Three-phase LCL type inverter control method and device based on harmonic interference observer

Abstract

The invention discloses a three-phase LCL type inverter control method and device based on a harmonic interference observer. The method comprises the following steps of establishing a mathematical model under a dq rotating coordinate; introducing capacitive current active feedback damping to obtain an equivalent controlled object mathematical model, and discretizing the model to obtain a z-domainmathematical model; on the basis of proportional negative feedback of a current inner loop and direct feedforward of a power grid voltage, designing a Q (z) filter of a discrete disturbance observer by adopting an infinite impulse response filter method, introducing a first-order low-pass filter and a zero-phase shift low-pass filter into a Gpn-1 (s) channel and an output channel of the disturbance observer to filter a high-frequency noise, and introducing two beats of advance into output of the disturbance observer to compensate time delay of digital control; subtracting an output observationvalue of the disturbance observer from the output of the current inner loop proportional negative feedback, and compensating disturbance so as to obtain a high-quality inverter output current. A problem of LCL inverter output current distortion caused by disturbance of a dead zone effect, power grid voltage distortion, parameter perturbation and the like is solved.

Description

technical field [0001] The invention belongs to the field of electrical technology, and more specifically relates to a control method and device for a three-phase LCL inverter based on a harmonic interference observer. Background technique [0002] The LCL inverter is a key device in the fields of distributed new energy generation and power quality management. The main goal of the design of its control system is to achieve zero static error tracking of the inverter output current, low harmonic content of the grid-connected current, and Fast dynamic response and strong robustness, etc. These goals are closely related to factors such as switch tube dead zone effect, grid voltage distortion, parameter perturbation, and control system delay. Therefore, it is necessary to overcome the influence of various unfavorable factors when designing the controller to ensure that the LCL inverter system has good steady-state and dynamic performance. [0003] In the actual inverter system, ...

AI Technical Summary

Problems solved by technology

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a three-phase LCL inverter control method and device based on a harmonic disturbance observer, aiming at solving disturbances such as dead zone effect, grid voltage distortion and parameter perturbation Problems that cause distortion of the output current of the LCL inverter

Images