The Design and Analysis of Large Solar PV Farm Configurations With DC-Connected Battery Systems

Abstract

Typically, solar inverters curtail or "clip" the available power from the PV system when it exceeds the maximum ac capacity. This paper discusses a battery system connected to the dc-link of an inverter to recuperate this PV energy. Contrary to conventional approaches, which employ two dc-dc converters, one each for the battery and solar PV system, the proposed configuration utilizes a single dc-dc converter capable of simultaneously operating as a charge controller and a maximum power point tracking (MPPT) tracking device. In addition to improving the overall system capacity factor, increasing the conversion efficiencies and ensuring MPPT stability, the proposed configuration offers a simple solution for adding energy storage to existing PV installations. With this configuration, the excess power that will otherwise be curtailed due to inverter rating limitations is stored in the battery and supplied to the grid during periods of reduced irradiance. Moreover, a systematic methodology for sizing a dc-bus connected battery to minimize total PV energy curtailed was developed using an annual PV generation profile at the Louisville Gas and Electric and Kentucky Utilities (LG&E and KU) E.W. Brown solar facility at Kentucky. The detailed behavior of the proposed system and its power electronics controls and operations were validated with case studies developed in PSCAD T M /EMTDC T M for variable power generation and PV output power smoothing.

A two-stage coordination strategy for the control of distributed storage at the household level—Arbitrage between users preferences and distribution grid objectives

“…Finally, potential curtailment of generation is represented by constraints (7) and (8). In practice, curtailment is possible with a degradation of the MPPT (maximum power point tracking) of the solar generator, which translates in a modified voltage reference at the level of the photovoltaic modules [13]. Also, Note that taking into account this storage efficiency consists of accounting for both charging and discharging losses while disaggregating two operating modes thanks to a binary variable u n,t s+ (for charging in (3)) which requires the implementation of mixed integer programming problems.…”

PV Farm Ancillary Function for Voltage Sag Mitigation Caused by Inrush Current of an Induction Motor

“…Integrations of energy storage, inverter, and control become important to overcome power quality problems. The research that has been done for this integration shows significant achievements [26][27][28][29][30][31].…”

Efficiency Comparison of DC and AC Coupling Solutions for Large-Scale PV+BESS Power Plants

“…In reference [28], a DC-coupling solution that utilizes a single battery dc-dc converter capable of simultaneously operating as a charge controller and a maximum power point tracking (MPPT) device was analyzed. The battery coupling solution in [28] is similar to the DC-coupling analyzed in this paper.…”

“…In reference [28], a DC-coupling solution that utilizes a single battery dc-dc converter capable of simultaneously operating as a charge controller and a maximum power point tracking (MPPT) device was analyzed. The battery coupling solution in [28] is similar to the DC-coupling analyzed in this paper. A multi-MW power plant of 14 MWp of PV and a 1 MW/2 MWh of BESS is considered a case study, but consideration about the PCS efficiency and comparisons with the AC-coupling counterpart was not provided.…”