MULTIPORT FREQUENCY-DEPENDENT NETWORK EQUIVALENTS FOR THE EMTP

A method is developed to reduce large power systems to single and multi-port frequency dependent equivalents. These equivalents consist of simple RLC modules that faithfully reproduce the frequency characteristics of the network. The method is implemented in the EMTP and has been extensively tested at Ontario Hydro. The implementation involves a pre-processor program to generate the model: the Frequency Dependent Equivalent (FDNE), and a EMTP time step loop module to calculate the transient response. The use of the FDNE results in major reductions in computer time and is especially beneficial for multi-case statistical EMTP studies. An example showing the accuracy and efficiency of the FDNE when used to reduce a large 500 kV network is presented.