光储直流配电网灵活虚拟惯性控制策略

Flexible virtual inertial control strategy of photovoltaic-energy storage DC distribution network

针对光伏渗透率不断提高而带来的直流配电网惯性低的问题,考虑直流配电网储能设备的潜在惯性支持能力,提出光储直流配电网灵活虚拟惯性控制策略。分析了在直流配电网电压动态变化过程中蓄电池储能与电压变化量之间的关系,并通过建立蓄电池荷电状态与直流电压的函数表达式,进一步提出了在直流电压变化时引入双曲正切函数来灵活快速调节蓄电池换流器的控制策略,从而增加系统惯性,提高电能质量。另外,还考虑了蓄电池的充放电极限问题,通过引入反正切函数来限制其过度充放电。最后,对采用灵活虚拟惯性控制策略的直流配电网进行小信号稳定性分析,得到了所提控制策略中关键参数的取值范围。基于MATLAB/Simulink搭建了四端直流配电网仿真系统,验证了在系统功率不平衡后,所提控制策略能利用虚拟惯性控制有效地抑制直流电压波动,从而提高电压质量和暂态稳定性。

Aiming at the problem of low inertia of DC distribution network caused by the continuous in⁃crease of photovoltaic penetration rate,a flexible virtual inertia control strategy for photovoltaic-energy storage DC distribution network is proposed considering the potential inertia support capacity of energy storage equipment in DC distribution network.The relationship between battery energy storage and voltage varia⁃tion in the dynamic process of DC distribution network voltage changes is analyzed,and the functional expression for state of charge of battery and DC voltage is established.Furthermore,a hyperbolic tangent function is introduced when DC voltage changes to flexibly and quickly adjust the control strategy of the battery converter,so as to increase the system inertia and improve the power quality.Meanwhile,considering the charging and discharging limit of the battery,the excessive charging and discharging of battery is restricted by introducing the arctangent function.Finally,the small-signal stability analysis of DC distribution network using the flexible virtual inertial control strategy is adopted,and the value range of key parameters in the proposed control strategy is obtained.A four-terminal DC distribution network simulation system is established based on MATLAB/Simulink,and it is verified that the proposed control strategy can effectively suppress DC voltage fluctuation by using virtual inertia control after system power is unbalanced,thereby improving voltage quality and transient stability.