An off-grid wind power hydrogen production system black start power supply capacity calculation method, device, storage medium and product

Abstract

The present disclosure relates to the technical field of power system black start, and particularly relates to a method and device for calculating black start power supply capacity of an off-grid wind power hydrogen production system, a storage medium and a product. The method comprises: constructing an equivalent circuit model of a primary system in the off-grid wind power hydrogen production system; performing power flow calculation according to the equivalent circuit model of the primary system to obtain a power flow calculation result, the power flow calculation result being used to indicate operating parameters of the primary system in a black start process of the off-grid wind power hydrogen production system; and determining black start power supply capacity according to the power flow calculation result, the black start power supply capacity being a maximum power capacity required to be provided by a power supply in the black start process. With the aid of accurate model construction and rigorous mathematical calculation, the present disclosure embodiment significantly improves the accuracy of black start power supply capacity estimation, makes the calculation result closer to actual power consumption demand, and thus effectively reduces design redundancy and saves project investment cost.

Description

Technical Field

[0001] This disclosure relates to the field of black start technology for power systems, and in particular to a method, apparatus, storage medium, and product for calculating the black start power capacity of an off-grid wind power hydrogen production system. Background Technology

[0002] In off-grid wind power to hydrogen production systems, determining the black start power supply capacity is a crucial step. Related technologies primarily rely on engineers' experience to estimate the power requirements of the wind farm and electrolyzer plant, allowing for a significant margin in determining the black start power supply capacity.

[0003] However, this approach has obvious drawbacks: on the one hand, relying solely on experience to estimate the actual power consumption of the system is difficult to accurately grasp, resulting in a large deviation in capacity estimation; on the other hand, reserving too much margin will increase project investment costs and cause waste of resources.

[0004] Therefore, there is an urgent need for a more scientific and accurate method for calculating the capacity of black-start power supplies to address the shortcomings of related technologies and achieve a balance between optimizing project investment and ensuring the reliability of system operation. Summary of the Invention

[0005] In view of this, this disclosure proposes a method, device, storage medium and product for calculating the black start power supply capacity of an off-grid wind power hydrogen production system.

[0006] According to one aspect of this disclosure, a method for calculating the black start power capacity of an off-grid wind power hydrogen production system is provided, the method comprising:

[0007] Construct an equivalent circuit model of the primary system in the off-grid wind power hydrogen production system;

[0008] Power flow calculation is performed based on the equivalent circuit model of the primary system to obtain power flow calculation results. The power flow calculation results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system.

[0009] Based on the power flow calculation results, the black start power supply capacity is determined, which is the maximum power capacity required by the power supply during the black start process.

[0010] In one possible implementation, the primary system includes multiple primary devices, and constructing an equivalent circuit model of the primary system in the off-grid wind power hydrogen production system includes:

[0011] Construct a unified branch model for each of the multiple primary devices, the unified branch model being used to indicate the electrical characteristics of the primary devices;

[0012] The unified branch models of the multiple primary devices are integrated to obtain the equivalent circuit model of the primary system.

[0013] In another possible implementation, the plurality of primary devices include a doubly fed induction generator (DFIG) and other devices, including one or more of transmission lines, transformers, and phase shifters.

[0014] In another possible implementation, constructing the unified branch model for each of the plurality of primary devices includes:

[0015] For each of the primary devices, determine the electrical parameters of the primary device;

[0016] Based on the electrical parameters of the primary equipment and the corresponding preset circuit model, determine the equivalent model parameters of the primary equipment;

[0017] Substituting the equivalent model parameters into the preset circuit model yields the unified branch model of the primary equipment.

[0018] In another possible implementation, the power flow calculation results include the active and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage magnitude and phase of each node.

[0019] In another possible implementation, determining the black-start power supply capacity based on the power flow calculation results includes:

[0020] Based on the power flow calculation results, determine the total active power and total reactive power required by the primary system during the black start process;

[0021] The black-start power supply capacity is determined based on the total active power and total reactive power required by the primary system.

[0022] According to another aspect of this disclosure, a black start power capacity calculation device for an off-grid wind power hydrogen production system is provided, the device comprising:

[0023] The construction module is used to construct the equivalent circuit model of the primary system in the off-grid wind power hydrogen production system;

[0024] The calculation module is used to perform power flow calculation based on the equivalent circuit model of the primary system and obtain the power flow calculation result. The power flow calculation result is used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system.

[0025] The determination module is used to determine the black-start power supply capacity based on the power flow calculation results, wherein the black-start power supply capacity is the maximum power capacity required by the power supply during the black-start process.

[0026] In one possible implementation, the primary system includes multiple primary devices, and the building module is further configured to:

[0027] Construct a unified branch model for each of the multiple primary devices, the unified branch model being used to indicate the electrical characteristics of the primary devices;

[0028] The unified branch models of the multiple primary devices are integrated to obtain the equivalent circuit model of the primary system.

[0029] In another possible implementation, the plurality of primary devices include DFIGs and other devices, which include one or more of transmission lines, transformers, and phase shifters.

[0030] In another possible implementation, the building module is also used for:

[0031] For each of the primary devices, determine the electrical parameters of the primary device;

[0032] Based on the electrical parameters of the primary equipment and the corresponding preset circuit model, determine the equivalent model parameters of the primary equipment;

[0033] Substituting the equivalent model parameters into the preset circuit model yields the unified branch model of the primary equipment.

[0034] In another possible implementation, the power flow calculation results include the active and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage magnitude and phase of each node.

[0035] In another possible implementation, the determining module is further configured to:

[0036] Based on the power flow calculation results, determine the total active power and total reactive power required by the primary system during the black start process;

[0037] The black-start power supply capacity is determined based on the total active power and total reactive power required by the primary system.

[0038] According to another aspect of this disclosure, a black start power capacity calculation device for an off-grid wind power hydrogen production system is provided, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0039] According to another aspect of this disclosure, a non-volatile computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the above-described method.

[0040] According to another aspect of this disclosure, a computer program product is provided, including a computer program or a non-volatile computer-readable storage medium carrying the computer program, wherein the computer program, when executed by a processor, implements the steps of the above-described method.

[0041] This disclosure proposes a method for calculating the black-start power supply capacity of an off-grid wind power-to-hydrogen system. This method constructs an equivalent circuit model of the primary system in the off-grid wind power-to-hydrogen system, performs power flow calculations based on this model, and obtains the power flow calculation results. These results indicate the operating parameters of the primary system during the black-start process. By analyzing the dynamic power consumption characteristics of the primary system during the black-start process, this method can scientifically and accurately determine the maximum power capacity required for the black-start power supply. Compared to traditional methods relying on empirical estimation, this method significantly improves the scientific rigor and accuracy of capacity calculations, ensuring that the calculation results are closer to actual needs. It effectively reduces resource waste caused by excessive margin requirements, thereby significantly reducing project investment costs and improving project economics.

[0042] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0043] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0044] Figure 1 A flowchart illustrating a method for calculating the black start power capacity of an off-grid wind power hydrogen production system provided in an exemplary embodiment of this disclosure is shown.

[0045] Figure 2 A schematic diagram of the electrical connections of an off-grid wind power hydrogen production system provided in an exemplary embodiment of this disclosure is shown.

[0046] Figure 3 A schematic diagram of the power network topology of an off-grid wind power hydrogen production system provided in an exemplary embodiment of this disclosure is shown.

[0047] Figure 4 A schematic diagram of a branch model used in a preset software package provided in an exemplary embodiment of this disclosure is shown.

[0048] Figure 5 A schematic diagram of a uniform branch model of a transmission line provided in an exemplary embodiment of this disclosure is shown.

[0049] Figure 6A schematic diagram of a uniform branch circuit model of a transformer provided in an exemplary embodiment of this disclosure is shown.

[0050] Figure 7 A circuit diagram of a 24-pulse rectifier phase-shifting transformer provided in an exemplary embodiment of this disclosure is shown.

[0051] Figure 8 A simplified circuit diagram of a 24-pulse rectifier phase-shifting transformer provided in an exemplary embodiment of this disclosure is shown.

[0052] Figure 9 A schematic diagram of an asynchronous motor steady-state model provided in an exemplary embodiment of this disclosure is shown.

[0053] Figure 10 A schematic diagram of a DFIG equivalent current source provided in an exemplary embodiment of this disclosure is shown.

[0054] Figure 11 A schematic diagram of an equivalent circuit model of a primary system provided in an exemplary embodiment of this disclosure is shown.

[0055] Figure 12 This diagram illustrates the setting of initial bus parameters provided in an exemplary embodiment of this disclosure.

[0056] Figure 13 A schematic diagram illustrating the setting of generator initial parameters provided in an exemplary embodiment of this disclosure is shown.

[0057] Figure 14 This diagram illustrates the setting of line parameters provided in an exemplary embodiment of the present disclosure.

[0058] Figure 15 A schematic diagram showing the power flow calculation results provided by an exemplary embodiment of this disclosure is illustrated.

[0059] Figure 16 This is a block diagram illustrating an apparatus according to an exemplary embodiment. Detailed Implementation

[0060] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0061] As used herein, the terms “comprising,” “including,” “having,” or variations thereof are open-ended and include one or more of the stated features, integrals, elements, steps, components, or functions, but do not exclude the presence or addition of one or more other features, integrals, elements, steps, components, functions, or groups thereof.

[0062] When an element is referred to as “connected,” “coupled,” “responding,” or a variation thereof relative to another element, it may be directly connected, coupled, or responding to another element, or there may be an intermediate element present.

[0063] Although the terms first, second, third, etc., may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another. Therefore, without departing from the teachings of the inventive concept, a first element / operation in some embodiments may be referred to as a second element / operation in other embodiments.

[0064] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0065] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0066] First, some terms used in the embodiments of this disclosure will be introduced.

[0067] 1. Off-grid wind power hydrogen production system: This is a system that converts wind energy into electrical energy, and then produces hydrogen through water electrolysis. It typically operates independently of the power grid. Off-grid wind power hydrogen production systems are suitable for remote areas, islands, or areas with insufficient power grid coverage. Its main components include wind turbines, electrolyzers, hydrogen storage equipment, and power conversion equipment.

[0068] 2. Primary System: This refers to the overall system composed of primary equipment, used to realize the production, transmission, distribution, and conversion of electrical energy. It includes all equipment and circuit parts directly involved in electrical energy processing and is the core component of the power system. In contrast to the primary system is the secondary system, which mainly includes auxiliary equipment such as control, protection, and communication systems, used to monitor and manage the operation of the primary system.

[0069] 3. Primary Equipment: This refers to equipment directly involved in the production, transmission, distribution, and conversion of electrical energy. This equipment is directly related to the physical processes of electrical energy and typically operates in high-voltage, high-current environments. The main function of primary equipment is to realize the generation, transmission, and distribution of electrical energy, ensuring the normal operation of the power system. In off-grid wind power to hydrogen production systems, the primary system mainly includes transmission lines, transformers, phase shifters, DFIGs, and other primary equipment. Specific configurations can be flexibly selected from one or more of these based on system requirements. This equipment is responsible for converting wind energy into electrical energy and transmitting it through transmission lines to the electrolyzer for water electrolysis to produce hydrogen. The transformer can be a double-winding transformer, and the phase shifter can be a rectifier phase-shifting transformer.

[0070] 4. Black start: This refers to the process of restarting a power system using its own backup power source or an independent power source when it completely loses external power. In off-grid wind power to hydrogen production systems, black start refers to restarting wind turbines, electrolyzers, and other equipment using a backup power source (such as a black start power source) after a complete power outage caused by a fault, natural disaster, or other reasons, thus restoring the system to normal operation. Black start power sources typically need to have sufficient capacity and stability to ensure reliable power support during system recovery.

[0071] 5. Power Flow Calculation: Used to determine the steady-state operation of a power system under given operating conditions. It analyzes the power flow of the power system by solving for parameters such as node voltage, current, and power distribution in the power network. In off-grid wind power to hydrogen production systems, power flow calculation can be used to analyze the operating parameters of the primary system during black start, such as the voltage, current, and power loss of each node, thus providing a basis for calculating the black start power supply capacity. Through accurate power flow calculation, it can be ensured that the black start power supply can meet the dynamic power consumption requirements of the primary system during system recovery, avoiding the impact of insufficient or excessive power supply capacity on system startup and operation.

[0072] The methods provided in the embodiments of this disclosure will now be described using several exemplary embodiments.

[0073] Please refer to Figure 1 This document illustrates a flowchart of a method for calculating the black start power capacity of an off-grid wind power hydrogen production system, provided in an exemplary embodiment of this disclosure. This embodiment uses the method in a computing device as an example for illustration. The method includes the following steps.

[0074] Step 101: Construct the equivalent circuit model of the primary system in the off-grid wind power hydrogen production system.

[0075] The primary system in an off-grid wind power hydrogen production system includes multiple primary devices, which may include DFIGs and other equipment, including one or more of transmission lines, transformers, and phase shifters.

[0076] The computing device constructs an equivalent circuit model of the primary system in an off-grid wind power hydrogen production system, which may include: constructing a unified branch model for each of the multiple primary devices, and integrating the unified branch models of the multiple primary devices to obtain the equivalent circuit model of the primary system.

[0077] The unified branch model of primary equipment is a simplified circuit model used to indicate the electrical characteristics of primary equipment. It simulates the behavior of primary equipment in a power system using equivalent model parameters (such as resistance, inductance, and capacitance).

[0078] The equivalent circuit model of a primary system is a simplified circuit model used to describe the electrical characteristics of the entire primary system. It integrates the unified branch models of multiple primary devices into a single overall circuit model for analyzing and calculating the performance of the primary system. In off-grid wind power to hydrogen production systems, the equivalent circuit model of the primary system can include equivalent circuit models of transmission lines, transformers, phase shifters, and DFIGs, etc. By constructing an equivalent circuit model, the electrical characteristics of the system under different operating conditions can be analyzed more intuitively, providing theoretical support for system planning, design, and operation management.

[0079] The construction of a unified branch model for each of the multiple primary devices may include: determining the electrical parameters of each primary device; determining the equivalent model parameters of the primary device based on the electrical parameters and the corresponding preset circuit model; and substituting the equivalent model parameters into the preset circuit model to obtain the unified branch model of the primary device.

[0080] Electrical parameters are descriptions of the actual physical characteristics of primary equipment and are fundamental data. Electrical parameters refer to physical quantities that describe the transmission, conversion, and distribution of electrical energy in primary equipment, and typically include resistance, inductance, capacitance, impedance, voltage, current, and power.

[0081] Equivalent model parameters are simplified parameters derived from electrical parameters, used to represent the characteristics of primary equipment in a unified branch model. These parameters simplify and abstract complex equipment characteristics using simple circuit elements (such as resistors, inductors, and capacitors) to facilitate analysis and calculation.

[0082] The preset circuit model is a framework structure. By substituting equivalent model parameters into it, a unified branch model for the primary equipment can be constructed. It should be noted that the construction process of the unified branch model for each primary equipment can be referred to the relevant descriptions in the following embodiments, and will not be described here.

[0083] Step 102: Perform power flow calculation based on the equivalent circuit model of the primary system to obtain the power flow calculation results. The power flow calculation results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system.

[0084] The computing equipment can perform power flow calculations based on the equivalent circuit model of the primary system using a preset power flow calculation algorithm, and obtain the power flow calculation results. These results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power-to-hydrogen system. These operating parameters may include the active and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage amplitude and phase of each node. The active and reactive power flowing through each branch reflects the power flow of each device and line in the primary system during the black start process. The voltage amplitude and phase of each node reflect the voltage level and synchronization status of the primary system.

[0085] The preset power flow calculation algorithm is a predefined algorithm used for power flow calculation. Common power flow calculation algorithms include the Gauss-Seidel iteration method and the Newton-Raphson method. These algorithms solve the power flow distribution of the power system through iterative calculation. For example, the Newton-Raphson method is an iterative algorithm that determines the power flow calculation result by iteratively solving a system of nonlinear equations. The basic steps of the Newton-Raphson method include, but are not limited to: 1. Initialization: Set initial values, such as the magnitude and phase angle of the node voltage. 2. Calculate the Jacobian matrix: Construct the Jacobian matrix based on the partial derivatives of the power flow equations. 3. Calculate the correction equation: Calculate the correction equation based on the Jacobian matrix and the residuals of the power flow equations. 4. Iterative solution: Solve the correction equation and update the magnitude and phase angle of the node voltage. 5. Convergence judgment: Check whether the iteration result meets the convergence condition (e.g., the residual is less than a certain threshold). 6. Output result: If the convergence condition is met, output the power flow calculation result; otherwise, return to step 2 to continue iterating. This embodiment of the invention does not limit the setting method of the power flow calculation algorithm.

[0086] Step 103: Determine the black start power supply capacity based on the power flow calculation results. The black start power supply capacity is the maximum power capacity required by the power supply during the black start process.

[0087] Black-start power supply capacity refers to the maximum power capacity required to restore power to an off-grid wind-to-hydrogen system after a complete power outage, ensuring the system can recover from a complete shutdown to normal operation. The power source may include energy storage batteries. Black-start power supply capacity can be determined based on the total active and reactive power required by the primary system to meet the power demands during startup.

[0088] In some embodiments, the computing device can, based on power flow calculation results, calculate the total active power and total reactive power required by all primary devices during the black start process. Total active power refers to the sum of the active power required by all primary devices in the primary system during the black start process. Active power is the actual power consumed and used for work (such as driving motors, heating, etc.). Total reactive power refers to the sum of the reactive power required by all primary devices in the primary system during the black start process. Reactive power is used to establish and maintain the magnetic field but does not perform actual work.

[0089] The calculation equipment can determine the black-start power supply capacity based on the total active and reactive power required by the primary system. The black-start power supply capacity should meet the active and reactive power requirements of the primary system to ensure a smooth black-start process. The black-start power supply capacity can be obtained by calculating the square root of the sum of the squares of the total active and reactive power required by the primary system. For safety, in practical applications, to further improve the reliability of the black-start process, a certain safety margin is usually added to the calculated black-start power supply capacity. It is generally recommended to increase the capacity by 10% to 20% to cope with possible unexpected situations and ensure the stability and safety of the black-start process.

[0090] In summary, this disclosure proposes a method for calculating the black-start power supply capacity of an off-grid wind power hydrogen production system. This method constructs an equivalent circuit model of the primary system in the off-grid wind power hydrogen production system, performs power flow calculations based on this model, and obtains the power flow calculation results. These results indicate the operating parameters of the primary system during the black-start process. By analyzing the dynamic power consumption characteristics of the primary system during black-start, this method can scientifically and accurately determine the maximum power capacity required by the black-start power supply. Compared to traditional methods relying on empirical estimation, this method significantly improves the scientific rigor and accuracy of capacity calculation, ensuring that the calculation results are closer to actual needs. Furthermore, this method effectively reduces resource waste caused by excessive reserve margins, thereby significantly reducing project investment costs and improving project economics. Simultaneously, accurate capacity calculation provides a reliable guarantee for the actual operation of the black-start power supply, ensuring that it can stably and reliably meet the demands during system startup, avoiding the impact of insufficient or excessive power capacity on system stability, and thus significantly improving the overall operational reliability of the off-grid wind power hydrogen production system.

[0091] Please refer to Figure 2 The diagram illustrates the electrical connections of an off-grid wind power hydrogen production system provided in an exemplary embodiment of this disclosure. The off-grid wind power hydrogen production system may include equipment such as a DFIG, converter, transformer, transmission lines, and electrolyzer. The following is a description of each device in the diagram:

[0092] 1. DFIG: It is the core component of a wind turbine generator set, used to convert wind energy into electrical energy.

[0093] 2. AC / DC and DC / AC converters: These converters are used to convert between alternating current (AC) and direct current (DC) to suit the needs of different devices.

[0094] 3. T1: Represents a transformer, used to adjust voltage to meet the power needs of the plant.

[0095] 4. Plant power: Provides power for equipment and operations within the wind farm.

[0096] 5. L1: Represents a power transmission line.

[0097] 6. T3 / T4: ​​Represents transformers, used to adjust voltage to meet the needs of auxiliary facilities, plant power, and electrolytic cells.

[0098] 7. AC / DC and DC / DC converters: Again used for voltage conversion to meet the needs of electrolytic cells.

[0099] 8. Electrolyzer: This is the core equipment in the hydrogen production process, which uses electrical energy to decompose water into hydrogen and oxygen.

[0100] 9. Public auxiliary facilities and plant power: Provide power for the public auxiliary facilities and internal power consumption of the hydrogen production plant.

[0101] Based on the following assumptions: 1. Power losses of DC / AC, DC / DC, AC / DC, and other converters are ignored; 2. Transmission lines are considered lossless lines, i.e., the line attenuation coefficient is 0; 3. Back-to-back wind turbine converters are considered ideal transformers. Figure 2 The electrical connection diagram shown can be abstracted into a power network topology diagram, such as... Figure 3 As shown in the diagram, this topology is a single-machine six-node system, meaning that the entire system has only one generator (i.e., DFIG) and six nodes (labeled as nodes ① to ⑥).

[0102] The energy storage battery is located at node ①, meaning it can convert direct current to alternating current via a DC / AC converter, and then connect to the 1140V AC line through transformer T1. This arrangement can be used for various purposes, including: 1. Power supply for wind farms; 2. Starting the transformer for a wind turbine; 3. Excitation of a wind turbine; 4. Charging transmission lines; 5. Starting the rectifier transformer for a hydrogen production unit; 6. Auxiliary and power supply for hydrogen production plants; 7. Low-power electrolysis power supply for a hydrogen production unit.

[0103] Nodes ① through ⑥ represent different components or connection points in a simplified power network topology diagram. The roles of these nodes in the system are as follows:

[0104] Node ①: This is the connection point of the energy storage battery. It converts direct current to alternating current through a DC / AC converter and connects to the AC power grid through transformer T1.

[0105] Node ②: This is the output of the DFIG. It converts AC power to DC power through an AC / DC converter, or converts DC power back to AC power through a DC / AC converter, to supply different loads.

[0106] Node ③: This is the output terminal of transformer T1, which adjusts the voltage to a level suitable for plant power supply.

[0107] Node ④: This is the other end of transmission line L1, which connects to transformers T3 / T4 for further power distribution.

[0108] Node ⑤: This is the output terminal of transformer T3, which provides power to auxiliary facilities and plant power.

[0109] Node 6: This is the output terminal of transformer T4, which supplies power to the electrolyzer for the hydrogen production process.

[0110] Pre-defined software packages (such as the Matpower package) can be used to perform power flow analysis calculations on off-grid wind power hydrogen production black start systems. During power flow analysis calculations, various primary equipment in the primary system (such as transformers, transmission lines, phase shifters, etc.) need to be modeled as a unified branch model so that the software package can process them. Figure 4 As shown. This includes:

[0111] 1. Transmission line section: including the series impedance Z of the transmission line. s =r s +jx s and total charging current b c , where r s x is the resistance of the transmission line. s For the inductive reactance of the transmission line, y s It is the admittance of the power transmission line.

[0112] 2. Transformer Section: The transformer has a turns ratio of N:1, representing the turns ratio of the primary winding to the secondary winding. The input voltage of the transformer is v. f The output voltage is v f / N. The input current of the transformer is i f The output current is N*i f Where τ is the turns ratio amplitude, θ shiftIt's the phase shift angle. The turns ratio determines the voltage ratio between the primary and secondary sides of the transformer, while the phase shift angle represents the phase shift of the voltage waveform. The transformer is located on the primary side (from bus), meaning the transformer's input terminal is connected to this node.

[0113] 3. Phase Shifter Section: Phase shifters are used to adjust the phase of the voltage. The diagram shows two phase shifters, each introducing a JB (Jack-Bauer) voltage. c A phase shift of 2 / 2.

[0114] To ensure consistency with the branch models of the aforementioned software packages, the following unified branch models for each primary device can be constructed for power flow calculations:

[0115] Transmission lines: The resistance, reactance, and susceptance parameters of transmission lines can be integrated into a preset circuit model to construct a unified branch model of the transmission line.

[0116] Two-winding transformer: This type of transformer has two windings, a primary side and a secondary side. A unified branch model of a two-winding transformer can be constructed based on its turns ratio and phase shift angle.

[0117] Phase shifter: A phase shifter is a device that can change the phase of a voltage. A unified branch model of the phase shifter can be constructed based on the phase shift angle of the phase shifter.

[0118] DFIG: A type of wind turbine that can control both active and reactive power. A unified branch model of DFIG can be constructed based on its characteristics.

[0119] The following section will introduce the construction process of the unified branch model for the four primary devices.

[0120] The unified branch circuit model of a transmission line is an equivalent circuit model used to simulate the electrical characteristics of transmission lines. This model simplifies the calculations of transmission lines in power system analysis by centrally representing characteristic parameters such as resistance, inductance, and capacitance. The process of constructing the unified branch circuit model of a transmission line includes, but is not limited to, the following steps:

[0121] 1. Determine the electrical parameters of the transmission line.

[0122] The electrical parameters of a transmission line include one or more of the following parameters: characteristic impedance, series impedance per unit length, parallel admittance per unit length, propagation constant, and length of the transmission line.

[0123] Characteristic impedance is an important parameter of transmission lines. It is a complex number that represents the total resistance of the transmission line to alternating current. When losses are ignored, characteristic impedance is a real number.

[0124] Series impedance per unit length represents the sum of resistance and reactance per unit length of a transmission line, and its unit is ohms per kilometer (Ω / km).

[0125] Parallel admittance per unit length represents the capacitive admittance per unit length of a transmission line, and the unit is Siemens per kilometer (S / km).

[0126] The propagation constant, comprising the phase constant and the attenuation constant, represents the propagation characteristics of electromagnetic waves in a transmission line. For a lossless line (i.e., an ideal line with no energy loss), the attenuation constant is 0. The phase constant is independent of the voltage level of the overhead line.

[0127] The length of a transmission line is its physical length, usually measured in kilometers (km) or meters (m).

[0128] 2. Determine the equivalent model parameters of the transmission line based on its electrical parameters and the corresponding preset circuit model.

[0129] The equivalent model parameters of a transmission line are parameters used to construct a unified branch model of the transmission line after certain mathematical transformations and simplifications of its electrical parameters. The equivalent model parameters of a transmission line include one or more of the following parameters: equivalent series resistance, equivalent series reactance, equivalent shunt susceptance, and equivalent time delay. The equivalent series resistance is an equivalent representation of the transmission line's resistance, reflecting its resistive losses. The equivalent series reactance is an equivalent representation of the transmission line's inductance, reflecting its inductive effect. The equivalent shunt susceptance is an equivalent representation of the transmission line's capacitance and conductance, reflecting its capacitive and conductive effects. The equivalent time delay is an equivalent representation of the transmission line's propagation time delay, reflecting the time required for a signal to propagate along the transmission line.

[0130] 3. Construct a unified branch model for transmission lines:

[0131] Substituting the equivalent model parameters of the transmission line into the corresponding preset circuit model of the transmission line, a unified branch model of the transmission line is obtained, which is used to describe the electrical characteristics of the transmission line.

[0132] For example, the unified branch model of a transmission line is a π-type unified branch model. The π-type unified branch model usually includes two π-type networks, which represent the series impedance and parallel admittance of the transmission line, respectively.

[0133] By following the steps described above, a unified branch circuit model of a transmission line can be constructed. This model can be used for power flow calculations and stability analysis of power systems. This model simplifies the analysis of transmission lines, making power system analysis more efficient and accurate.

[0134] In some embodiments, a schematic diagram of the unified branch model of a transmission line is shown below. Figure 5 As shown, where:

[0135]

[0136] in, Let be the series impedance of the transmission line, and let be the total impedance of the transmission line. The parallel admittance of the transmission line is expressed as the total admittance of the transmission line. R is the characteristic impedance of the transmission line, in Ω. For a typical transmission line, R << ωL. If losses are ignored, the characteristic impedance is a real number. z is the series impedance per unit length of the transmission line, in Ω / km. y is the parallel admittance per unit length of the transmission line, in s / km. γ is the propagation constant of the transmission line. For lossless lines, γ = jβ, where β is the phase constant, independent of the voltage level of the overhead line. The phase constant of a 50Hz transmission line is 0.00105 rad / km, and j is an imaginary unit. l is the length of the transmission line.

[0137] Expanding the two formulas above, we get:

[0138]

[0139] Where, x L1 b is the reactance per unit length of the transmission line. c Let be the susceptance per unit length of the transmission line. Corresponding to the unified branch model, the parameter expressions for the unified branch equivalent model of the transmission line can be obtained:

[0140]

[0141] Where, r s,L1 This is the series resistance of the transmission line; for lossless lines, this parameter is 0. s,L1 It is the series reactance of the transmission line. This is the parallel susceptance of the transmission line. τ is the time delay of the transmission line; for lossless lines, this parameter is 0.

[0142] The unified branch circuit model of a transformer is an equivalent circuit model used to simulate the electrical characteristics of a transformer. Taking a two-winding transformer as an example, its circuit model typically includes a leakage impedance branch and an excitation branch. Because the excitation impedance of the transformer's parallel branches is much larger than its leakage impedance, the current in the transformer's parallel branches is also relatively small, approximately 0.5% to 2% of the rated current. When calculating the steady-state power flow of a power system, the transformer's excitation admittance branch is often ignored, thus simplifying the calculation to a π-type per-unit equivalent circuit model of the transformer.

[0143] However, during the power flow calculation of the black-start steady-state process, the system is almost unloaded, and the inductive reactive power of the excitation admittance branch cannot be ignored in the overall system reactive power demand. Therefore, the embodiments of this disclosure adopt the following processing method: the excitation admittance branch is placed outside the π-type per-unit equivalent circuit model. After obtaining the π-type per-unit equivalent circuit model and its corresponding unified branch model, the excitation admittance branch is then connected to the corresponding node and treated as a parallel branch to ground. This processing method ensures both the simplification and efficiency of the model under normal operating conditions and the accuracy under special operating conditions such as black start. The process of constructing the unified branch circuit model of the transformer includes, but is not limited to, the following steps:

[0144] 1. Determine the electrical parameters of the transformer.

[0145] The electrical parameters of a transformer include one or more of the following parameters: turns ratio, impedance, inductive reactance, resistance, rated power, reference voltage, and current.

[0146] The turns ratio refers to the ratio of the number of turns in the primary winding to the number of turns in the secondary winding of a transformer. It determines the voltage transformation relationship of the transformer.

[0147] Impedance is a complex number that represents the phase relationship between voltage and current in an AC circuit. It includes resistance and inductive reactance.

[0148] Rated power refers to the maximum power that a transformer can continuously output under rated conditions, usually measured in watts (W) or kilovolt-amperes (kVA). Rated conditions include rated voltage, rated current, and rated frequency.

[0149] Reference voltage and current are values ​​used in transformer design and analysis. They are typically used to standardize transformer parameters for comparison and calculation. Reference values ​​can be actual operating values ​​or standard values ​​specified by the manufacturer.

[0150] 2. Determine the equivalent model parameters of the transformer based on its electrical parameters and the corresponding preset circuit model.

[0151] The equivalent model parameters of a transformer are calculated based on its electrical parameters and a pre-defined circuit model, and are used to simulate the behavior of the transformer in power system analysis. The equivalent model parameters of a transformer include one or more of the following parameters: equivalent series resistance, equivalent series reactance, turns ratio, and equivalent admittance.

[0152] Equivalent series resistance refers to the total resistance after the resistances of the primary and secondary sides of a transformer are converted to the primary side through the turns ratio.

[0153] Equivalent series reactance refers to the total reactance after converting the reactance of the primary and secondary sides of a transformer to the primary side through the turns ratio.

[0154] The turns ratio is the ratio of the number of turns in the primary winding to the number of turns in the secondary winding of a transformer, and it determines the voltage transformation ratio of the transformer.

[0155] Equivalent admittance refers to the parameter that simulates the admittance characteristics of a transformer in an equivalent circuit model; it is the reciprocal of the equivalent impedance.

[0156] 3. Construct a unified branch model for the transformer:

[0157] Substituting the equivalent model parameters of the transformer into the corresponding preset circuit model yields a unified branch model of the transformer, which is used to describe the electrical characteristics of the transformer.

[0158] In some embodiments, a schematic diagram of the unified branch circuit model of the transformer is shown below. Figure 6 As shown, where:

[0159]

[0160] Where y1, y2, and y3 are the three parts of the transformer's equivalent admittance. These are the per-unit values ​​of the turns ratio of the primary and secondary windings of the transformer. This refers to the rated turns ratio of the primary winding of the transformer. This refers to the rated turns ratio of the secondary winding of the transformer. This is the reference turns ratio for the primary winding of the transformer. This is the reference turns ratio for the secondary winding of the transformer.

[0161] For equivalent admittance, Equivalent impedance:

[0162]

[0163] in, The impedance of the primary side of the transformer. This is the impedance of the secondary side of the transformer. This represents the per-unit value of the turns ratio of the secondary winding of the transformer. Let i be the per-unit value of the impedance on the i-th side of the transformer. Let be the resistance of the i-th primary side of the transformer. Let be the inductive reactance of the i-th primary side of the transformer.

[0164] Expanding the above three formulas, we get:

[0165]

[0166] Where, n 1,pu n is the per-unit value of the number of turns on the primary side of the transformer. 2,puR1 is the per-unit value of the number of turns on the secondary side of the transformer, R2 is the resistance on the primary side of the transformer, X1 is the inductive reactance on the primary side of the transformer, and X2 is the inductive reactance on the secondary side of the transformer.

[0167] Written in matrix form:

[0168]

[0169] Where i1 is the primary current of the transformer, i3 is the secondary current of the transformer, v1 is the primary voltage of the transformer, v3 is the secondary voltage of the transformer, and R and X are the resistance and reactance, respectively.

[0170] Corresponding to the unified branch model, the parametric expression for the unified branch model of the transformer can be obtained:

[0171]

[0172] in, r is the equivalent series resistance between the primary and secondary sides of the transformer. σ1,pu r is the per-unit value of the primary leakage resistance of the transformer. σ2,pu This represents the per-unit value of the secondary leakage resistance of the transformer. x is the equivalent series reactance of the primary and secondary sides of the transformer. σ1,pu x is the per-unit value of the primary leakage inductance of the transformer. σ2,pu This is the per-unit value of the secondary leakage inductance of the transformer. The turns ratio of the transformer. This is the equivalent admittance of the transformer.

[0173] A unified branch circuit model of a phase shifter (also known as a phase-shifting transformer) is an equivalent circuit model used to simulate the electrical characteristics of a phase shifter. Taking a pulse rectifier phase-shifting transformer as an example, this type of transformer actually consists of two sets of three-winding phase-shifting transformers connected in parallel on the high-voltage side. On the low-voltage side, these four windings are not connected in parallel, but are arranged with phases differing by 15° sequentially. This design can effectively achieve voltage phase shifting to adapt to different rectification requirements. In some embodiments, the circuit diagram of a 24-pulse rectifier phase-shifting transformer is shown below. Figure 7 As shown in the figure, n represents the turns ratio of the phase-shifting transformer, and ∠(α-15°), ∠(α), ∠(α+15°), and ∠(α+30°) are the phase angles of the four windings on the low-voltage side of the phase-shifting transformer, which differ from each other by 15°.

[0174] The model of a three-winding phase-shifting transformer is complex, and the low-voltage side voltage is not the primary concern of the embodiments disclosed herein. Therefore, Figure 7The three-winding phase-shifting transformer shown is simplified to a two-winding phase-shifting transformer with two high-voltage sides connected in parallel. The two-winding phase-shifting transformer model can be represented by an ideal transformer with a complex ratio connected in series with admittance. The parallel admittance branch needs to be considered, and the treatment is the same as for the two-winding transformer model. A parallel branch to ground is added at nodes ⑤ and ⑥ to simulate the parallel admittance effect in the actual circuit. The simplified circuit diagram of the 24-pulse rectifier phase-shifting transformer is shown below. Figure 8 As shown in the figure. n in the figure T3 The rated capacity ratio of phase-shifting transformer T3, ∠(θ) T3,4 -θ T3,5 Y represents the phase difference between node ④ and node ⑤ on the high-voltage side of phase-shifting transformer T3. e,T3 For the equivalent admittance of phase-shifting transformer T3, Y m,T3 This is the excitation admittance of phase-shifting transformer T3. T4 The rated capacity ratio of phase-shifting transformer T4, ∠(θ) T4,4 -θ T4,6 Y represents the phase difference between nodes ④ and ⑥ on the high-voltage side of phase-shifting transformer T4. e,T4 For the equivalent admittance of phase-shifting transformer T4, Y m,T4 This is the excitation admittance of phase-shifting transformer T4.

[0175] The process of constructing a unified branch circuit model for a phase-shifting transformer includes, but is not limited to, the following steps:

[0176] 1. Determine the electrical parameters of the phase-shifting transformer.

[0177] The electrical parameters of a phase-shifting transformer include one or more of the following parameters: turns ratio, impedance, inductive reactance, and resistance.

[0178] 2. Determine the equivalent model parameters of the phase-shifting transformer based on its electrical parameters and the corresponding preset circuit model.

[0179] The equivalent model parameters of a phase-shifting transformer are calculated based on its electrical parameters and a pre-defined circuit model, and are used to simulate the behavior of the phase-shifting transformer in power system analysis. The equivalent model parameters of a phase-shifting transformer include one or more of the following parameters: equivalent series resistance, equivalent series reactance, turns ratio, and equivalent admittance.

[0180] 3. Construct a unified branch model for the phase-shifting transformer:

[0181] Substituting the equivalent model parameters of the phase-shifting transformer into the corresponding preset circuit model yields a unified branch model of the phase-shifting transformer, which is used to describe the electrical characteristics of the phase-shifting transformer.

[0182] The transfer admittance from the primary side to the secondary side is different from the transfer admittance from the secondary side to the primary side. Therefore, the admittance matrix of the phase-shifting transformer is asymmetrical and cannot be represented by a π-type equivalent circuit. Only the admittance matrix between two nodes can be written. The admittance matrix between node ④ and node ⑤ is as follows:

[0183]

[0184] in, Here is the admittance matrix of phase-shifting transformer T3. All are admittance matrices of phase-shifting transformer T3 elements, This represents the per-unit value of the number of turns on the primary side of phase-shifting transformer T3. Here is the per-unit value of the number of turns on the secondary side of phase-shifting transformer T3, Δθ 45 The phase difference between node ④ and node ⑤ The resistance on the primary side of phase-shifting transformer T3. This refers to the resistance on the secondary side of phase-shifting transformer T3. The inductive reactance of the primary side of phase-shifting transformer T3, This is the inductive reactance of the secondary side of phase-shifting transformer T3.

[0185] Similarly, the admittance matrix between node ④ and node ⑥ The elements are as follows:

[0186]

[0187] in, All are admittance matrices of phase-shifting transformer T4 elements, This represents the per-unit value of the number of turns on the primary side of phase-shifting transformer T4. This represents the per-unit value of the number of turns on the secondary side of phase-shifting transformer T4. The resistance on the primary side of phase-shifting transformer T4, This refers to the resistance on the secondary side of phase-shifting transformer T4. The inductive reactance of the primary side of phase-shifting transformer T4, This is the inductive reactance of the secondary side of phase-shifting transformer T4.

[0188] Corresponding to the unified branch model, the parametric expression for the unified branch model of the phase-shifting transformer can be obtained:

[0189]

[0190] in, n is the equivalent series resistance of the primary and secondary sides of the phase-shifting transformer. x,pu r is the rated capacity ratio of the phase-shifting transformer. σ1,pu r is the per-unit value of the primary leakage resistance of the phase-shifting transformer.σ2,pu This represents the per-unit value of the secondary leakage resistance of the phase-shifting transformer. x is the equivalent series reactance of the primary and secondary sides of the phase-shifting transformer. σ1,pu x is the per-unit value of the primary leakage inductance of the phase-shifting transformer. σ2,pu This is the per-unit value of the secondary leakage inductance of the phase-shifting transformer. The equivalent admittance of the phase-shifting transformer, n is the turns ratio of the phase-shifting transformer. 4,pu θ represents the rated capacity ratio of node ④ of the phase-shifting transformer, θ is the phase angle introduced by the phase-shifting transformer, and is the difference in voltage phase across the phase-shifting transformer. T,4 Let θ be the phase angle at node ④ of the phase-shifting transformer. T,x Let x be the phase angle of node x of the phase-shifting transformer.

[0191] The unified branch circuit model of a DFIG is an equivalent circuit model used to simulate the electrical characteristics of a DFIG. The process of constructing a unified branch circuit model of a DFIG includes, but is not limited to, the following steps:

[0192] 1. Determine the electrical parameters of the DFIG.

[0193] The electrical parameters of DFIG include one or more of the following parameters: stator resistance, rotor resistance, stator leakage reactance, rotor leakage reactance, and mutual inductance reactance.

[0194] Stator resistance is the resistance of the stator winding, rotor resistance is the resistance of the rotor winding, stator leakage reactance is the leakage reactance of the stator winding, rotor leakage reactance is the leakage reactance of the rotor winding, and mutual inductance is the mutual inductance between the stator and the rotor.

[0195] 2. Determine the equivalent model parameters of DFIG based on its electrical parameters and the corresponding preset circuit model.

[0196] The equivalent model parameters of a DFIG are calculated based on its electrical parameters and a pre-defined circuit model, and are used to simulate the behavior of a DFIG in power system analysis. The equivalent model parameters of a DFIG include one or more of the following parameters: the equivalent impedance on the rotor side of the DFIG, the equivalent impedance on the stator side of the DFIG, and the equivalent impedance of a back-to-back converter.

[0197] The equivalent impedance of the rotor side of a DFIG includes the combination of rotor resistance and rotor leakage reactance, reflecting the total impedance of the rotor side to current. The equivalent impedance of the stator side of a DFIG includes the combination of stator resistance and stator leakage reactance, reflecting the total impedance of the stator side to current. The equivalent impedance of a back-to-back converter is the equivalent impedance of the back-to-back converter (including grid-side and machine-side converters), reflecting the converter's impedance to current.

[0198] 3. Construct a unified branch model for DFIG:

[0199] Substituting the equivalent model parameters of DFIG into the corresponding preset circuit model yields the unified branch model of DFIG, which is used to describe the electrical characteristics of DFIG.

[0200] When performing power flow calculations on power systems containing a DFIG (Dynamic Power Grid Injection), a suitable DFIG static model is first required. To this end, two modeling methods for using asynchronous wind turbines in power flow calculations are proposed: one method models the asynchronous wind turbine as a PQ node, where the PQ node is the active and reactive power control node, controlling the output of active and reactive power. The active power is determined based on wind speed and slip, and then... Figure 9 The steady-state model of the asynchronous motor shown is used to solve for the expression of reactive power with respect to active power, thereby determining the active and reactive power at this node. In the figure, V represents the stator terminal voltage, and I... R R is the current flowing through the stator resistor. s R is the stator resistance. R Let j be the rotor resistance, j(X1+X2) be the total reactance on the stator side, jXc be the compensation reactance, and jX be the rotor resistance. m For mutual inductance reactance. Another approach is to model the asynchronous wind turbine as an RX node, where an RX node is a node in which resistance and reactance are specified.

[0201] Furthermore, a novel method for PQ node modeling is proposed, which transforms the T-type equivalent circuit into an equivalent circuit in the form of a current source with parallel conductance. For example... Figure 10 As shown, the DFIG equivalent current source can calculate the active and reactive power injected into the grid by the stator based on the mechanical power of the wind turbine blades. Z in the figure... b Z is the equivalent impedance of the back-to-back converter. a Z is the equivalent impedance on the stator side of the DFIG. c Let P be the equivalent impedance on the rotor side of the DFIG, P be the active power output from the DFIG, and Q be the reactive power output from the DFIG.

[0202] During black start, the stator of the DFIG is in an open-circuit state, while the rotor side is connected to the microgrid via back-to-back converters. Due to the decoupling effect of the DC bus capacitor, the power changes of the generator-side converters and stator / rotor cannot be sensed from the grid side; active and reactive power can only be exchanged with the grid-side converters in the back-to-back converters. During this process, the active power of the DFIG node mainly consists of converter switching losses, which can be considered a constant value during startup. The reactive power injected into the grid by the node is typically set to zero under the action of the back-to-back converters. Therefore, although the DFIG can be considered as a PQ node connected to the microgrid AC bus via a fundamental frequency impedance during black start, its physical meaning is completely different from that of a DFIG node during normal grid-connected operation.

[0203] Integrating the four unified branch models constructed above yields the equivalent circuit model of the primary system. Illustratively, the four unified branch models constructed above are added to... Figure 3 The power network topology diagram shown yields an equivalent circuit model of the primary system for power flow calculations. Branch numbers are defined, and the positive direction of series branches is specified as pointing from the largest number to the smallest. A schematic diagram of the equivalent circuit model of the primary system is shown below. Figure 11 As shown. Where, P x Let Q be the active power at node x. x Let y be the reactive power at node x. mn,Xx Let X represent the admittance between node m and node n, X represent branch elements, T represent transformers, and L represent transmission lines. T2 specifically refers to the DFIG branch, and x represents the serial number, such as T1 being transformer number 1.

[0204] This is an illustrative example of how the initial bus parameters are set. Figure 12 As shown in the image. The following is an analysis of the content in the image:

[0205] Node types include: vθ (voltage and phase angle control node), PV (voltage control node), and PQ (active and reactive power control node).

[0206] Parameter Description: Active Power Demand (MW): Represents the active power required by the node. Reactive Power Demand (MVar): Represents the reactive power required by the node. Voltage Baseline (kV): Represents the voltage baseline value of the node. Voltage Amplitude (pu): Represents the voltage amplitude of the node, expressed in per-unit value. Voltage Phase Angle (deg): Represents the voltage phase angle of the node. Parallel Active Power Consumption (MW): Represents the active power consumed by parallel branches. Parallel Reactive Power Injection (MVar): Represents the reactive power injected by parallel branches.

[0207] (1) Power requirements of node ①: This node is connected to the power supply of the wind farm control system. It is assumed that the required active power is 5% of the rated power of one wind turbine, i.e., 0.25MW. Assuming the power factor is 0.9, the required reactive power is 0.125MVar.

[0208] (2) Power requirements of nodes ⑤ and ⑥: Both nodes are connected to the public auxiliary equipment of the hydrogen production plant, and the public auxiliary power is shared equally between the two nodes. The black start process only considers the minimum electrical equipment that must be started, so domestic electricity consumption is not considered. The public auxiliary power consumption is 0.25MW / 1000Nm3. Assuming a power factor of 0.9, the total reactive power required is 0.125Mvar.

[0209] (3) Transformer parameters: The no-load loss of the transformer is taken as 12kW, and the per-unit value of the no-load current is 0.85%. The no-load loss is the active power consumed by the parallel branch. The reactive power injected by the parallel branch needs to be calculated based on the per-unit value of the no-load current.

[0210] Calculate the magnetizing susceptance of the injected reactive power. The per-unit admittance value is:

[0211]

[0212] The high-voltage side admittance baseline value is:

[0213]

[0214] The actual admittance value converted to the high-voltage side is:

[0215] B m =0.0085 × 4.08 × 10 -3 =3.468×10 -5 S

[0216] The reactive power injected into the power grid is:

[0217] Q sh =-U 2 B m =-35000 2 ×3.468×10 -5 = -0.042MVar

[0218] This is an illustrative example of how the generator's initial parameters are set. Figure 13 As shown, the line parameters are set as follows: Figure 14 As shown in the figure. The following is an explanation of the parameters in the figure:

[0219] 1. Parameters r, x, and b represent the resistance, reactance, and susceptance in the unified branch model, respectively.

[0220] 2. The parameter ratio is the non-standard turns ratio of the transformer. When the parameter ratio is "from bus", it means that the impedance is on the "to bus" side; when the parameter ratio = 0, it means that the branch is a transmission line and there is no transformer.

[0221] 3. The parameter angle is the phase shift angle of the phase shifter branch (in degrees). A positive value indicates that the phase angle of "from bus" lags behind that of "to bus".

[0222] 4. In the example, the LGJQ-300 35kV overhead line can be used. The three-phase conductors are arranged in an equilateral triangle, with a conductor spacing of 3m and a transmission distance of 10km. Typical parameters (per unit value) are: x L =0.3595Ω / km, b L =3.06×10 -6 S / km, at (35kV) 2 The per-unit value based on / 100MVA=12.25Ω is:

[0223] 5. Assume transformer T1 has a standard turns ratio, model SFZL-10000, and its per-unit reactance is 0.750 ohms and its per-unit resistance is 0.088 ohms.

[0224] 6. Assuming the DFIG slip is at its rated value in steady state, take a 2MW doubly-fed generator as an example. The stator resistance is 0.0344pu, the stator leakage reactance is 0.2748pu, the rotor resistance is 0.0273pu, and the rotor leakage reactance is 0.3979pu.

[0225] An illustrative diagram of the power flow calculation results is shown below. Figure 15 As shown below. The following is an analysis of the power flow calculation results:

[0226] During the steady-state process of black start, the energy storage system injects 0.53 MW of active power into the grid. This power mainly consists of control power from wind power and hydrogen production plants, and also includes transmission line losses and transformer winding resistance losses. The energy storage system injects 0.34 MVar of inductive reactive power into the grid.

[0227] The following points can be observed from the diagram: 1. In the double-winding transformer branches ①-③, the transformer's magnetizing conductance causes an active power loss of 10kW, while the magnetizing susceptance consumes 0.04MVar of reactive power. 2. In the transmission line branches ③-④, the charging reactive power of the transmission line is 0.03MVar. 3. In the phase-shifting transformer branches ④-⑤ and ④-⑥, the inductive reactive power consumed by the magnetizing susceptance of each transformer is 0.04MVar.

[0228] By employing appropriate modeling methods for power flow calculations, the voltage at each node and the power flow in each branch of an off-grid wind-to-hydrogen system during black start can be determined. This facilitates a direct analysis of the active and reactive power demands of each component in the system. The calculation results can provide guidance for the design of black start power supply capacity in engineering projects.

[0229] In summary, the method provided in this disclosure, on the one hand, can accurately predict the operating parameters of the primary system during black start by constructing an equivalent circuit model and performing power flow calculations, thereby more accurately determining the required power supply capacity. This method helps optimize the design of black start power supplies, ensuring that the power supply capacity meets start-up requirements without over-configuration, thus saving costs. Accurate calculation of power supply capacity improves the reliability of system startup and reduces the risk of startup failure due to insufficient power supply capacity. On the other hand, by constructing a unified branch model, the complex primary system can be decomposed into multiple modules, facilitating individual analysis and optimization of each device. The construction of the unified branch model allows for easy integration of models of different devices to form a complete equivalent circuit model of the primary system. Furthermore, it covers various devices such as DFIGs, transmission lines, transformers, and phase shifters, making the model more comprehensive and practical. This method is applicable to complex systems containing multiple primary devices, improving the applicability and accuracy of the model. Moreover, by determining the electrical parameters and equivalent model parameters of each device, a unified branch model can be constructed more accurately, improving the model's accuracy. This method provides a standardized modeling process, helping to unify the construction methods of different device models and facilitating model comparison and analysis. On the other hand, power flow calculations provide detailed information on active power, reactive power, voltage amplitude, and phase, facilitating a comprehensive understanding of the system's operating status. This detailed information can be used to diagnose potential problems in the system and optimize system configuration and operating strategies. Furthermore, by calculating the total active and reactive power required by the system in a single operation, the black-start power supply capacity can be determined more accurately. This method helps avoid over-configuring power supply capacity, thereby saving costs while ensuring reliable system startup.

[0230] The following are device embodiments of the present disclosure. For parts not described in detail in the device embodiments, please refer to the technical details disclosed in the above method embodiments.

[0231] This disclosure provides a black start power capacity calculation device for an off-grid wind power hydrogen production system. This device, referred to as a computing device, can be implemented entirely or partially through software, hardware, or a combination of both. The device includes: a construction module, a calculation module, and a determination module.

[0232] The building module is used to construct the equivalent circuit model of the primary system in an off-grid wind power hydrogen production system;

[0233] The calculation module is used to perform power flow calculations based on the equivalent circuit model of the primary system and obtain the power flow calculation results. The power flow calculation results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system.

[0234] The determination module is used to determine the black-start power supply capacity based on the power flow calculation results. The black-start power supply capacity is the maximum power capacity required by the power supply during the black-start process.

[0235] In one possible implementation, the primary system includes multiple primary devices, building modules, and is also used for:

[0236] Construct a unified branch model for each of the multiple primary devices. The unified branch model is used to indicate the electrical characteristics of the primary devices.

[0237] By integrating the unified branch models of multiple primary devices, the equivalent circuit model of the primary system is obtained.

[0238] In another possible implementation, multiple primary devices include DFIGs and other devices, including one or more of transmission lines, transformers, and phase shifters.

[0239] In another possible implementation, the building module is also used for:

[0240] For each primary device, determine its electrical parameters;

[0241] Based on the electrical parameters of the primary equipment and the corresponding preset circuit model, determine the equivalent model parameters of the primary equipment;

[0242] Substituting the equivalent model parameters into the preset circuit model yields a unified branch model for the primary equipment.

[0243] In another possible implementation, the power flow calculation results include the active and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage magnitude and phase of each node.

[0244] In another possible implementation, the determining module is also used for:

[0245] Based on the power flow calculation results, determine the total active power and total reactive power required by the primary system during the black start process;

[0246] The black-start power supply capacity is determined based on the total active power and total reactive power required by the primary system.

[0247] It should be noted that the above embodiments only illustrate the division of the above functional modules when implementing the device. In actual applications, the above functions can be assigned to different functional modules according to actual needs, that is, the content structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0248] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0249] This disclosure also provides a black start power capacity calculation device for an off-grid wind power hydrogen production system, including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the above method.

[0250] This disclosure also provides a non-volatile computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above-described method.

[0251] This disclosure also provides a computer program product, including a computer program or a non-volatile computer-readable storage medium carrying the computer program, wherein the computer program implements the steps of the above method when executed by a processor.

[0252] Figure 16 This is a block diagram illustrating an apparatus 1900 according to an exemplary embodiment. For example, apparatus 1900 may be provided as a computing device, which may be a server or a terminal device. (Refer to...) Figure 16 The apparatus 1900 includes a processing component 1922, which further includes one or more processors, and memory resources represented by memory 1932 for storing instructions, such as application programs, that can be executed by the processing component 1922. The application programs stored in memory 1932 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 1922 is configured to execute instructions to perform the methods described above.

[0253] Device 1900 may also include a power supply component 1926 configured to perform power management of device 1900, a wired or wireless network interface 1950 configured to connect device 1900 to a network, and an input / output interface 1958 (I / O interface). Device 1900 can operate on an operating system stored in memory 1932, such as Windows Server™, MacOS X™, Unix™, Linux™, FreeBSD™, or similar.

[0254] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 1932 including computer program instructions that can be executed by a processing component 1922 of the device 1900 to perform the above-described method.

[0255] Computer-readable storage media can be tangible devices capable of holding and storing programs / instructions used by instruction execution devices. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0256] The computer program (or computer-readable program instructions) described herein can be downloaded from a computer-readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage medium in the respective computing / processing device.

[0257] The computer program (or computer program instructions) used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuits, such as programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), are personalized by utilizing state information of computer-readable program instructions. These electronic circuits can execute computer-readable program instructions to implement various aspects of this disclosure.

[0258] Various aspects of this disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should 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-readable program instructions.

[0259] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0260] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0261] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0262] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for calculating the black start power capacity of an off-grid wind power hydrogen production system, characterized in that, The method includes: Construct an equivalent circuit model of the primary system in the off-grid wind power hydrogen production system; Power flow calculations are performed based on the equivalent circuit model of the primary system to obtain power flow calculation results. The power flow calculation results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system. The power flow calculation results include the active power and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage amplitude and phase of each node. Based on the power flow calculation results, the black start power supply capacity is determined, which is the maximum power capacity required by the power supply during the black start process. The step of determining the black-start power supply capacity based on the power flow calculation results includes: Based on the power flow calculation results, determine the total active power and total reactive power required by the primary system during the black start process; The black-start power supply capacity is determined based on the total active power and total reactive power required by the primary system. The primary system includes a doubly-fed induction generator (DFIG), transmission lines, transformers, and phase shifters. Constructing the equivalent circuit model of the primary system in the off-grid wind power hydrogen production system includes: For the DFIG, an equivalent circuit model in the form of parallel current source conductance is adopted, and the DFIG is regarded as a PQ node during black start. The active power of the DFIG is set to a constant value of converter loss, and the reactive power is set to 0. For the transmission line, a π-type unified branch model is adopted, which includes series impedance and parallel admittance; For the transformer, a π-type per-unit equivalent circuit model is adopted, and the excitation admittance branch is treated as a parallel branch to ground. For the phase shifter, a unified branch model in the form of an asymmetric admittance matrix is ​​adopted.

2. The method according to claim 1, characterized in that, The primary system includes multiple primary devices, and constructing the equivalent circuit model of the primary system in the off-grid wind power hydrogen production system includes: Construct a unified branch model for each of the multiple primary devices, the unified branch model being used to indicate the electrical characteristics of the primary devices; The unified branch models of the multiple primary devices are integrated to obtain the equivalent circuit model of the primary system.

3. The method according to claim 2, characterized in that, The construction of the unified branch model for each of the multiple primary devices includes: For each of the primary devices, determine the electrical parameters of the primary device; Based on the electrical parameters of the primary equipment and the corresponding preset circuit model, determine the equivalent model parameters of the primary equipment; Substituting the equivalent model parameters into the preset circuit model yields the unified branch model of the primary equipment.

4. A black start power supply capacity calculation device for an off-grid wind power hydrogen production system, characterized in that, The device includes: The construction module is used to construct the equivalent circuit model of the primary system in the off-grid wind power hydrogen production system; The calculation module is used to perform power flow calculation based on the equivalent circuit model of the primary system to obtain power flow calculation results. The power flow calculation results are used to indicate the operating parameters of the primary system during the black start process of the off-grid wind power hydrogen production system. The power flow calculation results include the active power and reactive power flowing through each branch in the equivalent circuit model, as well as the voltage amplitude and phase of each node. The determination module is used to determine the black-start power supply capacity based on the power flow calculation results, wherein the black-start power supply capacity is the maximum power capacity required by the power supply during the black-start process; The determining module is further configured to: Based on the power flow calculation results, determine the total active power and total reactive power required by the primary system during the black start process; The black-start power supply capacity is determined based on the total active power and total reactive power required by the primary system. The primary system includes a doubly-fed induction generator (DFIG), transmission lines, a transformer, and a phase shifter. The building module is also used for: For the DFIG, an equivalent circuit model in the form of parallel current source conductance is adopted, and the DFIG is regarded as a PQ node during black start. The active power of the DFIG is set to a constant value of converter loss, and the reactive power is set to 0. For the transmission line, a π-type unified branch model is adopted, which includes series impedance and parallel admittance; For the transformer, a π-type per-unit equivalent circuit model is adopted, and the excitation admittance branch is treated as a parallel branch to ground. For the phase shifter, a unified branch model in the form of an asymmetric admittance matrix is ​​adopted.

5. A black start power supply capacity calculation device for an off-grid wind power hydrogen production system, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 3.

6. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

7. A computer program product comprising a computer program, or a non-volatile computer-readable storage medium carrying a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

Images