SMART ENERGY MANAGEMENT OF MULTIPLE BATTERY TYPES FOR AGGREGATORS USE CONSIDERING NEGOTIATED CONTRACTS WITH THE DISTRIBUTION SYSTEM OPERATOR AND BATTERY DEGRADATION

Abstract

This paper presents a methodology for optimal energy management of battery energy storage systems for aggregators use in distribution systems considering photovoltaic generation, demand contracts, and lifetime degradation. The methodology sets the optimum operation of the battery, define a trade-off between profit/lifetime of the battery dispatch and reduce the aggregator tariff bill. The dispatch optimization is carried out on a 48h forecasting model, where the best strategy is the one that guarantees a good operation for the day n+1 and day n+2. A nonlinear optimization approach sets battery dispatch, under operational constraints given by the Distribution System Operator contract and the battery state of charge constraint. Three types of battery chemistry are used, the lead acid, lithium ion and vanadium redox. Also, for each battery type the best methodology strategy is defined. Regarding the methodology, a neural network is used for forecasting of demand values, PV generation and tariff prices. Battery degradation cost is controlled in daily operation based on cycles and cost. Moreover, for total lifetime estimation, the Rainflow Counting technique is used through the depth of discharge. The results define an operation for the battery that allows economic profit, without compromising the lifetime.