Oscillation and The Suppression Strategy in Microgrid: A Review

As people's demands for the environment and future development, new energy sources such as wind energy, and solar energy have become the trend of the times. At the same time, due to the introduction of clean energy, power electronics and switching devices in the power system are heavily invested in the power network. The investment in areas above has made the stability of the power system suffering more tests, and the instability and oscillation of the power system have intensified. Therefore, this paper first analyzes the mathematical model of power system oscillation. The existing oscillation causes and suppression methods of traditional power systems are summarized. Then the causes of the micro-grid oscillation of the distributed power supply with high permeability are analyzed in detail. The difference from the traditional power system oscillation is that the traditional power network oscillation is caused by the shafting torsional vibration of the rotating electrical machine. The vibration reacts, which may cause the damping torque of the unit in the corresponding torsional vibration mode to weaken or even become negative, causing oscillation. Or rotary electric machines (including synchronous/asynchronous power generation/motors) and power electronic converters may exhibit an "induction generator/negative resistance" effect on the electrical oscillation mode under certain operating conditions, when the negative resistance exceeds the total positive resistance of the grid, resulting in The LC oscillates and diverge. The reason for the power electronic oscillation is the coupling oscillation between the power electronic converters or the network generated by the interaction with the AC grid. This kind of oscillation is difficult to find the existing fixed model to apply, because the power electronic device has a fast response speed and low Inertia, unlike traditional motors, oscillations are more likely to occur in high frequency bands and have more features. Based on this, different research methods and speculations on the causes of microgrid oscillations at home and abroad are summarized. Due to different causes, the methods used to suppress system oscillations are summarized and described. Finally, the content of the full text is summarized. Prospects for the future development of microgrid oscillation research.