Grid-connected Battery Systems Research Articles

Model Predictive Control of Grid-Connected Battery Systems to avoid PV-induced Overvoltage

Photovoltaic (PV) power plants are currently built at a high rate, both small ones for single family houses and large-scale plants with a power output in the MW range. This development accelerated even more since the beginning of the energy crisis in 2021. Due to intermittent energy production, large voltage swings may result in the electrical grid, which are challenging for grid and operators. We are considering the problem of overvoltage in times of excessive PV production, which is well documented in the literature. To avoid overvoltage, without PV-curtailment or grid expansion, grid-connected battery systems are proposed. The research focus is on advanced control strategies for such systems which charge and discharge at appropriate times to reduce the overvoltage in the grid while simultaneously minimizing the required battery capacity. The work presented extends a previous contribution of the authors. The analysis was done in a simulation environment (MATLAB/Simulink).

Barriers to grid-connected battery systems: Evidence from the Spanish electricity market

Electrical energy storage is considered essential for the future energy systems. Among all the energy storage technologies, battery systems may provide flexibility to the power grid in a more distributed and decentralized way. In countries with deregulated electricity markets, grid-connected battery systems should be operated under the specific market design of the country. In this work, using the Spanish electricity market as an example, the barriers to grid-connected battery systems are investigated using utilization analysis. The concept of “potentially profitable utilization time” is proposed and introduced to identify and evaluate future potential grid applications for battery systems. The numerical and empirical analysis suggests that the high cycle cost for battery systems is still the main barrier for grid-connected battery systems. In Spain, for energy arbitrage within the day-ahead market, it is required that the battery wear cost decreases to 15 €/MWh to make the potentially profitable utilization rate higher than 20%. Nevertheless, the potentially profitable utilization of batteries is much higher in the applications when higher flexibility is demanded. The minimum required battery wear cost corresponding to 20% potentially profitable utilization time increases to 35 €/MWh for energy arbitrage within the day-ahead market and ancillary services, and 50 €/MWh for upward secondary reserve. The results of this study contribute to the awareness of battery storage technology and its flexibility in grid applications. The findings also have significant implications for policy makers and market operators interested in promoting grid-connected battery storage under a deregulated power market.

How deployment policies affect innovation in complementary technologies—evidence from the German energy transition

The transition in the electricity sector has entered a new phase, in which the complementary interplay of different technologies is key for the future functioning of the sector. A key question in this regard is how deployment policies for clean technologies such as wind and solar PV affect innovation in complementary technologies such as battery storage. We present a qualitative study from the German power sector, in which we investigate the impact of the feed-in tariff for renewable energy generation, on two complementary technologies: consumer and grid connected battery systems. We find direct and indirect effects of the feed-in tariff. Indirect effects are primarily about positive expectations regarding the future progression of the transition. As deployment policies drive this progression, providers of complementary technologies interpret these changes as promising signals for their business. Direct effects differ for consumer and grid connected batteries. We find that innovation in consumer battery systems is disincentivized by some deployment policy features, while there are no such effects for grid connected batteries. When re-designing deployment policies for the next stage of the energy transition, it is important to take their effects on complementary technologies into account, or to develop specific policies targeting complementary innovation.

Design and Control of a Multifunctional Grid-Connected Battery Energy Storage with Enhanced Performance Using SOGI

This paper presents the design and control of a multifunctional two-stage grid-connected battery to provide peak shaving along with reactive power and harmonics compensation. The system comprises of a bidirectional converter and a grid-connected voltage source converter (VSC). The bidirectional converter is controlled to provide the battery charging and to maintain constant DC-link voltage. A peak shaving logic is developed, and a ‘dual-mode synchronous reference frame control’ is designed using a moving average filter to control the VSC to provide peak shaving along with reactive power and harmonics compensation. A second-order generalized integrator is utilized to enhance system performance both during steady state and during mode transitions. The performance of the grid-connected battery system is tested for various scenarios in both simulation and experimentation. Simulated and test results validate the effectiveness of the proposed control in achieving the set objectives.

A Comparative Study of Vector Control and Model Predictive Control Technique for Grid Connected Battery System

Advancements made to battery energy storage technologies have led to increasing integration of battery systems with the grid. This paper presents a comparative study of the well-established vector control technique and the model predictive current control technique as applied to the grid connected battery systems. An electrical equivalent model of the battery is modeled and integrated with the grid using a three- phase bidirectional converter. The comparative study is shown for bidirectional flow of power to charge/discharge the battery from the grid. Also, the effects of model predictive control versus vector control technique are analyzed at an event of grid fault. Asymmetrical and symmetrical grid fault is considered for the comparison. All the modeling and simulation is performed in PSCADTM/EMTDCTM. The results are plotted using MATLAB R2017a. The results show that the model predictive control technique performs as good as the vector control technique for a battery connected grid system.

Optimal sizing and placement of distribution grid connected battery systems through an SOCP optimal power flow algorithm

The high variability and uncertainty introduced into modern electrical distribution systems due to decentralized renewable energy generators requires new solutions for grid management and power quality assurance. One of these possible solutions includes grid integrated energy storage. The appropriate size and placement of decentralized storage is highly dependent on purpose of the battery system and expected operational strategy. However, battery operational strategies are difficult to simulate simultaneously during a sizing and placement planning calculation. The motivation of this paper is to propose an algorithm that is capable of integrating sizing, placement and operational strategies of batteries into an Optimal Power Flow (OPF) distribution grid planning tool. The choice of the OPF approach permits to account for grid constraints which is more adapted for grid-connected storage devices compared to other approaches in the state of the art that are based only on an email balance analysis. This paper presents an alternating current (AC) multi-temporal OPF algorithm that uses a convex relaxation of the power flow equations to guarantee exact and optimal solutions with high algorithmic performance. The algorithm is unique and innovative due to the fact that it combines the simultaneous optimization of placement and sizing of storage devices taking into account load curves, photovoltaic (PV) production profiles, and distribution grid power quality constraints. The choice to invest in battery capacity is highly sensitive to the price of battery systems. The investment in battery systems solely for reducing losses an operational costs was proven not to be cost effective, however when battery systems are allowed to buy and sell electricity based on variable market prices they become cost effective. The assumptions used for this study shows that current battery system prices are too high to be cost effective even when allowing battery system market participation.