Synchronous verification method and system for power transmission line, storage medium and equipment

Abstract

The embodiment of the invention discloses a synchronous verification method for a power transmission line, and the method comprises the steps: determining the corresponding protection differential current isdiffA / B / C, and the break variables [delta] imA / B / C and [delta] inA / B / C of the currents at the two sides according to the voltages and currents at the two sides of the power transmission line; determining whether to perform synchronous verification or not according to a comparison relationship between the protection differential current ridiffA / B / C and a power transmission line differential current working constant value and between the break variables delta imA / B / C and delta inA / B / C of the currents on the two sides and a break variable current starting constant value; if synchronous verification is carried out, voltages on the two sides of the power transmission line are calculated to the same point of the power transmission line, and a first voltage and a second voltage are obtained; and determining whether synchronous verification is completed or not according to the ratio of the first voltage to the second voltage and the angle difference. According to the invention, through the voltage and current information of the two sides of the power transmission line, the ratio and the angle difference of the voltage are comprehensively considered, the synchronous verification judgment is carried out, and the accuracy, the reliability and the real-time performance of the synchronous verification of the power transmission line can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a synchronization verification method, system, storage medium and equipment for transmission lines. Background Art

[0002] In the power system, the synchronization verification of the transmission line is crucial to ensure the correct operation of the current differential protection. As the main protection mode of high-voltage transmission line relay protection, the reliability of the current differential protection directly depends on the synchronization accuracy of the data on both sides.

[0003] However, although traditional transmission line synchronization verification methods, such as the ping-pong synchronization method, can meet the synchronization requirements to a certain extent, they have obvious limitations; the premise of this method is that the communication receiving and transmitting routes of the protection devices on both sides must be consistent; in actual applications, if the communication equipment selects different routes, or the communication network is blocked due to sudden traffic and other reasons, resulting in a large error in the data calculated by a ping-pong synchronization, it will directly lead to a large error in the aligned sampling data, and then there is a risk of false protection operation.

[0004] With the continuous development of the power system, the accuracy and real-time requirements for transmission line synchronization verification are becoming higher and higher. The traditional ping-pong synchronization method can no longer meet these requirements. Therefore, it is necessary to find a more accurate and reliable synchronization verification method. Summary of the invention

[0005] Based on this, it is necessary to propose a synchronization verification method for transmission lines to address the above problems.

[0006] A synchronization verification method for a power transmission line, the method comprising the following steps:

[0007] According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0008] According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0009] If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage;

[0010] Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

[0011] In the above scheme, the protection differential current i is determined according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C , specifically including:

[0012] Collect the voltage u on both sides of the transmission line mA / u mB / u mC 、u nA / u nB / u nC and current i mA / i mB / i mC 、i nA / i nB / i nC ,

[0013] Determine the protection differential current i according to the voltage and current on both sides of the transmission line diffA / B / C :

[0014] i diffA / B / C =|i mA / B / C +i nA / B / C |

[0015] Determine the sudden change Δi of the current on both sides of the transmission line according to the voltage and current on both sides of the transmission line mA / B / C , Δi nA / B / C :

[0016] Δi mA / B / C =|i mA / B / C.t1 -i mA / B / C.t0 |

[0017] Δi nA / B / C =|i nA / B / C.t1 -i nA / B / C.t0 |

[0018] Wherein, t1 represents the current electrical quantity information, and t0 represents the electrical quantity information at the moment when t1 minus the preset time is subtracted.

[0019] In the above scheme, the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden current starting value determines whether to perform synchronization verification, including:

[0020] Preset differential current action setting value I on both sides of the transmission line set And the sudden current starting value I qd ;

[0021] If i diffA / B / C >I set or Δi mA / B / C >I qd or Δi nA / B / C >I qd , then no synchronization check is performed;

[0022] If i diffA / B / C <I set And Δi mA / B / C <I qd , Δi nA / B / C <I qd , then perform synchronization verification.

[0023] In the above scheme, if the synchronization verification is performed, the voltages on both sides of the transmission line are respectively calculated to the same point of the transmission line to obtain the first voltage and the second voltage, which specifically includes:

[0024] The default transmission line is MN, and its inductance and capacitance per unit length are L0 and C0 respectively:

[0025]

[0026] In the formula, τ = l / v represents the transmission time of electromagnetic waves along the entire length of the line. It represents wave impedance;

[0027] Using the voltage and current measurements at the N terminal, the voltage and current at the M terminal are calculated;

[0028] Using the voltage and current measurements at the M terminal, the voltage and current at the N terminal are calculated;

[0029] The voltage collected at the M and N sides of the transmission line is extrapolated to the midpoint f of the transmission line. A / B / C represent the three-phase transmission phases. In normal operation, the three phases are symmetrical, and the calculation method for phases ABC is the same. The following takes phase A as an example:

[0030]

[0031] The first voltage and the second voltage u MfA and u NfA Converted into the first phase voltage and the second phase voltage

[0032] In the above solution, determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes:

[0033] The first phasor voltage and the second phase voltage Compare and determine the comparison result amplitude U MN and angle α.

[0034]

[0035] In the formula, u MfA and u NfA They represent the voltage sampling values ​​from the M and N sides of the line to the line midpoint f, respectively. and Respectively represent u MfA and u NfA The sampling point data is converted into phasor voltage values ​​through Fourier transform.

[0036] In the above solution, determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes:

[0037] When the transmission line operates normally without internal short circuit and is synchronized, the ratio of the voltage extrapolated to the midpoint of the transmission line is approximately 1, and the angle value is approximately 0 as a judgment basis.

[0038] In the above solution, determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes:

[0039] When the ratio of the voltage calculated to the midpoint of the transmission line exceeds a first preset range, it is determined that a fault has occurred in the transmission line and no synchronous detection is performed;

[0040] When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range, and the voltage angle difference is within the second preset range, the transmission line completes the synchronization check;

[0041] When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range, and the voltage angle difference is not within the second preset range, the transmission line fails to complete the synchronization check, and the output alarm is locked.

[0042] The present application also proposes a synchronous verification system for a power transmission line, the system comprising: a voltage and current acquisition unit, a fixed value comparison unit, a midpoint voltage acquisition unit and a judgment unit;

[0043] The voltage and current acquisition unit is used to determine the protection differential current i according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0044] The fixed value comparison unit is used to compare the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0045] A midpoint voltage acquisition unit, used to, if synchronization verification is performed, respectively calculate the voltages on both sides of the transmission line to the same point of the transmission line to obtain a first voltage and a second voltage;

[0046] A judgment unit is used to determine whether the synchronization check is completed according to the ratio of the first voltage and the second voltage and the angle difference.

[0047] The present application also proposes a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0048] According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0049] According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0050] If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage;

[0051] Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

[0052] The present application also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to perform the following steps:

[0053] According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0054] According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0055] If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage;

[0056] Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

[0057] The embodiment of the present invention has the following beneficial effects: first, according to the voltage and current on both sides of the transmission line, the corresponding protection differential current i is determined. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C According to the protection differential flow i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant determines whether to perform synchronization verification; if synchronization verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage; and whether the synchronization verification is completed is determined based on the ratio and angle difference of the first voltage and the second voltage. This method combines the voltage and current information on both sides of the transmission line, comprehensively considers the voltage ratio and angle difference, and can significantly improve the accuracy, reliability and real-time performance of the transmission line synchronization verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] 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 or the description of the prior art 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.

[0059] in:

[0060] Figure 1 A schematic flow chart of a synchronous verification method for a power transmission line in one embodiment;

[0061] Figure 2 Schematic diagram of parameter distribution of MN double-terminal transmission line in one embodiment;

[0062] Figure 3 This is a schematic diagram of the accurate model of the Berylon equivalent circuit;

[0063] Figure 4 Schematic diagram of the transmission line synchronization verification module. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0065] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention; however, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details; in other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described, and it should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments presented here; on the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art.

[0066] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "a", "an" and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise, and it should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0067] To facilitate understanding, the relevant terms involved in this application are first introduced below.

[0068] (1) The wave equation is a set of differential equations derived from Maxwell's equations that describe the characteristics of electromagnetic field fluctuations. It is an important partial differential equation and the most accurate electrical model for describing the characteristics of transmission line faults.

[0069] (2) Berelon et al. connected the distributed parameter elements in series with the lumped parameter elements and the lossless transmission line, and used the more general lumped parameter and lossless transmission line fluctuation process to numerically solve the electrical characteristics of the line.

[0070] In the prior art, the ping-pong synchronization method mainly utilizes the characteristics of the stable communication delay and fixed communication path of the network, and realizes synchronization by sending network probe messages. Specifically, this side sends a frame of message and records the sending time T1. The protection device on the opposite side replies after receiving the message, and this side records the time T2 when the reply message is received; by calculating the time difference (T2-T1) between sending and receiving messages, the communication delay ΔT of the protection devices on both sides can be calculated, and used for data synchronization. However, the premise of this method is that the communication sending and receiving routes of the protection devices on both sides must be consistent; in actual applications, if the communication equipment selects different routes, or the communication network is blocked due to sudden traffic and other reasons, resulting in a large error in the data calculated by a ping-pong synchronization, it will directly lead to a large error in the aligned sampling data, and then there is a risk of protection misoperation.

[0071] Current differential protection is the main protection of high-voltage transmission line relay protection, and it is also the most important and basic protection method of high-voltage transmission line relay protection. This application proposes a synchronization verification method based on transmission lines. This method comprehensively considers the distributed parameters and electrical quantity information of the transmission lines, and uses the wave equation and the Beryl equivalent circuit model to realize real-time verification of the data synchronization accuracy on both sides of the transmission line, providing a new solution for improving the reliability of current differential protection. Through this method, an alarm lockout message can be output when the differential synchronization accuracy is poor, avoiding the false operation of the current differential protection and ensuring the safe and stable operation of the power grid.

[0072] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention; optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0073] like Figure 1 As shown, in one embodiment, a synchronization verification method for a power transmission line is provided, and the synchronization verification method for a power transmission line includes steps S101 to S104, which are described in detail as follows:

[0074] S101. Determine the protection differential current i according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0075] like Figure 2 As shown, taking the MN line as an example, the protection differential current i is determined according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C , specifically including:

[0076] Collect the voltage u on both sides of the transmission line mA / u mB / u mC 、u nA / u nB / u nC and current i mA / i mB / i mC 、i nA / i nB / i nC ,

[0077] Determine the protection differential current i according to the voltage and current on both sides of the transmission line diffA / B / C :

[0078] i diffA / B / C=|i mA / B / C +i nA / B / C |

[0079] Determine the sudden change Δi of the current on both sides of the transmission line according to the voltage and current on both sides of the transmission line mA / B / C , Δi nA / B / C :

[0080] Δi mA / B / C =|i mA / B / C.t1 -i mA / B / C.t0 |

[0081] Δi nA / B / C =|i nA / B / C.t1 -i nA / B / C.t0 |

[0082] Wherein, t1 represents the current electrical quantity information, and t0 represents the electrical quantity information at the moment when t1 minus the preset time is subtracted.

[0083] Specifically, the line distribution parameter setting value of the transmission line protection device is obtained, and the protection differential current i of the transmission line is calculated. diffA / B / C and the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C A / B / C represent the three-phase transmission phases. In normal operation, the three phases are symmetrical, and the calculation method for phases A, B and C is the same. The following takes phase A as an example:

[0084] i diffA =|i mA +i nA |(1)

[0085] Δi mA =|i mA.t1- i mA.t0 |(2)

[0086] Δi nA =|i nA.t1- i nA.t0 |(3)

[0087] In the formula, t1 represents the current electrical quantity information, and t0 represents the electrical quantity information at the moment t1 minus 20ms.

[0088] S102, according to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0089] In some embodiments, according to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C, Δi nA / B / C The comparison relationship with the sudden current starting value determines whether to perform synchronization verification, including:

[0090] Preset differential current action setting value I on both sides of the transmission line set And the sudden current starting value I qd ;

[0091] If i diffA / B / C >I set or Δi mA / B / C >I qd or Δi nA / B / C >I qd , then no synchronization check is performed;

[0092] If i diffA / B / C <I set And Δi mA / B / C <I qd , Δi nA / B / C <I qd , then perform synchronization verification.

[0093] Take phase A as an example: the differential current action setting I of the protection devices on both sides of the transmission line set And the sudden current starting value I qd For comparison, if I diffA >I set or ΔI mA >I qd or ΔI nA >I qd , it means that the protection device is in the protection start state and no synchronization check is performed; if I diffA <I set And ΔI mA <I qd , ΔI nA <I qd , then continue with the synchronization verification calculation.

[0094] According to the solution formula of the wave equation, the voltage and current at a certain point in the transmission line can be detected, and the distributed parameters of the transmission line are determined, and the voltage and current at any point in the transmission line can be calculated.

[0095] The two-terminal transmission line model is replaced by the Berylon equivalent model. The model takes into account the influence of transmission delay and distributed capacitance. The inductance and capacitance per unit length of the line are assumed to be L0 and C0 respectively. The positive direction of voltage and current is Figure 3 The corresponding equivalent circuit is as follows Figure 4 As shown, when dx→0, it is the accurate model of the line, so when the line MN is fully connected:

[0096] S103: If a synchronous check is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain a first voltage and a second voltage;

[0097] In some embodiments, if synchronization verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage, which specifically includes:

[0098] The default transmission line is MN, and its inductance and capacitance per unit length are L0 and C0 respectively:

[0099]

[0100] In the formula, τ = l / v represents the transmission time of electromagnetic waves along the entire length of the line. It represents wave impedance;

[0101] Using the voltage and current measurements at the N terminal, the voltage and current at the M terminal are calculated;

[0102] Using the voltage and current measurements at the M terminal, the voltage and current at the N terminal are calculated;

[0103] The voltage collected at the M and N sides of the transmission line is extrapolated to the midpoint f of the transmission line:

[0104]

[0105] The first voltage and the second voltage u MfA and u NfA Converted into the first phase voltage and the second phase voltage

[0106] Preferably, based on formula (4), u at the M end is M (t), i M (t) is considered as an unknown variable, and u at different times of the N terminal is N 、i N Assuming that the measured signal can be obtained, then by solving equation (4) simultaneously, we can achieve: using the N-terminal electrical quantity to describe the M-terminal electrical quantity. The solution is:

[0107]

[0108] Formula (5) can be called the analytical expression of the basic solution of the line (also called the single-ended solution), the right side of the equation is the electrical quantity of the N end, and τ = l / v is known.

[0109] Similarly, we can also get: use the electrical quantity at the M end to find the electrical quantity at the N end. The solution is:

[0110]

[0111] In equations (5) and (6), the current direction is set to flow from the M terminal to the N terminal, as Figure 2 shown.

[0112] In order to convert it into the obtained measurement signal, the time variable of equation (5) is subtracted by τ, and we have:

[0113]

[0114] Similarly, the time variables on the left side of equation (7) are adjusted to t, and the time variables on the right side are adjusted accordingly. Then, the basic solution of the electrical quantity at the N end of the lossless conductor can be deduced and converted into the obtained measurement signal, which is:

[0115]

[0116] Formulas (7) and (8) show that: Figure 2 When the circuit MN shown is completely connected and has no internal short circuit, the voltage and current at the M terminal can be calculated using the voltage and current measurement values ​​at the N terminal; similarly, the voltage and current at the N terminal can be calculated using the voltage and current measurement values ​​at the M terminal.

[0117] According to equations (7) and (8), the voltage collected at the M and N sides of the transmission line is extrapolated to the midpoint f of the transmission line.

[0118]

[0119] S104: Determine whether the synchronization check is completed according to the ratio of the first voltage to the second voltage and the angle difference.

[0120] In some embodiments, determining whether the synchronization check is completed according to the ratio of the first voltage to the second voltage and the angle difference specifically includes:

[0121] The first phase voltage and the second phase voltage Compare and determine the comparison result amplitude U MN and angle α.

[0122]

[0123] In the formula, u MfA and u NfA They represent the voltage sampling values ​​from the M and N sides of the line to the line midpoint f, respectively. and Respectively represent u MfA and u NfA The sampling point data is converted into phasor voltage values ​​through Fourier transform.

[0124] Since the voltage u MfA and uNfA These are all sampling point data, which need to be converted into phasor voltage through Fourier transform. and Then compare the phasor voltage values ​​obtained by extrapolating the two sides of the transmission line to the midpoint f, and output the comparison result amplitude U MN and angle α.

[0125] In some embodiments, determining whether the synchronization check is completed according to the ratio of the first voltage to the second voltage and the angle difference specifically includes:

[0126] When the transmission line operates normally without internal short circuit and is synchronized, the ratio of the voltage extrapolated to the midpoint of the transmission line is approximately 1, and the angle value is approximately 0 as a judgment basis.

[0127] Specifically, the accuracy of synchronization between the two sides of the transmission line is judged by the ratio and angle difference of the voltages on both sides of the transmission line, and different synchronization detection results are output according to different voltage ratios and angle differences, so as to ensure the reliability of current differential protection in the transmission line in real time.

[0128] In some embodiments, determining whether the synchronization check is completed according to the ratio of the first voltage to the second voltage and the angle difference specifically includes:

[0129] When the ratio of the voltage calculated to the midpoint of the transmission line exceeds a first preset range, it is determined that a fault has occurred in the transmission line and no synchronous detection is performed;

[0130] When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range, and the voltage angle difference is within the second preset range, the transmission line completes the synchronization check;

[0131] When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range and the voltage angle difference is not within the second preset range, the transmission line has not completed the synchronization check and the output alarm is locked.

[0132] Specifically, when the transmission line is operating normally without internal short circuit and is synchronized, U MN The ratio of should be approximately 1, and the angle value of α should be approximately 0; when U MN When the ratio exceeds 0.92 to 1.08, the transmission line may fail and no synchronization detection is performed. MN When the ratio is within the range of 0.92 to 1.08, if -10<α<10, it means that the synchronization accuracy on both sides of the transmission line is good. Otherwise, it means that the synchronization accuracy on both sides of the transmission line is poor, and an alarm blocking message is output.

[0133] In summary, the present invention comprehensively considers the influence of the distributed parameters of the transmission line, makes full use of the electrical quantity information of the transmission line, and determines the accuracy of synchronization timing by inferring the phase difference of the line midpoint voltage from both sides of the line through the Berylon model and the wave equation. The transmission line parameters are known, and only the voltage and current electrical information collected by the line protection device can be used to realize the real-time verification of the correctness of the line differential protection ping-pong synchronization timing, without adding any hardware equipment, which will greatly improve the accuracy and correctness of the transmission line synchronization verification, can timely detect synchronization anomalies and communication route inconsistencies, and further improve the reliability of line differential protection.

[0134] The present application also proposes a synchronous verification system for a power transmission line, the system comprising: a voltage and current acquisition unit, a fixed value comparison unit, a midpoint voltage acquisition unit and a judgment unit;

[0135] The voltage and current acquisition unit is used to determine the protection differential current i according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0136] The fixed value comparison unit is used to compare the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0137] A midpoint voltage acquisition unit, used to, if synchronization verification is performed, respectively calculate the voltages on both sides of the transmission line to the same point of the transmission line to obtain a first voltage and a second voltage;

[0138] A judgment unit is used to determine whether the synchronization check is completed according to the ratio of the first voltage and the second voltage and the angle difference.

[0139] The present application also proposes a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0140] According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0141] According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0142] If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage;

[0143] Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

[0144] The present application also proposes a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to perform the following steps:

[0145] According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ;

[0146] According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification;

[0147] If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage;

[0148] Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

[0149] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0150] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present application. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. The above disclosure is only a preferred embodiment of the present invention, and of course it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A synchronization verification method for a power transmission line, characterized in that: The method comprises: According to the voltage and current on both sides of the transmission line, determine its protection differential current i diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ; According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification; If synchronous verification is performed, the voltages on both sides of the transmission line are respectively extrapolated to the same point of the transmission line to obtain the first voltage and the second voltage; Whether the synchronization check is completed is determined according to the ratio of the first voltage to the second voltage and the angle difference.

2. The synchronous verification method for a power transmission line according to claim 1, characterized in that: The protection differential current i is determined according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C , specifically including: Collect the voltage u on both sides of the transmission line mA / u mB / u mC 、u nA / u nB / u nC and current i mA / i mB / i mC 、i nA / i nB / i nC , Determine the protection differential current i according to the voltage and current on both sides of the transmission line diffA / B / C : i diffA / B / C =|i mA / B / C +i nA / B / C | Determine the sudden change Δi of the current on both sides of the transmission line according to the voltage and current on both sides of the transmission line mA / B / C , Δi nA / B / C : Δi mA / B / C =|i mA / B / C.t1 -i mA / B / C.t0 | Δi nA / B / C =|i nA / B / C.t1 -i nA / B / C.t0 | Wherein, t1 represents the current electrical quantity information, and t0 represents the electrical quantity information at the moment when t1 minus the preset time is subtracted.

3. The synchronous verification method for a power transmission line according to claim 2, characterized in that: According to the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting value determines whether to perform synchronization verification, which specifically includes: Preset the differential current action setting value I on both sides of the transmission line set And the sudden current starting value I qd ; If i diffA / B / C >I set or Δi mA / B / C >I qd or Δi nA / B / C >I qd , then no synchronization check is performed; If i diffA / B / C <I set And Δi mA / B / C <I qd , Δi nA / B / C <I qd , then perform synchronization verification.

4. The synchronous verification method for a power transmission line according to claim 3, characterized in that: If the synchronization check is performed, the voltages on both sides of the transmission line are respectively calculated to the same point of the transmission line to obtain the first voltage and the second voltage, which specifically includes: The default transmission line is MN, and its inductance and capacitance per unit length are L0 and C0 respectively: In the formula, τ = l / v represents the transmission time of electromagnetic waves along the entire length of the line. It represents wave impedance; Using the voltage and current measurements at the N terminal, the voltage and current at the M terminal are calculated; Using the voltage and current measurements at the M terminal, the voltage and current at the N terminal are calculated; The voltage collected at the M and N sides of the transmission line is extrapolated to the midpoint f of the transmission line. A / B / C represent the three-phase transmission phases. In normal operation, the three phases are symmetrical, and the calculation method for phases ABC is the same. The following takes phase A as an example: The first voltage and the second voltage u MfA and u NfA Converted into the first phase voltage and the second phase voltage 5. The synchronous verification method for a power transmission line according to claim 4, characterized in that: The determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes: The first phasor voltage and the second phase voltage Compare and determine the comparison result amplitude U MN and angle α. Where: u MfA and u NfA They represent the voltage sampling values ​​from the M and N sides of the line to the line midpoint f, respectively. and Respectively represent u MfA and u NfA The sampling point data is converted into phasor voltage values ​​through Fourier transform.

6. The synchronous verification method for a power transmission line according to claim 5, characterized in that: The determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes: When the transmission line operates normally without internal short circuit and is synchronized, the ratio of the voltage extrapolated to the midpoint of the transmission line is approximately 1, and the angle value is approximately 0 as a judgment basis.

7. The synchronization verification method for a power transmission line according to claim 6, characterized in that: The determining whether the synchronization check is completed according to the ratio and the angle difference between the first voltage and the second voltage specifically includes: When the ratio of the voltage calculated to the midpoint of the transmission line exceeds a first preset range, it is determined that a fault has occurred in the transmission line and no synchronous detection is performed; When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range, and the voltage angle difference is within the second preset range, the transmission line completes the synchronization check; When the ratio of the voltages calculated to the midpoint of the transmission line is within the first preset range, and the voltage angle difference is not within the second preset range, the transmission line has not completed the synchronization check, and the output alarm is locked.

8. A synchronous verification system for a power transmission line, characterized in that: The system comprises: a voltage and current acquisition unit, a fixed value comparison unit, a midpoint voltage acquisition unit and a judgment unit; The voltage and current acquisition unit is used to determine the protection differential current i according to the voltage and current on both sides of the transmission line. diffA / B / C , the sudden change of current on both sides Δi mA / B / C , Δi nA / B / C ; The fixed value comparison unit is used to compare the protection differential current i diffA / B / C The differential current action constant of the transmission line and the sudden change of the current on both sides Δi mA / B / C , Δi nA / B / C The comparison relationship with the sudden change current starting constant value determines whether to perform synchronization verification; The midpoint voltage acquisition unit is used to calculate the voltages on both sides of the transmission line to the same point of the transmission line to obtain the first voltage and the second voltage if synchronization verification is performed; The judgment unit is used to determine whether the synchronization check is completed according to the ratio of the first voltage to the second voltage and the angle difference.

9. A readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 7.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method according to any one of claims 1 to 7.

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