Caledonian Paper DVR-the utility perspective

ScottishPower have been actively monitoring the effects of power quality problems on customer processes for some years. Although all customers are affected differently, there are some general issues that can be applied to all. Production equipment is not normally compatible with distribution networks and will fail to operate as a result of disturbances on the incoming power supply. Electricity utilities take every possible step to eradicate faults but their extensive networks are prone to damage and the resultant voltage dip will propagate over a large area of the interconnected network. Electricity distribution utilities are caught in the middle of this power quality dilemma. Customers are the victims of this incompatibility and, rightly, are upset when their production output is affected by something outwith their control. Utilities are improving voltage dips by introducing electronic protection relays and gas/vacuum switchgear. Producing a fault-free network is not practical but fast clearance of system faults greatly reduces the associated voltage dips. Unfortunately customers perceive that power quality is deteriorating. Utilities believe this is a result of customers increasingly using unprotected microprocessor-based equipment. The utility needs to demonstrate that the power quality at a particular site cannot be improved without major investment in infrastructure. This poses regulatory problems about site-specific investments