Research On Low Voltage Ride Through Control Strategy Of Photovoltaic Inverter

According to the technical requirements of national economic development,integrating large scale new energy(wind power,photovoltaic,and battery energy storage systems)into power system is a new topic accompanying with little engineering experiences worldwide.And these plants give new challenge to planning,operating,and analyzing of power system.With the photovoltaic installed capacity increasing and the power generation cost decreasing,the photovoltaic dynamic behavior has been receiving more attention during and after the disturbance stresses.To protect the power grid,the photovoltaic farm usually cuts the motor during voltage depressions.Despite the solution makes it,it will heaven the grid condition once facing the perturbation.Obviously,the tradition solution isn’t suitable for the technical demands for large-scale solar plant.So it is necessary to realize the low Voltage ride through capacilty.That is to say,faced with the low voltage,the photovoltaic generations keep running until the power grid gets well.In large interconnnected power grids,LVRT does make contributions to maintain the security and reliability of the grid.So the model of the photovoltaic generation system including LVRT capacility is built based on the GE articles in this paper.In this subject,the studies are researched as follows:(1)Firstly,building the photovoltaic generation system model based on GE is needed.The model contains four sub-models:the solar plant model,the active control model,the reactive control model and the converter model.LVPL,LVACMF and HVRCMF are included in the converter model.(2)Then I make more elaborations about the low voltage power logic.The LVPL reduces system stress during and immediately following sustained faults by limiting the real current command with both a cap and a ramp rate limit.it is the solar plant becoming more large-scale that accelerates the power grid’s steps to make the technical requirements.This paper also introduces the demands for next comparations.(3)Subsequently,This paper uses the FASTEST software to prove the solar plant LVRT capacity having been realized based on the Ningxia’s power grid datas.Comparing the simulation results with the technical requirements in three parts:the fundamental demands,the active power recovery,the dynamic reactive power support.(4)In the end,this paper concludes the work that I do during the studies and makes some expectaions for further studies.