Research On Voltage Menegement For Low Voltage Distribution Network

With the accelerated development of the global economy,energy shortage and environmental pollution has become a serious problem.This problem also promotes the research and development of renewable energy.Photovoltaic power generation occupies a very important position in many renewable energy resources.As the increasing numbers and capacity of photovoltaic generator in distribution network,the voltage rise problem will occur which would not only threaten the stability of the grid,but also hinder the improvement of renewable power.Intermittent and random distributed generators will cause voltage fluctuations,and the closer to the terminal nodes of feeders,the more serious phenomenon it is.This paper mainly analyzes the mechanism of the main structure of low-voltage distribution network and the voltage fluctuation phenomenon.It is found that the main reason for the terminal voltage lifting is due to the limited capacity of load reduction.When the output power of the distributed power exceeds the power distribution capacity of the distribution network,the output power will send reverse power flow to the main network.Because of the existence of the line loss,the voltage will be raised.In this paper,the IEEE 13 node distribution network is used to test control method,and the distribution network with high permeability and renewable energy is built according to the actual survey data.Meanwhile,the corresponding distribution network is built in the DIGSILENT simulation environment.Furthermore,the author studied the voltage menegement methods for the low voltage distribution network accessed with photovoltaic generators.In this paper,firstly,the characteristics of traditional V-Q voltage control strategy under different slope was compared,and the reactive power compensation was adopted by means of adjusting inverters,the voltage control ability under different parameter settings and its influence on power grid stability are also analyzed.Then this paper proposed an active and reactive power coordinated control(ARPCC)method to maintain the voltage stability while guarantee the efficiency of the photovoltaic inverter.By predicting the active power in the voltage limit,the active power exceeding the value is reduced and the voltage stability is maintained by reducing a certain amount of active power.This method is compared with traditional active power regulation.It is found that this method has higher utilization rate of renewable energy while maintaining voltage stability.In addition,this paper also proposed an OLTC(on load tap changer)-inverter regulation strategy based on fuzzy control and power allocation optimization(PAO),which coordinates the original isolated inverters and turn the voltage problem to an optimization view.The object of optimization is to maximum the total active power output of the DGs in the network system while the voltages condition are set as constratint.Thus,the V-Q curve slope of each inverter is adjusted to realize the coordinated output between the multiple inverters.While the voltage stability is guaranteed,the utilization efficiency of the whole renewable energy is also improved.