Distributed compensation of a large intermittent energy resource in a distribution feeder
In a smart grid demonstration project in New Mexico, a combination of a 500kW PV farm and a 1MWh utility scale storage system which consists of a 500kW ultra fast smoothing battery and a 250kW shifting battery are installed. At a nearby location, a micro grid demonstration which incorporates a 240kW natural gas-powered generator, a 80kW fuel cell, a 50kW PV generator, a lead-acid battery storage system, and hot and cold thermal storage is installed. With the current configuration, the storage system associated with the 500kW PV is able to smooth PV output, to shift the peak generation to the time of peak consumption and also to firm the PV resource as a fixed amount of power. The problem is how the system would be managed in presence of several distributed resources with different ramp rates and capacities and different operation costs, which would reduce the stress placed on the battery. In this paper, the results of the different studies on the system model are discussed. A complete feeder model in GridLAB-D is used to demonstrate several control algorithms. In one scenario, all other available generations are planned to compensate the PV generation ramp rate based on their individual capacity. Each agent will compensate the ramp rate of the total generation of the higher priority agents based on its own capacity. In another scenario, individual agents try to compensate the deficit in power generation scheduled for the whole system. Every particular agent is responsible for compensating the difference between the scheduled and the total generation of the higher priority agents.