基于无差调压U-I下垂的同步定频微网控制策略研究

Research on synchronous fixed-frequency microgrid control strategy based on zero-error voltage regulating U-I drooping

针对微网孤岛运行时传统电压-电流(U-I)下垂控制中存在的电压偏差以及功率分配不均衡问题,提出一种基于无差调压U-I下垂的同步定频控制策略。该策略利用同步相量测量装置(PMU)为微网内分布式电源逆变器提供全局同步参考信号,实现同步定频运行;在U-I下垂控制的基础上,通过电压偏差调节环节,将下垂曲线平移实现二次调压;根据PMU的量测信息,实时计算受控逆变器出口到并网点间线路阻抗,通过设置虚拟阻抗对线路进行补偿,减小线路阻抗不一致时因二次调压对功率分配造成的不利影响,实现高精度的功率分配。最后,通过Matlab/Simulink仿真模型验证了所提出控制策略的有效性。

In view of the voltage deviation and unbalanced power distribution in the traditional voltage-current(U-I)drooping control during microgrid isolated island operation,a synchronous fixed-frequency control strategy based on zero-error voltage regulating U-I drooping is proposed.In this strategy,a synchronous phasor measurement unit(PMU)is used to provide a global synchronization reference signal for the distributed power inverter in the microgrid to achieve synchronous fixed-frequency operation.On the basis of U-I drooping control,the drooping curve is translated to realize the secondary voltage regulation by the voltage deviation adjustment.On the basis of the PMU measured information,the line impedance between the outlet of the controlled inverter and the grid-connected point is calculated in real time.The line is compensated by setting a virtual impedance.The adverse impact of the secondary voltage regulation on the power distribution is reduced when the line impedance is inconsistent,so as to realize high-precision power distribution.A simulation model is established by Matlab/Simulink to verify the effectiveness of the proposed control strategy.