适用于孤岛微电网的电压型虚拟同步发电机自适应惯性控制与频率恢复控制

孤岛微电网惯性水平低,频率稳定问题显著。基于此,提出了适用于孤岛微电网电压型虚拟同步发电机(voltage-controlled virtual synchronous generators,VSGs)的自适应惯性与频率恢复控制方法,用于孤岛微电网频率稳定性提升。在自适应惯性控制方面,利用转速偏差及其变化率刻画频率动态过程,分别构建其与虚拟惯性的关系;利用双曲正弦函数放大虚拟惯性对转速偏差及其变化率的灵敏度,提高控制的敏感性;引入sigmoid函数,限制虚拟惯性调节范围,抑制控制过程中VSG输出功率的振荡。在频率恢复控制方面,从有功功率供需平衡的角度出发,将频率恢复问题转化为全网有功再平衡问题;利用各台VSG的频率偏差及其变化率估计全网有功再平衡量,并按容量分配每台VSG承担的全网有功再平衡量,实现功率均分。通过不同情境对所提方法进行仿真测试,结果验证了其有效性。

Adaptive Inertia Control and Frequency Recovery Control of Voltage-Controlled Virtual Synchronous Generators for an Isolated Microgrid

In the isolated microgrid,the inertia level is low,and the problem of the frequency stability is obvious.Based on this background,the adaptive inertia and frequency recovery control method for voltage-controlled virtual synchronous generators(VSGs)in isolated microgrid is proposed to improve the frequency stability of the isolated microgrid.In the aspect of adaptive inertia control,the dynamic process of frequency is described by angular frequency deviation and its change rate,and the relationships between them and the virtual inertia is constructed respectively.The sensitivity of the virtual inertia to the changes of angular frequency deviation and its change rate is amplified by the hyperbolic sine function to improve the sensitivity of control.The sigmoid function is introduced to limit the adjustment range of the virtual inertia and suppress the oscillation of VSG output power in the control process.For the frequency recovery control,from the perspective of active power balance between generation and demand,the frequency recovery problem can be transformed into the rebalancing problem of the active power of the whole system.The frequency deviation and its change rate of each VSG are utilized to estimate the rebalancing amount of the active power of the system,and the rebalancing amount of the active power of the system borne by each VSG is allocated to realize power sharing according to the capacity of each VSG.The effectiveness of the proposed method is verified by simulation tests in different scenarios.