Voltage stability and voltage recovery: load dynamics and dynamic VAr sources

Abstract

Voltage instability may occur from a variety of phenomena. Two of the most frequent are: (a) voltage recovery following typical faults on a power system and (b) voltage collapse during transient swings of the power system. We propose approaches to deal with these phenomena consisting of identifying the phenomena involved and proper response of control devices in the system such as dynamic VAR sources to mitigate the problem. Most of the times the phenomena are tolerable assuming that there are no secondary responses such as tripping of motors, switching of reactors etc. that tend to aggravate the problem. We also propose tools for reliable simulation of the phenomena involved. Specifically, a modeling approach is proposed, coined the time continuation method, that combines the efficiency of power flow techniques and capabilities of transient stability models. The proposed methodology is based on a quadratic model of the electric power system, including generators, voltage regulators and dynamic loads consisting mainly of induction motors. It is shown that the proposed method and model explains recent observed voltage stability and voltage recovery phenomena. Numerical experiments with visualizations are presented for the purpose of quantifying the phenomena and identifying the major parameters affecting these phenomena. It is shown that proper combinations of static and dynamic reactive power sources can alleviate the risk of voltage instability. Finally, the paper proposes a methodology for selecting the location and size of a mix of static and dynamic VAR resources for the purpose of alleviating the risk of voltage instability and slow voltage recovery.

Data-Driven Short-Term Voltage Stability Assessment Using Convolutional Neural Networks Considering Data Anomalies and Localization

“…Emergency control strategies can be divided into planning stage remedies and operational stage real-time post fault clearance remedial actions [2]. Planning stage remedies rely on deploying dynamic VAR devices like STATCOM and SVC to strengthen reactive power support in response to delayed voltage recovery [3]. During post-fault real-time remedies, the operational stage relies on taking real-time actions like Under-voltage load shedding (UVLS) based on voltage recovery response [4], [5].…”

A Reactive Power Compensation Strategy for Voltage Stability Challenges in the Korean Power System with Dynamic Loads

“…In [16,17], a trajectory sensitivity analysis method is proposed to mitigate voltage instability using dynamic reactive power resources. References [18][19][20][21] used sensitivity as a performance measure for VAR sources to satisfy the requirements of voltage stability margin and transient voltage dip. In [22], a sensitivity index is applied to determine the most influential locations of dynamic VAR support under certain contingencies.…”

A new approach to optimization of dynamic reactive power sources addressing FIDVR issues

“…Mid-term time-domain simulation is performed for refining the solution. In [4], a technique called "the time continuation method" is applied to find the locations and amounts of dynamic var sources, coupling with a quadratic model of the electric power system, including generators, voltage regulators, and induction motors. In [5] and [6], the dynamic var allocation problem is formulated as a mixed integer nonlinear programing problem.…”