基于附加阻尼的微网改进下垂控制方法

Improved Droop Control Method for Microgrid Based on Additional Damping

采用传统有功频率、无功电压幅值下垂控制时,若下垂系数选取不合理,逆变器输出功率会出现持续振荡,当微网离网运行时,逆变器输出功率的振荡会导致微网系统频率出现波动,严重时会使整个系统出现功角稳定性问题。文中基于储能逆变器动态频率特性的概念,根据其产生正阻尼作用的相位条件和幅值条件,提出了基于附加阻尼的改进下垂控制方法。该方法可以在不影响系统稳态频率和逆变器输出功率的前提下,有效地增加系统的阻尼,从而抑制逆变器输出功率振荡,提高系统的稳定性。最后通过PSCAD仿真,验证了所提控制策略的有效性。

When the traditional active power versus frequency and reactive power versus voltage magnitude droop control is applied,if the droop coefficients are irrational,the output power of the inverter will keep oscillating.When the microgrid operates in the islanding mode,the microgrid frequency will fluctuate because of the output power oscillation of the energy storage inverter.When serious,there will be the power angle stability problem.Based on the concept of dynamic frequency-power characteristic,this paper proposes an improved droop control method according to phase condition and magnitude condition of positive damping.The improved droop control can effectively increase system damping to suppress the oscillation of output power of the inverter and improve system stability without affecting the steady state frequency and output power of the inverter.Finally,PSCAD simulation results have validated the feasibility of the proposed method.