Impedance calculation method of double-fed fan rectifier based on double closed loop control

Abstract

The invention discloses an impedance calculation method of a double-fed fan rectifier based on double closed loop control, comprising establishing a relationship expression between electrical quantityand control quantity according to circuit topology and control block diagram, deriving an expression of the closed-loop impedance and verifying the expression of the closed-loop impedance. Establisha relational expression between the electrical quantity according to the circuit topology, comprising a duty ratio signal, a direct current side voltage, a grid-side voltage and a grid-side current, establish a mathematical model of current inner loop control and voltage outer loop control parts according to the control block diagram, then establish a mathematical model of phase-locked loop part according to relationship between the circuit and the control, and jointly derive an expression of the closed-loop impedance expression; finally, verify the correctness of the impedance calculation method by inputting the disturbance at different frequencies and calculating the impedance value. According to the impedance calculation method of the double-fed fan rectifier based on double closed loopcontrol, a foundation for the stability study of the double-fed fan rectifier is laid, and parameters can be adjusted by impedance analysis to avoid phenomena that harm the power system such as harmonic instability and the like.

Description

technical field [0001] The invention relates to the technical field of stability analysis of a double-fed fan grid-side rectifier, in particular to a method for calculating the impedance of a double-fed fan rectifier based on double closed-loop control. Background technique [0002] As a clean and environmentally friendly green energy, wind energy has received more and more attention in recent years. Doubly-fed induction wind turbine has become one of the mainstream models in the field of wind power generation due to its good grid-connected stability and the advantages of decoupling control of active power and reactive power. However, as a power electronic component, the rectifier has some inherent defects in its structure, which may seriously affect the power quality and stability of the system. Among them, there are phenomena such as harmonic instability, which will not only deteriorate the supply environment of the grid system , causing the control system to be disordere...

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Problems solved by technology

Since the rectifier uses switching devices to introduce nonlinear characteristics, the establishment of the impedance model of the double-fed fan rectifier has also become a major difficulty.

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