A Source Identification Method of Commutation Voltage Notch Oscillation Source

Abstract

An identification of source is important for countermeasure of transient oscillation problem. The paper proposes a new identification method in primary distribution system. For example, a convertor, which is a source, makes a line voltage notch at commutation time and, then, the natural oscillation of distribution system is occurred. Because the natural oscillation frequency is determined by the location of convertor in distribution system, the frequency is a very important indicator of identification. The features of new method are as follows:
(1) Using the eigen values and eigen vectors of system state differential equation, the correlation matrix of each natural oscillation is introduced as the indicator of identification. Since the value of matrix element shows the correlation intensity between nodes, the matrix of measured natural frequency is useful for identification of commutation voltage notch oscillation source.
(2) Since the components of particular Fourier order are intensified with the influence of convertor operation mode, it is difficult to determine the natural frequency. To avoid this problem, an quasi-transient data are introduced with modification of measured data and the determination of natural frequency can be executed easily.
Then, the new method is eximined by field test, and shows that it is very effective for identification of commutation voltage notch oscillation source.