ABSTRACT Two static equivalent methods are used to acquire equivalent parameter of power systems in this paper. These two methods combine feature and requirement of power systems and use the base-case system information and Thevenin equivalent theory for analyzing the voltage stability problem. The Q-V, P-V, P-Q curves and the minimum singular value, which has distinctive physical meaning and requires less computation work compared with the margin methods expressed by previous singular value, can be quickly got by these two methods respectively.

The Voltage/Var optimization power flow is calculated by the method of SQP (successive quadratic programming method), with regarding the minimum of transmission line losses as the objective functions, the reactive power flow equations as equality constrains and a set of voltage and control variables as inequality constrains. Deciding objective functions and constrains equations, the angle of voltage is not considered as constant but active power of transmission lines was considered as constant. In this paper, formulas of objective function, equality constrains and inequality constrains were deduced by constant active power. The demand on selecting initial values of iteration of this method is not strict. The results of reactive power optimization of Ward & Hale 6, IEEE 14 and IEEE30 bus systems show that this method had stable convergence.

将新兴的发电技术（风力发电、燃料电池发电）及新型储能技术（制氢储能、超导储能装置）引入传统的电力变电站，提出了不间断电力变电站的概念，使变电站的功率输出平滑、稳定、不中断。从分布式电源的通用接口模型出发，介绍了不间断电力变电站的模型，分析了其功率协调的机理。介绍了多代理技术的概念、代理的层次结构和代理间的交互策略，基于此构建了不间断电力变电站多代理协调控制系统，并展望了今后研究工作的方向。

本文研究了具有可控串联补偿功能的故障限流器（FCL）对改善电力系统暂态稳定性的作用，提出了一种基于模糊逻辑控制理论的故障限流器的稳定控制器。通过数字仿真验证了其对改善电力系统暂态稳定性的有效性和鲁棒性。

The additional controller in HVDC system can improve the power system stability. According to multi-infeed HVDC transmission system, this paper design the additional controller of HVDC system with the nonlinear control theory. The control law which we get consider the influence of two additional controls of DC system. It can improve the system stability to a great extent. The simulation results also testify the validity of it.