A Novel Over-Current Protective Device Characteristic Developed by Eigensystem Realization Algorithm and Its Practical Applications

• Main Authors: Feng-Jih Wu, 吳峯日
• Other Authors: Chih-Ju Chou
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/8c42e7

博士 === 國立臺北科技大學 === 電機工程系所 === 101 === Accurate models of the characteristics of typical inverse-time overc-urrent (OC) protective devices play an important role in the protective coordination schemes in the sub-transmission and distribution systems. The first dissertation presents a novel approach to determine the OC protective device parameters. The approach is based on the Eigensystem Realization Algorithm (ERA) which generates a state-space model to fit the characteristics of OC protective devices. Instead of the conventional characteristic curves, the dynamic state-space model is a more accurate fit of the OC protective device characteristics. This dissertation describes the detail procedure of decomposing the characteristic curve into smooth components and oscillation components. For demonstrations, 27 characteristic curves are selected from both typical and non-typical OC protective devices for curve-fitting. The numbers of fitting components required are determined by the desired level of maximum absolute values of errors for the fitting equations. Furthermore, all fitting equations for the characteristics of OC protective devices can be replaced by one single equation representing a universal OC relay which can be used to solve the problems of over-current coordination and the like in the sub-transmission and distribution systems.