Increasing power supply reliability in a large chemical plant taking system dynamics into account

The dynamic behaviour of in-plant generators and of induction motor loads is compared before and after extension of the power system based on the example of a large chemical plant. The stability behaviour of the generators and motors with respect to active power and reactive power is taken into consideration in dimensioning the decoupling criteria for splitting the power system into isolated power subsystems when severe power system faults occur. The active and reactive power dynamic characteristics prior to and subsequent to decoupling are primarily responsible for the decoupling criteria and the tripping times for the tie circuit breakers. The dynamic behaviour of the plant on power system faults is tested by means of simulation. Effectiveness of the selected measures can thus be depicted and compared. Changes in dynamic behaviour subsequent to extension of the power system are taken into account in the design of the power system and of the protection measures