A VSG operation mode switching control method

Abstract

The invention discloses a VSG operation mode switching control method. According to the method, in order to realize a purpose of system stable operation, mode change-over switches are respectively added in PI control links of an active / frequency control module and a reactive / voltage control module. By selecting different channels, the active / frequency control module can work both in a traditional VSG active / frequency control mode and in a constant power control mode, so that the reactive power / voltage control module can work in a droop mode as well as serves as a PI controller to enable the output power to follow a set value. According to the invention, through VSG operation mode seamless switching technology, abrupt change of the output voltage frequency is avoided; time needed for system dynamic adjusting and impact brought to a power grid are reduced; and the stable operation of the system is realized.

Description

technical field [0001] The invention belongs to the field of microgrid and distributed power generation, and in particular relates to a VSG operation mode switching control method. Background technique [0002] When the micro-source inverter is connected to the grid, the frequency and amplitude of its output voltage are clamped by the large power grid. When the virtual synchronous generator control technology is used, the micro-source inverter can adjust its output according to the actual needs of the large power grid. active and reactive power to maintain the stable operation of the system. [0003] When the difference between the frequency of the power grid and the rated frequency of the micro-source inverter is large, it is theoretically necessary to output or absorb a large amount of active power to maintain synchronization with the frequency of the large power grid, but the actual capacity of the micro-source inverter is limited. May not meet its standards. When there...

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Problems solved by technology

[0003] When the difference between the frequency of the power grid and the rated frequency of the micro-source inverter is large, it is theoretically necessary to output or absorb a large amount of active power to maintain synchronization with the frequency of the large power grid, but the actual capacity of the micro-source inverter is limited. may not meet its standards

When there is a large difference between the voltage amplitude of the large power grid and the rated voltage amplitude of the micro-source inverter, a large amount of reactive power compensation is required to achieve voltage balance. If the inverter capacity is not considered at this time, the inverter will Overload, more serious and even cause reactive power oscillation

When the frequency and voltage amplitude of the large power grid fluctuate, it will also cause fluctuations in the output power of the micro-source inverter

Therefore, if you still rely on the traditional VSG control, it will not be able to meet the requirements of stable operation

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