CN-121995109-A - Method and device for measuring broadband impedance of power distribution network

Abstract

The invention relates to the technical field of electric power, in particular to a method and a device for measuring broadband impedance of a power distribution network, wherein the method comprises the steps of obtaining a non-injection type impedance measurement impedance value and an injection type impedance measurement impedance value of the power distribution network; and fusing the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value to obtain an impedance measurement final value. The method and the device remarkably improve the band integrity and the accuracy of impedance measurement, eliminate the inherent defects of a single method, provide reliable technical support for stable operation and resonance suppression of the power distribution network, and are suitable for the application scene of the modern power distribution network containing high-proportion distributed energy.

Inventors

• YANG LIU
• WANG TONGXUN
• ZHOU SHENGJUN
• SHEN BING
• ZHAO QIAN
• LI ZHAOLIANG
• LI FANGYI
• LIU HAIJUN
• ZHANG PENG
• MU XIAOBIN
• LI WEIGUO
• ZHAO GUOLIANG
• WANG ZHIKAI

Assignees

• 国家电网有限公司
• 中国电力科学研究院有限公司
• 国网上海市电力公司

Dates

Publication Date

20260508

Application Date

20251201

Claims (20)

1. 1. A method for measuring broadband impedance of a power distribution network, the method comprising: Acquiring a non-injection type impedance measurement impedance value and an injection type impedance measurement impedance value of the power distribution network; and fusing the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value to obtain an impedance measurement final value.
2. 2. The method of claim 1, wherein the non-injected impedance measurement impedance values are as follows: In the above-mentioned method, the step of, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Is used for measuring the voltage value of the non-injection impedance, Is the frequency point The non-injection impedance measurement current value of (a).
3. 3. The method of claim 1, wherein the injection impedance measurement impedance values are as follows: In the above-mentioned method, the step of, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Is used for measuring the voltage value of the injection type impedance, Is the frequency point Is used for measuring the current value of the injection type impedance.
4. 4. The method of claim 1, wherein fusing the non-injected impedance measurement impedance value and the injected impedance measurement impedance value comprises: And carrying out weighted fusion on the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value, wherein the sum of weights of the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value is 1.
5. 5. The method of claim 4 wherein the final impedance measurement is as follows: In the above-mentioned method, the step of, For the final value of the impedance measurement, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Weight coefficient of (c) in the above-mentioned formula (c).
6. 6. The method of claim 5, wherein the process of obtaining the weight coefficients of the frequency bins comprises: When the frequency point Is higher than a first preset threshold and frequency points When the signal-to-noise ratio of the injected data is lower than a second preset threshold value, the frequency point The weight coefficient of (2) is 1; When the frequency point Is higher than a first preset threshold and frequency points Non-injected data loss or frequency bin of (a) When the signal-to-noise ratio of the non-injected data is lower than a second preset threshold value, the frequency point The weight coefficient of (2) is 0; When the frequency point Non-injected data signal to noise ratio and frequency bins When the signal-to-noise ratio of the injected data is higher than a first preset threshold value, the initial frequency point The weight coefficient of (2) is 0.5, and for frequency points Dynamically updating the weight coefficient of the (C).
7. 7. The method of claim 6, wherein the non-injected data signal-to-noise ratio of the frequency bins is as follows: In the above-mentioned method, the step of, Is the frequency point Is a non-injected data signal to noise ratio, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Non-injected impedance measurement noise of (a).
8. 8. The method of claim 6, wherein the injected data signal-to-noise ratio at the frequency bin is as follows: In the above-mentioned method, the step of, Is the frequency point Is used for the injection type data signal-to-noise ratio, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Is used for the noise of the injection type impedance measurement value.
9. 9. The method of claim 6, wherein the weight coefficients of the frequency bins are dynamically updated as follows: In the above-mentioned method, the step of, Is the frequency point Is used for the injection type data signal-to-noise ratio, Is the frequency point Is a non-injected data signal to noise ratio, Is a scale factor.
10. 10. A device for measuring broadband impedance of a power distribution network, the device comprising: The acquisition module is used for acquiring a non-injection type impedance measurement impedance value and an injection type impedance measurement impedance value of the power distribution network; and the fusion module is used for fusing the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value to obtain an impedance measurement final value.
11. 11. The apparatus of claim 10, wherein the non-injected impedance measurement impedance values are as follows: In the above-mentioned method, the step of, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Is used for measuring the voltage value of the non-injection impedance, Is the frequency point The non-injection impedance measurement current value of (a).
12. 12. The apparatus of claim 10, wherein the injection impedance measurement impedance values are as follows: In the above-mentioned method, the step of, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Is used for measuring the voltage value of the injection type impedance, Is the frequency point Is used for measuring the current value of the injection type impedance.
13. 13. The apparatus of claim 10, wherein the fusing the non-injected impedance measurement impedance value and the injected impedance measurement impedance value comprises: And carrying out weighted fusion on the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value, wherein the sum of weights of the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value is 1.
14. 14. The apparatus of claim 3 wherein the final impedance measurement is as follows: In the above-mentioned method, the step of, For the final value of the impedance measurement, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Weight coefficient of (c) in the above-mentioned formula (c).
15. 15. The apparatus of claim 14, wherein the process of obtaining the weight coefficients for the frequency bins comprises: When the frequency point Is higher than a first preset threshold and frequency points When the signal-to-noise ratio of the injected data is lower than a second preset threshold value, the frequency point The weight coefficient of (2) is 1; When the frequency point Is higher than a first preset threshold and frequency points Non-injected data loss or frequency bin of (a) When the signal-to-noise ratio of the non-injected data is lower than a second preset threshold value, the frequency point The weight coefficient of (2) is 0; When the frequency point Non-injected data signal to noise ratio and frequency bins When the signal-to-noise ratio of the injected data is higher than a first preset threshold value, the initial frequency point The weight coefficient of (2) is 0.5, and for frequency points Dynamically updating the weight coefficient of the (C).
16. 16. The apparatus of claim 15, wherein the non-injected data signal-to-noise ratio for the frequency bins is as follows: In the above-mentioned method, the step of, Is the frequency point Is a non-injected data signal to noise ratio, Is the frequency point Is used for measuring the impedance value of the non-injection type impedance, Is the frequency point Non-injected impedance measurement noise of (a).
17. 17. The apparatus of claim 14, wherein the injected data signal-to-noise ratio for the frequency bins is as follows: In the above-mentioned method, the step of, Is the frequency point Is used for the injection type data signal-to-noise ratio, Is the frequency point Is used for measuring the impedance value of the injection type impedance, Is the frequency point Is used for the noise of the injection type impedance measurement value.
18. 18. The apparatus of claim 14, wherein the weight coefficients for the frequency bins are dynamically updated as follows: In the above-mentioned method, the step of, Is the frequency point Is used for the injection type data signal-to-noise ratio, Is the frequency point Is a non-injected data signal to noise ratio, Is a scale factor.
19. 19. A computer apparatus, comprising: one or more processors; the processor is used for executing one or more programs; The method for measuring broadband impedance of a power distribution network according to any one of claims 1 to 9, when said one or more programs are executed by said one or more processors.
20. 20. A computer-readable storage device, on which a computer program is stored, which computer program, when executed, implements a method for measuring broadband impedance of a power distribution network according to any one of claims 1 to 9.

Description

Method and device for measuring broadband impedance of power distribution network Technical Field The invention relates to the technical field of power, in particular to a method and a device for measuring broadband impedance of a power distribution network. Background With the wide access of high-proportion renewable energy sources, energy storage systems and various power electronic source loads in the power distribution network, the structural form and the operation characteristics of the power distribution network are deeply changed. The rapid control response of the power electronic equipment interacts with the power grid, so that the stability problems of harmonic resonance, broadband oscillation and the like of the power distribution network are increasingly prominent. Under the background, the broadband domain impedance characteristic becomes a key index for analyzing the stability of the system, evaluating the grid-connected performance of new energy and positioning a resonant source. The broadband impedance characteristic of the power distribution network is accurately obtained, and the method has important significance for guaranteeing the safe, stable and high-quality operation of the power grid. Currently, impedance measurement methods for power distribution networks are mainly classified into non-injection measurement and injection measurement. The non-injection measurement method utilizes inherent disturbance events such as load switching and the like in a power distribution network as an excitation source, and calculates the system impedance by measuring the voltage and current response at a public connection point and adopting a frequency domain analysis method. The method does not need an external excitation device, has no interference to the operation of the power grid, but has the limitations that (1) the effective frequency band of impedance measurement completely depends on the frequency spectrum characteristic of a natural disturbance event, has the defect of frequency band deficiency, (2) the signal quality is poor, the amplitude and the frequency of the natural disturbance signal are random and uncontrollable, the signal to noise ratio is often lower, and (3) the measurement is required to wait for the occurrence of a specific disturbance event, lacks the initiative and is difficult to meet the real-time or on-demand measurement requirement. The injection type measuring method comprises the steps of actively injecting a known broadband signal with limited amplitude into a power grid through power electronic equipment, measuring voltage and current response of a system, and calculating impedance through frequency domain analysis. The method has the advantages of controllable excitation signal, high accuracy of measurement results and continuous and complete frequency band. There are also inherent drawbacks in that ① presents potential disturbances to the system, although the injection signal amplitude is small, it may have unpredictable negative effects on sensitive loads, relay protection equipment, and power quality, and in that the ② model idealizes errors in that the measurement results are based on an ideal injection signal model and linear system assumptions. In practical application, the nonlinear characteristics, coupling impedance, background harmonic and other factors of power electronics can introduce errors, so that the measurement result deviates from the actual running state of the system, and ③ usually requires additional special signal injection equipment, thereby increasing the complexity and implementation cost of the system. In summary, the existing single measurement technology has inherent defects that the non-injection method is difficult to completely grasp the broadband impedance characteristic of the system, and the injection method can grasp the broadband characteristic but may introduce interference to the system and have model distortion problems. Both have a contradiction between band coverage, measurement accuracy and impact on the system. Disclosure of Invention In order to overcome the defects, the invention provides a method and a device for measuring broadband impedance of a power distribution network. In a first aspect, a method for measuring broadband impedance of a power distribution network is provided, where the method for measuring broadband impedance of the power distribution network includes: Acquiring a non-injection type impedance measurement impedance value and an injection type impedance measurement impedance value of the power distribution network; and fusing the non-injection type impedance measurement impedance value and the injection type impedance measurement impedance value to obtain an impedance measurement final value. Preferably, the non-injection impedance measurement impedance value is as follows: In the above-mentioned method, the step of, Is the frequency pointIs used for measuring the impedance value of the non-injection typ