Coordinating Secure and Distributed Operation of Electrical Networks Through Bilateral Agreements on Voltage and Power Envelopes

Network operation is becoming increasingly complex, mainly due to the growing penetration of renewable energy sources and less-predictable flexible loads. Part of this complexity stems from distributed operations and the difficulty of coordinating them. This paper introduces a new coordination mechanism for grid operation distributed across interconnected subnetworks following a hierarchy, such as network operators and end customers at different voltage levels. Voltage and power ranges, called operating envelopes, are agreed upon at the interfaces between subnetworks in hierarchical order. They ensure that, whatever situation arises within the envelopes, each operator can always restore static security on its own network at a bounded cost, while granting some operational flexibility to lower levels. During operation, as long as operators keep their interface voltages and powers within the agreed envelopes using local control means, static security can always be restored and no further coordination is required. In the second part, we propose a tractable method to compute such envelopes under simplifying assumptions and obtain a practical coordination mechanism. Experiments illustrate coordination between operators and customers across multiple voltage levels.