Impact of the Aggregate Response of Distributed Energy Resources on Power System Dynamics

This paper addresses a current concern of the Irish transmission system operator, namely, the impact of aggregated distributed energy resources (DERs) on the dynamic behavior of transmission systems. The aggregation of DERs is done through the virtual power plant (VPP) concept. The paper considers two approaches to operate the VPPs. First, a mixed-integer linear programming (MILP) that optimally schedules the DERs that compose the VPP is presented. The MILP is embedded into a time domain simulator (TDS) by means of co-simulation framework in order to study its impact on the dynamic response of the system. Then, an automatic generation control (AGC) approach is proposed to coordinate the DERs included in the VPP. The case study based on the IEEE 39-bus system serves to illustrate the features and dynamic behaviour of the proposed approaches.