The Influence of Motor Low Voltage Trip on under-Frequency Load Shedding in the Electric Network of Refinery Enterprise

A simple frequency response model is generally used in UFLS (under-frequency load shedding) design, without considering the impact of voltage on the frequency. In fact, in the case of large active and reactive shortage power, the system will suffer from the low voltage problem by the emergence of low frequency, which easily leads a large number of motors tripping due to low voltage protection trip in the UFLS process. The influence on UFLS is compared and problems needed to solve are put forward.