Integral Controllability-Based Design of Voltage and Active Power PI Regulators for Grid-Connected DG

This paper presents the design of PI regulators for voltage and active power control in grid-connected Active Dis-tribution Networks (ADNs) with Distributed Generators (DGs) based on Renewable Energy Sources (RESs) and interfaced to the network by a Voltage Source Converter (VSC). For each DG two PI regulators control the dq current's components injected into the network by the VSC. The fulfilment of the integral controllability condition, which does not involve the parameters to design, guarantees closed-loop stability. Subsequently, a constrained nonlinear optimization problem is solved to find the regulators parameters. Variations of the operating conditions of the ADN are represented by the output multiplicative model of the uncertainty. Afterwards, the use of the real stability radius allows to find the largest perturbation which makes the integral controllability condition not satisfied. Finally, a Low Voltage (LV) 36-nodes ADN equipped with 9 DGs, is used to verify the effectiveness of the proposed design.