Power frequency overvoltage analysis method and device considering negative sequence current control

Abstract

The invention provides a power frequency overvoltage analysis method and device considering negative sequence current control, and relates to the technical field of electronic power, and the method comprises the steps: constructing a sequence voltage balance model at a non-full-phase fault based on obtained circuit information; combining the sequence voltage balance model with a three-phase boundary condition of a non-full-phase fault to construct a sequence current model at the fault; solving positive and negative sequence components of the terminal voltage by using the sequence current model and adopting a sequence-dividing loop iteration algorithm; and generating the power frequency overvoltage at the fault according to the positive and negative sequence components of the generator terminal voltage and the obtained positive and negative sequence components of the generator terminal output current. According to the power frequency overvoltage analysis method and device considering negative sequence current control provided by the invention, the influence rule of positive and negative sequence output of a new energy unit on the power frequency overvoltage level of a fault point is accurately evaluated during the non-full-phase operation period of a new energy collection system, and a theoretical basis is provided for making a control strategy.

Description

Technical Field

[0001] This application relates to the field of electronic power technology, and in particular to a power frequency overvoltage analysis method and apparatus that takes into account negative sequence current control. Background Technology

[0002] The transmission of new energy sources such as wind and solar power across regions via ultra-high voltage (UHV) AC transmission networks has become a key technical feature of new power systems. However, the large-scale integration of new energy sources and their power electronic equipment has resulted in a "double high" characteristic in the power grid: high penetration rate and a high proportion of power electronic equipment. As a result, the electrical connection between the new energy aggregation bus and the main grid is weak, and the system lacks sufficient synchronous power supply support, exhibiting typical characteristics of a weak power grid.

[0003] Recent simulations and field tests have shown that after a single-phase transient fault occurs in a renewable energy collection system, during the period of non-full-phase operation, a power frequency overvoltage phenomenon may occur, causing a voltage rise in one phase. This type of overvoltage not only limits the transmission capacity of renewable energy but also poses a threat to the safe and stable operation of the power grid, necessitating research into its mechanisms and suppression.

[0004] Current technical solutions typically lack negative-sequence current control capabilities for traditional generator sets, leading to uncontrollable negative-sequence output under asymmetrical fault conditions. This makes it difficult to accurately model negative-sequence sources on the generator side in the sequence network model. Therefore, existing methods struggle to effectively analyze the impact of generator output on power frequency overvoltages during non-full-phase operation. Furthermore, current fault ride-through standards only specify negative-sequence current support strategies for renewable energy power plants under asymmetrical grounding faults, lacking systematic research on the positive and negative-sequence output characteristics of renewable energy units under the special condition of non-full-phase operation. This also fails to establish a basis for developing corresponding control strategies, making it difficult to meet the safety analysis and control optimization needs of current high-proportion renewable energy grid-connected scenarios. Summary of the Invention

[0005] To address the problems in the prior art, this application provides a power frequency overvoltage analysis method and apparatus that takes into account negative sequence current control, which can solve the problems existing in the prior art.

[0006] In a first aspect, this application provides a power frequency overvoltage analysis method that takes into account negative sequence current control, including:

[0007] A sequence voltage balance model at the non-full-phase fault location is constructed based on the acquired circuit information;

[0008] By combining the sequence voltage balance model with the three-phase boundary conditions of a non-full-phase fault, a sequence current model at the fault location is constructed.

[0009] The positive and negative sequence components of the terminal voltage are solved using the sequence current model and a sequential cyclic iterative algorithm.

[0010] The power frequency overvoltage at the fault location is generated based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0011] Furthermore, the construction of the sequence voltage balance model at the non-full-phase fault based on the acquired circuit information includes:

[0012] Based on the circuit information, a sequence network model is established after a non-full-phase fault; the sequence network model includes a positive sequence network model, a negative sequence network model, and a zero sequence network model.

[0013] The ordered voltage balance model is constructed based on the ordered network model.

[0014] Furthermore, the step of combining the sequence voltage balance model with the three-phase boundary conditions of a non-full-phase fault to construct a sequence current model at the fault location includes:

[0015] The three-phase boundary conditions of the non-full-phase fault are determined based on the circuit information.

[0016] The three-phase boundary conditions are converted into sequence component boundary conditions;

[0017] The sequence current model is constructed based on the sequence voltage balance model and the sequence component boundary conditions.

[0018] Furthermore, the step of using the sequence current model to solve for the positive and negative sequence components of the terminal voltage using a sequential cyclic iterative algorithm includes:

[0019] The sequence current model is simplified and the initial value of the positive sequence component of the terminal voltage is set.

[0020] Using the simplified sequence current model and the initial value of the positive sequence component of the terminal voltage, the positive and negative sequence components of the terminal voltage are solved by a sequential cyclic iterative algorithm.

[0021] Furthermore, the step of using the simplified sequence current model and the initial value of the positive sequence component of the terminal voltage to solve for the positive and negative sequence components of the terminal voltage using a sequential iterative algorithm includes:

[0022] The negative sequence component of the machine terminal output current is set to a preset negative sequence current reference value, and the negative sequence component of the machine terminal voltage is calculated by combining the simplified sequence current model and the positive sequence component of the machine terminal voltage.

[0023] The positive sequence component of the generator terminal output current is set to a preset positive sequence current reference value, and the positive sequence component of the generator terminal voltage is calculated by combining the simplified sequence current model, the negative sequence component of the generator terminal voltage, and the preset positive sequence output constraint model.

[0024] The above operations are performed iteratively until the positive sequence component of the terminal voltage converges, thus obtaining the positive and negative sequence components of the terminal voltage.

[0025] Further, the step of generating the power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current includes:

[0026] The positive and negative zero sequence components of the machine-side voltage at the fault location are calculated based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0027] The positive and negative zero-sequence components of the machine-side voltage at the fault location are subjected to symmetrical component inverse transformation to obtain the power frequency overvoltage at the fault location.

[0028] Secondly, this application provides a power frequency overvoltage analysis device that takes into account negative sequence current control, comprising:

[0029] The sequence voltage balance model construction unit is used to construct a sequence voltage balance model at the non-full-phase fault location based on the acquired circuit information.

[0030] The sequence current model construction unit is used to combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location.

[0031] Terminal voltage solution unit is used to solve for the positive and negative sequence components of the terminal voltage using the sequence current model and a sequential cyclic iterative algorithm.

[0032] The power frequency overvoltage generation unit is used to generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the acquired terminal output current.

[0033] Furthermore, the sequence voltage balance model construction unit includes:

[0034] The sequence network model building module is used to build a sequence network model after a non-full-phase fault based on the circuit information; the sequence network model includes a positive sequence network model, a negative sequence network model, and a zero sequence network model.

[0035] The sequence voltage balance model construction module is used to construct the sequence voltage balance model based on the sequence network model.

[0036] Furthermore, the sequence current model construction unit includes:

[0037] The three-phase boundary condition determination module is used to determine the three-phase boundary conditions of the non-full-phase fault based on the circuit information.

[0038] The sequence component boundary condition determination module is used to convert the three-phase boundary conditions into sequence component boundary conditions.

[0039] The sequence current model construction module is used to construct the sequence current model based on the sequence voltage balance model and the sequence component boundary conditions.

[0040] Furthermore, the terminal voltage calculation unit includes:

[0041] The sequence current model simplification module is used to simplify the sequence current model and set the initial value of the positive sequence component of the terminal voltage.

[0042] The terminal voltage solution module is used to solve for the positive and negative sequence components of the terminal voltage using a simplified sequence current model and the initial value of the positive sequence component of the terminal voltage, employing a sequential cyclic iterative algorithm.

[0043] Furthermore, the terminal voltage calculation module includes:

[0044] The negative sequence component calculation submodule is used to set the negative sequence component of the terminal output current to a preset negative sequence current reference value, and calculate the negative sequence component of the terminal voltage by combining the simplified sequence current model and the positive sequence component of the terminal voltage.

[0045] The positive sequence component calculation submodule is used to set the positive sequence component of the terminal output current to a preset positive sequence current reference value, and calculate the positive sequence component of the terminal voltage by combining the simplified sequence current model, the negative sequence component of the terminal voltage, and the preset positive sequence output constraint model.

[0046] The iterative operation submodule is used to iteratively execute the above operations until the positive sequence component of the terminal voltage converges, thereby obtaining the positive and negative sequence components of the terminal voltage.

[0047] Furthermore, the power frequency overvoltage generation unit includes:

[0048] The fault location machine-side voltage calculation module is used to calculate the positive and negative zero sequence components of the fault location machine-side voltage based on the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the acquired terminal output current.

[0049] The power frequency overvoltage generation module is used to perform symmetrical component inverse transformation on the positive and negative zero sequence components of the machine-side voltage at the fault location to obtain the power frequency overvoltage at the fault location.

[0050] This application provides a power frequency overvoltage analysis method and apparatus that considers negative sequence current control. It constructs a sequence voltage balance model at a non-full-phase fault based on acquired circuit information; combines the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct a sequence current model at the fault location; uses the sequence current model and a sequential cyclic iterative algorithm to solve for the positive and negative sequence components of the generator terminal voltage; and generates the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current. This enables accurate assessment of the influence of the positive and negative sequence output of the new energy unit on the power frequency overvoltage level at the fault point during non-full-phase operation of the new energy aggregation system, providing a theoretical basis for control strategy formulation.

[0051] Specifically, by constructing a sequence voltage balance model at the non-full-phase fault location based on the acquired circuit information, mathematical modeling of the voltage variation law of the new energy system under non-full-phase fault conditions was realized, laying the foundation for subsequent current calculations. By combining the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault, a sequence current model at the fault location was constructed, achieving accurate modeling of each sequence component current under the condition of satisfying physical boundary constraints, thus improving the accuracy of fault modeling. By using the sequence current model to solve for the positive and negative sequence components of the generator terminal voltage using a sequence-based iterative algorithm, numerical decoupling of complex coupled electrical variables was achieved, thereby obtaining the stable voltage solution at the generator terminal. By generating the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current, quantitative calculation of the power frequency overvoltage at the fault point was realized, thereby accurately assessing the risk of voltage rise. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0054] Figure 2 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0055] Figure 3 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0056] Figure 4This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0057] Figure 5 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0058] Figure 6 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application.

[0059] Figure 7 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0060] Figure 8 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0061] Figure 9 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0062] Figure 10 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0063] Figure 11 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0064] Figure 12 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control provided in an embodiment of this application;

[0065] Figure 13 This is a schematic block diagram of the system configuration of an electronic device provided in an embodiment of this application;

[0066] Figure 14 This is a schematic diagram of a single-phase open circuit provided in an embodiment of this application;

[0067] Figure 15 This is a schematic diagram of the sequence components of the voltage at the break point and the line current provided in an embodiment of this application;

[0068] Figure 16 This is a schematic diagram of the sequence network model of a new energy collection system that takes into account the negative sequence current control of new energy units, provided in an embodiment of this application.

[0069] Figure 17 This is a schematic diagram of a single-phase open-circuit fault composite sequence network provided in an embodiment of this application;

[0070] Figure 18 This is a flowchart illustrating a solution method for sequential cyclic iteration provided in an embodiment of this application;

[0071] Figure 19 This is a schematic diagram of the voltage output result of a simulation model provided in an embodiment of this application;

[0072] Figure 20 This is a schematic diagram of the voltage output result obtained by the power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and their descriptions are used to explain this application, but are not intended to limit this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0074] This application addresses the power frequency overvoltage problem that easily occurs in new energy collection systems during non-full-phase operation. It aims to analyze the coupling relationship between different sequence components through precise mathematical modeling and iterative solution mechanisms, thereby realizing the quantitative calculation and evaluation of voltage levels during faults and providing support for the formulation of system control strategies.

[0075] The following describes the specific implementation process of the power frequency overvoltage analysis method considering negative sequence current control provided in the embodiments of this application, taking the server as the execution subject as an example.

[0076] Figure 1 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 1 As shown, the power frequency overvoltage analysis method considering negative sequence current control provided in this application includes:

[0077] S101: Construct a sequence voltage balance model at the non-full-phase fault based on the acquired circuit information;

[0078] S102: Combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location;

[0079] S103: The positive and negative sequence components of the terminal voltage are solved using the sequence current model and the sequential cyclic iterative algorithm.

[0080] S104: Generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0081] from Figure 1As shown in the flowchart, this application provides a power frequency overvoltage analysis method that considers negative sequence current control. It constructs a sequence voltage balance model at the fault location based on acquired circuit information; combines the sequence voltage balance model with the three-phase boundary conditions of the fault to construct a sequence current model at the fault location; uses the sequence current model and a sequential iterative algorithm to solve for the positive and negative sequence components of the generator terminal voltage; and generates the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current. This method accurately assesses the influence of the positive and negative sequence output of the new energy unit on the power frequency overvoltage level at the fault point during the non-full-phase operation of the new energy aggregation system, providing a theoretical basis for control strategy formulation.

[0082] Each step is explained in detail below.

[0083] S101: Construct a sequence voltage balance model at the non-full-phase fault based on the acquired circuit information;

[0084] Specifically, the server first constructs a sequence voltage balance model under non-full-phase fault conditions based on the acquired circuit information. This model can reflect the voltage constraint relationship of the fault point in the positive-sequence, negative-sequence, and zero-sequence networks, establish the voltage expression form of the system in each sequence domain, and provide a foundation for subsequent current modeling.

[0085] In one embodiment, the circuit information includes line parameters, fault location, impedance parameters, and topology.

[0086] Figure 2 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 2 As shown, S101 includes:

[0087] S201: Establish a sequence network model after a non-full-phase fault based on the circuit information; the sequence network model includes a positive sequence network model, a negative sequence network model, and a zero sequence network model.

[0088] Specifically, the server first establishes a sequence network model after a non-full-phase fault based on the acquired circuit information. The circuit information includes the structural topology and parameter data (such as impedance and power supply voltage) of various devices in the system, as well as their operating states before and after the fault. To address the symmetry imbalance caused by non-full-phase operation, the symmetric component method is used to model the system, thereby constructing positive-sequence, negative-sequence, and zero-sequence network models respectively. During the modeling process, the characteristics of the new energy unit—acting as a power source in the positive sequence and controllable as a current source in the negative sequence—must be considered to reflect its function under different sequence networks.

[0089] In one embodiment, when a single-line open circuit fault occurs in the power system, the voltage at the break point and the line current flowing into the break point are decomposed into three sequence components: positive, negative, and zero sequence. Taking phase A open circuit as an example, a schematic diagram of a single-phase open circuit is shown below. Figure 14 As shown, the schematic diagram of the sequence components of the voltage and line current at the break point is as follows: Figure 15 As shown.

[0090] Figure 14 and Figure 15 In the middle, Z qk U represents the impedance between the two ends of the unbroken phase break. m U m(1) U m(2) U m(0) (m=a,b,c) represent the three-phase voltages at the break point and their positive and negative zero-sequence components, respectively. m I m(1) I m(2) I m(0) (m=a,b,c) represent the three-phase currents flowing through the break point and their positive and negative zero-sequence components, respectively.

[0091] Taking a phase A disconnection on a 220kV line as an example, the sequence network model of the new energy collection system, which takes into account the negative sequence current control of new energy units, is as follows: Figure 16 As shown. Figure 16 In the middle, E g E represents the infinite power supply voltage. s(1) E s(2) These represent the positive and negative sequence voltages at the inverter output of the new energy unit, respectively; U (1) U (2) U (0) I represents the voltage at the interrupt port of the positive and negative zero sequence network. (1) I (2) I (0) Z represents the current flowing through the break point in the positive and negative zero sequence network; s(1) Z s(2) Z s(0) Z represents the machine-side impedance at the fault location in the positive and negative zero-sequence network, respectively. g(1) Z g(2) Z g(0) These represent the network-side impedance at the fault location in the positive and negative zero-sequence network, respectively.

[0092] S202: Construct the sequence voltage balance model based on the sequence network model.

[0093] Specifically, based on the sequence network model, the server further constructs a sequence voltage balance model. This model reflects the voltage relationships and current transmission paths between different voltage nodes in each sequence network during a fault, forming the basic mathematical framework of the system. The sequence voltage balance model comprehensively considers parameters such as machine-side and grid-side impedance, machine-end sequence voltage, fault point voltage, and current injection, and can accurately describe the generation mechanism and mutual coupling relationship of each sequence component voltage.

[0094] In one embodiment, based on such Figure 16 The sequence network model shown yields the sequence voltage balance model at the break point, as follows:

[0095]

[0096] In the formula, Z (1) Z (2) Z (0) The positive and negative zero sequence network circuits are respectively the machine-side impedance Z. g(n) (n=1,2,0) and the network-side impedance Z s(n) The sum of (n = 1, 2, 0), that is:

[0097]

[0098] The positive and negative zero-sequence impedances on both sides of the fault are shown below:

[0099]

[0100] In the formula, Z l220(1) Z l220(2) Z l220(0) These are the positive and negative zero-sequence components of the 220kV line impedance, respectively; Z l35(1) Z l35(2) These are the positive and negative sequence components of the 35kV line impedance, respectively; Z t35 Z t220 These are the impedances of a 35kV transformer and a 220kV main transformer, respectively; Z grid This is the short-circuit impedance of the power grid.

[0101] The sequence voltage balance model established in the above manner provides a theoretical basis and modeling support for subsequent sequence current solution and power frequency overvoltage assessment, and is the key first step in the entire analysis method.

[0102] S102: Combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location;

[0103] Specifically, the server combines the sequence voltage balance model with the three-phase boundary conditions corresponding to incomplete phase open circuit faults. By performing sequence component transformation on the boundary relationships of voltage and current, a sequence current model reflecting the fault characteristics is formed. This model characterizes the flow path and amplitude variation of each sequence current on the machine side and the grid side.

[0104] Figure 3 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 3 As shown, S102 includes:

[0105] S301: Determine the three-phase boundary conditions of the non-full-phase fault based on the circuit information;

[0106] Specifically, the server needs to determine the three-phase boundary conditions for incomplete phase faults based on circuit information. These boundary conditions mainly describe the physical relationships that the voltage and current of each phase at the fault point should satisfy under incomplete phase disconnection conditions (e.g., phase A disconnection). For example, for the disconnected phase, its current is zero; for the unconnected phase, its phase voltage is represented by the product of the current flowing through the break and the impedance of the break. Boundary constraints are extracted and quantified by analyzing the actual system operating state.

[0107] In one embodiment, taking phase A disconnection as an example, the boundary conditions are as follows:

[0108]

[0109] S302: Convert the three-phase boundary conditions into sequence component boundary conditions;

[0110] Specifically, the server employs the symmetrical component method to convert the aforementioned three-phase boundary conditions into sequence component boundary conditions, enabling unified processing with the sequence voltage balance model. This transformation projects the three-phase voltage and current boundary information into positive-sequence, negative-sequence, and zero-sequence spaces, thereby obtaining independent boundary expressions for each sequence component. This conversion not only facilitates decoupling in mathematical solutions but also more clearly reflects the electromagnetic response characteristics under asymmetric faults.

[0111] In one embodiment, formula (4) is converted into an ordinal component, and the subscript "a" is omitted, resulting in the following boundary conditions for the ordinal component:

[0112]

[0113] Its single-phase open-circuit fault composite sequence network is as follows Figure 17 As shown.

[0114] S303: Construct the sequence current model based on the sequence voltage balance model and the sequence component boundary conditions.

[0115] Specifically, based on the obtained sequence voltage balance model and sequence component boundary conditions, the server constructs a sequence current model at the fault location. This model reflects the flow relationship between each sequence voltage and current on the generator side and the grid side. This sequence current model can not only be used for subsequent iterative solutions to the generator terminal voltage, but also provide an analytical basis for analyzing the impact of the output characteristics of new energy units on system voltage stability.

[0116] In one embodiment, substituting formula (4) into formula (2), the expressions for the positive and negative zero-sequence currents at the break point considering the machine-side negative-sequence source (sequence current model) are as follows:

[0117]

[0118] Where the equivalent impedance Z Σ for:

[0119]

[0120] The sequence current model established by the above method improves the accuracy and engineering applicability of non-full-phase fault modeling by fully integrating physical boundaries and control characteristics. It is one of the fundamental steps to achieve accurate calculation of power frequency overvoltage.

[0121] S103: The positive and negative sequence components of the terminal voltage are solved using the sequence current model and the sequential cyclic iterative algorithm.

[0122] Specifically, based on the established sequence current model, the server further utilizes a cyclic iterative algorithm to solve for the positive and negative sequence components of the new energy generator terminal voltage. Since the positive and negative sequence currents and voltages are coupled under the unit's control characteristics, direct analytical calculation is difficult. Therefore, an initial value setting and step-by-step iteration approach is adopted to achieve a convergent solution for the positive and negative sequence voltages through numerical methods, while ensuring boundary consistency.

[0123] Figure 4 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 4 As shown, S103 includes:

[0124] S401: Simplify the sequence current model and set the initial value of the positive sequence component of the terminal voltage;

[0125] Specifically, to effectively solve for the positive and negative sequence components of the terminal voltage of new energy generating units, a numerical calculation method based on a sequential cyclic iterative algorithm was adopted. This method can achieve a stable and accurate voltage solution process even under the conditions of coupled positive and negative sequence components and difficult analytical expression.

[0126] The server moderately simplifies the established sequence current model, retaining key variables that affect sequence voltage changes. Based on this, to initiate the iterative process, an initial value for the positive sequence component of the terminal voltage needs to be set. This initial value can be set according to the system's rated voltage or steady-state operating condition, serving as the starting point for the iterative algorithm.

[0127] In one embodiment, if qk is a circuit breaker break, i.e., Z qk If = 0, then the sequence current model can be simplified to:

[0128]

[0129] S402: Using the simplified sequence current model and the initial value of the positive sequence component of the terminal voltage, the positive and negative sequence components of the terminal voltage are solved by a sequential cyclic iterative algorithm.

[0130] Specifically, traditional new energy generating units mostly adopt grid-connected control. In the positive-sequence network, the unit exhibits power source characteristics externally, while in the negative-sequence network, it exhibits current source characteristics. The positive and negative sequence voltages at the generator terminals can be obtained by solving for the positive-sequence power and negative-sequence current. However, considering the negative-sequence source at the generator terminals, the analytical expression for the positive-sequence power becomes highly complex, and solving for both the positive-sequence power and negative-sequence current is also difficult. Therefore, a sequential iterative solution method is adopted.

[0131] Based on a simplified sequence current model and initial values, the server enters a sequence-based iterative solution process. This process solves for the positive and negative sequence components of the terminal voltage in an alternating update manner. In each iteration, the negative sequence component is first solved based on the known positive sequence component, and then the positive sequence component is updated based on the obtained negative sequence component. Through this cyclical alternation, the solution gradually converges to a stable voltage solution.

[0132] In one embodiment, the initial value E of the positive sequence voltage at the terminal is set. (0) s(1) =1∠0.

[0133] By employing the above method, while considering the negative sequence current control characteristics of new energy units, direct analysis of complex algebraic equations can be avoided, thus improving the stability and applicability of the calculation. Through sequential cyclic iteration, the internal coupling relationship of the system is decoupled, thereby achieving efficient numerical solutions. This not only enables accurate solutions for the positive and negative sequence components of the generator terminal voltage but also lays the foundation for subsequent calculations of power frequency overvoltages at fault points.

[0134] Figure 5 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 5 As shown, S402 includes:

[0135] S501: Set the negative sequence component of the machine terminal output current to a preset negative sequence current reference value, and combine the simplified sequence current model and the positive sequence component of the machine terminal voltage to calculate the negative sequence component of the machine terminal voltage.

[0136] Specifically, during the iteration process, the server sets the negative sequence component of the terminal output current to a preset negative sequence current reference value. Combined with the simplified sequence current model and the positive sequence voltage component set for the current round, the negative sequence component of the terminal voltage can be solved accordingly, which serves as the calculation result of the negative sequence voltage for this round.

[0137] In one embodiment, the negative sequence current reference value can be set by the system operation strategy or controller, for example, based on the current support capability of the new energy unit under asymmetrical operating conditions.

[0138] S502: Set the positive sequence component of the generator terminal output current to a preset positive sequence current reference value, and calculate the positive sequence component of the generator terminal voltage by combining the simplified sequence current model, the negative sequence component of the generator terminal voltage, and the preset positive sequence output constraint model.

[0139] Specifically, based on the obtained negative sequence voltage component, the server sets the positive sequence component of the terminal output current to a preset positive sequence current reference value, and solves the problem by combining the current negative sequence voltage, the simplified sequence current model, and the positive sequence output constraint, thereby obtaining the updated positive sequence voltage component.

[0140] S503: Iteratively execute the above operation until the positive sequence component of the terminal voltage converges, and obtain the positive and negative sequence components of the terminal voltage.

[0141] Specifically, the server continuously repeats the above alternating positive and negative sequence update steps to form a complete iterative process. In each iteration, the positive and negative sequence voltages form a feedback loop through mutual input and output. Finally, after satisfying the convergence criterion, the iteration terminates, and a stable positive and negative sequence voltage solution is obtained.

[0142] In one embodiment, the solution method of sequential cyclic iteration is as follows: Figure 18 As shown, the specific steps are as follows:

[0143] Step 1: Set the initial value E of the positive sequence voltage at the machine terminal. (0) s(1) =1∠0.

[0144] Step 2: According to the second equation of formula (8), set the negative sequence current I at the machine terminal. (2) Equal to the negative sequence current reference value I ref(2) Solve for the negative sequence voltage E at the output terminal. (k) s(2) (k≥1).

[0145] Step 3: Convert the negative sequence voltage E at the machine terminals(k) s(2) Substituting into the first expression of formula (8), let the positive sequence current I output at the terminal be... (1) Equal to the positive sequence current reference value I ref(1) Solve for the positive-sequence active power output P(E) of the unit. s(1) The positive-sequence active power reference value P is equal to the positive-sequence active power reference value. ref The positive sequence reactive power output of the unit is Q(E) s(1) The positive-sequence reactive power reference value Q is equal to the positive-sequence reactive power reference value. ref (P (1) +jQ (1) =P ref(1) +jQ ref(1) Solve for the positive sequence voltage E at the generator terminals. (k) s(1) (k≥1).

[0146] Step 4: Determine the positive sequence voltage E at the machine terminals (k) s(1) If convergence has occurred, the process ends and outputs E. (k) s(1) E (k) s(2) If it does not converge, repeat steps two and three.

[0147] The iterative process described above effectively handles the complex electromagnetic characteristics of new energy power units, such as controllable output current and coupling of positive and negative sequence voltages. It avoids the difficulty of directly solving large-scale nonlinear equations, thus improving the numerical stability and engineering feasibility of the method. The final output positive and negative sequence voltage components provide an accurate input basis for subsequent calculations of power frequency overvoltages at fault points.

[0148] In one embodiment, the convergence criterion can be that the voltage change is less than a set threshold, at which point the iteration terminates and a stable positive and negative sequence voltage solution is obtained.

[0149] S104: Generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0150] Specifically, based on the positive and negative sequence components of the terminal voltage obtained from the above solution, and combined with the already acquired positive and negative sequence components of the terminal output current, the server further calculates the positive and zero sequence components of the terminal voltage at the fault point. By performing symmetrical component inverse transformation on these sequence components, the final three-phase power frequency voltage waveform can be obtained, thereby obtaining the power frequency overvoltage value during the fault, achieving the voltage assessment and analysis objective under this operating condition.

[0151] This application fully considers the negative sequence support capability of new energy units under non-full-phase operating conditions. Based on physical equivalent modeling and numerical iterative calculation, it realizes the accurate restoration of the fault voltage change trend, which can be effectively used for the research on fault response characteristics and the optimization design of control strategies of new energy systems.

[0152] Figure 6 This is a flowchart illustrating a power frequency overvoltage analysis method considering negative sequence current control provided in an embodiment of this application, as shown below. Figure 6 As shown, S104 includes:

[0153] S601: Calculate the positive and negative zero sequence components of the generator-side voltage at the fault location based on the positive and negative sequence components of the generator-side voltage and the obtained positive and negative sequence components of the generator-side output current.

[0154] Specifically, the server calculates the positive, negative, and zero-sequence components of the machine-side voltage at the fault location based on the positive and negative sequence components of the machine-side voltage and the positive and negative sequence components of the acquired machine-side output current.

[0155] In one embodiment, the machine-side voltage at the fault location is calculated by combining the terminal voltage and the current flowing through the fault location, as shown in the following equation:

[0156]

[0157] In the formula, U fq(1) U fq(2) U fq(0) This represents the positive and negative zero-sequence components of the machine-side voltage at the fault location in the positive and negative zero-sequence network.

[0158] S602: Perform symmetrical component inverse transformation on the positive and negative zero-sequence components of the machine-side voltage at the fault location to obtain the power frequency overvoltage at the fault location.

[0159] Specifically, the server performs a symmetrical component inverse transform on the obtained positive-sequence, negative-sequence, and zero-sequence voltage components, restoring the voltage quantities in the sequence domain to three-phase voltages in phasor form. By applying the inverse transform matrix, the sequence components are transformed into three-phase voltages A, B, and C, from which the amplitude of the three-phase voltage at the fault location during the open-circuit fault can be obtained, i.e., the power frequency overvoltage at the fault location. The power frequency overvoltage at the fault location reflects the most severe voltage rise level of the system under the current fault condition and unit control strategy, and can serve as an important reference for the formulation of overvoltage suppression strategies and the design of equipment withstand voltage.

[0160] In one embodiment, the amplitudes of the three-phase voltages (power frequency overvoltage at the fault location) on the machine side can be calculated separately based on the positive and negative zero-sequence components of the voltage at the fault location:

[0161]

[0162] In the formula, α = e j120° , j represents the imaginary unit.

[0163] In one embodiment, the above method is verified by comparing the three-phase voltage curves at the fault location during non-full-phase operation. The voltage output results of the simulation model are as follows: Figure 19As shown, the voltage output result obtained by the above method in this application is as follows: Figure 20 As shown, the two sets of curves have a high degree of fit, and the experimental results verify the effectiveness of the above method.

[0164] Through the above steps, the complete conversion process of power frequency overvoltage at the fault point is realized from the measurement information at the machine end, ensuring the closed loop of the entire analysis path and its application value.

[0165] This application provides a power frequency overvoltage analysis method that considers negative sequence current control. It constructs a sequence voltage balance model at the fault location based on acquired circuit information; combines this model with the three-phase boundary conditions of the fault to construct a sequence current model at the fault location; uses the sequence current model and a sequential iterative algorithm to solve for the positive and negative sequence components of the generator terminal voltage; and generates the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current. This method accurately assesses the influence of the positive and negative sequence output of the new energy unit on the power frequency overvoltage level at the fault point during the non-full-phase operation of the new energy aggregation system, providing a theoretical basis for control strategy formulation.

[0166] Specifically, by constructing a sequence voltage balance model at the non-full-phase fault location based on the acquired circuit information, mathematical modeling of the voltage variation law of the new energy system under non-full-phase fault conditions was realized, laying the foundation for subsequent current calculations. By combining the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault, a sequence current model at the fault location was constructed, achieving accurate modeling of each sequence component current under the condition of satisfying physical boundary constraints, thus improving the accuracy of fault modeling. By using the sequence current model to solve for the positive and negative sequence components of the generator terminal voltage using a sequence-based iterative algorithm, numerical decoupling of complex coupled electrical variables was achieved, thereby obtaining the stable voltage solution at the generator terminal. By generating the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current, quantitative calculation of the power frequency overvoltage at the fault point was realized, thereby accurately assessing the risk of voltage rise.

[0167] Based on the same inventive concept, this application also provides a power frequency overvoltage analysis device considering negative sequence current control, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of the power frequency overvoltage analysis device considering negative sequence current control is similar to that of the power frequency overvoltage analysis method considering negative sequence current control, the implementation of the power frequency overvoltage analysis device considering negative sequence current control can refer to the implementation of the software performance benchmark determination method, and will not be repeated. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0168] Figure 7 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application, as shown below. Figure 7 As shown, the power frequency overvoltage analysis device considering negative sequence current control provided in this application includes:

[0169] Sequence voltage balance model building unit 701 is used to build a sequence voltage balance model at the non-full-phase fault location based on the acquired circuit information;

[0170] The sequence current model construction unit 702 is used to combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location.

[0171] Terminal voltage solving unit 703 is used to solve the positive and negative sequence components of the terminal voltage using the sequence current model and a sequential cyclic iterative algorithm.

[0172] The power frequency overvoltage generation unit 704 is used to generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the acquired terminal output current.

[0173] Figure 8 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application. Figure 7 Based on the embodiments, further, such as Figure 8 As shown, the sequence voltage balance model construction unit 701 includes:

[0174] The sequence network model establishment module 801 is used to establish a sequence network model after a non-full-phase fault based on the circuit information; the sequence network model includes a positive sequence network model, a negative sequence network model, and a zero sequence network model.

[0175] The sequence voltage balance model construction module 802 is used to construct the sequence voltage balance model based on the sequence network model.

[0176] Figure 9 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application. Figure 7 Based on the embodiments, further, such as Figure 9 As shown, the sequence current model construction unit 702 includes:

[0177] The three-phase boundary condition determination module 901 is used to determine the three-phase boundary conditions of the non-full-phase fault based on the circuit information.

[0178] The sequence component boundary condition determination module 902 is used to convert the three-phase boundary conditions into sequence component boundary conditions.

[0179] The sequence current model construction module 903 is used to construct the sequence current model based on the sequence voltage balance model and the sequence component boundary conditions.

[0180] Figure 10 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application. Figure 7 Based on the embodiments, further, such as Figure 10 As shown, the terminal voltage calculation unit 703 includes:

[0181] Sequence current model simplification module 1001 is used to simplify the sequence current model and set the initial value of the positive sequence component of the terminal voltage;

[0182] Terminal voltage solution module 1002 is used to solve for the positive and negative sequence components of the terminal voltage using a cyclic iterative algorithm based on a simplified sequence current model and the initial value of the positive sequence component of the terminal voltage.

[0183] Figure 11 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application. Figure 10 Based on the embodiments, further, such as Figure 11 As shown, the terminal voltage calculation module 1002 includes:

[0184] The negative sequence component calculation submodule 1101 is used to set the negative sequence component of the machine terminal output current to a preset negative sequence current reference value, and calculate the negative sequence component of the machine terminal voltage by combining the simplified sequence current model and the positive sequence component of the machine terminal voltage.

[0185] The positive sequence component calculation submodule 1102 is used to set the positive sequence component of the terminal output current to a preset positive sequence current reference value, and calculate the positive sequence component of the terminal voltage by combining the simplified sequence current model, the negative sequence component of the terminal voltage and the preset positive sequence output constraint model.

[0186] The iterative operation submodule 1103 is used to iteratively execute the above operation until the positive sequence component of the terminal voltage converges, thereby obtaining the positive and negative sequence components of the terminal voltage.

[0187] Figure 12 This is a schematic diagram of the structure of a power frequency overvoltage analysis device considering negative sequence current control according to an embodiment of this application. Figure 7 Based on the embodiments, further, such as Figure 12 As shown, the power frequency overvoltage generation unit 704 includes:

[0188] The fault location machine-side voltage calculation module 1201 is used to calculate the positive and negative zero sequence components of the fault location machine-side voltage based on the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the acquired terminal output current.

[0189] The power frequency overvoltage generation module 1202 is used to perform symmetrical component inverse transformation on the positive and negative zero sequence components of the machine-side voltage at the fault location to obtain the power frequency overvoltage at the fault location.

[0190] This application provides a power frequency overvoltage analysis method and apparatus that considers negative sequence current control. It constructs a sequence voltage balance model at a non-full-phase fault based on acquired circuit information; combines the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct a sequence current model at the fault location; uses the sequence current model and a sequential cyclic iterative algorithm to solve for the positive and negative sequence components of the generator terminal voltage; and generates the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current. This enables accurate assessment of the influence of the positive and negative sequence output of the new energy unit on the power frequency overvoltage level at the fault point during non-full-phase operation of the new energy aggregation system, providing a theoretical basis for control strategy formulation.

[0191] Specifically, by constructing a sequence voltage balance model at the non-full-phase fault location based on the acquired circuit information, mathematical modeling of the voltage variation law of the new energy system under non-full-phase fault conditions was realized, laying the foundation for subsequent current calculations. By combining the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault, a sequence current model at the fault location was constructed, achieving accurate modeling of each sequence component current under the condition of satisfying physical boundary constraints, thus improving the accuracy of fault modeling. By using the sequence current model to solve for the positive and negative sequence components of the generator terminal voltage using a sequence-based iterative algorithm, numerical decoupling of complex coupled electrical variables was achieved, thereby obtaining the stable voltage solution at the generator terminal. By generating the power frequency overvoltage at the fault location based on the positive and negative sequence components of the generator terminal voltage and the acquired positive and negative sequence components of the generator terminal output current, quantitative calculation of the power frequency overvoltage at the fault point was realized, thereby accurately assessing the risk of voltage rise.

[0192] From a hardware perspective, in order to address the problems in the prior art, this application provides an embodiment of an electronic device for implementing all or part of the power frequency overvoltage analysis method considering negative sequence current control. The electronic device specifically includes the following components:

[0193] The system comprises a processor, a memory, a communications interface, and a bus; wherein the processor, memory, and communications interface communicate with each other via the bus; the communications interface is used to realize information transmission between the power frequency overvoltage analysis device considering negative sequence current control and core business systems, user terminals, and related databases and other related devices; the logic controller can be a desktop computer, tablet computer, or mobile terminal, etc., and this embodiment is not limited to these. In this embodiment, the logic controller can be implemented with reference to the embodiments of the power frequency overvoltage analysis method considering negative sequence current control and the embodiments of the power frequency overvoltage analysis device considering negative sequence current control in the embodiments, the contents of which are incorporated herein, and repeated details will not be described again.

[0194] It is understood that the user terminal may include smartphones, tablet computers, network set-top boxes, portable computers, desktop computers, personal digital assistants (PDAs), in-vehicle devices, smart wearable devices, etc. Among these, the smart wearable devices may include smart glasses, smartwatches, smart bracelets, etc.

[0195] In practical applications, the power frequency overvoltage analysis method considering negative sequence current control can be partially executed on the electronic device side as described above, or all operations can be completed in the client device. The choice can be made based on the processing power of the client device and the limitations of the user's usage scenario. This application does not impose any limitations on this. If all operations are completed in the client device, the client device may further include a processor.

[0196] The aforementioned client device may have a communication module (i.e., a communication unit) that can communicate with a remote server to achieve data transmission. The server may include a server on the task scheduling center side; in other implementation scenarios, it may also include a server on an intermediate platform, such as a server on a third-party server platform that has a communication link with the task scheduling center server. The server may include a single computer device, a server cluster consisting of multiple servers, or a distributed server structure.

[0197] Figure 13 This is a schematic block diagram illustrating the system configuration of the electronic device 9600 according to an embodiment of this application. Figure 13As shown, the electronic device 9600 may include a central processing unit 9100 and a memory 9140; the memory 9140 is coupled to the central processing unit 9100. It is worth noting that... Figure 13 This is an example; other types of structures can also be used to supplement or replace this structure to achieve telecommunications functions or other functions.

[0198] In one embodiment, the power frequency overvoltage analysis method considering negative sequence current control can be integrated into the central processing unit 9100. The central processing unit 9100 can be configured to perform the following control:

[0199] S101: Construct a sequence voltage balance model at the non-full-phase fault based on the acquired circuit information;

[0200] S102: Combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location;

[0201] S103: The positive and negative sequence components of the terminal voltage are solved using the sequence current model and the sequential cyclic iterative algorithm.

[0202] S104: Generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0203] As can be seen from the above description, this application realizes the accurate assessment of the impact of the positive and negative sequence outputs of the new energy unit on the power frequency overvoltage level at the fault point during the non-full-phase operation of the new energy collection system, providing a theoretical basis for the formulation of control strategies.

[0204] In another embodiment, the power frequency overvoltage analysis device that takes into account negative sequence current control can be configured separately from the central processing unit 9100. For example, the power frequency overvoltage analysis device that takes into account negative sequence current control can be configured as a chip connected to the central processing unit 9100, and the function of the power frequency overvoltage analysis method that takes into account negative sequence current control can be realized through the control of the central processing unit.

[0205] like Figure 13 As shown, the electronic device 9600 may further include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is worth noting that the electronic device 9600 does not necessarily need to include these components. Figure 13 All components shown; in addition, the electronic device 9600 may also include Figure 13 For components not shown, please refer to existing technologies.

[0206] like Figure 13As shown, the central processing unit 9100, sometimes also referred to as a controller or operating control, may include a microprocessor or other processor device and / or logic device, which receives inputs and controls the operation of various components of the electronic device 9600.

[0207] The memory 9140 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store the aforementioned failure-related information, and also store a program for executing that information. The central processing unit 9100 may execute the program stored in the memory 9140 to perform information storage or processing, etc.

[0208] Input unit 9120 provides input to central processing unit 9100. Input unit 9120 may be, for example, a keypad or touch input device. Power supply 9170 provides power to electronic device 9600. Display 9160 displays images and text. Display may be, for example, an LCD display, but is not limited thereto.

[0209] The memory 9140 can be a solid-state memory, such as a read-only memory (ROM), random access memory (RAM), a SIM card, etc. It can also be a memory that retains information even when power is off, can be selectively erased, and contains more data; examples of this type of memory are sometimes referred to as EPROMs. The memory 9140 can also be some other type of device. The memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application / function storage unit 9142 for storing application programs and function programs or processes for executing the operation of the electronic device 9600 via the central processing unit 9100.

[0210] The memory 9140 may also include a data storage unit 9143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 9144 of the memory 9140 may include various drivers for the electronic device's communication functions and / or for performing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0211] The communication module 9110 is a transmitter / receiver 9110 that transmits and receives signals via the antenna 9111. The communication module (transmitter / receiver) 9110 is coupled to the central processing unit 9100 to provide input signals and receive output signals, which can be the same as in a conventional mobile communication terminal.

[0212] Based on different communication technologies, multiple communication modules 9110 can be configured in the same electronic device, such as cellular network modules, Bluetooth modules, and / or wireless LAN modules. The communication module (transmitter / receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide audio output via the speaker 9131 and receive audio input from the microphone 9132, thereby realizing typical telecommunications functions. The audio processor 9130 may include any suitable buffer, decoder, amplifier, etc. Additionally, the audio processor 9130 is also coupled to a central processing unit 9100, enabling on-device recording via the microphone 9132 and on-device playback of stored sound via the speaker 9131.

[0213] Embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the power frequency overvoltage analysis method considering negative sequence current control, in which the execution subject is a server or client as described in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the power frequency overvoltage analysis method considering negative sequence current control, in which the execution subject is a server or client as described in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0214] S101: Construct a sequence voltage balance model at the non-full-phase fault based on the acquired circuit information;

[0215] S102: Combine the sequence voltage balance model with the three-phase boundary conditions of the non-full-phase fault to construct the sequence current model at the fault location;

[0216] S103: The positive and negative sequence components of the terminal voltage are solved using the sequence current model and the sequential cyclic iterative algorithm.

[0217] S104: Generate a power frequency overvoltage at the fault location based on the positive and negative sequence components of the terminal voltage and the obtained positive and negative sequence components of the terminal output current.

[0218] As can be seen from the above description, this application realizes the accurate assessment of the impact of the positive and negative sequence outputs of the new energy unit on the power frequency overvoltage level at the fault point during the non-full-phase operation of the new energy collection system, providing a theoretical basis for the formulation of control strategies.

[0219] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0220] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0221] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0222] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0223] This application uses specific embodiments to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A power frequency overvoltage analysis method taking into account negative sequence current control, characterized in that, The method comprises the following steps: constructing a sequence voltage balance model at the non-solid fault position based on the obtained circuit information; combining the sequence voltage balance model with three-phase boundary conditions of the non-solid fault to construct a sequence current model at the fault position; solving positive and negative sequence components of the terminal voltage by using the sequence current model and a sequence cycle iteration algorithm; generating a power frequency overvoltage at the fault position according to the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the obtained terminal output current.

2. The power frequency overvoltage analysis method with negative sequence current control according to claim 1, characterized in that, The step of constructing the sequence voltage balance model at the non-solid fault position based on the obtained circuit information comprises the following steps: establishing a sequence network model after the non-solid fault based on the circuit information; the sequence network model comprises a positive sequence network model, a negative sequence network model and a zero sequence network model; constructing the sequence voltage balance model based on the sequence network model.

3. The power frequency overvoltage analysis method with negative sequence current control according to claim 1, characterized in that, The step of combining the sequence voltage balance model with three-phase boundary conditions of the non-solid fault to construct a sequence current model at the fault position comprises the following steps: determining the three-phase boundary conditions of the non-solid fault based on the circuit information; converting the three-phase boundary conditions into sequence component boundary conditions; constructing the sequence current model according to the sequence voltage balance model and the sequence component boundary conditions.

4. The power frequency overvoltage analysis method with negative sequence current control according to claim 1, characterized in that, The step of solving positive and negative sequence components of the terminal voltage by using the sequence current model and a sequence cycle iteration algorithm comprises the following steps: simplifying the sequence current model and setting an initial value of the positive sequence component of the terminal voltage; solving positive and negative sequence components of the terminal voltage by using the simplified sequence current model and the initial value of the positive sequence component of the terminal voltage and the sequence cycle iteration algorithm.

5. The power frequency overvoltage analysis method with negative sequence current control according to claim 4, characterized in that, The step of solving positive and negative sequence components of the terminal voltage by using the simplified sequence current model and the initial value of the positive sequence component of the terminal voltage and the sequence cycle iteration algorithm comprises the following steps: setting the negative sequence component of the terminal output current as a preset negative sequence current reference value, and calculating the negative sequence component of the terminal voltage by combining the simplified sequence current model and the positive sequence component of the terminal voltage; setting the positive sequence component of the terminal output current as a preset positive sequence current reference value, and calculating the positive sequence component of the terminal voltage by combining the simplified sequence current model, the negative sequence component of the terminal voltage and a preset positive sequence output constraint model; iteratively performing the above operations until the positive sequence component of the terminal voltage converges, so as to obtain the positive and negative sequence components of the terminal voltage.

6. The power frequency overvoltage analysis method with negative sequence current control according to claim 1, characterized in that, The step of generating a power frequency overvoltage at the fault position according to the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the obtained terminal output current comprises the following steps: calculating positive and negative zero sequence components of the machine-side voltage at the fault position according to the positive and negative sequence components of the terminal voltage and the positive and negative sequence components of the obtained terminal output current; performing symmetrical component inverse transformation on the positive and negative zero sequence components of the machine-side voltage at the fault position to obtain the power frequency overvoltage at the fault position.

7. A power frequency overvoltage analysis device taking into account negative sequence current control, characterized by The method comprises the following steps: a sequence voltage balance model construction unit is configured to construct a sequence voltage balance model at the non-solid fault position based on obtained circuit information; a sequence current model construction unit is configured to combine the sequence voltage balance model with three-phase boundary conditions of the non-solid fault to construct a sequence current model at the fault position; a terminal voltage solving unit is configured to solve positive and negative sequence components of the terminal voltage by using the sequence current model and a sequence cycle iteration algorithm. The power frequency overvoltage generating unit is configured to generate the power frequency overvoltage at the fault position according to the positive and negative sequence components of the machine terminal voltage and the positive and negative sequence components of the obtained machine terminal output current.

8. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the method in any one of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program implements the method in any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterised in that, The computer program product comprises a computer program, and the computer program implements the method in any one of claims 1 to 6 when executed by a processor.

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