Power distribution network power supply recovery method and system considering cooperation of multiple types of distributed power supplies

Abstract

The invention discloses a power distribution network power supply recovery method and system considering multi-type distributed power supply cooperation, and the method comprises the steps: enabling a fault section to be successfully isolated, and carrying out the non-voltage switching-on of a network-following type DG in an intertripping power-losing region; constructing a source-load balance island based on the network construction type DG, and preferentially recovering an important load; when there is no contact, the upstream switch of the fault point carries out non-voltage reclosing to process an instantaneous fault, and island grid connection is planned; when connection exists, an optimal connection switch is optimized according to the capacity of a connection line and the capacity of a power-losing load, closing is carried out after an unrecoverable section is cut off, and staged power restoration is achieved by circularly cutting off the unrecoverable load, grid connection of the grid-following type DG and updating the recoverable capacity by considering the capacity of the adjacent grid-following type DG. And when an island adjacent section is recovered, the connected switches are subjected to synchronization grid connection. According to the invention, through a multi-type DG cooperative control strategy, the maximum capacity safety recovery of a non-fault section load is realized, the active support capability of the DG is fully exerted, and the reliability of the power distribution system is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of medium-voltage distribution network power supply restoration, and particularly relates to a method and system for power supply restoration of a distribution network considering the coordination of multiple types of distributed power sources. Background Art

[0002] With the large-scale access of DG (Distributed Generator) to the distribution network, the existing fault power supply restoration methods usually adopt the strategy of actively cutting off DG. The traditional single-path restoration scheme has limitations and fails to fully utilize the supporting role of DG, and cannot achieve the coordinated optimization of multiple objectives for power supply restoration.

[0003] In the prior art, although CN119482659A and CN119209521A involve island division and transient optimization, they have the following technical defects: (1) The traditional centralized control depends on the global optimization of the master station, resulting in high communication delay and poor real-time performance; (2) The existing DG fault ride-through coordination mechanism is imperfect. For example, the dynamic characteristics of DG low-voltage ride-through are not fully considered in the impact on the restoration strategy, resulting in a sharp drop in the system support capacity after cutting off DG; (3) The liaison path selection strategy is single. For example, the analysis of DG output fluctuation and line capacity margin is lacking, which may cause overload. Summary of the Invention

[0004] To solve the deficiencies in the prior art, the present invention provides a method and system for power supply restoration of a distribution network considering the coordination of multiple types of distributed power sources, solves the problems proposed in the above background art, fully utilizes the supporting role of DG, realizes the coordinated optimization of multiple objectives for power supply restoration, improves the reliability of the distribution system, and is applicable to the medium-voltage distribution network system.

[0005] The present invention adopts the following technical solutions.

[0006] The first aspect of the present invention provides a method for power supply restoration of a distribution network considering the coordination of multiple types of distributed power sources, including: Obtain the signal of successful isolation of the fault section and determine the power outage area; Cut off all grid-connected distributed power sources connected to the node that receives the isolation success signal in the power outage area; When the power outage area contains network-forming distributed power source nodes, construct a planned island, determine the power supply restoration order of loads in each planned island according to the load level, and preferentially restore the smallest restoration unit with the highest load level; When there is no connection between the power outage area and other areas of the distribution network, detect the status of the no-voltage reclosing of the switch upstream of the fault point, and determine the power supply restoration strategy according to the fault type and the status of the no-voltage reclosing; When there is a connection between the power outage area and other areas of the distribution network, determine the optimal connection switch according to the power of the connection line and the power outage load. After cutting off the non-recoverable section, close the optimal connection switch. Based on the capacity of adjacent grid-connected distributed power sources, realize staged power restoration by cyclically cutting off non-recoverable loads, connecting grid-connected distributed power sources to the grid, and updating the recoverable capacity until there is no non-recoverable section; When restoring to the section adjacent to the island, the switch connecting the island area and the area where the connection switch is closed for restoration checks synchronization and is connected to the grid, and supplies power to the remaining loads in the island according to the load power supply restoration sequence and the updated recoverable capacity.

[0007] Optionally, the planned island includes multiple minimum restoration units. Determine the load power supply restoration sequence within each planned island according to the load level, including: Calculate the load power of each minimum restoration unit; When the load is greater than or equal to the load power of the minimum restoration unit, determine the load power supply restoration sequence according to the total load power supply capacity, load level, and corresponding constraint conditions of different loads within the preset time period.

[0008] Optionally, the constraint condition for the total load power supply capacity of the load within the preset time period is that the total load power supply capacity of the load within the preset time period is less than the capacity of the network-forming distributed power source. Determine the load power supply restoration sequence according to the total load power supply capacity, load level, and corresponding constraint conditions of different loads within the preset time period, including: Divide the loads according to the sum of the capacities of the network-forming distributed power sources and the constraint condition of the total load power supply capacity of the load within the preset time period to obtain multiple load sets; Determine the load power supply sequence according to the load level in multiple load sets, and allocate the recoverable load capacity according to the load level.

[0009] Optionally, the power supply restoration strategy includes instantaneous faults and permanent faults.

[0010] Optionally, determining the optimal connection switch according to the connection line and the power of the power outage load includes: Calculate the recoverable capacity after the grid-connected distributed power source connected to the island is connected to the grid; Calculate the maximum transfer power of each connection line before power restoration; Calculate the maximum recovery ability of the maximum transfer power of each connection line according to the recoverable capacity and the maximum transfer power of each connection line before power restoration, and determine the optimal connection switch according to the maximum recovery ability of the maximum transfer power of each connection line.

[0011] Optionally, calculating the maximum recovery ability of the maximum transfer power of each connection line according to the recoverable capacity and the maximum transfer power of each connection line before power restoration, and determining the optimal connection switch according to the maximum recovery ability of the maximum transfer power of each connection line includes: Sum the recoverable capacity and the maximum transfer power of each tie line before power restoration to obtain the maximum recovery capacity of the maximum transfer power of each tie line; Select the tie line corresponding to the maximum value among the maximum recovery capacities as the optimal tie switch.

[0012] Optionally, after the grid-connected distributed power sources are connected to the grid and the recoverable capacity is updated, the method further includes: Update the sum of the power of the power-off loads in the non-faulty section, and determine whether to conduct staged power restoration according to the updated sum of the power of the power-off loads in the non-faulty section and the updated recoverable capacity.

[0013] Optionally, update the recoverable capacity according to the following formula: , In the formula, is the recoverable capacity, is the set of sections that have been restored power supply, is the maximum transfer power of tie line n, is the active power before the fault of the grid-connected distributed power source in the non-faulty power-off section connected to the island area, is the proportion of the active power before the fault that can be output within a preset time period when the voltage at the point of common coupling reaches the normal operation area.

[0014] Optionally, the method further includes: Judge whether there is a recoverable section based on the power supply recovery capacity constraint condition, where the power supply recovery capacity constraint condition is that the load capacity within a preset time period is less than or equal to the maximum transfer power of the tie line.

[0015] The second aspect of the present invention provides a power distribution network power supply recovery system considering the coordination of multiple types of distributed power sources. The system includes: A determination module, configured to obtain a signal indicating successful isolation of the fault section and determine the power-off area; A disconnection module, configured to disconnect all grid-connected distributed power sources connected to the node that receives the isolation success signal in the power-off area; A construction module, configured to construct a planned island when the power-off area includes a network-forming distributed power source node, determine the power supply recovery order of loads in each planned island according to the load level, and preferentially restore the smallest recovery unit with the highest load level; A first recovery module, configured to detect the status of the no-voltage reclosing of the switch upstream of the fault point when the power-off area has no connection with other areas of the power distribution network, and determine the power supply recovery strategy according to the type of fault and the status of the no-voltage reclosing; The second recovery module is used to, when there is a connection between the power outage area and other areas of the distribution network, determine the optimal connection switch according to the connection line and the power of the power outage load, close the optimal connection switch after cutting off the irrecoverable section, and based on the capacity of adjacent grid-connected distributed power sources, realize staged power restoration by cyclically cutting off irrecoverable loads, connecting grid-connected distributed power sources to the grid, and updating the recoverable capacity until there is no irrecoverable section; The third recovery module is used to, when recovering to the section adjacent to the island, check the synchronization and connect to the grid for the switch connecting the island area and the area where the connection switch is closed for power restoration, and supply power to the remaining loads in the island according to the load power supply restoration sequence and the updated recoverable capacity.

[0016] A third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, the power supply restoration method for a distribution network considering the coordination of multiple types of distributed power sources is implemented.

[0017] A fourth aspect of the present invention provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the power supply restoration method for a distribution network considering the coordination of multiple types of distributed power sources is implemented.

[0018] Compared with the prior art, the beneficial effects of the present invention at least include: The present invention proposes a power supply restoration method for a distribution network considering the coordination of multiple types of distributed power sources. By deploying intelligent self-healing terminals at important nodes, constructing a horizontal peer-to-peer communication network, adopting a "distributed control + multi-stage coordination" architecture, adaptively selecting the optimal path based on the capacity margin index of the connection line, and realizing real-time topology recognition and dynamic correction of the capacity margin between intelligent self-healing terminals through a short-delay channel, multi-stage and maximum-range power supply restoration are achieved. The present invention can achieve the safe restoration of the maximum capacity of loads in non-fault sections, give full play to the supporting role of different types of DGs in the power supply restoration process, and significantly improve the reliability of the distribution system.

[0019] The present invention first proposes a method for adaptively selecting the optimal power transfer path based on the capacity margin index of the connection line, which solves the problems of insufficient adaptability of traditional single fixed power transfer and limited load restoration.

[0020] The present invention first proposes a method for dynamically updating the recoverable capacity margin based on the rapid interaction between terminal information, realizing multi-stage and maximum-range power supply restoration.

[0021] The present invention proposes a priority power supply restoration strategy for important-level loads based on the active construction of an island by network-forming DGs, improving the level of in-situ and nearby consumption of new energy and the continuous power supply ability of important loads.

[0022] The present invention proposes a power supply restoration method considering the supporting effects of different types of DGs, which realizes the maximum-capacity and safe restoration of the loads in the non-fault sections and significantly improves the reliability of the distribution system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them: Figure 1 FIG. is a schematic flow chart of a power supply restoration method considering the coordination of multiple types of distributed power sources provided for the specific implementation manner of the present invention; Figure 2 FIG. is an explanatory diagram of the division of the minimum restoration unit provided for the specific implementation manner of the present invention; Figure 3 FIG. is an implementation diagram of a typical multi-connected grid provided for the specific implementation manner of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Now, the exemplary embodiments of the present invention will be introduced with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not limitations on the present invention. In the drawings, the same unit / element uses the same reference numeral.

[0025] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood to have a meaning consistent with the context of their related fields and should not be understood as idealized or overly formal meanings.

[0026] As Figure 1 shown, Embodiment 1 of the present invention provides a power supply restoration method considering the coordination of multiple types of distributed power sources, which is applicable to the medium-voltage distribution network system and realizes the fast, safe and orderly power supply restoration in place for the non-fault sections. Specifically, it includes the following steps: Step 1: Obtain the signal of successful isolation of the fault section and determine the power outage area.

[0027] Preferably, the power outage area due to the fault includes: Based on the information interaction between nodes, the first-node switch at the power source side and the load side of the fault point trips to isolate the fault section, and the area composed of the tripped nodes on the load side to the end nodes is the power outage area.

[0028] As shown in Table 1, the nodes include load nodes, DG nodes, and tie nodes. Among them, the load nodes are divided into first-level, second-level, and third-level according to the load level, and the DG nodes are divided into grid-connected type and network-forming type according to the type.

[0029] Table 1

[0030] In Table 1, 0 indicates that the node is not the corresponding level load, and 1 indicates that the node is the corresponding level load.

[0031] Step 2: Cut off all grid-connected distributed power sources connected to the nodes that receive the isolation success signal in the power outage area.

[0032] By tripping the grid-connected DG in the power outage area, the conditions for no-voltage reclosing or tie closing are met.

[0033] Specifically, when the node information is a grid-connected DG node, after receiving the fault section isolation success signal, the switch operates to cut off the connected grid-connected DG, meeting the conditions for no-voltage reclosing or tie closing.

[0034] No-voltage reclosing means that when the line fails and trips, if it is detected that the line has no voltage, it is considered that the fault has been eliminated, and the reclosing device will issue a closing command to attempt to restore power supply.

[0035] Tie closing realizes the connection and power supply restoration between power supply systems through tie switches. When one of the systems fails or loses power, by closing the tie switch, the other system supplies power to the power outage area.

[0036] The condition for no-voltage reclosing or tie closing is that there is voltage on the single side of the system power source side. If the grid-connected DG does not disconnect from the grid, it will cause voltage on both sides and does not meet the conditions for no-voltage reclosing or tie closing.

[0037] Step 3: When the power outage area contains network-forming DG nodes, construct a planned island, determine the load power supply restoration order according to the load level in each planned island, and preferentially restore the smallest restoration unit with the highest load level.

[0038] In this embodiment, by constructing a planned island based on the source-load balance condition, the continuous power supply of important loads can be ensured and the power outage time can be reduced.

[0039] Preferably, constructing a planned island based on the source-load balance condition and determining the load power supply restoration order in each planned island includes: Step 3.1: When the power outage area contains network-forming DG nodes, construct a planned island based on the source-load balance condition and determine the load power of each smallest restoration unit:

[0040] In the formula, is the load power of the i-th smallest restoration unit, is the power of the upstream boundary switch of the smallest restoration unit, m is the number of sectionalizing switches within the smallest restoration unit, and t is the section time during normal operation before the fault occurs. is the sum of the powers of each downstream boundary switch of the smallest restoration unit, is the DG injection power in the section where the smallest restoration unit is located.

[0041] The load power of the smallest restoration unit is the total load that the smallest restoration unit can support.

[0042] As Figure 2 shown, Figure 2 is the explanatory diagram for the division of the smallest restoration unit. The smallest restoration unit is the area formed by the main line sectionalizing switch and the branch / sectionalizing switch, and the branch switch and the sectionalizing switch, and does not contain other switches with three-remote functions inside.

[0043] Figure 2 In , the substation outgoing line switch CB and the main line sectionalizing switch FD1, the main line sectionalizing switch FD1 and the main line sectionalizing switch FD2, the branch switch FS1, the branch switch FS1 and the sectionalizing switch YS1, the main line sectionalizing switch FD2 and the main line sectionalizing switch FD3, the branch switch FS2, the branch switch FS2 and the sectionalizing switch YS2, the tie switch LSW1, the main line sectionalizing switch FD3 and the main line sectionalizing switch FS4, the main line sectionalizing switch FS4 and the branch switch FS3, the tie switch LSW2, and the branch switch FS3 and the sectionalizing switch YS3 respectively form the smallest restoration unit.

[0044] Combined with Figure 2 shown, the load power of the smallest restoration unit 1 is:

[0045] In the formula, is the power of the upstream switch CB of the smallest restoration unit 1, is the sum of the powers of the downstream main line sectionalizing switches. As Figure 2 can be seen, there is no DG in this smallest restoration unit, so the DG injection power is 0.

[0046] The load power of the smallest restoration unit 7 is:

[0047] In the formula, is the power of the upstream switch FS2 of the smallest restoration unit 7, is the sum of the powers of the sectional switches on the downstream main line, is the injected power of the DG in the section where the minimum restoration unit 7 is located.

[0048] Step 3.2: When the load is greater than or equal to the load power of the minimum restoration unit, determine the load power supply restoration sequence according to the total power supply load capacity, load level, and corresponding constraint conditions of different loads in the preset time period. Step 3.2 specifically includes: Step 3.2.1: The constraint condition for the total power supply load capacity of the load in the preset time period is that the total power supply load capacity of the load in the preset time period is less than the capacity of the network-forming DG. When the load is greater than or equal to the load power of the minimum restoration unit, determine the first index value of the load according to the constraint condition of the total power supply load capacity of the load in the preset time period.

[0049] The power supply to the load with the total power supply load capacity less than the capacity of the network-forming DG should be restored first, and the constraint condition is:

[0050] In the formula, is the sum of the capacities of the network-forming DGs at time t, is the load capacity at time t.

[0051] Specifically, when the total power supply load capacity of the load in the preset time period is less than the capacity of the network-forming DG, the first index value can be set to 3, otherwise the first index value is set to 0.

[0052] Step 3.2.2: Determine the second index value of the load according to the load level and its corresponding constraint conditions.

[0053] Specifically, the load levels include primary load, secondary load, and tertiary load.

[0054] The primary load should be restored first and needs to meet:

[0055] Among them, is the priority restoration capacity of the primary load, is the proportion coefficient of the primary load capacity, is greater than or equal to 60%, is the load capacity at time t.

[0056] The secondary load is restored secondarily, and the remaining capacity allocation needs to meet: (4) Among them, is the secondary priority restoration capacity of the secondary load, is the proportion coefficient of the secondary load capacity, is greater than or equal to 60%, is the load capacity at time t.

[0057] For the dynamic restoration of tertiary loads, the remaining capacity allocation needs to satisfy: (5) Among them, is the dynamic restoration capacity of tertiary loads.

[0058] Specifically, when the restoration capacity of primary loads is less than or equal to the proportion of primary load capacity in the total power supply load capacity, set the second index value to 3, otherwise 0; when the restoration capacity of secondary loads is less than or equal to the proportion of secondary load capacity in the total power supply load capacity, set the second index to 2, otherwise 0; when the restoration capacity of tertiary loads is less than or equal to the proportion of tertiary load capacity in the total power supply load capacity, set the second index to 1, otherwise 0. Among them, the sum of the proportion of tertiary load capacity, the proportion of primary load capacity and the proportion of secondary load capacity is 1.

[0059] Step 3.2.3: Determine the load power supply restoration order according to the first index value and the second index value of the load.

[0060] Specifically, perform a summation calculation according to the first index value, the second index value of the load and their corresponding weights, and determine the load power supply restoration order according to the calculation result. The larger the calculation result, the more priority is given to restoring the load power supply.

[0061] Specifically, multiply the first index value and the second index value of the load, and determine the load power supply restoration order according to the multiplication result. The larger the calculation result, the more priority is given to restoring the load power supply.

[0062] It can be understood that the specific values of the first index value, the second index value and the weights are set according to the actual application, and this embodiment does not limit this.

[0063] In some embodiments, Step 3.2 specifically includes: Divide the loads according to the sum of the capacities of network-forming DGs and the constraint conditions of the total power supply load capacity of the load in the preset time period, and obtain multiple load sets; Determine the load power supply order according to the load levels in multiple load sets, and allocate the recoverable load capacity according to the load levels.

[0064] It can be allocated proportionally or according to the load level weights.

[0065] In this embodiment, an important level load priority power supply restoration strategy for the island is constructed based on network-forming DGs, which improves the level of local and nearby consumption of new energy and the continuous power supply ability of important loads.

[0066] Step 4: When there is no connection between the power outage area and other areas of the distribution network, detect the status of the no-voltage reclosing of the switch upstream of the fault point, and determine the power supply restoration strategy according to the type of fault and the status of the no-voltage reclosing.

[0067] No connection means that there is no direct electrical connection between certain areas or lines in the power grid, or there is no backup power supply path. These areas or lines are independent during normal operation and cannot be supported by other lines or power sources for power supply.

[0068] Preferably, when there is no connection, the power supply restoration strategy includes instantaneous faults and permanent faults. Step 4 specifically includes: Step 4.1: Power supply restoration for instantaneous faults when there is no connection, including: 1) If it is determined that the instantaneous fault reclosing is successful according to the type of fault and the status of the no-voltage reclosing, restore the power supply from the switch on the island power source side to the load in the bus area; 2) The grid-connected DG of the active connection and disconnection type from the switch on the island power source side to the bus area is fully grid-connected when the system voltage meets the condition of [-5%, +5%]; 3) The switch on the island power source side checks the synchronization and closes the switch to restore the power supply to the load that could not be preferentially restored in step 3 within the island area; 4) The switch on the island load side is closed, and the grid-connected DG of the active connection and disconnection type from the switch on the island load side to the end area is fully grid-connected when the system voltage meets the condition of [-5%, +5%]; 5) All the loads on the instantaneous fault line are restored to power supply.

[0069] Step 4.2: Power supply restoration for permanent faults when there is no connection, including: 1) If it is determined that the permanent fault reclosing fails according to the type of fault and the status of the no-voltage reclosing, restore the power supply from the switch on the island power source side to the load in the bus area to lose power again; 2) When the adjacent section of the island contains grid-connected DG, that is, when there is grid-connected DG directly connected to the island area, it is fully grid-connected, otherwise the power supply restoration process ends; 3) After the grid-connected DG is fully grid-connected, update the recoverable capacity margin based on the grid-connected capacity of the grid-connected DG; 4) Judge whether there is a recoverable section based on the power supply restoration capacity constraint condition (10). When there is a recoverable section, cut off the non-recoverable load based on the source-load balance, and the phased power restoration is completed; 5) Circularly search whether there is grid-connected DG directly connected to the island area, and stage-by-stage restore the load in the area connected to the island until there is no recoverable section.

[0070] Step 5: When there is a connection between the power outage area and other areas of the distribution network, determine the optimal connection switch according to the power of the connection line and the power outage load. After cutting off the irrecoverable section, close the optimal connection switch. Based on the capacity of adjacent grid-connected DGs, achieve staged power restoration by cyclically cutting off irrecoverable loads, connecting grid-connected DGs to the grid, and updating the recoverable capacity until there is no irrecoverable section.

[0071] Step 5.1: Determine the optimal connection switch according to the power of the connection line and the power outage load. Step 5.1 specifically includes: Step 5.1.1: Calculate the recoverable capacity after the grid-connected DG connected to the island is connected to the grid.

[0072] Preferably, the recoverable capacity after the grid-connected DG connected to the island is connected to the grid includes: (6) In the formula, is the maximum value of the recoverable capacity, is the active power before the fault of the grid-connected DG in the non-fault power outage section connected to the island area, is the set of non-fault power outage sections connected to the island area; is the proportion of the active power before the fault that can be output within the preset time when the PCC (Point of Common Coupling) voltage reaches the normal operation area, can take the value of 0.8, and the preset time is set according to actual needs.

[0073] It can be understood that the recoverable capacity in formula (6) is the recoverable capacity after the grid-connected DG connected to the island is connected to the grid.

[0074] Step 5.1.2: Calculate the maximum transfer power of each connection line before power restoration.

[0075] Preferably, calculate the maximum transfer power of the connection line before power restoration (i.e., transfer) according to the following formula: (7) In the formula, is the maximum transfer power of connection line n; is the rated power of connection line n; is the load power of connection line n before transfer.

[0076] Step 5.1.3: Calculate the maximum recovery ability of the maximum transfer power of each connection line according to the recoverable capacity and the maximum transfer power of each connection line before power restoration, and determine the optimal connection switch according to the maximum recovery ability of the maximum transfer power of each connection line.

[0077] Calculate the sum of the recoverable capacity and the maximum power transfer capacity of each tie line before power restoration, and select the tie line corresponding to the maximum sum as the optimal tie switch.

[0078] Calculate the maximum recovery capacity of the maximum power transfer capacity of the tie line through formulas (6) and (7): (8) In the formula, is the maximum recovery capacity of the maximum power transfer capacity of the tie line, that is, the recoverable capacity considering the remaining capacity of the tie switch. Select the tie line with the maximum capacity as the optimal tie switch.

[0079] Step 5.2: Update the sum of the power of the power-off loads in the non-faulty sections: (9) In the formula, is the sum of the power of the power-off loads in the non-faulty sections, is the power of load in non-faulty section i, m is the set of all non-faulty sections, and i is the i-th section in the non-faulty sections.

[0080] When the maximum recovery capacity of the maximum power transfer capacity of the tie line where the optimal tie switch is located is less than the sum of the power of the power-off loads in the non-faulty sections, conduct staged power restoration until there is no recoverable area. Step 5.3 specifically includes: Step 5.3.1: Determine the non-recoverable sections according to the power supply recovery capacity constraint conditions, and cut off the non-recoverable sections.

[0081] The power supply recovery capacity constraint conditions are: (10) In the formula, is the load capacity at time t, is the maximum power transfer capacity of tie line n.

[0082] Step 5.3.2: Close the optimal tie switch, and update the load capacity and recoverable capacity of the unrecovered sections.

[0083] Preferably, when there is a tie, the staged update of the load capacity and recoverable capacity of the unrecovered sections includes: Update the load capacity of the unrecovered sections according to the following formula: (11) In the formula, is the load capacity at time t, that is, the load capacity of the unrecovered sections, is the sum of the power of the power-off loads in the non-faulty sections, is the load power of tie line n before power transfer, is the set of sections that have been powered on.

[0084] Step 5.3.3: Connect the grid-connected DG with the grid and update the recoverable capacity.

[0085] Based on the source-load balance constraint condition, the optimal tie switch is closed, and other tie switches are blocked. The recoverable capacity of the remaining capacity of the tie switch is updated according to the following formula: (12) In the formula, is the recoverable capacity, is the set of power supply restored sections, is the maximum transfer power of tie line n, is the pre-fault active power of the grid-connected distributed power source in the non-fault power-loss section connected to the island area, is the proportion of the pre-fault active power that can be output within the preset time period when the voltage at the common connection point reaches the normal operation area.

[0086] Step 5.3.4: Update the sum of the power of the power-loss loads in the non-fault sections. According to the updated sum of the power of the power-loss loads in the non-fault sections and the updated recoverable capacity, judge whether to perform sectional power restoration, and repeat Steps 5.3.1 to 5.3.4 until there is no recoverable area.

[0087] Step 5.4: When restoring to the section adjacent to the island, the switch connecting the island area and the switch in the restored area of the closed tie switch checks the synchronization for grid connection.

[0088] Step 6: When restoring to the section adjacent to the island, the switch connecting the island area and the switch in the restored area of the closed tie switch checks the synchronization for grid connection, and supply power to the remaining loads in the island according to the load power supply restoration sequence and the updated recoverable capacity.

[0089] Checking the synchronization for grid connection means that during the grid connection operation, by detecting whether the voltage amplitude, frequency, and phase angle on both sides of the grid connection point meet the synchronization conditions, it is determined whether to close the switch to complete the grid connection.

[0090] In this embodiment, after the load restoration in the island is completed, due to capacity limitations, there are some loads inside, and all external loads cannot be restored. At this time, the minimum restoration unit operates in the form of an island. Since the tie switch is connected to the power source on the other side, power supply support can be provided through the closing of the tie switch, and some load power supply can be restored (related to the capacity provided by the power source on the other side). When the tie switch is closed and the restored area is adjacent to the island, the connected switch checks the synchronization and closes at this time.

[0091] As Figure 3 shown, Figure 3 is a schematic diagram of a typical multi-tie grid structure with distributed power sources connected to the distribution network. In Figure 3Among them, the self-healing integrated terminal can achieve information interaction through 5G wireless communication. Among them, DG1, DG3, and DG4 are all grid-connected DGs, with rated output capacities of 2MW, 3MW, and 2MW respectively. DG2 is a network-forming DG with a rated output capacity of 2MW. The maximum transfer powers of the tie switches LSW1 and LSW2 are 4.5MW and 4MW respectively. Taking the fault between the main line section switches FS1 and FS2 as an example, the power supply restoration steps are as follows in stages: Step 1: The self-healing integrated terminal obtains the signal of successful isolation of the fault section and determines the power outage area.

[0092] The fault point is located within the minimum restoration unit 2, and the power outage area is the minimum restoration units 3-9; the node information includes that DG1, DG3, and DG4 are all grid-connected DGs, and DG2 is a network-forming DG.

[0093] Specifically, the main line section switches FD1 and FD2 and the branch switch FS1 protection actuate and trip to complete the isolation of the fault section.

[0094] Step 2: Cut off all grid-connected distributed power sources connected to the nodes in the power outage area that have received the signal of successful isolation.

[0095] After the switches YS1, YS3, and YS4 at the connection between the grid-connected DGs DG1, DG3, and DG4 in the non-fault power outage area and the system receive the signal of successful fault isolation, they trip actively, and DG1, DG3, and DG4 are disconnected from the grid.

[0096] Step 3: Since the power outage area contains the network-forming DG2 node, therefore, a planned island is constructed based on the source-load balance condition. Within each planned island, the power supply restoration order of the loads is determined according to the load levels, and the minimum restoration unit with the highest load level is preferentially restored.

[0097] Step 3.1, Update the load power of the minimum restoration unit according to formula (1) based on the sectional information at the fault moment. The sectional information at the fault moment includes DG power, load power, tie switch capacity, etc. The calculation results are shown in Table 2.

[0098] Table 2

[0099] Step 3.2, When the load is greater than the load power of the minimum restoration unit, determine the power supply restoration order of the loads according to the total power supply capacity of the loads in the preset time period, the load levels, and the corresponding constraint conditions for different loads.

[0100] Figure 3 Among them, the sum of the load powers of the minimum restoration unit 8 is 2MW, which satisfies the constraint condition (2) of not being greater than the rated capacity of the network-forming DG2. The branch switch FS2 trips, and the minimum restoration unit 8 operates in an island mode, that is, the loads within the minimum restoration unit are restored.

[0101] Figure 3 There is a connection network framework, so step 4 is skipped and step 5 is carried out.

[0102] Step 5: When there is a connection between the power outage area and other areas of the distribution network, determine the optimal connection switch according to the connection line and the power of the power outage load. After cutting off the irrecoverable section, close the optimal connection switch. Based on the capacity of adjacent grid-connected DGs, realize staged power restoration by cyclically cutting off irrecoverable loads, connecting grid-connected DGs to the grid, and updating the recoverable capacity until there is no irrecoverable section; when restoring to the section adjacent to the island, the switch connecting the island area and the area where the connection switch is closed and restored checks synchronization and is connected to the grid.

[0103] Step 5.1: Calculate the maximum restoration capabilities of the maximum transfer powers of connection line 1 and connection line 2 respectively, and select the connection switch LSW2 with the maximum restoration capability as the optimal connection switch. The specific comparison method is as follows: , , , In the formula, is the maximum restoration capability of the maximum transfer power of connection line 1, is the maximum restoration capability of the maximum transfer power of connection line 2.

[0104] Step 5.2: Update the sum of the power of the power outage loads in the non-fault section according to Equation (9): , Step 5.3: When the maximum restoration capability of the maximum transfer power of the connection line where the optimal connection switch is located is less than the power of the power outage loads in the non-fault section, carry out staged power restoration until there is no recoverable area.

[0105] Because is greater than , it is impossible to restore all non-fault power outage areas at one time. Step 5.3 specifically includes: Step 5.3.1: Determine the irrecoverable section according to the power supply restoration capacity constraint condition, and cut off the irrecoverable section.

[0106] Specifically, obtain according to formula (10): , It can be seen that since the sum of the load capacities of the minimum restoration units 5 and 9 is less than the maximum transfer power of the tie line 2, and the sum of the load capacities of the minimum restoration units 4, 5, and 9 is greater than the maximum transfer power of the tie line 2. Therefore, the main line sectionalizing switch FD4 trips to cut off the minimum restoration units 4 and 7 in the unrecoverable section to meet the power supply restoration capacity constraint conditions.

[0107] Step 5.3.2: Close the optimal tie switch and update the load capacity of the unrecovered section.

[0108] Specifically, close the tie switch LSW2 and block the tie switch LSW1 to prevent the two tie switches from closing simultaneously, as simultaneous closing and loop operation may cause non-synchronous closing. The power supply restoration of the minimum restoration units 5 and 9 is achieved, and the load capacity of the unrecovered section is updated according to Equation (11): , Step 5.3.3: Connect the network-connected DG to the grid and update the recoverable capacity.

[0109] Close the branch switch YS4, and the DG4 outputs power to the grid. Update the recoverable capacity according to Equation (12): , Step 5.3.4: Update the sum of the power of the lost loads in the non-faulty sections. Determine whether to perform sectional power restoration based on the updated sum of the power of the lost loads in the non-faulty sections and the updated recoverable capacity. Repeat Steps 5.3.1 to 5.3.4 until there is no recoverable area.

[0110] Since the sum of the lost load capacities in the unrecovered sections 3, 4, and 7 is 4 MW, which is greater than the recoverable capacity, it is impossible to restore all non-faulty lost power areas at once. The main line sectionalizing switch FD3 trips to cut off the minimum restoration unit 3 in the unrecoverable section to meet the power supply restoration capacity constraint conditions: , Next, close the main line sectionalizing switch FD4, and the power supply of the minimum restoration units 4 and 7 is restored. Update the load capacity of the unrecovered section: , Next, close the branch switch YS3, and the DG3 outputs power to the grid. Update the recoverable capacity: , Next, only the minimum restoration unit 3 in the non-faulty lost power area remains unrecovered, meeting the power supply restoration capacity constraint conditions: , Next, close the main line sectionalizing switch FD3, and the power supply of the minimum restoration unit 3 is restored, and the loads in all lost power areas are restored.

[0111] Step 6: The switch FS2 for synchronism checking and closing when the island is connected to the system, and the power supply restoration process technology.

[0112] Embodiment 2 of the present invention provides a distribution network power supply restoration system considering the coordination of multiple types of distributed power sources, which operates the distribution network power supply restoration method considering the coordination of multiple types of distributed power sources as described in Embodiment 1. The system includes: A determination module, configured to obtain a signal indicating successful isolation of a fault section and determine a power outage area; An excision module, configured to excise all grid-connected distributed power sources connected to the node that receives the isolation success signal within the power outage area; A construction module, configured to construct a planned island when the power outage area includes a grid-forming distributed power source node, determine the load power supply restoration sequence within each planned island according to the load level, and preferentially restore the smallest restoration unit with the highest load level; A first restoration module, configured to detect the status of the no-voltage reclosing of the switch upstream of the fault point when the power outage area has no connection with other areas of the distribution network, and determine a power supply restoration strategy according to the fault type and the status of the no-voltage reclosing; A second restoration module, configured to determine an optimal connection switch according to the connection line and the power of the power outage load when the power outage area has a connection with other areas of the distribution network, close the optimal connection switch after excising the non-restorable section, and based on the capacity of adjacent grid-connected distributed power sources, realize staged power restoration by cyclically excising non-restorable loads, connecting grid-connected distributed power sources to the grid, and updating the restorable capacity until there is no non-restorable section; A third restoration module, configured to, when restoring to the section adjacent to the island, check the synchronization and grid connection of the switch connecting the island area and the switch of the restored area where the connection switch is closed, and supply power to the remaining loads within the island according to the load power supply restoration sequence and the updated restorable capacity.

[0113] Regarding the system in the above embodiments, the specific manners in which each unit performs operations have been described in detail in the embodiments related to the method, and will not be elaborated herein.

[0114] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements the distribution network power supply restoration method considering the coordination of multiple types of distributed power sources described in Embodiment 1.

[0115] In some embodiments, the electronic device may be a self-healing integrated terminal.

[0116] Embodiment 4 of the present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, it implements a power supply restoration method for a distribution network considering coordinated operation of multiple types of distributed power sources as described in Embodiment 1.

[0117] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0118] This application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of this application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0119] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including instruction means, and the instruction means implements the specified functions in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0120] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the specified functions in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0121] The above embodiments of the present invention have been described in conjunction with the accompanying drawings, but the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the present invention and the claims. All of these fall within the protection scope of the present invention.

Claims

1. A power supply restoration method for a distribution network considering the coordination of multiple types of distributed power sources, characterized in that Including: Obtain the successful signal of isolating the fault section and determine the power outage area; Cut off all grid-connected distributed power sources connected to the node that receives the isolation success signal within the power outage area; When the power outage area includes network-forming distributed power source nodes, construct a planned island, determine the load power supply restoration sequence according to the load level within each planned island, and preferentially restore the smallest restoration unit with the highest load level; When there is no connection between the power outage area and other areas of the distribution network, detect the status of the no-voltage reclosing of the switch upstream of the fault point, and determine the power supply restoration strategy according to the fault type and the status of the no-voltage reclosing; When there is a connection between the power outage area and other areas of the distribution network, determine the optimal connection switch according to the connection line and the power of the power outage load, cut off the non-recoverable section and then close the optimal connection switch, and based on the capacity of adjacent grid-connected distributed power sources, realize staged power restoration by cyclically cutting off non-recoverable loads, grid-connecting grid-connected distributed power sources and updating the recoverable capacity until there is no non-recoverable section; When restoring to the section adjacent to the island, the switch connecting the island area and the area where the connection switch is closed for restoration checks synchronization and is grid-connected, and the remaining loads within the island are supplied with power according to the load power supply restoration sequence and the updated recoverable capacity.

2. The method for restoring power supply to a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, wherein: The planned island includes multiple smallest restoration units, and determining the load power supply restoration sequence according to the load level within each planned island includes: Calculate the load power of each smallest restoration unit; When the load is greater than or equal to the load power of the smallest restoration unit, determine the load power supply restoration sequence according to the total power supply load capacity, load level and corresponding constraint conditions of different loads within the preset time period.

3. The method for restoring power supply to a distribution network considering the coordination of multiple types of distributed power sources according to claim 2, wherein: The constraint condition for the total power supply load capacity of the load within the preset time period is that the total power supply load capacity of the load within the preset time period is less than the capacity of the network-forming distributed power source. Determining the load power supply restoration sequence according to the total power supply load capacity, load level and corresponding constraint conditions of different loads includes: Divide the loads according to the sum of the capacities of the network-forming distributed power sources and the constraint condition of the total power supply load capacity of the load within the preset time period to obtain multiple load sets; Determine the load power supply sequence according to the load level among multiple load sets, and allocate the recoverable load capacity according to the load level.

4. The method for restoring power supply to a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, wherein: The power supply restoration strategy includes instantaneous faults and permanent faults.

5. The method for restoring power supply to a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, wherein: Determining the optimal connection switch according to the connection line and the power of the power outage load includes: Calculate the recoverable capacity after grid-connecting the grid-connected distributed power sources connected to the island; Calculate the maximum transfer power of each connection line before power supply restoration; Calculate the maximum recovery capacity of the maximum transfer power of each tie line according to the recoverable capacity and the maximum transfer power of each tie line before power restoration, and determine the optimal tie switch according to the maximum recovery capacity of the maximum transfer power of each tie line.

6. The method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to claim 5, characterized in that: Calculating the maximum recovery capacity of the maximum transfer power of each tie line according to the recoverable capacity and the maximum transfer power of each tie line before power restoration, and determining the optimal tie switch according to the maximum recovery capacity of the maximum transfer power of each tie line, including: Sum the recoverable capacity and the maximum transfer power of each tie line before power restoration to obtain the maximum recovery capacity of the maximum transfer power of each tie line; Select the tie line corresponding to the maximum value among the maximum recovery capacities as the optimal tie switch.

7. The method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, characterized in that: After the grid-connected distributed power sources are connected to the grid and the recoverable capacity is updated, the method further includes: Update the sum of the power of the lost-load in the non-faulty section, and determine whether to conduct staged power restoration according to the updated sum of the power of the lost-load in the non-faulty section and the updated recoverable capacity.

8. The method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, characterized in that: Update the recoverable capacity according to the following formula: ， In the formula, is the recoverable capacity, is the set of sections with restored power supply, is the maximum transfer power of tie line n, is the pre-fault active power of grid-connected distributed power sources in the non-faulty power-loss sections connected to the island area, is the proportion of pre-fault active power that can be output within the preset time period when the voltage at the point of common coupling reaches the normal operation area.

9. The method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to claim 1, characterized in that: The method further includes: Judge whether there is a recoverable section based on the power supply recovery capacity constraint condition, and the power supply recovery capacity constraint condition is that the load capacity in a preset time period is less than or equal to the maximum transfer power of the tie line.

10. A distribution network power supply restoration system considering the coordination of multiple types of distributed power sources, characterized in that, The system includes: A determination module, configured to obtain a signal indicating successful isolation of a faulty section and determine a power-lost area; An excision module, configured to excise all grid-connected distributed power sources connected to the node that receives the isolation success signal in the power-lost area; A construction module, configured to construct a planned island when the power-lost area includes a grid-forming distributed power source node, determine the load power supply recovery sequence according to the load level in each planned island, and preferentially restore the smallest recovery unit with the highest load level; A first recovery module, configured to detect the status of the no-voltage reclosing of the switch upstream of the fault point when the power-lost area has no connection with other areas of the distribution network, and determine a power supply recovery strategy according to the type of fault and the status of the no-voltage reclosing; A second recovery module, configured to determine an optimal tie switch according to the tie line and the power of the lost-load when the power-lost area has a connection with other areas of the distribution network, close the optimal tie switch after excising the non-recoverable section, and realize staged power restoration by cyclically excising non-recoverable loads, connecting grid-connected distributed power sources to the grid and updating the recoverable capacity until there is no recoverable section; A third recovery module, configured to when restoring to the section adjacent to the island, synchronize the switch connecting the island area and the area where the tie switch is closed for grid connection, and supply power to the remaining loads in the island according to the load power supply recovery sequence and the updated recoverable capacity.

11. An electronic device, comprising a processor and a storage medium; characterized in that: The storage medium is used for storing instructions; The processor is used for operating according to the instructions to execute the steps of the method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to any one of claims 1-9.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, the steps of the method for restoring power supply of a distribution network considering the coordination of multiple types of distributed power sources according to any one of claims 1-9 are implemented.

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