Intelligent switch remote power distribution regulation method based on measurement data

Abstract

The application discloses a smart switch remote power distribution regulation method based on measurement data, relates to the field of switch power distribution regulation, and comprises the following steps: electrical measurement data of each smart switch is acquired, when abnormal mutation of electrical quantity is detected, the power supply mode is recognized according to the switch state, the tie-in switch is marked, the disturbance transmission path is tracked according to the power direction, the power supply mode and the tie-in switch position, when a fault occurs in a feeder, the fault point can be accurately located and the boundary switch closest to the fault point is selected to form a candidate set through the cooperative matching and path tracking between switches, the candidate set is verified through combination, the combination with the minimum comprehensive cost is selected, the optimal isolation scheme is determined by taking the minimum number of action switches as the optimization standard, the disturbance transmission path is re-recognized according to new measurement data after the isolation is successful, the iteration number is accumulated, the reclosing is locked out and the dead zone warning is triggered when the disturbance transmission path repeatedly appears, and the multi-switch cooperative linkage and real-time working condition adaptive regulation are realized.

Description

Technical Field

[0001] This invention belongs to the field of switch power distribution control technology, and relates to a method for intelligent switch remote power distribution control based on measurement data. Background Technology

[0002] With the advancement of smart grid construction, the level of automation in distribution networks is constantly improving. As the core execution equipment for fault detection, isolation and power restoration in the power distribution system, the application scope of smart switches has been extended from substations to feeder lines and user sides.

[0003] In the prior art, such as the invention patent with publication number CN114256985A, a low-voltage power distribution switch system based on the Internet of Things is proposed. By setting up a measurement and control module and a communication module, the measurement results of each smart switch are transmitted to the network terminal, realizing the monitoring of the operating status of each smart switch and data uploading.

[0004] For example, the invention patent with publication number CN115833118A proposes a method and system for controlling power distribution switches for power equipment. It constructs a scheme database based on historical power distribution demand information, matches multiple candidate schemes according to the current power distribution demand, obtains the optimal scheme through optimization, and then adjusts the switches whose current control state does not match the target.

[0005] However, while the above scheme achieves the effect of remote power distribution control of intelligent switches, it still has the following shortcomings: First, each switch in the above scheme can only operate independently based on its own measurement data. However, upstream and downstream switches in the distribution network affect each other, and adjusting the opening and closing status of a certain switch may cause cascading changes in voltage and power flow. When a feeder fault occurs, if only a single switch is relied upon to independently judge and execute the opening operation, the lack of upstream and downstream coordination may lead to incomplete fault isolation and an expansion of the power outage area.

[0006] Furthermore, matching solutions based on historical data cannot adapt to real-time changes in operating conditions. Power grid operation is affected by various factors such as weather, seasons, and unforeseen events, resulting in complex and variable operating conditions. Historical databases cannot cover all possible operating scenarios, potentially leading to unreasonable matching results or even the absence of usable solutions. Moreover, when the distribution network structure changes, such as the addition of distributed power sources or line upgrades, the solution database built on historical data becomes completely invalid, requiring the accumulation of new data to establish a new solution database. During this period, control capabilities are lost. Summary of the Invention

[0007] In view of this, in order to solve the problems mentioned in the background art, the present invention provides a method for remote power distribution control of intelligent switches based on measurement data.

[0008] The objective of this invention can be achieved through the following technical solution: a remote power distribution control method for intelligent switches based on measurement data, comprising: acquiring electrical measurement data of each intelligent switch, identifying the power supply mode and marking the interconnection switch according to the switch status when detecting abnormal sudden changes in electrical quantities.

[0009] The disturbance propagation path is traced based on the power direction and power supply mode, and the location of the tie switch is used as the tracing boundary. When the power direction is ambiguous, the search range is expanded to the two adjacent switches.

[0010] When a feeder fault occurs, the fault point is traced back along the disturbance propagation path to each power source to determine the boundary switches of the fault point and form a candidate set. If there is only one power source and no tie switch, the upstream switch is isolated from the candidate set.

[0011] For the selection of sets and combinations, the combination with the lowest overall cost is selected. The main grid side and the distributed power supply side are executed simultaneously according to the principle of coordinated circuit breaking. The selected combination must disconnect the fault point from all power supply paths. The non-faulty area relies on the marked tie switch to restore power supply to obtain the action sequence and send it out for execution.

[0012] After execution, a confirmation is sent back. If the operation is not fully successful within a timeout period, the system will jump to the upstream backup and issue a warning. If the operation is successful, the path will be re-identified and the number of iterations will be accumulated. If the same fault point occurs repeatedly, the reclosing will be blocked and a dead zone warning will be triggered.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention obtains electrical measurement data of each smart switch, detects abnormal changes in electrical quantity, identifies the power supply mode and marks the interconnection switch according to the switch state, and tracks the disturbance transmission path according to the power direction combined with the power supply mode and the position of the interconnection switch, thereby realizing the accurate determination of the source direction of the fault disturbance and the complete tracking of the propagation path.

[0014] (2) When a feeder fails, the present invention can accurately locate the fault point and select the boundary switches adjacent to the fault point to form a candidate set through the coordinated cooperation and path tracking between the switches. This allows the selected combination to cut off the electrical connection path between the fault point and all power sources, avoiding the problem of incomplete isolation and expanded power outage range caused by independent judgment of a single switch, and improving the efficiency of power supply restoration.

[0015] (3) The present invention determines the optimal isolation scheme by performing combination verification on the candidate set and selecting the combination with the minimum comprehensive cost, with the minimum number of action switches as the preferred criterion. It does not rely on historical databases for scheme matching, but rather performs dynamic analysis and online decision-making based on real-time collected switch status and measurement data.

[0016] (4) After successful isolation, the present invention re-identifies the disturbance transmission path and counts the number of iterations based on the new measurement data. When the disturbance recurs, it blocks the reclosing and triggers a dead zone warning. It can respond in real time according to the actual operating status of the distribution network, avoiding the problem of unreasonable matching and lack of control capability due to the lack of corresponding scenarios in the database. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a diagram illustrating the implementation steps of the method of the present invention;

[0019] Figure 2 This is a flowchart of the disturbance propagation path tracing process of the present invention;

[0020] Figure 3 This is a flowchart of the fault execution feedback and iterative processing of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 As shown, the present invention provides a remote power distribution control method for intelligent switches based on measurement data, including: S1, acquiring electrical measurement data of each intelligent switch, and identifying the power supply mode and marking the interconnection switch according to the switch status when detecting abnormal sudden changes in electrical quantities.

[0023] The steps for obtaining electrical measurement data of each smart switch are as follows: First, a measurement data request frame is sent to each smart switch through the communication network. The telemetry data message sent by each switch is received. After data integrity verification and timestamp verification, the fundamental effective value and instantaneous sampled value sequence of phase current, zero-sequence current and phase voltage at each switch are extracted. At the same time, the remote signaling data packet sent by each smart switch is read. After anti-jitter confirmation, the opening and closing status flag bits are extracted.

[0024] The specific implementation steps for detecting abnormal changes in electrical quantities are as follows: The power distribution control master station uses the power frequency cycle as the calculation window, obtains the effective value of each electrical quantity in the current window, and extracts the effective value of the electrical quantity at the same phase in the previous power frequency cycle, and calculates the absolute value of the difference between the two as the change quantity; the electrical quantities include at least phase current, zero-sequence current and phase voltage.

[0025] Alternatively, the adjacent sampling point difference method can be used to obtain the current sampling value sequence within the detection period in units of the detection period. The absolute value of the difference between adjacent sampling points is calculated in turn, and the maximum value is taken as the second mutation amount within the detection period.

[0026] When the first or second mutation amount exceeds the corresponding mutation threshold, an abnormal mutation in the corresponding electrical quantity is initially determined. To avoid misjudgment caused by normal load fluctuations or measurement noise, a further confirmation process is adopted to verify the preliminary judgment result, as follows: A duration condition is set, and when the electrical quantity mutation amount reaches the time threshold, it is confirmed as a valid abnormal mutation. Preferably, the time threshold is set to 20 milliseconds to confirm the duration condition of the abnormal electrical quantity mutation.

[0027] The mutation thresholds corresponding to the various electrical quantities are determined as follows: Under the normal operating conditions of the distribution network, the normal operating data of each electrical quantity are continuously collected within a preset time period, the absolute value of the difference between each electrical quantity and adjacent power frequency cycles is calculated, and the maximum value is taken as the mutation threshold of the corresponding electrical quantity.

[0028] The length of the preset time period is determined as follows: The average daily load value of the monitored line during continuous operation is obtained. The load values ​​of three adjacent days are compared sequentially. If the load value of a certain day is greater than both the previous and next day, that day is marked as a local maximum point; if the load value of a certain day is equal to either the previous or next day, that day is marked as a local minimum point. The time intervals between adjacent local maximum and minimum points are calculated, and the arithmetic mean of all time intervals is taken as the length of the preset time period. If there is no historical load data for the monitored line, data is continuously collected after the line is put into operation until at least three local maximum and minimum points are generated, and then the length is determined using the above method.

[0029] Because the opening and closing status of each smart switch in the power distribution network reflects the actual composition of the current electrical connection path in real time, but the switch status itself is only an expression of the on / off state of a single node, and cannot directly represent the power distribution and connection node location of the entire area.

[0030] Therefore, the specific implementation of identifying the power supply mode and marking the interconnection switch based on the switch status is as follows: read the open / closed status of each smart switch, and record the switch in the closed state as the circuit node and the switch in the open state as the circuit breaker node.

[0031] The above-mentioned reading of the opening and closing status of each smart switch is specifically as follows: The power distribution control master station acquires the remote signaling data packets sent by each smart switch through the communication network at a fixed sampling period. After data integrity verification and timestamp verification, the opening and closing status identifier bits are extracted. To avoid misjudgment of status due to communication jitter, a 50-millisecond anti-jitter confirmation is performed on the status change signal. Only the confirmed status can be used.

[0032] It should be added that if the switch state is in an intermediate state or data is missing, it will be forcibly defaulted to an open circuit node and a warning will be generated.

[0033] Starting from the main power grid power source side, query each power supply path. If only one main power grid power source reaches all loads, it is a single power source radiation mode. If two or more main power grid power sources reach the loads, it is a multi-power source power supply mode.

[0034] Specifically, taking the main power grid power supply side bus as the starting node, the switches directly connected to the bus and in the closed state are used as the search starting point. A depth-first search is adopted to trace downstream step by step along the closed switch path. The specific steps are as follows: Starting from the current node, initially the main power grid power supply side bus, the search proceeds downstream along any unvisited adjacent switch in the closed state to the next node until the load node is reached or the search cannot continue. Then, the search stops in this direction. The search then returns to the previous node and continues to search for whether there are other unvisited adjacent switches in the closed state at this node. If they exist, the search proceeds in the new direction. If they do not exist, the search continues to return. The above process is repeated until the search returns to the starting node and all adjacent switches have been visited. At this point, the search of all power supply paths is completed. For distribution networks with ring network structures, a visit mark is added to each visited node during the search process. When the search encounters a marked node, it will not be visited again to prevent infinite loops.

[0035] The main power grid power source refers to the power source of the large power grid on the bus side of the substation. Distributed power sources are not involved in the determination during the power supply mode identification stage.

[0036] During normal operation, the distribution network maintains an open-loop operation, meaning that any load at any given time is supplied by only one power source through a single path, and this path is determined by the open / closed status of each switch. Therefore, by searching along closed switches from the main power source, the range of loads that can be reached is the actual power supply range of that power source.

[0037] When a switch is in an open state and its two sides are connected to different power supplies, it is marked as a tie switch.

[0038] In a distribution network, a tie switch serves as a bridge connecting two different feeders or different power supply areas. Under normal circumstances, it is in the open state to maintain the open-loop operation of the power grid, with each side connected to a different power supply. Therefore, when a tie switch in the open state can be traced back to a different power supply on both sides, it can be identified as a tie switch with load transfer capability.

[0039] Before entering the tracking disturbance propagation path, the distribution control master station first obtains the current count value of the iteration counter corresponding to the current fault event and compares the current count value with the maximum number of iterations: if the current count value is greater than or equal to the maximum number of iterations, the current fault is determined to be a persistent permanent fault, the reclosing function of the corresponding line is directly blocked, a dead zone warning signal is triggered and reported to the distribution control master station's human-machine interface, and the current fault handling process is terminated without executing subsequent steps; if the current count value is less than the maximum number of iterations, step S2 is allowed to continue.

[0040] S2. Track the disturbance transmission path based on the power direction and power supply mode, and use the position of the tie switch as the tracing boundary. When the power direction is ambiguous, expand the search range to the two adjacent switches.

[0041] When a power distribution system malfunctions, abnormal changes in electrical quantities will propagate along the power supply path. However, each smart switch can only detect changes in electrical quantities at its own installation location. If only the change information from a single switch is relied upon, it is impossible to determine the direction of the disturbance source or to distinguish whether the change comes from the power supply on this side or the feeder on the opposite side.

[0042] See Figure 2 As shown, the above-mentioned steps for tracking the transmission path of disturbances are as follows: the switch that detects the abnormal change in electrical quantity is taken as the starting switch, and the phase difference between the voltage and current at the starting switch is read. If the phase difference is within the lag range, the power flows in the forward direction; if it is within the leading range, the power flows in the reverse direction.

[0043] The voltage and current phasors are acquired by voltage and current transformers installed at the starting switch. The fundamental phasor is extracted via Fourier transform, and harmonic components and high-frequency noise are filtered out before subtraction. The lag and lead ranges are determined as follows: The distribution line is resistive-inductive. During normal operation, the load current lags the voltage, with a phase difference between 0° and 90°. Power flows from the power source to the load side; therefore, this range is defined as the positive lag range. When distributed generation feeds back to the grid, the current leads the voltage, with a phase difference between -90° and 0°. Power flows from the load side to the power source side; therefore, this range is defined as the negative lead range.

[0044] The side to which power flows into the current switch is marked as the upstream side, and the side to which power flows out of the current switch is marked as the downstream side. The switch electrically connected to the upstream side of the current switch is marked as the upstream switch, and the switch electrically connected to the downstream side is marked as the downstream switch.

[0045] Specifically, the current switch has a first port and a second port, which are respectively connected to the power distribution lines on both sides. The upstream side and the downstream side refer to the two port directions of the current switch. When power flows in from the first port and out from the second port, the first port side is the upstream side and the second port side is the downstream side. If the power directions are opposite, the upstream and downstream sides are interchanged.

[0046] The specific connection relationship of the switches electrically connected to the upstream side of the current switch is as follows: search outwards along the upstream port of the current switch, read the adjacent switches that are directly electrically connected to the port and are in the closed state, and mark the switches as upstream switches; the marking method for downstream switches is the same.

[0047] Starting from the starting switch, trace along the power direction. After determining the power direction at each switch, continue forward until reaching the power supply side or the tie switch position. Connect the switches in sequence to generate a disturbance transmission path.

[0048] By tracing the disturbance propagation path as described above, a complete path chain is established between the detected abrupt change and the power supply side, clarifying the direction of the disturbance source and avoiding misjudgments caused by ambiguous power direction or backflow current from distributed power sources. Furthermore, tracing terminates at the tie switch boundary to prevent the path from diverging to non-faulty feeders, thereby narrowing the search range for subsequent fault location.

[0049] Because when a short circuit occurs near the fault point, the voltage and current tend to be in phase, or when the line is purely capacitive, the phase difference tends to be ±90 degrees, the power direction at a single point cannot be clearly determined, leading to the interruption of tracing; at the same time, the tie switch is the electrical boundary between different feeders, and tracing should not cross it.

[0050] Therefore, the above-mentioned expansion of the search range to two adjacent switches when the power direction is ambiguous includes: when the absolute value of the phase difference between the starting switches is less than the set discrimination angle, the power direction is determined to be ambiguous, and the two adjacent switches before and after are included in the search.

[0051] The set discrimination angle is determined as follows: the value of the discrimination angle is determined based on the measurement error range of the voltage transformer and current transformer at the smart switch. Specifically, for scenarios with transformer factory accuracy parameters, the ratio error and angle error parameters of the transformer are read, the maximum phase measurement error of the two is calculated, and the set discrimination angle value is greater than the maximum phase measurement error. For application scenarios without transformer accuracy parameters, the phase measurement error of equipment of the same type and voltage level under standard configuration is used as the initial discrimination angle estimate. If the set discrimination angle is too large, the discrimination angle is gradually reduced until the proportion of clear power direction determination returns to normal; if the set discrimination angle is too small, the discrimination angle is gradually increased until the judgment error rate is lower than the total number of direction determinations during the normal period of the previous day for this line. The adjustment step size is set to 0.5° each time, based on the fact that the angle error limit difference between different accuracy classes of conventional electromagnetic transformers is mostly 0.33°-0.5°.

[0052] The two adjacent switches mentioned before and after refer to two levels of switches traced upstream of the fuzzy switch, and two levels of switches traced downstream of the fuzzy switch. If the actual number of switches in a certain direction is less than two levels, for example, if the power supply bus or tie switch has been reached, the maximum number of switches actually existing in the corresponding direction shall prevail. For complex distribution network structures, this refers to the two levels of switches electrically connected upstream of the current switch and the two levels of switches electrically connected downstream, where the upstream side is the power inflow direction and the downstream side is the power outflow direction.

[0053] The execution order of the search is as follows: it is executed from near to far, that is, it starts from the adjacent switches of the previous and next levels of the fuzzy switch. If the power direction of either of the two levels of switches is clear, it will not continue to extend outward; if the power direction of both levels of switches is fuzzy, it will continue to extend outward to the second level of adjacent switches.

[0054] When the power direction of all switches within two levels before and after the fuzzy switch is fuzzy, the following implementation method is required: If the phase difference of all switches within the candidate search range is less than the set discrimination angle, that is, the power direction of all candidate switches is fuzzy, then the search range is extended outward to the third level switch until at least one switch with a clear direction is found; if it is still not found after extending to the power supply bus or tie switch, then it is determined that the power direction in that area is completely undeterminable, the current tracing is terminated and a warning is issued.

[0055] Using the power direction as a reference, find the switch with a clear power direction among all adjacent switches.

[0056] Connect all the found switches in the order they are connected to form candidate paths within the fuzzy region, and use the power direction of the first switch with a clear power direction as the reference direction for the candidate path.

[0057] The sequential connection refers to arranging the switches according to their upstream and downstream relationships in the actual power distribution network, from the end closest to the power source to the end furthest from the power source. If the candidate path is located in the downstream area of ​​the fault point, it is arranged sequentially from the side closest to the fault point to the side furthest from the fault point, so as to ensure that the direction of the candidate path is consistent with the actual electrical connection direction.

[0058] It should be noted that the power direction of the first clearly found switch is used as the overall reference direction for the candidate path. The power flow direction of the other switches with ambiguous directions within the candidate path is marked according to the reference direction, and no separate direction determination is performed.

[0059] When multiple switches with ambiguous power directions are connected in series in a candidate path, the method for determining the reference direction needs to be further clarified as follows: If multiple switches with ambiguous power directions are connected in series in a candidate path, the reference direction determined by the first switch with a clear power direction found within the search range shall be used as the unified direction of all ambiguous switches in that path segment.

[0060] If the judgment results of multiple clear switches within the search range are inconsistent, the judgment result of the clear switch closest to the fuzzy switch shall prevail.

[0061] S3. When a feeder fault occurs, trace back along the disturbance propagation path from the fault point to each power source to determine the fault point boundary switches and form a candidate set. If there is only one power source and no tie switch, isolate the upstream switch from the candidate set.

[0062] The steps for determining the boundary switches of the fault point to form a candidate set are as follows: Starting from the fault point, trace back step by step along the disturbance transmission path to each power supply direction, and select the switches that are directly electrically connected to the fault point in each tracing direction and have no other switch nodes between them as boundary switches.

[0063] The above-mentioned fault points are determined as follows: After completing the disturbance transmission path tracing, the installation position of the starting switch where the first abnormal change in electrical quantity is detected is taken as the equivalent position of the fault point; when the fault occurs on the line section between two adjacent switches, the installation position of the switch where the first abnormal change is detected is taken as the reference point of the disturbance source end.

[0064] The criteria for determining a direct electrical connection to a fault point are as follows: when moving from the fault point along the power supply path towards the power source, the first electrical device encountered is the switch node. There are only power distribution lines, including cables or overhead lines, between this switch node and the fault point, and there are no other switching devices.

[0065] The specific execution method of step-by-step tracing is as follows: if there are other switch nodes between the current switch and the fault point, then continue to advance to the next level switch.

[0066] If there are no other switch nodes between the current switch and the fault point, the current switch node is selected as the boundary switch, and tracing in that direction is stopped.

[0067] If no switching node can be traced back to a certain power supply direction, then ignore it.

[0068] The failure to trace back to any switching node in a certain power supply direction includes the following two situations: Situation 1: The fault point and the power supply are directly connected only through the power distribution line, and no switching equipment is installed in the middle of the line. For example, the fault point is located at the end of the power supply direction, and the power supply is directly connected to the location of the fault point through the line without any intermediate switch.

[0069] Scenario 2: After tracing the path in the direction of the power supply, although there is a switch node, the switch node is a marked tie switch and the tie switch is in the open state. The tracing ends at the tie switch and there is no available boundary switch in this direction.

[0070] The term "ignore" refers to the fact that the power supply direction is not included in the construction of the candidate switch set; that is, no boundary switches are selected and added to the candidate set in the power supply direction. However, this ignoring only applies to the power supply direction and does not affect the tracing and boundary switch selection in other power supply directions; each direction is processed independently.

[0071] If no switch node is found when tracing along the power supply direction, it means that the fault point is directly connected to the power supply only through the power distribution line, and no operable switch equipment is set in the middle of the line, and there is no isolation point that can perform the tripping operation.

[0072] If there are parallel branches in a certain power supply direction, then each parallel branch selects a switch that is directly electrically connected to the fault point and has no other switching nodes in between as the boundary switch.

[0073] Each of the above parallel branches should be regarded as an independent tracing path, and the same tracing steps as the main path should be performed: starting from the location of the fault point, proceed outward step by step along the independent tracing path towards the power source, and select the switch on the independent tracing path that is directly electrically connected to the fault point and has no other switch nodes in between as the boundary switch of the independent tracing path.

[0074] In a parallel branch structure, each branch is an independent electrical path and may provide short-circuit current to the fault point. If only one branch's switch is selected as the boundary switch, the fault point on other branches will still remain connected to the power supply, resulting in incomplete fault isolation. Therefore, each parallel branch must select its own boundary switch to ensure that the connection path between the fault point and each power supply is cut off.

[0075] All boundary switches selected from each power supply direction and each parallel branch are merged, and duplicate switches are removed, leaving only one to form a set of candidate switches.

[0076] Considering that in the single-source radial mode, the distribution lines are powered only by a single main grid power source, the current direction of the entire network is from the single power source to the load side. When a fault occurs, the short-circuit current upstream of the fault point flows from the power source through the upstream switch to the fault point, while there is no power source downstream of the fault point, and no short-circuit current flows through it.

[0077] Therefore, the steps for isolating the upstream switch from the candidate set if there is a single power supply and no tie switch are as follows: If the current mode is a single power supply radiation mode and there is no marked tie switch, then select the upstream switch located between the fault point and the main power grid from the candidate switch set.

[0078] The upstream switch closest to the fault point is selected as the priority isolating switch, and the remaining downstream switches are not included in the action sequence.

[0079] In single-power-source radiation mode, selecting the upstream switch closest to the fault point as the isolating switch can precisely cut off the source of the fault current with a single switch operation, while limiting the power outage area to the smallest area where the fault point is located.

[0080] S4. Verify the combination of the selected set and select the combination with the lowest overall cost. The main grid side and the distributed power supply side shall execute simultaneously according to the principle of coordinated circuit breaking. The selected combination shall disconnect the fault point from all power supply paths. The non-faulty area shall rely on the marked tie switch to restore power supply to obtain the action sequence and send it out for execution.

[0081] In power distribution network fault isolation, the fewer switches that are disconnected, the smaller the power outage area and the lower the losses, and the lower the execution risk caused by switch failure or communication failure.

[0082] Therefore, the above-mentioned steps for selecting the combination with the minimum overall cost are as follows: enumerate all possible switch combinations from the set of candidate switches, with each combination containing at least one switch; enumerate in order of increasing number of switches in the combination, and perform isolation integrity verification on each combination during the enumeration process; when a combination that satisfies the isolation integrity condition is obtained for the first time, the enumeration is stopped and the combination is determined as the combination with the minimum overall cost; where the overall cost refers to the number of switch actions required to perform the tripping operation in order to achieve fault isolation.

[0083] If the set of available switches is empty, it is determined that there are no available disconnect switches. A trip command is sent to the upper-level backup protection and the system waits for a response from the upper-level switch. If the upper-level switch action times out, the system continues to send a trip command to the next higher level.

[0084] After all switches in each combination are simultaneously disconnected, check whether there is an electrical path connecting the fault point to each power source.

[0085] The specific execution method of the verification is as follows: For each combination to be verified, the distribution control station takes the disconnected switch in the combination as the blocking node and the remaining closed switches as the path node, and performs the verification step by step downstream from the main power grid power source and distributed power source side along the closed switches to determine whether the location of the fault point can be reached.

[0086] "A connected electrical path" means that all switches along the path from the power source to the fault point are closed, and there are no open or disconnected switches.

[0087] If, after disconnecting all selected switches in a combination, there is still an electrical path connecting the fault point to any power supply, then the isolation integrity condition is not met and the combination is discarded.

[0088] The criteria for determining the isolation integrity condition are as follows: If a search path in a certain power supply direction can reach the fault point, it is determined that after disconnecting the selected switch, there is still a connected electrical path between the fault point and the power supply, and therefore the isolation integrity condition is not met and the fault is eliminated. If the search in all power supply directions cannot reach the fault point, then the isolation integrity condition is met.

[0089] Sort the remaining switch combinations in ascending order of the total number of activated switches, and select the switch combination with the fewest activated switches as the combination with the lowest overall cost.

[0090] Since disconnecting an additional switch means expanding the power outage area, increasing the switching operation loss, and incurring an additional risk of execution failure, minimizing the total number of operating switches is the preferred criterion, which can minimize operational costs while ensuring isolation effectiveness.

[0091] The above-mentioned main grid side and distributed power generation side shall simultaneously perform the following steps according to the principle of coordinated circuit breaking: identify the connection direction of each switch in the set of candidate switches, mark the switch connected to the distributed power generation as the distributed power generation side switch, and mark the switch connected to the main grid as the main grid side switch.

[0092] Specifically, the power supply type connected to each side of the switch is determined as follows: if a port on a certain side can be traced back to the substation bus or the main power grid through the closed switch path, it is determined to be the main power grid side.

[0093] If a port on one side can be traced back to a distributed power source, including photovoltaic, energy storage, and wind power generation, through a closed switch path, then it is determined to be the distributed power source side.

[0094] If a port on one side can be traced to both the main grid power source and the distributed power source, the power type with the fewest switches will be used as the determination result.

[0095] If both ports trace back to the same type of power source, the switch is not marked as either a distributed power source side switch or a main grid side switch.

[0096] If both sides of a switch are traceable to distributed generation sources, the switch is marked as a distributed generation-side switch; if both sides of a switch are traceable to main grid power sources, the switch is marked as a main grid-side switch. If the connection direction of a switch cannot be determined due to communication interruption or missing topology data, the switch is marked as a main grid-side switch by default, thus prioritizing the power supply security of the main grid.

[0097] In the selected combination, the distributed power source side switch and the main grid side switch shall be opened in the same sequence, and the opening delay of the distributed power source side shall not exceed the delay range of the main grid side.

[0098] The same timing execution means that the distributed power supply side switches and the main grid side switches in the selected combination are all included in the same action sequence, and the tripping command is issued in sequence according to the order in the action sequence. After receiving the command, each switch performs its own tripping operation.

[0099] Distributed power source (DPS) side tripping delay refers to the time interval from the moment the main grid side switch receives the tripping command to the moment the DPS side switch actually completes the tripping operation. Since the DPS continues to inject short-circuit current into the fault point after a fault occurs, if the DPS side switch trips too late, the DPS side switch may disconnect first, allowing the DPS to supply power to the fault point independently, thus prolonging the duration of the fault current.

[0100] The preset range on the main grid side is determined as follows: The lower limit of the preset range on the main grid side is obtained by acquiring the inherent tripping action time of the switch through the switch's technical parameters, and the round-trip delay between the distribution control master station and the switch is obtained from the maximum value of the actual network test. This is set as the sum of the inherent action time of the switch and the round-trip delay of the communication. This ensures that the switch has sufficient time from receiving the command to actually completing the tripping action, avoiding failure to operate due to insufficient time. The upper limit is obtained by directly reading the action delay of the upper-level backup protection device from the factory technical parameters of the protection device, and subtracting the lower limit of the preset range on the main grid side. This represents the latest allowed completion time of the tripping action at this level. This ensures that the tripping action at this level is completed before the action of the upper-level protection, meeting the protection selectivity requirements and preventing cascading tripping from expanding the power outage range. If the calculated lower limit is greater than the upper limit, the switch is determined not to meet the coordination conditions and is removed from the list.

[0101] Distributed power supply side switches are prohibited from performing tripping operations before the main grid side switches.

[0102] The short-circuit current supplied by the main power grid is much greater than that of distributed generation. If the distributed generation side switch trips prematurely, the main power grid will continue to inject short-circuit current into the fault point, failing to achieve the isolation objective and instead prolonging the duration of the fault current's impact on equipment and the system. Therefore, the distributed generation side switch must not trip prematurely on its own; it must be executed in a coordinated sequence with the main grid side switch to ensure that the main power grid path is disconnected first.

[0103] The steps for restoring power to the non-faulty area using the marked tie switches are as follows: After the fault point is disconnected from all power supply paths, read the positions of all marked tie switches.

[0104] The reading operation is performed after confirming that the connection path between the fault point and all power sources has been cut off. If the fault isolation operation fails, the step of reading the position of the interconnection switch is skipped, and the alarm and upper-level backup protection process is initiated directly.

[0105] Sections located downstream of the fault point and without a disconnected isolation boundary switch between them, as well as sections located on the side of the disconnected isolation boundary switch away from the fault point, are identified as non-fault sections.

[0106] After the isolating boundary switch opens, it divides the original electrical network into two sides: one side is closer to the power source, and the other side is closer to the fault point. The entire area on the power source side is not faulty, but it loses power due to the boundary switch opening; this is a non-faulty section and needs to be restored. The area on the fault point side includes the fault point itself and cannot be restored as a whole. However, the portion downstream of the fault point does not contain the fault point itself, but is isolated only because it shares the same connectivity with the fault point; this is also a non-faulty section and needs to be restored.

[0107] Therefore, the section located downstream of the fault point and without a disconnected isolating boundary switch between them describes the portion of the connected domain containing the fault point that is far from the power source and does not include the fault point. The section located on the side of the disconnected isolating boundary switch that is far from the fault point describes the entire area on the power source side of the boundary switch. Neither part contains the fault point, so both are identified as non-faulty sections. The reason for this judgment is to use the isolating boundary switch as the boundary to restore power to all de-energized areas that do not contain the fault point.

[0108] Interconnecting switches located in non-faulty sections and in the open state are identified as interconnecting switches that can be restored to power supply.

[0109] The power supply path corresponding to the identified tie switch is matched with the main grid power source that is still energized. If the tie switch can be connected to the main grid power source through a certain power supply path, the corresponding tie switch is included in the restoration closing sequence. If there is no energized main grid power source, it is abandoned and waits.

[0110] The path matching determination method is as follows: the power type connected to the end of the power supply path of the tie switch is compared with the main grid power supply that is still energized. If the end of the power supply path is a substation busbar or a main grid power supply outgoing switch, and the main grid power supply is still energized in the current state, then it is determined that the tie switch can connect to the main grid power supply. If multiple power supply paths are connected to the same main grid power supply, they are matched only once and not included repeatedly.

[0111] If an already tripped isolation boundary switch is encountered during the tracing process, the tracing in that direction will be terminated. The power supply path in that direction will not participate in the matching because the isolation boundary switch has been opened. Although the side away from the fault point is energized, it cannot cross the isolation boundary to supply power to the non-fault section.

[0112] If all main grid power sources are currently out of power and there is no available energized power source, then the generation of the current restoration closing sequence will be abandoned, and the tie switch will remain in the open state while waiting for the main grid power source to be restored. During the waiting period, the distribution control station will check whether the main grid power source has been restored according to the detection cycle. Once any main grid power source is detected to be energized, the path matching step will be re-executed and a restoration closing sequence will be generated.

[0113] The restoration closing sequence is sent to the corresponding tie switch to perform the closing operation, so that the load in the non-faulty section can regain power.

[0114] S5. After execution, send back confirmation. If the timeout is not fully successful, jump to the upper-level backup and issue a warning. If successful, re-identify the path and accumulate the number of iterations. If the same fault point occurs repeatedly, block reclosing and trigger a dead zone warning.

[0115] See Figure 3As shown, specifically, after the action sequence is issued, a timer is started to wait for confirmation signals from each switch. If all confirmation signals are received within a limited time, the execution is considered successful. The disturbance transmission path is re-identified based on the new measurement data, and the number of iterations is accumulated.

[0116] The feedback confirmation signal refers to the operation result feedback signal sent by the control unit built into each smart switch to the power distribution control station through the communication network after each smart switch has completed the opening or closing operation.

[0117] The specific steps for re-identifying the disturbance transmission path based on the new measurement data are as follows: After successful execution, the power distribution control master station re-acquires the electrical measurement data of each smart switch at the current moment. Based on the switch status and measurement data after this successful execution, the disturbance transmission path under the current operating condition is re-identified according to the steps for tracing the disturbance transmission path. The re-identification result is compared with the previous identification result to determine whether the disturbance has been completely eliminated. At the same time, the successful execution is counted in the iteration count, and the iteration count is incremented by one.

[0118] If any switch fails to return a signal within the specified time, or fails to return a signal, the execution is deemed to have timed out, and a trip command is sent to the upper-level backup protection system along with a warning.

[0119] Specifically, a trip command is sent to the upper-level backup protection device via a communication network. The upper-level backup protection device refers to the protection device located one level above the feeder where the fault point is located, i.e., on the power supply side, such as the protection device corresponding to the substation's output circuit breaker or the distribution terminal corresponding to the upstream feeder switch. The trip command must include at least the equipment number of the upper-level backup protection device, the trip target switch number, and the action indicator.

[0120] Warning messages are sent to the human-machine interface of the power distribution control master station for operation and maintenance personnel to view in real time, and are also recorded in the event log of the master station.

[0121] The time limit is determined by recording the time difference between issuing an action command and receiving a confirmation signal. The maximum value of this time difference from all historical successful operation records on the same line is taken as the time limit. The maximum value of the time difference represents the actual boundary of the operation response time under normal operating conditions of the line in history, ensuring that all historical normal operations are not judged as timeouts.

[0122] If the path is identified again after each re-identification and the result is the same as the previous identification, the isolation scheme will not be executed again.

[0123] If the same fault point is still identified after the count reaches the maximum number of iterations, and the fault characteristics are consistent with the previous one, the reclosing function of the corresponding line will be blocked and a permanent fault warning will be triggered.

[0124] The phrase "the same fault point is still identified" means that after the current re-identification of the disturbance transmission path, the location of the fault point is the same as the location of the fault point in the previous identification result, that is, the end node of the disturbance transmission path identified in the two identifications is the same smart switch or the same line section. If the node number corresponding to the fault point identified in the current identification is consistent with the previous recorded value, it is determined that the same fault point is still identified.

[0125] The fault characteristics are consistent with the previous one, which means that during the current re-identification process, the abnormal electrical quantity characteristic parameters detected at the fault point are the same as the characteristic parameters recorded in the previous one, and the voltage drop directions on both sides of the fault point are the same.

[0126] The maximum number of iterations is determined as follows: Historical fault records for the line over the past three years are obtained, the number of transient faults and permanent faults are counted, and the proportion of transient faults to all faults is calculated. The maximum number of iterations is set as follows: 4 iterations when the proportion exceeds 70%; 3 iterations when the proportion is between 50% and 70%; 2 iterations when the proportion of transient faults is less than 50%. For newly built lines or lines without historical fault statistics, the default maximum number of iterations is 3. After one year of operation and accumulation of sufficient historical data, the number of iterations will be dynamically adjusted according to the above rules.

[0127] The basis for setting these rules is as follows: the higher the proportion of transient faults, the more temporary the line faults are, requiring more iterations to confirm whether they are permanent faults, thus avoiding unnecessary outages caused by misjudging transient faults as permanent faults; the higher the proportion of permanent faults, the fewer iterations should be used to shorten the time and number of repeated impacts under permanent faults.

[0128] Once the fault point is successfully isolated and power is restored to the non-faulty area, the iteration count will be reset to zero.

[0129] The power distribution control master station establishes an independent iteration counter for each fault. The iteration counter is used to accumulate the number of times the same fault point is repeatedly identified to prevent repeated overlap from impacting the system. Once the fault point is successfully isolated and power is restored to the non-fault area, it means that the current fault event has been completely processed. The historical accumulated value of the iteration counter corresponding to the fault point is no longer of reference significance for subsequent new faults.

[0130] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0131] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0132] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0133] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0134] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A remote power distribution control method for intelligent switches based on measurement data, characterized in that: include: Acquire electrical measurement data from each smart switch, and when abnormal sudden changes in electrical quantities are detected, identify the power supply mode based on the switch status and mark the interconnecting switch. The disturbance propagation path is traced based on the power direction and power supply mode, and the location of the tie switch is used as the tracing boundary. When the power direction is ambiguous, the search range is expanded to the two adjacent switches. When a feeder fault occurs, the fault point is traced back along the disturbance propagation path to each power source to determine the fault point boundary switches and form a candidate set. If there is a single power source and no tie switch, the upstream switch is isolated from the candidate set. For the selection of sets and combinations, the combination with the lowest overall cost is selected. The main grid side and the distributed power supply side are executed simultaneously according to the principle of coordinated circuit breaking. The selected combination needs to disconnect the fault point from all power supply paths. The non-faulty area relies on the marked tie switch to restore power supply to obtain the action sequence and send it out for execution. After execution, a confirmation is sent back. If the operation is not fully successful within a timeout period, the system will jump to the upstream backup and issue a warning. If the operation is successful, the path will be re-identified and the number of iterations will be accumulated. If the same fault point occurs repeatedly, the reclosing will be blocked and a dead zone warning will be triggered.

2. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The method of identifying the power supply mode and marking the interconnection switch based on the switch status includes: Read the opening and closing status of each smart switch. Switches in the closed state are recorded as closed nodes, and switches in the open state are recorded as open nodes. Starting from the main power grid power source side, query each power supply path. If only one main power grid power source reaches all loads, it is a single power source radiation mode. If two or more main power grid power sources reach the loads, it is a multi-power source power supply mode. When a switch is in an open state and its two sides are connected to different power supplies, it is marked as a tie switch.

3. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The tracking disturbance propagation path includes: The switch that detects an abnormal change in electrical quantity is used as the starting switch. The phase difference between the voltage and current at the starting switch is read. If the phase difference is within the lag range, the power flows in the forward direction. If it is within the leading range, the power flows in the reverse direction. The side to which power flows into the current switch is marked as the upstream side, and the side to which power flows out of the current switch is marked as the downstream side. The switch electrically connected to the upstream side of the current switch is marked as the upstream switch, and the switch electrically connected to the downstream side is marked as the downstream switch. Starting from the starting switch, trace along the power direction. After determining the power direction at each switch, continue forward until reaching the power supply side or the tie switch position. Connect the switches in sequence to generate a disturbance transmission path.

4. The intelligent switch remote power distribution control method based on measurement data according to claim 3, characterized in that: The step of expanding the search range to two adjacent switch stages when the power direction is ambiguous includes: When the absolute value of the phase difference between the starting switches is less than the set discrimination angle, the power direction is determined to be ambiguous, and the two adjacent switches before and after are included in the search. Using the power direction as a reference, locate the switch with a clear power direction among adjacent switches; Connect all the found switches in the order they are connected to form candidate paths within the fuzzy region, and use the power direction of the first switch with a clear power direction as the reference direction for the candidate path.

5. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The candidate set of switches for determining the fault point boundary includes: Starting from the fault point, trace the disturbance propagation path step by step towards each power supply direction, and select the switches that are directly electrically connected to the fault point in each tracing direction and have no other switch nodes between them as boundary switches. If no switching node can be traced back to a certain power supply direction, then ignore it; If there are parallel branches in a certain power supply direction, each parallel branch shall select a switch that is directly electrically connected to the fault point and has no other switch nodes in between as the boundary switch. All boundary switches selected from each power supply direction and each parallel branch are merged, and duplicate switches are removed, leaving only one to form a set of candidate switches.

6. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The provision that if there is a single power supply and no tie switch, the upstream switch is isolated from the candidate set includes: If the current mode is a single-power-source radiation mode and there is no marked tie switch, then select the upstream switch located between the fault point and the main power grid from the set of candidate switches. The upstream switch closest to the fault point is selected as the priority isolating switch, and the remaining downstream switches are not included in the action sequence.

7. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The selection of the combination with the minimum overall cost includes: From the set of candidate switches, enumerate the combinations that contain at least one switch in order of the number of switches in the combination from least to most. If the set of candidate switches is empty, it is determined that there are no available disconnect switches, a trip command is sent to the upper-level backup protection, and the system waits for the upper-level switch to take action. If the upper-level switch takes action and times out, the system continues to send a trip command to the next higher level. After all switches in each combination are simultaneously disconnected, check one by one whether there is an electrical path connecting the fault point to each power source. If, after disconnecting all selected switches in a combination, there is still a connected electrical path between the fault point and any power supply, then the isolation integrity condition is not met and the combination is discarded. Sort the remaining switch combinations in ascending order of the total number of activated switches, and select the switch combination with the fewest activated switches as the combination with the lowest overall cost.

8. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The simultaneous execution of the main grid side and the distributed power supply side according to the principle of coordinated circuit breaker operation includes: Identify the connection direction of each switch in the set of candidate switches, mark the switches connected to the distributed power source as distributed power source side switches, and mark the switches connected to the main power grid as main grid side switches. In the selected combination, the distributed power source side switch and the main grid side switch shall be opened in the same sequence, and the opening delay of the distributed power source side shall not exceed the delay range of the main grid side. Distributed power supply side switches are prohibited from performing tripping operations before the main grid side switches.

9. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: The restoration of power supply to the non-faulty area via the marked interconnection switch includes: After the fault point is disconnected from all power supply paths, read the positions of all marked interconnection switches; Sections located downstream of the fault point and without a disconnected isolation boundary switch between them, as well as sections located on the side of the disconnected isolation boundary switch away from the fault point, are identified as non-fault sections. Identify the tie switch located in the non-faulty section and in the open state as a tie switch that can be restored to power supply. The power supply path corresponding to the identified tie switch is matched with the main power grid power source that is still energized. If the tie switch can be connected to the main power grid power source through a certain power supply path, the corresponding tie switch is included in the restoration closing sequence. If there is no energized main power grid power source, it is abandoned and waits. The restoration closing sequence is sent to the corresponding tie switch to perform the closing operation, so that the load in the non-faulty section can regain power.

10. The intelligent switch remote power distribution control method based on measurement data according to claim 1, characterized in that: After execution, confirmation is sent back. If the process fails to complete successfully within a timeout period, the system jumps to the upstream backup and issues a warning. If successful, the path is re-identified and the number of iterations is accumulated. If the same fault point recurs, reclosing is blocked and a dead-zone warning is triggered, including: After issuing the action sequence, start the timer and wait for confirmation signals from each switch. If all confirmation signals are returned within the time limit, the execution is considered successful. The disturbance transmission path is re-identified based on the new measurement data and the number of iterations is accumulated. If there are switches that fail to return data or fail to return data within the specified time, the execution is deemed to have timed out, and a trip command is sent to the upper-level backup protection and a warning is issued. If the current path identification result is the same as the previous one after each re-identification, the isolation scheme will not be executed again. If the same fault point is still identified after the count reaches the maximum number of iterations, and the fault characteristics are consistent with the previous one, then the reclosing function of the corresponding line will be blocked and a permanent fault warning will be triggered. Once the fault point is successfully isolated and power is restored to the non-faulty area, the iteration count will be reset to zero.

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