Research On Power Quality Control Of Distributed Photovoltaic Power Distribution Network

After the introduction of distributed power generation into the distribution system,the power quality level directly affects the daily life and economic activities of users.Various power quality problems such as voltage deviation,harmonics,flicker,and three-phase imbalance.This paper studies two aspects of voltage deviation and harmonics,which have serious effects on the power grid.These problems have already posed a threat to the user's electricity safety and the economic operation of the distribution network,which has adversely affected the photovoltaic distribution network.Therefore,the power quality management of the distribution network is very necessary.In the distribution network under the condition of high penetration of distributed generation,how to establish a distribution network with high power quality and energy saving level is still an urgent problem to be solved.The main research contents of this article are as follows:First,analyze the characteristics of photovoltaic cells,establish an equivalent model of photovoltaic cells and photovoltaic power generation grid connection,and propose that the key factors that affect the nonlinearity of photovoltaic power generation output are temperature and light intensity;based on this article,after the distribution network is connected to photovoltaic The analysis of the change of power quality in China has provided an important theoretical basis for subsequent research.Secondly,this paper analyzes the traditional LCL passive filter and the APF active filter for the problem of harmonics,clarifies their advantages and disadvantages,connects the two in series to form an APF-LCL hybrid active filter,and then connects the grid and uses it Reversely compensate the harmonic current to suppress the harmonic.In the grid-connected inverter control,this paper adopts double closed-loop PI control and composite control strategy,and uses MATLAB/Simulink to build a system simulation model for simulation verification.The results show that the content of harmonics in the distributed photovoltaic distribution network with distribution is significantly reduced,and the output voltage and The quality of the current waveform can meet the requirements of network access,and the power quality of the distributed photovoltaic distribution network has been significantly improved.Finally,for the problem of harmonics and low voltage,this paper proposes a control strategy based on expert decision to coordinate and operate APF-LCL,STATCOM and photovoltaic,thereby greatly saving the investment required for reactive power compensation and reducing harmonics The content makes the voltage and current output stable to meet the photovoltaic grid connection requirements.The simulation model is established by software to verify the integrated control strategy.The results show that this strategy can effectively suppress the system power oscillation under the premise of ensuring the stable operation of the system,thereby ensuring the stability of the system voltage and promoting the improvement of the system power quality.