Hybrid controller switching fault ride-through control method for MMC-HVDC

Abstract

The invention discloses a hybrid controller switching fault ride-through control method for an MMC-HVDC. The method comprises the steps of: constructing a hybrid controller of the MMC-HVDC, wherein a rectification side MMC employs DC voltage control and AC voltage control, an inversion side MMC employs active power and AC voltage control, and both of them employ inner and outer ring control structures; constructing an input variable value of each switching control unit, judging whether an absolute value of a deviation value of an object controlled by each switching control unit reaches a set switching condition or not, and switching to control based on a first-order logic switch controller or a vector controller; and outputting output control voltage and current reference values of each switching control unit based on the maximum positive current or voltage output and the minimum negative current or voltage output of the MMC output by the first-order logic switch controller and a steady-state value obtained when the system is balanced. According to the hybrid controller switching fault ride-through control method, the capability of maintaining stable operation of the MMC-HVDC after being subjected to large disturbance is enhanced.

Description

technical field [0001] The invention relates to the technical field of electric power automation control, in particular to an MMC-HVDC hybrid controller switching fault ride-through control method. Background technique [0002] Due to the high quality of the output waveform, the flexibility of expansion, and the ability to support the voltage and frequency of the AC grid, the MMC-HVDC transmission system is expected to perform stable operation against AC grid disturbances and help the AC grid recover from severe disturbances. Therefore, the fault ride-through capability of MMC has an important impact on the stability of the entire power system. The tuning of the traditional VC control system needs to comprehensively consider the rapidity of system response and steady-state error, and then determine a compromise control parameter. However, after the power system is greatly disturbed, the MMC-HVDC deviates from the original operating point, and the traditional vector control ...

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Problems solved by technology

However, after the power system is greatly disturbed, the MMC-HVDC deviates from the original operating point, and the traditional vector control system cannot exert the maximum control energy of the MMC converter to make the MMC-HVDC return to the original equilibrium point at the fastest speed. run

Therefore, when a major fault occurs with a small probability in the power system, the traditional vector control system cannot guarantee the stable operation of MMC-HVDC

The traditional switch control method uses the maximum value principle to obtain the control law by solving the Hamiltonian equation of the system. However, to establish a Hamiltonian function of a large-scale power system, it is necessary to know the parameters of the entire system and all state variables, and the The resulting Hamiltonian will be very complex

This poses a great challenge to solve its regular equation

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