Voltage/load Control Strategy for Smart Distribution Grids with a High Penetration of Renewable Energy Sources

Abstract

The exponential increase of renewable energy sources (RESs) penetration in the power grid introduces the of voltage instability when RESs are integrated into medium and low voltage networks. This paper proposes a state-machine based voltage/load control strategy for different operating scenarios in a system comprised of a large RES power plant connected to a medium voltage bus at 11kV, and small RES systems scattered across low voltage networks at 415V. Three modes of operation are summarized, in which the appropriate action is taken according to the availability of RES power generation in the network and the loading condition of this network. Efficient power sharing is achieved via the utilization of a communication network deployed between the RES systems. The communication protocol of the network is represented in four messages adopted by the RES systems integrated into the grid. The effectiveness of the proposed voltage/load control strategy to surpass overvoltage cases caused by over-generation of RES power is illustrated through simulations. The proposed strategy can be adopted by either agreement between a utility and RES owners, or by making it the basis for a standard for RES installation.