A new method using relay macromodels for simulation of the transient response of distance relays.

摘要

This dissertation presents an improved method for analyzing the performance of distance relays under transient conditions through the use of sampled-data relay macromodels. A macromodel is a composite of independent mathematical models functionally equivalent to a physical distance relay. Distance relays, which use complex equations and are decision-making devices, have been difficult to model within the ElectroMagnetics Transients Program (EMTP) and other power system simulation programs. Until now power system engineers have had to estimate relay responses and response parameters such as time of response. The use of macromodels would permit closed-loop simulations of distance relays and would approximate actual relay performance.;The macromodel developed in this project is composed of four individual models or sections: the low-pass filter, analog-to-digital converter, phasor detector, and measuring unit. The modeling language is a version of the Transient Analysis of Control Systems (TACS) section of EMTP called Models. The first step of this project is the modeling of the measuring unit, which uses the mho relay measuring principle. Accepted industry relay testing practice was followed to verify the model of the measuring unit. The parameters of each section of the macromodel are set to simulate a specific commercial relay. Before the four sections are assembled into the macromodel, each section is tested under steady state conditions. The measuring unit is also tested under dynamic conditions. Performance of the entire macromodel is then verified under transient conditions by applying identical simulated power system faults to the macromodel and to a physical relay. Identical trip-no trip responses are obtained 100% of the times studied, with response times to faults varying by five to 18 milliseconds.;Once tested, the macromodel is used in a closed-loop simulation of a series compensated transmission system. Power system faults are simulated at transmission line locations that historically have caused relay mis-operations. Relay macromodel mis-operations are observed, and settings changed to produce correct relay operations. Correct relay responses are obtained in all cases, except when series capacitors are in operation on the protected line.