| Valve-regulated lead-acid battery(VRLA)is the core of energy supply in the emergency power supply system(EPS).When the city power is interrupted,EPS maintains the emergency power supply of important power facilities through the energy storage of the VRLA battery.In actual use,the maintenance of lead-acid batteries mainly relies on manual periodic inspections.However,due to the long inspection cycle and the adverse conditions such as overcharging and overdischarging,the batteries often fail to reach the expected use.In EPS,the storage battery exists in the form of a battery pack,and the deterioration of a single battery will lead to the inability of the entire battery pack to operate stably,and in serious cases,it may even cause an accident.Therefore,online monitoring of the operating state of the battery during use can achieve the purpose of timely understanding of abnormal conditions and timely replacement of deteriorated batteries,thereby ensuring the stable operation of EPS.In view of the above problems,this paper takes VRLA batteries as the research object,and after analyzing the existing battery testing instruments on the market,a set of online monitoring system for VRLA batteries is designed.The specific work content of this article is as follows:(1)By analyzing the working principle of the storage battery,important parameters that affect the characteristics of the battery are extracted.By analyzing the main characteristics of the battery,the monitoring target of the online monitoring system is determined,and the monitoring plan is designed.(2)By analyzing the existing battery model,the second-order RC loop model was chosen to model the battery.The calculation method of each parameter in the battery model is obtained through theoretical analysis,and the battery discharge experimental data is used to calculate the value of each parameter in the battery model.(3)Based on the parameter identification results of the second-order RC loop model,an unscented Kalman filter algorithm is used to establish the battery state output equation and observation equation,and the improved ampere-hour integration method is used to correct the predicted value of the battery state of charge(SOC).Finally,using the experimental discharge current as input,the SOC is verified by MATLAB simulation,and the result proves that this improved SOC estimation method has higher estimation accuracy.(4)Designed an online monitoring system.The system is divided into three parts:sensor,data concentrator and host computer.Through independent design of hardware circuits and software programs,online monitoring of battery terminal voltage,internal resistance,temperature and other parameters is achieved;meanwhile,a data concentrator module is designed to upload data to the host computer’s database through wireless communication Save it.Finally,this paper tests the accuracy of the monitoring parameters in the system,and compares the reference instruments to verify the monitoring accuracy of the system.In summary,this paper has designed a set of VRLA battery online monitoring system,which can effectively monitor the terminal voltage,internal resistance,temperature and SOC parameters of the battery,and can save the measured data to the upper computer side for Query and analysis.The research results have certain reference value for the design of lead-acid battery monitoring devices. |
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