Virtual impedance concept for voltage angle-based operation in converter-dominated grids

With the increasing use of renewable energy sources in the electricity grid, the presence of synchronous generators is decreasing more and more until they are switched off. As a result, it is necessary to adapt power grid operation to the new framework. A perspective method for power grid operation is the power system operation with angle-based control. A special feature of power grid operation with angle-based control is that the provision of balancing power depends on the electrical distance to the location of the load change. Besides the typical droop control, the allocation of the balancing power among the voltage source converters can be influenced by the use of virtual impedance. In this paper, it is shown how the virtual impedance can affect the allocation of the balancing power among the VSCs in the case of a power system operation with angle-based control. A simplified control circuit is created and implemented in the IEEE 14-bus system.