查询词典 convection current

Due to capacity increase or structure change of the power system, an extra-high current possibly 100 times of the rated current may appear in some circuits of the power system when a short-circuit fault happens nearby. This current is extra high and exceeds the permitted value of 10% error curve of protection current transformer.

在电力系统中，各回路的最大故障短路电流和额定工作电流的比值应在合理的范围内，以保证保护用电流互感器的工作精度，但由于系统容量增大或因系统结构等原因，某些回路在某些情况下的最大故障短路电流远远超过了正常范围。

Moreover, second-winding current waveform of a current transformer is calculated under the transient current of the typical short-circuit fault by numerical method. The analysis shows that the relevant protection equipment may refuse to trip when the fault current is extra high. It will result in the maloperation of protective relays for loss of their selectivity, and cause other protective relays to operate beyond range, and extend the scope of shutdown of power supply.

在这些回路出口处发生相间直接短路等严重故障时，流过相应TA一次侧的故障电流可能达到TA额定工作电流的100倍以上，大大超过了保护用TA的10%误差容许倍数，将使TA严重饱和，从而影响相关的保护设备的动作性能，因此有必要对在这种特大电流作用下的TA的传变特性做一些探讨，以分析其对继电保护装置动作特性的影响及应采取的措施。

We have found that, within the physical ranges of the model parameters, the correlation functions of hole hoppings giving rise to closed current flow patterns in the circulating current phases are substantially larger than those of hole hoppings corresponding to open current flows. This provides the evidence for the existence of the circulating current phases in the three-band Hubbard model.

通过模拟发现，对应于闭合曲线的关联函数在同一距离上要比其他所有没有闭合的关联函数大得多，因此证明在三带Hubbard模型中存在环形电流相。

Using harmonic analysis of the calculated tidal level and current, the distributions of co-tidal lines for K1, O1, M2 and S2 are obtained, whose maximum amplitudes can reach 112 cm, 96 cm, 50 cm and 15 cm, respectively. The distribution of the maximum probable current velocities in Qinzhou Bay is basically the same as that of isobaths, and the maximum probable current velocity can reach 200cms^(-1) nearby the Longmen Harbor. It is concluded by the analysis of K1 and M2 tidal current ellipses that the flow is rotating at the mouth of the bay, while its retilinear flow is in the nearshore area, estuaries and channels. The distributions of the major axes are closely related to the topography, and the rotation directions of both constituents are clockwise.

根据模拟结果计算得到了较以往更为精细的钦州湾K1、O1、M2、S2分潮的同潮图，潮汐最大振幅分别为112、96、50和15cm；最大可能流速的分布基本与等深线一致，龙门港附近最大可能潮流流速可达200cms^(-1)；钦州湾的外湾口海域开阔，一般为旋转流，近岸海区及水道、河口等多为往复流，K1和M2分潮流椭圆长轴的分布与地形密切相关，旋转方向均为顺时针，流速极值出现在龙门港区。

Other conclusion include: the trip of transient protection must be locked when the power circuit breaker of transimission line operated,because the trip is incorrect at this time;the features of transient current and its energy is different between the fault and thunder over- voltage in transimission line,and them can be identified;the ratio of high frequency component of current in serise capaciters compensation line , SVC and HVDC system is far little than fault transient current, so all of them do not affect the working of trasient current protection.

研究了在串联补偿电容的输电线路上发生故障时，串联补偿电容的MOV非线性保护电路对暂态保护的影响。串补电容MOV保护电路的非线性电流高频分量含量很小。静止补偿器、高压直流输电系统换流器的非线性特性产生的谐波分量含量极少。仿真计算表明，在与暂态保护判据中高频分量对应的频率范围内，其电流对应的功率谱估计值大大低于线路故障时故障电流的功率谱估计值，因此它们都不会对暂态电流保护的正常工作产生影响。

In this paper, the rotary spectra of sea current and residual current are calculated for the data of cunent vector time series acquired through a mooring buoy located at (114°20.5'E, 20°04.8'N). Subsequently, the preliminary analysis for the internal structures of current in this area is done from these results of calculation and a lesidual current with a three days period is found in this sea area.

本文利用本所水文气象研究室在东沙群岛西南海域投放的一个锚定浮标(114°20.5′E，20°04.8′N)所获得的一系列海流流速矢量观测资料，用旋转谱分析方法对该站海流的内部结构作初步的探讨，并由此得到该站海流的某些运动学特征。

The boost converter is a voltage step-up and current step-down converter .the current source is synthesized from a DC voltage source by adding a large value inductor in series .in DC regulated power supply applications ,the voltage sink represents a large value capacitor in parallel with the load resistance .in the application of the DC motor control ,the voltage sink represents the back emf of the DC motor .the switching action produces a pulsating current .the capacitive filter smoothens the pulsating current and provides a DC voltage to the load

升压转换器是一个升压和降流的转换器。电流源是一个直流电压源添加一个大值电感串联合成的。在直流稳压电源的应用，电压降代表一个大值电容并联一个负载电阻。在直流电机的控制应用中，电压降代表反电动势的直流电机。转换行为产生一个脉动电流。一个滤波电容是这个脉动电流平和并且提供直流的电压负荷。

According to the experimental data, it can be seen that the current transformer this paper designed could work reliably. At the range of -40~70 oC, it can work steadily. Furthermore the ratio error and phase error of current transformer could satisfy the state criterion of 0.2 standard. Relative to the tradition electromagnetic current transformers the respond speed and bandwidth are increased greatly. As a result, it is hopeful that the electronic current transducer we designed is practical.

经试验验证，本课题设计的电子式电流互感器工作可靠，在-40~70 oC温度范围内均能稳定工作，而且其比差和相差都满足国标中对 0.2 级电流互感器的要求，其动态响应速度、带宽等性能明显比传统电磁式电流互感器有很大的改进，因此其有望很快进入实用化阶段。

The principle of the novel single-phase hybrid active power filter is described in detail. Based on the above analysis, Kalman filtering approach for estimation of harmonics is presented to improve the speed and precision of harmonic detection, and it also can avoid the influence made by voltage distortion on harmonic detection. A new current control strategy based on energy balance is presented to regulate the active part absorbing or releasing active power and control the inverter to produce current opposite to the harmonic current reflowing in injection branch, the above method combined with harmonic current tracking control that keeps the stabilization of dc-side voltage and improve the reliability of the system.

并详细分析了系统的滤波原理，提出了基于卡尔曼增益自调整的改进型动态谐波含量估计方法，能够快速准确的跟踪检测电网谐波电流，并且克服了电力机车等冲击性负荷引起的电网电压畸变对谐波检测精度的影响；提出了基于逆变器两侧能量平衡的电流控制方法使有源部分吸收或释放一定有功或无功功率及产生与注入支路回灌谐波电流相反的抑制电流，然后联合电网谐波电流跟踪控制以获得系统参考信号，保证了直流侧电压的稳定，提高了装置可靠性，增强了系统滤波性能。

At first the current sampling values pass through virtual digital CVTs. And then the voltage and current sampling values are processed by a low pass filter. According to the instantaneous value of transmission line voltage, the current instantaneous values of shunt reactors and P equivalent circuit capacitance can be calculated. After removing these two kinds of current, sampling value differential protection based on all components and fault component can be applied.

由线路电压瞬时值分别实时计算出流入并联电抗器和流入线路Π型等值电路两侧电容的电流瞬时值，再从线路每侧电流除去这两部分电流，用得到的新电流瞬时值作常规采样值差动和故障分量采样值差动保护计算。

Listen,point and check your answers.

听，指出并且检查你的答案。

Warming needle is one of effective treatment methods for knee arthralgia aggravated by cold,and it is simple,safety,so it should be developed in clinical acupuncture and moxibustion extensively.

但以本院科针灸门诊在2005年1月—2006年6月期间共收治膝痛患者100余例，经过临床的诊断后，其中施以温针治疗的48例，疗效显著，报道如下。1临床资料本组病例48