Current converter control method for improving low-voltage ride-through capability of doubly-fed fan

Abstract

A current converter control method for improving the low-voltage ride-through capability of a doubly-fed fan comprises the steps that after the voltage drops suddenly, the voltage of a direct-currentcapacitor and the current ir of a rotor are monitored constantly, and whether the voltage of the direct-current capacitor or the current of the rotor exceeds a limit value or not is judged; when the direct-current capacitor voltage or the rotor current ir exceeds a limit value, an active Crowbar protection circuit is triggered; when the direct current capacitor voltage and the rotor current are both lower than the limit value and no out-of-limit is kept in the two cycles, the active Crowbar protection circuit is exited, and PI control of the rotor side converter and the network side converterare switched into comprehensive interference suppression control at the same time; and after voltage drop is recovered, PI control is switched back, and the purpose of low-voltage ride through of thewind power plant under sudden power grid fault drop is achieved. Compared with a PI control strategy, the comprehensive LVRT control strategy designed by the invention can make full use of the outputcapability of the converter, has the better transient control performance in the voltage drop period, and can effectively meet the low-voltage ride-through requirement of the doubly-fed fan.

Description

technical field [0001] The invention belongs to the field of power system control, and relates to an independent nonlinear control method for double converters, in particular to a converter control method for improving the low-voltage ride-through capability of double-fed wind turbines, and is especially suitable for grid connection with large-scale wind power generation transmission system. Background technique [0002] The crisis of global fossil energy shortage and environmental pollution is gradually aggravating, and the development of renewable energy has attracted widespread attention. Among various types of wind generator systems (WGS), those based on doubly fed induction generators (DFIG) are widely used due to their small size, low cost, and flexible control. Onshore wind farms. [0003] Since the stator windings of DFIG are directly connected to the grid, the operation of the wind turbine is susceptible to grid disturbances, especially grid voltage dips. For thi...

AI Technical Summary

Problems solved by technology

However, these controllers do not fully consider the nonlinear characteristics of the grid-side converter model in practical applications, and cannot guarantee the ideal control performance

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