A Bounded Model of the Communication Delay for System Integrity Protection Schemes

This paper investigates the latency of system integrity protection schemes (SIPSs) and proposes a bounded model of the communication delay. To be specific, SIPSs can be divided into wide-area protection and substation-area protection. For the former, the data buffering of phasor data concentrators and the automatic protection switching of synchronous optical network/synchronous digital hierarchy are utilized to limit the latency of regional and backbone networks, respectively; then, the communication delay is modeled as bounded, instead of average or stochastic in the literature. For the latter, the network calculus theory is used to restrict the latency in switched Ethernet networks, and the communication delay is modeled as bounded. In practice, SIPSs need to preprogram the time delay of protective relays and expect the communication delay as predictable or predetermined. Hence, the proposed bounded model is more realistic than the average or stochastic model. Further, the bounded model suggests the network dynamics and worst-case performances. It can be a useful tool in the relay setting as well as in the planning, design, and assessment of SIPS networks.