随着新型电力系统源网荷储协同一体化发展，分布式光伏并网规模的不断扩大，弱电网条件逐渐形成，同时多台逆变器接入配电网末端构成复杂阻抗网络，导致并网系统阻抗特性发生变化，同时增加了系统的谐振风险。为研究弱电网条件下分布式光伏并网系统谐振特征，通过建立系统等效阻抗模型分析关键参数对谐振特性的影响。首先，建立了计及电流内环、电容电流前馈、控制系统延时的逆变器诺顿等值模型。然后，考虑弱电网条件下公共耦合点（point of common coupling, PCC）处负荷特性对系统谐振的影响，构建了表征多并网逆变器、本地负荷、线路以及交流电网等关键设备阻抗交互耦合的分布式光伏并网系统等效模型；进一步，提出了反映逆变器谐波电流以及网侧背景谐波电压等多源谐波扰动对并网电流谐振激励作用的映射模型，揭示了电网阻抗、光伏输出功率、并网逆变器数量变化对系统谐振特性的影响规律。最后，通过仿真验证了所提光伏并网系统等效模型的准确性并分析了相关因素对光伏并网谐振特性的影响。 

With the "source-grid-load-storage integration" and large-scale integration of distributed photovoltaic (PV), the grid condition is gradually presenting as a weak grid. Furthermore, multiple inverters are connected to the end of the distribution network to form a complex impedance network that increases the risk of resonance. To investigate the resonance mechanism of a distributed PV system under a weak grid, the Norton model of the inverter, considering the current loop, capacitive current feedforward, and control delay, is derived. Then, considering the influence of the load at the point of common coupling (PCC) on the system impedance characteristics under a weak grid, an equivalent model of a grid-connected system that can reveal the impedance matching relationship between multiple inverters, local loads, and the grid is established under weak grid conditions. Furthermore, a mapping model is proposed to reflect the excitation effect of the harmonic current of the inverter and the background harmonic voltage of the grid side on the resonance of the grid-connected current. The influence of the grid impedance, PV output power, and number of inverters on the resonance characteristics of the grid-connected system is revealed. Finally, the accuracy of the proposed equivalent model is verified through a simulation, and the influence of relevant factors on the PV grid-connected system is analyzed.

风电的高比例渗透削弱了电力系统的惯性与调频容量，储能凭借响应迅速、出力稳定等特点被广泛应用于电网的惯量支撑及频率调节工作。首先以双馈风机额定转速与有功出力为约束条件，基于转子超速控制设置最适功率预留系数，划分风机参与系统调频的风速范围。在此基础上，考虑系统频率支撑能力，提出一种风电机组与储能协调配合的调频方法。通过对储能有功出力与系统稳态恢复过程的分析，刻画了虚拟同步机控制策略下储能系统的动态频率调节特性，由此实现储能在应对系统不同工况与不同支撑需求下控制参数的最优配置。仿真结果表明，所提方法能够在保证系统调频需求的同时充分利用风电自身的调频容量，优化储能系统参数的配置结果，实现储能出力的平滑输出，提高系统的频率支撑能力。

The high proportion penetration of the wind power weakens the inertia and frequency regulation capacity of the power system. The energy storage system (ESS) is widely used in the inertia support and frequency regulation of the power grid with the characteristics of rapid response and stable output. Firstly, the rated speed and active power output of the doubly fed induction generator (DFIG) were taken as constraint conditions, and the optimal power reservation coefficient was set based on the rotor overspeed control to divide the wind speed range of the DFIG participating in the system frequency modulation. On this basis, considering the frequency support capacity of the system, a coordinated frequency modulation method of the DFIG and the ESS was proposed. Based on the analysis of the ESS active power output and system steady-state recovery process, the dynamic frequency regulation characteristics of the ESS under the control strategy of the virtual synchronous machine were described, so as to realize the optimal configuration of the control parameters of the ESS under different working conditions and different support requirements. Simulation results show that the proposed method can make full use of the frequency modulation capacity of the DFIG while ensuring the frequency modulation requirements of the system, optimize the configuration results of the ESS parameters, realize the smooth output of the ESS, and improve the frequency support ability of the system.