Research On Energy Conservation And Emission Reduction Of Communication Base Stations

Due to the large number of communication base stations,communication companies need to spend a lot of power costs and equipment maintenance costs each year.In order to promote the sustainable development and respond to the national policy of energy saving and emission reduction,communication companies further reduce the power consumption and pollution emissions of communication base stations by vigorously increasing the proportion of new energy such as wind power and new types of storage batteries.Air conditioner is the main energy-cnsuming device of the base station.The outdoor cold air by natural ventilation can cool down the temperature in the base station,which results in greatly reducing the operating time of the air conditioner and the power costs for the company.However,real natural ventilation field experiments usually cost a lot and the cycle of repeated experiments is long.As a new type of storage battery applied in the source system,the lithium-ion battery has an excellent high-temperature performance compared with lead-acid battery,which can further increase the starting temperature of air conditioners and thus reduce the working time of air conditioners.Lithium-ion batteries have no harmful substances,which can reduce pollution emissions when recycling.Therefore,lithium-ion batteries are gradually used in engineering applications.However,the power failure and supply instability of base station are serious in remote areas or areas where the base station is modified frequently,which will result in the battery charging and discharging frequently.Over charging or over discharge will usually reduce the actual useful life and available capacity of the battery,accelerate the battery degradation and reduce the energy efficiency.In order to make full use of the service life of the battery and increase the efficiency of battery energy use,it is usually necessary to predict the actual remaining useful life(RUL)of the battery.However,the base station batteries are usually replaced by human experience or regular inspections.This rough management often causes the battery to retire prematurely and wastes battery resources.This thesis has done research on the methods of the efficient use of the natural ventilation and lithium-ion battery for the energy conservation and emission reduction of communication base stations.The main contents and innovations of this thesis are as follows:1)In order to reduce the experimental cost at the initial stage of design,shorten the research time and improve the natural ventilation,this thesis uses numerical simulation technology to establish a simulation model of natural ventilation cooling of base station based on chimney effect,and verifies it by model experiment.Firstly,this thesis analyzes the cooling effect of the chimney effect in the base station environment theoretically.Secondly,based on the theory of the computational fluid dynamics(CFD)and numerical simulation techniques,a simulation model for the base station is established.Finally,similarity theory is utilized to establish the similarity relationship between the prototype and the model,and the appropriate similar scale is used to establish the model experiment.The experimental results verify that,with a variety of operating conditions,the simulation results of the reduced size model of the communication base station are consistent with the results of model experiment,which verifies the correctness of the natural ventilation cooling simulation model of the base station.The results of prototype-size simulation model are consistent with the reduced-size simulation model,which verifies the rationality of the parameter design of model experiment.This research can provide a convenient,reliable and economical solution for the initial guidance design of communication base stations.2)Over charging or over discharge will usually reduce the available capacity of the battery,accelerate the battery degradation and reduce the energy efficiency.Therefore,it needs to monitor the state of the battery.Since the remaining capacity of the lithium-ion battery cannot be monitored directly by the sensor,the remaining capacity estimation is studied in this thesis.The parameter values of the battery characteristic will gradually drift when the battery is working.Based on the dual Kalman filter framework,this thesis proposes a novel method called dual square root cubature Kalman filter(DSRCKF)to realize the estimation of the battery remaining capacity while the battery parameters can be updated in real time.The proposed method in this thesis are compared with dual extended Kalman filter(DEKF)and dual square root unscented Kalman filter(DSRUKF)methods.The results of experiment show that the DSRCKF method has the excellent balance ability among them in the fields of the estimation accuracy,execution time,and convergence rate.3)In order to make full use of the service life of the battery,overcome the shortcoming of the rough battery management and increase the efficiency of battery energy use,this thesis proposes an on-line prediction method of lithium-ion battery RUL.Firstly,by analyzing the trend of battery discharge voltage in the battery degradation process,we propose to reconstruct the original health indicator by using permutation entropy(PE),and utilize the PE to quantify the degradation performance of lithium-ion battery.Secondly,the PE value of the discharge voltage during each cycle is extracted,and the PE sequence with the battery degradation process is constructed.Finally,considering the ARIMA model is essentially a linear model,and the battery degradation is a nonlinear process,it has a nonlinear error.In order to reduce the nonlinear error,this thesis proposes a hybrid model,which consists of the variational mode decomposition(VMD)denoising technology,ARIMA model and GM(1,1)model,to predict the lithium-ion batteries RUL.The experimental results show that(a)PE is basically linear with the maximum available capacity of the battery,indicating that the battery degradation process can be well expressed by PE;(b)The longer the length of the discharge voltage sequence at the self-recharge stage,the larger the PE value and the stronger ability to express the battery degradation;(c)Compared with the MVF and DVD ETI,PE has the best expression ability for the lithium-ion battery degradation behavior;(d)Compared with EMD_ARIMA prediction method,the hybrid model prediction method presented in this thesis has more satisfactory prediction accuracy and execution time in estimating the RUL of lithium-ion battery.