RESEARCH ON SERIES ACTIVE CAPACITANCE TO POWER SYSTEMS

(1)首席研究员A.Nabae利用极坐标提出了瞬时有功-无功电流和功率的新定义。基于新的定义，研究小组开发了一种新的三相电力系统串联有源电容，它能够补偿由系统阻抗引起的基波分量的谐波压降和相角延迟。对系统的动力学行为进行了理论分析，并进行了计算机仿真，得到了满意的结果。(2)为了建立最优控制算法，需要对包含旋转坐标变换的控制系统进行分析。然后，引入了一种新的适用于两输入两输出系统的复变传递函数，证明了复变传递函数分析方法在分析控制系统中的有效性。(3)电源频率总是在一定范围内波动的。-0.1 Hz，其检测方法是亟待解决的重要问题之一。该课题组建立了一种新的基波检测方法，采用旋转坐标变换，实现了基波频率的瞬时检测，为解决电力系统稳定问题和2个并联输电系统的潮流分担问题做出了贡献。

(1) The head investigator A.Nabae proposed a new definition of the Instantaneous Active-reactive Currents and Powers using polar coordinate. Based on the new definition, the research team has developed a new series active capacitance for three-phase power systems, which is able to compensate both harmonics voltage drop and phase angle delay of fundamental component caused by the system's impedance. The dynamic behavior was analyzed theoretically and satisfactory results have been obtained from computer simulations.(2) In order to establish a best control algorithm, it is required to analyze a control system including rotating coordinate transformation. Then, a new complex transfer function applicable to 2-input and 2-output system was introduced and it was shown that the complex transfer function analysis was effective in analyzing the control system.(3) Power source frequency fluctuates always within a range of (]SY.+-[)0.1Hz, and its detection method was one of the important problems to be solved. The project team has established a new detection method of the fundamental wave, in which rotating coordinate transformation is used and the fundamental frequency can be instantaneously detected.As the results of this research project, the series active capacitance will contribute to solve power system stability problem and power flow sharing problem of 2 parallel transmission systems.