基于虚拟功角功率控制的VSG增强功率解耦策略

Enhanced Power Decoupling Strategy for VSG With Power Control Based on Virtual Power Angle

虚拟同步机可提升“双高”电力系统惯性,但其存在的固有功率强耦合会产生功率稳态误差,严重限制变流器功率传输能力,甚至导致系统失稳。为此,该文详细分析VSG功率耦合机理,指出线路阻感比R/X与功角θ是影响功率耦合两大因素,并评估其引起的功率耦合对稳定性影响。然后在虚拟电感控制基础上考虑R/X和θ,提出一种基于虚拟功角的功率控制策略,使用理论公式计算虚拟功角值改进功率环控制,增强了大范围功角情况下功率解耦效果,抑制了无功功率波动,并用幅相运动方程判据评估该系统稳定性。最后,通过理论分析和实验结果验证所提解耦控制策略的有效性。

The adoption of virtual synchronous machines can enhance the system inertia of a“double high”power grid.However,the strong reactive power coupling inherent in the virtual synchronous machines can introduce power steady-state errors,significantly restricting the power transmission capacity of the converter,and potentially leading to system instability.Therefore,this paper conducts a detailed analysis of the power coupling mechanism of the VSG,and identifies the line impedance ratio(R/X)and phase angle(θ)as the two major factors that affect power coupling.The impact of the power coupling on stability is evaluated in this paper.Then,based on the virtual inductance control,a power control strategy based on virtual power angle is proposed,which takes into account both R/X andθ.The virtual power angle value is calculated using theoretical formulas for power loop reshaping,which can eliminate power coupling in multiple scenarios of the VSG,suppress reactive power fluctuations,and evaluate the stability of the system using the amplitude-phase motion equation criterion.Finally,the effectiveness of the proposed decoupling control strategy is validated through theoretical analysis and experimental results.