含异构微源孤岛微电网暂态失稳分析与稳定策略研究

Transient Instability Analysis and Its Stability Strategies for Islanded Microgrid With Heterogeneous Micro-source

为了提高微电网的惯性,分布式可再生能源常采用虚拟同步发电机方式接入,组成与传统同步发电机并联运行的异构微源系统。由于2种微源在物理结构、动态特性等方面存在显著差别,易导致孤岛微电网在大扰动下出现功频振荡等暂态失稳问题。该文首先建立异构微源并联系统摇摆方程,分析其在大扰动下的暂态失稳机理;进一步,提出基于模型预测的虚拟同步发电机(virtualsynchronousgenerator,VSG)附加转矩控制方法,并给出主要控制参数的选取原则,利用并联系统的角频率增量和转矩增量作为输入来减弱微源之间特性差异的影响,从而提升系统暂态稳定性;最后,通过MATLAB/Simulink仿真及StarSim硬件在环半实物实验,验证该文理论分析及控制方法的正确性、有效性及优越性。

To improve the inertia of the microgrid,some distributed renewable energy sources are often connected in as the virtual synchronous generators to form a heterogeneous micro-source system operating in parallel with the conventional synchronous generators.Due to the remarkable differences in their physical structures and dynamic characteristics of these two micro-sources,they are prone to some transient instability problems such as the power-frequency oscillations in the isolated microgrids under a large disturbance.In this paper,the oscillating equations of the parallelled system with the heterogeneous micro-sources are established to analyze the transient instability mechanism of the system under the large disturbance;Furthermore,the VSG additional torque control method based on the model prediction is proposed,and the selection principle of the main control parameters is given.The angular frequency and its torque increments of the parallelled system are used as the input to attenuate the effects of the differences in their characteristics between the micro-sources so as to improve the transient stability of the system.Finally,the correctness and effectiveness of the theoretical analysis and the control method are verified in the MATLAB/Simulink simulation and the StarSim hardware-in-the-loop semi-physical experiments.