Impact of distributed generation units with power electronic converters on distribution network protection

An increasing number of distributed generation units (DG units) are connected to the distribution network. These generators affect the operation and coordination of the distribution network protection. The influence from DG units that are coupled to the network with a power electronic converter (PEC) is different from that of conventional DG units with an electrical machine directly coupled to the network. This contribution shows that PEC-based DG units can be controlled in such a way that the negative influence on the distribution network protection is limited. A decision tree and a flow-chart are presented that show how a PEC-based DG should respond to network faults. The flow-chart can be used in real time to bring the proper control algorithm in operation during a fault.