Search

This study introduces a coordinated control approach to address the challenge of volt-var optimization (VVO), incorporating load tap-changing transformers, step-voltage regulators, and switched-capacitor banks, along with a photovoltaic (PV)-integrated microgrid. The harmony search (HS) metaheuristic algorithm was applied to efficiently compute the globally optimal operating parameters for these devices, ensuring robust performance across fluctuating operating conditions. The key aims of the volt-var control strategy were to achieve substantial reductions in active power losses, peak demand, and voltage deviations throughout the distribution system, while simultaneously maintaining bus voltages within acceptable regulatory limits under all possible load scenarios. The optimization problem is a mixed-integer nonlinear program with discrete decision variables, binary variables representing capacitor bank switching states (on/off), integer variables for voltage regulator tap positions, continuous variables for the microgrid’s injected current, and nonlinear network power-flow constraints. The proposed methodology was tested and validated on the standard IEEE 13-node distribution test feeder. Time-series simulations used realistic daily load profiles from the main grid, along with the microgrid’s PV output, both resolved at 15-minute intervals. All power flow computations were carried out with OpenDSS (version 9.5.1.1, released in 2022), an established open-source distribution system analysis tool. The developed control framework supports both real-time operation and long-term planning studies. Simulation results showed that the integrated volt-var coordination significantly reduced total active power losses, lowered peak demand, and effectively mitigated voltage variations across the network.

The usefulness of Hybrid Energy Storage Systems (HESSs) has been demonstrated across various application areas, including Charging Stations (CSs), grid services, and microgrids. HESSs combine two or more individual Energy Storage Systems (ESSs) to merge the advantages of each technology and enhance overall system performance. In this study, we introduce a novel power management controller, termed the Hybrid Controller, designed for efficient charging and discharging of the HESS while accounting for its State of Charge (SoC) and the fluctuating supply and load conditions. The Hybrid Controller improves HESS utilization by minimizing energy exchange with the grid, thereby prioritizing and maximizing the use of available Photovoltaic (PV) power. The effectiveness of the proposed approach was evaluated through simulations using several performance indicators, namely Autarky, charge/discharge cycles, and Self-Consumption (SC). For this purpose, we defined 24 scenarios across different locations in Germany.