电网

The original 10 kV grid terminal user adopts emanant type,and the floor area of transformer centralized power supply and distribution mode is very large,high investment,low reliability and high energy consumption,which shows the significance and necessity for medium voltage grid to use ring network and transformer distributed power supply.

原有10kV电网终端用户采用放射式、变压器集中供配电方式占地面积大、投资高、可靠性低、不节能，指出中压电网采用环网、变压器分布式供电的重要性及必要性，比较了断路器和负荷开关-熔断器在保护终端用户变压器上的差异，对变压器的合理选用做了分析，以求做到节能和环保。

The main goal of distribution network planning is to make optimal grid plan to meet the requiremnents of system load increasement.

配电网规划的主要目标是优化电网结构以满足负荷增长的需求。

In chapter 5, the new concept of net-calculatoin, and site testing of harmonic resistance is papered out, by means of the testing of a harmonic source.

在第五章，通过对一谐波源的具体测试工作，提出了电网谐波阻抗网络计算法及电网谐波阻抗实测法的新观点。

For electric power pulsive shipping, the voltage is not always normal, especially when the main motor is starting, and three-phase bridge commutated circuit is used widely, so, a new method to compute harmonic is developed, which is more accurate and practical, is more adapt to the ship condictions.

因此，本文在上述文献的基础上，对接入电压波形畸变的电网中的三相桥式整流电路进行了分析，采用了一种实用的新方法来计算三相桥式整流器所产生的谐波电流。本方法考虑了交流侧电抗及电网中存在的谐波电压，导出了交直流两侧谐波电流的计算公式。

It produces a voltage, which has equal amplitude and opposite di rection against the distortion voltage contained in power system with PWM invert er, and then it is injected to network through transformer by lower-pass filter.

它利用PWM逆变器产生与电网畸变电压大小相等、方向相反的脉宽调制波，经低通滤波器滤除开关纹波后通过变压器串联在电网中，以达到稳定负载端电压、改善电能质量的目的。

Protection of vertical and cross direction is proposed. The principle and installation of differential protection and directional over-current protection which applied to ringlike type power network is presented.

船舶电力系统的各种型式的电网均要设置相应的保护装置，以便在电网发生各种故障时保护装置能选择性地动作将故障切除并

Through seriate and standard steel tower construction equipment and technology to improve it into advanced level in the world.

通过电网建设的发展，陆续形成革新化、系列化、标准化的组塔施工技术、施工装备，对全面提升我国电网建设领域施工达到国际先进水平具有重要意义。

This paper proposes a novel current control stratege to avoid this unstable. The grid current feedback is used controlled the power factor expediently, and a second differential link of grid current is designed to stabilize the system.

本文采用了一种新型的电流内环控制策略，该策略采取了电网侧电流反馈控制，能够方便的控制功率因数，在电流内环引入了电网电流二次微分来解决不稳定的问题。

Based on two kinds of control strategies of VSR under unbalanced grid condition,the introduction of a new VSR control strategy featuring undamped -oscillation that simplifies the controller structure and effectively improves VSR"s performance under unbalanced grid condition.· A systematic description of the state switching in trilogic PWM signal generation of three-phase CSR by using the conversion between bilogic and trilogic switching functions.· Referenced to the CSR"s trilogic PWM signal generation, an approach to achieve low-stress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss.

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；·通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；·结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

Referenced to the CSR's trilogic PWM signal generation, an approach to achieve lowstress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss. With the background of and well instanced by the Xinjiang Autonomous Region's Key SciTech Project"Solar Photovoltaic grid-connected inverter", the dissertation work implemented the new approach of a grid-connected PV inverter that was of single-phase VSR topology and with MPPT .

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。