Open loop response characterisation of an aluminium smelting plant for short time interval feeding

An Aluminium smelter is one of the peculiar loads, which typically represents a series of electrolytic cells supplied by a multipulse rectifier system. From the perspective of modelling a smelting plant for load modelling purposes, the multipulse configurations and its connection to HV networks and control aspects of load current must be considered. This paper presents the results of preliminary simulation work carried out covering the open loop behaviour of a smelter load under some varying system conditions. A typical smelting plant with a twelve pulse rectifier system has been modelled in PSCAD^reg/EMTDC^copy. The plant is connected to the AC network through a 220 kV/110 kV transformer with tap changing facilities to maintain the DC voltage. The saturable reactors are also included on AC side in order to control the load current of the smelter. Investigations have been carried out to characterise the behaviour of the smelter load under varying feeding conditions and determine the voltage and frequency dependency of the smelter load under small disturbances.