To support a high penetration of intermittent solar and wind power generation, many regions are planning to add new high capacity transmission lines. These additional transmission lines strengthen grid synchronization, but will also increase the grid's short circuit capacity, and furthermore will be very costly. With a highly interconnected grid and variable renewable generation, a small grid failure can easily start cascading outages, resulting in large scale blackout. We introduce the “digital grid,” where large synchronous grids are divided into smaller segmented grids which are connected asynchronously, via multileg IP addressed ac/dc/ac converters called digital grid routers. These routers communicate with each other and send power among the segmented grids through existing transmission lines, which have been repurposed as digital grid transmission lines. The digital grid can accept high penetrations of renewable power, prevent cascading outages, accommodate identifiable tagged electricity flows, record those transactions, and trade electricity as a commodity.

A fast transient stability program for an array processor (FPS AP-120B) connected to a host computer (DEC VAX-11/780) has been developed by using unique technique for improving the speed of transient stability studies. They are solving techniques of differential equations using a modified Euler method, effective use of vector operation, and programming techniques adapted to the array processor.