established by the phase selector by analyzing the logical signals of interphase short circuits arriving from the outputs of other voters to its logical inputs, and the logical signal of the interphase short circuit from its output,wherein the signal of occurrence of a three-phase short circuit at the output of the selector is generated by a three-phase short circuit detection unit, the first two inputs of which are connected to the logical inputs of the phase selector, and the third - to the output of the logical signal of the phase-to-phase short circuit of its phase selector, and the type of three-phase short circuit is established upon the operation of the logical signals of the phase-to-phase short circuit of two or more phase selectors.

[0008] The disadvantage of the prototype method is the complexity of technical implementation in determining damaged phases and the type of damage to the power line.

[0009] The technical result consists in simplifying the method for determining damaged phases and the type of damage to a power transmission line while maintaining a high recognition ability in relation to various types of short circuits.

[0010] When determining the damaged phase of power transmission lines (PTL), operations with observed currents and voltages are preceded by an analysis of a priori information about the structure and parameters of the network, the purpose of which is to obtain functional relationships inherent in the place expected short circuit (SC). Fig. 1.a shows a model of the current network mode, where And - vectors of currents and voltages at the observation point, And - vectors of currents and voltages at the location of the short circuit, - vector of line currents at the location before the short circuit. Active multi-pole models a network external to the line. In addition, if information about the previous line mode is available, current and voltage vectors are also available. And The presence of a pre-damage regime opens up the possibility of identifying emergency components

[0011] (1)

[0012] activated by short-circuit current source , operating from an unknown location .

[0013] The balanced line model is represented by a set of two-wire zero-sequence channels and centered (non-zero) phase quantities, defined as the difference between phase quantities and zero-sequence components

[0014] (2)

[0015] The latter, in turn, are represented as the sum of the components of the direct and reverse sequence

[0016] (3)

[0017] If the zero sequence was not observed in the previous mode, then it belongs to the emergency components of phase quantities

[0018] (4)

[0019] and the two-wire models of zero sequence (Fig. 1.b) and centered fault components (Fig. 1.c) are each activated by a single source. The rest of the network is represented in the models (Fig. 1.b and 1.c) by passive three-terminal networks And The models (Fig. 1.b) are characterized by zero-sequence parameters, while those in Fig. 1.c are characterized by positive-sequence parameters. If the preceding mode is symmetrical, then the negative sequence is directly included in the centered emergency components together with the positive-sequence emergency component.

[0020] (5)

[0021] The two-wire negative sequence model has the same passive parameters as the model in Fig. 1.c.

[0022] Two network parameters related to the fault location in each of the two-wire models are of particular interest: the internal network resistances presented relative to the fault location equivalent zero- and positive-sequence generators

[0023] (6)

[0024] (7)

[0025] and also the relationship between the currents before and at the short circuit location

[0026] (8)

[0027] (9)

[0028] The task of a priori network analysis is to determine the coordinate functions , ; , , Where is interpreted as the location of the suspected damage. The subsequent task of determining the damaged phase is reduced to the transformation of the components of the observed quantities And in currents and voltages The transformation is carried out using algorithmic models of undamaged power transmission with specific parameters And positive and zero sequence (Fig. 2). Operations with negative sequence values ​​(Fig. 2.g) are provided for the case when emergency components are unavailable, for example, when voltage is supplied to a damaged power line.

[0029] As an example, Fig. 3 shows the coordinate functions (6) - (9) of a 330 kV transmission line with a length of with specific parameters of direct and zero sequence And with the same parameters of the transmitting and receiving systems: Coordinate functions connect the output values ​​of algorithmic models with the currents of the expected short circuit

[0030] (10)

[0031] (11)

[0032] (12)

[0033] (13)

[0034] Current (10) - (13) and voltage functions

[0035] (14)

[0036] provide an answer to the question at what value of the coordinate the boundary conditions of one of the types of short-circuit are met.

[0037] Fig. 4 shows examples of ground faults in a location with transition resistance at And with phase-to-phase short circuit and the angle of transmission of the line , as well as the equality of the modules of the sources of the transmitting and receiving systems. The passive parameters are the same as for the circuit in Fig. 3. Dependencies of the modules from coordinate (Fig. 4) demonstrate two facts. First, in damaged phases, currents increase monotonically from the beginning of the line to its end. Second, in undamaged phases, currents from the beginning of the line to the short-circuit point decrease to zero and then increase monotonically, which is sufficient to identify the damaged phase.

[0038] In the absence of emergency components of electrical quantities, it is impossible to determine the functions of the centered components , applying operations (11). As a consequence, it will not be possible to determine the functions as the sum (12). However, it is possible to express the expected fault currents through the components (10), (13) of the zero and negative sequences, using the boundary conditions of the corresponding type of short circuit. Thus, for a single-phase short circuit (Fig. 4.b) the boundary conditions are valid

[0039] (15)

[0040] (16)

[0041] (17)

[0042] Accordingly, in case of two-phase short circuit (Fig. 4.c), in a particular case ,

[0043] (18)

[0044] (19)

[0045] (20)

[0046] (21)

[0047] (22)

[0048] where - phase rotation coefficient.

[0049] Of the five coordinate functions (10) - (14), two, namely (11), (12), are inaccessible this time. The remaining functions , And are designed to ensure recognition of damaged phases during short circuits And , Where - the lagging phase symbol, based on the boundary conditions (15) - (17) for and (18) - (22) for .

[0050] Single-phase phase short circuit identified by the condition

[0051] (23)

[0052] which allows you to identify the damaged phase . The final assessment is given by condition (16) for the phase (Fig. 5). The illustrations in Fig. 5 were obtained for the unloaded line switching mode, the model of which was previously shown in Fig. 4.

[0053] Boundary conditions (18) - (22) do not create such prerequisites for recognizing two faulty phases. A more complex approach remains, leading to the identification of faulty phases through fault location based on the reactive power criterion of the two phases, in this case And , with the definition of the current function And

[0054] (24)

[0055] where - presumably an undamaged phase. If the assessment is determined , which meets condition (24), then at the same time the hypothesis about phase damage will be confirmed And (Fig. 6).

[0056] The objective of the invention is to simplify the method for determining damaged phases and the type of damage to a power transmission line while maintaining a high recognition ability in relation to various types of short circuits.

[0057] The stated task is achieved by the method of determining the damaged phases and the type of fault in a power transmission line, according to which three-phase voltages and currents are supplied to the inputs of the phase selector, which are fed to the inputs of the filters of the symmetrical components of voltage and current, respectively, the groups of characteristic values ​​​​created by the characteristic value generation unit are supplied to the corresponding groups of inputs of the fault type classifier unit, which recognizes the fault type and the damaged phases and generates a logical signal of the fault type and the damaged phases at the corresponding output of the phase selector based on the establishment of the values ​​​​of the characteristic values, the characteristic values ​​​​are formed in the characteristic value generation unit based on the currents of the symmetrical components, the response characteristics of the phase selector are formed in the fault type classifier unit,values ​​are obtained by simulating the modes of the controlled power transmission line, which are used to determine the type of damage, the block of classifiers of the type of damage consists of classifiers, the groups of inputs of which are the corresponding groups of inputs of the block, and a logic block, which processes the set of logical signals received at the input from the outputs of the classifiers, makes a decision on the type of damage and generates logical signals of the types of damage at the outputs of the phase selector, while the type of three-phase short circuit on the power transmission line is established by the phase selector taking into account the analysis of logical signals of interphase short circuits.

[0058] When classifying the type of damage, the possibility of using the currents and voltages of the previous mode is taken into account, for which purpose a control signal from the circuit breaker control automation is fed to the input of the damage type classifier; before starting the implementation of the method, by means of simulation modeling, the values ​​of the functional dependencies of the ratio of currents and voltages along the direct (reverse) and zero sequences are obtained and stored in the memory block according to the expressions

[0059]

[0060]

[0061] where , - zero-sequence voltage and current at the expected location of the fault, , - voltage and current of the negative sequence at the supposed location of the phase fault , , - zero and negative phase sequence currents to the short-circuit location. The values ​​of the functional dependencies of the current and voltage ratios for the positive, negative, and zero sequences, as well as those generated by the filter of symmetrical components of the voltage of the positive, negative, and zero sequences, are used to generate characteristic quantities in the characteristic quantity generation block. The output of the fault type classifier block, along with signals on the fault type, produces a signal on the damaged phase(s).

[0062] Fig. 1 shows models of an electrical network with a damaged power transmission line: a - current mode; b - zero sequence; c - centered (non-zero) components.

[0063] Fig. 2 shows models of two-wire channels of a power transmission line: a - zero sequence; b, c - centered components; d - negative sequence.

[0064] Fig. 3 shows the models and coordinate functions of the power transmission line: a - passive model of the line; b - model for determining the parameters of the location in, g - coordinate functions of a given line.

[0065] Fig. 4 shows the models and dependencies of the modules of the expected fault currents on its coordinates during a ground fault at a location : a - simulation model of the network; b, c - short circuit models at , ; g, d - dependencies under corresponding short circuits.

[0066] Fig. 5 illustrates the principles of determining the type and location of damage without a preceding mode when : a - simulation model of switching on a line for a short circuit, b - dependence of the current modules of the supposed fault location on their coordinates, c - determination of the location of a single-phase short circuit.

[0067] Fig. 6 characterizes the explanations for determining the type and location of damage without a preceding mode during a two-phase short circuit to ground .

[0068] Fig. 7 shows a structural diagram of a device (phase selector) that implements the proposed method for determining damaged phases and the type of damage to a power transmission line.

[0069] The device (Fig. 7) includes: filters for symmetrical components of voltage 1 and current 2; a characteristic value generation unit 3; a memory unit 4; a damage type classifier unit 5; a signal for automatic switch control 6.

[0070] The device (phase selector) implementing the method for determining damaged phases and the type of damage to a power transmission line (Fig. 7) operates as follows.

[0071] Before the device starts functioning (Fig. 7), a simulation modeling of a section of the electrical network (e.g., Fig. 4.a) is performed in order to obtain the functional dependencies of the current and voltage ratios for the direct (reverse) and zero sequences corresponding to expressions (6)-(9) and depending on the fault location. The results of the simulation modeling in the form of values ​​of the functional dependencies are entered into block 4 of the device memory (Fig. 7).

[0072] During the operation of the device (Fig. 7), the values ​​of the phase voltages, respectively, are sent to the inputs of the filters of symmetrical components of voltage 1 and current 2 , , and currents , , As a result of the operation of filters 1 and 2, symmetrical voltage components appear at their outputs. , , and currents , , , which are fed to the inputs of the characteristic value generation unit 3. Additionally, the results of the simulation modeling are fed to the input of unit 3 from the output of memory unit 4, which are necessary for generating characteristic values, thanks to which the damaged phases and the type of damage to the power transmission line are determined.

[0073] Block 3 calculates the dependencies for various probable short-circuit points. Such points are located along the power transmission line and correspond to the dependencies according to expressions (10)-(14) for determining the damaged phases and the type of fault on the power transmission line in the presence of a preceding mode, and according to expressions (15)-(24) in the absence of a preceding mode. The conditions without a preceding mode are typical for the case of automatic (ARC - automatic reclosing) or manual closing of the power transmission line with fault. Examples of the generated dependencies are illustrated by Fig. 4.g, Fig. 4.d, Fig. 5.b, Fig. 5.c, Fig. 6.

[0074] Arrays of characteristic value dependencies from the outputs of block 3 are fed to the inputs of block 5 of the fault mode classifiers. Block 5 of the fault mode classifiers consists of classifiers whose input groups are the corresponding input groups of block 5. Block 5 of the fault mode classifiers also includes a logic block that processes the set of logical signals received at the input from the classifier outputs and generates a decision on the fault mode and the faulted phase(s) and generates logical signals for the fault modes at the phase selector outputs. A signal from the circuit breaker control automation is sent to the control input of block 5 to make a decision on the fault mode and the faulted phase(s) depending on the presence or absence of the previous mode.Thus, a signal from the circuit breaker's automatic control output is sent to the control input of unit 5 in the event of automatic or manual activation of a faulty power line. Based on this signal, the logic unit within unit 5 analyzes the outputs of the classifiers that process the sequences of characteristic quantities related to the absence of the preceding mode.

[0075] The classifiers of Block 5 analyze the dependencies of the characteristic quantities corresponding to expressions (10)-(14) for determining the damaged phases and the type of fault in the power transmission line in the presence of a preceding mode, and according to expressions (15)-(24) in the absence of a preceding mode. In the presence of a preceding mode, the currents in the damaged phases monotonically increase from the beginning of the line to its end, while in the undamaged phases, the currents from the beginning of the line to the short-circuit location decrease to zero and then monotonically increase. For example, Fig. 4.g shows the dependencies of the characteristic quantities for the case of a two-phase short-circuit , and in Fig. 4.d - for single-phase . In the absence of a previous mode, the dependences of the characteristic values ​​on the possible location of damage (10), (13), (14) are used, which ensure the recognition of damaged phases during a short circuit And taking into account the boundary conditions (15) - (17) for and (18) - (22) for , Where - lagging phase symbol.

[0076] Single-phase phase short circuit is identified by condition (23), which allows the damaged phase to be detected . The final assessment is given by condition (16) for the phase (Fig. 5). To recognize two damaged phases, the reactive power of the two phases is used as the characteristic value dependence, for example, And with the definition of the current function And and meeting criterion (24), where - presumably an undamaged phase. If the assessment is determined , which meets this condition, then at the same time the hypothesis about phase damage will be confirmed And (Fig. 6).

[0077] Logical signals are sent from the classifier outputs of block 5 to the inputs of the logic block, which is also part of block 5. The logic block processes the set of logical signals received at the input from the classifier outputs, based on which a decision is made on the type of fault, the faulted phase(s), and also generates logical signals of the fault types and faulted phases at the device outputs (Fig. 7). In particular, the signal from the device output (Fig. 7), characterizing a three-phase short circuit on the power line, is sent taking into account the presence of logical signals of both phase-to-phase and single-phase short circuits at the logic block inputs.

[0078] To substantiate the advantages of the proposed method for identifying faulty phases and the type of fault on a power line, we compare the hardware costs of implementing the device (Fig. 7) with those of a device implementing the prototype method. Thus, the prototype method involves installing faulty phase selectors in each of the three phases A, B, and C. In contrast, the device (Fig. 7) is common to all three phases.

[0079] Thus, the proposed method makes it possible to achieve the objective of the invention, which consists in simplifying the method for determining damaged phases and the type of damage to a power transmission line while maintaining a high recognition ability in relation to various types of short circuits.

Claims

A method for determining damaged phases and the type of fault in a power transmission line, including supplying three-phase voltages and currents to the inputs of a phase selector, which are fed to the inputs of filters of symmetrical components of voltage and current, respectively, the groups of characteristic quantities generated by the characteristic quantity generation unit are supplied to the corresponding groups of inputs of the fault type classifier unit, which recognizes the fault type and damaged phases and generates a logical signal of the fault type and damaged phases at the corresponding output of the phase selector based on the establishment of the values ​​of characteristic quantities, the characteristic quantities are generated in the characteristic quantity generation unit based on the currents of symmetrical components, the response characteristics of the phase selector are generated in the fault type classifier unit, and are obtained by simulating the modes of the monitored power transmission line,which are used in determining the type of damage, the block of damage type classifiers consists of classifiers, the input groups of which are the corresponding groups of block inputs, and a logic block that processes the set of logical signals coming to the input from the classifier outputs, makes a decision on the type of damage and generates logical signals of the types of damage at the outputs of the phase selector, wherein the type of three-phase short circuit on the power transmission line is established by the phase selector taking into account the analysis of logical signals of phase-to-phase short circuits, characterized in that when classifying the type of damage, the possibility of using currents and voltages of the previous mode is taken into account, for which purpose a control signal from the circuit breaker control automation is fed to the input of the damage type classifier,Before starting the implementation of the method, by means of simulation modeling, the values ​​of the functional dependencies of the ratio of currents and voltages in the direct, reverse and zero sequences are obtained and stored in the memory block according to the expressions, Where , – zero-sequence voltage and current at the expected location of the fault, , – voltage and current of the negative sequence at the supposed location of the phase fault , , – zero and negative phase sequence currents to the place of short circuit; The values ​​of the functional dependencies of the ratios of currents and voltages in the direct, reverse and zero sequences, as well as those generated by the filter of symmetrical components of the voltage of the direct, reverse and zero sequences, are used to form characteristic quantities in the characteristic quantity formation block, which are fed to the block of damage type classifiers; from the output of the block of damage type classifiers, along with signals about the type of damage, a signal about the damaged phase or phases is output.

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