Using RSCAD's Simplified Inverter Components to Model Smart Inverters in Power Systems

Abstract

There is growing interest in Smart Inverters (SIs) thanks to their capabilities of providing auxiliary support. Power companies are interested in deploying them in their networks to get necessary frequency and voltage support at times of need. However, these inverters dynamically exchange real and reactive power with the grid and try to change operating point of the system. This dynamic behavior at the distribution level of the power systems may create unprecedented problems. In order to test their impact on the network, hardware-in-the-Ioop (HIL) testing is preferred. HIL tests give higher fidelity than simulation-only studies and can model real power networks to study a particular phenomenon. With a combination of real SI hardware and power system modeled in software, different operating modes and their impact on the system can be investigated thoroughly. It is a real challenge to model several SIs in a distribution network as they require small time step modeling which limits computing capacity of real-time simulation platforms such as RTDS. In order to circumvent this issue, simplified inverter models in RSCAD are utilized to model SI functions such as Volt-Var or Power Factor control. With this approach, individual switches within an inverter are not modeled and phenomena that are resulting from rapid switching, such as harmonics, are not taken into account. For studies that focus on the power flow control or voltage support, this trade off is acceptable as many SIs can be easily implemented within a network.