Based on differential geometric theory , a novel nonlinear modulation strategy for multi - iii infeed hvdc systems to enhance the transient stability of ac system in the presence of large disturbances is presented in this paper 针对大扰动情形，提出了一种用于改善多机交直流混合电力系统(有多条直流线路落点于其中)暂态稳定性的非线性调制策略。
The optimal - aim strategy ( oas ) is used to decide the controller ' s input variables , i . e . the modulated active and reactive power which can be determined according to the practical operating conditions of ac system and operating states of dc system 该方法利用最优目标策略（ optimal aimstrategy ，简记为oas八来得出有功功率的调制量，它是系统状态的解析函数。
Ac servo system has advantage over dc servo system , so study on ac system behavior has important sense . servo - control technology is one of the most import part of mechtronics , which is widely used on the automatic equipments 近年来，随着永磁材料性能的不断提高和完善，以及永磁电机研究开发经验的逐步成熟，永磁电机在国防、工农业生产和日常生活等方面获得了越来越广泛的应用。
This dissertation proposes a new approach to nonlinear active and reactive power modulation control design for multi - infeed hvdc systems , which realizes the emergency power support to ac system in the presence of large disturbances occurred in ac system 将己有的基于线性方法的有功及无功调制策略由单馈入直流输电系统推广至多馈入直流输电系统，并提出一种非线性的有功及无功调制方法。
Through the testing , the parameters of the two controllers are determined . the simulating results under faulty conditions show that the proposed controllers are effective for improving system transient stability and they make the hvdc system can operate with very weak receiving end ac system 在故障条件下的仿真结果表明，上述两种控制器均能有效地提高系统的暂态稳定性，而且能使系统稳定运行在受端为极弱交流系统的条件下。
It is concluded that the primeval design of hv ' ac system decide that the building noise environment is good or bad . as to say how to resolve the six sides problems : machine noise , machine vibration , fan noise , duct noise , draft noise and cross - talk noise 我们认为：建筑(使用hvac系统)声环境的好坏取决于hvac系统初期的设计，也就是如何解决好机械噪声、机械振动、风机噪声、管路噪声、气流噪声以及管路交互传递噪声这六方面的问题。
This dissertation focuses on the application of the fast controllability of hvdc systems to realize emergency power support to its connected ac system in the presence of large disturbances occurred in ac system , and more emphasis is given to the control strategies concerned with multi - infeed hvdc systems 利用直流输电系统的快速可控性，实现对交流输电系统的紧急功率支援，其本质就是研究在大扰动发生后应对直流系统采取何种控制策略。
I . e . strong coupling critical admittance and weak coupling critical admittance that affect the occurring conditions and types of commutation failures in multi - infeed hvdc system , are defined in this paper . factors which has great influence on the above two parameters , such as ac system strength 针对一个典型的多馈入直流输电系统，首次定义了影响多馈入直流输电系统中换相失败及其发生类型的两个重要参数，即强耦合临界导纳和弱耦合临界导纳。
For new structure , it is recommended to install the main and branch circulation pipes of water source & heat pump ac system first and leave its combination collocation for the decoration time according to the practical needs ; and it is more convenient for rebuilt project to adopt the water source & heat pump system and there is no need for the user to worry about establishing the cooling machine room 新建建筑可先安装水源热泵空调循环水管的主管和支管，机组可在用户装修时按实际需要配置，改建工程采用水源热泵系统则更为方便，可以省去用户为建制冷机房增添的烦恼。
Technologies , including loading balance in distributed system , distributed transaction and oriented object methods , which discussed in this thesis , have been introduced in the designing and implementation of acs system . this thesis finish the following working : we analyze the theory of load balancing and provide a load balancing model . a load balancing agrithm based on overall expected delay routing is implemented in acs . the experiment results shows that the average response time of job and the system resource utilization can be optimized in acs , distributed transaction is designed and implemented for the roaming file ' s processing , two phase commit proctol is used , which can ensure the atomic of distributed transaction commit , recover the exception quickly and improve the system ’ s reliability 应用控制系统acs ( applicationcontrolsystem )是针对中国移动漫游清算系统而开发的面向对象的分布式中间件产品,论文讨论了负载均衡、分布式事务、面向对象技术并介绍其在acs中的设计与实现,主要完成了以下的工作:分析了负载均衡的原理,提出了一种分布式动态负载均衡模型,在acs系统中成功实现了总体最小期望等待时间任务分配的动态负载均衡算法,实验证明这种算法缩短了作业的平均响应时间,提高了系统的资源利用率。
