Distributed Optimal Control of Voltages in Weak Sub-transmission Networks with High Penetration of Solar Power

With grid connected solar power plants, the voltages in a weak sub-transmission system are likely to vary significantly and quickly. This paper addresses the problem of voltage variation in the network with load aggregators (LAs) through an optimal dispatch scheme, where the control objective is to maintain voltages of critical buses within predefined ranges with a least total economic cost. In our scheme, rather than sharing global information, the optimal dispatch strategy is achieved in a distributed manner by only exchanging limited information between neighboring LAs, and includes coordination with conventional control to minimize customer disruption. The effectiveness of the proposed control scheme is tested in a modified IEEE 30-bus system.