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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摘要

直流配电系统中电力电子设备分布集中,总体呈现弱阻尼特性,易引发一系列小信号稳定性问题,随着AI集群计算等供电需求的大幅增长,供电密度相应提升,使得阻抗不匹配点逐渐向高频段移动,尤其是数字控制延时所导致的高频振荡问题逐渐凸显。针对此问题,本文提出一种基于相位补偿器的直流配电系统高频振荡抑制策略,首先考虑了系统中的数字控制延时,构建级联直流系统的修正阻抗小信号模型,提升高频段建模结果的准确性;其次,基于修正模型,对配电系统进行了高频振荡机理的分析;最后,考虑高频振荡的主要影响因素,提出了相位补偿器策略,通过修改系统的控制回路重塑负载变换器的闭环输入阻抗,对直流配电系统中的高频振荡进行有效抑制,提升系统的供电稳定性。在240V直流配电系统中对该方法进行了测试,实验结果验证了系统稳定性分析结果的正确性以及相位补偿策略的性能。

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关键词 ：相位补偿, 直流配电系统, 高频振荡, 小信号稳定性, 数字控制

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

收稿日期: 2024-08-23

PACS:	TM721.1
	TM712

通讯作者: 王跃, 男,1972年生,教授,博士生导师,研究方向为新能源变流器控制与稳定性分析、柔性直流输电等。E-mail：davidwangyue@mail.xjtu.edu.cn

作者简介: 王彤鹭, 女,2000年生,硕士研究生,研究方向为直流配电系统的阻抗建模、控制及稳定性分析。E-mail：tlwang@stu.xjtu.edu.cn

引用本文:

王彤鹭, 王跃, 樊囿麟, 李宇飞, 赵笔安. 基于相位补偿的直流配电系统频振荡抑制策略[J]. 电工技术学报, 0, (): 1488-9. Wang Tonglu, Wang Yue, Fan Youlin, Li Yufei, Zhao Bi'an. A Phase Compensation-Based High-Frequency Oscillation Suppression Method for DC Power Distribution Systems. Transactions of China Electrotechnical Society, 0, (): 1488-9.

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