System Strength Enhancement of Emerging Distribution Networks Using Robust WAMPAC Schemes

This paper presents assessment of system strength of an emerging distribution system with high penetration of photovoltaic (PV) generators. Existence of low damped oscillatory modes due to control system interaction is considered as system strength challenges of emerging networks. Such low damped oscillatory modes due to interactions among PV generators and controllers could lead to instability of the distribution system. This paper shows that PV generators can be dominant on the unstable oscillatory modes, which can also be sensitive to generator parameters. The paper also presents an approach to design a robust damping controller to enhance damping of unstable or critical mode. The simulations and results are carried out in a 43 bus distribution system. The results demonstrate that low damped oscillatory modes can be present in the distribution system and can be sensitive to the PV generator parameters. A Wide Area Monitoring Protection And Control (WAMPAC) based robust control scheme can be designed to enhance damping of critical mode to improve overall system strength.