锂离子电池储能电站热失控预警与防护研究进展

锂离子电池储能电站安全问题是制约能源变革与“双碳”长远目标实现的重要因素。一旦储能电站发生安全事故,造成的财产损失和人员伤亡将非常严重。文中分析了锂离子电池储能电站引发安全事故的原因;综述了储能电站发展至今安全前置的各类预警技术,介绍了抑制储能电站热失控扩散的灭火剂种类及优缺点;对近年来工程应用及实验研究安全预警和防护的技术特点进行了总结和讨论;最后,针对各类应用场景的锂离子电池储能电站,从行业健康、有序、长远发展的角度,指出在安全事故预警、防护方面存在的问题,并对未来发展技术趋势进行了展望。

基于PSO-CNN的储能锂离子电池组荷电状态评估

将卷积神经网络(convolutional neural network,CNN)的权值和阈值作为粒子群算法(particle swarm optimization,PSO)的粒子,将CNN的损失函数作为PSO的适应度函数,从而构建PSO-CNN算法对储能锂离子电池组的荷电状态(state of charge,SOC)进行预测。以储能系统现场采集的充放电数据为样本,分别采用本文算法、基于PSO优化的支持向量机(support vector machine,SVM)、CNN进行训练,并在完整充放电数据集上对比3种算法的预测效果。结果表明本文算法收敛性好、预测精度高。最后采用另一储能现场的数据验证本文算法具有良好的鲁棒性,可以广泛适用于储能系统锂离子电池组SOC的在线预测。

可靠性仿真在鱼雷产品上的应用

针对传统可靠性试验耗时长、成本高的问题,给出了可靠性仿真的基本内容和工作流程,针对鱼雷产品中的典型电子组件开展可靠性仿真建模、热应力和振动应力仿真分析、故障预计和可靠性评估,以得到产品设计薄弱环节、潜在故障信息和平均首发故障时间等。分析结果表明,可靠性仿真能够确保在鱼雷产品设计早期消除故障源,从而提高鱼雷产品的鲁棒性和故障预测能力。

锂离子电池容量衰减原理研究进展

电化学储能是构建新型电力系统,完成能源结构转型,实现“双碳”目标的关键技术支撑。其中,锂离子电池在电化学储能装机容量中占比九成,是核心的技术发展路线。锂离子电池在使用过程中,会遇到短路、内阻增大、漏液产气、析锂、热失控等造成循环性能下降、容量衰减现象,严重影响了电池的经济使用性和安全性。电池容量衰减主要包括不可逆容量衰减和可逆容量衰减,进一步分为静置中衰减和运行中衰减。综述了锂离子电池的容量衰减分为外部因素和内部因素两种类型:外部因素包括工作环境、放电深度、放电电流、使用工况;内部因素包括正极材料溶解、负极材料表面析锂、固体电解质膜(SEI)增厚破裂、电解液还原等。从电池内部电化学反应机理和外部工程实际应用场景,研究了锂离子电池容量衰减原理,并对其进行了总结和展望。

三元锂电池的过放电诱发内短路实验研究

设计了针对电池过放电特性的测试方法,并研究在不同的过放电程度下电池的内短路程度变化规律。结果表明:对于本实验所采用的三元锂电池,其过放电特性具有较好的一致性,其中SOC一致性比电压一致性更好;内短路的严重程度与过放电深度呈现非线性增长的关系。当本实验所采用三元锂电池过放电至-18%至-20%的SOC时,将发生不可逆的严重内短路现象,电池将表现成为一个线性电阻;而在发生严重内短路前,充电后的电池存在一个自修复的过程。

高倍率双层碳包覆硅基复合材料的制备研究

硅材料作为锂离子电池负极材料具有4200 mA·h/g的超高理论比容量,也因此成为了科研机构和高校的研究热点。但是硅基材料在脱嵌锂的过程中有着巨大的体积变化,膨胀收缩率达300%,这造成了电池在充放电过程中电极材料迅速坍塌,导致了电池的循环寿命大大缩短。为了解决这一问题,本文研究了一种通过水热方法,使石墨烯和碳、硅形成一个双层包覆的三维导电网络结构。实验证明,这种Si/C/G(Si/carbon/graphene)三层结构作为锂离子电池负极材料,表现出了优越的电化学性能,比如超长循环寿命、超大充放电倍率等。这种结构的电极片以0.2 A/g的电流密度充放循环50次,比容量在2469 mA·h/g以上;2 A/g的电流密度充放循环300次,比容量保持在1500 mA·h/g以上;此外在超大电流密度32 A/g的情况下测试,比容量保持在471 mA·h/g,并且具有超强的恢复能力,表现出了卓越的倍率性能,说明这种三维导电网络结构复合材料增加了原始材料的强度韧性及导电性。可见,本工作采用的方法、设计的复合材料结构在很大程度上抑制了硅材料作为负极材料的体积效应,在锂离子电池电极材料的研究发展上具有一定的借鉴意义。

锂离子电池健康状态评估方法研究进展

电化学储能是现代电力系统中不可缺少的一环,其特点是能量密度大、响应速度快、转换效率高、建设周期短、站址选择多等。储能电站的应用场景非常宽泛,如在电源侧平滑出力波动及处理跟踪、电源调频辅助服务、备用电源等;电网侧用来参与电网调峰调频、优化电网潮流分布、改善电能质量、虚拟电厂、延缓输电设备拥堵升级、微网等;用户侧可以完成削峰填谷、智能交通、社区储能、需量电费管理等。储能电站在快速发展的同时,安全是第一要素。而储能系统安全的关键在于电池系统的安全,在于如何精确预估电池的健康状态。储能电站电池的健康状态评估对电站的日常维护成本、健康运行及运维工作量等起关键性作用。综述了电池健康状态SOH(state of health)的影响因素,分析了线性误差预测方法、粒子群结合BP神经网络法、动态贝叶斯网络法的研究过程及结论验证,探讨了不同评估方法的可行性。在完善电池健康状态评估算法理论体系、实际应用技术研究方面具有潜在价值。

GB/T 19963-2011《风电场接入电力系统技术规定》解读（英文）

Introduction Unlike foreign countries,the wind power generation in China has taken on many significant features in its initial period including centralized integration,high voltage connection,long-distance transmission,inter-regional utilization,etc.With strong randomness,fluctuation and opposite peak regulation,the largescale wind power integration has brought increasing impact to

Special report on relationship between wind farms and power grids

The installed capacity of a large scale wind power plant will be up to a number of hundreds MW, and the wind power is transmitted to load centers through long distance transmission lines with 220 kV, 500 kV, or 750 kV. Therefore, it is necessary not only considering the power transmission line between a wind power plant and the first connection node of the power network, but also the power network among the group of those wind power plants in a wind power base, the integration network from the base to the existed grids, as well as the distribution and consumption of the wind power generation by loads. Meanwhile, the impact of wind power stochastic fluctuation on power systems must be studied. In recent years, wind power prediction technology has been studied by the utilities and wind power plants. As a matter of fact, some European countries have used this prediction technology as a tool in national power dispatch centers and wind power companies.

Experimental Study on Branch and Diffuse Type of Streamers in Leader Restrike of Long Air Gap Discharge

One of the main problems in the Ultra High Voltage （UHV） transmission project is to choose the external insulation distance, which requires a deep understanding of the long air gap discharge mechanism. The leader-streamer propagation is one of most important stages in long air gap discharge. In the conductor-tower lattice configuration, we have measured the voltage, the current on the high voltage side and the electric field in the gap. While the streamer in the leader-streamer system presented a conical or hyperboloid diffuse shape, the clear branch structure streamer in front of the leader was firstly observed by a high speed camera in： the experiment. Besides, it is found that the leader velocity, width and injected charge for the branch type streamer are greater than those of a diffuse type. We propose that the phenomenon results from the high humidity, which was 15.5-16.5 g/m3 in our experiment.

Comparison of two types of persistent heavy rainfall events during sixteen warm seasons in the Sichuan Basin

本文筛选出四川盆地西部(盆西型)和盆地东部(盆东型)持续性暴雨个例,深入对比两类持续性暴雨的大气环流特征和直接造成持续性暴雨的西南低涡维持的机理.四川盆地的短波槽和西太平洋副热带高压的配置有利于持续性暴雨的维持,盆东型的降水强度较盆西型个例强,高空急流位置偏南,南亚高压的强度更强,高层辐散更强,对流层中层副热带高压偏东偏南.盆西型的水汽输送主要来自南海,而盆东型的水汽输送主要来自南海和孟加拉湾.合成涡度收支的结果表明散度项是两类持续暴雨中西南涡维持的主要原因,但盆西型中,垂直平流的作用更强.

国内外分布式电源并网标准对比分析（英文）

The introduction of international,Chinese and foreign standards for distributed resources integration is presented in this paper.The typical standards in North America,Europe and China are compared in several key aspects,and then the causes for their differences and the development trends of such standards

外包工程高风险作业“六步法”安全管理标准实践与探索（英文）

In accordance with the "six-step method",the unremitting improvement of all steps in safety management may result in effective reduction of safety risk in outsourcing operations to ensure the whole operation is carried out in a safe and well-organized way.

Study on the Effect of Multi-Type Current Transformers Hybrid Operation on Differential Protection of the Bus Based on Dynamic Simulation

This paper analyzes characteristics of multi type current transformers hybrid operation for each branch of the bus and their effects on differential protection of the bus. By theoretically analyzing transmission characteristics of multi type current transformers and their influence factors, we study the dynamic model testing method of multi type current transformers for the bus, and design 3 kinds of testing schemes by making the equivalent model based on the field of P-level current transformer, TPY-level current transformer and electronic current transformer, and build the hybrid operation testing platform of multi type current transformers. Finally, we compare and analyze the transmission characteristics difference of multi type current transformers on the same branch and the characteristics difference of hybrid operation in two successive external faults, analyze the cause behind the differences, and put forward the corresponding improvement measures.

Fengyun-4 Geostationary Satellite-Based Solar Energy Nowcasting System and Its Application in North China

Surface solar irradiance(SSI)nowcasting(0-3 h)is an effective way to overcome the intermittency of solar energy and to ensure the safe operation of grid-connected solar power plants.In this study,an SSI estimate and nowcasting system was established using the near-infrared channel of Fengyun-4A(FY-4A)geostationary satellite.The system is composed of two key components:The first is a hybrid SSI estimation method combining a physical clear-sky model and an empirical cloudy-sky model.The second component is the SSI nowcasting model,the core of which is the derivation of the cloud motion vector(CMV)using the block-matching method.The goal of simultaneous estimation and nowcasting of global horizontal irradiance(GHI)and direct normal irradiance(DNI)is fulfilled.The system was evaluated under different sky conditions using SSI measurements at Xianghe,a radiation station in the North China Plain.The results show that the accuracy of GHI estimation is higher than that of DNI estimation,with a normalized root-mean-square error(nRMSE)of 22.4%relative to 45.4%.The nRMSE of forecasting GHI and DNI at 30-180 min ahead varied within 25.1%-30.8%and 48.1%-53.4%,respectively.The discrepancy of SSI estimation depends on cloud occurrence frequency and shows a seasonal pattern,being lower in spring-summer and higher in autumn-winter.The FY-4A has great potential in supporting SSI nowcasting,which promotes the development of photovoltaic energy and the reduction of carbon emissions in China.The system can be improved further if calibration of the empirical method is improved.

光伏标准助推并网检测国际化（英文）

Ever since the National Solar Energy Center(NSEC)of CEPRI started operation in June 2010,it has cooperated with many domestic certification organizations including China General Certification Center(CGC),China Quality Certification(CQC)and foreign ones such as TüV and UL through its ongoing efforts.Therefore,NSEC has gained more opportunities to go abroad,showcasing its methods,ideas and capability of testing to the world and learning advanced foreign technologies to further improve its own capability.

光伏发电并网系列技术标准解读（英文）

The five national standards on grid integration of photovoltaic power generation,jointly released by SAC,MOHURD and AQSIQ and officially implemented in 2013and 2014,are playing fundamental roles in ensuring the safe and smooth running of electric power systems connected with photovoltaic power plants,aiming at avoiding the frequent off-grid incidents,which occurred in wind power generation and improving the performance of the grid integration of photovoltaic power generation.

检测互认助推企业走出国门（英文）

As Chinese wind power equipment manufacturers have continuously improved the variety and quality of products,they are reaching out to the international market,and cooperate with global wind power companies,exporting a number of wind turbines overseas.To help domestic wind power enterprises improve global competitiveness,Chinese wind power testing institutions have actively upgraded the testing capability,realizing the cooperation and mutual recognition with international first-class testing institutions.

调度运行支持体系 助力新能源可持续发展(英文)

The ultimate goal of renewable energy integration is to generate power.Based on the safe operation of power system,the renewable energy dispatching can reserve running space through forecasting result of renewable energy operation to achieve the maximum available capability.Due to the difficulties of power system balance raised by volatile renewable energy and inflexible thermal power operation,a tough problem of dispatching is how to harmonize the renewable energy and grid safe operation.

External Insulation Correction for Power Systems in High Altitude Areas —— New IEC Proposal

With the rapid development of economy in China,India and some developing countries,the rapid increase of electricity demand will strengthen the power grid construction in special operation environments constantly,among which,the more typical special operation environment is high altitude operating condition.