Power distribution network line multi-terminal longitudinal over-current protection method and device

Abstract

The invention discloses a multi-terminal longitudinal overcurrent protection method and device for a power distribution network line. The method comprises the following steps: a power distribution terminal configured for each switch of a power distribution network line collects line voltage and current and switch positions; respective longitudinal mark signals are obtained according to the collected information; in response to displacement of any one longitudinal mark signal state of the switch power distribution terminal, sending a longitudinal mark signal state related to an adjacent line to the adjacent line; the power distribution terminal configured for each switch of the power distribution network line receives a longitudinal mark signal state sent by the switch power distribution terminal of the adjacent line; and the power distribution terminal configured by each switch of the power distribution network line carries out longitudinal over-current protection calculation according to the longitudinal mark signal of the power distribution terminal and the received longitudinal mark signal of the power distribution terminal of the switch of the adjacent line. According to the scheme, fault section judgment and rapid and accurate fault isolation of a complex power distribution network line can be achieved, the requirement for communication bandwidth is low, and the override action of longitudinal overcurrent protection when communication delay is unstable can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power system protection, and in particular to a method and device for multi-terminal longitudinal overcurrent protection of distribution network lines. Background Art

[0002] As the core link of the terminal power system, the distribution network is directly connected to the users, which is of vital importance to ensure power supply and meet user needs. The distribution network protection is responsible for removing the distribution network faults and ensuring the safety of distribution network equipment and power supply reliability. It is of great significance to design high performance for it.

[0003] However, due to its low selectivity, the traditional single-ended quantity-based distribution network line overcurrent protection generally implements hierarchical protection through the differential coordination of overcurrent protection between the upstream and downstream lines of the distribution network. However, the distribution network lines are long, and the number of line switches is mostly above 4. In addition, due to the long opening time of the distribution network switches, generally only two-level hierarchical protection of "substation feeder line protection + boundary line protection" or three-level hierarchical protection of "substation feeder line protection + branch line protection + boundary line protection" can be achieved. It is difficult to achieve reasonable differential coordination of the key path switches of the entire distribution network. A fault in the trunk line where the section switch is located will cause the substation feeder line overcurrent protection to be activated, which will cause a power outage on the entire line.

[0004] Moreover, the traditional overcurrent protection tripping can only realize the opening of the upstream switch of the fault point. If the power supply of the non-fault section is to be restored, the downstream switch of the fault point can only be manually opened to isolate the fault, and then the contact switch can be closed to restore the power supply. The power restoration time of the non-fault section is relatively long, which greatly affects the power supply reliability. Therefore, it is necessary to introduce highly selective longitudinal protection in the distribution network to realize accurate judgment of the fault section and precise and rapid isolation of the fault, so as to provide a basis for rapid power restoration of the non-fault section, thereby improving the power supply reliability.

[0005] In the existing distribution network protection field, there are studies on longitudinal differential protection methods based on the current differential principle. However, due to the complex structure of the distribution network, for some areas, it is necessary to implement longitudinal differential protection with 3 to 10 terminals or more. The high sampling rate of real-time analog data required for differential transmission will result in a huge amount of data transmission, which places high performance requirements on the communication channel. This obviously does not meet the requirements of economic efficiency for distribution network construction. In the existing distribution network protection field, there are also studies on longitudinal protection methods based on switch quantity transmission, but most of them are based on switch quantity signals at both ends, which are not suitable for application scenarios with complex multi-terminal line structures of distribution networks. In addition, the existing research on longitudinal protection of distribution networks does not consider the specific processing methods and interaction rules of switch quantity signals, and does not consider the situation that the unstable communication delay of the distribution network may lead to misjudgment of the fault section and over-tripping. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-terminal longitudinal overcurrent protection method and device for distribution network lines, so as to solve the problems in the prior art of difficult level difference coordination, large data transmission volume, difficult application scenarios of complex line structures, and unstable communication delay and over-level tripping.

[0007] In order to achieve the above objectives, the technical solution of this application is:

[0008] According to the first aspect of the present application, a multi-terminal longitudinal overcurrent protection method for distribution network lines is proposed, which is characterized by comprising:

[0009] Step 100: The distribution terminal configured for each switch of the distribution network line collects the line voltage and current, as well as the switch position;

[0010] Step 200: Obtain respective pilot connection flag signals according to the collected voltage and current and switch position of the power distribution terminal; the pilot connection flag signal includes: a delay permission flag and an overcurrent flag; or, the pilot connection flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag; or, the pilot connection flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag;

[0011] The overcurrent positive direction mark includes a left overcurrent positive direction mark or a right overcurrent positive direction mark, or includes both a left overcurrent positive direction mark and a right overcurrent positive direction mark; the overcurrent reverse direction mark includes a left overcurrent reverse direction mark or a right overcurrent reverse direction mark, or includes both a left overcurrent reverse direction mark and a right overcurrent reverse direction mark;

[0012] Step 300: in response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, sending the pilot connection mark signal state related to the adjacent line to the adjacent line;

[0013] Step 400: the distribution terminal configured for each switch of the distribution network line receives the state of the longitudinal connection mark signal sent by the distribution terminal of the adjacent line switch;

[0014] Step 500: The distribution terminal configured for each switch of the distribution network line calculates the longitudinal overcurrent protection according to its own longitudinal marking signal and the received longitudinal marking signal of the distribution terminal of the adjacent line switch.

[0015] According to some embodiments, the delay permission flag is recorded as OK, and the phase voltage collected at the power distribution terminal is low voltage, that is, any phase voltage is lower than the phase voltage reduction judgment value U set1 , or the line voltage is low voltage, that is, any line voltage is lower than the line voltage reduction judgment value U set2 , or when the switch is detected to be in a jump position, the delay time T of the permission flag setting is passedok Set the delay permission flag to 1, otherwise set it to 0;

[0016] The overcurrent flag, denoted as OP, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment setting value I of the distribution terminal set and otherwise set to 0;

[0017] The left overcurrent positive direction flag, denoted as LD, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment setting value I of the distribution terminal set and the fault direction is determined to be a positive direction fault to the left through voltage and current, and otherwise set to 0;

[0018] The right overcurrent positive direction flag, denoted as RD, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment setting value I of the distribution terminal set and the fault direction is determined to be a positive direction fault to the right through voltage and current, and otherwise set to 0;

[0019] The left overcurrent reverse direction flag, denoted as LN, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment setting value I of the distribution terminal set and the fault direction is determined to be a reverse direction fault to the left through voltage and current, and otherwise set to 0;

[0020] The right overcurrent reverse direction flag, denoted as RN, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment setting value I of the distribution terminal set and the fault direction is determined to be a reverse direction fault to the right through voltage and current, and otherwise set to 0.

[0021] According to some embodiments, in response to any change in the state of the pilot flag signal of the distribution terminal of this switch, the pilot flag signal state related to the adjacent line is sent to the adjacent line, specifically including:

[0022] When the pilot flag signal includes a delay permission flag and an overcurrent flag;

[0023] When any one of the overcurrent flag and the delay permission flag signal state of the distribution terminal of this switch changes, the overcurrent flag and the delay permission flag are sent to the distribution terminals of all adjacent line switches on its left and / or right.

[0024] According to some embodiments, in response to the change in the state of any pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0025] When the pilot flag signal includes: a delay permission flag, an overcurrent forward direction flag, and an overcurrent reverse direction flag, the overcurrent forward direction flag includes a left-side overcurrent forward direction flag, and the overcurrent reverse direction flag includes a left-side overcurrent reverse direction flag;

[0026] When any signal among the overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag signal state of this switch distribution terminal changes, send the left-side overcurrent forward direction flag, left-side overcurrent reverse direction flag, and delay permission flag to all switch distribution terminals of the adjacent lines on its left.

[0027] According to some embodiments, in response to the change in the state of any pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0028] When the pilot flag signal includes: a delay permission flag, an overcurrent forward direction flag, and an overcurrent reverse direction flag, the overcurrent forward direction flag includes a right-side overcurrent forward direction flag, and the overcurrent reverse direction flag includes a right-side overcurrent reverse direction flag;

[0029] When any signal among the overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag signal state of this switch distribution terminal changes, send the right-side overcurrent forward direction flag, right-side overcurrent reverse direction flag, and delay permission flag to all switch distribution terminals of the adjacent lines on its right.

[0030] According to some embodiments, in response to the change in the state of any pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0031] When the pilot flag signal includes: a delay permission flag, an overcurrent forward direction flag, and an overcurrent reverse direction flag, the overcurrent forward direction flag includes a left-side overcurrent forward direction flag and a right-side overcurrent forward direction flag, and the overcurrent reverse direction flag includes a left-side overcurrent reverse direction flag and a right-side overcurrent reverse direction flag;

[0032] When any signal among the overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag signal state of this switch distribution terminal changes, send the left-side overcurrent forward direction flag, left-side overcurrent reverse direction flag, and delay permission flag to all switch distribution terminals of the adjacent lines on its left, and send the overcurrent flag, right-side overcurrent forward direction flag, right-side overcurrent reverse direction flag, and delay permission flag to all switch distribution terminals of the adjacent lines on its right.

[0033] According to some embodiments, in response to any change in the state of the pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0034] When the pilot flag signal includes: a delay permission flag, an overcurrent flag, a forward overcurrent flag, and a reverse overcurrent flag, and the forward overcurrent flag includes a left-side forward overcurrent flag, and the reverse overcurrent flag includes a left-side reverse overcurrent flag;

[0035] When any signal among the overcurrent flag, the forward overcurrent flag, the reverse overcurrent flag, and the delay permission flag signal state of this switch distribution terminal changes, send the overcurrent flag, the left-side forward overcurrent flag, the left-side reverse overcurrent flag, and the delay permission flag to all switch distribution terminals of the adjacent lines on its left.

[0036] According to some embodiments, in response to any change in the state of the pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0037] When the pilot flag signal includes: a delay permission flag, an overcurrent flag, a forward overcurrent flag, and a reverse overcurrent flag, and the forward overcurrent flag includes a right-side forward overcurrent flag, and the reverse overcurrent flag includes a right-side reverse overcurrent flag;

[0038] When any signal among the overcurrent flag, the forward overcurrent flag, the reverse overcurrent flag, and the delay permission flag signal state of this switch distribution terminal changes, send the overcurrent flag, the right-side forward overcurrent flag, the right-side reverse overcurrent flag, and the delay permission flag to all switch distribution terminals of the adjacent lines on its right.

[0039] According to some embodiments, in response to any change in the state of the pilot flag signal of this switch distribution terminal, sending the pilot flag signal state related to the adjacent line to the adjacent line specifically includes:

[0040] When the pilot flag signal includes: a delay permission flag, an overcurrent flag, a forward overcurrent flag, and a reverse overcurrent flag, the forward overcurrent flag includes a left-side forward overcurrent flag and a right-side forward overcurrent flag, and the reverse overcurrent flag includes a left-side reverse overcurrent flag and a right-side reverse overcurrent flag;

[0041] When any of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag, and delay permission flag signal status of this switch distribution terminal changes, it sends the overcurrent flag, overcurrent positive direction flag to the left, overcurrent reverse direction flag to the left, and delay permission flag to all the switch distribution terminals of the adjacent lines on its left, and sends the overcurrent flag, overcurrent positive direction flag to the right, overcurrent reverse direction flag to the right, and delay permission flag to all the switch distribution terminals of the adjacent lines on its right.

[0042] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, specifically including:

[0043] Calculate the total signal of various flags according to their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches;

[0044] Determine whether the pilot overcurrent protection operates according to the total signal of the various flags.

[0045] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, specifically including:

[0046] Step 511: Calculate the total signal of various flags according to their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0047] Calculate the sum of the overcurrent flag of this switch distribution terminal and the overcurrent flags of all the left adjacent line switches received, to obtain the total left overcurrent flag signal LF;

[0048] Calculate the sum of the delay permission flags of all the left adjacent line switches received by this switch distribution terminal, to obtain the total left delay permission flag signal LOK;

[0049] Step 512: Determine whether "LF = 1, LOK = the sum of the number of left adjacent switches, and this state lasts for a duration and this state lasts for a duration greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal to the left operates, and this switch trips.

[0050] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, specifically including:

[0051] Step 521: Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0052] Calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the distribution terminals of the adjacent line switches on the right side received, to obtain the total right-side overcurrent flag signal RF;

[0053] Calculate the sum of the delay permission flags of all the distribution terminals of the adjacent line switches on the right side received by this switch distribution terminal, to obtain the total right-side delay permission flag signal ROK;

[0054] Step 522: Determine whether "RF = 1, ROK = the sum of the numbers of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal for the right side acts, and this switch trips.

[0055] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, specifically including:

[0056] Step 531: Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0057] Calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the distribution terminals of the adjacent line switches on the left side received, to obtain the total left-side overcurrent flag signal LF; calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the distribution terminals of the adjacent line switches on the right side received, to obtain the total right-side overcurrent flag signal RF;

[0058] Calculate the sum of the delay permission flags of all the distribution terminals of the adjacent line switches on the left side received by this switch distribution terminal, to obtain the total left-side delay permission flag signal LOK; calculate the sum of the delay permission flags of all the distribution terminals of the adjacent line switches on the right side received by this switch distribution terminal, to obtain the total right-side delay permission flag signal ROK;

[0059] Step 532: Determine whether "LF = 1, LOK = the sum of the numbers of adjacent switches on the left side, and the duration of this state and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal for the left side acts, and this switch trips; if it does not hold, further determine whether "RF = 1, ROK = the sum of the numbers of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co"If it holds, it is determined that the switch distribution terminal on the right side has a pilot overcurrent protection action and trips this switch.

[0060] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches. Specifically, it includes:

[0061] Step 541: According to its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, calculate the total signal of various flags, including:

[0062] Calculate the sum of the overcurrent positive direction flags of this switch distribution terminal for the left side and the overcurrent positive direction flags sent by all the distribution terminals of adjacent left-side line switches received, to obtain the total signal of the overcurrent positive direction flag LDF for this switch on the left side;

[0063] Calculate the sum of the overcurrent reverse direction flags of this switch distribution terminal for the left side and the overcurrent reverse direction flags sent by all the distribution terminals of adjacent left-side line switches received, to obtain the total signal of the overcurrent reverse direction flag LNF for this switch on the left side;

[0064] Calculate the sum of the delay permission flags of all the distribution terminals of adjacent left-side line switches received by this switch distribution terminal, to obtain the total signal of the left-side delay permission flag LOK;

[0065] Step 542: Determine whether "LDF≥1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that the switch distribution terminal on the left side has a pilot overcurrent protection action and trips this switch.

[0066] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches. Specifically, it includes:

[0067] Step 551: According to its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, calculate the total signal of various flags, including:

[0068] Calculate the sum of the overcurrent positive direction flags of this switch distribution terminal for the right side and the overcurrent positive direction flags of all the distribution terminals of adjacent right-side line switches received, to obtain the total signal of the overcurrent direction flag RDF for this switch on the right side;

[0069] Calculate the sum of the overcurrent reverse direction flag of this switch distribution terminal and the overcurrent reverse direction flags sent by all the switch distribution terminals of the adjacent lines on the right side received, and obtain the total RNF of the overcurrent reverse direction flag signal of this switch for the right side;

[0070] Calculate the sum of the delay permission flags of all the switch distribution terminals of the adjacent lines on the right side received by this switch distribution terminal, and obtain the total ROK of the delay permission flag signal on the right side;

[0071] Step 552: Determine whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right side, and this state lasts for a time longer than the communication confirmation time T" co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal for the right side acts, and this switch trips.

[0072] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals of the adjacent line switch distribution terminals received, specifically including:

[0073] Step 561: Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals of the adjacent line switch distribution terminals received, including:

[0074] Calculate the sum of the overcurrent forward direction flag of this switch distribution terminal and the overcurrent forward direction flags sent by all the switch distribution terminals of the adjacent lines on the left side received, and obtain the total LDF of the overcurrent forward direction flag signal of this switch for the left side; Calculate the sum of the overcurrent forward direction flag of this switch distribution terminal and the overcurrent forward direction flags of all the switch distribution terminals of the adjacent lines on the right side received, and obtain the total RDF of the overcurrent direction flag signal of this switch for the right side;

[0075] Calculate the sum of the overcurrent reverse direction flag of this switch distribution terminal and the overcurrent reverse direction flags sent by all the switch distribution terminals of the adjacent lines on the left side received, and obtain the total LNF of the overcurrent reverse direction flag signal of this switch for the left side; Calculate the sum of the overcurrent reverse direction flag of this switch distribution terminal and the overcurrent reverse direction flags sent by all the switch distribution terminals of the adjacent lines on the right side received, and obtain the total RNF of the overcurrent reverse direction flag signal of this switch for the right side;

[0076] Calculate the sum of the delay permission flags of all the switch distribution terminals of the adjacent lines on the left side received by this switch distribution terminal, and obtain the total LOK of the delay permission flag signal on the left side; Calculate the sum of the delay permission flags of all the switch distribution terminals of the adjacent lines on the right side received by this switch distribution terminal, and obtain the total ROK of the delay permission flag signal on the right side;

[0077] Step 562: Determine whether "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the distribution terminal of this switch has a longitudinal overcurrent protection action on the left side, and this switch trips; if it does not hold, further determine whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the distribution terminal of this switch has a longitudinal overcurrent protection action on the right side, and this switch trips. co ", if it holds, it is determined that the distribution terminal of this switch has a longitudinal overcurrent protection action on the left side, and this switch trips; if it does not hold, further determine whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the distribution terminal of this switch has a longitudinal overcurrent protection action on the right side, and this switch trips.

[0078] According to some embodiments, the distribution terminals configured for each switch on the distribution network line all perform calculations for longitudinal overcurrent protection based on their own longitudinal flag signals and the longitudinal flag signals received from the distribution terminals of adjacent line switches. Specifically, it includes:

[0079] Step 571: Calculate the total signal of various flags based on the longitudinal flag signal of itself and the longitudinal flag signals received from the distribution terminals of adjacent line switches, including:

[0080] Calculate the sum of the overcurrent flag of the distribution terminal of this switch and the overcurrent flags of all the distribution terminals of adjacent switches on the left received, to obtain the total left overcurrent flag signal LF;

[0081] Calculate the sum of the overcurrent positive direction flag of the distribution terminal of this switch for the left side and the overcurrent positive direction flags sent by all the distribution terminals of adjacent switches on the left received, to obtain the total left overcurrent positive direction flag signal LDF of this switch;

[0082] Calculate the sum of the overcurrent reverse direction flag of the distribution terminal of this switch for the left side and the overcurrent reverse direction flags sent by all the distribution terminals of adjacent switches on the left received, to obtain the total left overcurrent reverse direction flag signal LNF of this switch;

[0083] Calculate the sum of the delay permission flags of all the distribution terminals of adjacent switches on the left received by the distribution terminal of this switch, to obtain the total left delay permission flag signal LOK;

[0084] Step 572: Determine whether the distribution terminal enables the longitudinal overcurrent protection direction judgment control word, that is, determine whether the longitudinal overcurrent protection direction judgment control word is 1. If not, execute Step 563, that is, execute the longitudinal overcurrent protection logic without direction judgment. If so, execute Step 564, that is, execute the longitudinal overcurrent protection logic with direction judgment;

[0085] Step 573: Perform the longitudinal overcurrent protection logic without direction judgment. The specific steps are as follows:

[0086] Judge whether "LF = 1, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the distribution terminal of this switch has an action on the longitudinal overcurrent protection on the left, and this switch trips; co If it holds, it is determined that the distribution terminal of this switch has an action on the longitudinal overcurrent protection on the left, and this switch trips;

[0087] Step 574: Perform the longitudinal overcurrent protection logic for judging the direction, and the specific steps are as follows:

[0088] Judge whether "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T" holds. co If it holds, it is determined that the distribution terminal of this switch has an action on the longitudinal overcurrent protection on the left, and this switch trips.

[0089] According to some embodiments, the distribution terminals configured for each switch of the distribution network line perform the calculation of the longitudinal overcurrent protection according to their own longitudinal flag signals and the longitudinal flag signals received from the distribution terminals of the adjacent line switches, specifically including:

[0090] Step 581: Calculate the total signal of various flags according to its own longitudinal flag signal and the longitudinal flag signals received from the distribution terminals of the adjacent line switches on the right, including:

[0091] Calculate the sum of the overcurrent flag of the distribution terminal of this switch and the overcurrent flags of all the distribution terminals of the adjacent line switches on the right received, to obtain the total overcurrent flag signal RF for the right side;

[0092] Calculate the sum of the overcurrent positive direction flag of the distribution terminal of this switch for the right side and the overcurrent positive direction flags of all the distribution terminals of the adjacent line switches on the right received, to obtain the total overcurrent direction flag signal RDF for the right side of this switch;

[0093] Calculate the sum of the overcurrent reverse direction flag of the distribution terminal of this switch for the right side and the overcurrent reverse direction flags sent by all the distribution terminals of the adjacent line switches on the right received, to obtain the total overcurrent reverse direction flag signal RNF for the right side of this switch;

[0094] Calculate the sum of the delay permission flags of all the distribution terminals of the adjacent line switches on the right received by the distribution terminal of this switch, to obtain the total delay permission flag signal ROK for the right side;

[0095] Step 582: Judge whether the distribution terminal enables the longitudinal overcurrent protection direction judgment control word, that is, judge whether the longitudinal overcurrent protection direction judgment control word is 1. If not, execute Step 563, that is, execute the longitudinal overcurrent protection logic without direction judgment. If so, execute Step 564, that is, execute the longitudinal overcurrent protection logic with direction judgment;

[0096] Step 583: Perform the longitudinal overcurrent protection logic without direction judgment, and the specific steps are as follows:

[0097] Determine whether "RF = 1, ROK = the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the distribution terminal of this switch has a right-side pilot overcurrent protection action and trips this switch; co

[0098] Step 584: Perform the logic of pilot overcurrent protection for direction judgment, and the specific steps are as follows:

[0099] Determine whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the distribution terminal of this switch has a right-side pilot overcurrent protection action and trips this switch. co

[0100] According to some embodiments, the distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of adjacent line switches, specifically including:

[0101] Step 591: Calculate the total signal of various flags based on the pilot flag signal of itself and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0102] Calculate the sum of the overcurrent flag of the distribution terminal of this switch and the overcurrent flags of all the distribution terminals of the adjacent switches on the left received, to obtain the total left-side overcurrent flag signal LF; calculate the sum of the overcurrent flag of the distribution terminal of this switch and the overcurrent flags of all the distribution terminals of the adjacent switches on the right received, to obtain the total right-side overcurrent flag signal RF;

[0103] Calculate the sum of the overcurrent positive direction flag of the distribution terminal of this switch for the left side and the overcurrent positive direction flags sent by all the distribution terminals of the adjacent switches on the left received, to obtain the total left-side overcurrent positive direction flag signal LDF of this switch; calculate the sum of the overcurrent positive direction flag of the distribution terminal of this switch for the right side and the overcurrent positive direction flags of all the distribution terminals of the adjacent switches on the right received, to obtain the total right-side overcurrent direction flag signal RDF of this switch;

[0104] Calculate the sum of the overcurrent reverse direction flag of the distribution terminal of this switch for the left side and the overcurrent reverse direction flags sent by all the distribution terminals of the adjacent switches on the left received, to obtain the total left-side overcurrent reverse direction flag signal LNF of this switch; calculate the sum of the overcurrent reverse direction flag of the distribution terminal of this switch for the right side and the overcurrent reverse direction flags sent by all the distribution terminals of the adjacent switches on the right received, to obtain the total right-side overcurrent reverse direction flag signal RNF of this switch;

[0105] ​​Calculate the sum of the delay permission flags of all the line switch and distribution terminals adjacent to the left side received by this switch and distribution terminal to obtain the total left-side delay permission flag signal LOK; calculate the sum of the delay permission flags of all the line switch and distribution terminals adjacent to the right side received by this switch and distribution terminal to obtain the total right-side delay permission flag signal ROK.

[0106] Step 592: Determine whether the pilot overcurrent protection direction judgment control word of the distribution terminal is input, that is, determine whether the pilot overcurrent protection direction judgment control word is 1. If not, execute Step 563, that is, execute the pilot overcurrent protection logic without direction judgment. If so, execute Step 564, that is, execute the pilot overcurrent protection logic with direction judgment.

[0107] Step 593: Perform the pilot overcurrent protection logic without direction judgment. The specific steps are as follows:

[0108] Judge whether "LF = 1, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the switch and distribution terminal of this switch performs a pilot overcurrent protection action on the left side and trips this switch; if it does not hold, further judge whether "RF = 1, ROK = the sum of the number of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the switch and distribution terminal of this switch performs a pilot overcurrent protection action on the right side and trips this switch.

[0109] Step 594: Perform the pilot overcurrent protection logic with direction judgment. The specific steps are as follows:

[0110] Judge whether "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the switch and distribution terminal of this switch performs a pilot overcurrent protection action on the left side and trips this switch; if it does not hold, further judge whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the switch and distribution terminal of this switch performs a pilot overcurrent protection action on the right side and trips this switch.

[0111] According to some embodiments, the overcurrent element judgment setting value I set is greater than the maximum load current of the distribution network line.

[0112] According to some embodiments, the phase voltage reduction judgment setting value U set1 has a value range of 0 < U set1 < U h1 , where U h1 is the rated value of the phase voltage of the distribution network line.

[0113] According to some embodiments, the line voltage reduction judgment setting value U set2 has a value range of 0 < U set2 < U h2 , where U h2 is the rated line voltage of the distribution network line.

[0114] According to some embodiments, the allow flag setting delay T ok is set according to the principle of avoiding the generation of the phase voltage low voltage or the line voltage low voltage prior to the overcurrent flag when a short - circuit fault occurs in the distribution network line.

[0115] According to some embodiments, the communication confirmation time Tco is the design delay during the construction of the communication channels of adjacent switch distribution terminals.

[0116] According to the second aspect of the present application, a multi - terminal pilot over - current protection device for a distribution network line is proposed, including: a collection unit, a flag signal determination unit, a signal sending unit, a signal receiving unit, and a pilot over - current protection calculation unit; where:

[0117] The collection unit is used to collect the line voltage, current, and switch position through the distribution terminals configured for each switch of the distribution network line;

[0118] The flag signal determination unit is used to obtain respective pilot flag signals according to the voltage, current, and switch position collected by the distribution terminal; the pilot flag signals include: a delay allow flag and an over - current flag; or, the pilot flag signals include: a delay allow flag, an over - current positive - direction flag, and an over - current negative - direction flag; or, the pilot flag signals include: a delay allow flag, an over - current flag, an over - current positive - direction flag, and an over - current negative - direction flag;

[0119] The over - current positive - direction flag includes a left - hand over - current positive - direction flag or a right - hand over - current positive - direction flag, or both a left - hand over - current positive - direction flag and a right - hand over - current positive - direction flag; the over - current negative - direction flag includes a left - hand over - current negative - direction flag or a right - hand over - current negative - direction flag, or both a left - hand over - current negative - direction flag and a right - hand over - current negative - direction flag;

[0120] The signal sending unit is used to send the pilot flag signal state related to the adjacent line to the adjacent line in response to the change in the state of any pilot flag signal of the distribution terminal of the present switch;

[0121] The signal receiving unit receives the pilot flag signal state sent by the distribution terminal of the adjacent - line switch configured for each switch of the distribution network line;

[0122] Longitudinal overcurrent protection calculation unit: The distribution terminals configured for each switch of the distribution network line calculate the longitudinal overcurrent protection according to their own longitudinal marking signals and the longitudinal marking signals received from the distribution terminals of the adjacent line switches.

[0123] According to a second aspect of the present application, an electronic device is proposed, including a processor and a memory, wherein the memory stores a program, and the program can be loaded by the processor to execute the above-mentioned multi-terminal longitudinal overcurrent protection method for distribution network lines.

[0124] According to a second aspect of the present application, a computer-readable storage medium is proposed, storing a computer program, and when the computer program is executed by a processor, the above-mentioned multi-terminal longitudinal overcurrent protection method for distribution network lines is implemented.

[0125] The beneficial effects of the present invention are:

[0126] 1. High selectivity, capable of locating the fault section and isolating the fault: The present invention realizes highly selective longitudinal overcurrent protection based on information exchange between adjacent line switch distribution terminals, which can realize accurate judgment of the fault section and rapid isolation of the fault, providing a basis for quickly restoring power supply to non-fault sections, thereby improving power supply reliability.

[0127] 2. Small data transmission volume and low communication bandwidth requirement: The present invention requires that adjacent line switch distribution terminals communicate and exchange longitudinal connection mark signals, with little interactive electrical quantity information, which are all switch quantity signals, and the number of bytes transmitted in communication is small, which requires low communication bandwidth.

[0128] 3. Wide application scenarios: The present invention realizes multi-terminal longitudinal overcurrent protection of distribution network lines based on information interaction between adjacent line switch distribution terminals, and can be applied to multi-terminal complex distribution network line structures.

[0129] 4. It can prevent the longitudinal overcurrent protection from skipping action when the communication delay is unstable: the present invention introduces a delay permission mark to judge the longitudinal overcurrent protection, which can avoid the longitudinal overcurrent protection skipping action accident caused by the communication transmission time of the distribution terminals on both sides of the line being greater than the communication confirmation time when a fault occurs downstream of a line in the distribution network when the communication is unstable, thereby misjudging the fault section. BRIEF DESCRIPTION OF THE DRAWINGS

[0130] Figure 1 This is a flow chart of a multi-terminal longitudinal overcurrent protection method for a distribution network line provided in the first embodiment of the present application;

[0131] Figure 2 This is a flow chart of a multi-terminal longitudinal overcurrent protection method for a distribution network line provided in the second embodiment of the present application;

[0132] Figure 3It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the third embodiment of this application;

[0133] Figure 4 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the fourth embodiment of this application;

[0134] Figure 5 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the fifth embodiment of this application;

[0135] Figure 6 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the sixth embodiment of this application;

[0136] Figure 7 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the seventh embodiment of this application;

[0137] Figure 8 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the eighth embodiment of this application;

[0138] Figure 9 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the ninth embodiment of this application;

[0139] Figure 10 It is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided in the tenth embodiment of this application;

[0140] Figure 11 It is a schematic diagram of fault distribution when the distribution network line is operating in an open loop provided in the eleventh embodiment of this application.

[0141] Figure 12 It is a schematic diagram of fault distribution when the distribution network line is operating in a closed loop provided in the eleventh embodiment of this application.

[0142] Figure 13 It is a schematic diagram of the structure of a multi-terminal pilot overcurrent protection device for a distribution network line provided in the twelfth embodiment of this application.

[0143] Figure 14 Shown is a structural diagram of an electronic device provided in this application. Detailed implementation manners

[0144] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below based on the accompanying drawings and embodiments. It should be understood that the specific implementations described herein are only used to explain the present invention and do not limit the present invention.

[0145] At present, in the distribution network, the method of hierarchical protection through the coordination of overcurrent protection grading between the upstream and downstream lines of the distribution network has difficult grading coordination and a long power restoration time for non-fault sections, which greatly affects the power supply reliability. When using pilot differential protection based on the principle of current differential, when the distribution network structure is complex, there are problems such as a large amount of data transmission, difficulty in applying to scenarios with complex line structures, and unstable communication delays leading to overstepping tripping. In view of this, the present application proposes a multi-terminal pilot overcurrent protection method for distribution network lines, establishes the processing and interaction principles of pilot flag signals for distribution terminals of distribution network lines, and realizes multi-terminal pilot overcurrent protection based on multi-terminal electrical switch quantity information of distribution network lines, which has high applicability to the distribution network, and introduces a delay permission flag to avoid overstepping actions of pilot overcurrent protection when communication delays are unstable.

[0146] Embodiment 1:

[0147] Figure 1 The figure shows a flowchart of a multi-terminal pilot overcurrent protection method for distribution network lines provided by an embodiment of the present application, including the following steps:

[0148] S100: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0149] S200: According to the voltage and current collected by the distribution terminal, as well as the switch position, obtain their respective pilot flag signals.

[0150] The pilot flag signal includes: a delay permission flag and an overcurrent flag; or, the pilot flag signal includes: a delay permission flag, an overcurrent positive direction flag, and an overcurrent negative direction flag; or, the pilot flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag, and an overcurrent negative direction flag.

[0151] The overcurrent positive direction flag includes a left-side overcurrent positive direction flag or a right-side overcurrent positive direction flag, or includes both a left-side overcurrent positive direction flag and a right-side overcurrent positive direction flag; the overcurrent negative direction flag includes a left-side overcurrent negative direction flag or a right-side overcurrent negative direction flag, or includes both a left-side overcurrent negative direction flag and a right-side overcurrent negative direction flag.

[0152] S300: In response to a change in the state of any pilot flag signal of the distribution terminal of the local switch, send the state of the pilot flag signal related to the adjacent line to the adjacent line.

[0153] S400: The distribution terminals configured for each switch of the distribution network line receive the state of the pilot flag signal sent by the distribution terminal of the adjacent line switch.

[0154] S500: The distribution terminals configured for each switch on the distribution network line perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches.

[0155] In some embodiments, S500 further includes: calculating the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of the adjacent line switches; determining whether the pilot overcurrent protection operates based on the total signal of various flags.

[0156] In some implementations, the delay permission flag, denoted as OK, is set to 1 after a delay permission flag setting delay T when the phase voltage collected by the distribution terminal is low voltage, that is, any phase voltage is lower than the phase voltage reduction judgment value U set1 , or the line voltage is low voltage, that is, any line voltage is lower than the line voltage reduction judgment value U set2 , or when it is detected that this switch is in the open position, otherwise it is set to 0; ok The overcurrent flag, denoted as OP, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment value I

[0157] of this distribution terminal, otherwise it is set to 0; set The left-side overcurrent positive direction flag, denoted as LD, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment value I

[0158] of this distribution terminal, and it is determined that the fault direction is a positive direction fault to the left through voltage and current, otherwise it is set to 0; set The right-side overcurrent positive direction flag, denoted as RD, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment value I

[0159] of this distribution terminal, and it is determined that the fault direction is a positive direction fault to the right through voltage and current, otherwise it is set to 0; set The left-side overcurrent reverse direction flag, denoted as LN, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment value I

[0160] of this distribution terminal, and it is determined that the fault direction is a reverse direction fault to the left through voltage and current, otherwise it is set to 0; set The right-side overcurrent reverse direction flag, denoted as RN, is set to 1 when the effective value of any phase current collected by the distribution terminal is greater than the overcurrent element judgment value I

[0161] of this distribution terminal, and it is determined that the fault direction is a reverse direction fault to the right through voltage and current, otherwise it is set to 0; setWhen the fault direction is determined to be the reverse direction (to the right) through voltage and current, the overcurrent reverse direction flag for the right side is set to 1; otherwise, it is set to 0.

[0162] Among them, the setting value I of the overcurrent element judgment set is greater than the maximum load current of the distribution network line.

[0163] The setting value U for judging the reduction of phase voltage set1 has a value range of 0 < U set1 < U h1 where U h1 is the rated value of the phase voltage of the distribution network line.

[0164] The setting value U for judging the reduction of line voltage set2 has a value range of 0 < U set2 < U h2 where U h2 is the rated value of the line voltage of the distribution network line.

[0165] The delay T for setting the enable flag ok is set according to the principle of avoiding the generation of low phase voltage or low line voltage before the overcurrent flag when a short - circuit fault occurs in the distribution network line.

[0166] The communication confirmation time Tco is the design delay during the construction of the communication channel between adjacent switch distribution terminals.

[0167] Embodiment 2:

[0168] Figure 2 The following shows a flowchart of a multi - terminal pilot over - current protection method for a distribution network line provided by the second embodiment of the present application, including the following steps:

[0169] S110: The distribution terminals configured for each switch of the distribution network line collect the line voltage, current, and switch position.

[0170] S210: According to the collected voltage, current, and switch position, each distribution terminal obtains its own pilot flag signal. The pilot flag signal includes: a delay enable flag OK and an over - current flag OP.

[0171] S310: When any one of the over - current flag and the delay enable flag signal status of the distribution terminal of this switch changes, the over - current flag and the delay enable flag are sent to all the distribution terminals of the adjacent line switches on its left.

[0172] S410: The distribution terminals configured for each switch of the distribution network line receive the pilot flag signal status sent by the distribution terminals of the adjacent line switches.

[0173] S510: The distribution terminals configured for each switch on the distribution network line perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the switches on adjacent lines. Specifically, it includes:

[0174] S511. Calculate the total signal of various flags based on the pilot flag signals of its own and the pilot flag signals received from the distribution terminals of the switches on adjacent lines, including:

[0175] Calculate the sum of the overcurrent flags of the distribution terminal of this switch and the overcurrent flags of all the distribution terminals of the switches on the adjacent lines on the left side received, to obtain the total left - hand overcurrent flag signal LF;

[0176] Calculate the sum of the delay - allowed flags of all the distribution terminals of the switches on the adjacent lines on the left side received by the distribution terminal of this switch, to obtain the total left - hand delay - allowed flag signal LOK;

[0177] S512: Judge whether "LF = 1, LOK = the sum of the number of adjacent switches on the left side, and this state lasts for a time greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch's distribution terminal on the left side acts, and this switch trips.

[0178] Embodiment 3:

[0179] Figure 3 The following shows a flowchart of a multi - terminal pilot overcurrent protection method for a distribution network line provided by the third embodiment of this application, including the following steps:

[0180] S120: The distribution terminals configured for each switch on the distribution network line collect the line voltage and current, as well as the switch position.

[0181] S220: According to the collected voltage and current, as well as the switch position, the distribution terminals obtain their respective pilot flag signals. The pilot flag signals include: delay - allowed flag OK and overcurrent flag OP.

[0182] S320: When any one of the overcurrent flag and the delay - allowed flag signal state of the distribution terminal of this switch changes, send the overcurrent flag and the delay - allowed flag to all the distribution terminals of the switches on the adjacent lines on the right side.

[0183] S420: The distribution terminals configured for each switch on the distribution network line receive the states of the pilot flag signals sent by the distribution terminals of the adjacent line switches.

[0184] S520: The distribution terminals configured for each switch on the distribution network line perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches. Specifically, it includes:

[0185] S521. Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0186] Calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the distribution terminals of the adjacent line switches on the right side received, to obtain the total right-side overcurrent flag signal RF;

[0187] Calculate the sum of the delay permission flags of all the distribution terminals of the adjacent line switches on the right side received by this switch distribution terminal, to obtain the total right-side delay permission flag signal ROK;

[0188] S522: Determine whether "RF = 1, ROK = the sum of the quantities of adjacent switches on the right side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, then determine that the pilot overcurrent protection of this switch distribution terminal for the right side acts, and trip this switch.

[0189] Embodiment 4:

[0190] Figure 4 The figure shows a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the fourth embodiment of the present application, including the following steps:

[0191] S130: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0192] S230: According to the voltage and current collected by the distribution terminal, as well as the switch position, obtain their respective pilot flag signals. The pilot flag signals include: delay permission flag OK and overcurrent flag OP.

[0193] S330: When any one of the signals in the overcurrent flag and the delay permission flag signal state of this switch distribution terminal changes, send the overcurrent flag and the delay permission flag to all the distribution terminals of the adjacent line switches on its left and right sides.

[0194] S430: The distribution terminals configured for each switch of the distribution network line receive the pilot flag signal states sent by the distribution terminals of the adjacent line switches.

[0195] S530: The distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches. Specifically, it includes:

[0196] S531. Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of adjacent line switches, including:

[0197] Calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the switch distribution terminals of the adjacent lines on the left side received, to obtain the total left-side overcurrent flag signal LF; calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all the switch distribution terminals of the adjacent lines on the right side received, to obtain the total right-side overcurrent flag signal RF.

[0198] Calculate the sum of the delay permission flags of all the switch distribution terminals of the adjacent lines on the left side received by this switch distribution terminal, to obtain the total left-side delay permission flag signal LOK; calculate the sum of the delay permission flags of all the switch distribution terminals of the adjacent lines on the right side received by this switch distribution terminal, to obtain the total right-side delay permission flag signal ROK.

[0199] S532: Judge whether "LF = 1, LOK = the sum of the numbers of adjacent switches on the left side, and the duration of this state and the duration of this state is greater than the communication confirmation time T" holds. If it holds, it is determined that the overcurrent protection of this switch distribution terminal for the left-side pilot protection acts, and this switch is tripped; if it does not hold, further judge whether "RF = 1, ROK = the sum of the numbers of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T" holds. co If it holds, it is determined that the overcurrent protection of this switch distribution terminal for the right-side pilot protection acts, and this switch is tripped. co

[0200] Embodiment 5:

[0201] Figure 5 The flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the fifth embodiment of this application is shown, including the following steps:

[0202] S140: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0203] S240: According to the collected voltage and current, as well as the switch position by the distribution terminal, obtain their respective pilot flag signals. The pilot flag signals include: delay permission flag OK, overcurrent positive direction flag, and overcurrent reverse direction flag. The overcurrent positive direction flag includes the left-side overcurrent positive direction flag LD. The overcurrent reverse direction flag includes the left-side overcurrent reverse direction flag LN.

[0204] S340: When any one of the overcurrent positive direction flag, overcurrent reverse direction flag, and delay permission flag signal state of this switch distribution terminal changes, send the left-side overcurrent positive direction flag, left-side overcurrent reverse direction flag, and delay permission flag to all the switch distribution terminals of the adjacent lines on its left side.

[0205] S440: The distribution terminals configured for each switch of the distribution network line receive the pilot flag signal states sent by the adjacent line switch distribution terminals.

[0206] S540: The distribution terminals configured for each switch on the distribution network line perform the calculation of pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches. Specifically, it includes:

[0207] S541. Calculate the total sum of signals of various flags based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches, including:

[0208] Calculate the sum of the overcurrent positive direction flag of this switch's distribution terminal and the overcurrent positive direction flags sent by all the distribution terminals of the adjacent line switches on the left side received, to obtain the total sum of the overcurrent positive direction flag signals LDF of this switch for the left side;

[0209] Calculate the sum of the overcurrent reverse direction flag of this switch's distribution terminal and the overcurrent reverse direction flags sent by all the distribution terminals of the adjacent line switches on the left side received, to obtain the total sum of the overcurrent reverse direction flag signals LNF of this switch for the left side;

[0210] Calculate the sum of the delay permission flags received by this switch's distribution terminal from all the distribution terminals of the adjacent line switches on the left side, to obtain the total sum of the left - side delay permission flag signals LOK;

[0211] S542: Determine whether "LDF≥1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and this state lasts for a time greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch's distribution terminal for the left side acts, and this switch trips.

[0212] Embodiment Six:

[0213] Figure 6 The following shows a flowchart of a multi - terminal pilot overcurrent protection method for a distribution network line provided by the sixth embodiment of this application, including the following steps:

[0214] S150: The distribution terminals configured for each switch on the distribution network line collect the line voltage and current, as well as the switch position.

[0215] S250: Based on the voltage and current collected by the distribution terminal, as well as the switch position, obtain their respective pilot flag signals. The pilot flag signals include: delay permission flag OK, overcurrent positive direction flag, and overcurrent reverse direction flag. The overcurrent positive direction flag includes the overcurrent positive direction flag RD for the right side, and the overcurrent reverse direction flag includes the overcurrent reverse direction flag RN for the right side.

[0216] S350: When any of the signal states of the overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag of this switch distribution terminal changes, it sends the overcurrent forward direction flag to the right, the overcurrent reverse direction flag to the right, and the delay permission flag to all adjacent line switch distribution terminals on its right.

[0217] S450: The distribution terminals configured for each switch on the distribution network line receive the pilot flag signal states sent by the adjacent line switch distribution terminals.

[0218] S550: Each distribution terminal configured for each switch on the distribution network line calculates the pilot overcurrent protection based on its own pilot flag signal and the pilot flag signals received from the adjacent line switch distribution terminals. Specifically, it includes:

[0219] S551. Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the adjacent line switch distribution terminals on the right, including:

[0220] Calculate the sum of the overcurrent forward direction flag to the right of this switch distribution terminal and the overcurrent forward direction flags of all adjacent line switch distribution terminals on the right received, to obtain the total overcurrent direction flag signal RDF to the right of this switch;

[0221] Calculate the sum of the overcurrent reverse direction flag to the right of this switch distribution terminal and the overcurrent reverse direction flags sent by all adjacent line switch distribution terminals on the right received, to obtain the total overcurrent reverse direction flag signal RNF to the right of this switch;

[0222] Calculate the sum of the delay permission flags of all adjacent line switch distribution terminals on the right received by this switch distribution terminal, to obtain the total delay permission flag signal ROK to the right;

[0223] S552. Determine whether "RDF≥1, RNF = 0, ROK = the sum of the number of adjacent switches on the right, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal to the right acts, and this switch trips.

[0224] Embodiment Seven:

[0225] Figure 7 The following shows a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the seventh embodiment of this application, including the following steps:

[0226] S160: The distribution terminals configured for each switch on the distribution network line collect the line voltage and current, as well as the switch position.

[0227] S260: Based on the collected voltage, current, and switch position of the distribution terminal, respective pilot flag signals are obtained. The pilot flag signals include: a delay permission flag OK, an overcurrent forward direction flag, and an overcurrent reverse direction flag. The overcurrent forward direction flag includes a left-side overcurrent forward direction flag LD and a right-side overcurrent forward direction flag RD, and the overcurrent reverse direction flag includes a left-side overcurrent reverse direction flag LN and a right-side overcurrent reverse direction flag RN.

[0228] S360: When any one of the overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag signal status of the distribution terminal of this switch changes, the left-side overcurrent forward direction flag, left-side overcurrent reverse direction flag, and delay permission flag are sent to all distribution terminals of the line switches adjacent to its left side, and the overcurrent flag, right-side overcurrent forward direction flag, right-side overcurrent reverse direction flag, and delay permission flag are sent to all distribution terminals of the line switches adjacent to its right side.

[0229] S460: The distribution terminals configured for each switch on the distribution network line receive the pilot flag signal status sent by the distribution terminals of the adjacent line switches.

[0230] S560: The distribution terminals configured for each switch on the distribution network line all perform calculations for pilot overcurrent protection based on their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches. Specifically, it includes:

[0231] S561. Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the distribution terminals of the adjacent line switches, including:

[0232] Calculate the sum of the left-side overcurrent forward direction flag of the distribution terminal of this switch and the overcurrent forward direction flags sent by all the left-side adjacent line switches received, to obtain the total left-side overcurrent forward direction flag signal LDF of this switch; calculate the sum of the right-side overcurrent forward direction flag of the distribution terminal of this switch and the overcurrent forward direction flags of all the right-side adjacent line switches received, to obtain the total right-side overcurrent direction flag signal RDF of this switch;

[0233] Calculate the sum of the left-side overcurrent reverse direction flag of the distribution terminal of this switch and the overcurrent reverse direction flags sent by all the left-side adjacent line switches received, to obtain the total left-side overcurrent reverse direction flag signal LNF of this switch; calculate the sum of the right-side overcurrent reverse direction flag of the distribution terminal of this switch and the overcurrent reverse direction flags sent by all the right-side adjacent line switches received, to obtain the total right-side reverse overcurrent flag signal RNF of this switch;

[0234] Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the left side received by this switch distribution terminal to obtain the total left-side delay permission flag signal LOK; calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by this switch distribution terminal to obtain the total right-side delay permission flag signal ROK.

[0235] S562: Determine whether "LDF≥1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal has an action on the left-side pilot overcurrent protection and trips this switch; if it does not hold, further determine whether "RDF≥1, RNF = 0, ROK = the sum of the number of adjacent switches on the right side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal has an action on the right-side pilot overcurrent protection and trips this switch.

[0236] Embodiment Eight:

[0237] Figure 8 The following shows a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the eighth embodiment of this application, including the following steps:

[0238] S170: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0239] S270: According to the collected voltage and current, as well as the switch position, the distribution terminal obtains its respective pilot flag signals. The pilot flag signals include: delay permission flag OK, overcurrent flag OP, overcurrent positive direction flag, and overcurrent reverse direction flag. The overcurrent positive direction flag includes the left-side overcurrent positive direction flag LD, and the overcurrent reverse direction flag includes the left-side overcurrent reverse direction flag LN.

[0240] S370: When any one of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag, and the state of the delay permission flag signal of this switch distribution terminal changes, it sends the overcurrent flag, the left-side overcurrent positive direction flag, the left-side overcurrent reverse direction flag, and the delay permission flag to all the line switch distribution terminals adjacent to its left side.

[0241] S470: The distribution terminals configured for each switch of the distribution network line receive the states of the pilot flag signals sent by the adjacent line switch distribution terminals.

[0242] S570: Each distribution terminal configured for each switch of the distribution network line performs calculations for pilot overcurrent protection based on its own pilot flag signal and the pilot flag signals received from the adjacent line switch distribution terminals. Specifically, it includes:

[0243] S571. Calculate the total signals of various flags based on its own pilot flag signal and the received pilot flag signals of adjacent line switch distribution terminals, including:

[0244] Calculate the sum of the overcurrent flags of this switch distribution terminal and the overcurrent flags of all adjacent line switch distribution terminals on the left side received, to obtain the total left overcurrent flag signal LF;

[0245] Calculate the sum of the overcurrent positive direction flags of this switch distribution terminal for the left side and the overcurrent positive direction flags sent by all adjacent line switch distribution terminals on the left side received, to obtain the total left overcurrent positive direction flag signal LDF of this switch;

[0246] Calculate the sum of the overcurrent reverse direction flags of this switch distribution terminal for the left side and the overcurrent reverse direction flags sent by all adjacent line switch distribution terminals on the left side received, to obtain the total left overcurrent reverse direction flag signal LNF of this switch;

[0247] Calculate the sum of the delay permission flags of all adjacent line switch distribution terminals on the left side received by this switch distribution terminal, to obtain the total left delay permission flag signal LOK;

[0248] S572: Determine whether the pilot overcurrent protection direction judgment control word is enabled for the distribution terminal, that is, determine whether the pilot overcurrent protection direction judgment control word is 1. If not, execute step 563, that is, execute the pilot overcurrent protection logic without direction judgment. If so, execute step 564, that is, execute the pilot overcurrent protection logic with direction judgment;

[0249] S573: Perform the pilot overcurrent protection logic without direction judgment, and its specific steps are as follows:

[0250] Determine whether "LF = 1, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal for the left side acts, and this switch trips;

[0251] S574: Perform the pilot overcurrent protection logic with direction judgment, and its specific steps are as follows:

[0252] Determine whether "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that the pilot overcurrent protection of this switch distribution terminal for the left side acts, and this switch trips.

[0253] Example Nine:

[0254] Figure 9The following is a flowchart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the ninth embodiment of the present application, including the following steps:

[0255] S180: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0256] S280: According to the voltage and current collected by the distribution terminal, as well as the switch position, each obtains its own pilot flag signal. The pilot flag signal includes: delay permission flag OK, overcurrent flag OP, overcurrent forward direction flag, and overcurrent reverse direction flag. The overcurrent forward direction flag includes the right-side overcurrent forward direction flag RD, and the overcurrent reverse direction flag includes the right-side overcurrent reverse direction flag RN.

[0257] S380: When any one of the overcurrent flag, overcurrent forward direction flag, overcurrent reverse direction flag, and delay permission flag signal status of the distribution terminal of the present switch changes, the overcurrent flag, right-side overcurrent forward direction flag, right-side overcurrent reverse direction flag, and delay permission flag are sent to all the distribution terminals of the adjacent line switches on its right.

[0258] S480: The distribution terminals configured for each switch of the distribution network line receive the pilot flag signal status sent by the distribution terminals of the adjacent line switches.

[0259] S580: The distribution terminals configured for each switch of the distribution network line all perform calculations for pilot overcurrent protection according to their own pilot flag signals and the pilot flag signals received from the distribution terminals of the adjacent line switches. Specifically, it includes:

[0260] S581. According to its own pilot flag signal and the pilot flag signals received from the distribution terminals of the adjacent line switches on the right, calculate the total signal of various flags, including:

[0261] Calculate the sum of the overcurrent flag of the distribution terminal of the present switch and the overcurrent flags of all the distribution terminals of the adjacent line switches on the right received, to obtain the total right-side overcurrent flag signal RF;

[0262] Calculate the sum of the right-side overcurrent forward direction flag of the distribution terminal of the present switch and the overcurrent forward direction flags of all the distribution terminals of the adjacent line switches on the right received, to obtain the total right-side overcurrent direction flag signal RDF of the present switch;

[0263] Calculate the sum of the right-side overcurrent reverse direction flag of the distribution terminal of the present switch and the overcurrent reverse direction flags sent by all the distribution terminals of the adjacent line switches on the right received, to obtain the total right-side overcurrent reverse direction flag signal RNF of the present switch;

[0264] Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by this switch distribution terminal to obtain the total right-side delay permission flag signal ROK;

[0265] S582: Determine whether the pilot overcurrent protection direction judgment control word is enabled for the distribution terminal, that is, determine whether the pilot overcurrent protection direction judgment control word is 1. If not, execute step 563, that is, execute the pilot overcurrent protection logic without direction judgment. If so, execute step 564, that is, execute the pilot overcurrent protection logic with direction judgment;

[0266] S583: Perform the pilot overcurrent protection logic without direction judgment, and its specific steps are as follows:

[0267] Judge whether "RF = 1, ROK = the sum of the number of adjacent switches on the right side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that the switch distribution terminal of this switch performs a pilot overcurrent protection action on the right side and trips this switch;

[0268] S584: Perform the pilot overcurrent protection logic with direction judgment, and its specific steps are as follows:

[0269] Judge whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right side, and this state lasts for a time longer than the communication confirmation time T co " holds. If it holds, it is determined that the switch distribution terminal of this switch performs a pilot overcurrent protection action on the right side and trips this switch.

[0270] Embodiment Ten:

[0271] Figure 10 The figure shows a flow chart of a multi-terminal pilot overcurrent protection method for a distribution network line provided by the tenth embodiment of the present application, including the following steps:

[0272] S190: The distribution terminals configured for each switch of the distribution network line collect the line voltage and current, as well as the switch position.

[0273] S290: According to the voltage and current collected by the distribution terminal, as well as the switch position, obtain their respective pilot flag signals. The pilot flag signals include: delay permission flag OK, overcurrent flag OP, overcurrent positive direction flag, and overcurrent reverse direction flag. The overcurrent positive direction flag includes the left-side overcurrent positive direction flag LD and the right-side overcurrent positive direction flag RD, and the overcurrent reverse direction flag includes the left-side overcurrent reverse direction flag LN and the right-side overcurrent reverse direction flag RN.

[0274] S390: When any of the signal states of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag, and delay permission flag of this switch power distribution terminal changes, it sends the overcurrent flag, overcurrent positive direction flag to the left, overcurrent reverse direction flag to the left, and delay permission flag to all the line switch power distribution terminals adjacent to it on the left, and sends the overcurrent flag, overcurrent positive direction flag to the right, overcurrent reverse direction flag to the right, and delay permission flag to all the line switch power distribution terminals adjacent to it on the right.

[0275] S490: The power distribution terminals configured for each switch on the distribution network line receive the pilot flag signal states sent by the power distribution terminals of the adjacent line switches.

[0276] S590: Each power distribution terminal configured for each switch on the distribution network line calculates the pilot overcurrent protection based on its own pilot flag signal and the pilot flag signals received from the power distribution terminals of the adjacent line switches. Specifically, it includes:

[0277] S591. Calculate the total signal of various flags based on its own pilot flag signal and the pilot flag signals received from the power distribution terminals of the adjacent line switches, including:

[0278] Calculate the sum of the overcurrent flag of this switch power distribution terminal and the overcurrent flags of all the line switch power distribution terminals adjacent to it on the left to obtain the total left overcurrent flag signal LF; calculate the sum of the overcurrent flag of this switch power distribution terminal and the overcurrent flags of all the line switch power distribution terminals adjacent to it on the right to obtain the total right overcurrent flag signal RF;

[0279] Calculate the sum of the overcurrent positive direction flag to the left of this switch power distribution terminal and the overcurrent positive direction flags sent by all the line switch power distribution terminals adjacent to it on the left to obtain the total left overcurrent positive direction flag signal LDF of this switch; calculate the sum of the overcurrent positive direction flag to the right of this switch power distribution terminal and the overcurrent positive direction flags of all the line switch power distribution terminals adjacent to it on the right to obtain the total right overcurrent direction flag signal RDF of this switch;

[0280] Calculate the sum of the overcurrent reverse direction flag to the left of this switch power distribution terminal and the overcurrent reverse direction flags sent by all the line switch power distribution terminals adjacent to it on the left to obtain the total left overcurrent reverse direction flag signal LNF of this switch; calculate the sum of the overcurrent reverse direction flag to the right of this switch power distribution terminal and the overcurrent reverse direction flags sent by all the line switch power distribution terminals adjacent to it on the right to obtain the total right overcurrent reverse direction flag signal RNF of this switch;

[0281] Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the left side received by this switch distribution terminal to obtain the total left delay permission flag signal LOK; calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by this switch distribution terminal to obtain the total right delay permission flag signal ROK.

[0282] S592: Determine whether the pilot overcurrent protection direction judgment control word is enabled for the distribution terminal, that is, determine whether the pilot overcurrent protection direction judgment control word is 1. If not, execute step 563, that is, execute the pilot overcurrent protection logic without direction judgment. If so, execute step 564, that is, execute the pilot overcurrent protection logic with direction judgment.

[0283] S593: Perform the pilot overcurrent protection logic without direction judgment. The specific steps are as follows:

[0284] Judge whether "LF = 1, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal acts on the pilot overcurrent protection on the left side and trips this switch; if it does not hold, further judge whether "RF = 1, ROK = the sum of the number of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal acts on the pilot overcurrent protection on the right side and trips this switch.

[0285] S594: Perform the pilot overcurrent protection logic with direction judgment. The specific steps are as follows:

[0286] Judge whether "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal acts on the pilot overcurrent protection on the left side and trips this switch; if it does not hold, further judge whether "RDF ≥ 1, RNF = 0, ROK = the sum of the number of adjacent switches on the right side, and the duration of this state is greater than the communication confirmation time T co " holds. If it holds, it is determined that this switch distribution terminal acts on the pilot overcurrent protection on the right side and trips this switch.

[0287] In some embodiments, the distribution terminal may be provided with a power flow direction reversal control word DK. When the voltage and current of the distribution terminal follow the principle of power flow from the left side to the right side of the switch, DK is set to 0, and the overcurrent positive direction flag and the overcurrent reverse direction flag of the distribution terminal of this switch for the right side are calculated based on the actually collected voltage and current, and the overcurrent positive direction flag and the overcurrent reverse direction flag of the distribution terminal of this switch for the left side are calculated based on the actually collected voltage and the reversed current; when the voltage and current of the distribution terminal follow the principle of power flow from the right side to the left side of the switch, DK is set to 1, and the overcurrent positive direction flag and the overcurrent reverse direction flag of the distribution terminal of this switch for the right side are calculated based on the actually collected voltage and the reversed current, and the overcurrent positive direction flag and the overcurrent reverse direction flag of the distribution terminal of this switch for the left side are calculated based on the actually collected voltage and current.

[0288] In some embodiments, the distribution terminal is provided with a left-side pilot overcurrent protection control word LP and a right-side pilot overcurrent protection control word RP. When LP is set to 0, the distribution terminal will not execute the content related to the left-side pilot overcurrent protection. When RP is set to 0, the distribution terminal will not execute the content related to the right-side pilot overcurrent protection. It is recommended that LP of the distribution terminals configured for the distribution network switches directly connected to the substation on the left side and directly connected to the electrical load on the left side be set to 0, and it is recommended that RP of the distribution terminals configured for the distribution network switches directly connected to the substation on the right side and directly connected to the electrical load on the right side be set to 0.

[0289] Embodiment Eleven:

[0290] Combined with Figure 11Schematic diagram of fault distribution when the shown distribution network line is in open-loop operation. That is, when operating normally, the switches in the off position are connected to both sides. Taking this figure as an example, an RTDS test system is built to verify the pilot overcurrent protection logic that does not judge the direction of this application. Set the pilot overcurrent protection direction judgment control words of the distribution terminals configured for Switch #1 to Switch #6 to 0. Since the left side of Switch #1 is directly connected to the substation, set the pilot overcurrent protection control word of the distribution terminal of Switch #1 for the left side to 0. Since the right side of Switch #4 is directly connected to the substation, set the pilot overcurrent protection control word of the distribution terminal of Switch #4 for the right side to 0. Since the right side of Switch #5 is directly connected to the electrical load, set the pilot overcurrent protection control word of the distribution terminal of Switch #5 for the right side to 0. Since the right side of Switch #6 is directly connected to the electrical load, set the pilot overcurrent protection control word of the distribution terminal of Switch #6 for the right side to 0. Set a permanent metallic phase-to-phase short-circuit fault at position F1. The situation of the pilot overcurrent protection logic that does not judge the direction of each switch distribution terminal is shown in Table 1. Set a permanent metallic phase-to-phase short-circuit fault at position F2. The situation of the pilot overcurrent protection logic that does not judge the direction of each switch distribution terminal is shown in Table 2. In Table 1 and Table 2, LZL represents the action situation of the pilot overcurrent protection for the left side, and RZL represents the action situation of the pilot overcurrent protection for the right side.

[0291] As can be seen from Table 1, when a fault occurs at F1, the distribution terminals of Switch #2, Switch #3, Switch #5, and Switch #6 have action situations for the pilot overcurrent protection for the left side or the right side, that is, Switch #2, Switch #3, Switch #5, and Switch #6 are tripped, and the fault at F1 is accurately isolated.

[0292] As can be seen from Table 2, when a fault occurs at F2, the distribution terminals of Switch #3 and Switch #4 have action situations for the pilot overcurrent protection for the left side or the right side, that is, Switch #3 and Switch #4 are tripped, and the fault at F2 is accurately isolated.

[0293] Table 1 Situation of the pilot overcurrent protection logic that does not judge the direction when a fault occurs at F1

[0294] OP OK LF RF LOK ROK LZL RZL #1 Switch Distribution Terminal 1 1 1 2 0 1 Not Put into Use, No Action No Action #2 Switch Distribution Terminal 1 1 2 1 1 3 No Action Action, Trip #2 Switch #3 Switch Distribution Terminal 0 1 1 0 3 0 Action, Trip #3 Switch No Action #4 Switch Distribution Terminal 0 0 0 0 1 0 No Action No Action #5 Switch Distribution Terminal 0 1 1 0 3 0 Action, Trip #5 Switch Not Put into Use, No Action #6 Switch Distribution Terminal 0 1 1 0 3 0 Action, Trip #6 Switch Not Put into Use, No Action

[0295] Table 2 Situation of the pilot overcurrent protection logic that does not judge the direction when a fault occurs at F2

[0296] OP OK LF RF LOK ROK LZL RZL #1 Switch Distribution Terminal 0 0 0 0 0 0 Not Put into Use, No Action No Action #2 Switch Distribution Terminal 0 0 0 0 0 1 No Action No Action #3 Switch Distribution Terminal 0 1 0 1 0 1 No Action Action, Trip #3 Switch #4 Switch Distribution Terminal 1 1 1 1 1 0 Action, Trip #4 Switch Not Put into Use, No Action #5 Switch Distribution Terminal 0 0 0 0 1 0 No Action Not Put into Use, No Action #6 Switch Distribution Terminal 0 0 0 0 1 0 No Action Not Put into Use, No Action

[0297] Figure 12It is a schematic diagram of fault distribution when the distribution network line operates in a closed loop. Taking this figure as an example, an RTDS test system is built to verify the longitudinal overcurrent protection logic for direction judgment of the present invention. The longitudinal overcurrent protection direction judgment control words of the distribution terminals configured for Switch #1 to Switch #6 are set to 1. Since the left side of Switch #1 is directly connected to the substation, the longitudinal overcurrent protection control word of the distribution terminal of Switch #1 for the left side is set to 0. Since the right side of Switch #4 is directly connected to the substation, the longitudinal overcurrent protection control word of the distribution terminal of Switch #4 for the right side is set to 0. Since the right side of Switch #5 is directly connected to the electrical load, the longitudinal overcurrent protection control word of the distribution terminal of Switch #5 for the right side is set to 0. Since the right side of Switch #6 is directly connected to the electrical load, the longitudinal overcurrent protection control word of the distribution terminal of Switch #6 for the right side is set to 0. A permanent metal-phase short-circuit fault is set at the F1 position. The situation of the longitudinal overcurrent protection logic for direction judgment of each switch distribution terminal is shown in Table 3. A permanent metal-phase short-circuit fault is set at the F2 position. The situation of the longitudinal overcurrent protection logic for direction judgment of each switch distribution terminal is shown in Table 4. In Table 3 and Table 4, LZL represents the operation situation of the longitudinal overcurrent protection for the left side, and RZL represents the operation situation of the longitudinal overcurrent protection for the right side.

[0298] As can be seen from Table 3, when a fault occurs at F1, the distribution terminals of Switch #2, Switch #3, Switch #5, and Switch #6 have the operation situation of the longitudinal overcurrent protection for the left side or the right side, that is, Switch #2, Switch #3, Switch #5, and Switch #6 are tripped, and the fault at F1 is accurately isolated.

[0299] As can be seen from Table 4, when a fault occurs at F2, the distribution terminals of Switch #3 and Switch #4 have the operation situation of the longitudinal overcurrent protection for the left side or the right side, that is, Switch #3 and Switch #4 are tripped, and the fault at F2 is accurately isolated.

[0300] Table 3 Situation of the longitudinal overcurrent protection logic for direction judgment when a fault occurs at F1

[0301]

[0302] Table 4 Situation of the longitudinal overcurrent protection logic for direction judgment when a fault occurs at F2

[0303]

[0304] Note: It is recommended that when the method of the present invention is applied in actual engineering, based on the topology design drawings of the distribution network line, the left and right sides of the distribution network line switches are defined sequentially from one substation to the distribution network line side, as Figure 2 and Figure 3 shown. The voltage and current wiring of the corresponding switch distribution terminal is defaultly wired based on the principle that the power flow is from the left side to the right side of the switch. If it is connected reversely, the power flow direction inversion control word DK of the distribution terminal needs to be set to 1.

[0305] Embodiment Twelve:

[0306] Figure 13 As shown, the multi-terminal pilot overcurrent protection device 600 provided by the embodiment of the present application includes: an acquisition unit 601, a flag signal determination unit 602, a signal sending unit 603, a signal receiving unit 604, and a pilot overcurrent protection calculation unit 605.

[0307] The acquisition unit 601 is used to collect line voltage, current, and switch position through the distribution terminals configured for each switch of the distribution network line.

[0308] The flag signal determination unit 602 is used to obtain respective pilot flag signals according to the voltage and current collected by the distribution terminal and the switch position; the pilot flag signal includes: a delay permission flag and an overcurrent flag; or, the pilot flag signal includes: a delay permission flag, an overcurrent positive direction flag, and an overcurrent reverse direction flag; or, the pilot flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag, and an overcurrent reverse direction flag.

[0309] The overcurrent positive direction flag includes a left-side overcurrent positive direction flag or a right-side overcurrent positive direction flag, or includes both a left-side overcurrent positive direction flag and a right-side overcurrent positive direction flag; the overcurrent reverse direction flag includes a left-side overcurrent reverse direction flag or a right-side overcurrent reverse direction flag, or includes both a left-side overcurrent reverse direction flag and a right-side overcurrent reverse direction flag.

[0310] The signal sending unit 603 is used to send the state of the pilot flag signal related to the adjacent line to the adjacent line in response to the change in the state of any pilot flag signal of the distribution terminal of the present switch.

[0311] The signal receiving unit 604 receives the state of the pilot flag signal sent by the distribution terminal of the adjacent line switch through the distribution terminals configured for each switch of the distribution network line.

[0312] The pilot overcurrent protection calculation unit 605: The distribution terminals configured for each switch of the distribution network line all perform the calculation of pilot overcurrent protection according to their own pilot flag signals and the pilot flag signals of the distribution terminals of the adjacent line switches received.

[0313] The device performs functions similar to those provided by the previous method, and other functions can be referred to the previous description, which will not be elaborated here.

[0314] Figure 14The following is a structural diagram of an electronic device provided by the present application. It includes a processor and a memory. The memory stores computer instructions. When the computer instructions are executed by the processor, the processor executes the computer instructions to implement the method and refinement scheme as shown in Figures 1 - 10 the following.

[0315] It should be understood that the above device embodiments are merely illustrative, and the devices disclosed in the present invention can also be implemented in other ways. For example, the division of the above-mentioned units / modules is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units, modules or components can be combined, or can be integrated into another system, or some features can be ignored or not executed.

[0316] In addition, unless otherwise specified, in each embodiment of the present invention, each functional unit / module can be integrated in one unit / module, or each unit / module can exist physically alone, or two or more units / modules can be integrated together. The above integrated unit / module can be implemented in the form of hardware or in the form of a software program module.

[0317] When the above integrated unit / module is implemented in the form of hardware, the hardware can be a digital circuit, an analog circuit, etc. The physical implementation of the hardware structure includes but is not limited to transistors, memristors, etc. Unless otherwise specified, the processor or chip can be any suitable hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the on-chip cache, off-chip memory, and memory can be any suitable magnetic storage medium or magneto-optical storage medium, such as a resistive random access memory (RRAM), a dynamic random access memory (DRAM), a static random access memory (SRAM), an enhanced dynamic random access memory (EDRAM), a high-bandwidth memory (HBM), a hybrid memory cube (HMC), etc.

[0318] If the integrated unit / module is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a memory and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this disclosure. The aforementioned memory includes: various media such as USB flash drives, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), mobile hard disks, magnetic disks, or optical discs that can store program codes.

[0319] The embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to execute as Figure 2 the methods and refinement schemes shown.

[0320] It should be clearly understood that this application describes how to form and use specific examples, but this application is not limited to any details of these examples. Instead, based on the teachings of the content disclosed in this application, these principles can be applied to many other embodiments.

[0321] In addition, it should be noted that the above-mentioned drawings are only schematic illustrations of the processes included in the methods according to the exemplary embodiments of this application, rather than for limiting purposes. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the chronological order of these processes. Additionally, it is also easy to understand that these processes can be executed, for example, synchronously or asynchronously in multiple modules.

[0322] The above embodiments are only for illustrating the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modifications made on the basis of the technical solution according to the technical idea proposed by the present invention fall within the protection scope of the present invention.

Claims

1. A multi-terminal longitudinal overcurrent protection method for distribution network lines, characterized in that: include: Step 100: The distribution terminal configured for each switch of the distribution network line collects the line voltage and current, as well as the switch position; Step 200: obtaining respective longitudinal connection mark signals according to the collected voltage and current and switch positions of the power distribution terminals; The pilot connection flag signal includes: a delay permission flag and an overcurrent flag; or, the pilot connection flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag; or, the pilot connection flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag; The overcurrent positive direction mark includes a left overcurrent positive direction mark or a right overcurrent positive direction mark, or includes both a left overcurrent positive direction mark and a right overcurrent positive direction mark; the overcurrent reverse direction mark includes a left overcurrent reverse direction mark or a right overcurrent reverse direction mark, or includes both a left overcurrent reverse direction mark and a right overcurrent reverse direction mark; Step 300: in response to a change in the state of any pilot connection mark signal of the switch distribution terminal, sending the pilot connection mark signal state related to the adjacent line to the adjacent line; Step 400: the distribution terminal configured for each switch of the distribution network line receives the state of the longitudinal connection mark signal sent by the distribution terminal of the adjacent line switch; Step 500: The distribution terminal configured for each switch of the distribution network line calculates the longitudinal overcurrent protection according to its own longitudinal marking signal and the received longitudinal marking signal of the distribution terminal of the adjacent line switch.

2. The method according to claim 1, characterized in that The delay permission flag is recorded as OK. The phase voltage collected at the power distribution terminal is low voltage, that is, any phase voltage is lower than the phase voltage reduction judgment value U set1 , or the line voltage is low voltage, that is, any line voltage is lower than the line voltage reduction judgment value U set2 , or when the switch is detected to be in a jump position, the delay time T of the permission flag setting is passed ok Set the delay enable flag to 1, otherwise set it to 0; The overcurrent flag, denoted as OP, is when the effective value of any phase current collected at the distribution terminal is greater than the judgment value I of the overcurrent element of the distribution terminal. set If the overcurrent flag is set to 1, otherwise it is set to 0; The left overcurrent positive direction flag is recorded as LD. If the effective value of any phase current collected at the distribution terminal is greater than the judgment value I of the overcurrent element of the distribution terminal, set , and when the fault direction is determined to be a positive fault to the left through voltage and current, the positive direction flag of the left overcurrent is set to 1, otherwise it is set to 0; The right overcurrent positive direction flag is recorded as RD, and the effective value of any phase current collected at the distribution terminal is greater than the judgment value I of the overcurrent element of the distribution terminal. set , and when the fault direction is determined to be a positive fault to the right through voltage and current, the right overcurrent positive direction flag is set to 1, otherwise it is set to 0; The left overcurrent reverse direction flag is denoted as LN. When the effective value of any phase current collected at the distribution terminal is greater than the judgment value I of the overcurrent element of the distribution terminal, set , and when the fault direction is judged to be a reverse fault to the left side through voltage and current, the reverse direction flag of the left overcurrent is set to 1, otherwise it is set to 0; The right overcurrent reverse direction flag is denoted as RN. When the effective value of any phase current collected at the distribution terminal is greater than the judgment value I of the overcurrent element of the distribution terminal, set If the fault direction is determined to be a reverse fault to the right through voltage and current, the reverse direction flag for overcurrent on the right side is set to 1, otherwise it is set to 0.

3. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the pilot connection flag signal includes a delay permission flag and an overcurrent flag; When any of the overcurrent flag and delay permission flag signal states of the switch distribution terminal changes, the overcurrent flag and delay permission flag are sent to all adjacent line switch distribution terminals on its left and / or right sides.

4. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a left overcurrent positive direction flag, and the overcurrent reverse direction flag includes a left overcurrent reverse direction flag; When any of the overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the left side overcurrent positive direction flag, left side overcurrent reverse direction flag and delay permission flag are sent to all the adjacent line switch distribution terminals on its left side.

5. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a right-side overcurrent positive direction flag, and the overcurrent reverse direction flag includes a right-side overcurrent reverse direction flag; When any of the overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the right-side overcurrent positive direction flag, right-side overcurrent reverse direction flag and delay permission flag are sent to all adjacent line switch distribution terminals on its right side.

6. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a left overcurrent positive direction flag and a right overcurrent positive direction flag, and the overcurrent reverse direction flag includes a left overcurrent reverse direction flag and a right overcurrent reverse direction flag; When any of the overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the overcurrent positive direction flag on the left side, the overcurrent reverse direction flag on the left side and the delay permission flag are sent to all the adjacent line switch distribution terminals on its left side, and the overcurrent flag, the overcurrent positive direction flag on the right side, the overcurrent reverse direction flag on the right side and the delay permission flag are sent to all the adjacent line switch distribution terminals on the right side.

7. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a left overcurrent positive direction flag, and the overcurrent reverse direction flag includes a left overcurrent reverse direction flag; When any of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the overcurrent flag, the left overcurrent positive direction flag, the left overcurrent reverse direction flag and the delay permission flag are sent to all the adjacent line switch distribution terminals on its left side.

8. The method according to claim 1, characterized in that In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a right-side overcurrent positive direction flag, and the overcurrent reverse direction flag includes a right-side overcurrent reverse direction flag; When any of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the overcurrent flag, the right-side overcurrent positive direction flag, the right-side overcurrent reverse direction flag and the delay permission flag are sent to all adjacent line switch distribution terminals on its right side.

9. The method according to claim 1, characterized in that: In response to a change in the state of any pilot connection mark signal of the switch power distribution terminal, the state of the pilot connection mark signal related to the adjacent line is sent to the adjacent line, specifically including: When the longitudinal connection flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag, the overcurrent positive direction flag includes a left overcurrent positive direction flag and a right overcurrent positive direction flag, and the overcurrent reverse direction flag includes a left overcurrent reverse direction flag and a right overcurrent reverse direction flag; When any of the overcurrent flag, overcurrent positive direction flag, overcurrent reverse direction flag and delay permission flag signal states of this switch distribution terminal changes, the overcurrent flag, the overcurrent positive direction flag on the left, the overcurrent reverse direction flag on the left and the delay permission flag are sent to all adjacent line switch distribution terminals on its left, and the overcurrent flag, the overcurrent positive direction flag on the right, the overcurrent reverse direction flag on the right and the delay permission flag are sent to all adjacent line switch distribution terminals on its right.

10. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Calculate the total signal of each type of mark according to its own longitudinal mark signal and the received longitudinal mark signal of the adjacent line switch distribution terminal; Whether the longitudinal overcurrent protection is actuated is determined based on the signals of the various signs.

11. The method according to claim 1, characterized in that: The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 511, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the left adjacent line switch distribution terminals received, and obtain the total LF of the left overcurrent flag signal; Calculate the sum of the delay permission flags of all the line switch distribution terminals on the left side received by the switch distribution terminal to obtain the total LOK of the delay permission flag signal on the left side; Step 512: Determine whether "LF = 1, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "If it is true, it is determined that the power distribution terminal of this switch is in action for the left longitudinal overcurrent protection, and this switch is tripped.

12. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 521, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the power distribution terminal of the switch and the overcurrent flags of all the power distribution terminals of the adjacent lines on the right side to obtain the total RF of the overcurrent flag signal on the right side; Calculate the sum of the delay permission flags of all the adjacent line switch distribution terminals on the right side received by the switch distribution terminal to obtain the total right side delay permission flag signal ROK; Step 522: Determine if "RF = 1, ROK = the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

13. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 531, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the line switch distribution terminals received on the left side, and obtain the total LF of the overcurrent flag signal on the left side; calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the line switch distribution terminals received on the right side, and obtain the total RF of the overcurrent flag signal on the right side; Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the left side received by the switch distribution terminal to obtain the total delay permission flag signal LOK on the left side; calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by the switch distribution terminal to obtain the total delay permission flag signal ROK on the right side; Step 532: Determine whether "LF = 1, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "Whether it is established, if it is established, it is determined that the switch distribution terminal has acted on the left longitudinal overcurrent protection and tripped the switch; if it is not established, it is further determined that "RF=1, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

14. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 541, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent positive direction flag on the left side of the switch distribution terminal pair and the overcurrent positive direction flags received from all the left adjacent line switch distribution terminals to obtain the total LDF of the overcurrent positive direction flag signal on the left side of the switch pair; Calculate the sum of the left overcurrent reverse direction flag of the switch distribution terminal pair and the overcurrent reverse direction flags received from all the left adjacent line switch distribution terminals to obtain the total LNF of the left overcurrent reverse direction flag signal of the switch pair; Calculate the sum of the delay permission flags of all the line switch distribution terminals on the left side received by the switch distribution terminal to obtain the total LOK of the delay permission flag signal on the left side; Step 542: Determine whether "LDF≥1, LNF=0, LOK=the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "If it is true, it is determined that the power distribution terminal of this switch is in action for the left longitudinal overcurrent protection, and this switch is tripped.

15. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 551, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the right-side overcurrent positive direction flag of the switch distribution terminal pair and the received right-side adjacent line switch distribution terminal overcurrent positive direction flags to obtain the total RDF of the right-side overcurrent direction flag signal of the switch pair; Calculate the sum of the right-side overcurrent reverse direction flag of the switch distribution terminal pair and the overcurrent reverse direction flags received from all the right-side adjacent line switch distribution terminals to obtain the total RNF of the right-side reverse direction overcurrent flag signal of the switch pair; Calculate the sum of the delay permission flags of all the adjacent line switch distribution terminals on the right side received by the switch distribution terminal to obtain the total right side delay permission flag signal ROK; Step 552: Determine if "RDF≥1, RNF=0, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

16. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 561, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent positive direction sign on the left side of the switch distribution terminal pair and the overcurrent positive direction sign received from all the left adjacent line switch distribution terminals to obtain the total LDF of the left overcurrent positive direction sign signal of the switch pair; calculate the sum of the overcurrent positive direction sign on the right side of the switch distribution terminal pair and the overcurrent positive direction sign received from all the right adjacent line switch distribution terminals to obtain the total RDF of the right overcurrent direction sign signal of the switch pair; Calculate the sum of the overcurrent reverse direction flag on the left side of the switch distribution terminal pair and the overcurrent reverse direction flag received from all the left adjacent line switch distribution terminals to obtain the total LNF of the left overcurrent reverse direction flag signal of the switch pair; calculate the sum of the overcurrent reverse direction flag on the right side of the switch distribution terminal pair and the overcurrent reverse direction flag received from all the right adjacent line switch distribution terminals to obtain the total RNF of the right reverse direction overcurrent flag signal of the switch pair; Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the left side received by the switch distribution terminal to obtain the total delay permission flag signal LOK on the left side; calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by the switch distribution terminal to obtain the total delay permission flag signal ROK on the right side; Step 562: Determine whether "LDF≥1, LNF=0, LOK=the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co If it is established, the switch distribution terminal is determined to be on the left longitudinal overcurrent protection action, and the switch is tripped; if it is not established, it is further determined that "RDF≥1, RNF=0, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

17. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 571, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the left adjacent line switch distribution terminals received, and obtain the total LF of the left overcurrent flag signal; Calculate the sum of the overcurrent positive direction flag on the left side of the switch distribution terminal pair and the overcurrent positive direction flags received from all the left adjacent line switch distribution terminals to obtain the total LDF of the overcurrent positive direction flag signal on the left side of the switch pair; Calculate the sum of the left overcurrent reverse direction flag of the switch distribution terminal pair and the overcurrent reverse direction flags received from all the left adjacent line switch distribution terminals to obtain the total LNF of the left overcurrent reverse direction flag signal of the switch pair; Calculate the sum of the delay permission flags of all the line switch distribution terminals on the left side received by the switch distribution terminal to obtain the total LOK of the delay permission flag signal on the left side; Step 572: determine whether the power distribution terminal is in the longitudinal overcurrent protection direction control word, that is, determine whether the longitudinal overcurrent protection direction control word is 1. If not, execute step 563, that is, execute the longitudinal overcurrent protection logic without direction determination. If yes, execute step 564, that is, execute the longitudinal overcurrent protection logic with direction determination. Step 573: Perform the longitudinal overcurrent protection logic without judging the direction, and the specific steps are as follows: Judge "LF=1, LOK=the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "Whether it is established, if it is established, it is determined that the power distribution terminal of this switch is in action for the left longitudinal overcurrent protection, and the switch is tripped; Step 574: Perform the longitudinal overcurrent protection logic to determine the direction. The specific steps are as follows: Determine "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "If it is true, it is determined that the power distribution terminal of this switch is in action for the left longitudinal overcurrent protection, and this switch is tripped.

18. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 581, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the power distribution terminal of the switch and the overcurrent flags of all the power distribution terminals of the adjacent lines on the right side to obtain the total RF of the overcurrent flag signal on the right side; Calculate the sum of the right-side overcurrent positive direction flag of the switch distribution terminal pair and the received right-side adjacent line switch distribution terminal overcurrent positive direction flags to obtain the total RDF of the right-side overcurrent direction flag signal of the switch pair; Calculate the sum of the overcurrent reverse direction flag on the right side of the switch distribution terminal pair and the overcurrent reverse direction flags received from all the right adjacent line switch distribution terminals to obtain the total RNF of the overcurrent reverse direction flag signal on the right side of the switch pair; Calculate the sum of the delay permission flags of all the adjacent line switch distribution terminals on the right side received by the switch distribution terminal to obtain the total right side delay permission flag signal ROK; Step 582: Determine whether the power distribution terminal is in the longitudinal overcurrent protection direction control word, that is, determine whether the longitudinal overcurrent protection direction control word is 1. If not, execute step 563, that is, execute the longitudinal overcurrent protection logic without direction determination. If yes, execute step 564, that is, execute the longitudinal overcurrent protection logic with direction determination. Step 583: Perform the longitudinal overcurrent protection logic without judging the direction, and the specific steps are as follows: Judge "RF=1, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "Whether it is established, if it is established, it is determined that the power distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and the switch is tripped; Step 584: Perform the longitudinal overcurrent protection logic to determine the direction. The specific steps are as follows: Judge "RDF≥1, RNF=0, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

19. The method according to claim 1, characterized in that The distribution terminal configured for each switch of the distribution network line performs calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch, specifically including: Step 591, according to its own longitudinal connection mark signal and the received longitudinal connection mark signal of the adjacent line switch distribution terminal, calculate the signal sum of various marks, including: Calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the line switch distribution terminals received on the left side, and obtain the total LF of the overcurrent flag signal on the left side; calculate the sum of the overcurrent flag of the switch distribution terminal and the overcurrent flags of all the line switch distribution terminals received on the right side, and obtain the total RF of the overcurrent flag signal on the right side; Calculate the sum of the overcurrent positive direction sign on the left side of the switch distribution terminal pair and the overcurrent positive direction sign received from all the left adjacent line switch distribution terminals to obtain the total LDF of the left overcurrent positive direction sign signal of the switch pair; calculate the sum of the overcurrent positive direction sign on the right side of the switch distribution terminal pair and the overcurrent positive direction sign received from all the right adjacent line switch distribution terminals to obtain the total RDF of the right overcurrent direction sign signal of the switch pair; Calculate the sum of the overcurrent reverse direction flag on the left side of the switch distribution terminal pair and the overcurrent reverse direction flag received from all the left adjacent line switch distribution terminals to obtain the total LNF of the left overcurrent reverse direction flag signal of the switch pair; calculate the sum of the overcurrent reverse direction flag on the right side of the switch distribution terminal pair and the overcurrent reverse direction flag received from all the right adjacent line switch distribution terminals to obtain the total RNF of the right overcurrent reverse direction flag signal of the switch pair; Calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the left side received by the switch distribution terminal to obtain the total delay permission flag signal LOK on the left side; calculate the sum of the delay permission flags of all the line switch distribution terminals adjacent to the right side received by the switch distribution terminal to obtain the total delay permission flag signal ROK on the right side; Step 592: Determine whether the power distribution terminal is in the longitudinal overcurrent protection direction control word, that is, determine whether the longitudinal overcurrent protection direction control word is 1. If not, execute step 563, that is, execute the longitudinal overcurrent protection logic without direction determination. If yes, execute step 564, that is, execute the longitudinal overcurrent protection logic with direction determination. Step 593: Perform the longitudinal overcurrent protection logic without judging the direction, and the specific steps are as follows: Judge "LF=1, LOK=the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co "Whether it is established, if it is established, it is determined that the switch distribution terminal has acted on the left longitudinal overcurrent protection and tripped the switch; if it is not established, it is further determined that "RF=1, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "Whether it is established, if it is established, it is determined that the power distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and the switch is tripped; Step 594: Perform the longitudinal overcurrent protection logic to determine the direction. The specific steps are as follows: Determine "LDF ≥ 1, LNF = 0, LOK = the sum of the number of adjacent switches on the left, and the duration of this state is greater than the communication confirmation time T co If it is established, the switch distribution terminal is determined to be on the left longitudinal overcurrent protection action, and the switch is tripped; if it is not established, it is further determined that "RDF≥1, RNF=0, ROK=the sum of the number of adjacent switches on the right, and the duration of this state is greater than the communication confirmation time T co "If it is established, it is determined that the distribution terminal of this switch is in action for the right longitudinal overcurrent protection, and this switch is tripped.

20. The method according to claim 2, characterized in that The overcurrent element determines the constant value I set Greater than the maximum load current of the distribution network line.

21. The method according to claim 2, characterized in that The phase voltage decreases to determine the constant value U set1 The value range is 0 set1 h1 , where U h1 It is the phase voltage rating of the distribution network line.​​ 22. The method according to claim 2, characterized in that The line voltage decreases to determine the fixed value U set2 The value range is 0 set2 h2 , where U h2 It is the line voltage rating of the distribution network line.​​ 23. The method according to claim 2, characterized in that The setting delay of the permission flag is T ok The setting principle is to avoid the phase voltage being low or the line voltage being low before the overcurrent mark is generated when a short circuit fault occurs in the distribution network line.

24. The method according to any one of claims 10 to 19, characterized in that: The communication confirmation time Tco is the designed delay when constructing the communication channel between adjacent switch distribution terminals.

25. A multi-terminal longitudinal overcurrent protection device for a distribution network, characterized in that: include: A collection unit, a flag signal determination unit, a signal sending unit, a signal receiving unit and a longitudinal overcurrent protection calculation unit; wherein: The acquisition unit is used to acquire line voltage and current, as well as switch position, through the distribution terminals configured by each switch of the distribution network line; The flag signal determination unit is used to obtain respective longitudinal flag signals according to the voltage and current collected by the power distribution terminal and the switch position; the longitudinal flag signal includes: a delay permission flag and an overcurrent flag; or, the longitudinal flag signal includes: a delay permission flag, an overcurrent positive direction flag and an overcurrent reverse direction flag; or, the longitudinal flag signal includes: a delay permission flag, an overcurrent flag, an overcurrent positive direction flag and an overcurrent reverse direction flag; The overcurrent positive direction mark includes a left overcurrent positive direction mark or a right overcurrent positive direction mark, or includes both a left overcurrent positive direction mark and a right overcurrent positive direction mark; The overcurrent reverse direction mark includes a left overcurrent reverse direction mark or a right overcurrent reverse direction mark, or includes both a left overcurrent reverse direction mark and a right overcurrent reverse direction mark; The signal sending unit is used to send the state of the pilot connection mark signal related to the adjacent line to the adjacent line in response to the change of the state of any pilot connection mark signal of the switch distribution terminal; The signal receiving unit, the distribution terminal configured for each switch of the distribution network line receives the longitudinal connection mark signal status sent by the distribution terminal of the adjacent line switch; The longitudinal overcurrent protection calculation unit: the distribution terminal configured with each switch of the distribution network line performs the calculation of the longitudinal overcurrent protection according to its own longitudinal flag signal and the received longitudinal flag signal of the distribution terminal of the adjacent line switch.

26. An electronic device, characterized in that: It comprises a processor and a memory, wherein the memory stores a program, and the program can be loaded by the processor to execute the method as claimed in any one of claims 1 to 24.

27. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 24 is implemented.

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