Microgrid inverter sagging automatic control method based on small signal stability analysis

Abstract

The invention discloses a microgrid inverter sagging automatic control method based on small signal stability analysis. According to the control method, on the premise that the slope of a P-f sagging curve and the slope of the Q-V sagging curve are actively regulated, the small signal stability analysis is imported, the feasibility of the slopes after being actively regulated is verified, and no-deviating regulation of voltages and frequency is achieved on the premise that stability of a system is guaranteed. Special to distributed generation under sagging control in an islanding state, the requirement of load changes is met by automatically regulating the slopes of the sagging curves and changing a reference active power value corresponding to rated frequency in the sagging curves and a reference reactive power value corresponding to rated voltage, and no-deviating frequency regulation and voltage regulation is achieved; the range of the slopes of the sagging curves allowed under the condition that the system stably operates is obtained through the small signal stability analysis, and when the sagging slopes are automatically regulated, the range needs to be met, and instability of the system caused by the operation for purely achieving the no-deviating frequency regulation and voltage regulation is avoided.

Description

technical field [0001] The invention relates to the field of micro-grid control, in particular to an automatic control method for drooping of a micro-grid inverter based on small-signal stability analysis. Background technique [0002] With the emergence of the energy crisis and the development requirements of energy conservation and emission reduction, microgrids that use a large amount of renewable energy are developing rapidly. The distributed power supply in the microgrid is connected to the grid through power electronic devices. When the large grid fails and the microgrid and the large grid split into an island operation state, the internal distributed power supply needs to provide voltage and frequency support for the microgrid system. , the droop control that simulates the characteristics of synchronous generators is widely used to achieve this goal, such as P-f, Q-V droop control, P-V, Q-f droop control, etc. But for a certain drooping curve, when the load changes, ...

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Problems solved by technology

However, this method does not consider that the droop slope is limited by the constraints of the stable operation of the system, and the automatically adjusted steady-state operating point may lead to unstable operation of the system

[0004] Invention patent (Application No. 201210107053.4) discloses an island grid control and optimization method based on rotating coordinate virtual impedance. Aiming at the complex impedance characteristics in the actual microgrid, the coordinate rotating orthogonal transformation is used to design the coordinate rotating virtual impedance to improve the performance of the microgrid. Impedance characteristics, however, this patent is mainly aimed at the calculation, analysis and optimal operation of the steady-state operation of the micro-grid. It does not consider the transient adjustment process of the new energy and load of the micro-grid system in a short period of time. Voltage and frequency adjustment without difference

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