Allocation and sizing of battery energy storage system for primary frequency control based on bio-inspired methods: A case study

This paper presents a new procedure for optimal allocation and optimal sizing of a battery energy storage system (BESS) for primary frequency support in an isolated power system. For the BESS allocation, a transmission bus system with larger frequency decline is recognized and the BESS sizing is performed by a constrained optimization strategy based on a new modified metaheuristic, called Developed Harris Hawks Optimization (DHHO). The simulation results of the suggested DHHO are compared with Bat Optimization Algorithm (BOA) and Genetic Algorithm (GA) from the literature to show the method efficiency. The final results showed higher precision with lower required iterations for the suggested DHHO method. Also, the proposed DHHO gives lower investment costs for BESS with lower power and energy requirement toward the other compared methods.     

Fundamental Evaluation of Power Supply and Rectifiers for Wireless Power Transfer Using Magnetic Resonant Coupling

This paper provides a fundamental analysis of a power supply and rectifiers for wireless power transfer using magnetic resonant coupling (MRC). MRC enables efficient wireless power transfer over middle‐range transfer distances. MRC for wireless power transfer should operate at a high frequency in the industry science medical band, such as 13.56 MHz, because the size of the transfer device decreases at higher transfer frequencies. Therefore, the output frequency of the power supply on the transmitting side should be 13.56 MHz. In addition, the rectifier on the receiving side is operated at a high frequency. This paper focuses on the reflected power in the power supply and rectifiers. Thus, the parametric design method is clarified for the power supply, including a low‐pass filter to match the output, the impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects on the rectifiers of silicon carbide and gallium nitride diodes are confirmed by performing an experiment and a loss analysis.     

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.     

中高压变频器冷却方案比较和选型分析

随着电力电子器件的发展,性能优异的中高压变频器在各行各业中得到越来越广泛的应用,能否处理好变频器的散热问题是其长期稳定运行的关键。分析了中高压变频器热量产生来源,并从技术可行性、可靠性、经济性等角度对不同冷却方案的特点进行比较,并结合实际的工程案例,给出合理的变频器冷却方案选型建议,可作为工程电气设计时中高压变频器冷却方案选型参考。     

基于ARM7的高精度频率计的设计

文章通过对相位重合检测技术的分析，提出了基于此理论并用ARM7作为主控芯片的高精度频率计的设计方法。该设计方法通过捕捉相位之间的重合点，能够有效消除±1个字的计数误差。在此基础上由于ARM7具有32位的处理器内核以及流水线技术，使得频率计的测量速度和精度比传统的使用16位单片机设计的频率计要高很多。本频率计最大测量频率为10MHz。同时本设计采用安捷伦公司生产的恒温晶振10811A作为标准频率，能够有效保证测量精度能够达到10-10量级。为了降低成本，在设计中选用采用ARM7芯片内部的计数器以及用简单的逻辑电路进行设计。由于其测量精度要超过多周期同步测量法，而成本又比模拟内插法和游标法低很多，因此此频率计拥有很广泛的市场前景。     

对《称重传感器》国标5.2.1条款

通过对《称重传感器》国标仔细研读和分析,在标准规定的三段最大允许误差限基础上,提出了五段式最大允许误差限和分段点必检的观点,从而满足了5.2.1提出的全量程、全分度的检定要求。     

Ni-based catalysts with coke resistance enhance by radio frequency discharge plasma for CH4/CO2 reforming

Coke deposition has been considered to be one of the most important reasons hindering the stability of the catalyst during CH₄/CO₂ reforming. In this study, after the addition of P123 (PEG-PPG-PEG triblock copolymer), Ni²⁺ can be well-dispersed on the mesoporous molecular sieve MCM-41. And then, the catalysts were prepared by using N₂ radio frequency (RF) discharge plasma for different treatment times to reduce the size of Ni particles, improve the anti-coking performance, and thereby improve the stability of the catalyst. The results showed that the catalyst NM-P123-PN2h exhibits superior catalytic properties in the CH₄/CO₂ reforming. The initial conversions of CH₄ and CO₂ were 90.80% and 89.60% at 750 °C, respectively. The catalyst NM-P123-PN2h showed highly coke resistance with less carbon deposition (1.12%) at 750 °C after 10 h of continuous reaction, while the carbon deposition of the catalyst NM-C was 37.32%. Compared with the traditional calcination method, the catalyst prepared by plasma treatment has a smaller particle size and better dispersibility of nickel. In particular, the nickel particle size of the catalyst NM-C was 8.37 nm, however, that of the catalyst NM-P123-PN2h was only 1.70 nm, and the nickel particle size was reduced by 5 times. Therefore, it can be concluded that the catalyst prepared under the combined action of P123 and RF plasma-treated can effectively improve the coke resistance of the catalyst and the stability of the CH₄/CO₂ reforming.     

Comparison of the dynamic responses of monopiles and gravity base foundations for offshore wind turbines in sand using centrifuge modelling

Monopiles and gravity base foundations (GBF) are two of the most commonly used foundations for offshore wind turbines. As resonance can cause damage and even failure of wind turbines, understanding the difference between the dynamic responses of monopiles and GBFs under free vibration is important. However there is little experimental data regarding their natural frequency, especially from model tests carried out at correct stress levels. This paper presents the results of novel monopile and GBF tests using a centrifuge to directly determine the natural frequency (f_n) of the foundation-soil system. The natural frequencies of wind turbine monopiles and GBFs in centrifuge models were measured during harmonic loading using a piezo-actuator, with the results confirming that soil-structure interaction must be considered to obtain the system’s natural frequency as this frequency reduces substantially from fixed-base values. These results will contribute in preventing resonance induced damage in wind-turbines.     

钢轨交流闪光焊接过程过梁爆破特征分析

以高速摄影技术作为主要研究手段，研究钢轨交流闪光焊接过程过梁爆破特征，并结合热成像系统采集焊接过程温度场，以此为数据基础定量分析了钢轨交流闪光焊接过梁爆破特征. 结果表明,钢轨交流脉动闪光焊接工艺模式下，加速闪光阶段具有几个阶段中最高的闪光频次46.93次/s，脉动闪光阶段具有最低的闪光频次11.07次/s；连续闪光阶段闪光烈度为0.009 2 mm/次，是几个阶段中最强的，脉动阶段的闪光烈度最弱，为0.003 8 mm/次；从闪光加热因子来看，脉动阶段最高，符合了该阶段积累热量的主要目的；加速闪光阶段最低，是由于该阶段为了制造保护气氛产生的气化过梁带走了较多的热量；从闪光均匀度看，闪光最不均匀的阶段是闪平阶段，最均匀的阶段是脉动阶段，这恰恰说明了两待焊端面的微观平行情况在闪平阶段最差、脉动阶段最佳.     

某轻型载货车储气罐支架振动断裂分析与优化

为了有效解决某轻型载货车储气罐支架的断裂故障,首先基于建立的储气罐支架有限元模型进行振动特性分析,分析结果表明其前三阶固有频率接均处于发动机激励频率范围之外,不会产生共振。其次测试各种道路的时域载荷,测试结果表明其中角度搓板路的激励频率与储气罐支架第一阶固有频率相接近,从而引起共振,不满足振动特性要求。然后对其进行振动强度分析,分析结果表明其应力水平不达标,其最大应力点与开裂处一致。再对其进行振动疲劳寿命预测分析,分析结果表明其疲劳寿命也不达标,其危险点也与失效位置相同。再采用集成平台对储气罐支架的结构进行优化设计,优化之后其模态频率、振动强度和振动疲劳均符合性能要求,并且其重量也有所减轻,总体优化效果较佳。最后整车试验结果表明优化之后储气罐支架的振动大幅度降低,并且没有发生失效。