Abstract

Short-term voltage instability has a sensational effect once it occurs with massive loss of load, possibly area instability, and voltage collapse. This paper analyzes the short-term voltage instability caused by induction motor from the viewpoint of active and reactive power joint balancing. The analysis method is based on (1) the reactive power balancing between system supply and induction motor demand, and (2) the active power balancing between air-gap power and mechanical power, which is expressed by the region of rotor acceleration and deceleration in the Q-V plane. With the region of rotor acceleration and deceleration in the Q-V plane and the reactive power balancing, the movement direction of the operating point can be visually observed in the Q-V plane, thereby achieving a clear comprehension of physical properties behind the short-term voltage instability phenomenon. Furthermore, the instability mechanisms of two kinds of grid-connected induction motor operation conditions after a large disturbance are discussed to explain the basic theory of the analysis method and to provide examples of its application. Time-domain simulations are presented for a single-load infinite-bus system to validate the analyses.

Highlights

  • Short–term voltage instability is caused by fast-acting load components that tend to restore power consumption in the order of several seconds after a voltage drop induced by a contingency [1]

  • In other power is larger than the supplied reactive power, the unbalanced reactive power drives a decrease in where Pe * represents the air-gap power that is the numeric equivalent of the Induction motor (IM)-demanded active terminal voltage magnitude

  • If the fault is cleared at point A5, as shown in Figure 9b, similar to the analysis shown in above, If the fault is cleared at point

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Summary

Introduction

Short–term voltage instability is caused by fast-acting load components that tend to restore power consumption in the order of several seconds after a voltage drop induced by a contingency [1]. Motivated by [7], in which the authors propose an analytical method using the transient P-V curves of the targeted load bus, an improved analytical method for short-term voltage stability applying to disperse power generation is proposed [8,9,10]. In these literatures, active power balance affected by voltage determines the motion state of the rotor speed, and determines the stability boundary.

Active and Reactive Power Joint Balancing
Active
Acceleration
Acceleration in the the Q-V
Section 2.1 and
Determination Method Based on Active and Reactive Power Joint Balancing
Constant Slip Curve in the Q-V Plane in Transient
Constant
Itwith reflects the change of slipvoltage on the
IM Stalling after a Large Disturbance
Abnormally Low Voltage Analysis
11. Since theQrotor has the terminal rotor speed cannot be abruptly
Critical
13. Critical
Conclusions

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