瞬动校验电流评价与误差分解方法

瞬动校验电流的精度直接影响断路器瞬动保护特性的整定。通常要求施加的交流校验电流为幅值阶跃变化并满足一定的精度,施加的时间有严格要求,尽量减小突加过程在回路中产生的电流非周期分量。主要研究影响校验电流精度的各种因素,通过数学分析、仿真与试验,揭示诸因素对瞬动校验电流精度影响的机理和规律。阐述了校验电流评价与误差分析方法。该试验的研究成果将为提高瞬动校验调试与试验的水平提供理论指导和技术支持,同时也为瞬态过程的控制提供了思路和方法。

全定制专用电路门级电流评价方法

文章叙述全定制专用电路设计过程中动态电流的建模及评估方法。这一工作是基于已开发的原理图逻辑仿真器及布局图性能模拟器工具在底层进行的。 电流模型库的建立为设计人员进一步分析动态功耗、计算电磁兼容指标等提供了依据。 通过样本动态电流从时域到频域的转换，与实际测量给出的频谱分析曲线对比，其结果是满意的。

埋地钢质燃气管道地铁杂散电流影响评价与排流方法探讨

本文介绍了位于地铁线路区域埋地钢质燃气管道,如何检测与评价地铁产生杂散电流产生的干扰影响,排除埋地钢质管道上杂散电流的方法探讨,以及实际应用的排除杂散电流方法经验介绍。

塑壳断路器瞬动校验电流误差分解与控制方法

针对断路器瞬动校验精度不高的问题,揭示了校验电流存在误差的原因;阐述了电流幅值误差、非周期分量误差的分解方法;提出了校验电流评价方法和逐次逼近控制方法.采用理论推导和仿真方法验证,证明了该方法的可行性.通过实际应用说明该方法能够有效消除电流误差,提高断路器瞬动校验精度.

Analysis of the integrated test and evaluation methods of tidal current energy generating devices in the offshore testing site

Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.

Evaluation of Heat and Current Characteristics of Bypass Diodes for Fault Detection in Photovoltaic Module

In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.

An Evaluation of R134a and R245fa as the Working Fluid in an Organic Rankine Cycle Energized from a Low Temperature Geothermal Energy Source

The characteristics of an organic Rankin cycle designed to operate with a low temperature geothermal source and constant temperature cooling water supplied from freshwater ponds typical to those found near Waddan City in the Al Jufrah region of Libya were examined. Two working fluids were examined and it was concluded that the most suitable for this application was R-245fa. The off design performance of the organic Rankine cycle was examined and it was shown that the cycle is controlled by the performance of the condenser which is cooling water side temperature limited.

Experimental Performance Assessment of Multi-Phase Alternators Supplying Multiple AC/DC Power Converters

DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more （iV） three-phase windings and feeds the DC load through more （N） cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number （N） of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits （in terms of DC output current quality and field current ripple） are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.

Evaluation of optimization operation models for cascaded hydropower reservoirs to utilize medium range forecasting inflow

This paper evaluates the performances of the models that incorporate forecasting inflow for cascaded hydropower reservoirs operation. These models are constructed separately on the concepts of explicit stochastic optimization （ESO） and implicit sto- chastic optimization （ISO） as well as parametefization-simulation-optimization （PSO）. Firstly, the aggregation-disaggregation method is implemented in ESO models to reduce the complexity of stochastic dynamic programming （SDP）. And the aggre- gate flow SDP （AF-SDP） and aggregation-disaggregation SDP （AD-SDP） are constructed respectively. Secondly, in ISO mod- el, decision tree is the well-known and widespread algorithm. The algorithm C 5.0 is selected to extract the if-then-else rules for reservoir operation. Thirdly, based on the PSO model, the hedging rule curves （HRCs） are pre-defined by fusing the storage and inflow as state variable. The parameters of the HRCs are determined by using the simulation-optimization model. Finally, China＇s Hun River cascade hydropower reservoirs system is taken as an example to illustrate the efficiency and reliability of the models. In addition, the values of quantitative precipitation forecasts of the global forecast system （10 days lead-time） are implemented to forecast the 10 days inflow.

Strategic Bidding Model for Power Generation Company Based on Repast Platform

： The bidding strategies of power generations in the market are a dynamic and complex problem. It is difficult to analyze and compute with the traditional mathematical methods, which is conspicuous in the middle or long-term transactions. This paper pro- poses a modelity which is the middle or long-term bidding strategy in two-tiers electricity market that is based on the optimal power flow （OPF）. Uncertainties in the outside world are regarded as the agent （Agent） of ＂external environment.＂ Under this conditions, Agent through environment evaluation judges to select viable strategic. Through learning from experiences and opponent＇s behaviors, Agent guides the purpose of the best production. The adaptability and superiority of this model is tested based on Repast with a standard IEEE-5 bus 6 notes test system.