Control of a Battery Energy Storage System Accounting for the Charge Redistribution Effect to Dispatch the Operation of a Medium Voltage Feeder

We describe a process to dispatch the operation of a medium voltage distribution feeder and improve its quality-of-service using a battery energy storage system (BESS). It is organized according to a day-ahead and intra-day structure to allow the integration with electricity markets. In the former stage, the average power transit on a 5-minute resolution is determined for the next day of operation using adaptive black-box forecasting. In the latter stage, the feeder operation is dispatched according to the previously determined trajectory. The resulting tracking problem is accomplished by using the BESS to compensate for deviations from the dispatched plan, which are likely to occur due to forecasting errors. For the first time in the literature, the control strategy is realized using model predictive control (MPC) accounting for the battery charge redistribution effect. This phenomena is described using a state-of-the-art lithium battery model. A simulated proof-of-concept is given.

Battery Storage System Optimal Exploitation Through Physics-Based Model Predictive Control

Emil Namor, Mario Paolone, Fabrizio Sossan, Dimitri Torregrossa

Traditionally, the safe operation of a battery energy storage system (BESS) is achieved by imposing conservative constraints on its DC bus current and voltage. By using a computationally efficient single particle model (SPM), we propose to replace these constraints with the battery internal ion concentrations and electrical potentials in order to avoid these quantities to exceed hazardous limits. Indeed, the in-depth knowledge of the BESS internal states provided by the SPM, enhances the awareness of a control action and allows for a better exploitation of the BESS energy and power capabilities, while maintaining safe operational conditions. The target application is composed by a model predictive control (MPC) applied to a MW-class grid-connected BESS responsible to dispatch the operation of a medium voltage (20 kV) feeder interfacing heterogeneous loads and distributed generation. The performance of the proposed MPC are assessed and compared with respect to a traditional approach constraining the BESS DC bus current and voltage.

IEEE2017

Enhancing the dispatchability of distribution networks through utility-scale batteries and flexible demand

Luca Fabietti, Tomasz Tadeusz Gorecki, Colin Neil Jones, Emil Namor, Mario Paolone, Fabrizio Sossan

In this paper, the problem of dispatching the operation of a distribution feeder comprising a set of heterogeneous resources is investigated. The main objective is to track a power trajectory, called the dispatch plan, which is computed the day before the beginning of operation. In this paper, we propose a method to optimally compute the dispatch plan so as to optimize the operation of the feeder while making sure to allocate enough local reserves to absorb deviations of the realizations. Indeed, during real-time operation, due to the stochasticity of part of the resources in the feeder portfolio, tracking errors need to be absorbed in order to track the committed dispatch plan. This is achieved by modulating the power consumption of a utility-scale battery energy storage system and of the heating, ventilation and air conditioning system of a commercial controllable building. To this end, a hierarchical controller is designed to coordinate these two controllable entities while requiring a minimal communication infrastructure. Due to the inherent different response times of these systems, the power injection of the electrical battery is controlled at a sub-minute time-scale so as to absorb high-frequency tracking errors and, therefore, deliver the dispatch service. At a slower time-scale, the controllable building is controlled to maintain the state of charge for the electrical battery at a scheduled level by means of a model predictive controller. The model predictive controller is designed in order to account for both comfort and operational constraints of the controllable building, as well as power limits for the electrical storage. The effectiveness of the proposed control framework is demonstrated by means of both an extensive simulation analysis, as well as a set of 12 full day experimental results on the 20 kV distribution feeder in the campus of the Swiss institute of technology in Lausanne, that is comprised of: 1) A set of uncontrollable resources represented by five office buildings (350 kWp) and a roof-top photovoltaic installation (90 kWp), 2) a set of controllable resources, namely, a grid-connected electrical storage (720 kVA–500 kWh), and a fully-occupied multi-zone office building (45 kWp).

2018

Enhancing the dispatchability of distribution networks through utility-scale batteries and flexible demand

Luca Fabietti, Tomasz Tadeusz Gorecki, Colin Neil Jones, Emil Namor, Mario Paolone, Fabrizio Sossan

2018