电网电压不平衡工况下，风光储一体化系统中设备间存在复杂相互作用，电磁振荡风险显著提升。为抑制该工况下系统的负序电压，并提高系统稳定性，该文首先建立适用于风光储系统的线性周期时变（linear time-periodic, LTP）模型，该方法充分计及了电压不平衡工况下时变耦合量，较经典的线性时不变（linear time-invariant, LTI）分析准确性更高。在LTP模型基础上，该文综合对比了当并网换流器采用正序单锁相环或正负序双锁相环时系统的小信号稳定性，指导两类控制策略的适用范围，提出自适应锁相环切换控制；以及研究了新能源并网国家标准规范下的负序无功电流系数对系统小信号稳定性的影响规律，指导负序无功电流系数取值，实现了系统负序电压的有效抑制的同时保证稳定性裕度。

Under grid voltage imbalance conditions, the complex interactions among equipment in integrated wind-photovoltaic-energy storage systems significantly increase the risk of electromagnetic oscillations. To suppress negative-sequence voltage and enhance system stability under such conditions, this paper first establishes a linear time-periodic (LTP) model tailored for wind-PV-storage systems. This method fully accounts for time-varying coupling quantities under voltage imbalance, offering higher accuracy compared to classical linear time-invariant (LTI) analysis. Based on the LTP model, the paper comprehensively compares the small-signal stability of the system when grid-connected converters adopt either a positive-sequence single phase-locked loop (PLL) or a positive/negative-sequence dual PLL, guiding the applicable scope of these two control strategies and proposing an adaptive PLL switching control. Furthermore, it investigates the impact of the negative-sequence reactive current coefficient, as specified by national standards for renewable energy grid integration, on the system’s small-signal stability. This study provides guidance for selecting the negative-sequence reactive current coefficient, achieving effective suppression of negative-sequence voltage while ensuring sufficient stability margins.