Impact of embedded generation on emergency reserve

The growth of embedded generation (EG) capacity in many power supply systems has brought a number of advantages. A potential disadvantage for isolated systems is that generation loss incidents can trigger nuisance tripping of the EG. This undermines the emergency reserve provided to mitigate such a loss. The paper presents an EG loss of mains protection technique, which avoids nuisance tripping during an under-frequency transient. It is also shown that EG can supplement emergency reserve from utility generation. Experimental results and simulations demonstrate how this may be achieved by exploiting the short-term overload capability of diesel generator sets