Three-phase LCL type SAPF parameter design method based on double-loop current control strategy

Abstract

The invention discloses a three-phase LCL type SAPF parameter design method based on a double-loop current control strategy. The method comprises the steps of firstly building an equivalent admittance model of the interaction of an SAPF control system and a power grid based on a passivity theory under a double-loop current control framework, and defining two conditions which need to be satisfied for guaranteeing the stability of an interconnection system, and then, starting from the two stable conditions, designing LCL filter parameters and current controller parameters by using tools such as a Routh criterion, a Nyquist stability criterion, a root locus, a Bode diagram and the like. The parameters designed according to the method provided by the invention can enable the system to be stable, are not influenced by the impedance change of the power grid, are strong in robustness, and greatly widen the application scene of the SAPF.

Description

technical field [0001] The invention belongs to the technical field of power grid inverters, and in particular relates to a parameter design method for a three-phase LCL parallel active power filter (SAPF) based on a double-loop current control strategy. Background technique [0002] With the development of the power energy industry, more and more renewable energy power generation systems, power electronic devices and energy storage equipment are connected to the power system, which makes the characteristics of the power grid more complex and the problem of harmonic pollution is becoming more and more serious. As a typical power quality control device, the active power filter has the advantages of flexibility, high harmonic compensation accuracy, and rapid response, which can effectively alleviate the harmonic pollution of the power grid. [0003] In order to suppress the switching harmonics of the inverter, it is usually necessary to configure an L-type or LCL-type filter a...

AI Technical Summary

Problems solved by technology

[0005]The dual-loop current control structure includes the fundamental current loop and the grid current loop. The proportional resonant controllers in these two closed loops jointly affect the stability of the entire system. Any one Improper selection of controller parameters will cause system instability and collapse

However, the traditional controller parameter design method of "inner loop first, then outer loop" is not applicable in some scenarios, such as when the natural resonant frequency fres>fs of the LCL filter When sub> / 6, the inner loop of the system itself is unstable, and the outer loop, that is, the controller of the grid current loop, is needed to stabilize the system

In addition, in practical applications, SAPF often adopts digital control, which will introduce delay in the system loop, which will deteriorate the stability margin of the system, affect the active damping characteristics of the system, and change its robustness to grid impedance. Rod

Images