Electrical Breakdown Properties and Space Charge Formation in High Temperature Region in Ultraviolet Ray Irradiated PVC

Polyvinyl chloride (PVC) is the most popular insulating material for electric wiring instruments. However, an exothermic reaction above 150 °C may cause deterioration of the insulating properties of PVC. Therefore, it is important to clarify the heat degradation in PVC, not only to investigate the ignition of electrical wiring products but also to use electrical products safely. It is known that ultraviolet (UV) irradiation causes chemical deterioration of PVC and an increase in its conductivity. Generally, it has been thought that the electrical breakdown properties, electrical conduction, and insulating performance are affected by space charge accumulation in an insulating material. A high temperature pulsed electroacoustic (PEA) system usable up to 250 °C has been developed, and the PEA system can measure the space charge distribution and conduction current in the high temperature range simultaneously. In this investigation, the space charge distribution and conduction current were measured up to electrical breakdown in a non‐UV irradiated sample (normal PVC) and in 353 nm and 253 nm UV‐irradiated PVC samples in the range from room temperature to 200 °C in a DC electric field. In the short wavelength UV irradiated PVC sample (253 nm, 300 h), a deterioration of breakdown strength at 90 °C to 150 °C and negative packet‐like charges were observed at 60 °C and 100 °C, a positive charge accumulated in front of both the anode and cathode above 90 °C, and a higher electric field near the cathode side because the positive charge of the cathode side was greater.     

不同正极活性物质的钛酸锂负极锂离子电池

采用4种正极活性物质,设计32650型4.0 Ah钛酸锂(Li_4Ti_5O_(12))负极锂离子电池,评估充放电倍率性能、放电温升、低温放电性能、循环性能和安全性能。尖晶石镍锰酸锂(Li Ni0.5Mn1.5O4)正极电池的电压平台高(3.15 V),-20℃下的1 C放电(3.3~2.0 V)容量是常温时的83.16%,比能量为74.57 Wh/kg;磷酸铁锂(LiFePO_4)正极电池的电压平稳(1.70 V),适用于对电压要求严格的领域。三元材料正极电池中,镍钴锰酸锂(LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2)正极电池的各项性能较优,3 C循环3 486次的容量保持率为102.58%,可用于快充领域;镍钴铝酸锂(LiNi_(0.8)Co_(0.15)Al_(0.05)O_2)正极电池更适合于储能领域。     

A novel quasi-oppositional harmony search algorithm and fuzzy logic controller for frequency stabilization of an isolated hybrid power system

The intermittent wind power in isolated hybrid distributed generation (IHDG) may cause serious problems associated with frequency (f) and power (P) fluctuation. Energy storage devices such as battery, super capacitor, and superconducting magnetic energy storage (SMES) may be used to reduce these fluctuations associated with f and P. This paper presents a study of IHDG power system for improving both f and P deviation profiles with the help of SMES. The studied IHDG power system is consisted of wind turbine generator and diesel engine generator. Both f and P control problems of the studied power system model are addressed in presence or absence of SMES. Fuzzy logic based proportional–integral–derivative (PID) controller with SMES is used for the purpose of minimization of f and P deviations. The different tunable parameters of the PID controller and those of the SMES are tuned by a novel quasi-oppositional harmony search algorithm. Performance study of the IHDG power system model is carried out under different perturbation conditions. The results demonstrate minimum f and P deviations may be achieved by using the proposed fuzzy logic based PID controller along with SMES.     

具备故障定位功能防反充电PT并列装置的研制

为杜绝电压互感器(PT)并列反充电导致并列装置损坏、空开跳闸等故障发生,研制出一种基于ARM的具备故障定位功能防反充电PT并列装置。详细介绍了该装置工作原理及总体构成、软硬件设计。该装置通过采集、计算同相电压差值作为并列必要条件,具有传统PT并列装置没有的防异常并列、防反充电功能。且并列电路中设计有由新型电子元件自恢复保险丝(PPTC)构成的过流阻断电路,可瞬时隔离故障并能自动恢复。通过电压比较、判别,能自动定位、识别高压保险熔断、二次空开跳闸、母线接地等故障,并实时显示各相电压值及故障信息,大大缩短检修人员故障查找处理时间,提高了供电可靠性。     

基于深度学习的锂离子电池SOC和SOH联合估算

锂离子电池常被作为储能元件以实现电能的存储和转化,然而其荷电状态(state of charge,SOC)和健康状态(state of health,SOH)无法被直接测量。为了实现锂离子电池SOC和SOH联合估算,该文分析SOC和SOH之间的关联性,并提出一种基于深度学习的锂离子电池SOC和SOH联合估算方法。该方法能够基于门控循环单元循环神经网络(recurrent neural network with gated recurrent unit,GRU-RNN)和卷积神经网络(convolutional neural network,CNN),利用锂离子电池电压、电流、温度,实现锂离子电池全使用周期内SOC和SOH的同时估算,而且由于将锂离子电池的SOH估算值考虑到SOC估算中,能够消除锂离子电池老化因素对锂离子电池SOC估算造成的负面影响,从而提升SOC估算精度。两个锂离子电池测试数据集上的实验结果表明,提出的估算方法能够在不同温度和不同工况下实现锂离子电池全使用周期SOC和SOH联合估算,且获得较高的精度。     

基于Stacking模型融合的专变用户电费回收风险识别方法

针对当前电力公司面临的专变用户电费回收风险,提出一种基于Stacking模型融合的专变用户电费回收风险识别方法。对专变用户数据进行特征处理、特征构造与特征筛选,从样本分布和特征属性上优化模型的泛化性能;利用Stacking模型融合多个基学习器,构建专变用户电费回收风险识别模型。实验结果表明,相较于其他常用的分类算法,所提方法具有更优的精确率、召回率、P-R调和均值、AUC值以及模型泛化性能,对专变风险用户的识别率也更高。     

基于扩张状态观测器的PMSM积分时变滑模控制

为了实现永磁同步电机(PMSM)驱动系统的高精度跟踪控制,提出了新型积分时变滑模控制策略,该策略考虑到系统的非线性和耦合特性对动、静态性能的影响,首先采用反馈线性化原理将系统模型线性化,然后为了加快动态响应过程,采用单回路结构取代串级结构设计积分时变滑模控制器。针对负载扰动的问题,设计了一种以负载转矩为观测对象的扩张状态观测器,并将观测值反馈到控制器中以克服扰动对性能的影响。最后在永磁同步电机实验平台上开展了对比实验研究,通过实验结果可以看出,积分时变滑模控制器使系统具有无超调、快速性的优点,提高了系统的动态和稳态性能,扩张状态观测器能够快速跟踪负载的变化,增强了控制器对负载扰动的鲁棒性。     

退役动力电池一致性评估及均衡策略研究

电池梯次利用是处理动力电池庞大退役量的有效手段之一.针对退役电池梯次利用过程中分选技术进行研究,主要从退役电池SOC关键参数分布特性以及退役电池一致性控制策略分析两方面展开.提出主动被动协同均衡策略考虑电池参数的相关性,弥补了单一均衡方式的不足.同时提高充放电均衡控制的可靠性,实现了均衡效率的最优化.分析退役动力电池荷...     

考虑先导发展随机性的输电线路雷击仿真模型

随着电压等级的升高,由雷电绕击而引起的线路跳闸事故所占比例越来越大。为准确评价线路的绕击耐雷性能,考虑先导发展随机性,运用模拟电荷法,建立了输电线路雷屏蔽性能的雷击仿真模型。仿真结果表明:随着下行先导随机发展的方向由靠近输电线路变为远离输电线路,雷击目的物也由地线逐渐转变为导线,并最终变为大地;相比地线,导线上的上行先导较难产生。算得的对地击距与IEEE推荐的击距公式一致,绕击概率与雷击模拟实验结果相符,证实了模型的可信性。     

注入式混合有源滤波器的三重滑模变结构控制

有源滤波器(Active Power Filter,简称APF)电流跟踪控制方法的优劣直接影响其谐波治理效果.首先建立了一种新型注入式混合有源滤波器(Hybrid Active Power Filter,简称HAPF)的数学模型,同时针对控制参考信号为周期量这一特征,结合传统滑模变结构控制算法快速性好和递推积分PI控制算法无稳态误差的优点,引入递推积分PI控制算法的控制量作为离散滑模变结构控制器的等效控制,提出了一种三重滑模变结构控制算法.通过仿真,从算法的跟踪速度和控制精度方面,将三重滑模变结构控制算法与传统滑模变结构控制算法以及单一的递推积分PI控制算法进行了比较分析.实验结果证明了该算法的正确性和有效性.