基于波动特性解析的配电系统阻抗辨识方法

doi:10.19595/j.cnki.1000-6753.tces.250014

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Abstract With the continuous promotion of low-carbon transformation of green energy, a high proportion of distributed power sources are connected to the power grid, and the traditional single-radiation network becomes a source-load interactive multi-source network. The system operation mode changes in a wide range, resulting in a huge challenge for the staged current protection based on single-source fault characteristics. Although the existing adaptive protection technology improves flexibility by adjusting the protection setting value in real time, its core depends on accurate system equivalent impedance identification. However, the traditional identification method has significant errors under complex conditions such as new energy output fluctuation, multi-source coupling and internal disturbance of the system. Especially when the load side interacts with the distributed power supply on the system side, the failure of traditional assumptions leads to a sharp decline in identification accuracy. Aiming at the above problems, this paper proposes an impedance identification method based on fluctuation characteristic analysis. By reconstructing the mathematical model, optimizing the algorithm framework and multi-scenario verification, the system solves the problem of protection adaptability of high-proportion new energy distribution network.
Traditional impedance identification methods can be divided into two categories based on network information and local information. The former relies on global topological parameters and has defects such as complex calculation and difficulty in online application. Although the latter uses local measurement information, the least square method, covariance method and other algorithms increase the error due to ignoring the potential fluctuation component and coupling effect in the new energy disturbance scenario. This paper innovatively proposes to decompose the equivalent potential of the system into a superposition model of steady-state value and fluctuation value, which breaks through the limitations of traditional methods on the assumption of constant potential or single variable. By analyzing the dynamic correlation between the fluctuation component and the system impedance, the impedance identification equation considering the coupling of multi-source disturbances is established, and the improved forgetting factor algorithm is used to dynamically adjust the weight of historical data, which effectively suppresses the influence of the algorithm itself.
In the scenario of system-side potential fluctuation of ± 0.2% and ± 0.4% and load-side impedance disturbance of ± 5%, the method in this paper stabilizes the resistance and reactance identification errors within 5% and 3% respectively through the potential steady-wave decoupling model, which is more than 50% lower than the traditional method. For the sudden change of system impedance, the maximum tracking error of resistance and reactance of the proposed algorithm is only 4.34% and 1.08%. Aiming at the two-way coupling problem caused by the penetration of distributed power supply on the load side, a test scenario with 2 600 kW load side photovoltaic is constructed. The traditional method leads to an error of more than 15% due to source-load coupling, while the phase decoupling strategy in this paper reduces the average error to 0.92%. When the load impedance fluctuation is 10%, the maximum error of the improved forgetting factor method is reduced from 50% to 14%, and the average error is less than 5%. Experiments show that the proposed method meets the national standard requirements in the scenarios of new energy fluctuation, topology change and multi-source coupling, and provides high-precision parameter support for adaptive protection.

Key words： Impedance identification system perturbation wave characteristics improved forgetting factor method

Received: 02 January 2025

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TM711

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	Articles by authors
	Deng Bang
	Jia Ke
	Bi Tianshu
	Chen Xingyi
	Kong Jiajing

Cite this article:

Deng Bang,Jia Ke,Bi Tianshu等. Impedance Identification Method of Distribution System Based on Fluctuation Characteristic Analysis[J]. Transactions of China Electrotechnical Society, 2026, 41(3): 938-948.

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https://dgjsxb.ces-transaction.com/EN/10.19595/j.cnki.1000-6753.tces.250014 OR https://dgjsxb.ces-transaction.com/EN/Y2026/V41/I3/938

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