Influence of Regulation of OLTC Transformation Ratio on Voltage Stability

The self-regulation of on-load tap changer (OLTC) transformation ratio is an important factor causing voltage instability. This paper introduces OLTC simulation models and their characteristics. Based on the sensitivity information, this paper deduces the voltage-regulating effect of OLTC in different load models with usage of the analytic method. The voltage-regulating effect of OLTC is very complicated. For different system operating conditions, different load types and different transformation ratios, the voltage-regulating effect may be different. At last, this paper summarizes the current OLTC control strategies to prevent voltage collapse.