A method for accurate measurement of inter-node frequency offset based on power measurement

Abstract

This invention discloses a method for accurately measuring inter-node frequency deviation based on power measurement, comprising the following steps: after a disturbance occurs in the power system, acquiring parameter data of the line transmission nodes, verifying the validity of the data, and eliminating outliers; using the arcsine function direct calculation method to solve for the inter-node phase difference, thus avoiding the problem of large inter-node phase difference errors caused by linearization; calculating the line transmission power based on the traditional power measurement method; and calculating the inter-node frequency deviation values ​​between different nodes. This invention introduces a virtual coordinate transformation of the active and reactive power of the line to eliminate the influence of the line resistance component on the measurement accuracy of inter-node frequency deviation in low-voltage power grids; the introduction of the arcsine function direct calculation method eliminates the problem of increased inter-node frequency deviation measurement errors caused by large inter-node phase differences due to linearization; for directly interconnected or indirectly interconnected nodes, this influence can be eliminated by introducing virtual coordinate transformation and virtual impedance, thereby improving measurement accuracy.

Description

Technical Field

[0001] This invention belongs to the field of frequency stability assessment technology for new energy power systems, and particularly relates to a method for accurately measuring inter-node frequency deviation based on power measurement. 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 continuously increasing, posing challenges to the stable operation of power systems. The equivalent inertia time constant of the system is declining, and the degree of frequency variation under disturbance events is increasing, leading to frequent power system faults. This is closely related to the system's inertia support and frequency regulation capabilities during fault occurrence. Flexible direct current transmission systems (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 multivariate control involved, the system is prone to instability after being disturbed, affecting the measurement of inter-node frequency deviations. The measurement of inter-node frequency deviations is crucial for studying the spatiotemporal distribution characteristics of power system frequencies, thus impacting power system stability.

[0003] 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, high-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 increased frequency deviations between nodes 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, but the accurate measurement and evaluation of frequency deviations between nodes remains insufficient. Since the node frequency response is closely related to the dynamics and distribution of all equipment in the system, as well as network topology, its analysis is more complex than that of global frequency.

[0004] Existing technologies generally employ P / wThe "admittance" circuit modeling method obtains the active power-frequency response small-signal circuit model of the simulation system, acquires the power flowing through the nodes and the admittance from the disturbance point to the node, determines the frequency of the node based on the power flowing through the node and the admittance from the disturbance point to the node, obtains the frequencies of different nodes based on the power measurement method, and calculates the frequency deviation between different nodes by subtracting them pairwise. However, the power measurement method, when measuring the frequency deviation between nodes in the system, mainly relies on the system's impedance and power. In low-voltage systems, the resistive component R and the inductive component X of the impedance in the line are not significantly different, which affects the acquired power. After the system is disturbed, there is a phase difference between different nodes in the actual system, and the magnitude of the phase difference also affects the power calculation, leading to errors in calculating the frequency deviation between two nodes. In addition, existing technologies generally use a linearized small-signal method to handle phase difference-related calculations. This method introduces significant linearization errors when the phase difference is large, further reducing the accuracy of the frequency deviation measurement between nodes.

[0005] While power measurement-based methods for calculating inter-node frequency deviation can capture the frequency differences between different nodes in a power system, their accuracy remains insufficient. The influence of line impedance and phase difference on measurement accuracy is significant. Therefore, to improve the accuracy of power measurement-based inter-node frequency deviation measurement methods, it is necessary to develop a more precise method that eliminates the influence of line impedance and phase difference. Summary of the Invention

[0006] The purpose of this invention is to provide a precise method for measuring inter-node frequency deviation based on power measurement, so as to solve the technical problem that the power measurement method in the prior art is not accurate enough due to the influence of line impedance and phase difference.

[0007] To address the aforementioned technical problems, this invention provides a method for accurately measuring inter-node frequency deviation based on power measurement, comprising the following steps: S1. After a disturbance occurs in the power system, acquire parameter data of the line transmission nodes, including node voltage and reactance components, verify the validity of the data, and remove outliers. S2. The phase difference between nodes is solved by the direct calculation method of the arcsine function; S3. Calculate the line transmission power based on the traditional power measurement method; S4. Calculate the frequency deviation between different nodes.

[0008] Preferably, in step S3, the formula for calculating line transmission power is: In the formula: U i U j δ represents the voltage at both ends of the line. ijX represents the phase difference of the voltages across the line. lineij This represents the reactance component of the line.

[0009] Preferably, step S2 specifically involves: based on the calculation formula for the line transmission power, adjusting the phase difference δ... ij The direct solution formula is as follows: The formula for directly calculating the phase difference using the arcsine function is: Considering the phase difference δ in the power system ij The actual range of values ​​for the arcsine function is such that the solution obtained by direct calculation is unique, and no additional quadrant determination is required.

[0010] Preferably, step S4 specifically comprises: The dynamic relationship between frequency and phase difference is as follows: By differentiating the formula for directly calculating the phase difference using the arcsine function, the precise formula for calculating the frequency deviation between nodes can be obtained: .

[0011] Preferably, in order to avoid the influence of the line resistance component in the low-voltage power grid on the accuracy of the frequency deviation between measurement nodes, in step S3, a virtual coordinate transformation of the active and reactive power of the line is introduced to calculate the first virtual power of the line.

[0012] Preferably, the virtual coordinate transformation and coefficient matrix formulas are as follows: In the formula: P ij 'and Q ij These are the first virtual active power and reactive power, respectively. α ij The impedance angle is the line impedance.

[0013] Preferably, the first virtual power includes active power and reactive power, and the formula for calculating the first virtual active power is: In the formula: U i U j The voltage at both ends of the line. δ ij Let Z be the phase difference between two nodes in the system, and Z be the line impedance. The calculation formula is: Z = R +j X。

[0014] Preferably, after introducing virtual coordinate transformation, the formula for directly calculating the phase difference using the arcsine function is: The precise formula for calculating the frequency deviation between nodes is: .

[0015] Preferably, the measurement nodes include nodes that are directly interconnected or indirectly interconnected. When the measurement nodes are not directly interconnected by power lines, it is impossible to accurately obtain the power difference through direct methods, nor is it possible to obtain the first virtual power through virtual coordinate transformation. In step S3, a virtual impedance is constructed between two nodes that are not directly interconnected. Without considering the actual line data, the second virtual power is calculated. Then, the virtual coordinate transformation of the active and reactive power of the line is introduced to eliminate the influence of the line resistance component on the measurement accuracy of the frequency deviation between nodes.

[0016] Preferably, the construction of the virtual impedance specifically involves: in U i with U j Introducing virtual impedance Z syn ∠α syn The second virtual active power P flows through the virtual impedance. ij '' and the second virtual reactive power Q ij The calculation formula is: In the formula: U i U j Let α be the voltage between two unconnected nodes in the circuit. syn Z is the virtual impedance angle. syn Z is the virtual impedance magnitude. Virtual impedance and the second virtual power are meaningless in the actual circuit, therefore Z is set to... syn =1, α syn =0.

[0017] Compared with the prior art, the beneficial effects of the present invention are: To improve the accuracy and applicability of frequency deviation measurement between nodes, the technical solution of this application does not require knowledge of the internal structure and control parameters of the unit. It can obtain the frequency deviation between nodes simply by measuring power fluctuations, thus avoiding the measurement delay of PLL, the transformer error of PMU and the interference of the field environment.

[0018] To address the issue of uneven distribution of inertia and frequency regulation resources in power systems with a high proportion of new energy sources, this paper aims to solve the problem of resistance components affecting the power measurement method when measuring frequency deviation between low-voltage grid nodes. By analyzing the interference mechanism of line resistance components on the power measurement method, this influence can be eliminated by introducing virtual coordinate transformation and virtual impedance for nodes that are directly or indirectly interconnected, thereby improving measurement accuracy. Furthermore, the spatiotemporal distribution characteristics of frequency between different regions in the system are analyzed.

[0019] Since power measurement methods are affected by line resistance components in actual power grid systems, a virtual coordinate transformation method is proposed to calculate power. The virtual powers Pi' and Qi' obtained through virtual coordinate transformation are related to the phase angle and voltage, respectively, and there is no coupling between them. For nodes (buses) without direct power line interconnection, the introduction of a second virtual power can significantly improve the accuracy of power measurement methods in measuring frequency deviations between non-directly connected nodes.

[0020] To address the error problem caused by the linearized small-signal method in existing technologies for handling phase differences, this application proposes a technical solution that directly calculates the phase difference using the arcsine function. This method replaces the traditional linearized small-signal method by directly calculating the phase difference, avoiding the error introduced by the linearized approximation when the phase difference is large. It can still maintain high-precision measurement even in scenarios with large disturbance intensity and significant phase difference fluctuations, eliminating the influence of the phase difference on frequency measurement and further broadening the applicability of the method.

[0021] Dual optimization enables accurate measurement across all scenarios. By combining virtual coordinate transformation with direct calculation of arcsine function, a precise measurement system with "dual interference elimination" is constructed. This eliminates dual interference caused by resistance components and phase differences, enabling accurate measurement of inter-node frequency deviations in scenarios ranging from high voltage to low voltage and from slight disturbances to severe disturbances. This significantly improves the accuracy and robustness of inter-node frequency deviation measurement, providing reliable data support for the analysis of the spatiotemporal distribution characteristics of power system frequencies. Attached Figure Description

[0022] Figure 1 A method flowchart of one embodiment provided in this application; Figure 2 A schematic diagram of a 3-machine 9-node computing system structure is provided in this application. Figure 3 One embodiment provided in this application is based on P / w A schematic diagram of the circuit model of "admittance"; Figure 4 A virtual impedance model diagram of one embodiment provided in this application; Figure 5A flowchart of a frequency spatiotemporal distribution difference assessment method provided in this application. Detailed Implementation

[0023] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, top, bottom, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of the components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or IoT terminal that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or IoT terminals.

[0024] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, this invention provides a method for accurately measuring inter-node frequency deviation based on power measurement, comprising the following steps: S1. After a disturbance occurs in the power system, acquire parameter data of the line transmission nodes, including node voltage and reactance components, verify the validity of the data, and remove outliers. S2. The phase difference between nodes is solved by direct calculation using the arcsine function to avoid the problem of large phase difference error between nodes caused by linearization. S3. Calculate the line transmission power based on the traditional power measurement method; S4. Calculate the frequency deviation between different nodes.

[0027] The comparison scheme uses the traditional power measurement method and obtains the circuit model of the example system through the P / w “admittance” circuit modeling method. Then, the transfer function of the frequency deviation between nodes is solved, and the frequency deviation response between nodes is theoretically analyzed in the frequency domain and time domain.

[0028] like Figure 2-3 As shown, with Figure 2 Taking the example system as an example, according to the P / w "admittance" method, the following can be obtained: Figure 3 The active power-frequency response small-signal circuit model is presented. In this model, the current flowing through the branch is ΔP, where ΔP represents the power change before and after the disturbance. The "admittance" of the branch can be based on... Figure 2 The actual impedance parameters between adjacent nodes are calculated, while the voltage drop across the "admittance" can be compared to Δw.

[0029] Figure 3 In the circuit model, under load disturbance excitation ΔP c If the flow ΔP flowing through each admittance Y is measured... ij (i≠j), then according to Ohm's law, the voltage drop Δw of each "admittance" can be calculated. ij The corresponding relationship is: ΔP ij correspond Figure 2 The change in active power flowing through nodes i and j before and after the disturbance, Δw, is the change in active power. Figure 2 The frequency difference between nodes i and j (inter-node frequency deviation). Based on this, after a disturbance occurs, the frequency difference between adjacent nodes in the system can be calculated according to the "admittance" and the measured power, thus reflecting the spatiotemporal frequency distribution characteristics of the system.

[0030] Figure 3 Middle Y lineij Y represents the "admittance" of each transmission line segment. Ti This refers to the "admittance" of a transformer. The "admittance" of a transmission line is Y. lineij (s)=K lineij / s, the transformer admittance is Y Ti (s)=K Ti / s, the output admittance of the power supply is Y bi (s)=K bi / s. Each "admittance" is determined by the ratio of ΔP / Δw. Taking the line "admittance" as an example, the specific derivation process is as follows: The formula for calculating line transmission power is: (4) In the formula: U i U j δ represents the voltage at both ends of the line. ij X represents the phase difference of the voltages across the line. lineijThe resistance is the reactance component of the line. Since the simulation system is at a high voltage level, the resistance can be ignored.

[0031] Linearizing equation (4) yields the small-signal formula: (5) Among them, it can be set that: (6) Therefore, equation (5) can be written as: (7) According to equation (7), the measured power is first subjected to discrete differential operation, and then divided by the coefficient K. lineij That is, the frequency deviation Δw between adjacent nodes i and j is obtained. ij .

[0032] In one specific embodiment provided in this application, after the system is disturbed, the phase difference between nodes... δ ij This may exceed the applicable range of small-signal linearization. In such cases, using linearization methods will introduce non-negligible errors, thus affecting the accuracy of frequency deviation calculation between nodes. To eliminate the influence of phase difference on frequency measurement, this invention proposes a method for directly calculating the arcsine function, replacing the traditional linearized small-signal method and avoiding the errors caused by linearization.

[0033] Based on the calculation formula (Equation 4) for the line transmission power, the phase difference δ ij The direct solution formula is as follows: (14) The formula for directly calculating the phase difference using the arcsine function is: (15) Considering the phase difference δ in the power system ij The actual range of values ​​(usually between ±90°) is such that the solution of the arcsine function is unique and no additional quadrant determination is required.

[0034] The dynamic relationship between frequency and phase difference is as follows: (16) By differentiating the phase difference formula (Equation 15) directly from the arcsine function, the precise formula for calculating the frequency deviation between nodes can be obtained: (17) The aforementioned direct calculation method of the arcsine function directly solves for the phase difference based on power measurements and system parameters, without the need for linearization approximation. It can maintain calculation accuracy even in scenarios with large phase differences and effectively eliminate the influence of phase differences on frequency measurements.

[0035] In one specific embodiment provided in this application, in a low-voltage power grid, the system lines exhibit resistivity and inductance, with the resistance and inductance being roughly equal. The resistance component can affect the calculation of transmitted power. To improve the measurement accuracy of power measurement methods in low-voltage power grids, a virtual coordinate transformation is proposed to eliminate the influence of the resistance component on the calculation accuracy in low-voltage power grids.

[0036] When only the line impedance is considered, the active power and reactive power transmitted on the line are respectively: (8) (9) Where: δ ij The phase difference between two nodes in the system is given by Z = R + jX, and α is given by α. ij Let be the impedance angle of the line impedance. At this point, equations (8) and (9) show that adjusting the voltage amplitude will simultaneously cause P... ij and Q ij Changes in phase angle will also cause P to change. ij and Q ij The changes in power are coupled, and the calculation accuracy is affected by many factors.

[0037] To avoid the influence of line resistance components on the accuracy of frequency deviation between measurement nodes in low-voltage power grids, in step S3, a virtual coordinate transformation is introduced to calculate the first virtual power of the line, which includes active power and reactive power.

[0038] The formulas for virtual coordinate transformation and coefficient matrix are as follows: (10) (11) In the formula: P ij 'and Q ij 'These are the first virtual active power and reactive power, respectively, α ij The impedance angle is the line impedance.

[0039] Substituting equation (10) into equations (8) and (9), we can obtain the first virtual active power and the first virtual reactive power, calculated as follows: (12) (13) In the formula: U i U j δ represents the voltage at both ends of the line. ij Z represents the phase difference between two nodes in the system, and Z represents the line impedance. The calculation formula is Z = R + jX. 。

[0040] Equations (12) and (13) show that the first virtual power P obtained through virtual coordinate transformation ij '、Q ij 'Respectively with phase angle δ ij Voltage amplitude related, first virtual power P ij '、Q ij The adjustment of ' is not coupled. Therefore, it is less affected by system parameters in calculation, thus improving measurement accuracy.

[0041] In low-voltage power grid scenarios, the first virtual power P after virtual coordinate transformation is used. ij Substituting equation (12) into equation (15), we can obtain the formula for directly calculating the phase difference using the arcsine function: (18) The precise formula for calculating the frequency deviation between nodes is as follows: (19).

[0042] In one specific embodiment provided in this application, the measurement nodes include directly interconnected or indirectly interconnected nodes. The virtual power calculated through virtual coordinate transformation is not limited to two directly interconnected nodes; indirectly connected nodes can also be measured using the virtual coordinate transformation method. When there is no direct power line interconnection between the observed nodes, the power difference between them cannot be accurately obtained through direct methods, nor can the first virtual power be obtained through virtual coordinate transformation. In step S3, a virtual impedance is constructed between two nodes that are not directly interconnected, and a second virtual power is calculated. The frequency difference between the two nodes is obtained through the second virtual power. Since actual line data is not considered, the influence of line parameters on the calculation can be ignored.

[0043] Specifically, for nodes (busbars) directly interconnected by power lines, the data to be collected is the active and reactive power data transmitted by the lines under disturbance conditions (sampling frequency > 2000Hz required). For nodes (busbars) not directly interconnected by power lines, the data to be collected is the instantaneous three-phase voltage data of each node under disturbance conditions (sampling frequency > 2000Hz required).

[0044] like Figure 4 The model shown constructs the virtual impedance as follows: in U i with U j Introducing virtual impedance Z syn ∠α syn The second virtual active power P flows through the virtual impedance. ij '' and the second virtual reactive power Q ij The calculation formula is: (20) In the formula: U i U j Let α be the voltage between two unconnected nodes in the circuit. syn Z is the virtual impedance angle. syn This represents the virtual impedance amplitude.

[0045] Generally, virtual impedance and the second virtual power are only used to determine the lead-lag relationship between them during the control process, and are meaningless in actual circuits. Therefore, Z is set. syn =1, α syn =0. When a disturbance occurs in the system, the virtual power before and after the disturbance is recorded to obtain the virtual power change ΔP. ij ''.

[0046] Then, a virtual coordinate transformation of the active and reactive power of the line is introduced to eliminate the influence of the line resistance component on the measurement accuracy of the frequency deviation between nodes; the direct calculation method of arcsine function is introduced to eliminate the problem of increased measurement error of frequency deviation between nodes when the phase difference between nodes is large due to linearization.

[0047] In one specific embodiment provided in this application, such as Figure 5 As shown, this application also provides a method for accurately assessing the frequency spatiotemporal distribution differences based on power measurements. After a disturbance occurs in the system, the inter-node frequency deviations between different nodes in the system are calculated by acquiring system parameters, and this is used to analyze the frequency spatiotemporal distribution characteristics of the system. Based on this, virtual coordinate transformation, arcsine wave, and virtual impedance methods are employed to improve the accuracy of the calculation method. The specific steps are as follows: Step 1, Data Acquisition: Obtain electrical quantity data of the power system under study during operation, such as tie line transmission power, observe the phase difference of voltage between nodes, line impedance between nodes, and impedance angle of line impedance.

[0048] Step 2, Preprocessing: Construct a virtual coordinate transformation coefficient matrix between different nodes using the obtained line impedance angles between different nodes in the system; based on the obtained line impedance angle α... ij Construct the virtual coordinate transformation coefficient matrix T between different nodes. ij (See Equation 11); For nodes that are not directly interconnected by power lines, a virtual impedance is introduced to verify the validity of the collected data, eliminate outliers, and ensure the accuracy of data such as power, voltage, and impedance.

[0049] Step 3, Calculation: After the disturbance, select the nodes to be observed. Using the obtained node voltage and impedance data, calculate the first set of inter-node frequency deviation data Δw based on the traditional power measurement method (Equation 7). ij -base; Substituting the collected power data into the virtual coordinate transformation formula (Equation 10), the first virtual power P is obtained. ij Then, based on the transformation of equation (7), the second set of inter-node frequency deviation data Δw is calculated. ij -res (eliminates the influence of resistive components); The second virtual power P is obtained based on equation (20). ij '', Perform calculations to eliminate the effects of phase difference: Based on the original power P ij The frequency deviation data Δw between the nodes in the third group was calculated using the direct calculation method of the arcsine function (Equation 17). ij -phase1 (eliminates phase difference linearization error); Based on the first virtual power P ij The fourth set of inter-node frequency deviation data Δw was calculated using the direct calculation method of the arcsine function (Equation 19). ij -phase2 (simultaneously eliminates resistance component and phase difference linearization error); Based on the second virtual power P ij The fifth set of inter-node frequency deviation data Δw was calculated using the traditional power measurement method (Equation 7). ij -phase3.

[0050] Step 4, Verification: The frequency deviation data between the nodes of the above sets are verified in the example system to verify the effect of virtual coordinate transformation on the elimination of resistance components and the effect of direct calculation of arcsine function on the elimination of phase difference linearization error.

[0051] Step 5, Evaluation: Select the set of frequency deviation data between nodes with the highest accuracy, and combine it with evaluation indicators to analyze the spatiotemporal distribution characteristics of frequency between different nodes in the system, so as to provide an accurate basis for power system stability analysis.

[0052] The evaluation indicators include: Steady-state frequency deviation between nodes: The frequency deviation between nodes after the system enters a stable operating state. This indicator is the key to evaluating the long-term frequency stability of the system and directly reflects the final state of active power balance. Maximum frequency deviation between nodes: refers to the absolute value of the peak frequency deviation between nodes during transient processes (such as load changes or unit tripping). This indicator is used to measure the system's ability to resist disturbances and is an important basis for formulating safe and stable control strategies such as low-frequency load shedding and high-frequency unit tripping. Inter-node frequency deviation compliance rate: refers to the percentage of time within the national standard limit during the statistical period, used to assess the operational reliability and power supply quality of the power system.

[0053] This invention addresses the problem of uneven distribution of inertia and frequency regulation resources in power systems with a high proportion of new energy sources. It solves the problem of the influence of resistance components on the power measurement method when measuring the frequency deviation between low-voltage power grid nodes. By analyzing the interference mechanism of line resistance components on the power measurement method, this influence can be eliminated by introducing virtual coordinate transformation and virtual impedance for nodes that are directly or indirectly interconnected, thereby improving the measurement accuracy. Furthermore, it analyzes the spatiotemporal distribution characteristics of frequency between different regions in the system.

[0054] Since power measurement methods are affected by line resistance components in actual power grid systems, a virtual coordinate transformation method is proposed to calculate power. The virtual powers Pi' and Qi' obtained through virtual coordinate transformation are related to the phase angle and voltage, respectively, and there is no coupling between them. For nodes (buses) without direct power line interconnection, the introduction of a second virtual power can significantly improve the accuracy of power measurement methods in measuring frequency deviations between non-directly connected nodes.

[0055] To address the error problem caused by the linearized small-signal method in existing technologies for handling phase differences, this application proposes a technical solution that directly calculates the phase difference using the arcsine function. This method replaces the traditional linearized small-signal method by directly calculating the phase difference, avoiding the error introduced by the linearized approximation when the phase difference is large. It can still maintain high-precision measurement even in scenarios with large disturbance intensity and significant phase difference fluctuations, eliminating the influence of the phase difference on frequency measurement and further broadening the applicability of the method.

[0056] Dual optimization enables accurate measurement across all scenarios. By combining virtual coordinate transformation with direct calculation of arcsine function, a precise measurement system with "dual interference elimination" is constructed. This eliminates dual interference caused by resistance components and phase differences, enabling accurate measurement of inter-node frequency deviations in scenarios ranging from high voltage to low voltage and from slight disturbances to severe disturbances. This significantly improves the accuracy and robustness of inter-node frequency deviation measurement, providing reliable data support for the analysis of the spatiotemporal distribution characteristics of power system frequencies.

[0057] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the specific details described above. The above description is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features of this application.

[0058] The above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Any modifications or equivalent substitutions made within the spirit and principles of this application shall be included within the protection scope of this application.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for accurately measuring inter-node frequency deviation based on power measurement, characterized in that, Including the following steps: S1. After a disturbance occurs in the power system, acquire parameter data of the line transmission nodes, including node voltage and reactance components, verify the validity of the data, and remove outliers. S2. The phase difference between nodes is solved by the direct calculation method of the arcsine function; S3. Calculate the line transmission power based on the traditional power measurement method; S4. Calculate the frequency deviation between different nodes.

2. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 1, characterized in that, In step S3, the formula for calculating line transmission power is: In the formula: U i U j δ represents the voltage at both ends of the line. ij X represents the phase difference of the voltages across the line. lineij This represents the reactance component of the line.

3. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 2, characterized in that, Step S2 specifically involves: based on the calculation formula for the line transmission power, calculating the phase difference δ... ij The direct solution formula is as follows: The formula for directly calculating the phase difference using the arcsine function is: Considering the phase difference δ in the power system ij The actual range of values ​​for the arcsine function is such that the solution obtained by direct calculation is unique, and no additional quadrant determination is required.

4. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 3, characterized in that, Step S4 specifically involves: The dynamic relationship between frequency and phase difference is as follows: By differentiating the formula for directly calculating the phase difference using the arcsine function, the precise formula for calculating the frequency deviation between nodes can be obtained: 。 5. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 1, characterized in that, To avoid the influence of line resistance components on the accuracy of frequency deviation between measurement nodes in low-voltage power grids, in step S3, a virtual coordinate transformation of the active and reactive power of the line is introduced to calculate the first virtual power of the line.

6. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 5, characterized in that, The formulas for the virtual coordinate transformation and coefficient matrix are as follows: In the formula: P ij 'and Q ij These are the first virtual active power and reactive power, respectively. α ij The impedance angle is the line impedance.

7. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 5, characterized in that, The first virtual power includes active power and reactive power, and the formula for calculating the first virtual active power is as follows: In the formula: U i U j The voltage at both ends of the line. δ ij Let Z be the phase difference between two nodes in the system, and Z be the line impedance. The calculation formula is: Z = R +j X。 8. The method for accurate measurement of inter-node frequency deviation based on power measurement according to claim 7, characterized in that, After introducing virtual coordinate transformation, the formula for directly calculating the phase difference using the arcsine function is: The precise formula for calculating the frequency deviation between nodes is: 。 9. A method for accurately measuring inter-node frequency deviation based on power measurement according to claim 5, characterized in that, The measurement nodes include nodes that are directly interconnected or indirectly interconnected. When the measurement nodes are not directly interconnected by power lines, the power difference cannot be accurately obtained by direct methods, nor can the first virtual power be obtained by virtual coordinate transformation. In step S3, a virtual impedance is constructed between two nodes that are not directly interconnected. Without considering the actual line data, the second virtual power is calculated. Then, the virtual coordinate transformation of the active and reactive power of the line is introduced to eliminate the influence of the line resistance component on the measurement accuracy of the frequency deviation between nodes.

10. A method for accurately measuring inter-node frequency deviation based on power measurement according to claim 9, characterized in that, The construction of the virtual impedance specifically involves: in U i with U j Introducing virtual impedance Z syn ∠α syn The second virtual active power P flows through the virtual impedance. ij '' and the second virtual reactive power Q ij The calculation formula is: In the formula: U i U j Let α be the voltage between two unconnected nodes in the circuit. syn Z is the virtual impedance angle. syn Z is the virtual impedance magnitude. Virtual impedance and the second virtual power are meaningless in the actual circuit, therefore Z is set to... syn =1, α syn =0.

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