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无电解电容多端口变换器的低频直流母线电流纹波抑制控制策略

Control Strategy for Multi-Port Converters Without Electrolytic Capacitors to Mitigate Low-Frequency DC-Link Current Ripple Effects

  • 摘要: 多端口变换器(MPC)因其控制灵活、功率密度高的特性,应用范围正不断扩大。但光伏系统输出电流及直流母线电流波动与低频纹波,会影响系统稳定性,同时导致功率因数降低。针对上述问题,可采用的解决手段包括改进控制技术、负载转移、需求削峰、优化功率管理以及提升可再生能源的并网适配性等。本文首先提出一种改进扰动观察法(MP O)与比例积分控制(PI控制)相结合的控制策略,通过调控光伏直流变换器的占空比,实现最大功率点跟踪(MPPT)。其次,提出一种简洁的d-q轴电流管理方法,基于流程图决策逻辑,实现光伏功率与电池储能系统(BESS)荷电状态(SoC)协同下的直流母线管控。该方法采样频率低,能够实现直流母线控制器的经济性部署。实验结果表明,所提MP O-PI复合控制方法有效抑制了直流母线低频纹波及光伏功率波动,具备更优的纹波抑制能力与动态响应速度。最后,将所提MP O-PI方法与主流先进技术开展对比分析,结果证实该方法可提升系统稳定性、加快响应速度并提高能源利用效率,验证了所提控制框架的可行性与优越性。

     

    Abstract: Multi-port converters (MPCs) are increasingly used for their flexibility in control and high-power density. However, fluctuations and low-frequency ripples in photovoltaic (PV) and DC bus currents can compromise system stability and lead to a reduced power factor. Enhanced control techniques, load moving, demand peaking reducing, optimal power management, and improved incorporation of renewable energy sources may all be used to address these problems. In this paper, Firstly, a modified perturb & observe (MP&O) method combined with PI control is introduced for maximum power point tracking (MPPT) via controlling the duty ratio of the PV DC converter. Secondly, a new and straightforward d-q current management method is used for DC-Bus management in both PV power and the battery energy storage system"s (BESS) state of charge (SoC) using flowchart-based decision logic. This approach ensures cost-effective implementation of the DC?Bus controller due to its low sampling frequency. The proposed MP&O-PI methods reduced the frequency DC bus ripples, and PV fluctuation, showing better suppression ability and dynamic response speed. Finally, a comparative analysis of the proposed MP&O-PI approach with a known state-of-the-art technique demonstrates a system stability improvement, faster response, and improved energy efficiency, approving the efficiency of the proposed control framework.

     

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