Impact of increasing amounts of distributed generation on transient behavior of the distribution system

Abstract

To investigate the impact of increasing penetration levels of PV in a distribution feeder under different environmental conditions was proposed in this research. A NEETRAC member Feeder was imported from OpenDSS into the DIgSILENT PowerFactory software, and its voltage transient stability was investigated under different environmental conditions. ANSI 105% voltage threshold violations were observed in the feeder when all PV inverters were controlled in Unity Power Factor mode. To mitigate this violation, a Volt-Var control mode with ± 2 % deadband, 0.95 pu lower limit, and 1.05 pu upper limit was used. This control scheme mitigated the ANSI 105% voltage violations on NEETRAC member Feeder during different environmental conditions. The IEEE 13 Node Test Feeder was modeled in Matlab/Simulink software. PV systems with a total penetration level of 120 % were installed at different nodes of the feeder, and frequency transient stability of the system was investigated. It was observed that higher penetration of PVs in the feeder adversely affect the frequency stability of the system during sudden load changes. To mitigate this frequency instability, a battery management system with modified Frequency-Watt function was developed and installed at the substation of the feeder. This battery management system emulated inertia and provided the necessary real power to stabilize the frequency of the system.