POWER BASED ALGORITHM TO PROVIDE LOSS OF GRID PROTECTION FOR EMBEDDEDGENERATION

The paper introduces a new protection algorithm designed to detect whe n the connection between an embedded generator operating and the utili ty grid is lost. Once loss of grid is detected, the intertie circuit b reaker connecting the embedded generator to the utility should be open ed to allow the orderly restoration of supply to other utility consume rs. Failure to detect the loss of grid and subsequently open the inter tie breaker could result in utility consumers receiving a low quality supply and could expose the embedded generator to severe damage should the utility grid be reconnected while out of synchronism with the emb edded generator. The paper describes the basis for the operation of th e protection algorithm and the role of the various elements together w ith the derivation of the tripping criterion. Its response to a series of power system switching scenarios are presented, including loss of grid, independent operation, out-of-phase reclosure, parallel operatio n together with a selection of fault studies, and for each it is shown to operate as required.