**Roshan Sharma***∗* **and Masoud Karimi-Ghartemani**

Department of Electrical and Computer Engineering, Mississippi State University, Starkville, MS 39762, USA; karimi@ece.msstate.edu

**\*** Correspondence: rs2142@msstate.edu

Received:10 January 2020; Accepted: 21 February 2020; Published: 25 February 2020

**Abstract:** At high penetration level of photovoltaic (PV) generators, their abrupt disturbances (caused by moving clouds) cause voltage and frequency perturbations and increase system losses. Meanwhile, the daily irradiation profile increases the slope in the net-load profile, for example, California duck curve, which imposes the challenge of quickly bringing on-line conventional generators in the early evening hours. Accordingly, this paper presents an approach to achieve two objectives: (1) address abrupt disturbances caused by PV generators, and (2) shape the net load profile. The approach is based on employing battery energy storage (BES) systems coupled with PV generators and equipped with proper controls. The proposed BES addresses these two issues by realizing flexible power ramp-up and ramp-down rates by the combined PV and BES. This paper presents the principles, modeling and control design aspects of the proposed system. A hybrid dc/ac study system is simulated and the effectiveness of the proposed BES in reducing the impacts of disturbances on both the dc and ac subsystems is verified. It is then shown that the proposed PV-BES modifies the daily load profile to mitigate the required challenge for quickly bringing on-line synchronous generators.

**Keywords:** PV generator; power ramping; battery energy storage; duck curve; hybrid dc/ac grids
