Research On The Control Technology Of Power Quality/Microgrid Integrated Experimental Platform

Modern industrial production and the development of information technology put forward higher requirements for power quality.According to the national standards of power quality,power electronic devices are used to achieve accurate and real-time simulation output of various power quality parameters,and the test results of equipment are further analyzed and processed,which can provide a basis for comprehensively and accurately understanding and solving the power quality problems of the current power grid.In order to meet the above requirements,this paper develops a power quality/microgrid integrated experimental platform.To meet the requirements of disturbance rejection,a voltage control strategy of LADRC with capacitive current feedback is proposed.To meet the control accuracy requirements,an external loop control strategy of FFT-LADRC is proposed.In addition,aiming at the power quality control of low-voltage microgrid,this paper proposes an adaptive harmonic droop control strategy for low-voltage microgrid inverters.Firstly,it is designed a three-level inverters construction scheme for the power quality/microgrid integrated experimental platform,the controller framework and hardware schematic diagram for the inverters on this paper.Then,the mathematical model of the inverters on the DQ axis is established.According to the mathematical model,the extended state observer and linear error feedback control rate are designed,and the LADRC voltage control algorithm with capacitive current feedback is constructed.Based on the steady state model of the above-mentioned LADRC control system,the FFT-LADRC control algorithm is designed.At the same time,the anti-disturbance performance and stability performance of the two algorithms are analyzed.In addition,this paper introduces the idea of fundamental robust droop control into harmonic control,establishes and analyses the control block diagram of robust harmonic droop control,simplifies the design of droop controller according to the particularity of rated harmonic control conditions,and designs the droop coefficient adaptive adjustment strategy and multi-quasi PR current tracking scheme on this basis.Then,the simulation software PSCAD and the power quality / microgrid integrated experimental platform are used to verify all the above algorithms.The experimental results show that the proposed LADRC voltage control strategy with capacitive current feedback has higher immunity to disturbance than the traditional PI double-loop control,and has no overshoot and no coupling.FFT-LADRC control strategy can make the inverter output the harmonic component without static error quickly,and the regulation process is also non-overshoot and uncoupled with a certain anti-disturbance ability.The adaptive harmonic sag control strategy of low-voltage micro-grid inverters can suppress the harmonic voltage of grid-connected points within a set range,and can distribute harmonic power according to the capacity of the inverters.This paper provides a set of precise experimental platform and control algorithm for power quality testing,and proposes an efficient harmonic control scheme,which has high economic benefits and engineering value.