Real-Time Reduced Model of Active Distribution Networks for Grid Support Applications

Seeking to reduce the computational effort to model the intrinsically complex active distribution networks (ADNs), this article proposes a new realistic approach to develop a real-time reduced steady-state model of an ADN using synchrophasor measurements. Such models facilitate much needed co-simulation of the bulk power system (BPS) and multiple ADNs for grid support applications. With the advent of distribution-level phasor measurement units (D-PMUs), the synchrophasor data are employed to derive the reduced model parameters in real-time and track the time-varying ADN operating point. The proposed approach develops a general three-phase four-wire reduced model which can replace any arbitrary feeder configuration confined within D-PMUs. The explicit modelling of neutral-wire under different neutral-grounding conditions results in accurate representation of any unbalanced and complex feeder segment, containing transformers, distributed generators, loads and n-phase laterals. Further, the reduced model is modified to account for embedded distributed generation, which is useful for effective estimation of grid support capability at the transmission-distribution interface. The proposed reduced model has been extensively validated on the highly unbalanced IEEE-13 bus feeder system for various test cases, including high penetration of locally-controlled photovoltaic inverters. DIgSILENT PowerFactory MATLAB co-simulation has been used as the platform to establish the model accuracy.