The safety risk assessment and mitigation measures of the LV networks with embedded generators.

Abstract

Electricity industry liberalization across the world has seen a significant growth in the utilization of autonomous- and distributed power sources deployed at sub-transmission (132 - 33 kV) and reticulation levels (<33kV) in stand-alone or grid connection notations. With the electricity industry reform, an open access regime is a standard policy governing the transmission grid, and this provides for full competition at generation and distribution end of the delivery value chain. The National Electricity Regulator of South Africa (NERSA) is currently examining a roll out plan for a nation-wide rooftop photovoltaic (PV) system. Most of these roof top PV systems are expected to be connected on the low voltage (LV) networks (<1kV). The widespread deployment of such PV installations have associated risks to personnel and could pose challenges to system operations. Most utility field service engineers are not aware of the dangers posed by such installations. Dangers may include but are not limited to reverse power flow from installed PV systems should the anti-islanding protection fail after the loss of utility supply. This research investigation presents results from the analyses of the impact of statutory requirement, load demand and load type on the embedded generator (EG) grid–tied inverter anti-islanding protection settings and anti-islanding non-detection zone to minimize or reduce LV network operating safety risk upon the loss of utility supply.