Low-voltage ride-through oscillation suppression method of VSC grid-connected power generation system applicable to weak network

Abstract

The invention discloses a low-voltage ride-through oscillation suppression method of a VSC grid-connected power generation system applicable to a weak network. An acquired grid-connected point voltageis used as an input signal of a phase-locked ring when oscillation is occurred during low-voltage ride-through process of the VSC grid-connected power generation system so that the frequency information of the grid-connected point voltage is obtained, the frequency is compared with a power frequency of a power grid to obtain instantaneous frequency deviation quantity, the frequency deviation quantity is input to an additional damping controller, an output of the additional damping controller is superposed into an active current control link of a network-side converter, and the oscillation ofthe grid-connected power generation system during the low-voltage ride-through process can be prevented. The additional damping controller is introduced into the active current control ink of the grid-connected converter, the small-interference oscillation mode-state damping of the VSC grid-connected power generation system during the low-voltage ride-through process is effectively improved underthe weak network, the small-interference oscillation suppression of the system is achieved, and the small-interference stability of the system during the low-voltage ride-through process is remarkablyimproved.

Description

technical field [0001] The invention relates to the suppression of small disturbance oscillations existing in the low voltage ride through (LVRT) process of a power generation system connected to the grid via a voltage source converter (VSC) under the condition of a weakly connected grid The method belongs to the technical field of new energy power generation. Background technique [0002] In order to solve the increasingly serious energy crisis and environmental pollution problems, vigorously promoting the development of clean, safe and renewable new energy technologies has become the only way for countries around the world to achieve sustainable development. Among them, most of the new energy power generation systems represented by wind power and photovoltaic power generation are connected to the grid through back-to-back dual PWM voltage source converters. As the installed capacity of these renewable energy sources increases gradually, the system short circuit ratio at th...

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Problems solved by technology

[0007] Literature (1)-(2) studied the small disturbance stability of the weakly connected permanent magnet direct drive wind power system and DFIG wind power system during the low voltage ride through process, and used the complex torque analysis method to explain the stability of the DFIG wind power system mainly depends on Due to the interaction between the phase-locked loop and the rotor current inner loop control, the stability of the permanent magnet direct drive wind power system is mainly affected by the phase-locked loop and the dynamic interaction between the phase-locked loop and the grid-side current control, and the bandwidth of the phase-locked loop, The bandwidth of the current inner loop, the stable operating point, etc. affect the stability of small disturbances, but no effective strategy for improving the stability of small disturbances in the low-voltage ride-through process has been proposed.

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