基于实时最大功率估计的光伏系统参与电网调频的控制策略

Control Strategy for Photovoltaic System Participating in Power Grid Frequency Modulation Based on Real-time Maximum Power Estimation

光伏电源本身存在非线性特性明显、缺少惯性等不足,大规模接入电网会导致电网频率波动。为此,提出基于实时最大功率估计的光伏系统参与电网调频的控制策略。该控制策略能够较为准确地估计最大可用功率,调节输出功率,并根据调频的定量需求反向调节光伏系统的减载率,使光伏系统有效地参与电网的一次调频与二次调频,从而改善光伏并网后的系统频率波动。通过算例仿真,从光伏减载算法、光伏渗透率的影响、下垂系数和虚拟惯性值的影响几个方面验证了所提控制策略的有效性。

Large-scale access of photovoltaic power will cause fluctuation of power grid frequency due to its shortages such as obvious nonlinear characteristics and lack of inertia. Thus, this paper proposes a control strategy for the photovotaic system participating in frequency modulation of the power grid based on real-time maximum power estimation. This strategy can relatively precisely estimate the maximum available power, adjust output power and modulate load shedding rate of the photovoltaic system in reverse according to quantitative demand of frequency modulation so as to make the photovoltaic system effectively participate in primary and secondary frequency modulation of the power grid and improve system frequency fluctuation after photovoltaic grid-connection. Example simulation verifies effectiveness of the proposed strategy in the aspects including the photovoltaic load shedding algorithm, influence of photovoltaic permeability, drop coefficient and virtual inertia values.