Control method of wind power generation double-feed converter space vector pulse width modulation (SVPWM) based on variable switching frequency

Abstract

The invention discloses a control method of a wind power generation double-feed converter space vector pulse width modulation (SVPWM) based on a variable switching frequency. The control method comprises the steps of: sampling three-phase current at the side of a motor rotor when a double-feed motor is normally combined to a grid to generate power; converting a voltage value of a three-phase static coordinate system into a two-phase synchronous rotation coordinate system; sampling the rotating speed of the motor rotor by a photoelectric encoder; obtaining torque at corresponding rotating speed according to a wind power curve; calculating out a q-axis current component of the side; taking the obtained current value under the two-phase synchronous rotation coordinate system as a feedback value, and the q-axis current component of the converter as a given value, and obtaining the current given value by calculation, inputting the values into a proportion integration differentiation (PID) link given by the current at the side of the converter; calculating out a given current value, and obtaining Ualpha and Ubeta under a two-phase static coordinate system; simultaneously, calculating out the frequency of SVPWM according to the given and feedback values of the q-axis current of the converter; and obtaining on / off of an upper pipe and a lower pipe of a three-phase bridge circuit according to different values of a switch function of a three-phase bridge arm of the side converter.

Description

technical field [0001] The invention relates to wind power generator drive technology, in particular to a control strategy of a variable switching frequency wind power double-fed converter SVPWM, which belongs to the field of power electronics and electric drive. Background technique [0002] In the application of doubly-fed wind power converters, the grid-side and machine-side dual SVPWM control technology is generally used. The double SVPWM converter has good input and output characteristics, and the power can flow in both directions, so that both the grid side and the machine side can absorb or emit energy; use the voltage vector orientation to calculate the decomposed d and q axis components, so as to control them separately . Among them, in the previous SVPWM modulation, the switching frequency is a fixed constant. In the case of high wind speed, the power fed into the power grid by the doubly-fed wind turbine is relatively high, and the current is large. At this time,...

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Problems solved by technology

Among them, in the previous SVPWM modulation, the switching frequency is a fixed constant. In the case of high wind speed, the power fed into the power grid by the doubly-fed wind turbine is relatively high, and the current is large. At this time, the relatively high switching frequency will make The temperature rise of the switching device is too high; and in the case of low wind speed, the power input to the power grid of the doubly-fed motor is relatively small. At this time, the relatively high switching frequency increases the loss of the switching device and affects the efficiency of the system.

Therefore, it can be concluded that the SVPWM control strategy with fixed switching frequency is not a good solution in wind farms with large wind speed changes.

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