Self-healing circuits at Southern California Edison

Southern California Edison has been investigating and demonstrating self-healing distribution circuit technologies for many years. Initial work resulted in the installation of automated mid-point switches that sense loss of voltage on most urban distribution circuits. The next generation of this system was demonstrated on the Circuit of the Future. This system uses fault interrupting switches throughout the circuit that communicate with each other using fiber-optic cables. This arrangement allows the protection system to identify the faulted circuit section and isolate it before the substation breaker trips. The latest demonstration of self-healing circuits is being designed for implementation on the Irvine Smart Grid Demonstration project. This self-healing circuit variation places fault interrupting switches on the distribution circuit with communications being accomplished with low-latency radios. Again, the faulted section of the circuit is isolated before the substation breaker is tripped. Two radial circuits are also looped so that when the faulted section of the circuit is tripped, all other sections of the circuit stay energized.