光伏发电系统中影响蓄电池寿命因素分析

Analysis of factors influencing the lifetime of lead-acid battery in photovoltaic system

在光伏发电系统中 ,蓄电池寿命要比所预定的短。充电率小和酸分层导致蓄电池极板底部处于欠充状态 ,加剧了硫酸盐化。而小电流放电下所形成的PbSO4 结晶颗粒粗大 ,这种结晶溶解困难 ,影响了PbSO4 转化为PbO2 的效率 ,最终影响了蓄电池的寿命。深度放电后 ,蓄电池的容量恢复程度和充电方法有关。适量的过充有利于蓄电池的容量恢复。提出一种新的控制策略。根据该控制策略 ,蓄电池的充电过程分为两个阶段 :全充阶段和脉冲阶段。全充阶段的充电终止电压采用模糊逻辑算法而得 ;脉冲充电阶段控制电压根据对蓄电池的浮充电压修正而得 :两阶段的控制电压都将根据环境温度进行补偿。

The batterys lifetime in photovoltaic system is shorter than one might expect.The low charging rate in conjunction with acid stratification cause a significant undercharging of the low part of the electrodes,which again causes accelerated sulphation.The size of sulphate crystals increases with decreasing discharge current.The difficulty of dissolving these large sulphate crystals influences conversion efficiency from PbSO 4 to PbO 2,and ultimately affects the batterys lifetime.A new control stratagem is presented.According to this control stratagem,the charging cycle includes two phases:deep charging and pulse charging.In the period of deep charging,the end point charging voltage is calculated by fuzzy logical algorism.Pulse charging voltage is obtained through modifying batterys float voltage.These two control voltages are compensated by temperature.