Coordinated parameter setting method for equivalent parameters of multi-infeed weak grid new energy station

Abstract

This disclosure provides a method for collaborative tuning of equivalent parameters for renewable energy power plants in multi-infeed weak grids. The method includes establishing a joint state sequence of topology and operation for multiple power plants throughout the entire fault process, encompassing topology and operational status information covering each state stage from before the fault to after recovery; identifying the continuous migration process of power plant coupling categories, forming a continuous migration chain including coupling category migration nodes, path loss nodes, major support change nodes, and coupling category recovery nodes; using the coupling category migration nodes in the continuous migration chain as the equivalent boundary reconstruction time, performing phased reconstruction of the equivalent boundaries for all power plants; conducting cross-stage collaborative parameter tuning to construct an equivalent model for renewable energy power plants in multi-infeed weak grids, and maintaining or updating the model state during reclosing anomalies and subsequent coupling category migrations. This method solves the problem of the inability to synchronously reconstruct the equivalent boundaries during the dynamic fault process, improving the accuracy and adaptability of the equivalent model for renewable energy power plants in multi-infeed weak grids.

Description

Technical Field

[0001] This disclosure relates to the field of power system automation control technology, and in particular to a method for coordinated tuning of equivalent parameters of new energy power plants in multi-infeed weak power grids. Background Technology

[0002] With the large-scale grid connection of new energy power generation such as wind power and photovoltaics, the operating characteristics of the power system have undergone profound changes. In multi-infeed weak grid scenarios, multiple new energy power plants are connected to the grid through shared double-circuit transmission lines, segmented busbars, or main transformers. The power plants form complex electrical coupling relationships through common transmission channels, which can be classified into three types: direct coupling, indirect coupling, and weak correlation. Existing solutions typically pre-classify the coupling categories of the power plants and establish equivalent models and set control parameters accordingly.

[0003] However, during the dynamic process of fault clearing and automatic reclosing, the coupling category of a power station is not fixed but continuously shifts within the same disturbance. For example, in multiple power stations sharing a double-circuit line, after one circuit is cleared, stations that originally transmitted power through different channels may be forced to merge into the same remaining channel. After successful reclosing, the coupling relationship is restored, and indirectly coupled stations may instantly become directly coupled stations, while weakly associated stations may become major participants in voltage support. Even with updates to local parameter sets, existing technologies struggle to cover situations where transmitting impedance, power flow distribution, voltage support paths, and control action sequences change simultaneously. The withdrawal of a single common line can cause a global reconstruction of the equivalent boundaries of all power stations.

[0004] Therefore, there is an urgent need for a method for coordinated tuning of equivalent parameters of new energy power plants in multi-infeed weak power grids, so as to realize the synchronous reconstruction of equivalent boundaries and coordinated parameters as the coupling relationship of the power plants migrates throughout the fault process. Summary of the Invention

[0005] In view of this, in order to solve the problems caused by the existing technology, this disclosure provides a method for coordinated tuning of equivalent parameters of new energy power plants in multi-infeed weak grids.

[0006] In a first aspect, this disclosure provides a method for coordinated tuning of equivalent parameters of renewable energy power plants in multi-infeed weak power grids, the method comprising:

[0007] S1. Establish a joint state sequence of topology and operation for multiple sites throughout the entire fault process. The joint state sequence of topology and operation includes topology information and operation status information covering each state stage from before the fault to after the fault recovery. The event type and transition time that trigger the state transition are marked between adjacent stages.

[0008] S2. Based on the electrical connection status sequence of the multiple stations, identify the continuous migration process of station coupling categories, and form a continuous migration chain including coupling category migration nodes, path loss nodes, main support change nodes, and coupling category recovery nodes. The coupling categories include direct coupling, indirect coupling, and weak association.

[0009] S3. Using the coupled category migration nodes in the continuous migration chain as the time of the equivalent boundary reconstruction, perform phased reconstruction of the equivalent boundary of the entire station and output the phased reconstruction result of the equivalent boundary of the entire station.

[0010] S4. Based on the phased full-site equivalent boundary reconstruction results, conduct cross-stage collaborative parameter tuning to form a cross-stage collaborative parameter set corresponding to each stage of the continuous migration chain.

[0011] S5. Based on the cross-stage collaborative parameter group, construct an equivalent model of new energy power stations in multi-infeed weak grids. The equivalent model calls the corresponding parameter group according to the currently activated state stage, and maintains or updates the model state when there is a reclosing anomaly or the coupling category migrates again, and outputs all model parameters and state information.

[0012] Optionally, S1 includes:

[0013] S1.1 Obtain the electrical basic parameters of each new energy power station and the fault response records during the fault period;

[0014] S1.2 Based on the electrical basic parameters and fault response records, the occurrence of line faults, protection disconnection, start of remaining channel takeover, automatic reclosing initiation, successful reclosing and failed reclosing are taken as forced state boundaries. When all state boundaries are determined, the corresponding state boundary markers are added to the records at that moment.

[0015] S1.3. Based on the adjacent state boundaries, the system is divided into the following stages: pre-fault stage, fault occurrence stage, protection clearance stage, remaining channel takeover stage, automatic reclosing stage, and fault recovery stage after successful reclosing or continuous fault stage after failed reclosing. When reclosing is successful, the system proceeds to the fault recovery stage; when reclosing fails, the system proceeds to the continuous fault stage. Within each stage, the system tracks the actual transmission path from each station to the common grid connection point and registers the topology and operating status information within that stage.

[0016] S1.4 Connect each stage sequentially according to the time sequence of state occurrence, and mark the event type that triggers the state transition between adjacent stages to form the multi-site topology and operation joint state sequence.

[0017] Optionally, S2 includes:

[0018] S2.1 According to each state stage in the joint state sequence of topology and operation, track the actual electrical connection path between each station and the common grid connection point, and extract electrical correlation feature quantities to characterize the structural connection and dynamic support relationship between stations. The electrical correlation feature quantities include the proportion of shared transmission paths, normalized electrical distance, consistency of power flow convergence direction, consistency of voltage change transmission, and reactive power support acceptance.

[0019] S2.2 For each pair of stations in each state stage, calculate the comprehensive coupling strength based on the electrical association characteristic quantity, and classify each pair of stations into coupling categories of direct coupling, indirect coupling, or weak association.

[0020] S2.3 Identify migration events between adjacent state stages for each station, including coupling category migration, path loss, and coupling category recovery. Record the corresponding migration nodes and their coupling categories before and after migration, as well as the migration time. At the same time, determine the main voltage support in each stage.

[0021] S2.4. According to the time sequence of the entire fault process, connect the coupling categories and migration times before and after migration at each migration node of each station in sequence to form the continuous migration chain.

[0022] Optionally, S3 includes:

[0023] S3.1. Using the coupling category migration node in the continuous migration chain as the time of equivalent boundary reconstruction, establish common coupling boundary, associated correction boundary and core tuning boundary according to the differences in the power station output path and voltage support role;

[0024] S3.2 For a station that corresponds to only one boundary, its boundary affiliation is directly determined according to the current actual transmission path; for a station that is associated with multiple boundaries at the same time, an affiliation determination is performed to assign the station to the boundary whose affiliation is determined.

[0025] S3.3 For common coupling boundaries, the equivalent impedance is reconstructed according to the actual electrical relationship of parallel branches and series common paths, and the impedance of the associated correction boundary retains its independent transfer impedance to the convergence point of the common coupling boundary.

[0026] S3.4. Trace the active power flow path, reverse the reactive power support path, determine the time center of gravity of reactive power support of each station as the equivalent response time, determine the support input order according to the equivalent response time, and write it together with the topology switching order in the continuous migration chain into the control acceptance relationship table.

[0027] S3.5. According to the time sequence of the continuous migration chain, connect the common coupling boundary, the associated correction boundary and the core tuning boundary of each stage in sequence, and attach reconstruction parameters to each boundary. Together with the control acceptance relationship table, output the reconstruction result of the phased full-site equivalent boundary.

[0028] Optionally, the attribution determination includes:

[0029] When the voltage support contribution ratio of the station is not lower than the set threshold, it is directly included in the core setting boundary;

[0030] Otherwise, the degree of affiliation is calculated based on the proportion of shared transmission paths between the station and other stations within the boundary, the overall coupling strength, the consistency of voltage changes, and the proportion of voltage support contribution of the station, and it is assigned to the boundary with the highest degree of affiliation.

[0031] Optionally, S4 includes:

[0032] S4.1 Read the detailed information of each boundary one by one according to each state stage. Each boundary corresponds to each equivalent unit. Determine the basic parameters of each equivalent unit, including the equivalent impedance.

[0033] S4.2 Determine the remaining reactive power support capacity and support deployment sequence of each equivalent unit. After the preceding equivalent unit reaches the remaining reactive power support boundary, the subsequent equivalent unit shall take over. When multiple stations converge into the same remaining channel, they shall be uniformly constrained by the carrying capacity of the common channel.

[0034] S4.3 For topology-altering parameters, switch them immediately according to the actual position of the circuit breaker. For continuous parameters that need to be gradually withdrawn as the power flow recovers after successful reclosing, perform a gradual conversion and determine the conversion relationship between parameter groups.

[0035] S4.4. According to the time sequence of the entire fault process, establish a parameter group for each stage based on the transformation relationship, including the activation conditions and all tuning parameters, to form a cross-stage collaborative parameter group corresponding to each stage of the continuous migration chain.

[0036] Optionally, S5 includes:

[0037] S5.1 Configure the activation conditions, maintenance conditions and exit conditions for the parameter groups in each state stage. Only one parameter group or one transformation relationship is allowed to be active at the same time. The active transformation relationship calculates the current call value in real time to form a collaborative parameter activation sequence for the entire fault process.

[0038] S5.2 Construct an equivalent model, establish corresponding equivalent units according to the current active boundary, one equivalent unit for each boundary, write tuning parameters to each equivalent unit, calculate the internal port voltage of each equivalent unit based on the equivalent impedance, perform power constraints within the capacity range, and put each support unit into the support unit in sequence according to the support input order;

[0039] S5.3. Perform appropriate maintenance or update processing on the model state under abnormal scenarios;

[0040] S5.4 Perform a consistency check on the model results. After the consistency check passes, output all model parameters and status information in chronological order.

[0041] Optionally, the process of maintaining or updating the model state under abnormal scenarios includes:

[0042] When reclosing fails, the current parameter status of the remaining channels is maintained;

[0043] When the circuit breaker trips again after a successful reclosing, the switching is terminated and the temporary parameter group is reactivated.

[0044] When the circuit breaker has been closed but the original channel has not yet received power flow, maintain the current reconfiguration boundary;

[0045] When a new coupling category migration occurs at the site, the boundaries are redefined and the activation order of subsequent parameters is updated, starting from the current model state.

[0046] In a second aspect, this disclosure provides an electronic device including a memory and at least one processor, the memory storing a computer program, and the processor executing the computer program to implement the method of the first aspect described above.

[0047] Thirdly, this disclosure provides a non-transitory computer-readable storage medium storing a computer program that, when executed, implements the method described in the first aspect.

[0048] The beneficial effects of this disclosure are that, compared with the prior art, this disclosure has the following advantages:

[0049] By establishing an electrical connection state sequence covering the entire fault process, a complete state awareness basis is provided for equivalent boundary reconstruction. Based on this, the continuous migration process of the station's coupling categories is identified, forming a continuous migration chain that fully depicts the evolution trajectory of coupling relationships during the fault. Using the coupling category migration node as the reconstruction moment, a phased reconstruction of the equivalent boundary of the entire station is performed. Based on the reconstruction results, cross-stage collaborative parameter tuning is carried out, forming a collaborative parameter set corresponding to each stage. The equivalent model calls the corresponding parameter set according to the current state stage and maintains or updates the model state under abnormal scenarios, achieving dynamic following between the equivalent boundary and collaborative parameters. This effectively solves the technical problem that the equivalent boundary cannot be synchronously reconstructed during the dynamic fault process, significantly improving the accuracy and adaptability of the equivalent model for multi-infeed weak grid renewable energy stations. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0051] Figure 1 A flowchart of the method for coordinated tuning of equivalent parameters of new energy power plants with multiple infeed weak grids provided in this disclosure is shown.

[0052] Figure 2 A flowchart illustrating the site coupling category identification and continuous migration chain formation provided in an embodiment of this disclosure is shown.

[0053] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0054] The present disclosure will be further described below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present disclosure more clearly, and should not be used to limit the scope of protection of the present disclosure.

[0055] Figure 1 The flowchart of the method for coordinated tuning of equivalent parameters of multi-infeed weak grid renewable energy power stations provided in this disclosure is as follows: Figure 1 As shown, the method may include the following steps:

[0056] S1: Establish a joint state sequence of topology and operation of multiple sites throughout the entire fault process, including topology and operation status information covering each state stage from before the fault to after the fault recovery. The event type and transition time that trigger the state transition are marked between adjacent stages.

[0057] S1.1: Obtain the electrical basic parameters of each new energy power station and the fault response records during the fault period.

[0058] Acquire the basic electrical parameters of each renewable energy power station, including grid connection location information, primary wiring relationships, on-site equipment composition, equivalent capacity, transformer impedance, reactive power compensation configuration, dual-circuit outgoing line connection relationships, segmented bus operation modes, and main transformer load-bearing relationships. Simultaneously, collect fault response records during fault periods, including protection action signals, circuit breaker position information, and measured electrical quantities. This information is retrieved from the renewable energy power station's monitoring and data acquisition system, fault recording device, and energy management system.

[0059] Based on the acquired data, a unique object identifier is assigned to each circuit breaker, each busbar section, and each transmission line, using the substation, busbar, main transformer, transmission line, and common grid connection point as a continuous connection hierarchy. Following a unified chronological order, the circuit breaker location, substation transmission path, line carrying capacity, common grid connection point voltage, substation active power output, reactive power output, and control action timing are associated with the corresponding object identifier. During the recording process, both the normal connection relationships before the fault and the actual connection changes after the fault are retained, forming a multi-substation electrical infrastructure record covering the entire fault process. This record includes not only data after the fault occurred but also data under normal conditions before the fault, providing a reference benchmark for subsequent state boundary determination.

[0060] S1.2: Take the occurrence of line fault, protection disconnection, start of remaining channel takeover, automatic reclosing start, reclosing success and reclosing failure as forced state boundaries. When all state boundaries are determined, add the corresponding state boundary mark to the record at that moment.

[0061] Based on the obtained electrical infrastructure records from multiple substations, the effective state boundary moments throughout the fault process are determined. The occurrence of a line fault, protection disconnection, commencement of remaining channel takeover, initiation of automatic reclosing, successful reclosing, and reclosing failure are considered mandatory state boundaries. For transient processes such as power flow redistribution after protection disconnection and incomplete restoration of the outgoing path after reclosing, a weighted comprehensive judgment method is used to determine whether candidate moments constitute effective state boundaries.

[0062] Specifically, for each candidate moment, the position of the critical circuit breaker is first checked. If a critical circuit breaker has changed position, the switch position indication value is set to 1; otherwise, it is set to 0. Simultaneously, the deviations of impedance change, power change, and voltage change from their respective reference values ​​are calculated: for impedance change, the absolute value of the difference between the current impedance and the reference impedance is calculated as the ratio of the reference impedance to the current impedance; for power change, the absolute value of the difference between the current power and the pre-fault steady-state power is calculated as the ratio of the rated power; for voltage change, the absolute value of the difference between the current voltage and the pre-fault steady-state voltage is calculated as the ratio of the rated voltage. The switch position indication value and the three deviation values ​​are then weighted and fused, with each weight ranging from 0.22 to 0.28, and normalized to a sum of 1. When the overall strength after fusion reaches the judgment threshold, the candidate moment is confirmed as the new state boundary. The judgment threshold can be set between 0.20 and 0.24 to ensure that the critical switch displacement can naturally form a boundary, while avoiding normal power fluctuations being segmented separately.

[0063] The above judgment method unifies switching actions and electrical quantity mutations into a dimensionless comprehensive change degree, enabling different types of physical events to be compared and integrated on the same scale. After determining all state boundaries, a corresponding state boundary marker is added for each recorded moment.

[0064] S1.3: Extract data according to the adjacent state boundaries, track the actual transmission path of each station to the public grid connection point in each stage, and register the topology information and operation status information in that stage.

[0065] Based on the boundaries of adjacent states, the system is divided into the following stages: pre-fault stage, fault occurrence stage, protection clearance stage, remaining channel takeover stage, automatic reclosing stage, and fault recovery stage after successful reclosing or persistent fault stage after failed reclosing. When reclosing is successful, the system proceeds to the fault recovery stage; when reclosing fails, the system proceeds to the persistent fault stage. Within each stage, the actual power transmission path from each substation to the common grid connection point is traced, and the circuit breaker location, connected bus, carrying main transformer, effective transmission line, line carrying capacity, and active and reactive power output of the substation are recorded.

[0066] During the tracking process, the integrity of the connection path is verified using real-time power balance relationships. For each state stage, the total active power injected by each substation is compared with the total active power carried by each transmitting line, and the active power losses of the lines and transformers are deducted for verification; similarly, the total reactive power injected by each substation is compared with the total reactive power carried by each transmitting line, and the net reactive power consumption of the lines and transformers is deducted for verification. If the active or reactive power deviation continuously exceeds the transient measurement allowable range during the stage, it is determined that there is an omission in the transmitting path for that stage. The transient measurement allowable range is calculated at 0.045 per unit value. Exceeding this limit indicates that the currently recorded connection path is inconsistent with the actual power flow direction, and the connection relationship needs to be corrected before re-verification. This verification method confirms the consistency between the transmitting path and the actual power flow direction at each stage by simultaneously verifying the active power transfer closure and the reactive power receiving closure.

[0067] After completing path tracing and power verification at all stages, a phased multi-site electrical connection status table is generated.

[0068] S1.4: Connect each stage sequentially according to the time sequence of state occurrence, and mark the event type that triggers the state transition between adjacent stages to form the multi-site topology and operation joint state sequence.

[0069] Based on a phased multi-site electrical connection status table, each phase is connected sequentially according to the time sequence of state occurrence. The event types triggering state transitions are marked between adjacent phases, including line fault, protection disconnection, remaining channel replacement, reclosing initiation, successful reclosing, failed reclosing, and re-tripping. The registered circuit breaker locations, site outgoing paths, line carrying capacity, common grid connection point voltage, site active power output, reactive power output, and control action times for each phase are connected sequentially according to time, forming a multi-site topology and operational joint state sequence covering the period from before the fault to after fault recovery.

[0070] Each stage in this sequence contains complete topological and operational status information, with clear transition types and times marked between adjacent stages. This joint state sequence serves as the sole input for subsequent identification of direct coupling, indirect coupling, and weakly correlated continuous migration relationships between stations.

[0071] S2: Based on the electrical connection status sequence of the multiple stations, identify the continuous migration process of station coupling categories, and form a continuous migration chain including coupling category migration nodes, path loss nodes, main support change nodes, and coupling category recovery nodes. The coupling categories include direct coupling, indirect coupling, and weak association.

[0072] S2.1: Track the actual electrical connection paths between each station and the common grid connection point, and extract electrical correlation features to characterize the structural connections and dynamic support relationships between stations.

[0073] Figure 2 A flowchart illustrating the site coupling category identification and continuous migration chain formation provided in this disclosure embodiment is shown, such as... Figure 2 As shown, based on the multi-station topology and joint operation state sequence, the actual electrical connection paths between each station and the common grid connection point are traced according to the pre-fault stage, fault occurrence stage, protection clearing stage, remaining channel takeover stage, automatic reclosing stage, and fault recovery stage. These paths include electrical nodes such as the in-station busbar, main transformer, and outgoing lines. For each pair of stations, electrical correlation features characterizing the structural connections and dynamic support relationships between stations are extracted, specifically including the following five items:

[0074] The first item is the proportion of shared transmission paths, which is determined according to the proportion of the impedance of the lines and transformers that the two stations share to the total impedance of the shorter transmission path. The value ranges from 0 to 1. The larger the value, the higher the degree to which the two stations share the transmission path.

[0075] The second item is the normalized electrical distance, which is determined by the ratio of the actual transfer impedance between the two stations to the reference impedance of the receiving-end power grid. The larger this value is, the weaker the electrical connection between the stations is, that is, the greater the degree of separation in terms of physical location or electrical connection.

[0076] The third item is the consistency of the power flow convergence direction, which is determined by whether the active power of the two stations flows into the same remaining channel and the proportion of the convergence duration to the total duration of the stage, with a value range of 0 to 1.

[0077] The fourth item is the consistency of voltage change transmission, which is determined by whether the direction of voltage change at the grid connection points of the two power stations is the same, whether the order of change is consistent, and the degree of overlap of the duration of change. The value range is from 0 to 1.

[0078] The fifth item is the reactive power support capacity, which is determined according to the voltage recovery of the grid connection point of another power station after the reactive power generation of one power station is increased, and the continuous relationship between the reactive power demand of the other power station and the voltage recovery. The value range is 0 to 1.

[0079] During the extraction of the above-mentioned features, information such as the station number, the start and end times of the status phase, the actual power transmission path, and the original operating status are retained to form a phased station electrical association feature table.

[0080] S2.2: For each pair of stations in each state phase, calculate the comprehensive coupling strength based on the electrical association characteristic quantity and classify the coupling category.

[0081] Based on the phased site electrical association characteristic table, the comprehensive coupling strength is calculated for the i-th and j-th sites within the s-th state phase. The comprehensive coupling strength is a quantitative basis for determining the coupling category of the two sites, and its calculation formula is as follows:

[0082]

[0083] in, This represents the combined coupling strength between the two stations in the s-th state stage, and is dimensionless. This indicates the proportion of shared outgoing paths, with a value ranging from 0 to 1; It represents the normalized electrical distance, is dimensionless, and the larger the value, the weaker the electrical connection between stations; This indicates the degree of consistency in the direction of the converging currents, and its value ranges from 0 to 1. It indicates the consistency of voltage change transmission, and its value ranges from 0 to 1; This indicates the degree of reactive power support, with a value ranging from 0 to 1; , , , These represent the shared path weight, electrical distance and power flow convergence weight, voltage and reactive power load weight, and shared path and reactive power load weight, respectively. Before normalization, each weight is set between 0.22 and 0.28, and normalization ensures that the sum of the four is 1. This value range ensures that structural connections and dynamic supports maintain similar contributions, avoiding a single feature directly determining the coupling category.

[0084] The above formula takes the actual shared channel as the basis for structural coupling, and uses an exponential decay term. This causes the power flow convergence contribution to decrease accordingly as the electrical distance increases, and then utilizes voltage transmission and reactive power transfer to reflect the dynamic coupling during faults; the product term of shared path and reactive power transfer... This is used to highlight the typical direct coupling state where a shared channel is used while simultaneously providing voltage support.

[0085] After the comprehensive coupling strength calculation is completed, the direct coupling judgment value is set to 0.46 to 0.50, and the weak association judgment value is set to 0.26 to 0.30. Station pairs with a comprehensive coupling strength not lower than the direct coupling judgment value are defined as directly coupled; those between the direct coupling judgment value and the weak association judgment value are defined as indirectly coupled; and those lower than the weak association judgment value are defined as weakly associated. The two judgment values ​​should be selected in conjunction with typical line disconnection tests: stations sharing remaining channels and having a clear reactive power transfer relationship correspond to a high-value range, i.e., near the direct coupling judgment value; stations that only have a limited impact through a common grid connection point correspond to a low-value range, i.e., near the weak association judgment value. The coupling categories and corresponding comprehensive coupling strengths of all station pairs in each stage are summarized to form a staged station coupling category and coupling strength table.

[0086] S2.3: Identify migration events between adjacent state stages for each station, including coupling category migration, path loss, and coupling category recovery. Record the corresponding migration nodes and their coupling categories before and after migration, as well as the migration time. At the same time, determine the main voltage support in each stage.

[0087] Based on the phased station coupling category and coupling strength table, migration events between adjacent state stages of each station are identified, including category migration caused by changes in coupling category, path loss caused by path loss, and category recovery caused by path recovery. The corresponding migration nodes, their coupling categories before migration, coupling categories after migration, and migration times are recorded. Specifically, if a station is transferred from an independent line to a remaining channel currently in use by another station, the migration of that station from indirect coupling or weak association to direct coupling is recorded; if a line disconnection causes a station to lose its original outgoing path, the path loss node is recorded; if automatic reclosing restores the original channel, the category recovery node is recorded.

[0088] While identifying migration nodes, the primary voltage support provider is determined for each stage. The voltage support contribution ratio of the i-th substation in the s-th stage is calculated using the following formula:

[0089]

[0090] in, This represents the voltage support contribution ratio of the i-th power station; and These represent the start and end times of the s-th stage, respectively. This represents the reactive power increment of the i-th power station relative to the start time of this phase, in megavars. Indicates the rated voltage of the common grid connection point; Indicates the actual voltage at the common grid connection point; m represents the number of power plants participating in reactive power support; r represents the serial number of the participating power plant; positive part calculation This means only the part within the parentheses that is greater than zero should be retained; The time decay coefficient, ranging from 0.95 to 1.05, gives a slightly higher weight to rapid reactive power support in the initial stage of a fault, while not excessively weakening the contribution of subsequent sustained support. The formula for calculating the voltage support contribution ratio above applies only to the actual voltage at the common grid connection point during the state phase. Below rated voltage Effective at a certain time. If within a certain period Never lower than In this phase, the primary voltage support provider is not specified, and the voltage support contribution ratio of all stations is determined. All values ​​are set to 0.

[0091] This formula calculates the actual increase in reactive power support provided by each power station during the period of voltage deficit, and applies attenuation weighting according to the time of support occurrence to distinguish between rapid main support and subsequent support. The numerator represents the weighted total effective reactive power support provided by a single power station within a phase, and the denominator represents the weighted total effective reactive power support provided by all participating power stations. The ratio of the two is the proportion of voltage support undertaken by that power station within this phase.

[0092] When a power station's voltage support contribution ratio reaches its maximum value and is not lower than 0.35, that power station is designated as the primary voltage support provider for that phase. If the voltage support contribution ratios of all power stations are lower than 0.35, multiple power stations with higher contribution ratios are retained as a common support group, and no individual primary support provider is designated. Migration node information, path loss node information, category recovery node information, and primary voltage support provider change information are summarized to form a table of changes in power station coupled migration nodes and support roles.

[0093] S2.4: According to the time sequence of the entire fault process, connect the coupling categories and migration times before and after migration at each migration node of each station in sequence to form the continuous migration chain.

[0094] Based on the table of changes in coupling migration nodes and supporting roles at the site, the coupling category before migration, the coupling category after migration, and the migration time at each migration node of each site are connected sequentially according to the time sequence of the entire fault process.

[0095] During the connection process, if the reclosing is successful and the original outgoing path is restored, the current category is connected to the corresponding category before the fault, indicating that the coupling relationship has been restored to the initial state; if the reclosing is successful but the power flow is still carried by the remaining channel, the category is not determined to be restored, and the current coupling category is maintained; if the reclosing fails or the circuit breaker trips again, the current coupling category is maintained and continues to extend backward, without any recovery connection.

[0096] Through the above connections, a continuous migration chain is ultimately formed, including the category migration direction, path loss nodes, major support change nodes, and category recovery nodes. This continuous migration chain fully depicts the evolution trajectory of the coupled categories at each site throughout the entire fault process, serving as the input for step S3 to perform phased reconstruction of the equivalent boundary of the entire site.

[0097] S3: Using the coupled category migration node in the continuous migration chain as the time of the iso-boundary reconstruction, perform phased reconstruction of the iso-boundary of the entire station and output the phased reconstruction result of the iso-boundary of the entire station.

[0098] S3.1: Using the coupling category migration node in the continuous migration chain as the time of equivalent boundary reconstruction, establish common coupling boundary, associated correction boundary and core tuning boundary according to the differences in the power station output path and voltage support role.

[0099] Based on the continuous migration chain of coupling categories of multiple stations, the coupling category migration node is used as the reconstruction time of the equivalent boundary. The coupling category before migration, coupling category after migration, actual transmission path, path loss status, main voltage support role and coupling category recovery status of each station are read in stages.

[0100] Based on the differences in the power station's transmission path and voltage support role, common coupling boundaries, correlation correction boundaries, and core setting boundaries are established. Specifically, for power stations that converge into the same remaining transmission channel, a common coupling boundary is established. These power stations share the same remaining channel in the topology and should be treated as a whole for equivalent processing. For power stations that still maintain independent transmission paths but receive voltage changes through a common grid connection point, a correlation correction boundary is established. Although these power stations do not share channels, their voltage responses still interact with other power stations through the common grid connection point and need to be corrected in the equivalent model. For power stations that may become the main voltage support provider, including cases where weakly correlated power stations become the main voltage support providers, a core setting boundary is established. These power stations undertake the main voltage support task during faults and should be included separately in the core setting scope.

[0101] If a station is connected to both the original outgoing path and the temporary receiving path during reclosing (i.e., the circuit breaker has closed but the power flow has not yet fully transferred to the original path), then the original path boundary and the temporary path boundary are established separately. In this case, the station is associated with both boundaries simultaneously, and its final assignment will be determined in subsequent sub-steps based on the degree of assignment, without directly restoring the fixed assignment before the fault. All the above boundaries are summarized according to the state stage, and each boundary includes a boundary number, the path it contains, the station, the coupling category, the supporting role, and the effective start and end times of the boundary, forming a staged equivalent boundary table.

[0102] S3.2: For a station that corresponds to only one boundary, its boundary affiliation is directly determined according to the current actual transmission path; for a station that is associated with multiple boundaries at the same time, an affiliation determination is performed to assign the station to the boundary whose affiliation is determined.

[0103] Based on the phased equivalent boundary table, the actual equivalent boundary to which each station belongs in the current phase is determined. For stations corresponding to only one boundary, their boundary affiliation is directly determined according to the current actual power transmission path, without additional calculation. For stations that are associated with multiple boundaries simultaneously during power transfer, bus paralleling, or reclosing recovery processes, an affiliation determination is performed to assign them to the boundary determined for affiliation.

[0104] First, a pre-judgment of the core support role is performed: when the voltage support contribution ratio of a certain station... If the value is not lower than 0.35, the station is directly included in the core setting boundary and will no longer participate in subsequent assignment calculations. This pre-judgment ensures that the main voltage support provider can be preferentially included in the core setting range, avoiding its incorrect inclusion in other boundaries due to complex path associations.

[0105] For other power stations simultaneously associated with multiple boundaries that have not triggered the aforementioned pre-judgment conditions, the degree of affiliation is calculated based on the proportion of shared transmission paths between the power station and the power stations within each boundary, the overall coupling strength, the consistency of voltage changes, and the proportion of voltage support contribution of the power station. In cases where a boundary contains multiple power stations, the proportion of shared transmission paths is taken as the average of the proportions of shared transmission paths between the power station and all power stations within the boundary; the overall coupling strength is taken as the average of the overall coupling strength between the power station and all power stations within the boundary; the consistency of voltage changes is the direct value of the consistency between the voltage change at the power station's grid connection point and the voltage change at the common grid connection point of the boundary; and the normalized electrical distance is the normalized electrical distance from the power station to the common convergence point of the boundary. The formula for calculating the degree of affiliation is as follows:

[0106]

[0107] in, It represents the degree of belonging of the i-th station to the g-th boundary within the s-th state stage, and is dimensionless; This indicates the proportion of the transmission route shared by this station and other stations within the boundary. When there are multiple stations within the boundary, this proportion is taken as the average value, and the value ranges from 0 to 1. This represents the average value of the overall coupling strength between the station and all stations within the boundary. When the boundary contains multiple stations, this average value is obtained by averaging the coupling strength of each station. It is dimensionless and is obtained by averaging the staged coupling strengths obtained in step S2.2. This represents the normalized electrical distance from the station to the boundary common convergence point; This indicates the degree of consistency between the voltage change of the power station and the common grid connection point at the boundary. When there are multiple power stations within the boundary, this value directly uses the degree of consistency between the power station and the common grid connection point, and the value range is from 0 to 1. This indicates the voltage support contribution ratio of the station obtained in step S2.3; , , , These are the structural path weight, coupling strength weight, voltage response weight, and support role weight. Before normalization, each weight is set between 0.22 and 0.28, and the sum of the four is normalized to 1. This value range ensures that the actual path assignment and the dynamic support assignment are close, preventing the site from being incorrectly included in the common coupling boundary simply because of its electrical proximity.

[0108] For the remaining stations that have not triggered the pre-judgment, they are preferentially assigned to the boundary with the highest degree of affiliation. When two boundaries have the same degree of affiliation, the boundary with the higher proportion of shared transmission paths is selected first; if they are still the same, the boundary with the smaller normalized electrical distance is selected. Stations with independent transmission paths are not merged with shared coupling boundaries; only associated correction boundaries are written.

[0109] For substations with weak associations that have already been written into the core setting boundary according to this rule, the association correction boundary will not be written again. The core of the above determination method is to use the actual transmission path as the basis for boundary assignment, and combine it with the coupling strength, voltage transmission relationship and support role identified in step S2 to determine a unique stage assignment for substations with multiple available paths. This solves the problem that the same substation may be associated with both the original path and the temporary path during line disconnection and reclosing, resulting in non-unique equivalent boundary assignments. The above assignment determination results are summarized to form the staged substation equivalent boundary division results.

[0110] S3.3: For common coupling boundaries, reconstruct the equivalent impedance according to the actual electrical relationship of parallel branches and series common paths, and retain the independent transfer impedance of the associated correction boundary to the convergence point of the common coupling boundary.

[0111] Based on the phased division of equivalent boundaries of the power stations, the capacity attribution and impedance composition of each equivalent boundary are reconstructed.

[0112] For common coupling boundaries, the available capacity of wind power, photovoltaic, energy storage, and dynamic reactive power compensation equipment operating in grid-connected mode within the boundary is summarized separately to form equivalent active power capacity, equivalent reactive power capacity, and equivalent capacity that can participate in support during faults. For associated correction boundaries, the independent capacity of the corresponding power stations is retained and not incorporated into the common coupling boundary. For core setting boundaries, the main voltage support capacity and its continuous support range are marked separately. Capacity is only attributed to boundaries with currently effective transmission paths; capacity that has lost its original transmission path and has not yet completed transfer should not be counted repeatedly.

[0113] For the impedance within the common coupling boundary, it is reconstructed according to the actual electrical relationship of parallel branches and series common path. The specific calculation formula is as follows:

[0114]

[0115] in, This represents the equivalent impedance of the g-th common coupling boundary in the s-th stage; This represents the common path impedance between the convergence of branch lines from each station and the common grid connection point. Indicates the number of stations within the common coupling boundary; This indicates whether the i-th station has a valid outgoing connection in this stage; 1 indicates a connection and 0 indicates otherwise. This represents the equivalent impedance of the station equipment group, in ohms. Indicates the impedance of the station transformer; This represents the impedance of the branch line converging at the station. All impedances are converted to the same voltage reference before being included in the calculation.

[0116] The formula first groups the equipment groups, transformers, and independent collection lines of each station into series branches, then connects multiple station branches with effective connections in parallel for equivalent values, and finally connects the common remaining channel that actually supplies power after a series fault, which conforms to the actual electrical connection relationship. The impedance of the associated correction boundary does not participate in the above parallel connection, but retains its independent transfer impedance to the common coupling boundary convergence point. The above capacity and impedance reconstruction results are summarized, while retaining the boundary category, station affiliation, and stage validity time determined in S3.2, as input for the subsequent S3.4.

[0117] S3.4: Trace the active power flow path, trace the reactive power support path in reverse, determine the time center of gravity of reactive power support of each station as the equivalent response time, determine the support commissioning order according to the equivalent response time, and write it together with the topology switching order in the continuous migration chain into the control succession relationship table.

[0118] Based on the obtained reconstruction results, the active power flow path is traced. Starting from the equivalent unit of each substation, the active power flow is traced along the currently operational busbars, main transformers, and transmission lines to the common grid connection point, forming a power flow carrying path that sequentially connects the equivalent unit of the substation, the common coupling boundary, the remaining transmission channels, and the common grid connection point. This path reflects the actual electrical path through which active power is transmitted from each substation to the common grid connection point.

[0119] After power flow path tracing is completed, the reactive power support path is traced in reverse. Based on the location of reactive power output increase, voltage deficit location, and the direction of voltage change at the common grid connection point, the electrical path from the main voltage support provider to the supported boundary is traced in reverse. For cases where multiple substations provide reactive power support sequentially, the combined effect of reactive power increment and voltage deficit at each moment is used as the weight to perform a weighted average over the entire stage, determining the temporal center of gravity of reactive power support at each substation as the equivalent response time. This time reflects the temporal center of gravity of the substation's actual voltage support function in this stage, rather than simply using the issuance time of the first control command, thus more accurately depicting the actual participation sequence of the substation during the support process.

[0120] The support activation sequence is determined based on the equivalent response time. Fast support units, continuous support units, and subsequent backup support units are activated sequentially according to their equivalent response times, arranged from smallest to largest. This sequence, along with the topology switching sequence in the continuous migration chain (including protection clearing, remaining channel replacement, and reclosing operation sequence), is written into the control succession relationship table. This output is also associated with equivalent capacity, equivalent impedance, and boundary assignment for reference in subsequent sub-step S3.5.

[0121] S3.5: According to the time sequence of the continuous migration chain, connect the common coupling boundary, the associated correction boundary and the core tuning boundary of each stage in sequence, and attach reconstruction parameters to each boundary. Together with the control acceptance relationship table, output the reconstruction result of the phased full-site equivalent boundary.

[0122] After completing the boundary delineation, attribution determination, and parameter reconstruction, the common coupling boundary, associated correction boundary, and core tuning boundary of each stage are sequentially connected according to the time sequence of the continuous migration chain. Reconstruction parameters are attached to each boundary, including equivalent capacity attribution, equivalent impedance composition, power flow receiving path, voltage support path, control action sequence, and effective start and end times. Together with the control receiving relationship table, the phased full-site equivalent boundary reconstruction results are output.

[0123] During the connection process, after the line is disconnected, all stations will use the reconfiguration boundary according to the remaining outgoing structure, and the boundary division before the fault will no longer be used; when the automatic reclosing is successful but the original power flow path has not yet been restored, the temporary boundary will continue to be maintained until the original outgoing path resumes to bear the corresponding power flow and the station coupling category is restored, at which point the temporary boundary will be terminated and the recovery phase boundary will be established.

[0124] Through the above connections, the final output is a reconstruction result that can represent the changes in the equivalent attribution of all stations in stages. This result serves as the input for step S4 to carry out cross-stage collaborative parameter tuning.

[0125] S4: Based on the phased full-site equivalent boundary reconstruction results, conduct cross-stage collaborative parameter tuning to form a cross-stage collaborative parameter set corresponding to each stage of the continuous migration chain.

[0126] S4.1: Read the detailed information of each boundary one by one according to each state stage. Each boundary corresponds to each equivalent unit. Determine the basic parameters of each equivalent unit, including the equivalent impedance.

[0127] Based on the phased full-site equivalent boundary reconstruction results output in step S3, detailed information of common coupling boundary, associated correction boundary and core setting boundary is read one by one according to the normal transmission stage before the fault, the fault clearing stage, the stage of concentrated carrying of remaining channels, the automatic reclosing stage and the recovery stage after reclosing. Each boundary corresponds to each equivalent unit.

[0128] Determine the basic parameters of each equivalent unit, including the equivalent impedance. For the equivalent impedance, the common coupling boundary is directly referenced from the reconstruction obtained in step S3 according to the branch parallel and common path series configuration. The associated correction boundary retains its independent transfer impedance to the convergence point of the common coupling boundary; the core setting boundary uses its output impedance. Specifically, the available capacity of all wind power, photovoltaic, energy storage, and dynamic reactive power compensation equipment in grid-connected operation within the boundary is summarized to form the active power equivalent capacity and reactive power equivalent capacity.

[0129] For the associated correction boundary, the independent capacity of the stations within this boundary and the transfer impedance to the common convergence point are retained, and they are not incorporated into the equivalent parameters of the common coupling boundary. For the core setting boundary, the available capacity, outgoing impedance, and support duration of the main voltage support equipment are registered separately.

[0130] The basic parameters of each boundary are summarized, while the boundary category, power flow path and stage validity time are retained as the basis for subsequent S4.2 calculations.

[0131] S4.2: Determine the remaining reactive power support capacity and support deployment sequence of each equivalent unit. After the preceding equivalent unit reaches the remaining reactive power support boundary, the subsequent equivalent unit shall take over. When multiple stations converge into the same remaining channel, they shall be uniformly constrained by the carrying capacity of the common channel.

[0132] Based on the obtained boundary parameters, the remaining reactive power support capacity of each equivalent unit is determined, and the support sequence is determined accordingly.

[0133] The calculation of remaining reactive power support capacity requires comprehensive consideration of the apparent capacity limit of each device under current voltage and current constraints, current active power output, and current reactive power output. The specific calculation formula is as follows:

[0134]

[0135] in, This represents the remaining reactive power support capacity of the equivalent unit, in megavars. Indicates the number of stations within the common coupling boundary; This indicates whether the i-th station has a valid outgoing connection in this stage; 1 indicates a connection and 0 indicates otherwise. This represents the apparent capacity limit of all grid-connected equipment in the i-th substation under the combined constraints of terminal voltage and allowable current at the current stage, expressed in megavolt-amperes (MVA). This value is obtained by multiplying the allowable current of each device by the current terminal voltage and then summing the results. This indicates the current active power output of the equipment, measured in megawatts (MW). This indicates the current reactive power output of the equipment, measured in megavars. Reactive power injected into the grid is positively evaluated; positive part calculation. This indicates that the result is zero when it is less than zero. This formula is applicable when the absolute value of the equipment's active power output does not exceed the current apparent capacity limit.

[0136] Within the constraints of equipment capacity, this formula determines the remaining reactive power support capacity of each equivalent unit by subtracting the current active and reactive power occupancy from the apparent capacity limit of each device. For dynamic reactive power compensation equipment, its active power output is taken as zero, and the apparent capacity limit is the currently available reactive power capacity.

[0137] The order of support deployment is determined according to the equivalent response time: in the initial stage of a fault, the equivalent unit with the earliest equivalent response time undertakes rapid support; after the preceding equivalent unit reaches the remaining reactive power support boundary, the subsequent equivalent units take over continuous support; when a previously weakly correlated power station becomes the main voltage support provider, its remaining reactive power support capacity is written into the core support parameters, no longer merely as a background correction item; when multiple power stations converge into the same remaining channel, they are uniformly constrained by the common channel's carrying capacity, and it is not allowed to repeatedly configure support capacity according to the original sending channel. The above setting method ensures that the reactive power support capacity changes together with active power occupancy, equipment current limiting status, and the support role of the power station, avoiding the continued use of pre-fault reactive power parameters during the concentrated carrying phase of the remaining channel.

[0138] The remaining reactive power support capacity and support sequence of each equivalent unit in each stage are summarized and used as input for the subsequent S4.3.

[0139] S4.3: For topology-altering parameters, switch them immediately according to the actual position of the circuit breaker. For continuous parameters that need to be gradually withdrawn as the power flow recovers after successful reclosing, perform a gradual conversion and determine the conversion relationship between parameter groups.

[0140] Based on the obtained supporting parameters, parameter transformation relationships between adjacent state stages are established. Precedence parameters, target parameters, transition trigger states, and exit conditions are set for adjacent stages respectively.

[0141] For topology-altering parameters, their changes are determined by the actual location of the circuit breaker and are not continuously interpolated. When a power station changes from indirect coupling to direct coupling, the common channel equivalent impedance, common capacity attribution, and common support sequence are activated at the moment when the remaining channel actually receives power flow. When a previously weakly coupled power station becomes the main voltage support provider, the core support parameters are activated at the moment when its reactive power output begins to bear the voltage deficit at the common grid connection point. Changes in structural parameters caused by protection disconnection or transmission path disconnection are switched immediately according to the actual location of the circuit breaker and are not continuously interpolated.

[0142] For continuous parameters that need to be gradually phased out as power flow recovers after successful reclosing, including effective active power participation capacity, reactive power support capacity, and active power response time, a gradual transformation is performed on these continuous parameters. Specifically, the following formula is used to complete the continuous transformation:

[0143]

[0144] in, This represents the current value of the r-th continuous parameter during the transformation process; This indicates temporary parameters used at the start of the conversion; This indicates the target parameter used after the power flow is restored; the same formula is only used to convert parameters with the same dimensions, so the output dimensions are consistent with the corresponding parameters. Indicates the start time of parameter conversion; The duration corresponding to the actual power flow completing the transfer from the temporary channel to the recovery channel is determined by the start and end times of the recovery phase in step S3; This represents the dimensionless transformation morphology coefficient, ranging from 0.95 to 1.05. This value range ensures that the parameter transformation remains continuous and closely approximates the actual power flow recovery rate, preventing abrupt jumps in the initial transformation phase or the prolonged retention of temporary parameters at the end of the recovery phase.

[0145] This formula uses the actual power flow recovery period as the parameter transition interval, allowing temporary control parameters to continuously transition from the current stage value to the recovery stage value. It is important to note that structural parameters such as equivalent resistance, equivalent reactance, circuit breaker connection status, and station physical capacity are still switched in real-time according to the actual topology and are not smoothed using this formula. The support connection sequence is discrete and switches as the main support changes; similarly, it is not continuously converted using this formula. The above processing method distinguishes between topology abrupt change parameters and control gradual change parameters to prevent all parameters from simultaneously returning to their pre-fault values ​​after the reclosing operation.

[0146] Summarize the above conversion relationships between adjacent stages to determine the conversion relationships between parameter groups.

[0147] S4.4: According to the time sequence of the entire fault process, establish a parameter group for each stage based on the transformation relationship, including the activation conditions and all tuning parameters, to form a cross-stage collaborative parameter group corresponding to each stage of the continuous migration chain.

[0148] Based on the conversion relationship between the obtained parameter groups, parameter groups are established for each stage according to the time sequence of the entire fault process, including the activation conditions and all setting parameters.

[0149] After a fault is cleared, the remaining channel parameter group is activated; after an indirectly coupled station is converted to a directly coupled station, the common channel parameter group is activated; after a previously weakly coupled station becomes the primary support station, the core support parameter group is activated; when reclosing is successful but power flow has not yet been restored, the temporary parameter group is maintained and gradually phased out according to the conversion relationship in S4.3; when reclosing fails or trips again, the recovery conversion is canceled and the remaining channel parameter group is maintained. Each parameter group contains all the setting parameters extracted from the current equivalent boundary division results, covering dimensions such as equivalent capacity, equivalent impedance, active power response characteristics, reactive power support capability, and support sequence.

[0150] Through the above settings, a cross-stage collaborative parameter set is finally formed, which corresponds to the continuous migration chain of multiple station coupling categories stage by stage, and serves as the input for step S5 to construct the equivalent model of new energy stations.

[0151] S5: Based on the cross-stage collaborative parameter group, construct an equivalent model of new energy power stations in multi-infeed weak grids. The equivalent model calls the corresponding parameter group according to the currently activated state stage, and maintains or updates the model state when reclosing anomalies and coupling categories migrate again, and outputs all model parameters and state information.

[0152] S5.1: Configure enable conditions, maintain conditions and exit conditions for parameter groups in each state stage. Only one parameter group or one transformation relationship is allowed to be active at any given time. The active transformation relationship calculates the current call value in real time to form a collaborative parameter activation sequence for the entire fault process.

[0153] Based on the coupled migration-driven cross-stage collaborative parameter group output in step S4, enable, maintain, and exit conditions are configured for the parameter group in each state stage. Only one parameter group or one transformation relationship is allowed to be active at any given time.

[0154] For parameters that need to continuously change with the power flow, the parameters are called according to the current state stage. If the current stage is stable, meaning the topology and operation mode no longer change, the parameter values ​​corresponding to that stage are directly called. If the current stage is in a transition process between adjacent stages and the transition process is activated, the current call value is calculated in real time according to the continuous transition relationship given in sub-step S4.3. This transition relationship is based on the transition start time, the actual power flow carrying duration, and the transition morphology coefficient, and undergoes exponential gradual change to ensure that the control parameters smoothly transition from the current stage value to the next stage value.

[0155] Structural parameters such as equivalent resistance, equivalent reactance, circuit breaker status, and physical connection capacity only use values ​​called during the stable phase and are switched instantly during topology operations, without participating in the aforementioned continuous conversions. This calling relationship setting ensures that model parameter calls are determined by the actual line and power flow conditions, preventing premature restoration of pre-fault parameters simply due to reclosing operations. The calling rules for parameter groups at each stage are summarized to form a coordinated parameter activation sequence for the entire fault process.

[0156] S5.2: Construct an equivalent model, establish corresponding equivalent units according to the current active boundary, with each boundary corresponding to an equivalent unit, and write tuning parameters to each equivalent unit. Calculate the internal port voltage of each equivalent unit based on the equivalent impedance, perform power constraints within the capacity range, and sequentially deploy each support unit according to the support deployment order.

[0157] Based on the obtained activation sequence of collaborative parameters throughout the fault process, a phased equivalent model of the new energy power station is constructed. Corresponding equivalent units are established according to the currently activated common coupling boundary, associated correction boundary and core setting boundary. Each boundary corresponds to an equivalent unit, and setting parameters are written to each equivalent unit, including equivalent capacity, equivalent impedance, active response time, remaining reactive power support capacity, control action time difference and support connection sequence.

[0158] Stations within the common coupling boundary share a common channel impedance and unified capacity allocation, and all stations participate in the calculation as a single equivalent unit. The associated correction boundary maintains independent power injection and is not incorporated into the common coupling boundary; it acts on the common grid connection point through impedance transfer. The core setting boundary prioritizes the use of primary voltage support capabilities according to the support order; when the system voltage drops, support resources within this boundary are deployed first.

[0159] The internal port voltage of each equivalent unit is calculated based on the equivalent parameters. Each equivalent unit is connected to its power output, equivalent impedance, and common grid connection point voltage using the following formula:

[0160]

[0161] in, This represents the phase voltage at the port inside the g-th equivalent unit; Indicates the phase voltage at the common grid connection point; This indicates the equivalent impedance invoked in the current stage; and These represent the single-phase active power and single-phase reactive power of the equivalent unit, respectively, in watts and volt-amperes (V / var). The total three-phase power is divided by 3 and substituted into the equation. 'j' represents the imaginary unit. The superscript asterisk indicates conjugate operation. In this formula, the power-to-voltage ratio, after conjugate operation, represents the equivalent injected current. The product of the equivalent impedance and the injected current represents the voltage drop across the output path. The voltage at the common grid connection point plus this voltage drop equals the actual voltage at the internal port of the equivalent unit. Therefore, both sides of the formula are in voltage dimensions.

[0162] The model generates the active power change process according to the active power response time and restricts the co-occupancy of active and reactive power within the equivalent capacity range. Rapid support, continuous support, and subsequent support units are deployed sequentially according to the control action time difference. When the preceding unit reaches the remaining reactive power support boundary, the next support unit is called, ensuring that each support unit is deployed in an orderly manner according to the set sequence.

[0163] S5.3: Perform appropriate maintenance or update processing on the model state under abnormal scenarios.

[0164] Based on the constructed phased equivalent model of new energy power stations, special processing is carried out on possible reclosing anomalies and coupling category migration during operation.

[0165] When reclosing fails, the model maintains the current parameter state for the remaining channels and does not perform any recovery operations. When reclosing succeeds and the circuit breaker trips again, the model immediately terminates the conversion and reactivates the temporary parameter group. When the circuit breaker has closed but the original channel has not yet taken over the corresponding substation power flow, the model continues to maintain the current reconfiguration boundary and does not restore the capacity assignment before the fault, avoiding the problem of premature rollback of the equivalent boundary in scenarios where the switch is restored but the power flow has not been restored.

[0166] If the power station experiences a new coupling category migration due to re-supply, busbar reconfiguration, or a change in the main support provider, the boundaries are redefined starting from the current model state, and the activation order of subsequent parameters is updated. This approach allows the model to cyclically adapt to changes in coupling relationships under continuous disturbance scenarios until the entire fault process ends. The model states after the above anomaly handling are summarized to form an equivalent model sequence of anomaly state maintenance and re-migration.

[0167] S5.4: Perform a consistency check on the model results. After the consistency check passes, output all model parameters and status information in chronological order.

[0168] Based on the obtained equivalent model sequence after maintaining and re-migrating from the abnormal state, a consistency check is performed on the model results. For each station, it is checked whether it belongs to only one capacity boundary at any given time to prevent duplicate or missing capacity assignments. For each state stage, it is checked whether the effective transmission path is consistent with the current equivalent impedance to confirm that there are no contradictions between the electrical connection relationship and the impedance parameters. At the same time, it is confirmed that the support sequence is updated synchronously after the main voltage support provider changes to ensure that the order of calling support resources is consistent with the actual change of support role.

[0169] After the consistency check is passed, all parameters and status information of the model are output in chronological order, including the station coupling category, equivalent boundary, station affiliation, equivalent capacity, equivalent impedance, active power response, reactive power support capability, control action time difference, support connection sequence, parameter activation time, temporary parameter holding interval, and recovery parameter exit process for each state stage.

[0170] Through the above processing, a continuous equivalent model result is finally formed from line fault, protection isolation, remaining channel takeover, automatic reclosing to power flow restoration or re-fault. This result fully covers the equivalent parameters of multiple power stations at each stage of the fault process and completes the coordinated tuning of equivalent parameters of multiple feeder weak grid new energy power stations.

[0171] According to embodiments of this disclosure, an electronic device is also provided, which may include a processor, a communications interface, a memory, and a communication bus, wherein the processor, the communications interface, and the memory communicate with each other via the communication bus. The processor can invoke logical instructions stored in the memory to execute the methods provided in the above embodiments.

[0172] Furthermore, when the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, they can be stored in a non-transitory computer-readable storage medium. Based on this understanding, the technical solution of this disclosure, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this disclosure. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0173] On the other hand, this disclosure also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the methods provided in the above embodiments.

Claims

1. A method for coordinated tuning of equivalent parameters of new energy power plants in multi-infeed weak power grids, characterized in that, The method includes: S1. Establish a joint state sequence of topology and operation for multiple sites throughout the entire fault process. The joint state sequence of topology and operation includes topology information and operation status information covering each state stage from before the fault to after the fault recovery. The event type and transition time that trigger the state transition are marked between adjacent stages. S2. Based on the multi-site topology and joint operation state sequence of the entire fault process, identify the continuous migration process of the site coupling category, and form a continuous migration chain including coupling category migration nodes, path loss nodes, main support change nodes and coupling category recovery nodes. The coupling categories include direct coupling, indirect coupling and weak association. S3. Using the coupled category migration nodes in the continuous migration chain as the time of the equivalent boundary reconstruction, perform phased reconstruction of the equivalent boundary of the entire station and output the phased reconstruction result of the equivalent boundary of the entire station. S4. Based on the phased full-site equivalent boundary reconstruction results, conduct cross-stage collaborative parameter tuning to form a cross-stage collaborative parameter set corresponding to each stage of the continuous migration chain. S5. Based on the cross-stage collaborative parameter group, construct an equivalent model of new energy power stations in multi-infeed weak grids. The equivalent model calls the corresponding parameter group according to the currently activated state stage, and maintains or updates the model state when there is a reclosing anomaly or the coupling category migrates again, and outputs all model parameters and state information.

2. The method according to claim 1, characterized in that, S1 includes: S1.1 Obtain the electrical basic parameters of each new energy power station and the fault response records during the fault period; S1.2 Based on the electrical basic parameters and fault response records, the occurrence of line faults, protection disconnection, start of remaining channel takeover, automatic reclosing initiation, successful reclosing and failed reclosing are taken as forced state boundaries. When all state boundaries are determined, the corresponding state boundary markers are added to the records at that moment. S1.

3. Based on the adjacent state boundaries, the system is divided into the following stages: pre-fault stage, fault occurrence stage, protection clearance stage, remaining channel takeover stage, automatic reclosing stage, and fault recovery stage after successful reclosing or continuous fault stage after failed reclosing. When reclosing is successful, the system proceeds to the fault recovery stage; when reclosing fails, the system proceeds to the continuous fault stage. Within each stage, the system tracks the actual transmission path from each station to the common grid connection point and registers the topology and operating status information within that stage. S1.4 Connect each stage sequentially according to the time sequence of state occurrence, and mark the event type that triggers the state transition between adjacent stages to form the multi-site topology and operation joint state sequence.

3. The method according to claim 1, characterized in that, S2 includes: S2.1 According to each state stage in the joint state sequence of topology and operation, track the actual electrical connection path between each station and the common grid connection point, and extract electrical correlation feature quantities to characterize the structural connection and dynamic support relationship between stations. The electrical correlation feature quantities include the proportion of shared transmission paths, normalized electrical distance, consistency of power flow convergence direction, consistency of voltage change transmission, and reactive power support acceptance. S2.2 For each pair of stations in each state stage, calculate the comprehensive coupling strength based on the electrical association characteristic quantity, and classify each pair of stations into coupling categories of direct coupling, indirect coupling, or weak association. S2.3 Identify migration events between adjacent state stages for each station, including coupling category migration, path loss, and coupling category recovery. Record the corresponding migration nodes and their coupling categories before and after migration, as well as the migration time. At the same time, determine the main voltage support in each stage. S2.

4. According to the time sequence of the entire fault process, connect the coupling categories and migration times before and after migration at each migration node of each station in sequence to form the continuous migration chain.

4. The method according to claim 1, characterized in that, S3 includes: S3.

1. Using the coupling category migration node in the continuous migration chain as the time of equivalent boundary reconstruction, establish common coupling boundary, associated correction boundary and core tuning boundary according to the differences in the power station output path and voltage support role; S3.2 For a station that corresponds to only one boundary, its boundary affiliation is directly determined according to the current actual transmission path; for a station that is associated with multiple boundaries at the same time, an affiliation determination is performed to assign the station to the boundary whose affiliation is determined. S3.3 For common coupling boundaries, the equivalent impedance is reconstructed according to the actual electrical relationship of parallel branches and series common paths, and the impedance of the associated correction boundary retains its independent transfer impedance to the convergence point of the common coupling boundary. S3.

4. Trace the active power flow path, reverse the reactive power support path, determine the time center of gravity of reactive power support of each station as the equivalent response time, determine the support input order according to the equivalent response time, and write it together with the topology switching order in the continuous migration chain into the control acceptance relationship table. S3.

5. According to the time sequence of the continuous migration chain, connect the common coupling boundary, the associated correction boundary and the core tuning boundary of each stage in sequence, and attach reconstruction parameters to each boundary. Together with the control acceptance relationship table, output the reconstruction result of the phased full-site equivalent boundary.

5. The method according to claim 4, characterized in that, The attribution determination includes: When the voltage support contribution ratio of the station is not lower than the set threshold, it is directly included in the core setting boundary; Otherwise, the degree of affiliation is calculated based on the proportion of shared transmission paths between the station and other stations within the boundary, the overall coupling strength, the consistency of voltage changes, and the proportion of voltage support contribution of the station, and it is assigned to the boundary with the highest degree of affiliation.

6. The method according to claim 1, characterized in that, S4 includes: S4.1 Read the detailed information of each boundary one by one according to each state stage. Each boundary corresponds to each equivalent unit. Determine the basic parameters of each equivalent unit, including the equivalent impedance. S4.2 Determine the remaining reactive power support capacity and support deployment sequence of each equivalent unit. After the preceding equivalent unit reaches the remaining reactive power support boundary, the subsequent equivalent unit shall take over. When multiple stations converge into the same remaining channel, they shall be uniformly constrained by the carrying capacity of the common channel. S4.3 For topology-altering parameters, switch them immediately according to the actual position of the circuit breaker. For continuous parameters that need to be gradually withdrawn as the power flow recovers after successful reclosing, perform a gradual conversion and determine the conversion relationship between parameter groups. S4.

4. According to the time sequence of the entire fault process, establish a parameter group for each stage based on the transformation relationship, including the activation conditions and all tuning parameters, to form a cross-stage collaborative parameter group corresponding to each stage of the continuous migration chain.

7. The method according to claim 1, characterized in that, S5 includes: S5.1 Configure the activation conditions, maintenance conditions and exit conditions for the parameter groups in each state stage. Only one parameter group or one transformation relationship is allowed to be active at the same time. The active transformation relationship calculates the current call value in real time to form a collaborative parameter activation sequence for the entire fault process. S5.2 Construct an equivalent model, establish corresponding equivalent units according to the current active boundary, one equivalent unit for each boundary, write tuning parameters to each equivalent unit, calculate the internal port voltage of each equivalent unit based on the equivalent impedance, perform power constraints within the capacity range, and put each support unit into the support unit in sequence according to the support input order; S5.

3. Perform appropriate maintenance or update processing on the model state under abnormal scenarios; S5.4 Perform a consistency check on the model results. After the consistency check passes, output all model parameters and status information in chronological order.

8. The method according to claim 7, characterized in that, The process of maintaining or updating the model state under abnormal scenarios includes: When reclosing fails, the current parameter status of the remaining channels is maintained; When the circuit breaker trips again after a successful reclosing, the switching is terminated and the temporary parameter group is reactivated. When the circuit breaker has been closed but the original channel has not yet received power flow, maintain the current reconfiguration boundary; When a new coupling category migration occurs at the site, the boundaries are redefined and the activation order of subsequent parameters is updated, starting from the current model state.

9. An electronic device, characterized in that, The electronic device includes a memory and at least one processor, the memory storing a computer program, and the processor executing the computer program to implement the method of any one of claims 1-8.

10. A non-transitory computer-readable storage medium, characterized in that, It stores a computer program, which, when executed, performs the method according to any one of claims 1-8.

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