Valuing method for amplitude limiting current phase angle of voltage source type converter and related product
By calculating the value range and optimal value of the current phase angle, the problem of insufficient current phase angle in the prior art is solved, and the inverter can automatically withdraw from the limiting control after limiting, and resume normal operation. Obtain maximum extreme resection time.
Patent Information
- Application Number
- CN202411625764.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-02-14
AI Technical Summary
The existing voltage-source inverter limiting control methods cannot effectively obtain the value range and optimal value of the current phase angle, resulting in poor limiting effect.
By designing the value method of the current phase angle, the value range and optimal value of the current phase angle after the limiting of the voltage source converter is calculated and determined, including obtaining the active power reference value of the inverter, the connection point voltage and the power grid. The effective value of the voltage, the maximum allowable value of the output current and the equivalent reactance, and then calculate the minimum value, maximum value, limit cutting angle and limit cutting time of the current phase angle after limiting, and finally obtain the optimal value.
Ensure that the current phase angle after limiting is within the specified range, the inverter can automatically withdraw from the limiting control, restore normal operation, and obtain the maximum limit removal work angle and limit removal time.
Smart Images
Figure CN119448749A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of voltage source converters, and more particularly to a method for determining a phase angle of a limiting current of a voltage source converter and related products. Background Art
[0002] Currently, renewable energy sources such as wind power and photovoltaics are mostly integrated into the AC grid via voltage source converters. Voltage source converters, primarily composed of power electronic components, have far lower current capacity than synchronous generators. Therefore, a current limiter is required in the controller to limit the output current and prevent damage to the power electronic components.
[0003] Existing current limiting control methods can be mainly divided into virtual impedance limiting method and direct current limiting method. The virtual impedance limiting method reduces the voltage at the grid connection point of the converter by introducing virtual impedance, thereby limiting the output current of the converter. It can maintain the voltage source characteristics of the converter under fault conditions. Therefore, the transient stability of this limiting method is good, but the limiting effect is poor. The direct current limiting method limits the output current of the converter by limiting the amplitude of the current reference value, and has a good limiting effect. However, the traditional direct current limiting method usually only limits the current amplitude, and there is no method for determining the value of the current phase angle, so it is impossible to obtain the value range and optimal value of the current phase angle.
[0004] Therefore, there is an urgent need for a method for determining the phase angle of the limiting current of a voltage source converter and related products to solve the above problems. Summary of the Invention
[0005] The purpose of this application is to provide a method for determining the current phase angle of a voltage source converter and related products, so as to solve the problem that the traditional direct current limiting method does not have a method for determining the current phase angle, and cannot obtain the value range and optimal value of the current phase angle; this application designs a method for determining the current phase angle, and calculates and determines the value range and optimal value of the current phase angle after the voltage source converter is limited.
[0006] The present application provides a method for obtaining the phase angle of the limited current of a voltage source converter, comprising: S1, obtaining a reference value of the active power of the converter, obtaining the effective value of the voltage at the grid connection point of the converter and the grid voltage, obtaining the maximum allowable value of the output current of the converter, and obtaining the equivalent reactance between the converter and the grid connection line; S2, calculating the maximum allowable value of the output active power of the converter in normal operation and limited operation; S3, calculating the minimum and maximum values of the output current phase angle of the converter after limiting, and obtaining the phase angle of the output current after limiting. The value range of the converter output current phase angle; S4, calculate the power angle of the converter stable operating point and the power angle of the converter unstable operating point after limiting; S5, calculate the limit cut-off angle corresponding to the converter output current phase angle after limiting according to the equal area rule; S6, calculate the limit cut-off time of the converter output current after limiting according to the limit cut-off angle of the converter output current phase angle after limiting; S7, compare the limit cut-off time corresponding to the converter output current phase angle after limiting, and obtain the optimal value of the converter output current phase angle after limiting.
[0007] In one possible implementation, S2, calculates the maximum allowable value of the output active power of the converter in normal operation and limited operation; including: calculating the maximum allowable value of the output active power of the converter in normal operation based on the grid voltage and the effective value of the voltage at the converter grid connection point, and the equivalent reactance between the converter and the grid connection line; calculating the maximum allowable value of the output active power in the limited operation state based on the maximum allowable output current of the converter and the effective value of the voltage at the converter grid connection point.
[0008] In one possible implementation, S3, calculates the minimum and maximum values of the phase angle of the converter output current after limiting, and obtains the value range of the phase angle of the converter output current after limiting; including: calculating the minimum and maximum values of the phase angle of the converter output current after limiting based on the active power reference value of the converter, the maximum allowable value of the output active power under the limiting operation state, the effective value of the grid voltage and the converter grid connection point voltage, the maximum allowable value of the converter output current, and the equivalent reactance between the converter and the grid connection line.
[0009] In one possible implementation, S4, calculating the power angle of the converter's stable operating point and the power angle of the converter's unstable operating point after limiting; including: calculating the power angle of the converter's stable operating point based on the converter's active power reference value and the maximum allowable value of the output active power under normal operating conditions; calculating the power angle of the converter's unstable operating point after limiting based on the converter's active power reference value and the maximum allowable value of the output active power under limited operating conditions.
[0010] In one possible implementation, S5, calculating the limit resection angle corresponding to the output current phase angle of the converter after limiting according to the equal area rule; including: calculating the limit resection angle corresponding to the output current phase angle of the converter after limiting according to the active power reference value of the converter, the power angle of the stable operating point of the converter, the power angle of the unstable operating point of the converter after limiting, the maximum allowable value of the output active power under the limited operating state and the output current phase angle of the converter.
[0011] In one possible implementation, S6, based on the limit cut-off angle of the converter output current phase angle after limiting, calculates the limit cut-off time of the converter output current after limiting; including: based on the inertia constant of the converter, the limit cut-off angle corresponding to the converter output current phase angle after limiting, the power angle of the converter stable operating point, the grid reference angular velocity and the converter active power reference value, calculates the limit cut-off time corresponding to the converter output current phase angle.
[0012] In one possible implementation, S7, compares the limit cut-off time corresponding to the phase angle of the converter output current after limiting to obtain the optimal value of the phase angle of the converter output current after limiting; including: calculating the optimal value of the phase angle of the converter output current after limiting based on the maximum value of the limit cut-off time corresponding to the phase angle of the converter output current.
[0013] The present application provides a computer device, which includes: a memory and a processor, wherein the processor is configured to execute a computer program stored in the memory, so that the computer device executes the above-mentioned method for determining the phase angle of the limiting current of a voltage source converter.
[0014] The present application provides a computer storage medium, characterized in that it includes computer instructions. When the computer instructions are executed on a computer device, the computer device executes the above-mentioned method for determining the phase angle of the limiting current of a voltage source converter.
[0015] The present application provides a computer program product, characterized in that when the computer program product is run on a computer device, the computer device is enabled to execute the above-mentioned method for determining the phase angle of the limiting current of a voltage source converter.
[0016] Compared with the prior art, the present application has the following beneficial effects: the present application determines the value range of the converter current phase angle after limiting, which can ensure that when the converter current phase angle after limiting is within the value range, the converter can autonomously exit the current limiting control and restore normal operation after the fault is cut off under various working conditions; it further determines the optimal value of the converter current phase angle after limiting, which can ensure that under the optimal value condition of the converter current phase angle after limiting, the converter obtains the maximum limit cut-off power angle and limit cut-off time. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:
[0018] Figure 1 A flow chart of a method for determining the phase angle of the limiting current of a voltage source converter provided in an embodiment of the present application;
[0019] Figure 2 A comparison chart of simulation verification provided for the embodiments of this application;
[0020] Figure 3 A diagram of the structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0021] Hereinafter, the terms "include" or "may include" as used in various embodiments of the present application indicate the presence of the claimed function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing or the possibility of adding one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing.
[0022] The terms used in the various embodiments of the application are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art of the application. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having idealized meaning or too formal meaning, unless clearly defined in the various embodiments of the application.
[0023] In order to make the objectives, technical solutions and advantages of this application more clear, the present application is further described in detail below in conjunction with examples and drawings. The schematic implementation methods of this application and their descriptions are only used to explain this application and are not intended to limit this application.
[0024] See Figure 1 As shown, Figure 1This is a flow chart of a method for determining the phase angle of the limiting current of a voltage source converter provided in an embodiment of the present application. The method includes: S1, obtaining a reference value of the active power of the converter, obtaining the effective value of the voltage at the grid connection point of the converter and the grid voltage, obtaining the maximum allowable value of the output current of the converter, and obtaining the equivalent reactance between the converter and the grid connection line; S2, calculating the maximum allowable value of the output active power of the converter under normal operating conditions and limited operating conditions; S3, calculating the minimum and maximum values of the output current phase angle of the converter after limiting, and obtaining the value range of the output current phase angle of the converter after limiting; S4, calculating the power angle of the stable operating point of the converter and the power angle of the unstable operating point of the converter after limiting; S5, calculating the limit cut-off angle corresponding to the output current phase angle of the converter after limiting according to the equal area rule; S6, calculating the limit cut-off time of the output current of the converter after limiting according to the limit cut-off angle of the output current phase angle of the converter after limiting; S7, comparing the limit cut-off time corresponding to the output current phase angle of the converter after limiting, and obtaining the optimal value of the output current phase angle of the converter after limiting.
[0025] The improvement of the present application lies in that the present application determines the value range and optimal value of the current phase angle after the converter is limited by calculation, thereby ensuring that the converter will not fall into a state where it cannot autonomously exit the limiting control mode due to improper current phase angle value within this range; at the same time, the optimal value of the current phase angle after the converter is limited is calculated, and under the optimal value condition, the converter obtains the maximum limit cut-off angle and the maximum limit cut-off time.
[0026] In one possible implementation, S2, calculates the maximum allowable value of the output active power of the converter in normal operation and limited operation; including: calculating the maximum allowable value of the output active power of the converter in normal operation based on the grid voltage and the effective value of the voltage at the converter grid connection point, and the equivalent reactance between the converter and the grid connection line; calculating the maximum allowable value of the output active power in the limited operation state based on the maximum allowable output current of the converter and the effective value of the voltage at the converter grid connection point.
[0027] Specifically, the maximum allowable value of the active power output under normal operating conditions is P max And the maximum allowable value of output active power under limited operation state The calculation formula is as follows:
[0028]
[0029] Among them, U s and U g are the effective values of the grid voltage and the converter connection point voltage, respectively, X line is the equivalent reactance between the converter and the grid connection line, I maxThe maximum allowable output current of the converter can be obtained by the above calculation, which can determine the active power limit that the converter can transmit in normal operation and limited operation.
[0030] In one possible implementation, S3, calculates the minimum and maximum values of the phase angle of the converter output current after limiting, and obtains the value range of the phase angle of the converter output current after limiting; including: calculating the minimum and maximum values of the phase angle of the converter output current after limiting based on the active power reference value of the converter, the maximum allowable value of the output active power under the limiting operation state, the effective value of the grid voltage and the converter grid connection point voltage, the maximum allowable value of the converter output current, and the equivalent reactance between the converter and the grid connection line.
[0031] Specifically, the minimum value of the phase angle of the converter output current after limiting is θ min The formula is as follows:
[0032]
[0033] Among them, P ref The above calculation can be used to determine the minimum allowable value of the converter output current phase angle.
[0034] The maximum value of the converter output current phase angle after limiting θ max The formula is as follows:
[0035]
[0036] Through the above calculation, the maximum allowable phase angle of the converter output current after limiting can be obtained.
[0037] The range of the phase angle of the converter output current after limiting (θ min ,θ max )as follows:
[0038]
[0039] When the output current phase angle of the converter is within this value range, it can ensure that the converter can autonomously exit the limiting control mode and resume normal operation after the fault is removed under various working conditions.
[0040] In one possible implementation, S4, calculating the power angle of the converter's stable operating point and the power angle of the converter's unstable operating point after limiting; including: calculating the power angle of the converter's stable operating point based on the converter's active power reference value and the maximum allowable value of the output active power under normal operating conditions; calculating the power angle of the converter's unstable operating point after limiting based on the converter's active power reference value and the maximum allowable value of the output active power under limited operating conditions.
[0041] Specifically, the converter stable operating point power angle δ0 and the converter unstable operating point power angle δ after limiting are lim The calculation method is as follows:
[0042]
[0043] Through the above calculation, the power angle of the converter's stable operating point and the power angle of the unstable operating point after limiting can be obtained.
[0044] In one possible implementation, S5, calculating the limit resection angle corresponding to the output current phase angle of the converter after limiting according to the equal area rule; including: calculating the limit resection angle corresponding to the output current phase angle of the converter after limiting according to the active power reference value of the converter, the power angle of the stable operating point of the converter, the power angle of the unstable operating point of the converter after limiting, the maximum allowable value of the output active power under the limited operating state and the output current phase angle of the converter.
[0045] Specifically, the equal area rule is used to obtain the limit cut-off angle δ corresponding to the output current phase angle of the converter after limiting: cut The calculation method is as follows:
[0046]
[0047] Among them, δ0 is the power angle of the converter stable operating point, δ lim is the unstable operating point power angle, and θ is the converter output current phase angle. Through the above calculation, the limit cut-off angle corresponding to the converter output current phase angle after limiting can be obtained.
[0048] In one possible implementation, S6, based on the limit cut-off angle of the converter output current phase angle after limiting, calculates the limit cut-off time of the converter output current after limiting; including: based on the inertia constant of the converter, the limit cut-off angle corresponding to the converter output current phase angle after limiting, the power angle of the converter stable operating point, the grid reference angular velocity and the converter active power reference value, calculates the limit cut-off time corresponding to the converter output current phase angle.
[0049] Specifically, the limit switching time t corresponding to the converter output current phase angle is cut The calculation formula is as follows:
[0050]
[0051] Where H is the inertia constant of the converter, δ cut is the limit cut-off angle corresponding to the converter output current phase angle, and ω0 is the grid reference angular velocity. Through the above calculation, the limit cut-off time corresponding to the converter output current phase angle after limiting can be obtained.
[0052] In one possible implementation, S7, compares the limit cut-off time corresponding to the phase angle of the converter output current after limiting to obtain the optimal value of the phase angle of the converter output current after limiting; including: calculating the optimal value of the phase angle of the converter output current after limiting based on the maximum value of the limit cut-off time corresponding to the phase angle of the converter output current.
[0053] Specifically, the optimal value of the phase angle of the converter output current after limiting is θ opt as follows:
[0054]
[0055] Through the above calculation, the optimal value of the phase angle of the converter output current after limiting can be obtained, so that the converter can obtain the maximum limit cut-off time under this value.
[0056] See Figure 2 As shown, Figure 2 A comparison chart of simulation verification provided for an embodiment of the present application. This embodiment uses a DC power supply to connect a test system with a weak power grid with a short-circuit ratio of 2 through a converter for simulation verification. The converter limiting current phase angle is selected from outside the value range, within the value range and the optimal value determined by the present invention. The active power reference value output by the converter is initially set to 3.5MW (rated capacity is 5MW). At time t=10.0s, the grid voltage drops from 1pu to 0.6pu, and the grid voltage recovers at t=13.4s. Figure 2 (a) is the simulation waveform of the converter limiting current phase angle outside the value range (θ = 0rad), Figure 2 (b) is the simulation waveform of the converter limiting current phase angle within the value range (θ = 0.55rad), Figure 2 (c) is the simulation waveform of the converter limiting current phase angle at the optimal value (θ = 1.30rad). Figure 2 It can be seen from the figure that when the converter limiting phase angle is outside the value range, the converter is still in the limiting control mode after the fault is removed; when the converter limiting phase angle is within the value range, the converter can exit the limiting control after the fault is removed and return to normal operation; when the converter limiting phase angle is at the optimal value, the converter will automatically exit the limiting control after the fault is removed and will not become unstable during the transient process.
[0057] It can be seen that compared with the prior art, the present application has the following advantages and effects: (1) The present application determines the value range of the converter current phase angle after limiting. It can ensure that when the converter current phase angle after limiting is within the value range, the converter can autonomously exit the current limiting control and restore normal operation after the fault is removed under various working conditions. (2) The present application determines the optimal value of the converter current phase angle after limiting. It can ensure that under the optimal value condition of the converter current phase angle after limiting, the converter obtains the maximum limit removal power angle and limit removal time.
[0058] See Figure 3 As shown, Figure 3 A structural diagram of a computer device provided in an embodiment of the present application. The computer device provided in an embodiment of the present application is used to implement a method for determining the value of the limiting current phase angle of a voltage source converter disclosed above. The computer device 300 may include one or more central processing units (CPUs) 322 (for example, one or more processors) and a memory 332, and one or more storage media 330 (for example, one or more mass storage devices) for storing application programs 342 or data 344. Among them, the memory 332 and the storage medium 330 may be temporary storage or permanent storage. The program stored in the storage medium 330 may include one or more modules (not shown in the figure), and each module may include a series of instruction operations in the computer device. Furthermore, the central processing unit 322 may be configured to communicate with the storage medium 330 to execute a series of instruction operations in the storage medium 330 on the computer device 300.
[0059] The computer device 300 may also include one or more power supplies 326, one or more wired or wireless network interfaces 350, one or more input and output interfaces 358, and / or one or more operating systems 341, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.
[0060] In the embodiment of the present application, the central processing unit 322 can be used to execute Figure 1 The method for determining the value of the limiting current phase angle of the voltage source converter in the corresponding embodiment.
[0061] An embodiment of the present application provides a computer storage medium including computer instructions. When the computer instructions are executed on a computer device, the computer device executes the method for determining the phase angle of the voltage source converter limiting current in any possible embodiment described above.
[0062] An embodiment of the present application provides a computer program product. When the computer program product is run on a computer device, the computer device is enabled to execute the method for determining the phase angle of the voltage source converter limiting current in any of the possible embodiments described above.
[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for determining the phase angle of the limiting current of a voltage source converter, characterized in that: include: S1. Obtain a reference value of the active power of the converter, obtain the effective value of the voltage at the converter connection point and the grid voltage, obtain the maximum allowable value of the converter output current, and obtain the equivalent reactance between the converter and the grid connection line; S2. Calculate the maximum allowable value of the output active power of the converter under normal operating state and limited operating state; S3, calculating the minimum value and the maximum value of the phase angle of the converter output current after limiting, and obtaining the value range of the phase angle of the converter output current after limiting; S4, calculating the power angle of the converter at a stable operating point and the power angle of the converter at an unstable operating point after limiting; S5, calculating the limit cut-off angle corresponding to the phase angle of the converter output current after limiting according to the equal area rule; S6. Calculate the limit cut-off time of the output current of the converter after limiting according to the limit cut-off angle of the output current phase angle of the converter after limiting; S7. Compare the limit cut-off time corresponding to the phase angle of the converter output current after limiting, and obtain the optimal value of the phase angle of the converter output current after limiting.
2. A method for determining the limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S2. Calculate the maximum allowable value of the output active power of the converter under normal operating state and limited operating state; including: Calculate the maximum allowable value of the converter's output active power under normal operating conditions based on the grid voltage, the effective value of the converter's grid connection point voltage, and the equivalent reactance between the converter and the grid connection line; According to the maximum allowable value of the converter output current and the effective value of the converter grid connection point voltage, the maximum allowable value of the output active power under the limited operation state is calculated.
3. The method for determining the limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S3, calculating the minimum value and the maximum value of the phase angle of the converter output current after limiting, and obtaining the value range of the phase angle of the converter output current after limiting; including: According to the reference value of the converter active power, the maximum allowable value of the output active power under the limited operation state, the effective value of the grid voltage and the converter grid connection point voltage, the maximum allowable value of the converter output current, and the equivalent reactance between the converter and the grid connection line, the minimum and maximum values of the converter output current phase angle after limiting are calculated.
4. The method for determining the limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S4. Calculate the power angle of the converter at the stable operating point and the power angle of the converter at the unstable operating point after limiting; including: Calculate the power angle of the converter stable operation point according to the active power reference value of the converter and the maximum allowable value of the output active power under normal operation of the converter; According to the active power reference value of the converter and the maximum allowable value of the output active power under the limited operation state, the power angle of the unstable operation point of the converter after limiting is calculated.
5. The method for determining the limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S5. Calculate the limit cut-off angle corresponding to the phase angle of the converter output current after limiting according to the equal area rule; including: According to the reference value of the converter active power, the power angle of the converter stable operating point, the power angle of the converter unstable operating point after limiting, the maximum allowable value of the output active power under the limited operating state and the output current phase angle of the converter, the limit cut-off angle corresponding to the output current phase angle of the converter after limiting is calculated.
6. The method for determining the limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S6, calculating the limit cut-off time of the converter output current after limiting according to the limit cut-off angle of the converter output current phase angle after limiting; including: The limit cutting time corresponding to the converter output current phase angle is calculated according to the inertia constant of the converter, the limit cutting angle corresponding to the converter output current phase angle after limiting, the power angle of the converter stable operation point, the grid reference angular velocity and the converter active power reference value.
7. A method for determining a limiting current phase angle of a voltage source converter according to claim 1, characterized in that: S7, comparing the limit removal time corresponding to the phase angle of the converter output current after limiting, and obtaining the optimal value of the phase angle of the converter output current after limiting; including: According to the maximum value of the limit switching time corresponding to the converter output current phase angle, the optimal value of the converter output current phase angle after limiting is calculated.
8. A computer device, characterized in that: The computer device comprises: a memory and a processor, wherein the processor is used to execute a computer program stored in the memory, so that the computer device executes a method for determining a value of a limiting current phase angle of a voltage source converter as described in any one of claims 1-7.
9. A computer storage medium, characterized in that It includes computer instructions. When the computer instructions are executed on a computer device, the computer device executes a method for determining a value of a limiting current phase angle of a voltage source converter as described in any one of claims 1 to 7.
10. A computer program product, characterized in that When the computer program product is run on a computer device, the computer device executes a method for determining a value of a limiting current phase angle of a voltage source converter as described in any one of claims 1 to 7.