基于相位补偿的直流配电系统频振荡抑制策略

doi:10.19595/j.cnki.1000-6753.tces.241488

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Abstract

With the access of a large number of distributed power supplies and various types of DC loads, the distribution of power electronic equipment in the DC distribution system becomes more concentrated, leading to the inertia and damping of the system being reduced, which makes it easy that small-signal stability problems occur, divided into low-frequency oscillation and high-frequency oscillation. Among them, the problem of low-frequency oscillation caused by the negative impedance characteristic of constant power load has been concerned and solved widely. However, with the substantial growth of power supply demand of AI cluster computing and so on, the system power supply density requirements are increased correspondingly, so the input capacitance of the converter is reduced constantly, making the impedance mismatch point move to the high-frequency band gradually. Because the digital control is flexible and reliable, it is often used for the control of converters, which makes the high-frequency oscillation problem become more and more prominent. Therefore, in order to promote the improvement of the next generation of high-density and high-efficiency power supply, the high-frequency oscillation problem in the DC distribution system needs to be solved.
To solve this issue, the mechanism of high-frequency oscillation in DC distribution system was analyzed. Firstly, considering the influence of each link in the digital control loop of the actual system, the modified small- signal model of the load converter impedance was constructed, making the accuracy range of the model be extended to the kHz level. Secondly, based on the modified model, the stability problem of DC distribution system was further analyzed, and the classification of low-frequency oscillation and high-frequency oscillation of small-signal oscillation problem was proposed, and the main factors of high-frequency oscillation problem were analyzed. The digital control delay includes control delay and voltage and current sampling delay, in which the calculation delay is the main factor affecting the stability of the system, the current loop sampling delay is the second, and the voltage loop sampling delay can be negligible.
A phase compensation-based high-frequency oscillation suppression method was proposed for DC power distribution system. Firstly, the phase compensator was added to the control loop to compensate the dominant factor of high-frequency oscillation in DC distribution system. Secondly, the compensator parameters were designed to compensate the phase of the system in the high-frequency band and improve the stability of the system, so as to solve the high-frequency oscillation problem in the DC distribution system. Finally, the influence of the added strategy on the stability and dynamic performance of the system was analyzed theoretically.
The experimental results based on 3kW, 240-400V experimental platform validated the correctness of the stability analysis results and the performance of the phase compensation strategy. The results show that the proposed small-signal model of modified impedance converter can reflect the digital control link in the actual system, and ensure the accuracy of the system modeling in high-frequency band. At the same time, the proposed phase compensation strategy can improve the small-signal stability of DC distribution system, solve the problem of high-frequency oscillation of cascaded DC system, and ensure the excellent dynamic performance of the system. In addition, when the load power, input voltage, switching frequency or equivalent inductance of the cable changes, the proposed control strategy can ensure good stability and robustness of the system.

Key words： Phase compensation DC distribution power system high-frequency oscillation small-signal stability digital control

Received: 23 August 2024

PACS:	TM721.1
	TM712

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	Wang Tonglu
	Wang Yue
	Fan Youlin
	Li Yufei
	Zhao Bi'an

Cite this article:

Wang Tonglu,Wang Yue,Fan Youlin等. A Phase Compensation-Based High-Frequency Oscillation Suppression Method for DC Power Distribution Systems[J]. Transactions of China Electrotechnical Society, 0, (): 1488-9.

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https://dgjsxb.ces-transaction.com/EN/10.19595/j.cnki.1000-6753.tces.241488 OR https://dgjsxb.ces-transaction.com/EN/Y0/V/I/1488

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