光伏电站自备用可调的虚拟同步控制调频策略

Virtual Synchronous Control Frequency Regulation Strategy for Adjustable Self-standby Rate in Photovoltaic Plants

采用自备用控制的光伏电站能够为电网提供调频能力,但现有的自备用控制难以评估最大功率,调频经济性需要量化,且无法提供虚拟惯量,光伏电站调频效果有待提高。针对此问题,提出光伏电站自备用可调的虚拟同步调频控制策略。首先,基于光伏运行P-V特性,提出光伏最大功率估算策略以及变步长电压控制策略,实现光伏自备用控制;其次,基于虚拟同步控制策略和光伏电站架构,引入频率反馈控制环,提出光伏自备用可调的虚拟同步控制策略,光伏电站在提供频率响应功率的同时,以虚拟惯量的形式支撑电网的频率稳定。此外,并联在光伏直流侧的储能,可以保证在光伏自备用率动态调整过程中直流侧母线电压的稳定。进一步分析了最大功率估算算法误差对虚拟同步调频控制策略的影响,以及虚拟同步控制参数变化对调频效果的影响。最后,通过Simulink仿真验证了所提控制策略的有效性,为光伏并网调控提供理论支撑。

The photovoltaic plants controlled by self-standby can provide frequency regulation capability for the power grid.But the existing self-standby control is difficult to evaluate the maximum power and and the economy is required to be quantified.Additionally,it can not provide virtual inertia.The effect of frequency regulation response of photovoltaic plants needs to be improved.To address this problem,this paper proposes a virtual synchronous FR control strategy for PV power plants with adjustable self-standby.Firstly,based on the P-V operation characteristics of PV,a PV maximum power estimation strategy is proposed,as well as a variable step voltage control strategy to achieve PV self-standby control.Second,based on the virtual synchronous generator control strategy and the photovoltaic plant architecture,the frequency feedback control loop is introduced.And the photovoltaic self-standby adjustable control strategy is proposed,supporting the frequency stability of the power grid in the form of virtual inertia.In addition,energy storages connected in parallel on the DC side of the photovoltaic ensure the stability of the DC bus voltage during the dynamic adjustment of the photovoltaic operating point with the self-backup rate.The influence of the error of the maximum power estimation algorithm on the virtual synchronous frequency control strategy is further analyzed.And the influence of the change of virtual synchronous control parameters on the frequency modulation effect is discussed.Finally,Simulink simulation results verify the effectiveness of the proposed control strategy and provide theoretical support for the grid-connected regulation of PV.