EMTP modelling of control and power electronic devices

The quality of the electric power delivered to customers by utilities may not be acceptable for some types of sensitive loads, which are typically power electronicsand computer-based loads, particularly in the control of industrial processes. There are cases where the increasing use of power electronics to enhance process eÆciency and controllability creates power quality problems. The growing application of shunt capacitors for voltage support, power factor correction, and system loss reduction, as well as the use of series capacitors ( xed or controlled, for line reactance compensation) will increase the potential risk of transient disturbance ampli cations and potential electrical and mechanical resonances in the presence of more and more power electronic devices, and of steam and gas turbines in distributed and co-generation power plants. As the natural order of the system grows, so does its ability to oscillate more! At the same time, new power electronic devices also o er the means for adequate \power conditioning", to meet the special requirements of electric power quality in a system. To evaluate the promising solutions o ered with the introduction of more and more power electronic devices in transmission and distribution systems, such as FACTS (Flexible AC Transmission Systems) Controllers and Custom Power Controllers, as well as to analyze their interaction and impact on either the load or the network side, computer programs based on the EMTP (Electromagnetic Transients Program) are becoming more useful. The development of new EMTP-based models for representation of controls and power electronic devices has been the main subject of this Ph.D. thesis project. Its main contributions are summarized as follows: development of a \simultaneous solution for linear and nonlinear control and electric power system equations" (SSCPS) in EMTP-based programs, through the compensation method and the Newton-Raphson iterative algorithm. This solution method eliminates not only the one time step delay problem at the interface between the solution of power and control circuits, but also all the internal delays, which may exist in methods based on the transient analysis of control systems (TACS) since 1977. A \circuit approach" was proposed in this thesis, as an innovative alternative to the solution presented by A. E. A. Ara ujo in 1993; experimental implementation in MicroTran R (the UBC version of the EMTP), based on SSCPS, of a \simultaneous solution" for: linear and nonlinear current and voltage dependent sources; independent current and voltage sources, which can also be connected between two ungrounded nodes; hard and soft limiters; transfer functions; mathematical and transcendental FORTRAN functions; special control devices and some digital logic gates; transformation of variables (such as the abc to 0 transformation