Investigation of Sub-Cycle Overvoltages Experienced by Inverter-Based Resource (IBR) Plants Due to System Disturbances

IEEE Std 2800-2022 marks a major step forward in defining minimum technical requirements for connecting inverter-based resources (IBRs) to the Bulk Power System (BPS). However, as the standard gains wider adoption and real-world implementation progresses, stakeholders (including IBR owners, grid operators, Original Equipment Manufacturers (OEMs), and technical working groups) have noted key observations and limitations related to its transient overvoltage (TrOV) ride-through requirements in clause 7.2.3. Under the current specification, the IEEE Std 2800-2022 TrOV ride-through requirements specifies that IBR plants conform at the point of measurement (POM). Typically, there is no transient overvoltage protection applied at the POM. The transient overvoltage protection is generally applied at the IBR unit terminals. If the voltage transients at the POC is expected to be more than the transient overvoltage capability of the IBR unit, then proper application of surge protection within the plant may be necessary. This creates challenges in demonstrating conformance to TrOV ride-through requirements. To show conformance to TrOV ride-through requirements, it is important to understand how TrOV manifests at the IBR plant POM and at individual IBR unit terminals (POC) during various transmission grid disturbances or system events. This work examines how TrOV manifests at the plant point of measurement and at individual IBR unit terminals. Both non-aggregated and aggregated IBR plant models are considered, with key learnings guiding the choice of model for analysis. Additionally, it introduces several assessment approaches for TrOV conditions, leveraging electromagnetic transient (EMT) simulations to validate findings. Lastly, it highlights some of the gaps hindering the conformance to the TrOV ride-through requirements.