Vpd-based node frequency offset measurement method, apparatus and device

Abstract

The application provides a VPD-based node frequency deviation measurement method, device and equipment, and relates to the technical field of power system control. The method comprises the following steps: acquiring the voltage of a measurement node in a power system and the admittance from a disturbance point to the measurement node; calculating the virtual power flowing through each node according to the voltage of the measurement node; and calculating the node frequency deviation between different nodes by using the Kirchhoff voltage law and the cosine theorem according to the virtual power and the admittance from the disturbance point to the measurement node. The node voltage and the admittance are directly acquired, so that the errors introduced by the hardware delay or the environmental interference of the traditional PLL or PMU are avoided. The virtual power is calculated, the dynamic characteristics of the power system are converted into quantifiable parameters. The mathematical relationship between the frequency deviation, the power and the admittance is established from the perspective of the circuit model by combining the Kirchhoff voltage law and the cosine theorem, so as to calculate the node frequency deviation, so that the measurement result is more in line with the actual physical behavior of the system, and the accuracy of the power system in measuring the node frequency deviation is improved.

Description

Technical Field

[0001] This invention relates to the field of power system control technology, and in particular to a method, apparatus and equipment for measuring node frequency deviation based on VPD. Background Technology

[0002] Against the backdrop of growing global demand for clean energy, the proportion of renewable energy sources such as wind and solar power in power systems is constantly increasing, posing challenges to the stable operation of power systems. Flexible DC transmission systems (Voltage Source Converter based High Voltage Direct Current Transmission, VSC-HVDC), as a key technology for solving renewable energy grid integration and improving grid stability, are being used more and more widely. However, due to the complex control involving multiple variables, the system is prone to instability after disturbances, affecting the measurement of node frequency deviation. With the increasing contradiction between the large-scale development of renewable energy and the reverse distribution of power load in my country, the demand for long-distance, large-capacity power transmission is growing, making high-voltage AC / DC hybrid transmission an important solution due to its technological advantages. However, when the DC system experiences a sudden power drop due to a fault, the power transfer to the AC side can cause frequency fluctuations in the AC system, leading to aggravated node frequency deviation and seriously threatening system stability. Existing research mainly focuses on the power angle stability, voltage stability, and control strategy optimization of AC / DC hybrid systems, while the accuracy of node frequency deviation measurement needs to be improved. Summary of the Invention

[0003] This invention provides a method, apparatus, and device for measuring node frequency deviation based on VPD, in order to solve the problem of improving the measurement accuracy of node frequency deviation.

[0004] In a first aspect, embodiments of the present invention provide a node frequency deviation measurement method based on VPD, comprising: Obtain the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node; The virtual power flowing through each node is calculated based on the voltage of the measured node; Based on the virtual power and the admittance from the disturbance point to the measurement node, the node frequency deviation between different nodes is calculated using Kirchhoff's voltage law and the cosine theorem.

[0005] In one possible implementation, the calculation of the node frequency deviation between different nodes using Kirchhoff's voltage law and the cosine theorem includes: Establish the nodal admittance matrix using Kirchhoff's voltage law; The expression for the virtual transmission power between nodes is determined using the law of cosines; Select any node as a reference node, and determine the potential expression of each node based on the node admittance matrix and the expression of the virtual transmission power; The node frequency deviation between different nodes is calculated based on the stated potential expression.

[0006] In one possible implementation, before calculating the node frequency deviation between different nodes using Kirchhoff's voltage law and the cosine theorem, the method further includes: Obtain node information of the power system; A simulation system model of the power system is built based on the node information.

[0007] In one possible implementation, the reference node is a converter node or an AC bus node in an AC / DC hybrid system.

[0008] In one possible implementation, the AC / DC hybrid system includes a flexible DC transmission system (VoltageSource Converter Based High Voltage Direct Current, VSC-HVDC) and an AC power grid.

[0009] In one possible implementation, the devices corresponding to the nodes in the simulation system model include photovoltaic power generation units, converters, DC buses, and AC loads.

[0010] In one possible implementation, the virtual power includes virtual active power and virtual reactive power; The calculation of the virtual power flowing through each node based on the voltage of the measurement node includes: The virtual active power is calculated based on the cosine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance. The virtual reactive power is calculated based on the sine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance.

[0011] In one possible implementation, the process of calculating the node frequency deviation between different nodes includes: The node frequency deviation is calculated based on the change in virtual active power before and after the disturbance, the differential operator, and the line reactance between nodes. The node frequency deviation is directly proportional to the change in virtual active power and inversely proportional to the product of the differential operator and the line reactance.

[0012] Secondly, embodiments of the present invention provide a node frequency deviation measurement device based on VPD, comprising: The acquisition module is used to acquire the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node; The virtual power calculation module is used to calculate the virtual power flowing through each node based on the voltage of the measurement node; The frequency deviation calculation module is used to calculate the node frequency deviation between different nodes based on the virtual power and the admittance from the disturbance point to the measurement node, using Kirchhoff's voltage law and the cosine theorem.

[0013] Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation thereof.

[0014] In this embodiment of the invention, firstly, node voltage and admittance are directly obtained, avoiding errors introduced by hardware delays or environmental interference in traditional PLLs or PMUs. Secondly, by calculating virtual power, the dynamic characteristics of the power system are transformed into quantifiable parameters. Finally, combining Kirchhoff's voltage law and cosine theorem, a mathematical relationship between frequency deviation and power and admittance is established from the perspective of circuit modeling to calculate node frequency deviation, making the measurement results more consistent with the actual physical behavior of the system and improving the accuracy of node frequency deviation measurement in the power system. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the implementation of a node frequency deviation measurement method based on VPD according to an embodiment of the present invention. Figure 2 This is a simulation structure diagram of an AC / DC hybrid system provided in an embodiment of the present invention; Figure 3 This is a comparison chart of node frequency deviations under frequency step conditions obtained by a node frequency deviation measurement method based on VPD provided in an embodiment of the present invention. Figure 4 This is a comparison chart of node frequency deviation under load conditions obtained by a node frequency deviation measurement method based on VPD provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of the node frequency deviation measurement device based on VPD provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0016] Existing research focuses on the power angle stability, voltage stability, and control strategy optimization of AC / DC hybrid systems. On the one hand, the difference in frequency dynamic response between parallel and non-parallel operation modes has not been fully quantified; on the other hand, the impact mechanism of line parameter changes on node frequency deviation in long-distance power transmission lacks systematic analysis.

[0017] Currently, phase-locked loops (PLLs) and phase measurement units (PMUs) are commonly used to measure node frequency deviation. However, these methods introduce measurement errors when measuring node frequency deviation in AC / DC hybrid systems, making it difficult to accurately analyze the spatiotemporal distribution characteristics of the system's frequency. Furthermore, in actual operation, PLLs are limited by their own hardware performance and complex electromagnetic interference, making it difficult for their tracking characteristics to reach an ideal state. This introduces a significant delay and attenuation effect into the converter's frequency response.

[0018] With the rapid increase in the proportion of new energy sources and power electronic equipment in power systems, the dynamic frequency characteristics of the systems have changed significantly, and their spatiotemporal distribution characteristics have a significant impact on the safe and stable operation of the systems. Traditional research is mostly based on the assumption that the frequencies of all nodes are consistent, ignoring the differences in frequency distribution in time and space. However, the large-scale grid connection of new energy units reduces the system inertia, making the spatiotemporal distribution characteristics of the frequency response increasingly significant, which poses new challenges to the frequency stability of the system. Existing research mainly focuses on traditional power systems, and there are still shortcomings in the study of the spatiotemporal frequency distribution characteristics of AC / DC hybrid systems.

[0019] Based on the aforementioned background and the shortcomings of existing research, this invention proposes a novel node frequency deviation measurement method based on VPD (Virtual Voltage Detection), aiming to overcome the limitations of traditional measurement methods and accurately obtain node frequency deviation information in power systems. This method uses VPD to calculate virtual power using virtual impedance and combines AC line parameters and measurement device data to calculate the "potential" between nodes, thereby deriving the node frequency deviation. This provides a new method for analyzing the spatiotemporal frequency distribution characteristics of AC / DC hybrid systems, significantly improving the accuracy of node frequency deviation measurement in power systems. The node frequency deviation obtained through VPD measurement can serve as a strong basis for analyzing the spatiotemporal frequency distribution characteristics of AC / DC hybrid systems.

[0020] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Figure 1 This is a flowchart illustrating the implementation of the node frequency deviation measurement method based on VPD provided in this embodiment of the invention. Figure 1 As shown, it includes the following steps: S101, obtain the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node.

[0022] The execution subject in various embodiments of the present invention can be a server, processor, microprocessor, or other device with data processing capabilities. In actual implementation, the specific implementation method of the execution subject can be selected according to actual needs. This embodiment does not impose any particular restrictions on this, as long as it is a device with data processing capabilities.

[0023] S102 calculates the virtual power flowing through each node based on the voltage of the measured node.

[0024] S103 calculates the node frequency deviation between different nodes using Kirchhoff's voltage law and cosine theorem, based on the virtual power and the admittance from the disturbance point to the measurement node.

[0025] The node frequency deviation between different nodes refers to the frequency difference between different nodes after a disturbance occurs in the power system, and its formula is as follows:

[0026] In the formula, Let be the potential difference between any two nodes; For nodes The potential difference between the reference node 4 and the reference node 4; For nodes The potential difference between the reference node and the reference node (node ​​4 in the formula). In this embodiment, firstly, node voltage and admittance are directly obtained, avoiding errors introduced by hardware delays or environmental interference in traditional PLLs or PMUs. Secondly, by calculating virtual power, the dynamic characteristics of the power system are transformed into quantifiable parameters. Finally, combining Kirchhoff's voltage law and cosine theorem, a mathematical relationship between frequency deviation and power and admittance is established from the perspective of circuit modeling to calculate node frequency deviation. This makes the measurement results more closely match the actual physical behavior of the system and improves the accuracy of node frequency deviation measurement in the power system.

[0027] In one possible implementation, Kirchhoff's voltage law and cosine theorem are used to calculate the node frequency deviation between different nodes, including: Establish the nodal admittance matrix using Kirchhoff's voltage law; The expression for the virtual transmission power between nodes is determined using the law of cosines; Select any node as a reference node, and determine the potential expression of each node based on the expression of the node admittance matrix and the virtual transmission power. Calculate the node frequency deviation between different nodes based on the potential expression.

[0028] The nodal admittance matrix, taking a node in the circuit model as the reference node, is expressed as follows:

[0029] In the formula, The admittance of each section of the transmission line.

[0030] By selecting a reference node and applying Kirchhoff's voltage law, the potential expressions for each node in the system can be obtained:

[0031] in, This is the potential matrix for each node; This is the power matrix representing the virtual power flowing through each node; Let be the admittance matrix.

[0032] In this embodiment, establishing a node admittance matrix comprehensively reflects the system topology and line parameters, avoiding the accumulation of local errors. The virtual transmission power expression is determined using the cosine theorem, linearizing the nonlinear power relationship and simplifying computational complexity. After selecting a reference node, the frequency deviation is derived based on the potential expression, ensuring the calculation results have clear physical meaning and global consistency. The application of Kirchhoff's voltage law and the cosine theorem improves the systematic nature and model accuracy of the frequency deviation calculation, meeting the requirements for rapid response under dynamic disturbances.

[0033] In one possible implementation, before calculating the node frequency deviation between different nodes using Kirchhoff's voltage law and the cosine theorem, the following is also included: Obtain node information of the power system; A simulation system model of the power system is built based on the node information.

[0034] In this embodiment, the completeness of node information (such as device parameters and connection relationships) ensures a high degree of matching between the model and the actual system, avoiding deviations caused by simplification assumptions. The dynamic model building capability of the simulation model enables the method to adapt to AC / DC hybrid systems of different scales. By acquiring node information and building a simulation system model before calculation, the reliability and scalability of the measurement method are enhanced.

[0035] In one possible implementation, the reference node is the converter node or AC bus node in a hybrid AC / DC system.

[0036] In this embodiment, the converter node is the core control point of the AC / DC hybrid system, and its voltage and power characteristics directly affect frequency dynamics; the AC bus node is usually the system hub and can reflect the frequency trend of the entire network. Selecting the converter node or the AC bus node as the reference point reduces errors caused by improper selection of the reference point, thereby improving the accuracy of the power system's measurement of node frequency deviation.

[0037] In one possible implementation, the AC / DC hybrid system includes a VSC-HVDC and an AC power grid.

[0038] In this embodiment, the VSC-HVDC has a fast power regulation capability, but its low inertia characteristic easily causes frequency fluctuations, and traditional measurement methods are insufficient in such systems. By combining the virtual power calculation of VPD, the interactive dynamics between the VSC converter and the AC grid can be effectively captured, providing data support for frequency stability control under high proportion of new energy grid connection.

[0039] like Figure 2 The diagram shown is a simulation structure diagram of an AC / DC hybrid system provided in an embodiment of the present invention. Figure 1 The system consists of photovoltaic power generation, a transformer, and sending-end converters (VSC1 and VSC2) at the sending end; and receiving-end converters (VSC3 and VSC4) and the receiving-end system (AC grid and AC loads) at the receiving end. Photovoltaic power generation produces AC power via the PV-VSC, which is then stepped up by the transformer, rectified by the sending-end converters, fed into the DC bus, and finally distributed to the AC grid and AC loads via the two receiving-end converters.

[0040] In one possible implementation, the devices corresponding to the nodes in the simulation system model include photovoltaic power generation units, converters, DC buses, and AC loads.

[0041] In one possible implementation, virtual power includes virtual active power and virtual reactive power; The virtual power flowing through each node is calculated based on the voltage at the measured node, including: The virtual active power is calculated based on the cosine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance. The virtual reactive power is calculated based on the sine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance.

[0042] Optionally, the formula for calculating the virtual power flowing through each node based on the voltage of the measured node is as follows:

[0043] In the formula, This is virtual active power; Virtual reactive power; , The voltage at both ends of the line. For output impedance, Virtual impedance angle, virtual impedance ∠ ; This represents the phase angle difference between nodes i and j.

[0044] In this embodiment, based on the cosine or sine relationship between the phase angle difference and the virtual impedance angle, node voltage and impedance parameters are converted into power quantities, avoiding errors caused by neglecting phase details in traditional power calculations. Simultaneously, the dynamic updating capability of virtual power (such as capturing changes before and after disturbances) provides a data foundation for real-time monitoring of frequency deviation, particularly suitable for AC / DC hybrid systems with high dynamic response. By accurately calculating virtual active and reactive power, the accuracy of frequency deviation derivation is fundamentally improved.

[0045] In one possible implementation, the process of calculating the node frequency deviation between different nodes includes: The node frequency deviation is calculated based on the change in virtual active power before and after the disturbance, the differential operator, and the line reactance between nodes. Among them, the node frequency deviation is directly proportional to the change in virtual active power and inversely proportional to the product of the differential operator and the line reactance.

[0046] Optionally, the formula for calculating the small-signal node frequency deviation after linearization, based on the circuit model, is as follows:

[0047] In the formula, The frequency difference between different nodes i and j The virtual active power change flowing through nodes i and j before and after the disturbance is represented. It is a differential operator. Represents the line reactance between nodes i and j. This represents the phase angle between nodes i and j.

[0048] In this embodiment, establishing the proportional relationship between node frequency deviation and the product of power change, differential operator, and reactance simplifies the calculation process, reduces the need for iterative calculations, and is suitable for online monitoring scenarios. Simultaneously, this relationship reveals the sensitivity of frequency deviation to system parameters (such as reactance). By clarifying the mathematical relationship between frequency deviation and virtual active power change, differential operator, and line reactance, the real-time performance and dynamic performance of the calculation are optimized, improving the accuracy of node frequency deviation measurement in the power system.

[0049] To verify the effectiveness of the VPD-based node frequency deviation measurement method provided in this embodiment of the invention, the following was selected: Figure 2 The AC / DC hybrid system shown was used for verification. To verify the effectiveness of the node frequency deviation obtained by VPD in this system, the actual node frequency deviation between two converters in each group was compared with the node frequency deviation obtained by VPD.

[0050] When a disturbance occurs in the system, the node frequency deviation obtained from the VPD (Variable Frequency Drive) basically matches the actual node frequency deviation between converters. However, at the instant the disturbance occurs, the power jump causes inaccuracies in the measurement of the node frequency deviation. The results are as follows... Figure 3 , 4 As shown.

[0051] To further verify the effectiveness of the node frequency deviation obtained by VPD, experimental tests were conducted in an AC / DC interconnected system, focusing on verifying the node frequency deviation between the sending and receiving ends under different disturbance schemes.

[0052] Two schemes were compared: Scheme A adopted frequency step disturbance, and Scheme B adopted load switching disturbance. The VSC at the sending and receiving ends of the system adopted droop control, with an inertia coefficient of 0.05 and a damping coefficient of 3 / 2.

[0053] Option A involves applying step disturbances of varying magnitudes to the system's transmitting frequency at different time points. The frequency step disturbance settings are shown in Table 1. Table 1 Frequency Step Disturbance Settings

[0054] Option B sets the load switching condition at the receiving end of the system, with 1800W load being put into operation at 3.3 seconds and the load being taken out of the system at 29.6 seconds.

[0055] The experimental waveforms and calculation results of the node frequency deviation for the two schemes are depicted.

[0056] In Scheme A, regardless of the magnitude of the frequency step disturbance applied at the system's sending end, oscillations will occur upon the occurrence of the step disturbance; however, the magnitude of the frequency step disturbance has no significant impact on the amplitude of the node frequency deviation (see Table 2). After one disturbance occurs, the oscillations gradually decrease until the next oscillation occurs. Furthermore, under this experimental condition, the node frequency deviation obtained by VPD measurement can accurately reflect the true node frequency deviation of the system.

[0057] Table 2. Node frequency deviation amplitude under frequency step

[0058] In Scheme B, unlike under frequency step disturbance, the node frequency deviation between the sending and receiving ends of the system not only oscillates after the load is applied, but also changes in the node frequency deviation in steady state. Compared to frequency step disturbance, the oscillations generated during load switching are more severe, as shown in Table 3. At the initial moment of the disturbance, the node frequency deviation obtained by VPD will show large oscillations, but it can quickly become consistent with the actual node frequency deviation.

[0059] Table 3 Steady-state values ​​of node frequency deviation

[0060] Under both disturbances, the node frequency deviations obtained by VPD are basically consistent with the actual node frequency deviations. Therefore, using VPD to obtain node frequency deviations can effectively verify the spatiotemporal frequency distribution characteristics of the system after disturbances.

[0061] This invention provides a node frequency deviation measurement method based on VPD. It obtains the voltage of the measurement node and the admittance from the disturbance point to the measurement node based on the circuit model; calculates the virtual power flowing through the node based on the node voltage, and obtains the node frequency deviation between different nodes by combining the admittance from the disturbance point to the node; based on the constructed simulation system model and experimental system, it uses Kirchhoff's voltage law and cosine theorem to obtain a calculation formula that can obtain the frequency deviation between different nodes of the system.

[0062] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0063] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0064] Figure 5 A schematic diagram of the node frequency deviation measurement device based on VPD provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 5 As shown, the VPD-based node frequency deviation measurement device 5 includes: The acquisition module 501 is used to acquire the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node; The virtual power calculation module 502 is used to calculate the virtual power flowing through each node based on the voltage of the measurement node. The frequency deviation calculation module 503 is used to calculate the node frequency deviation between different nodes based on the virtual power and the admittance from the disturbance point to the measurement node, using Kirchhoff's voltage law and the cosine theorem.

[0065] In one possible implementation, the frequency deviation calculation module 503 is specifically used for: Establish the nodal admittance matrix using Kirchhoff's voltage law; The expression for the virtual transmission power between nodes is determined using the law of cosines; Select any node as a reference node, and determine the potential expression of each node based on the node admittance matrix and the expression of the virtual transmission power; The node frequency deviation between different nodes is calculated based on the stated potential expression.

[0066] In one possible implementation, the acquisition module 501 is also used for: Obtain node information of the power system; A simulation system model of the power system is built based on the node information.

[0067] In one possible implementation, the reference node is a converter node or an AC bus node in an AC / DC hybrid system.

[0068] In one possible implementation, the AC / DC hybrid system includes a flexible DC transmission system (VoltageSource Converter Based High Voltage Direct Current, VSC-HVDC) and an AC power grid.

[0069] In one possible implementation, the devices corresponding to the nodes in the simulation system model include photovoltaic power generation units, converters, DC buses, and AC loads.

[0070] In one possible implementation, the virtual power includes virtual active power and virtual reactive power; Virtual power calculation module 502 is specifically used for: The virtual active power is calculated based on the cosine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance. The virtual reactive power is calculated based on the sine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance.

[0071] In one possible implementation, the frequency deviation calculation module 503 is specifically used for: The node frequency deviation is calculated based on the change in virtual active power before and after the disturbance, the differential operator, and the line reactance between nodes. The node frequency deviation is directly proportional to the change in virtual active power and inversely proportional to the product of the differential operator and the line reactance.

[0072] In this embodiment, firstly, node voltage and admittance are directly obtained, avoiding errors introduced by hardware delays or environmental interference in traditional PLLs or PMUs. Secondly, by calculating virtual power, the dynamic characteristics of the power system are transformed into quantifiable parameters. Finally, combining Kirchhoff's voltage law and cosine theorem, a mathematical relationship between frequency deviation and power and admittance is established from the perspective of circuit modeling to calculate node frequency deviation. This makes the measurement results more closely match the actual physical behavior of the system and improves the accuracy of node frequency deviation measurement in the power system.

[0073] Figure 6 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. For example... Figure 6 As shown, the electronic device 6 of this embodiment includes a processor 60 and a memory 61. The memory 61 stores a computer program 62. When the processor 60 executes the computer program 62, it implements the steps in the various method embodiments described above. Alternatively, when the processor 60 executes the computer program 62, it implements the functions of each module / unit in the various device embodiments described above.

[0074] For example, computer program 62 may be divided into one or more modules / units, which are stored in memory 61 and executed by processor 60 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 62 in electronic device 6.

[0075] Electronic device 6 may include, but is not limited to, processor 60 and memory 61. Those skilled in the art will understand that... Figure 6 This is merely an example of electronic device 6 and does not constitute a limitation on electronic device 6. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device 6 may also include input / output devices, network access devices, buses, etc.

[0076] For the sake of simplicity and clarity, only the above-described functional modules / units are used as examples. In practical applications, the functions described above can be assigned to different functional modules / units as needed. These modules / units can be implemented in hardware, software, or a combination of both.

[0077] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0078] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A node frequency deviation measurement method based on VPD, characterized in that, Includes the following steps: Obtain the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node; The virtual power flowing through each node is calculated based on the voltage of the measured node; Based on the virtual power and the admittance from the disturbance point to the measurement node, the node frequency deviation between different nodes is calculated using Kirchhoff's voltage law and the cosine theorem.

2. The node frequency deviation measurement method based on VPD according to claim 1, characterized in that, The calculation of node frequency deviations between different nodes using Kirchhoff's voltage law and cosine theorem includes: Establish the nodal admittance matrix using Kirchhoff's voltage law; The expression for the virtual transmission power between nodes is determined using the law of cosines; Select any node as a reference node, and determine the potential expression of each node based on the node admittance matrix and the expression of the virtual transmission power; The node frequency deviation between different nodes is calculated based on the stated potential expression.

3. The node frequency deviation measurement method based on VPD according to claim 2, characterized in that, Before calculating the node frequency deviation between different nodes using Kirchhoff's voltage law and the cosine theorem, the method further includes: Obtain node information of the power system; A simulation system model of the power system is built based on the node information.

4. The node frequency deviation measurement method based on VPD according to claim 3, characterized in that, The reference node is the converter node or AC bus node in the AC / DC hybrid system.

5. The node frequency deviation measurement method based on VPD according to claim 4, characterized in that, The AC / DC hybrid system includes a flexible DC transmission system and an AC power grid.

6. The node frequency deviation measurement method based on VPD according to claim 5, characterized in that, The devices corresponding to the nodes in the simulation system model include photovoltaic power generation units, converters, DC buses, and AC loads.

7. The node frequency deviation measurement method based on VPD according to claim 1, characterized in that, The virtual power includes virtual active power and virtual reactive power; The calculation of the virtual power flowing through each node based on the voltage of the measurement node includes: The virtual active power is calculated based on the cosine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance. The virtual reactive power is calculated based on the sine of the sum of the phase angle difference and the virtual impedance angle, the product of the node voltages, and the output impedance.

8. The node frequency deviation measurement method based on VPD according to claim 1, characterized in that, The process of calculating the node frequency deviation between different nodes includes: The node frequency deviation is calculated based on the change in virtual active power before and after the disturbance, the differential operator, and the line reactance between nodes. The node frequency deviation is directly proportional to the change in virtual active power and inversely proportional to the product of the differential operator and the line reactance.

9. A node frequency deviation measurement device based on VPD, characterized in that, include: The acquisition module is used to acquire the voltage of the measurement node in the power system and the admittance from the disturbance point to the measurement node; The virtual power calculation module is used to calculate the virtual power flowing through each node based on the voltage of the measurement node; The frequency deviation calculation module is used to calculate the node frequency deviation between different nodes based on the virtual power and the admittance from the disturbance point to the measurement node, using Kirchhoff's voltage law and the cosine theorem.

10. An electronic device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in any one of claims 1 to 8.

Images