One Step on the Smart Grid Path： Load and Generation Coordination in a Virtual Power System

Worldwide the introduction of dispersed generators （DG） in the distribution network is assuming a significant importance. There is an increasing relevance of the energy process efficiency improvement; as for electric power systems, the most interesting perspective concerns the capability of the system to increase the exploitation of the renewable resources. The integration of DGs in the electric distribution network requires a revision of this infrastructure, so far designed and developed assuming that power flows in one direction： from the high voltage transmission network to the medium voltage distribution, to reach final customers on the low voltage network. The attention to an efficient operation of distribution networks is increasing all over the world; this interest is becoming higher and higher also in Italy, where the high energy prices push in the direction of fostering efficiency as much as possible. This work describes a study developed in the AlpEnergy project framework： an International Cooperation Program aimed at introducing an efficient operational model for the distributed production and consumption. In particular it is proposed a new model for the integration and the management of the DG in the distribution network. The new model （defined VPS： Virtual Power System） is based on a communication channel between the active users （generators）, the loads and, eventually, the Distribution System Operators （DSOs）.

Electric power generation technology of natural gas pressure reduction:Insights from black box-gray box hierarchical exergy analysis and evaluation method

Based on the“three box”exergy analysis model,a black box-gray box hierarchical exergy analysis and evaluation method is put forward in this paper,which is applied to evaluate the power generation technology of differential pressure produced by natural gas expansion.By using the exergy analysis theory,the black box-gray box hierarchical exergy analysis models of three differential pressure power generation technologies are established respectively.Firstly,the“black box”analysis models of main energy consuming equipment are established,and then the“gray box”analysis model of the total system is established.Based on the calculation results of exergy analysis indexes,the weak energy consumption equipment in the whole power generation process is accurately located.Taking a gas field in southwest China as an example,the comprehensive energy consumption evaluation of the three power generation technologies is carried out,and the technology with the best energy consumption condition among the three technologies is determined.Finally,the rationalization improvement measures are put forward from improving the air tightness,replacing the deflector and reducing the flow loss.

Constructal design of a rectangular porous fin considering minimization of maximum temperature difference and pumping power consumption

A heat dissipation model of a rectangular porous fin is established based on constructal theory. First, the constructal design of rectangular porous fin is conducted by selecting a complex function minimization, which composed of linear weighting sum of maximum temperature difference and pumping power consumption, as optimization objective. Effects of gap height, air inlet velocity, total porous fin volume and porosity on the optimal constructs are investigated, respectively. The findings show that the complex function can attain its double minimum at a value of 0.802 when the fin length and number are optimized, and the corresponding optimal fin length and number are 8.01 mm and 10, respectively. In comparison to original design, the complex function and maximum temperature difference after twice optimization are decreased by 19.80% and 66.31%, respectively.Second, the comprehensive performance of porous fin is improved by simultaneously optimizing the fin length and number. The artificial neural network is applied to predict the fin performances, which is used to conduct multi-objective optimization based on NSGA-II algorithm. Optimal structure of porous fin for multiple requirements is gained by LINMAP and TOPSIS decisionmaking strategies. The findings in this study can serve as theoretical guides for fin thermal designs of electronic devices.

Current State and Prospect of China Natural Gas Industry

Natural gas output remained stable growth and reached 130.9 billion cubic meters in 2015, 3% higher than the same period last year. Shale gas saw huge progress. China titus became the third country in the world fu!filling commercial development after U.S. attd Canada. Natural gas import growth and growth rate declined obviously, and the imported pipeline gas and LNG totaled 61.2 billion cubic meters in 2015. Apparent natural gas consumption was 186.5 billion cubic meters in 2015, rising by 4.4% as compared with the same period last year, but it hit a historic low. There is higher dozonward pressure on domestic macro economy in 2016. However, natural gas demand will see more rapid growth, propelled by such favorable factors as gas price regulation and environmental protection policies. It is prospected that natural gas market will take a turn for the better than in 2015, and natural gas supply will still be rich in general in 2016.

Design of transit-time difference ultrasonic heat meter based on TDC-GP21

According to the transit-time difference measurement method,we proposed a design scheme of ultrasonic heat meter based on TDC-GP21.The measurement unit TDC-GP21 mainly completes transit-time measurement and inlet,outlet temperature measurement functions.Control unit and data processing unit based on MSP430F4152 of TI corporation complete functions including peripherals control,data analysis,temperature compensation algorithm,flow pattern compensation algorithm and low power consumption control.The design meets the Town Construction Professional Standard CJ 128-2007,and furthermore,some performances can be improved.

UEs Power Reduction Evolution with Adaptive Mechanism over LTE Wireless Networks

At present, the major drawback for mobile phones is the issue of power consumption. As one of the alternatives to decrease the power consumption of standard, power-hungry location-based services usually require the knowledge of how individual phone features consume power. A typical phone feature is that the applications related to multimedia streaming utilize more power while receiving, processing, and displaying the multimedia contents, thus contributing to the increased power consumption. There is a growing concern that current battery modules have limited capability in fulfilling the long-term energy need for the progress on the mobile phone because of increasing power consumption during multimedia streaming processes. Considering this, in this paper, we provide an offline meaning sleep-mode method to compute the minimum power consumption comparing with the power-on solution to save power by implementing energy rate adaptation(RA) mechanism based on mobile excess energy level purpose to save battery power use. Our simulation results show that our RA method preserves efficient power while achieving better throughput compared with the mechanism without rate adaptation(WRA).

Optimal Thermal Insulation Thickness in Isolated Air-Conditioned Buildings and Economic Analysis

The removal building heat load and electrical power consumption by air conditioning system are proportional to the outside conditions and solar radiation intensity. Building construction materials has substantial effects on the transmission heat through outer walls, ceiling and glazing windows. Good thermal isolation for buildings is important to reduce the transmitted heat and consumed power. The buildings models are constructed from common materials with 0 - 16 cm of thermal insulation thickness in the outer walls and ceilings, and double-layers glazing windows. The building heat loads were calculated for two types of walls and ceiling with and without thermal insulation. The cooling load temperature difference method, CLTD, was used to estimate the building heat load during a 24-hour each day throughout spring, summer, autumn and winter seasons. The annual cooling degree-day, CDD was used to estimate the optimal thermal insulation thickness and payback period with including the solar radiation effect on the outer walls surfaces. The average saved energy percentage in summer, spring, autumn and winter are 35.5%, 32.8%, 33.2% and 30.7% respectively, and average yearly saved energy is about of 33.5%. The optimal thermal insulation thickness was obtained between 7 - 12 cm and payback period of 20 - 30 month for some Egyptian Cities according to the Latitude and annual degree-days.

Current Situation and Prospects of the Development of China’s Natural Gas Industry

In 2018,China's natural gas market reached a new level of development,with apparent consumption of 280.3 billion m3,up by 18.1%over the same period in the previous year.Domestic production grew steadily,reaching 157 billion m3,up by 7.2%over the same period in the previous year.Natural gas imports grew rapidly,with imports of pipeline gas and LNG totalling 124.2 billion m3.In terms of trade types,imports of LNG continue to exceed those of pipeline gas.In 2019,there has been downward pressure on the macro economy,and the development of the main gas sector has slowed down.Driven by environmental protection policies,the natural gas market continues to maintain rapid growth.However,it is difficult for the levels of increment and growth to reach those of the previous two years,and the growth rate of market demand is predicted to reach 10.7%.

低功耗硅基OLED微显示器的区域梯度调光策略

针对近眼显示设备存在显示功耗较大的问题,通过研究人眼视觉的特性提出一种人眼凝视点自适应的区域梯度调光算法。首先进行中心凹-亮度掩蔽实验以获取人眼的恰可觉差(Just Noticeable Difference,JND),并在此基础上改进了传统人眼凝视点的几何光路模型,得到更符合人眼自适应特性的几何光路模型,引入最大视角判别法有效提高了视角计算效率。随后,对图像进行预处理时采用改进的对比度增强算法,以在保持图像平均显示亮度基本不变的情况下增强显示效果。根据实验得到的JND阈值和凝视点信息,对图像实施了区域和全局功耗限制,从而在降低功耗的同时保持了视觉主观感受。在FPGA硬件平台上完成了算法的验证。实验结果表明,该算法在柯达标准测试集下使硅基有机发光二极管(Organic Light Emitting Diode,OLED)微显示器的显示功耗降低23.05%,基本满足硅基OLED微显示器的低功耗显示的要求,可为其性能提升提供指导。

光伏微网储能系统用电峰谷差自适应控制技术

光伏微网储能系统(PMESS)用电峰谷差的增大会导致电网负荷波动增大,影响电网的稳定性。为了有效降低电网的峰谷差,提出一种光伏微网储能系统用电峰谷差自适应控制技术。通过估计光伏微网发电系统的负荷,计算光伏微网储能系统的充电功率和电量,并根据该计算结果计算光伏微网储能系统的额定容量。设置用电峰谷差自适应控制约束条件,并结合二轮迭代的方式实现光伏微网储能系统用电峰谷差自适应控制。实验结果表明,所提技术可以准确估计光伏微网发电系统负荷,并将用电峰谷差控制在200 kW左右,同时,可以有效提升光伏微网储能系统的有功功率,具有良好的实际应用效果。

基于时差法的低功耗超声波三维海流测量系统

声学时差海流计具有高精度、高采样率、无盲区和不受海洋散射条件限制的优点,目前国内尚无时差海流计系统样机以及核心部件(四声道双晶换能器)的报道。为了实现对海洋矢量流速的长期精确测量,设计并研制了基于时差法的低功耗超声波三维海流测量系统,构建了四声轴三维矢量流速测量模型,通过有限元仿真设计并制备了小体积异形异构V形双晶换能器。系统采用低功耗STM32L431和MSP4306288为主控芯片,由TDC-GP22高精度时间测量模块、换能器驱动电路、低功耗放大滤波电路、SD卡存储模块等组成测量电路,通过测量换能器4个声轴上的超声波飞行时间差,得到海水的三维矢量流速。系统采用低功耗硬件系统设计,配合软件低功耗管理降低系统功耗。经实际测试,所研制的三维海流测量系统具有测量准确、低功耗、存储方便等优点。

基于循环神经网络的异常用电数据检测方法

针对用电数据检测时受电量敏感度的影响,导致异常数据检测时电能消耗过量的问题,提出了基于循环神经网络的异常用电数据检测方法。在循环神经网络体系中,根据窃电系数指标求解结果,计算电量压差的实际数值,实现对异常用电数据特征的提取。构建异常数据样本集合,通过填充缺失数据的处理方式,推断检测评价指标所属区间范围,完成基于循环神经网络的异常用电数据检测方法的设计。对比实验结果:循环神经网络作用下,由异常用电数据造成的电能消耗量最高为3.2×10^(8)kW·h,不会引发明显的电能过量消耗问题,符合维护电网运行稳定性的实际应用需求。

再论中小学变压器指标调研

根据近年来中小学工程设计,对现阶段不同类型的中小学校在不同季节、不同时间段、不同类别建筑用电情况进行调查、研究、总结,绘制调研中小学的全年总用电量变化曲线图,不同季节某日变压器负载变化曲线图,教学楼、宿舍、食堂等不同类型建筑不同季节某日用电功率变化曲线图,分析其特点,总结调研学校各类别用电负荷的单位面积用电量指标、用电时段、需要系数,供设计参考。

Performance analysis of a solar-aided power generation(SAPG) plant using specific consumption theory

In contrast to a traditional coal-fired power generation plant where steam extracted from a turbine is used to preheat the feedwater in all preheating stages, a solar-aided power generation(SAPG) plant uses solar heat to replace a part or all of the extracted steam in one or more preheating stages. The performance of an SAPG plant with different replacements is investigated in this study by using specific consumption theory(SCT). Fuel-specific and cost-specific consumption models for SAPG plants are built based on the SCT. A typical 330 MW coal-fired power plant is used as the study case. The performance of the SAPG plant in terms of specific consumption, with steam obtained from the first through the eighth(except for the fourth) stages of extraction replaced by solar heat, is compared with that of the reference coal-fired power plant. The fuel-specific consumption of the SAPG plant is determined to be lower than that of the reference coal-fired power plant. The fuel-specific consumption accrual distribution in SAPG plants is used to assess the effect of each individual replacement. Effective strategies to reduce the specific costs of the SAPG and coal-fired power plants are proposed based on the results of this study.

济南黄河滩区某地源热泵供暖制冷工况运行参数对比

对地源热泵系统运行情况进行测试是了解热泵系统运行与能耗的重要手段。通过对某地源热泵工程冷热工况运行数据的统计分析,讨论了冷热工况下耗电量、地源侧供回水温差、室内外温度差和能效比之间的相互关系,得出:在用户侧供回水温差基本一致的情况下,地源侧供回水温差越大,机组运行的能效比越高,相应的耗电量就越小。

考虑需求响应与火蓄调峰的优化调度模型研究

为了应对风电等可再生能源接入引起的系统调峰压力增大且影响系统经济运行的问题,进一步挖掘新型调节电源、传统调节电源和负荷侧协同调峰的潜力,综合利用负荷侧的需求响应和电源侧的抽水蓄能、火电三种调峰措施联合调峰,构建考虑需求响应和火蓄参与深度调峰的电力系统两阶段优化调度模型。第一阶段优化模型中引入负荷侧的需求响应,以最小化负荷与风电差值的平方之和为目标,优化负荷曲线,降低系统峰谷差;第二阶段优化模型利用电源侧的抽水蓄能和火电深度调峰,计及火电深度调峰电量损失成本、抽蓄调峰成本和弃风成本,以系统总运行成本最小为目标,在第一阶段模型的基础上优化各机组出力,增加风电上网空间。以改进的IEEE30节点系统进行算例分析和两阶段优化模型有效性验证,结果表明,所建模型可提高调峰能力,促进风电消纳,并降低系统总运行成本。火电机组进一步降低出力,积极参与深度调峰,能够有效促进系统风电消纳。三种调峰方式有机结合联合参与调峰,降低了负荷的峰谷差,不仅有效降低了弃风率,还减轻了系统的调峰压力,缩短了火电深调时段。

加热器上、下端差对机组煤耗影响的通用计算模型

根据热力系统热平衡方程、比内功方程、循环吸热量方程及发电标准煤耗率计算公式,导出了加热器下端差对机组煤耗影响的通用计算模型;并且在考虑到加热器下端差的影响的基础上,改进了以往的建模方法,得到了更为完善的加热器上端差对机组煤耗影响的通用计算模型。计算实例表明,这两个模型具有计算结果准确、使用方便简捷、通用性强等特点,这为火电机组节能降耗的分析工作提供了一种新的工具,具有重要的实际意义。

热电冷联产与分产能耗比较分析

将热电冷联产与分产能耗比较分解为供热、供电、供冷三种煤耗差进行分析 ,建立了以分产为基准的三种煤耗差计算公式 ,探讨了煤耗差随热、冷负荷的变化情况 ,给出了目前一般情况下联产的节能条件、判据及措施。