Research On The Effect Of Voltage Caused By Grid-Connected Photovoltaic Power

Solar energy,a kind of clean,environmental and renewable resources,is abundant in nature.The effective utilization of solar energy resources is of great significance.Nowadays,the technology of photovoltaic power is more mature,and alleviate the pressure of environment and energy effectively.Large-scale distributed photovoltaic systems connected to power grid is the trend,and embodies the huge advantage of photovoltaic generation.The output of photovoltaic with light intensity and temperature is closely linked,The fluctuation of light and temperature makes the output of PV not stable.Photovoltaic connected to the power grid,makes a threat to the stability of distribution network.Photovoltaic system includes a lot of power electronic devices.It will inject into power grid harmonic and influence the power quality.Photovoltaic can change the structure of distribution network and influence distribution network planning.It can also change the intensity of power grid and cause short circuit current change,impact protection device to work properly.Among them,The impact on voltage is most serious.After photovoltaic connected to the distribution network,the node voltage of bus will be changed,continue to fluctuate and affect the user's normal power.Studying the effect of photovoltaic on voltage connected to distribution network,can help to master the relation of photovoltaic access number and location with the effect of voltage,and provide some references for the configuration of the position and capacity.Therefore,to study the effect on voltage of photovoltaic connected to distribution network has important significance.In this paper,the impact on the voltage of photovoltaic connected to the distribution network is researched in-depth.According to the working principle of photovoltaic cells,paper sets up simulation model and makes P-U and I-U simulation curves under different light and temperatures.The impact of node voltage is studied with access to the location and output of photovoltaic.Because the output and position is different,the voltage distribution is different.Finally,the paper choose four kind of load model and make simulation.This paper calculates voltage distribution,when containing a single photovoltaic with the feeder's node voltage formula and analysis the case of a single photovoltaic in-depth.According to the access capacity and access location of photovoltaic,this paper summarizes the law when containing a single photovoltaic and makes simulation model to verify the correctness of the rule.By detailed calculation,voltage distribution formula is deduced when two photovoltaics accessed based on the superposition principle and sums up the law of voltage distribution.To analyze voltage distribution when numbers of photovoltaics accessed,this paper proposes an algorithmabout voltage distribution.The algorithm expands the range of variable in formula and fitting to a continuous and derivable function except the access points.By derivation,the changes of voltage and voltage profile can be calculated by superposition principle.The algorithm can be used to calculate the best access points and capacity to solve the problem of voltage exceeding limits.This paper sets up the model of IEEE 33 nodes with Digsilent simulation software and connect photovoltaic to the model to simulate.The simulation verify the algorithm of voltage distribution.