Stability Analysis of Local Control Interactions in Active Distribution Networks

The evolution towards active distribution networks requires network operators to guarantee the stability of interactions between the various active devices to be deployed. This task is particularly challenging when devices include a combination of voltage and power flow controllers, such as Soft Open Points. This paper proposes a linear state-space model of the slow interactions between active devices to support operators in avoiding oscillatory and unstable system responses. Control modes of local control devices are modelled as droop-based equations and the corresponding interactions captured by the Jacobian of the distribution network, this way enabling standard linear state space-based analysis procedures. The application of the linear model is illustrated, determining the regions of stability predicted by the model and then simulating the non-linear response of the controllers at the frontiers of these regions to validate the model’s ability to identify stable regions.