Shifted frequency analysis-EMTP multirate simulation of power systems

Abstract

This paper presents a novel hybrid multirate protocol to interface a Shifted Frequency Analysis (SFA) simulator and an Electromagnetic Transients (EMT) simulator. The proposed protocol is based on the Multi-Area Thévenin Equivalent conceptual framework and uses a second parallel simulation of the EMT simulator to track the imaginary part of the complex-valued solution from the SFA simulator. Having a Real-Part EMT simulation and an Imaginary-Part EMT simulation, running in parallel, maintains the analyticity and synchronicity of the SFA/EMT hybrid simulator and enables the use of large time steps in the SFA solution. This also allows the extraction of the fundamental frequency phasor of the EMT solution directly through the SFA transformation. The interfacing algorithm is demonstrated on the IEEE 39-bus system. The proposed protocol shows very good accuracy for capturing the electromechanical transients with the SFA simulator and an EMT-comparable accuracy with the EMT simulator. The results show the capability of the hybrid simulator to use significantly different solution steps in the SFA and EMT simulators, which results in considerable savings compared with an all-EMT solution. The proposed simulator would be very useful in conducting transient stability-type of studies when there is a need to model some devices with EMT accuracy.