Extended active power-based sliding mode variable structure direct power control (DPC) method for DFIG in unbalanced power grid

Abstract

The invention discloses an extended active power-based sliding mode variable structure direct power control (DPC) method for a DFIG in an unbalanced power grid. Extended active power is provided on the basis of a mathematical model of the DFIG in the unbalanced power grid, the extended active power and conventional reactive power are taken as control objects, a sliding mode variable structure algorithm and a DPC technology are combined, and an improved extended active power-based sliding mode variable structure DPC strategy is further provided. According to the method, the DFIG in the unbalanced power grid can be effectively controlled to obtain stable electromagnetic torque and reactive power as well as sinusoidal stator current on the premise of no positive and negative sequence separation of the voltage and current of the power grid; control can be systematically implemented simply without monitoring the frequency of the voltage of the power grid in real time by a phase-locked loop.

Description

technical field [0001] The invention belongs to the technical field of motor control, and in particular relates to a DFIG-based sliding mode variable structure direct power control method based on expanded active power under an unbalanced power grid. Background technique [0002] Modern wind power generation systems mainly adopt two types of doubly-fed induction generators and permanent magnet synchronous generators. In order to improve power generation efficiency, both adopt variable-speed and constant-frequency power generation operation modes. Among them, the doubly-fed induction generator (DFIG) has the most applications and the most mature technology, and is the current mainstream model. DFIG system structure such as figure 1 As shown, DFIG can realize variable speed and constant frequency control, reduce the capacity of the converter, and realize decoupling control of active power and reactive power. The flexibility of this power control is very beneficial to the powe...

AI Technical Summary

Problems solved by technology

However, in this control strategy, the calculation of the current reference value still needs to utilize the negative sequence component of the current

From the above analysis, it can be seen that the research on the improved control strategy of DFIG under the unbalanced power grid is based on the separation of the positive and negative sequences of the grid voltage and current, which will not only increase the complexity of the system, but also have a greater impact on the accuracy of the separation process. big dependence

Images