A controlled power electronic converter can cause local instabilities when interacting with other dynamic subsystems in a power system. Oscillations at a certain frequency cannot, however, build up if the converter differential input admittance has a positive conductance (real part) at that frequency, since power is then dissipated. In this paper, input-admittance expressions for a voltage-source converter are derived. It is seen how the admittance can be shaped in order to get a positive real part in the desired frequency regions by adjusting the controller parameters.

Input-Admittance Calculation and Shaping for Controlled Voltage-Source Converters

The large-scale integration of power electronic-based systems poses new challenges to the stability and power quality of modern power grids. The wide timescale and frequency-coupling dynamics of electronic power converters tend to bring in harmonic instability in the form of resonances or abnormal harmonics in a wide frequency range. This paper provides a systematic analysis of harmonic stability in the future power-electronic-based power systems. The basic concept and phenomena of harmonic stability are elaborated first. It is pointed out that the harmonic stability is a breed of small-signal stability problems, featuring the waveform distortions at the frequencies above and below the fundamental frequency of the system. The linearized models of converters and system analysis methods are then discussed. It reveals that the linearized models of ac–dc converters can be generalized to the harmonic transfer function, which is mathematically derived from linear time-periodic system theory. Lastly, future challenges on the system modeling and analysis of harmonic stability in large-scale power electronic based power grids are summarized.

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Harmonic Stability in Power Electronic-Based Power Systems: Concept, Modeling, and Analysis

The interconnection stability of a grid-connected voltage-source converter (VSC) can be assessed by the passivity properties of the VSC input admittance. If critical grid resonances fall within regions where the input admittance acts passively, i.e., has nonnegative real part, then their destabilization is generally prevented. This paper presents an overview of passivity-based stability assessment, including techniques for space-vector modeling of VSCs whereby expressions for the input admittance can be derived. Design recommendations for minimizing the negative-real-part region are given as well.

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Passivity-Based Stability Assessment of Grid-Connected VSCs—An Overview

Since the publication of the original paper on power system stability definitions in 2004, the dynamic behavior of power systems has gradually changed due to the increasing penetration of converter interfaced generation technologies, loads, and transmission devices. In recognition of this change, a Task Force was established in 2016 to re-examine and extend, where appropriate, the classic definitions and classifications of the basic stability terms to incorporate the effects of fast-response power electronic devices. This paper based on an IEEE PES report summarizes the major results of the work of the Task Force and presents extended definitions and classification of power system stability.

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Definition and Classification of Power System Stability – Revisited & Extended

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Wind Power: Modelling and Impact on Power System Dynamics

This book provides an introduction to subsynchronous resonance in power systems and includes material on system modeling, system parameters, and system analysis.

Basant L. Agrawal

Papers

Subsynchronous resonance in power systems