Numerical Oscillation Prevention for PV Inverter Controllers in Quasi-Steady-State Simulators

Droop-based inverter control methods are popular for preventing overvoltage in low voltage networks with high installations of photovoltaic (PV) solar. Quasi-steady-state simulators (QSTS) can be used to reduce the computational burden of conducting long-term techno-economic analyses of such PV inverter controllers. If dynamic models for droop-based controllers are directly implemented in QSTS, numerical oscillation occurs and the controllers fail to converge to their steady-state operation. In this paper, a power network sensitivity-based algorithm is proposed for preventing numerical oscillation while implementing active and reactive droop-based PV inverter controllers in QSTS (i.e., GridLAB-D). Convergence of the sensitivity-based algorithm is verified using a typical radial distribution feeder for three droop-based PV inverter controllers. The proposed algorithm limits the maximum error in voltage below 0.5% for all controllers compared to the dynamic simulation in PSCAD.