Enhancements of Protection Schemes for a Grid-Connected Industry Park with IPPs

Abstract

One major concern of the industry park (IP) with independent power producers (IPPs) is the protection scheme design, especially when the tie-line with the main grid is suddenly tripped due to some external faults. Under the worst scenarios, the IP may be completely shut down if no proper protection scheme is considered. In order to avoid such possible blackouts, it is necessary to design the relay setting along with appropriate load shedding (LS) schemes and generators' dynamic braking (DB) to maintain the balance between available generation and load, as well as to restore the system frequency and the voltage magnitude. In this paper, the expansion of production in one IP will be considered with deploying additional generators. Extensive numerical simulations under various contingencies are conducted to study dynamical interactions between relay settings and LS/DB mechanisms of this IP. possible Recommendations of revising current protective relay settings and appending an under-frequency relay at the point of common connections (PCC) are comprehensively investigated such that all loads and generation units in this IP still can sustain the unexpected power system disturbances caused by fault contingencies in the main utility system.