Short and Long-Term Dynamic Voltage Instability

This paper presents a novel approach to capture the development of dynamic voltage instability caused by the dynamics of different power system devices, such as loads, generators, automatic voltage regulators (AVR), overexcitation limiters (OXL), power system stabilizers (PSS), and onload tap changing (OLTC) transformers using an accurate time-domain analysis. A small power system model is presented which allows one to analyse combinations of these effects, showing how different major forms of long-term and short-term dynamic voltage instability occur. Effects of line tripping, sudden change of load, and fault clearing time on dynamic voltage instability will also be discussed. Finally, advantages of the dynamic analysis over the static analysis will be investigated.