Induction Motor Load Dynamics: Impact on Voltage Recovery Phenomena

Abstract

Abstract-This paper addresses the impact of load dynamics, and in particular induction motor loads, on voltage recovery after disturbances. The paper proposes a methodology that is based on load flow techniques with advanced modeling capabilities, augmented by a simplified induction motor dynamic model. The objective is to realistically capture the dynamic characteristics of voltage recovery phenomena, avoiding, however, the full scale transient simulation. The approach uses the quadratized power flow model with explicit induction motor representation. The paper describes the modeling approach and the overall methodology for evaluating the load dynamics on voltage recovery. Preliminary results of the application of the method on a simple power system with load dynamics are also included in the paper.

Role of Induction Motors in Voltage Instability and Coordinated Reactive Power Planning

“…While trying to recover, if the voltage drops to a very low point for a sustained duration due to system's inability to provide reactive support, some motors may stall. Such drastic stalling of motor further exacerbates the conditions by increasing the reactive power requirements quickly, and the rate of voltage decline can accelerate catastrophically [6,7,16]. Massive loss of load and possibly area instability and voltage collapse may follow.…”

“…It is not just the amount of reactive support, but also the quality and placement of reactive support that matters. For instance, it is found that due to the presence of electric loads that are predominantly induction motors the voltage recovery of the system following a severe disturbance is delayed due to lack of fast responding reactive support, thereby threatening to have secondary effects such as undesirable operation of protective relays, electric load disruption, and motor stalling [6,7]. While a number of techniques have been developed in the past to address the problems of voltage instability [8], there has been little work towards a long term reactive power (VAR) planning (RPP) tool that addresses both steady state as well as dynamic stability issues.…”

Distributed load interruption and shedding against voltage delayed recovery or instability

“…FIDVR is caused mainly by induction motors re-accelerating after a severe voltage drop [2,3]. This results in an excessive draw of current from the grid which depresses the voltage even more.…”

Modeling and Dynamic Analysis of STATCOM for Short-Term Voltage Stability Improvement using EMTP/RV

“…Although voltage stability involves dynamics, power flow based static analysis methods are often useful for rapid, approximated analysis. However these static methods, so called steady-stated analysis, cannot capture the dynamic nature of the voltage collapse phenomena [7]. Time-based simulations play a critical role in tracing the mechanism of this type of voltage instability [8].…”