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By means of simulation, the authors research the over-voltage level at AC and DC sides of converter station as well as arrestor operation condition caused by last breaker trip occurred in inverter station of UHVDC power transmission project from Yunnan to Guangdong; analyze and reveal the interrelations among over-voltage level, various operation conditions and different action delay of DC protections and propose the requirement to the time of protection coordination to ensure secure and reliable operation of equipments for the project.

文章对云广特高压直流系统逆变站最后断路器跳闸引起的换流站交直流侧过电压水平以及避雷器工况进行仿真研究，分析揭示不同运行工况、不同直流保护动作延时与过电压水平的相互关系，提出对保护配合时间的要求，以确保系统设备能安全可靠运行。

A DC bias of approximately 1.2V is present at this pin.A DC blocking capacitor is needed if the signal has a different DC level.

阿约1.2V的直流偏置在这个pin.A直流阻挡电容器，是目前需要的信号，如果有不同的直流电平。

For the case of PV-TW system without window-without heat storage-with/without DC fan-with periodically operating air vents and that with window-with heat storage-without DC fan-with periodically operating air vents, the system"s model is improved and expanded, and then the simulation results are compared with experimental results to validate the new model, while the effect of DC fan and window on system"s performance are further studied.

针对无窗户无蓄热有无直流风机风口按时开关工况和有窗户有蓄热无直流风机风口按时开关工况，对PV-Trombe墙系统模型进行了改进和拓展，并将模拟结果与实验结果对比，验证了改进和拓展后的模型的合理性，并进一步研究了直流风机和窗户对PV-Trombe墙系统性能的影响。

The feasibility,effectiveness and limitation of four improvement measures are studied:raise protection settings or prolong protection delay;apply inverse time limit ;use additional criterion to distinguish valve fault from AC system fault;and adjust 100 Hz protection configuration principle.

为减小交流系统故障期间直流100Hz保护动作的概率，利用PSCAD/EMTDC仿真分析软件，就阀故障和交流系统故障时直流线路50Hz/100Hz电流特性进行了分析，研究了提高保护定值或延长保护动作延时、采用反时限特性、利用附加判据区分交流故障和阀故障、调整直流100Hz保护配置原则4种措施的可行性、使用后的效果及局限性。

This paper analyzes the numerical control DC constant current source system design needs, expounded numerical-controlled DC constant current source of the hardware and software design principles, instructed the numerical-controlled DC constant current source circuit of the module function and design ideas, completed the numerical-controlled DC current source of all design, and the circuit is complete and procedures.

本文主要分析了数控直流恒流源系统的设计需求，阐述了数控直流恒流源的软硬件的设计原则，介绍了数控直流恒流源各模块电路的功能及设计思路，完成了数控直流恒流源系统的全部设计，给出了完整的电路图和程序。

Simulation results show that by means of utilizing super conductors the power output capability of DC system can be effectively improved, the service life of DC system can be elongated, thus both reliability and economy of DC system can be improved.

仿真结果表明，该方案通过采用超级电容器，能够有效提高直流系统的功率输出能力，延长直流系统的使用寿命和改善其技术经济性，从而提升直流系统的可靠性和经济性。

Because a bulk smoothing capacitor is usually installed on the DC side of many AC to DC converters, the characteristics of harmonic loads will be influenced by this capacitor. Nowadays, shunt active power filters can't reduce harmonics effectively for this voltage type harmonic-producing load. Therefore, a series active power filter is designed to meet the requirements of voltage-sourced harmonic loads. Both source current and load voltage are detected in order to reach the compensation voltage for the SAPF.

由於许多交直流电源转换器均在直流端并联一直流电容以作为稳压之用，此大电容将造成负载谐波特性的改变；此类谐波源负载，如果使用现今常见的并联型主动式电力滤波器并不能很有效解决此类谐波问题；因此本文将采用串联型主动式电力滤波器，并配合同时量测电源电流及负载电压的混合式控制模式，即可有效解决此类谐波问题。

The appearance of brushless DC motor brought the development of EPS a new opportunity. BLDCM does not only possess almost all the advantages of a DC motor, but also has a series unique advantage. The way of taking the place of DC motor by a permanent magnet coreless brushless DC motor gives a totally new method for the development of EPS in the future.

无刷直流电机的出现为电动助力转向的发展带来了新的机遇，它不仅具有几乎直流电机的全部优点，同时还具有一系列无可比拟的优势，特别是采用无铁心永磁无刷直流电机代替普通直流电机，不失为今后电动助力转向发展的一种全新思路。

From research,It is known that the flux of single-phase transformer would offset and exciting current of single-phase transformer would be distorted under DC current inrushing.

直流电流通过两个Y0连接的变压器中性点侵入电力系统，故针对三相三柱变压器直流入侵情况建立了直流入侵下的三相三柱变压器的电路模型和相应的方程，结合三柱磁路的麦克斯韦方程和非线性的B—H曲线方程，利用数字迭代法，在MATLAB环境下编程计算了三相三柱变压器直流入侵下的变压器励磁电流和谐波特征。

In order to be fit for three-phase four-wire system, the method of balancing control using chopper presented in literature [29] is mended. The new standpoint that ip-iq detecting method based on three-phase three-wire system can be directly used in three-phase four-wire system is presented and proved.

分析了零序和负序电流对新型UPFC直流侧电容电压的不同影响，对文献[29]提出的传统UPFC的直流侧各电容电压的均衡控制方法进行了仔细研究，提出了采用B型直流斩波器来控制新型UPFC的直流侧电容电压的新方法。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。