ATP Comparison of transmission line models.pdfVIP

Alternative Transients Program - Comparison of transmission line models Orlando P. Hevia Gorostiaga 1483 Argentina 3000 Santa Fe Argentina email: heviaop@.ar 1. Introduction. The ATP allows to model transmission lines on different ways. The limitations of a simple model may produce useless simulations. Although a complex model may produce a better model representation, the accuracy of the result will depend on the event that it is wanted to simulate. In the following section a description of the available models is given, after that several simulation examples are presented to compare the models. These examples are: 1) Open-ended line connection 2) Three phase short circuit 3) Single phase to ground short circuit 4) Open-ended line disconnection. Comparison of the steady state solution, aerial and ground mode values, and the response of circuits with trapped charges will be given. 2. Available models. The available models in the ATP are: 1) PI circuit 2) Constant distributed parameter model (or K. C. Lee model) 3) Frequency dependent models based on the modal decomposition a)SEMLYEN SETUP b)JMARTI SETUP 4) TAKU NODA SETUP model. 2.1 PI Circuits The PI circuit is a discrete approximation to the constant distributed parameter model. Line models based on PI circuits were used as a first solution for transient studies either using the ATP program or Transient Network Analyzers. The PI circuit is not generally the best model for transient studies. The solution of the simulations using the distributed parameter model is faster and commonly gives more accurate results. The cascade connection of PI circuits can be useful for untransposed lines since it is not necessary to consider approximations of the phase to mode transformation matrix. By default, lines with frequency dependent parameter elements can not be represented by PI circuits. Moreover, spurious oscillations generated by lumped parameter elements must be accepted. However, resistances connected in parallel with