A vector control method for direct drive wind power converter without stator voltage measurement

Abstract

A vector control method without stator voltage measurement for a direct-drive wind power converter, comprising five parts: a stator current calculation link, an initial flux linkage calculation link, a flux linkage phase-locked link, a reference current calculation link, and a current closed-loop control link. The stator current calculation link collects the three-phase stator current I sa , I sb , I sc , transformed into the stator current I on the αβ coordinate system sα , I sβ and the stator current I on DQ coordinates sd , I sq ; The initial flux linkage calculation link outputs 7 zero vectors of ΔT0 time, and determines the angular frequency ω of the generator at the moment of allowable starting in 8 stages 0 and the initial value of the flux angle θ ψ0 , the output machine-side converter is allowed to start the flag ST_Per; the flux linkage phase-locked link is at ω after ST_Per=1 0 , θ ψ0 On the basis of phase locking, the output generator angular frequency ω and flux linkage angle θ ψd ; The reference current calculation link outputs the stator reference current I on the DQ coordinate system sdRef , I sqRef ; The current closed-loop control link uses a PI regulator to perform closed-loop control on the stator current on the DQ coordinate system, and outputs the stator control voltage U on the αβ coordinate system sca , U scβ and the stator control voltage U on the DQ coordinate system scd , U scq .

Description

technical field [0001] The invention relates to a vector control method without stator voltage measurement for a direct drive wind power converter. Background technique [0002] In recent years, with the vigorous promotion and development of green energy, my country's wind power industry has developed rapidly, and its cumulative installed capacity and annual new installed capacity both rank first in the world. With the development of onshore low-wind-speed wind farms and the rapid development of offshore wind power, a consensus has been reached on the use of large-megawatt wind turbines for onshore and offshore wind power. The power level basically starts from 4MW, and direct drive based on permanent magnet synchronous generators is generally used. Technical route, the converter adopts a three-phase voltage AC-DC-AC bidirectional converter. Due to the influence of the industrial chain, most of the current high-power offshore direct-drive wind turbines still follow the 690V ...

AI Technical Summary

Problems solved by technology

The 690V low-voltage technical route generally adopts the resistor divider non-isolation scheme, and the potential safety hazards of this scheme gradually become prominent when the voltage level is getting higher and higher.

[0004] Patent 201510755713.3 "A three-phase converter model predictive control method without voltage sensor", discloses a model predictive control method of converter without voltage sensor based on quadratic programming algorithm optimization, which can reduce the amount of calculation , reduce the difficulty of parameter setting, but the control object is only the grid with fixed frequency, and the initial value of the flux linkage of the control method is not considered; , He Yikang, etc.) proposed a three-phase PWM rectifier vector control technology based on grid virtual flux linkage without grid voltage sensor. Before the control method runs, the initial value of virtual flux linkage in the control method is obtained by outputting zero vectors of several PWM cycles. , only applicable to grids with fixed frequency, and when applied to large megawatt offshore direct-drive wind power converters, continuously outputting zero vectors of several PWM cycles will cause serious overcurrent problems

Images