基于前馈功率解耦控制的光伏电站系统稳定性研究

Study on system stability of photovoltaic power stations based on feedforward power decoupling control

在构建以新能源为主体的新型电力系统及能源结构绿色低碳转型的背景下,光伏发电依托大量电力电子器件并网,新能源逐渐取代常规同步机组,对电网稳定运行提出新的挑战。光伏并网逆变器呈现出与电网非线性耦合、动态交互等特性,为电网带来新的扰动因素及安全稳定问题;基于光伏并网逆变器功率双环解耦控制的特点,通过附加额外控制可以提高并网系统的抗扰动能力。推导出了与同步机并列运行的光伏电站附加控制提供正阻尼转矩的机理,设计了基于前馈功率解耦控制(FPD)的并网逆变器阻尼控制策略,通过阻尼转矩系数法推理整定控制器参数来平抑系统的功率振荡。以某实际运行的光伏电站为例,依托Digsilent平台完成光伏电站并入某4机2区域电网建模,仿真验证了所提方法的准确性。

In the context of constructing a new power system with new energy as the main body and realizing the green and low-carbon transition of energy mix, photovoltaic(PV) power stations are connecting to the power grid relying on a large number of power electronic devices. New energy gradually replaces conventional synchronous units, posing new challenges to the stable operation of the grid. PV grid-connected inverter shows nonlinear coupling and dynamic interaction with the power grid,which brings new disturbance factors and security problems to the grid.Based on the characteristics of dual loop decoupling control on grid-connected inverter power, the anti-disturbance ability of grid-connected system can be improved by additional target control of PV power stations. The mechanism of the positive damping torque provided by the additional control of PV power stations running in parallel with the synchronous machine is deduced. The additional damping control strategy for grid-connected inverters based on the feedforward power decoupling control(FPD) is designed.The controller parameters are adjusted by the damping torque coefficient method to suppress the power oscillation of the system. Taking a PV power station as an example, the modeling of PV power station merging into a "four unit two area" power grid was completed on Digsilent platform, and the accuracy of the proposed method was verified by simulation.