Mitigation of voltage collapse through active dynamic buffers

Power electronics continues to grow as an element of electrical loads. Most such loads, including motor drives, computer power supplies, and compact fluorescent lighting, serve to 'isolate' the load dynamics from the utility grid. The unfortunate effect is that these loads enforce local constant power behaviour. This tends to destabilise the supply system, resulting in voltage collapse. In this work, the power buffering technique is examined to mitigate the effects of constant power loads. A power buffer is a device that enforces dynamic isolation to bestow beneficial dynamic characteristics upon the grid. A review of constant-power load dynamics and weak power systems is presented. Through simulations, the generalised power buffer concept is shown to stabilise several examples of power systems. Various techniques and topologies for power buffers are then covered and related to the voltage collapse problem, including critical control methods and parameters. Finally, three experiments are presented that demonstrate the stabilising effects of buffers.