Optimal Provision of Concurrent Primary Frequency and Local Voltage Control from a BESS Considering Variable Capability Curves: Modelling and Experimental Assessment

TL;DR

This paper introduces a real-time control method for BESS that optimally manages primary frequency and voltage regulation by considering variable converter capabilities and battery state, validated through experiments.

Contribution

It presents a novel control framework that jointly considers variable power capabilities and battery state-of-charge for concurrent grid services, with an efficient algorithm and experimental validation.

Findings

Effective control of BESS for frequency and voltage regulation

Validation on a 720 kVA/560 kWh BESS demonstrates performance

Joint consideration of converter capabilities and SOC improves service provision

Abstract

This paper proposes a control method for battery energy storage systems (BESSs) to provide concurrent primary frequency and local voltage regulation services. The actual variable active and reactive power capability of the converter, along with the state-of-charge of the BESS, are jointly considered by the optimal operating point calculation process within the real-time operation. The controller optimizes the provision of grid services, considering the measured grid and battery statuses and predicting the battery DC voltage as a function of the current trajectory using a three-time-constant model (TTC). A computationally-efficient algorithm is proposed to solve the formulated optimal control problem. Experimental tests validate the proposed concepts and show the effectiveness of the employed control framework on a commercial utility-scale 720 kVA/560 kWh BESS.