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Several heuristic procedures to estimate the rotor position of interior permanent magnet synchronous motors via signal injection have been reported in the applications literature, and are widely used in practice. These methods, based on the use linear time invariant high-pass/low-pass filters, are instrumental for sensorless controllers. To the best of our knowledge, no theoretical analysis has been carried out for them. The objectives of this note, are (i) to invoke some recent work on the application of averaging techniques for injectionbased observer design to develop a theoretical framework to analyze the sensorless methods, and (ii) to propose a new method that, on one hand, ensures an improved accuracy and, on the other hand, can be related with the current filtering technique. An additional advantage of the new method is that it relies on the use of linear operators, implementable with simple computations. The effectiveness of the proposed scheme is assessed by experiments. 

Abstract—We describe a method for simultaneously identifying and reducing dynamic power systems models in the form of differential-algebraic equations. Often, these models are large and complex, containing more parameters than can be identified from the available system measurements. We demonstrate our method on transient stability models, using the IEEE 14-bus test system. Our approach uses techniques of information geometry to remove unidentifiable parameters from the model. We examine the case of a networked system with 58 parameters using full observations throughout the network. We show that greater reduction can be achieved when only partial observations are available, including reduction of the network itself. Index Terms—Parameter Estimation, Reduced Order Systems, System Identification. 

The paper describes the phenomenon of electronic power waves in large networks of inverters. These waves have similarities with electromechanical waves that have been observed in actual electric power systems, and also have significant differences, including dependence on control tuning of inverters and on operating point. Electronic power waves are significantly faster than their electromechanical counterpart, but way below the speed of light. Analytical models are presented and illustrated by computer simulations. They provide a basis for further study of spatial phenomena in emerging inverter-rich power systems, made possible by new generations of sensors (such as phasor measurement units) equipped with very accurate time stamps.