Design and evaluation of a distributed control architecture over switched Ethernet in active filters

Abstract: The area of power quality has received more and more attention during the last decade. Poor power quality is a growing problem, especially for the industry because it has a negative effect on production efficiency, power consumption and equipment life-span. Active filters are one of the more widespread solutions to these problems. An active filter is often sized and installed to compensate a specific load, based on a preceding power quality measurement. Often one system is not enough and multiple parallel systems must be used. This thesis investigates if it is possible to design a distributed control system where a number of filters work together and communicate using a switched Ethernet network. Such a distributed system can offer advantages such as better coordination and simplified configuration and operation. In the resulting distributed system the control tasks are split into two groups, power quality controllers and hardware controllers. The power quality controllers are executed by a master control computer and the resulting setpoint is distributed through the network to a number of slaves. The distributed system has been tested both through simulations and in a real-world implementation. Based on these tests it can be concluded that the distributed system works and that its performance is only marginally affected compared to the original system.